EP3663429B1 - Hot dip galvanizing apparatus - Google Patents

Description

The present invention relates to the technical field of galvanizing iron-based or iron-containing components, in particular steel-based or steel-containing components (steel components), preferably for the automotive or motor vehicle industry, but also for other technical fields of application (e.g. for the construction industry, the field of general mechanical engineering, the electrical industry, etc.), by means of hot-dip galvanizing (hot-dip galvanizing).

In particular, the present invention relates to the inventive use of a plant for hot-dip galvanizing (hot-dip galvanizing) according to claims 1-14.

Metallic components of any kind made of ferrous material, especially components made of steel, often require efficient protection against corrosion due to their application. In particular, components made of steel for motor vehicles (motor vehicles), such as cars, trucks, commercial vehicles, etc., but also for other technical areas (e.g. construction industry, mechanical engineering, electrical industry, etc.), require efficient corrosion protection that can withstand long-term stress.

In this context, it is known to protect steel-based components against corrosion by means of galvanizing (galvanizing). During galvanizing, the steel is provided with a generally thin zinc layer to protect the steel from corrosion. Various galvanizing processes can be used to galvanize steel components, i.e. to cover them with a metallic zinc coating, in particular hot-dip galvanizing (also known synonymously as hot-dip galvanizing), spray galvanizing (flame spraying with zinc wire), diffusion galvanizing (Sherard galvanizing), electrolytic galvanizing, non-electrolytic galvanizing using zinc flake coatings and mechanical galvanizing. There are major differences between the aforementioned galvanizing processes, in particular with regard to the process implementation, but also with regard to the nature and properties of the zinc layers or zinc coatings produced.

The most important method for protecting steel from corrosion using metallic zinc coatings is hot-dip galvanizing (hot-dip galvanizing). Steel is dipped continuously (e.g. strip and wire) or piece by piece (e.g. components) into a heated tank filled with liquid zinc at temperatures of around 450 °C to 600 °C (melting point of zinc: 419.5 °C), so that a resistant alloy layer of iron and zinc forms on the steel surface, and a very firmly adhering pure zinc layer forms on top of that.

Hot-dip galvanizing has been a recognized and proven method for many years to protect parts and components made of iron materials, especially steel materials, from corrosion. As previously described, the typically pre-cleaned or pre-treated component is immersed in a liquid-hot zinc bath, where it reacts with the molten zinc and, as a result, forms a relatively thin zinc layer that is metallurgically bonded to the base material.

In hot-dip galvanizing, a distinction is made between discontinuous batch galvanizing (cf. e.g. DIN EN ISO 1461) and continuous strip and wire galvanizing (cf. e.g. DIN EN 10143 and DIN EN 10346). Both batch galvanizing and strip and wire galvanizing are standardized processes. Continuously galvanized steel strip and continuously galvanized wire are each a preliminary or intermediate product (semi-finished product) which is further processed after galvanizing, in particular by forming, punching, cutting, etc., whereas components to be protected by batch galvanizing are first completely manufactured and only then hot-dip galvanized (which protects the components all around from corrosion). Batch galvanizing and strip/wire galvanizing also differ in terms of the thickness of the zinc layer, which results in different protection periods - also depending on the zinc layer. The zinc layer thickness of strip-galvanized sheets is usually a maximum of 20 to 25 micrometers, whereas the zinc layer thickness of batch-galvanized steel parts is usually in the range of 50 to 200 micrometers and even more.

Hot-dip galvanizing provides both active and passive corrosion protection. Passive protection is provided by the barrier effect of the zinc coating. Active corrosion protection is provided by the cathodic effect of the zinc coating. Compared to more noble metals in the electrochemical series, such as iron, zinc serves as a sacrificial anode, which protects the iron underneath from corrosion until it is completely corroded itself.

In the so-called batch galvanizing according to DIN EN ISO 1461, the hot-dip galvanizing of mostly larger steel components and structures takes place. Steel-based blanks or finished workpieces (components) are dipped into the molten zinc bath after pre-treatment. By dipping, inner surfaces, weld seams and hard-to-reach areas of the workpieces or components to be galvanized can be easily reached.

Conventional hot-dip galvanizing, in particular dip galvanizing, is based in particular on dipping iron or steel components into a zinc melt to form a zinc coating or a zinc coating on the surface of the components. To ensure the adhesion, integrity and uniformity of the zinc coating, careful surface preparation of the components to be galvanized is generally required beforehand, which usually includes degreasing followed by rinsing, subsequent acid pickling followed by rinsing and finally flux treatment (i.e. so-called fluxing) followed by drying.

For reasons of process economy and cost-effectiveness, when galvanizing identical or similar components (e.g. series production of automotive components), these are typically brought together or grouped for the entire process (in particular by means of a common product carrier, for example designed as a crossbeam or frame, or a common holding or fastening device for a large number of these identical or similar components). For this purpose, a plurality of components are attached to the product carrier using holding devices, such as slings, tie wires or the like. The components are then fed in a grouped state via the product carrier to the individual treatment steps or stages of hot-dip galvanizing.

The typical process sequence for conventional hot-dip galvanizing is usually as follows:

First, the surfaces of the components in question are degreased to remove residues of grease and oil, whereby aqueous alkaline or acidic degreasing agents can usually be used as degreasing agents. After cleaning in the degreasing bath, a rinsing process usually follows, typically by immersion in a water bath, in order to prevent degreasing agents from being carried over with the galvanized material into the subsequent process step of pickling, whereby this is particularly important when changing from alkaline degreasing to acidic pickling.

This is followed by a pickling treatment (pickling), which is used in particular to remove inherent contaminants such as rust and scale from the steel surface. Pickling is usually carried out in diluted hydrochloric acid, whereby the duration of the pickling process depends, among other things, on the state of contamination (e.g. degree of rust) of the galvanized material and the acid concentration and temperature of the pickling bath. To avoid or minimize the carryover of acid and/or salt residues with the galvanized material, a rinsing process (rinsing step) usually takes place after the pickling treatment.

This is followed by what is known as fluxing (also known as flux treatment), in which the previously degreased and pickled steel surface is treated with a flux, which typically comprises an aqueous solution of inorganic chlorides, most frequently a mixture of zinc chloride (ZnCl ₂ ) and ammonium chloride (NH ₄ Cl). On the one hand, the purpose of the flux is to carry out a final, intensive, fine cleaning of the steel surface before the steel surface reacts with the molten zinc, to dissolve the oxide skin of the zinc surface and to prevent further oxidation of the steel surface until the galvanizing process. On the other hand, the flux is intended to increase the wettability between the steel surface and the molten zinc. After the flux treatment, drying usually follows in order to create a solid flux film on the steel surface and to remove adhering water, so that subsequent undesirable reactions (in particular the formation of water vapor) in the liquid zinc dip bath are avoided.

The components pretreated in the above-mentioned manner are then hot-dip galvanized by immersing them in the liquid zinc melt. When hot-dip galvanizing with pure zinc, the zinc content of the melt is at least 98.0 wt.% in accordance with DIN EN ISO 1461. After the item to be galvanized has been immersed in the molten zinc, it remains in the zinc melt bath for a sufficient period of time, in particular until the item to be galvanized has assumed its temperature and is coated with a zinc layer. Typically, the surface of the zinc melt is cleaned of oxides, zinc ash, flux residues and the like, in particular, before the item to be galvanized is then pulled out of the zinc melt again. The component hot-dip galvanized in this way is then subjected to a cooling process (e.g. in air or in a water bath). Finally, any holding devices for the component, such as slings, tie wires or the like, are removed.

Following the galvanizing process, a post-processing or post-treatment process can usually be carried out, which can be complex. This involves removing as much of the excess zinc bath residue as possible, particularly drips from the zinc solidifying on the edges, as well as oxide or ash residues that adhere to the component.

One criterion for the quality of hot-dip galvanizing is the thickness of the zinc coating in µm (micrometers). The DIN EN ISO 1461 standard specifies the minimum values of the required coating thicknesses that must be delivered during batch galvanizing depending on the material thickness. In practice, the coating thicknesses are significantly higher than the minimum coating thicknesses specified in DIN EN ISO 1461. In general, zinc coatings produced by batch galvanizing have a thickness in the range of 50 to 200 micrometers and even more.

During the galvanizing process, a coating of iron/zinc alloy layers of various compositions forms on the steel part as a result of the mutual diffusion of the liquid zinc with the steel surface. When the hot-dip galvanized objects are removed, a layer of zinc - also known as the pure zinc layer - remains on the top alloy layer, which corresponds in composition to the zinc melt. Due to the high temperatures during hot-dip dipping, a relatively brittle layer based on an alloy (mixed crystals) between iron and zinc initially forms on the steel surface, and only then does the pure zinc form on top of this. Zinc layer. The relatively brittle iron/zinc alloy layer improves the bond strength with the base material, but makes it more difficult to form the galvanized steel. Higher silicon contents in the steel, such as those used in particular to so-called calm the steel during its production, lead to increased reactivity between the zinc melt and the base material and, as a result, to strong growth of the iron/zinc alloy layer. This leads to the formation of relatively large total layer thicknesses. Although this enables a very long corrosion protection period, the risk of the layer flaking off under mechanical stress, particularly local impacts, and the corrosion protection effect being impaired as a result, also increases with increasing zinc layer thickness.

In order to counteract the problem described above of the occurrence of the rapidly growing, brittle and thick iron/zinc alloy layer and to enable thinner layer thicknesses with simultaneously high corrosion protection during galvanizing, it is known from the state of the art to add additional aluminum to the zinc melt or the liquid zinc bath. For example, by adding 5% by weight of aluminum to a liquid zinc melt, a zinc/aluminum alloy with a lower melting temperature than pure zinc is produced. By using a zinc/aluminum melt (Zn/Al melt) or a liquid zinc/aluminum bath (Zn/Al bath), on the one hand, significantly thinner layer thicknesses can be achieved for reliable corrosion protection (generally below 50 micrometers); On the other hand, the formation of the brittle iron/tin alloy layer is avoided because the aluminium - without committing to a specific theory - first forms a barrier layer on the steel surface of the component in question, onto which the actual zinc layer is then deposited.

Components hot-dip galvanized with a zinc/aluminium melt can therefore be easily formed, but still have improved corrosion protection properties - despite the significantly lower layer thickness compared to conventional hot-dip galvanizing with a virtually aluminum-free zinc melt.

A zinc/aluminium alloy used in the hot-dip galvanizing bath has improved fluidity properties compared to pure zinc. In addition, zinc coatings produced by hot-dip galvanizing using such zinc/aluminium alloys have greater corrosion resistance (which is two to six times better than that of pure zinc), better appearance, improved formability and better paintability than zinc coatings formed from pure zinc. In addition, lead-free zinc coatings can also be produced using this technology.

Such a hot-dip galvanizing process using a zinc/aluminium melt or using a zinc/aluminium hot-dip galvanizing bath is known, for example, from WO 2002/042512 A1 and the relevant publication equivalents to this patent family (e.g. EP 1 352 100 B1 , DE 601 24 767 T2 and US 2003/0219543 A1 ). Suitable fluxes for hot-dip galvanizing using zinc/aluminium molten baths are also disclosed there, since flux compositions for zinc/aluminium hot-dip galvanizing baths must be different from those for conventional hot-dip galvanizing with pure zinc. The process disclosed there can be used to produce corrosion protection coatings with very low layer thicknesses (generally well below 50 micrometers and typically in the range of 2 to 20 micrometers) and with very low weight and high cost efficiency, which is why the process described there is used commercially under the name microZINQ ^® process.

However, state-of-the-art hot-dip galvanizing processes which use a zinc/aluminium melt or a zinc/aluminium hot-dip galvanizing bath (such as WO 2002/042512 A1 ) Fluxes containing significant amounts of lead chloride to enable good wettability with respect to the flux treatment, as well as nickel chloride to ensure good temperature resistance of the flux, and possibly also other transition or heavy metal chlorides to achieve other desired properties. In addition, the pH value of the flux bath is generally adjusted in state-of-the-art hot-dip galvanizing processes using hydrochloric acid (hydrochloric acid), which may promote undesirable hydrogen embrittlement of the metal substrate to be treated.

With regard to the formation of the zinc layer and its properties, it has been shown that these can be significantly influenced by alloying elements in the zinc melt. One of the most important elements here is aluminum: It has been shown that with an aluminum content of just 100 ppm (weight-based) in the zinc melt, the appearance of the resulting zinc layer can be improved to a brighter, shinier appearance. As the aluminum content in the zinc melt increases up to 1,000 ppm (weight-based), this effect increases steadily. Furthermore, it has been shown - as already described - that from an aluminum content in the zinc melt of 0.12 wt.%, an intermetallic Fe/Al phase forms between the iron material and the zinc layer, which leads to the otherwise usual diffusion processes between iron and zinc melt being inhibited and thus the growth of the Zn/Fe phases being significantly reduced; as a result, significantly thinner zinc layers result from this aluminum content in the zinc melt. Finally, it has been shown that the anti-corrosive effect of the resulting zinc layer increases with increasing aluminum content in the zinc melt; the basis for this is that the Al/Zn compounds form significantly more stable covering layers more quickly.

Well-known examples of the commercial use of aluminum-containing zinc melts are the so-called Galfan ^® process and the aforementioned microZINQ ^® process with an aluminum content in the zinc melt typically in the range of 4.2 wt.% to 6.2 wt.%. The advantage of this alloy is, among other things, that around the average value of 5 wt.% there is a eutectic composition of the Al/Zn system with a melting point of 382 °C, which enables a reduction in the operating temperature in the galvanizing process.

However, the disadvantage of using aluminum-alloyed or aluminum-containing zinc melts (Zn/Al melts) is that it is much more difficult to wet the iron or steel surface to be galvanized with the liquid-hot Zn/Al melt and the reaction between the Zn/Al melt and the iron or steel surface of the component to be treated is much more sensitive and difficult to handle due to the high affinity of aluminum to iron. This leads to the need for significantly higher requirements for the cleanliness of the steel surface after the cleaning steps and before immersion in the Zn/Al melt compared to a process using pure zinc melt. In addition, the use of A suitable flux and preheating of the material to be galvanized are required so that the reaction between the melt and the base material and, with it, the formation of a homogeneous, closed zinc coating can take place.

In general, when using aluminum-alloyed or aluminum-containing zinc melts (Zn/Al melts), special fluxes are required for the flux treatment (flux treatment), which often contain heavy metal compounds (usually heavy metal chlorides) that are not always ecologically compatible or undesirable, in particular lead and/or nickel chloride, but possibly also cobalt, manganese, tin, antimony and/or bismuth chloride, which are required to ensure subsequent perfect hot-dip galvanizing, in particular without defects on the galvanized components. In these fluxes, which are specially designed for hot-dip galvanizing with aluminum-alloyed or aluminum-containing zinc melts (Zn/Al melts), the lead chloride is intended in particular to reduce the surface tension and in this way to improve the wettability of the component surface to be treated with the liquid Zn/Al melt, while the nickel chloride is intended to improve the temperature resistance of the flux, in particular with regard to the drying that usually follows the flux treatment.

Nevertheless, when using aluminum-alloyed or aluminum-containing zinc melts (Zn/Al melts) according to the state of the art, especially when using fluxes known from the state of the art, there remains a high sensitivity to foreign contaminants, such as fats and oils, which are either not dissolved in the upstream cleaning stages or are caused by carryover through the cleaning stages despite rinsing processes. This is because in the pretreatment steps preceding the actual galvanizing process, the complete removal of all foreign and native contaminants (such as fats and oils, germs, oxidation residues, etc.) from the steel surface is necessary, whereby several alkaline degreasing baths and acidic pickling baths are usually run through for this purpose, whereby the alkaline or acidic media are rinsed off in the usually multiple rinsing stages downstream of the respective degreasing and cleaning baths in order to avoid carryover into the subsequent process step. In practice, however, it turns out that under the conditions of the galvanizing process, especially with large Volumes of the pretreatment baths, high throughputs of the most diverse components to be galvanized, some of which have a very high variance in the surface conditions in the delivery state, etc., particularly when using aluminum-alloyed or aluminum-containing zinc melts (Zn/Al melts) according to the state of the art, defects on the material to be galvanized repeatedly occur, which are typically due to inadequate cleaning, possibly in conjunction with insufficiently effective flux treatment.

The internet excerpt according to Roeling: " Steel construction work aid", 28 April 2010 (2010-04-28), XP055677329, (http://bauforumstahl.de/upload/documents/publikationen/ arbeitshilfen/sta.01.4.pdf ) concerns general statements and principles of hot-dip galvanizing in a liquid zinc melt.

In addition, the EP 2 725 115 A1 a flux composition for treating a metallic surface, the flux composition comprising more than 40 and less than 70 wt.% zinc chloride, 10 to 30 wt.% ammonium chloride, more than 6 and less than 30 wt.% of a combination of at least two alkali metal chlorides including sodium chloride and potassium chloride, 0 to 2 wt.% lead chloride, and 0 to 15 wt.% tin chloride.

Furthermore, the WO 95/04607 A1 a hot-dip galvanizing process for treating steel components, whereby an aqueous flux is applied to the steel components, the components are then preheated and exposed to a non-reducing atmosphere to dry the flux. Additional energy in the form of heat is supplied to the pretreated component, which exceeds the energy required to dry the flux, and the component is then fed into a molten zinc bath for hot-dip galvanizing.

The DE 23 17 600 A1 relates to an aqueous flux solution for hot-dip galvanizing, which contains zinc chloride and optionally alkali chlorides. In addition, the flux solution contains aluminum chloride and/or hydrogen chloride and optionally a maximum of 4% by weight of ammonium chloride, based on the zinc chloride contained in the solution and the optionally contained alkali chlorides, and also known corrosion inhibitors.

Furthermore, the EP 1 694 880 A2 an aqueous flux solution for hot-dip galvanizing steel components, wherein the flux solution contains 200 to 600 g/l zinc chloride and ammonium chloride, wherein the molar ratio between ammonium chloride and zinc chloride is 1.7 to 3.3 and wherein the flux solution contains 8 g/l to 80 g/l aluminum chloride (AlCl ₃ ).

The problem underlying the present invention therefore consists in providing a method for hot-dip galvanizing (hot-dip galvanizing), in particular of iron-based or iron-containing components, preferably steel-based or steel-containing components (steel components), using an aluminum-containing or aluminum-alloyed zinc melt and a corresponding system for carrying out this method and, in addition, a flux or flux bath that can be used in the process, wherein the previously described disadvantages of the prior art are to be avoided at least as far as possible or at least mitigated.

In particular, such a process is to be provided which, compared to conventional hot-dip galvanizing processes using an aluminum-containing or aluminum-alloyed zinc melt, enables improved process economy and/or a more efficient, in particular more flexible and/or more reliable, in particular less error-prone process sequence and/or improved ecological compatibility.

In particular, such a process should not require the use of significant amounts of heavy metal compounds, in particular heavy metal chlorides, such as lead and/or nickel chloride, but possibly also other heavy metal chlorides, such as cobalt, manganese, tin, antimony and/or bismuth chloride, as part of the flux treatment and thus have improved ecological compatibility, but nevertheless reliably ensure that the treated components are galvanized efficiently and without defects.

To solve the problem described above, the present invention proposes the inventive use of a plant for hot-dip galvanizing iron or steel components according to claim 1; further, in particular special and/or advantageous embodiments of the inventive use are the subject of the relevant use subclaims (claims 2 to 14).

It goes without saying that embodiments, embodiments, advantages and the like which are described below only for one aspect in order to avoid repetition naturally also apply to the other aspects without this requiring separate mention.

With regard to all relative or percentage weight-related information mentioned below, in particular relative quantity or weight information, it should also be noted that these are to be selected by the person skilled in the art within the scope of the present invention in such a way that, when taken together, including all components or ingredients, in particular as defined below, they always add up to 100% or 100% by weight; however, this is self-evident to the person skilled in the art.

Furthermore, the person skilled in the art may, if necessary - depending on the application or the individual case - deviate from the range specifications given below without departing from the scope of the present invention.

In addition, all values or parameter specifications or the like mentioned below can in principle be determined using standardized or explicitly specified determination procedures or, if not, using determination or measurement methods that are familiar to a person skilled in the art.

Having said that, the present invention will now be explained in detail below.

1. (A) mindestens eine Entfettungsvorrichtung zur Entfettungsbehandlung von Eisen- oder Stahlbauteilen; in Prozessrichtung nachgeschaltet oder stromabwärts zu (A)
2. (B) gegebenenfalls mindestens eine Spülvorrichtung zum Spülen von in der Entfettungsvorrichtung (A) entfetteten Eisen- oder Stahlbauteilen; in Prozessrichtung nachgeschaltet oder stromabwärts zu (B)
3. (C) mindestens eine Beizvorrichtung zur Beizbehandlung von in der Entfettungsvorrichtung (A) entfetteten und gegebenenfalls in der Spülvorrichtung (B) gespülten Eisen- oder Stahlbauteilen; in Prozessrichtung nachgeschaltet oder stromabwärts zu (C)
4. (D) gegebenenfalls mindestens eine Spülvorrichtung zum Spülen von in der Beizvorrichtung (C) gebeizten Eisen- oder Stahlbauteilen; in Prozessrichtung nachgeschaltet oder stromabwärts zu (D)
5. (E) mindestens eine Flussmittelbehandlungsvorrichtung zur Flussmittelbehandlung von in der Beizvorrichtung (C) gebeizten und gegebenenfalls in der Spülvorrichtung (D) gespülten Eisen- oder Stahlbauteilen, wobei die Flussmittelbehandlungsvorrichtung mindestens ein Flussmittelbad mit einer Flussmittelzusammensetzung enthält,
   • wobei das Flussmittelbad eine ein Alkohol/Wasser-Gemisch enthaltende flüssige Phase umfasst, wobei die flüssige Phase des Flussmittelbades die Flussmittelzusammensetzung enthält, wobei der Alkohol des Alkohol/Wasser-Gemischs des Flussmittelbades ein mit Wasser mischbarer und/oder ein in Wasser löslicher Alkohol ist und ausgewählt ist aus der Gruppe von linearen oder verzweigten, gesättigten oder ungesättigten, aliphatischen, cycloaliphatischen oder aromatischen, primären, sekundären oder tertiären einwertigen C₁-C₄-Alkoholen und deren Mischungen, und
   • wobei die Flussmittelzusammensetzung als Inhaltsstoffe
     1. (i) Zinkchlorid (ZnCl₂) in Mengen im Bereich von 50 bis 95 Gew.-%,
     2. (ii) Ammoniumchlorid (NH₄Cl) in Mengen im Bereich von 5 bis 45 Gew.-%,
     3. (iii) mindestens ein Alkali- und/oder Erdalkalisalz in Mengen im Bereich von 0,1 bis 25 Gew.-% und
     4. (iv) mindestens ein Aluminiumsalz und/oder mindestens ein Silbersalz in Mengen im Bereich von 5 • 10^-5 bis 2 Gew.-%
   • enthält, wobei alle vorgenannten Mengenangaben auf die Zusammensetzung bezogen sind und derart auszuwählen sind, dass insgesamt 100 Gew.-% resultieren,
     und
   • wobei die Flussmittelzusammensetzung vollkommen frei von Bleichlorid (PbCl₂) und Nickelchlorid (NiCl₂) ausgebildet ist;
   • in Prozessrichtung nachgeschaltet oder stromabwärts zu (E)
6. (F) mindestens eine Trocknungsvorrichtung (F) zur Trocknung von in der Flussmittelbehandlungsvorrichtung (E) einer Flussmittelbehandlung unterzogenen Eisen- oder Stahlbauteilen,
   • wobei die Trocknungsvorrichtung (F) mittels einer Steuerungseinrichtung derart gesteuert wird, dass die Trocknungsbehandlung derart durchgeführt wird, dass die Oberfläche des Eisen- oder Stahlbauteils bei der Trocknung eine Temperatur im Bereich von 100 bis 300 °C aufweist,
   • wobei die Trocknungsvorrichtung (F) mindestens einen Einlass zum Einführen und/oder Einlassen von Luft aufweist und
   • wobei die Trocknungsvorrichtung (F) mindestens eine Trocknungseinrichtung umfasst;
   • in Prozessrichtung nachgeschaltet oder stromabwärts zu (F)
7. (G) mindestens eine Feuerverzinkungsvorrichtung zur Feuerverzinkung von in der Flussmittelbehandlungsvorrichtung (E) einer Flussmittelbehandlung unterzogenen und gegebenenfalls in der Trocknungsvorrichtung (F) getrockneten Eisen- oder Stahlbauteilen,
   wobei die Feuerverzinkungsvorrichtung mindestens ein eine aluminiumhaltige Zinkschmelze enthaltendes Verzinkungsbad, ausgebildet zum Tauchen von Eisen- oder Stahlbauteilen, umfasst.

The subject of the present invention is therefore the inventive use of a plant for hot-dip galvanizing iron or steel components, wherein the plant comprises the following treatment devices in the sequence listed below:

1. (A) at least one degreasing device for the degreasing treatment of iron or steel components; downstream or downstream of (A) in the process direction
2. (B) optionally at least one rinsing device for rinsing iron or steel components degreased in the degreasing device (A); downstream or downstream of (B) in the process direction
3. (C) at least one pickling device for the pickling treatment of iron or steel components degreased in the degreasing device (A) and optionally rinsed in the rinsing device (B); downstream or downstream of (C) in the process direction
4. (D) optionally at least one rinsing device for rinsing iron or steel components pickled in the pickling device (C); downstream or downstream of (D) in the process direction
5. (E) at least one flux treatment device for flux treatment of iron or steel components pickled in the pickling device (C) and optionally rinsed in the rinsing device (D), wherein the flux treatment device contains at least one flux bath with a flux composition,
   • wherein the flux bath comprises a liquid phase containing an alcohol/water mixture, wherein the liquid phase of the flux bath contains the flux composition, wherein the alcohol of the alcohol/water mixture of the flux bath is a water-miscible and/or a water-soluble alcohol and is selected from the group of linear or branched, saturated or unsaturated, aliphatic, cycloaliphatic or aromatic, primary, secondary or tertiary monohydric C ₁ -C ₄ alcohols and mixtures thereof, and
   • where the flux composition as ingredients
     1. (i) zinc chloride (ZnCl ₂ ) in amounts ranging from 50 to 95 wt.%,
     2. (ii) ammonium chloride (NH ₄ Cl) in amounts ranging from 5 to 45% by weight,
     3. (iii) at least one alkali and/or alkaline earth salt in amounts ranging from 0.1 to 25% by weight and
     4. (iv) at least one aluminium salt and/or at least one silver salt in amounts ranging from 5 • 10 ^-5 to 2 wt.%
   • all the above-mentioned quantities are based on the composition and are to be selected in such a way that a total of 100% by weight results,
     and
   • wherein the flux composition is completely free of lead chloride (PbCl ₂ ) and nickel chloride (NiCl ₂ );
   • downstream in the process direction or downstream of (E)
6. (F) at least one drying device (F) for drying iron or steel components subjected to flux treatment in the flux treatment device (E),
   • wherein the drying device (F) is controlled by means of a control device such that the drying treatment is carried out such that the surface of the iron or steel component has a temperature in the range of 100 to 300 °C during drying,
   • wherein the drying device (F) has at least one inlet for introducing and/or admitting air and
   • wherein the drying device (F) comprises at least one drying device;
   • downstream in the process direction or downstream of (F)
7. (G) at least one hot-dip galvanizing device for hot-dip galvanizing iron or steel components which have been subjected to flux treatment in the flux treatment device (E) and optionally dried in the drying device (F),
   wherein the hot-dip galvanizing device comprises at least one galvanizing bath containing an aluminum-containing zinc melt, designed for dipping iron or steel components.

As explained below, the present invention is associated with a multitude of completely unexpected advantages, special features and surprising technical effects, the following description of which makes no claim to completeness, but illustrates the inventive character of the present invention:
Surprisingly, within the scope of the present invention it is possible to use a flux, i.e. a flux bath or a flux composition, which even in the difficult-to-perform hot-dip galvanizing using aluminum-containing or aluminum-alloyed zinc melts does not require the presence of lead chloride (PbCl ₂ ) and nickel chloride (NiCl ₂ ) and preferably also dispenses with other transition metal chlorides in the flux, in particular in the flux bath or the flux composition, such as in particular cobalt chloride (CoCl ₂ ), manganese chloride (MnCl ₂ ), tin chloride (SnCl ₂ ), bismuth chloride (BiCl ₃ ) and antimony chloride (SbCl ₃ ), without impairing the quality of the resulting hot-dip galvanizing layer.

On the contrary, the present invention results in hot-dip galvanized layers that are completely free of defects and which also have improved corrosion protection properties and, in general, excellent, if not even improved, mechanical and other properties (e.g. optical properties such as gloss).

As explained below, a special feature of the present invention in this context is that the flux used according to the invention, in particular the flux composition used according to the invention or the flux bath used according to the invention, contains at least one aluminum salt and/or at least one silver salt, in particular aluminum chloride (AlCl ₃ ) and/or silver chloride (AgCl), preferably aluminum chloride (AlCl ₃ ), preferably in very small amounts, which means that organic and/or inorganic impurities (such as suspended matter), which are still present, for example, from the upstream treatment steps despite rinsing processes and generally lead to the formation of defects during hot-dip galvanizing, can be discharged or precipitated, so that additional transition metal chlorides to improve the wetting behavior or other properties in the context of the flux used according to the invention, in particular the flux bath or flux composition, can be completely dispensed with.

In combination with a liquid phase of the flux bath based on a water/alcohol mixture, the efficiency of the process used according to the invention can be further improved: As explained in more detail below, the effects of the alcohol content in the The times required for drying the flux film in the flux bath can be significantly shortened and/or the drying temperatures can be significantly reduced. In addition, the filming and wetting with the flux is homogenized in this way.

In particular, the present invention, with regard to hot-dip galvanizing using aluminum-alloyed or aluminum-containing zinc melts, brings about significantly improved process economy and a more efficient, in particular more flexible and/or more reliable, in particular less error-prone process sequence as well as improved ecological compatibility, in particular due to the omission of lead chloride and nickel chloride and possibly other transition or heavy metal chlorides in the flux used, but also the alcohol content in the flux bath.

Consequently, the present invention, particularly due to its improved ecological compatibility, can also be used in ecologically sensitive areas where transition and heavy metal compounds, in particular transition metal and heavy metal chlorides, are to be avoided.

In particular, the present invention does not require the use of significant amounts of transition and heavy metal compounds, in particular transition and heavy metal chlorides, such as lead and/or nickel chloride, but possibly also other heavy metal chlorides, such as cobalt, manganese, tin, antimony and/or bismuth chloride, in the context of the flux treatment, but nevertheless reliably ensures that the treated components are galvanized efficiently and without defects.

The special features of the use according to the invention or of the system used according to the invention described below are also reflected directly in the process products that can be obtained, ie the hot-dip galvanized or hot-dip galvanized iron and steel components: These not only have improved mechanical and optical properties and improved corrosion protection properties, but are also completely free of defects, and this with relatively low layer thicknesses in relation to the hot-dip galvanized layer. In addition, no undesirable transition metals or heavy metals can be introduced from the flux into the ultimately resulting hot-dip galvanized layer, since transition metals or heavy metals can be completely avoided during the flux treatment according to the present invention.

Transition metals or heavy metals are at most deliberately added or alloyed to the zinc melt or the hot-dip galvanizing bath in order to specifically adjust certain properties of the hot-dip galvanizing layer, but then in an ecologically compatible manner, since they are an integral part of the hot-dip galvanizing layer and are stored or incorporated therein as a solid alloy component.

The individual ingredients or components of the flux composition used according to the invention and of the flux bath used according to the invention work together in a synergistic manner: The zinc chloride ensures very good coverage of the iron or steel surface, particularly due to the flat formation of the dried ZnCl ₂ crystals. However, since 100% coverage is practically impossible to achieve and smaller oxidation sites or a thin oxidation layer can always be present, a sufficient amount of ammonium chloride is also added to the flux composition, which is deposited on the component surface and thermally decomposes to NH ₃ and HCl at the moment of immersion in the zinc melt, so that the last oxide residues are removed from the component surface. Since an excessively increased NH ₄ Cl content causes the melting point of the ZnCl ₂ /NH ₄ Cl mixture to drop significantly compared to pure zinc chloride (approx. 300 °C), alkali and/or alkaline earth salts, in particular NaCl and/or KCl, are added, which raise the melting point of the flux composition and thus enable high and effective drying.

In addition, it has now surprisingly been shown that the use of silver or aluminum salt, in particular AgCl and/or AlCl ₃ , in the flux or flux composition leads to an increase in the purity of the flux or flux composition, since silver or aluminum salt, in particular AgCl and/or AlCl ₃ , namely organic and/or inorganic impurities, such as suspended matter, which can be introduced from the upstream pretreatment steps despite repeated rinsing processes, are removed or precipitated in small quantities, but in Zn/Al melts in quantities large enough to form defects. Examples of such impurities are germs or bacteria (e.g. carryover from degreasing) and phosphates and sulfates (e.g. carryover from pickling). The precipitation of these substances prevents transfer to the component surface and thus eliminates the source of incorrect galvanizing.

Furthermore, it has been shown that the use of alcohol in the flux bath as at least a partial replacement for the otherwise commonly used pure water base has a positive effect on the process control and the galvanizing result in several respects.

The alcohol content allows even the smallest impurities to be dissolved in the flux (which, in the case of organic substances, are then precipitated by the aluminum or silver salt used, in particular AlCl ₃ and/or AgCl), so that an improved cleaning effect is achieved.

The alcohol content can shorten the time required to dry the flux film, particularly due to the lower evaporation point of alcohol compared to water. This leads to a significant improvement over the previous state of the art, in which the galvanizing cycle defines the maximum drying time and as a result, particularly with massive components, the drying time is often not sufficient to dry the flux film sufficiently. A completely dried flux film enables a clean reaction with the zinc melt without splashing due to evaporating residual water. Better drying also leads to less zinc ash, which reduces the risk of zinc ash adhering to the galvanized material (i.e. better galvanizing quality and less rework). Faster drying also means that the drying time and/or drying temperature can be reduced, which in turn means energy savings and/or an increase in productivity. The flux in the zinc bath also burns off more quickly (also due to the lower evaporation point), i.e. the energy of the zinc melt can flow directly into heating the component, which in turn leads to a faster and more effective galvanizing process.

The proportion of alcohol used depends in particular on the aluminium content of the zinc melt used, on the required drying or preheating (which in turn depends on the component geometry, in particular the material thickness, whereby thicker components require longer drying times), on the zinc alloy used and on the thickness of the flux film applied, whereby thicker flux layers depend on the salt concentration, extraction speed, roughness of the steel surface, etc., require longer drying times), the degree of contamination of the material to be galvanized and the technical requirements of the plant (e.g. performance of the drying oven, timing of the galvanizing process, suction performance of the flux bath, etc.).

As a result, under the same drying conditions (i.e. the same drying times and drying temperatures), the use of alcohol in the flux bath leads to faster drying of the flux film and to better galvanizing quality, even at low and high levels. This means that better drying leads to better galvanizing quality. In corrosion tests (e.g. salt spray test or salt spray test according to DIN EN ISO 9227:2012), hot-dip galvanized components pretreated with an alcohol-containing flux also show significantly longer service lives (up to 20% improvement in service life and even more) compared to hot-dip galvanized components pretreated with an otherwise identical flux (but without any alcohol content, i.e. purely aqueous).

Within the scope of the present invention, an efficient and ecologically compatible hot-dip galvanizing process can thus be provided, whereby the disadvantages of the prior art described above can be at least largely avoided or at least mitigated.

In the following, preferred embodiments of the use according to the invention or of the process sequence used according to the invention are described and explained in more detail:
According to the present invention, the flux bath is adjusted to a defined and/or predetermined, in particular acidic pH value, in particular in the pH value range from 0 to 6.9, preferably in the pH value range from 0.5 to 6.5, preferably in the pH value range from 1 to 5.5, particularly preferably in the pH value range from 1.5 to 5, very particularly preferably in the pH value range from 2 to 4.5, even more preferably in the pH value range from 2 to 4.

According to a particularly preferred embodiment, the flux bath is adjusted to a defined and/or predetermined, in particular acidic pH value, wherein the pH value is adjusted using a preferably inorganic acid in combination with a preferably inorganic basic compound, in particular ammonia (NH ₃ ). This embodiment, ie the fine adjustment of the pH value using a preferably inorganic basic compound, in particular ammonia (NH ₃ ), is particularly advantageous because it counteracts undesirable hydrogen embrittlement of the component to be treated.

As regards the flux bath used according to the invention, in particular the alcohol/water mixture of the liquid phase of the flux bath, the weight-related alcohol/water ratio can vary within wide ranges. In general, the flux bath contains the alcohol/water mixture in a weight-related alcohol/water ratio in the range from 0.5:99.5 to 99:1, in particular in the range from 2:98 to 95:5, preferably in the range from 5:95 to 90:10, preferably in the range from 5:95 to 50:50, particularly preferably in the range from 5:95 to 45:55, very particularly preferably in the range from 5:95 to 50:50, even more preferably in the range from 10:90 to 30:70, based on the alcohol/water mixture.

According to a particular embodiment, the flux bath contains the alcohol, based on the alcohol/water mixture, in an amount of at least 0.5 wt.%, in particular in an amount of at least 1 wt.%, preferably in an amount of at least 2 wt.%, particularly preferably in an amount of at least 3 wt.%, even more preferably in an amount of at least 4 wt.%.

Typically, the flux bath contains the alcohol, based on the alcohol/water mixture, in an amount of up to 90 wt.%, in particular in an amount of up to 70 wt.%, preferably in an amount of up to 50 wt.%, particularly preferably in an amount of up to 30 wt.%, even more preferably in an amount of up to 25 wt.%.

According to the invention, the alcohol of the alcohol/water mixture of the flux bath is a water-miscible and/or water-soluble alcohol.

Advantageously, the alcohol of the alcohol/water mixture of the flux bath is an alcohol that forms an azeotropic mixture with water.

According to the invention, the alcohol of the alcohol/water mixture of the flux bath is selected from the group of C ₁ -C ₄ alcohols and mixtures thereof.

According to the invention, the alcohol of the alcohol/water mixture of the flux bath is selected from the group of linear or branched, saturated or unsaturated, aliphatic, cycloaliphatic or aromatic, primary, secondary or tertiary monohydric C ₁ -C ₄ alcohols.

According to a particularly preferred embodiment, the alcohol of the alcohol/water mixture of the flux bath is selected from the group of methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol and mixtures thereof.

As regards the flux bath used according to the invention, the flux bath can - in addition to the ingredients or components mentioned above - also contain at least one wetting agent and/or surfactant, in particular at least one ionic or non-ionic wetting agent and/or surfactant, preferably at least one non-ionic wetting agent and/or surfactant.

The amounts of the wetting agent and/or surfactant in question can vary widely:
In particular, the flux bath can contain the at least one wetting agent and/or surfactant in amounts of 0.0001 to 15 wt.%, preferably in amounts of 0.001 to 10 wt.%, preferably in amounts of 0.01 to 8 wt.%, even more preferably in amounts of 0.01 to 6 wt.%, very particularly preferably in amounts of 0.05 to 3 wt.%, even more preferably in amounts of 0.1 to 2 wt.%, based on the flux bath.

Furthermore, the flux can contain the at least one wetting agent and/or surfactant in particular in amounts of 0.0001 to 10 vol.%, preferably in amounts of 0.001 to 8 vol.%, preferably in amounts of 0.01 to 5 vol.%, even more preferably in amounts of 0.01 to 5 vol.%, very particularly preferably in amounts of 0.05 to 3 vol.%, even more preferably in amounts of 0.1 to 2 vol.%, based on the flux bath.

The amount or concentration of the flux composition used according to the invention in the flux bath used according to the invention can equally vary within wide ranges:
Typically, the flux bath may contain the flux composition in an amount of at least 150 g/l, in particular in an amount of at least 200 g/l, preferably in an amount of at least 250 g/l, preferably in an amount of at least 300 g/l, particularly preferably in an amount of at least 400 g/l, very particularly preferably in an amount of at least 450 g/l, even more preferably in an amount of at least 500 g/l, in particular calculated as the total salt content of the flux composition.

Preferably, the flux bath can contain the flux composition in an amount of 150 g/l to 750 g/l, in particular in an amount of 200 g/l to 700 g/l, preferably in an amount of 250 g/l to 650 g/l, preferably in an amount of 300 g/l to 625 g/l, particularly preferably in an amount of 400 g/l to 600 g/l, very particularly preferably in an amount of 450 g/l to 580 g/l, even more preferably in an amount of 500 g/l to 575 g/l, in particular calculated as the total salt content of the flux composition.

1. (i) Zinkchlorid (ZnCl₂) in Mengen im Bereich von 50 bis 95 Gew.-%, vorzugsweise im Bereich von 55 bis 90 Gew.-%, bevorzugt im Bereich von 60 bis 85 Gew.-%, besonders bevorzugt im Bereich von 65 bis 82,5 Gew.-%, noch mehr bevorzugt im Bereich von 70 bis 82 Gew.-%,
2. (ii) Ammoniumchlorid (NH₄Cl) in Mengen im Bereich von 5 bis 45 Gew.-%, vorzugsweise im Bereich von 7,5 bis 40 Gew.-%, bevorzugt im Bereich von 10 bis 35 Gew.-%, besonders bevorzugt im Bereich von 11 bis 25 Gew.-%, noch mehr bevorzugt im Bereich von 12 bis 20 Gew.-%,
3. (iii) mindestens ein Alkali- und/oder Erdalkalisalz in Mengen im Bereich von 0,1 bis 25 Gew.-%, vorzugsweise im Bereich von 0,5 bis 20 Gew.-%, bevorzugt im Bereich von 1 bis 15 Gew.-%, besonders bevorzugt im Bereich von 2 bis 12,5 Gew.-%, noch mehr bevorzugt im Bereich von 4 bis 10 Gew.-%, und
4. (iv) mindestens ein Aluminiumsalz und/oder mindestens ein Silbersalz, insbesondere Aluminiumchlorid (AlCl₃) und/oder Silberchlorid (AgCI), vorzugsweise Aluminiumchlorid (AlCl₃), in Mengen im Bereich von 5 • 10^-5 bis 2 Gew.-%, noch mehr bevorzugt im Bereich von 5 • 10^-5 bis 5 • 10^-3 Gew.-%,

wobei alle vorgenannten Mengenangaben auf die Zusammensetzung bezogen sind und derart auszuwählen sind, dass insgesamt 100 Gew.-% resultieren, und wobei die Flussmittelzusammensetzung zumindest im Wesentlichen frei, vorzugsweise vollkommen frei, von Bleichlorid (PbCl₂) und Nickelchlorid (NiCl₂) ausgebildet ist.As regards the flux composition used according to the invention as such, the flux composition contains as ingredients

1. (i) zinc chloride (ZnCl ₂ ) in amounts ranging from 50 to 95% by weight, preferably from 55 to 90% by weight, more preferably from 60 to 85% by weight, particularly preferably from 65 to 82.5% by weight, even more preferably from 70 to 82% by weight,
2. (ii) ammonium chloride (NH ₄ Cl) in amounts ranging from 5 to 45% by weight, preferably ranging from 7.5 to 40% by weight, preferably ranging from 10 to 35% by weight, particularly preferably ranging from 11 to 25% by weight, even more preferably ranging from 12 to 20% by weight,
3. (iii) at least one alkali and/or alkaline earth salt in amounts in the range of 0.1 to 25% by weight, preferably in the range of 0.5 to 20% by weight, preferably in the range of 1 to 15% by weight, particularly preferably in the range of 2 to 12.5% by weight, even more preferably in the range of 4 to 10% by weight, and
4. (iv) at least one aluminium salt and/or at least one silver salt, in particular aluminium chloride (AlCl ₃ ) and/or silver chloride (AgCl), preferably aluminium chloride (AlCl ₃ ), in amounts in the range from 5 • 10 ^-5 to 2% by weight, even more preferably in the range from 5 • 10 ^-5 to 5 • 10 ^-3 % by weight,

wherein all the above-mentioned quantities are related to the composition and are to be selected such that a total of 100 wt.% results, and wherein the flux composition is at least substantially free, preferably completely free, of lead chloride (PbCl ₂ ) and nickel chloride (NiCl ₂ ).

As regards component (iii), ie the alkaline earth metal and/or alkaline earth metal salt, of the flux composition used according to the invention, there are also various possible variations:
In particular, the flux composition used according to the invention can contain an alkali and/or alkaline earth chloride as the alkali and/or alkaline earth salt of component (iii).

Furthermore, the flux composition used according to the invention can contain as alkali and/or alkaline earth salt of component (iii) at least one alkali and/or alkaline earth salt of an alkali and/or alkaline earth metal from the group of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) and combinations thereof.

According to the invention, it is preferred if the flux composition used according to the invention contains, as the alkali and/or alkaline earth salt of component (iii), at least two alkali and/or alkaline earth salts that are different from one another, in particular at least two alkali and/or alkaline earth salts of an alkali and/or alkaline earth metal from the group of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) and combinations thereof.

Furthermore, it is particularly preferred if the flux composition used according to the invention contains, as alkali and/or alkaline earth salt of component (iii), at least two different alkali salts, in particular two different alkali chlorides, preferably sodium chloride and potassium chloride, in particular with a sodium/potassium weight ratio in the range from 50:1 to 1:50, in particular in the range from 25:1 to 1:25, preferably in the range from 10:1 to 1:10.

According to the invention, it is particularly preferred if the flux composition used according to the invention is also completely free of cobalt chloride (CoCl ₂ ), manganese chloride (MnCl ₂ ), tin chloride (SnCl ₂ ), bismuth chloride (BiCl ₃ ) and antimony chloride (SbCl ₃ ).

According to the invention, it is also preferred if the flux composition used according to the invention is completely free of lead chloride (PbCl ₂ ), nickel chloride (NiCl ₂ ), cobalt chloride (CoCl ₂ ), manganese chloride (MnCl ₂ ), tin chloride (SnCl ₂ ), bismuth chloride (BiCl ₃ ) and antimony chloride (SbCl ₃ ) and/or if the flux composition is at least completely free of chlorides from the group of lead chloride (PbCl ₂ ), nickel chloride (NiCl ₂ ), cobalt chloride (CoCl ₂ ), manganese chloride (MnCl ₂ ), tin chloride (SnCl ₂ ), bismuth chloride (BiCl ₃ ) and antimony chloride (SbCl ₃ ).

It is further advantageous according to the invention if the flux composition used according to the invention is completely free of salts and compounds of metals from the group of lead (Pb), nickel (Ni), cobalt (Co), manganese (Mn), tin (Sn), bismuth (Bi) and antimony (Sb).

Finally, it is also advantageous according to the invention if the flux composition used according to the invention, apart from zinc chloride (ZnCl ₂ ) and aluminum and/or silver salt, in particular silver chloride (AgCl) and/or aluminum chloride (AlCl ₃ ), is completely free of salts and compounds of transition and heavy metals.

As far as the flux treatment is concerned, the general procedure is that the flux treatment is carried out by bringing the iron or steel component into contact with the flux bath and/or the flux composition, in particular by dipping or spraying, preferably dipping. In particular, it is advantageous if the iron or steel component is brought into contact with the flux bath and/or the flux composition, in particular dipped into the flux bath, for a period of 0.001 to 30 minutes, in particular 0.01 to 20 minutes, preferably 0.1 to 15 minutes, preferably 0.5 to 10 minutes, particularly preferably 1 to 5 minutes. In particular, the iron or steel component can be brought into contact with the flux bath and/or the flux composition, in particular dipped into the flux bath, for a period of up to 30 minutes, in particular up to 20 minutes, preferably up to 15 minutes, preferably up to 10 minutes, particularly preferably up to 5 minutes.

As far as the drying treatment is concerned, it is preferred according to the invention if the drying treatment is carried out at a temperature in the range from 50 to 400 °C, in particular in the range from 75 to 350 °C, preferably in the range from 100 to 300 °C, preferably in the range from 125 to 275 °C, particularly preferably in the range from 150 to 250 °C, and/or if the drying treatment is carried out at a temperature up to 400 °C, in particular up to 350 °C, preferably up to 300 °C, preferably up to 275 °C, particularly preferably up to 250 °C.

Usually, the drying treatment is carried out in such a way that the surface of the iron or steel component has a temperature in the range of 100 to 300 °C, in particular in the range of 125 to 275 °C, preferably in the range of 150 to 250 °C, preferably in the range of 160 to 225 °C, particularly preferably in the range of 170 to 200 °C, during drying.

Typically, the drying treatment can be carried out in the presence of and/or by means of air.

In particular, the drying treatment can be carried out in at least one drying device, in particular in at least one oven.

As regards the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath used according to the invention, the following must be stated in this regard.

According to a typical embodiment of the present invention, it is advantageous if the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath has an amount of aluminum in the range from 0.0001 to 25 wt.%, in particular in the range from 0.001 to 20 wt.%, preferably in the range from 0.005 to 17.5 wt.%, preferably in the range from 0.01 to 15 wt.%, particularly preferably in the range from 0.02 to 12.5 wt.%, very particularly preferably in the range from 0.05 to 10 wt.%, even more preferably in the range from 0.1 to 8 wt.%, based on the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath. In particular, the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath, based on the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath, can have an amount of zinc of at least 75 wt.%, in particular at least 80 wt.%, preferably at least 85 wt.%, preferably at least 90 wt.%, and optionally at least one further metal, in particular in amounts of up to 5 wt.% and/or in particular selected from the group of bismuth (Bi), lead (Pb), tin (Sn), nickel (Ni), silicon (Si), magnesium (Mg) and combinations thereof. All of the above-mentioned quantities are to be selected in such a way that a total of 100 wt.% results.

1. (i) Zink (Zn), insbesondere in Mengen im Bereich von 75 bis 99,9999 Gew.-%, insbesondere im Bereich von 80 bis 99,999 Gew.-%, vorzugsweise im Bereich von 82,5 bis 99,995 Gew.-%, bevorzugt im Bereich von 85 bis 99,99 Gew.-%, besonders bevorzugt im Bereich von 87,5 bis 99,98 Gew.-%, ganz besonders bevorzugt im Bereich von 90 bis 99,95 Gew.-%, noch mehr bevorzugt im Bereich von 92 bis 99,9 Gew.-%,
2. (ii) Aluminium (Al), insbesondere in Mengen im Bereich von 0,0001 bis 25 Gew.-%, insbesondere im Bereich von 0,001 bis 20 Gew.-%, vorzugsweise im Bereich von 0,005 bis 17,5 Gew.-%, bevorzugt im Bereich von 0,01 bis 15 Gew.-%, besonders bevorzugt im Bereich von 0,02 bis 12,5 Gew.-%, ganz besonders bevorzugt im Bereich von 0,05 bis 10 Gew.-%, noch mehr bevorzugt im Bereich von 0,1 bis 8 Gew.-%,
3. (iii) gegebenenfalls Bismut (Bi), insbesondere in Mengen von bis zu 0,5 Gew.-%, vorzugsweise in Mengen von bis zu 0,3 Gew.-%, bevorzugt in Mengen von bis zu 0,1 Gew.-%,
4. (iv) gegebenenfalls Blei (Pb), insbesondere in Mengen von bis zu 0,5 Gew.-%, vorzugsweise in Mengen von bis zu 0,2 Gew.-%, bevorzugt in Mengen von bis zu 0,1 Gew.-%,
5. (v) gegebenenfalls Zinn (Sn), insbesondere in Mengen von bis zu 0,9 Gew.-%, vorzugsweise in Mengen von bis zu 0,6 Gew.-%, bevorzugt in Mengen von bis zu 0,3 Gew.-%,
6. (vi) gegebenenfalls Nickel (Ni), insbesondere in Mengen von bis zu 0,1 Gew.-%, vorzugsweise in Mengen von bis zu 0,08 Gew.-%, bevorzugt in Mengen von bis zu 0,06 Gew.-%,
7. (vii) gegebenenfalls Silizium (Si), insbesondere in Mengen von bis zu 0,1 Gew.-%, vorzugsweise in Mengen von bis zu 0,05 Gew.-%, bevorzugt in Mengen von bis zu 0,01 Gew.-%,
8. (viii) gegebenenfalls Magnesium (Mg), insbesondere in Mengen von bis zu 5 Gew.-%, vorzugsweise in Mengen von bis zu 2,5 Gew.-%, bevorzugt in Mengen von bis zu 0,8 Gew.-%.

Furthermore, it is preferred according to the invention if the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath has the following composition, wherein all the quantities given below relate to the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath and are to be selected in such a way that a total of 100% by weight results:

1. (i) zinc (Zn), in particular in amounts in the range from 75 to 99.9999 wt.%, in particular in the range from 80 to 99.999 wt.%, preferably in the range from 82.5 to 99.995 wt.%, preferably in the range from 85 to 99.99 wt.%, particularly preferably in the range from 87.5 to 99.98 wt.%, very particularly preferably in the range from 90 to 99.95 wt.%, even more preferably in the range from 92 to 99.9 wt.%,
2. (ii) aluminium (Al), in particular in amounts in the range from 0.0001 to 25% by weight, in particular in the range from 0.001 to 20% by weight, preferably in the range from 0.005 to 17.5% by weight, preferably in the range from 0.01 to 15% by weight, particularly preferably in the range from 0.02 to 12.5% by weight, very particularly preferably in the range from 0.05 to 10% by weight, even more preferably in the range from 0.1 to 8% by weight,
3. (iii) optionally bismuth (Bi), in particular in amounts of up to 0.5% by weight, preferably in amounts of up to 0.3% by weight, preferably in amounts of up to 0.1% by weight,
4. (iv) optionally lead (Pb), in particular in amounts of up to 0.5 wt.%, preferably in amounts of up to 0.2 wt.%, preferably in amounts of up to 0.1 wt.%,
5. (v) optionally tin (Sn), in particular in amounts of up to 0.9 wt.%, preferably in amounts of up to 0.6 wt.%, preferably in amounts of up to 0.3 wt.%,
6. (vi) optionally nickel (Ni), in particular in amounts of up to 0.1% by weight, preferably in amounts of up to 0.08% by weight, preferably in amounts of up to 0.06% by weight,
7. (vii) optionally silicon (Si), in particular in amounts of up to 0.1 wt.%, preferably in amounts of up to 0.05 wt.%, preferably in amounts of up to 0.01 wt.%,
8. (viii) optionally magnesium (Mg), in particular in amounts of up to 5 wt.%, preferably in amounts of up to 2.5 wt.%, preferably in amounts of up to 0.8 wt.%.

If the zinc melt used contains other alloy components or alloy metals in addition to aluminum, this can be used to specifically control the process: The presence of lead and bismuth in particular can reduce the surface tension and thus improve the wettability of the surface to be galvanized, while the presence of tin can improve the optical properties, in particular the gloss, of the resulting galvanizing layer, the presence of nickel can further reduce the layer thickness, the presence of silicon can extend the service life of the zinc bath container (e.g. steel kettle), and the presence of magnesium can improve the corrosion properties, in particular the corrosion resistance, of the resulting galvanizing layer.

According to a particular embodiment, the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath can have a temperature in the range from 375 °C to 750 °C, in particular a temperature in the range from 380 °C to 700 °C, preferably a temperature in the range from 390 °C to 680 °C, even more preferably in the range from 395 °C to 675 °C.

Typically, the hot-dip galvanizing step is carried out in such a way that the iron or steel component is dipped into the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or into the galvanizing bath, in particular dipped therein and moved, in particular for a period of time which is sufficient to ensure effective hot-dip galvanizing (hot-dip galvanizing), in particular for a period of time in the range of 0.0001 to 60 minutes, preferably in the range of 0.001 to 45 minutes, preferably in the range of 0.01 to 30 minutes, even more preferably in the range of 0.1 to 15 minutes.

In particular, the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath can be contacted with and/or flushed or passed through at least one inert gas, in particular nitrogen.

In principle, the process used in the context of the use according to the invention can be operated continuously or discontinuously.

The iron or steel component to be treated may be a single product or a large number of individual products. In this case, a discontinuous process is preferred, although a continuous process is not excluded in principle.

Furthermore, the iron or steel component can also be a long product, in particular a wire, pipe, sheet, coil material or the like. In this case, a continuous procedure is preferred, although a discontinuous procedure is not excluded in this respect either.

According to a particular embodiment of the present invention, the hot-dip galvanizing (hot-dip galvanizing) carried out can be followed by a cooling step, i.e. the hot-dip galvanized (hot-dip galvanized) iron or steel component can be subjected to a cooling treatment, optionally followed by a further post-processing and/or post-treatment step.

The optional cooling step and/or the optional cooling treatment can in particular be carried out by means of air and/or in the presence of air, preferably to ambient temperature.

1. (A) mindestens eine Entfettungsvorrichtung zur Entfettungsbehandlung von Eisen- oder Stahlbauteilen; in Prozessrichtung nachgeschaltet oder stromabwärts zu (A)
2. (B) gegebenenfalls mindestens eine Spülvorrichtung zum Spülen von in der Entfettungsvorrichtung (A) entfetteten Eisen- oder Stahlbauteilen; in Prozessrichtung nachgeschaltet oder stromabwärts zu (B)
3. (C) mindestens eine Beizvorrichtung zur Beizbehandlung von in der Entfettungsvorrichtung (A) entfetteten und gegebenenfalls in der Spülvorrichtung (B) gespülten Eisen- oder Stahlbauteilen; in Prozessrichtung nachgeschaltet oder stromabwärts zu (C)
4. (D) gegebenenfalls mindestens eine Spülvorrichtung zum Spülen von in der Beizvorrichtung (C) gebeizten Eisen- oder Stahlbauteilen; in Prozessrichtung nachgeschaltet oder stromabwärts zu (D)
5. (E) mindestens eine Flussmittelbehandlungsvorrichtung zur Flussmittelbehandlung von in der Beizvorrichtung (C) gebeizten und gegebenenfalls in der Spülvorrichtung (D) gespülten Eisen- oder Stahlbauteilen, wobei die Flussmittelbehandlungsvorrichtung mindestens ein Flussmittelbad mit einer Flussmittelzusammensetzung enthält,
   • wobei das Flussmittelbad eine ein Alkohol/Wasser-Gemisch enthaltende flüssige Phase umfasst, wobei die flüssige Phase des Flussmittelbades die Flussmittelzusammensetzung enthält, wobei der Alkohol des Alkohol/Wasser-Gemischs des Flussmittelbades ein mit Wasser mischbarer und/oder ein in Wasser löslicher Alkohol ist und ausgewählt ist aus der Gruppe von linearen oder verzweigten, gesättigten oder ungesättigten, aliphatischen, cycloaliphatischen oder aromatischen, primären, sekundären oder tertiären einwertigen C₁-C₄-Alkoholen und deren Mischungen, und
   • wobei die Flussmittelzusammensetzung als Inhaltsstoffe
     1. (i) Zinkchlorid (ZnCl₂) in Mengen im Bereich von 50 bis 95 Gew.-%,
     2. (ii) Ammoniumchlorid (NH₄Cl) in Mengen im Bereich von 5 bis 45 Gew.-%,
     3. (iii) mindestens ein Alkali- und/oder Erdalkalisalz in Mengen im Bereich von 0,1 bis 25 Gew.-% und
     4. (iv) mindestens ein Aluminiumsalz und/oder mindestens ein Silbersalz in Mengen im Bereich von 5 • 10^-5 bis 2 Gew.-%
   • enthält, wobei alle vorgenannten Mengenangaben auf die Zusammensetzung bezogen sind und derart auszuwählen sind, dass insgesamt 100 Gew.-% resultieren,
     und
   • wobei die Flussmittelzusammensetzung vollkommen frei von Bleichlorid (PbCl₂) und Nickelchlorid (NiCl₂) ausgebildet ist;
   • in Prozessrichtung nachgeschaltet oder stromabwärts zu (E)
6. (F) mindestens eine Trocknungsvorrichtung (F) zur Trocknung von in der Flussmittelbehandlungsvorrichtung (E) einer Flussmittelbehandlung unterzogenen Eisen- oder Stahlbauteilen,
   • wobei die Trocknungsvorrichtung (F) mittels einer Steuerungseinrichtung derart gesteuert wird, dass die Trocknungsbehandlung derart durchgeführt wird, dass die Oberfläche des Eisen- oder Stahlbauteils bei der Trocknung eine Temperatur im Bereich von 100 bis 300 °C aufweist,
   • wobei die Trocknungsvorrichtung (F) mindestens einen Einlass zum Einführen und/oder Einlassen von Luft aufweist und
   • wobei die Trocknungsvorrichtung (F) mindestens eine Trocknungseinrichtung umfasst;
   • in Prozessrichtung nachgeschaltet oder stromabwärts zu (F)
7. (G) mindestens eine Feuerverzinkungsvorrichtung zur Feuerverzinkung von in der Flussmittelbehandlungsvorrichtung (E) einer Flussmittelbehandlung unterzogenen und gegebenenfalls in der Trocknungsvorrichtung (F) getrockneten Eisen- oder Stahlbauteilen,
   wobei die Feuerverzinkungsvorrichtung mindestens ein eine aluminiumhaltige Zinkschmelze enthaltendes Verzinkungsbad, ausgebildet zum Tauchen von Eisen- oder Stahlbauteilen, umfasst.

As previously stated, the subject matter of the present invention is therefore the inventive use of a plant for hot-dip galvanizing iron or steel components,
the plant comprising the following treatment devices in the sequence listed below:

1. (A) at least one degreasing device for the degreasing treatment of iron or steel components; downstream or downstream of (A) in the process direction
2. (B) optionally at least one rinsing device for rinsing iron or steel components degreased in the degreasing device (A); downstream or downstream of (B) in the process direction
3. (C) at least one pickling device for the pickling treatment of iron or steel components degreased in the degreasing device (A) and optionally rinsed in the rinsing device (B); downstream in the process direction or downstream of (C)
4. (D) optionally at least one rinsing device for rinsing iron or steel components pickled in the pickling device (C); downstream or downstream of (D) in the process direction
5. (E) at least one flux treatment device for flux treatment of iron or steel components pickled in the pickling device (C) and optionally rinsed in the rinsing device (D), wherein the flux treatment device contains at least one flux bath with a flux composition,
   • wherein the flux bath comprises a liquid phase containing an alcohol/water mixture, wherein the liquid phase of the flux bath contains the flux composition, wherein the alcohol of the alcohol/water mixture of the flux bath is a water-miscible and/or a water-soluble alcohol and is selected from the group of linear or branched, saturated or unsaturated, aliphatic, cycloaliphatic or aromatic, primary, secondary or tertiary monohydric C ₁ -C ₄ alcohols and mixtures thereof, and
   • where the flux composition as ingredients
     1. (i) zinc chloride (ZnCl ₂ ) in amounts ranging from 50 to 95 wt.%,
     2. (ii) ammonium chloride (NH ₄ Cl) in amounts ranging from 5 to 45% by weight,
     3. (iii) at least one alkali and/or alkaline earth salt in amounts ranging from 0.1 to 25% by weight and
     4. (iv) at least one aluminium salt and/or at least one silver salt in amounts ranging from 5 • 10 ^-5 to 2 wt.%
   • all the above-mentioned quantities are based on the composition and are to be selected in such a way that a total of 100% by weight results,
     and
   • wherein the flux composition is completely free of lead chloride (PbCl ₂ ) and nickel chloride (NiCl ₂ );
   • downstream in the process direction or downstream of (E)
6. (F) at least one drying device (F) for drying iron or steel components subjected to flux treatment in the flux treatment device (E),
   • wherein the drying device (F) is controlled by means of a control device such that the drying treatment is carried out such that the surface of the iron or steel component has a temperature in the range of 100 to 300 °C during drying,
   • wherein the drying device (F) has at least one inlet for introducing and/or admitting air and
   • wherein the drying device (F) comprises at least one drying device;
   • downstream in the process direction or downstream of (F)
7. (G) at least one hot-dip galvanizing device for hot-dip galvanizing iron or steel components which have been subjected to flux treatment in the flux treatment device (E) and optionally dried in the drying device (F),
   wherein the hot-dip galvanizing device comprises at least one galvanizing bath containing an aluminum-containing zinc melt, designed for dipping iron or steel components.

As previously described, the flux bath of the flux treatment device (E) is usually acidic.

In particular, the flux bath is set to a defined and/or predetermined, in particular acidic pH value, in particular in the pH value range from 0 to 6.9, preferably in the pH value range from 0.5 to 6.5, preferably in the pH value range from 1 to 5.5, particularly preferably in the pH value range from 1.5 to 5, very particularly preferably in the pH value range from 2 to 4.5, even more preferably in the pH value range from 2 to 4.

According to a particularly preferred embodiment, the flux bath is adjusted to a defined and/or predetermined, in particular acidic pH value, the pH value being adjusted by means of a preferably inorganic acid in combination with a preferably inorganic basic compound, in particular ammonia (NH ₃ ). The associated advantages have already been explained in connection with the method used according to the invention.

As regards the flux bath used in the flux treatment device (E), its composition can vary within a wide range:
Typically, the system is designed such that the flux bath contains the alcohol/water mixture in a weight-related alcohol/water ratio in the range from 0.5:99.5 to 99:1, in particular in the range from 2:98 to 95:5, preferably in the range from 5:95 to 90:10, preferably in the range from 5:95 to 50:50, particularly preferably in the range from 5:95 to 45:55, very particularly preferably in the range from 5:95 to 50:50, even more preferably in the range from 10:90 to 30:70, based on the alcohol/water mixture.

Typically, the system used according to the invention is designed such that the flux bath contains the alcohol, based on the alcohol/water mixture, in an amount of at least 0.5 wt.%, in particular in an amount of at least 1 wt.%, preferably in an amount of at least 2 wt.%, particularly preferably in an amount of at least 3 wt.%, even more preferably in an amount of at least 4 wt.%.

Typically, the system used according to the invention is designed such that the flux bath contains the alcohol, based on the alcohol/water mixture, in an amount of up to 90 wt.%, in particular in an amount of up to 70 wt.%, preferably in an amount of up to 50 wt.%, particularly preferably in an amount of up to 30 wt.%, even more preferably in an amount of up to 25 wt.%.

According to the invention, the alcohol of the alcohol/water mixture of the flux bath is a water-miscible and/or water-soluble alcohol.

It is preferred if the alcohol of the alcohol/water mixture of the flux bath is an alcohol that forms an azeotropic mixture with water.

According to the invention, the alcohol of the alcohol/water mixture of the flux bath is selected from the group of linear or branched, saturated or unsaturated, aliphatic, cycloaliphatic or aromatic, primary, secondary or tertiary monohydric C ₁ -C ₄ alcohols.

According to a particularly preferred embodiment of the invention, the system is designed such that the alcohol of the alcohol/water mixture of the flux bath is selected from the group of methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol and mixtures thereof.

Within the scope of the system used according to the invention, it can be provided that the flux bath also contains at least one wetting agent and/or surfactant, in particular at least one ionic or non-ionic wetting agent and/or surfactant, preferably at least one non-ionic wetting agent and/or surfactant.

The amounts of wetting agent and/or surfactant in the flux bath used according to the invention can vary within wide ranges:
In particular, the flux bath can contain the at least one wetting agent and/or surfactant in amounts of 0.0001 to 15 wt.%, preferably in amounts of 0.001 to 10 wt.%, preferably in amounts of 0.01 to 8 wt.%, even more preferably in amounts of 0.01 to 6 wt.%, very particularly preferably in amounts of 0.05 to 3 wt.%, even more preferably in amounts of 0.1 to 2 wt.%, based on the flux bath.

Furthermore, the flux bath can contain the at least one wetting agent and/or surfactant in amounts of 0.0001 to 10 vol.%, preferably in amounts of 0.001 to 8 vol.%, preferably in amounts of 0.01 to 5 vol.%, even more preferably in amounts of 0.01 to 5 vol.%, very particularly preferably in amounts of 0.05 to 3 vol.%, even more preferably in amounts of 0.1 to 2 vol.%, based on the flux bath.

As previously explained in connection with the method used according to the invention, the amount or concentration of the flux composition used according to the invention in the flux bath designed according to the invention can equally vary within wide ranges:
In particular, it can be provided that the flux bath contains the flux composition in an amount of at least 150 g/l, in particular in an amount of at least 200 g/l, preferably in an amount of at least 250 g/l, preferably in an amount of at least 300 g/l, particularly preferably in an amount of at least 400 g/l, very particularly preferably in an amount of at least 450 g/l, even more preferably in an amount of at least 500 g/l, in particular calculated as the total salt content of the flux composition.

Furthermore, it can be provided according to the invention that the flux bath contains the flux composition in an amount of 150 g/l to 750 g/l, in particular in an amount of 200 g/l to 700 g/l, preferably in an amount of 250 g/l to 650 g/l, preferably in an amount of 300 g/l to 625 g/l, particularly preferably in an amount of 400 g/l to 600 g/l, very particularly preferably in an amount of 450 g/l to 580 g/l, even more preferably in an amount of 500 g/l to 575 g/l, in particular calculated as the total salt content of the flux composition.

1. (i) Zinkchlorid (ZnCl₂) in Mengen im Bereich von 50 bis 95 Gew.-%, vorzugsweise im Bereich von 55 bis 90 Gew.-%, bevorzugt im Bereich von 60 bis 85 Gew.-%, besonders bevorzugt im Bereich von 65 bis 82,5 Gew.-%, noch mehr bevorzugt im Bereich von 70 bis 82 Gew.-%,
2. (ii) Ammoniumchlorid (NH₄Cl) in Mengen im Bereich von 5 bis 45 Gew.-%, vorzugsweise im Bereich von 7,5 bis 40 Gew.-%, bevorzugt im Bereich von 10 bis 35 Gew.-%, besonders bevorzugt im Bereich von 11 bis 25 Gew.-%, noch mehr bevorzugt im Bereich von 12 bis 20 Gew.-%,
3. (iii) mindestens ein Alkali- und/oder Erdalkalisalz in Mengen im Bereich von 0,1 bis 25 Gew.-%, vorzugsweise im Bereich von 0,5 bis 20 Gew.-%, bevorzugt im Bereich von 1 bis 15 Gew.-%, besonders bevorzugt im Bereich von 2 bis 12,5 Gew.-%, noch mehr bevorzugt im Bereich von 4 bis 10 Gew.-%, und
4. (iv) mindestens ein Aluminiumsalz und/oder mindestens ein Silbersalz, insbesondere Aluminiumchlorid (AlCl₃) und/oder Silberchlorid (AgCI), vorzugsweise Aluminiumchlorid (AlCl₃), in Mengen im Bereich von 5 • 10^-5 bis 2 Gew.-%, noch mehr bevorzugt im Bereich von 5 • 10^-5 bis 5 • 10^-3 Gew.-%

• enthält, wobei alle vorgenannten Mengenangaben auf die Zusammensetzung bezogen sind und derart auszuwählen sind, dass insgesamt 100 Gew.-% resultieren, und
• wobei die Flussmittelzusammensetzung vollkommen frei von Bleichlorid (PbCl₂) und Nickelchlorid (NiCl₂) ausgebildet ist.

According to the invention, it is provided that the flux composition used according to the invention contains as ingredients

1. (i) zinc chloride (ZnCl ₂ ) in amounts ranging from 50 to 95% by weight, preferably from 55 to 90% by weight, more preferably from 60 to 85% by weight, particularly preferably from 65 to 82.5% by weight, even more preferably from 70 to 82% by weight,
2. (ii) ammonium chloride (NH ₄ Cl) in amounts ranging from 5 to 45% by weight, preferably ranging from 7.5 to 40% by weight, preferably ranging from 10 to 35% by weight, particularly preferably ranging from 11 to 25% by weight, even more preferably ranging from 12 to 20% by weight,
3. (iii) at least one alkali and/or alkaline earth salt in amounts in the range of 0.1 to 25% by weight, preferably in the range of 0.5 to 20% by weight, preferably in the range of 1 to 15% by weight, particularly preferably in the range of 2 to 12.5% by weight, even more preferably in the range of 4 to 10% by weight, and
4. (iv) at least one aluminium salt and/or at least one silver salt, in particular aluminium chloride (AlCl ₃ ) and/or silver chloride (AgCl), preferably aluminium chloride (AlCl ₃ ), in amounts in the range from 5 • 10 ^-5 to 2% by weight, even more preferably in the range from 5 • 10 ^-5 to 5 • 10 ^-3 % by weight

• all the above-mentioned amounts are based on the composition and are to be selected in such a way that a total of 100% by weight results, and
• The flux composition is completely free of lead chloride (PbCl ₂ ) and nickel chloride (NiCl ₂ ).

As already described above in connection with the process used according to the invention, component (iii) of the flux composition used according to the invention can also vary within wide ranges:
According to the invention, it is preferred if the flux composition contains an alkali metal and/or alkaline earth metal chloride as the alkali metal and/or alkaline earth metal salt of component (iii).

According to a typical embodiment, the flux composition used according to the invention can contain as alkali and/or alkaline earth salt of component (iii) at least one alkali and/or alkaline earth salt of an alkali and/or Alkaline earth metals from the group of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) as well as combinations.

According to another typical embodiment of the present invention, the flux composition used according to the invention can contain, as alkali and/or alkaline earth salt of component (iii), at least two different alkali and/or alkaline earth salts, in particular at least two alkali and/or alkaline earth salts of an alkali and/or alkaline earth metal from the group of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) and combinations thereof.

Finally, according to a typical embodiment, the flux composition used according to the invention can contain, as alkali and/or alkaline earth salt of component (iii), at least two different alkali salts, in particular two different alkali chlorides, preferably sodium chloride and potassium chloride, in particular with a sodium/potassium weight ratio in the range from 50:1 to 1:50, in particular in the range from 25:1 to 1:25, preferably in the range from 10:1 to 1:10.

According to the invention, it is preferred if the flux composition used according to the invention is also completely free of cobalt chloride (CoCl ₂ ), manganese chloride (MnCl ₂ ), tin chloride (SnCl ₂ ), bismuth chloride (BiCl ₃ ) and antimony chloride (SbCl ₃ ).

It is also advantageous according to the invention if the flux composition used according to the invention is completely free of lead chloride (PbCl ₂ ), nickel chloride (NiCl ₂ ), cobalt chloride (CoCl ₂ ), manganese chloride (MnCl ₂ ), tin chloride (SnCl ₂ ), bismuth chloride (BiCl ₃ ) and antimony chloride (SbCl ₃ ) and/or if the flux composition is completely free of chlorides from the group of lead chloride (PbCl ₂ ), nickel chloride (NiCl ₂ ), cobalt chloride (CoCl ₂ ), manganese chloride (MnCl ₂ ), tin chloride (SnCl ₂ ), bismuth chloride (BiCl ₃ ) and antimony chloride (SbCl ₃ ).

It is also preferred according to the invention if the flux composition used according to the invention is completely free of salts and compounds of metals from the group of lead (Pb), nickel (Ni), cobalt (Co), manganese (Mn), tin (Sn), bismuth (Bi) and antimony (Sb).

Finally, it is particularly advantageous according to the invention if the flux composition, apart from zinc chloride (ZnCl ₂ ) and aluminum and/or silver salt, in particular silver chloride (AgCl) and/or aluminum chloride (AlCl ₃ ), is completely free of salts and compounds of transition and heavy metals.

Furthermore, it can be provided according to the invention that the flux treatment device (E) comprises a device for bringing the iron or steel component into contact with the flux bath and/or the flux composition, in particular a device for dipping or spray application, preferably a device for dipping. In particular, it can be provided that the device for bringing the iron or steel component into contact with the flux bath and/or the flux composition can be controlled and/or is controlled in such a way, in particular by means of a control device, that the iron or steel component is brought into contact with the flux bath and/or the flux composition for a period of 0.001 to 30 minutes, in particular 0.01 to 20 minutes, preferably 0.1 to 15 minutes, preferably 0.5 to 10 minutes, particularly preferably 1 to 5 minutes, with the flux bath and/or the flux composition, in particular is dipped into the flux bath. Furthermore, it can be provided according to the invention in particular that the device for bringing the iron or steel component into contact with the flux bath and/or the flux composition is controllable and/or is controlled in such a way, in particular by means of a control device, that the iron or steel component is brought into contact with the flux bath and/or the flux composition for a period of up to 30 minutes, in particular up to 20 minutes, preferably up to 15 minutes, preferably up to 10 minutes, particularly preferably up to 5 minutes, in particular is immersed in the flux bath.

Furthermore, it is provided according to the invention that the drying device (F) is controllable and/or is controlled in such a way, in particular by means of a control device, that the drying treatment takes place at a temperature in the range of 100 to 300 °C, preferably in the range of 125 to 275 °C, particularly preferably in the range of 150 to 250 °C, and/or that the Drying treatment is carried out at a temperature of up to 300 °C, preferably up to 275 °C, particularly preferably up to 250 °C.

Furthermore, it is provided according to the invention that the drying device (F) can be controlled by means of a control device and/or is controlled in such a way that the drying treatment is carried out in such a way that the surface of the iron or steel component has a temperature in the range of 100 to 300 °C, in particular in the range of 125 to 275 °C, preferably in the range of 150 to 250 °C, preferably in the range of 160 to 225 °C, particularly preferably in the range of 170 to 200 °C, during drying.

Typically, the drying treatment is carried out in the presence of air. For this purpose, the drying device (F) has at least one inlet for introducing and/or admitting air.

According to the invention, the drying device (F) comprises at least one drying device, in particular at least one oven.

As regards the hot-dip galvanizing device (G) of the plant used according to the invention, it comprises at least one aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt"), in particular at least one galvanizing bath containing an aluminum-containing, in particular aluminum-alloyed zinc melt, preferably designed for dipping iron or steel components.

In this context, the system used according to the invention is typically designed such that the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath has an amount of aluminum in the range from 0.0001 to 25 wt. %, in particular in the range from 0.001 to 20 wt. %, preferably in the range from 0.005 to 17.5 wt. %, more preferably in the range from 0.01 to 15 wt. %, particularly preferably in the range from 0.02 to 12.5 wt. %, very particularly preferably in the range from 0.05 to 10 wt. %, even more preferably in the range from 0.1 to 8 wt. %, based on the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath, in particular wherein the aluminum-containing. In particular, the aluminium-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath, based on the aluminium-containing, in particular aluminium-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath, an amount of zinc of at least 75 wt. %, in particular at least 80 wt. %, preferably at least 85 wt. %, preferably at least 90 wt. %, and optionally at least one further metal, in particular in amounts of up to 5 wt. % and/or in particular selected from the group of bismuth (Bi), lead (Pb), tin (Sn), nickel (Ni), silicon (Si), magnesium (Mg) and combinations thereof. All of the above-mentioned quantities are to be selected such that a total of 100 wt. % results.

1. (i) Zink (Zn), insbesondere in Mengen im Bereich von 75 bis 99,9999 Gew.-%, insbesondere im Bereich von 80 bis 99,999 Gew.-%, vorzugsweise im Bereich von 82,5 bis 99,995 Gew.-%, bevorzugt im Bereich von 85 bis 99,99 Gew.-%, besonders bevorzugt im Bereich von 87,5 bis 99,98 Gew.-%, ganz besonders bevorzugt im Bereich von 90 bis 99,95 Gew.-%, noch mehr bevorzugt im Bereich von 92 bis 99,9 Gew.-%,
2. (ii) Aluminium (Al), insbesondere in Mengen im Bereich von 0,0001 bis 25 Gew.-%, insbesondere im Bereich von 0,001 bis 20 Gew.-%, vorzugsweise im Bereich von 0,005 bis 17,5 Gew.-%, bevorzugt im Bereich von 0,01 bis 15 Gew.-%, besonders bevorzugt im Bereich von 0,02 bis 12,5 Gew.-%, ganz besonders bevorzugt im Bereich von 0,05 bis 10 Gew.-%, noch mehr bevorzugt im Bereich von 0,1 bis 8 Gew.-%,
3. (iii) gegebenenfalls Bismut (Bi), insbesondere in Mengen von bis zu 0,5 Gew.-%, vorzugsweise in Mengen von bis zu 0,3 Gew.-%, bevorzugt in Mengen von bis zu 0,1 Gew.-%,
4. (iv) gegebenenfalls Blei (Pb), insbesondere in Mengen von bis zu 0,5 Gew.-%, vorzugsweise in Mengen von bis zu 0,2 Gew.-%, bevorzugt in Mengen von bis zu 0,1 Gew.-%,
5. (v) gegebenenfalls Zinn (Sn), insbesondere in Mengen von bis zu 0,9 Gew.-%, vorzugsweise in Mengen von bis zu 0,6 Gew.-%, bevorzugt in Mengen von bis zu 0,3 Gew.-%,
6. (vi) gegebenenfalls Nickel (Ni), insbesondere in Mengen von bis zu 0,1 Gew.-%, vorzugsweise in Mengen von bis zu 0,08 Gew.-%, bevorzugt in Mengen von bis zu 0,06 Gew.-%,
7. (vii) gegebenenfalls Silizium (Si), insbesondere in Mengen von bis zu 0,1 Gew.-%, vorzugsweise in Mengen von bis zu 0,05 Gew.-%, bevorzugt in Mengen von bis zu 0,01 Gew.-%,
8. (viii) gegebenenfalls Magnesium (Mg), insbesondere in Mengen von bis zu 5 Gew.-%, vorzugsweise in Mengen von bis zu 2,5 Gew.-%, bevorzugt in Mengen von bis zu 0,8 Gew.-%.

Typically, the plant used according to the invention is designed such that the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath has the following composition, whereby all the quantities given below relate to the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath and are to be selected such that a total of 100 wt.% results:

1. (i) zinc (Zn), in particular in amounts in the range from 75 to 99.9999 wt.%, in particular in the range from 80 to 99.999 wt.%, preferably in the range from 82.5 to 99.995 wt.%, preferably in the range from 85 to 99.99 wt.%, particularly preferably in the range from 87.5 to 99.98 wt.%, very particularly preferably in the range from 90 to 99.95 wt.%, even more preferably in the range from 92 to 99.9 wt.%,
2. (ii) aluminium (Al), in particular in amounts in the range from 0.0001 to 25% by weight, in particular in the range from 0.001 to 20% by weight, preferably in the range from 0.005 to 17.5% by weight, preferably in the range from 0.01 to 15% by weight, particularly preferably in the range from 0.02 to 12.5% by weight, very particularly preferably in the range from 0.05 to 10% by weight, even more preferably in the range from 0.1 to 8% by weight,
3. (iii) optionally bismuth (Bi), in particular in amounts of up to 0.5% by weight, preferably in amounts of up to 0.3% by weight, preferably in amounts of up to 0.1% by weight,
4. (iv) optionally lead (Pb), in particular in amounts of up to 0.5 wt.%, preferably in amounts of up to 0.2 wt.%, preferably in amounts of up to 0.1 wt.%,
5. (v) optionally tin (Sn), in particular in amounts of up to 0.9 wt.%, preferably in amounts of up to 0.6 wt.%, preferably in amounts of up to 0.3 wt.%,
6. (vi) optionally nickel (Ni), in particular in amounts of up to 0.1% by weight, preferably in amounts of up to 0.08% by weight, preferably in amounts of up to 0.06% by weight,
7. (vii) optionally silicon (Si), in particular in amounts of up to 0.1 wt.%, preferably in amounts of up to 0.05 wt.%, preferably in amounts of up to 0.01 wt.%,
8. (viii) optionally magnesium (Mg), in particular in amounts of up to 5 wt.%, preferably in amounts of up to 2.5 wt.%, preferably in amounts of up to 0.8 wt.%.

According to one embodiment of the present invention, the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath can have a temperature in the range from 375 °C to 750 °C, in particular a temperature in the range from 380 °C to 700 °C, preferably a temperature in the range from 390 °C to 680 °C, even more preferably in the range from 395 °C to 675 °C.

Typically, the system used according to the invention is designed such that the hot-dip galvanizing device (G) is designed and/or operable and/or is designed and/or operated in such a way, in particular is controllable and/or is controlled in such a way, in particular by means of a control device, that the iron or steel component is immersed in the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or in the galvanizing bath, in particular immersed therein and moved, in particular for a period of time which is sufficient to ensure effective hot-dip galvanizing (hot-dip galvanizing), in particular for a period of time in the range from 0.0001 to 60 minutes, preferably in the range from 0.001 to 45 minutes, preferably in the range from 0.01 to 30 minutes, even more preferably in the range from 0.1 to 15 minutes.

According to a typical embodiment of the present invention, it can be provided that the hot-dip galvanizing device (G) has at least one device for contacting and/or flushing or passing the aluminum-containing, in particular aluminum-alloyed zinc melt ("Zn/Al melt") and/or the galvanizing bath with at least one inert gas, in particular nitrogen.

As already described above in connection with the method used according to the invention, the system used according to the invention can in principle be designed to be operable continuously or discontinuously or can in principle be operated continuously or discontinuously.

In particular, the system used according to the invention can be designed such that the iron or steel component can be hot-dip galvanized as a single product or as a plurality of individual products or that the iron or steel component can be hot-dip galvanized as a long product, in particular a wire, pipe, sheet, coil material or the like.

Furthermore, it can be provided according to the invention that the system used according to the invention, downstream in the process direction or downstream of the hot-dip galvanizing device (F), also has at least one cooling device (H) for cooling the iron or steel component hot-dip galvanized in the hot-dip galvanizing device (F). In particular, the cooling device (H) can be designed and/or operated in the presence of air. Furthermore, the system used according to the invention, downstream in the process direction or downstream of the optional cooling device (H), also has at least one post-processing and/or post-treatment device (I) for post-processing and/or post-treatment of the hot-dip galvanized and cooled iron or steel component.

For further details on the system used according to the invention, in order to avoid unnecessary repetition, reference can be made to the above statements on the method used according to the invention, which apply accordingly with regard to the system used according to the invention.

Within the scope of the use according to the invention, hot-dip galvanized (hot-dip galvanized) iron or steel components can be produced which are obtainable by a process as described above and in a plant used according to the invention, as described above.

As already described at the outset and in particular also documented by the exemplary embodiments according to the invention, the products obtainable within the scope of the use according to the invention are associated with particular advantages, in particular a reduced transition or heavy metal content as well as improved mechanical properties and corrosion protection properties.

As regards the hot-dip galvanized iron or steel component obtainable within the scope of the use according to the invention, this is provided on its surface with a hot-dip galvanizing layer of 0.5 to 300 µm thickness, in particular 1 to 200 µm thickness, preferably 1.5 to 100 µm thickness, preferably 2 to 30 µm thickness.

As regards the hot-dip galvanized iron or steel component obtainable within the scope of the use according to the invention, this hot-dip galvanized iron or steel component is provided with a hot-dip galvanizing layer on its surface, wherein the hot-dip galvanizing layer is completely free of lead (Pb) and/or nickel (Ni) originating from the flux treatment.

According to the invention, it is particularly preferred if the hot-dip galvanized iron or steel component obtainable within the scope of the use according to the invention is provided with a hot-dip galvanizing layer on its surface, wherein the hot-dip galvanizing layer is completely free of heavy metals originating from the flux treatment from the group of lead (Pb), nickel (Ni), cobalt (Co), manganese (Mn), tin (Sn), bismuth (Bi) and antimony (Sb).

For further details on this aspect, in order to avoid unnecessary repetition, reference can be made to the above comments on the other aspects, which apply accordingly.

Further features, advantages and possible applications of the present invention emerge from the following description of embodiments with reference to drawings and the drawings themselves. All described and/or illustrated features, individually or in any combination, form the subject matter of the present invention, regardless of their summary in the claims and their relationships.

Fig. 1

einen schematischen Verfahrensablauf der einzelnen Stufen bzw. Verfahrensschritte des erfindungsgemäß zur Anwendung kommenden Verfahrens nach einer besonderen Ausführungsform der vorliegenden Erfindung,

Fig. 2

eine schematische Darstellung einer erfindungsgemäß verwendeten Anlage gemäß einer besonderen Ausführungsform der vorliegenden Erfindung.

It shows:

Fig. 1

a schematic process flow of the individual stages or process steps of the process used according to the invention according to a particular embodiment of the present invention,

Fig. 2

a schematic representation of a system used according to the invention according to a particular embodiment of the present invention.

In the Fig. 1 The process flow diagram shown schematically shows the successive process stages or process steps a) to i), whereby the process steps b), d), f), h) and i), in particular the process steps h) and i), are optional.

According to the Fig. 1 According to the diagram shown, the process sequence is as follows, wherein the process used according to the invention comprises the following steps successively in this order: degreasing (step a)), rinsing (step b), optional), pickling (step c)), rinsing (step d), optional), flux bath treatment (step e)), drying (step f), optional), hot-dip galvanizing (step g)), cooling (step h), optional) and post-processing or post-treatment (step i), optional).

For further details on the process sequence used according to the invention, reference can be made to the above general statements on the process used according to the invention.

In Fig. 2 The system used according to the invention with the individual devices (A) to (I) is shown schematically, wherein the devices (B), (D), (F), (H) and (I), in particular the devices (H) and (I), are optional.

According to the Fig. 2 The diagram of the plant used according to the invention shown in the drawing comprises the following devices in the following sequence: degreasing device (A), optionally rinsing device (B), pickling device (C), optionally rinsing device (D), flux treatment device (E), optionally drying device (F), hot-dip galvanizing device (G), if necessary, cooling device (H) and, if necessary, post-processing or post-treatment device (I).

For further details on the system used according to the invention, reference can be made to the above general statements on the system.

Further embodiments, modifications and variations of the present invention are readily apparent and feasible to the person skilled in the art upon reading the description, without departing from the scope of the present invention.

The present invention is illustrated by the following embodiments, which are not intended to limit the present invention in any way, but merely explain the exemplary and non-limiting implementation and design.

EXAMPLES OF IMPLEMENTATION General instructions for implementation (according to the invention)

Various hot-dip galvanizing cycles with sample sheets of type S235 (2 mm thickness, 100 mm x 100 mm width) are carried out according to the process sequence used according to the invention Fig. 1 and with the system used in accordance with the invention Fig. 2 The flux composition and the zinc bath alloys are varied according to the following specifications.

• (a) alkalische Entfettungsbehandlung in einem Entfettungsbad (15 Minuten, 70 °C, Zusammensetzung des Entfettungsbades gemäß Beispiel 1 von EP 1 352 100 B1 ),
• (b) zweifaches Spülen in zwei aufeinander folgenden Spülbädern mit Wasser,
• (c) saure Beizbehandlung (40 Minuten, 30 °C, Zusammensetzung des Beizbades gemäß Beispiel 1 von EP 1 352 100 B1 ),
• (d) zweifaches Spülen in zwei aufeinander folgenden Spülbädern mit Wasser,
• (e) Flussmittelbehandlung in Flussmittelbad gemäß nachfolgender Spezifikationen (3 Minuten, 60 °C, Tauchbehandlung),
• (f) Trocknungsbehandlung (260 °C heißer Luftstrom, 30 Sekunden),
• (g) Feuerverzinkung (Schmelztauchverzinkung) mit einer aluminiumhaltigen bzw. aluminiumlegierten Zinkschmelze ("Zn/Al-Schmelze") in einem Verzinkungsbad gemäß nachfolgender Spezifikationen (50 Sekunden Tauchbehandlung des vorgewärmten und gefluxten Blechs im Verzinkungsbad, 450 °C),
• (i) Abkühlung des aus dem Verzinkungsbad entnommenen und feuerverzinkten Blechs an der Luft.

The hot-dip galvanizing process carried out in each case comprises the following process steps in the order listed below (the system used according to the invention is designed accordingly):

• (a) alkaline degreasing treatment in a degreasing bath (15 minutes, 70 °C, composition of the degreasing bath according to Example 1 of EP 1 352 100 B1 ),
• (b) double rinsing in two consecutive rinsing baths with water,
• (c) acid pickling treatment (40 minutes, 30 °C, composition of the pickling bath according to Example 1 of EP 1 352 100 B1 ),
• (d) double rinsing in two consecutive rinsing baths with water,
• (e) flux treatment in flux bath according to the following specifications (3 minutes, 60 °C, immersion treatment),
• (f) drying treatment (260 °C hot air stream, 30 seconds),
• (g) Hot-dip galvanizing (hot-dip galvanizing) with a zinc melt containing aluminium or aluminium alloy ("Zn/Al melt") in a galvanizing bath according to the following specifications (50 seconds immersion treatment of the preheated and fluxed sheet in the galvanizing bath, 450 °C),
• (i) Cooling in air of the hot-dip galvanized sheet removed from the galvanizing bath.

Example series 1 (according to the invention)

Various sample sheets are subjected to hot-dip galvanizing as described above, including the corresponding pretreatment steps as described above. The specification of the flux composition and flux bath used is as follows:

Flux composition:

78.995% by weight ZnCl ₂ 13% by weight NH ₄ Cl, 6% by weight NaCl, 2% by weight KCl, 0.005% by weight (50 ppm) AlCl ₃

flux bath:

• Flux quantity/concentration (total salt content): 550 g/l
• Ammonia solution (5%): 10 ml per liter of flux bath to adjust (raise) the pH value
• pH value: 3.5 (without ammonia solution: 3.2)
• Wetting agent (non-ionic surfactant): 0.3%

Variation of the alcohol content in the flux bath

1. a) 0% propanol (100% water)
2. b) 5% propanol (40 g propanol, rest made up to 1000 ml with water)
3. c) 20 % propanol (160 g propanol, rest made up to 1000 ml with water)
4. d) 71.8 % propanol (574.4 g propanol, rest made up to 1000 ml with water)
5. e) 100% propanol

galvanizing bath

100 ppm aluminum, 0.05 wt.% bismuth, 0.3 wt.% tin, 0.04 wt.% nickel, balance zinc (i.e. ad 100 wt.%)

Results

ad a) The sheet metal is completely coated with salts by immersion in the flux solution. After the drying step, the surface of the component is still completely wet. A largely homogeneous zinc layer is formed, but with minimal defects.

ad b) The sheet metal is completely coated with salts by immersing it in the flux solution. After the drying step, the surface of the component is already slightly dry. To check this, the sheets are weighed after pickling and drying. Compared to variant a), it can be seen that the flux film weighs 2.5% less, which is due to a lower residual moisture content as a result of faster drying. After galvanizing, a homogeneous zinc layer is formed without any defects.

ad c) The sheet metal is completely coated with salts by immersing it in the flux solution. After the drying step, the surface of the component is largely dry. Comparing the weight of the flux film with variant a) shows an 11.5% weight reduction. After galvanizing, a homogeneous zinc layer is formed without any defects.

ad d) The sheet metal is completely coated with salts by immersing it in the flux solution. After the drying step, the surface of the component is completely dry. Comparing the weight of the flux film with variant a) shows a 15% reduction. After galvanizing, a homogeneous zinc layer is formed without any defects.

ad e) The flux salts form a sediment which cannot be dissolved. Consequently, when the sheet is immersed in the flux, the steel surface is not efficiently wetted with flux salts. During galvanizing, there is no reaction between the zinc alloy and the steel, i.e. efficient galvanization is not possible.

General findings

Under the same drying conditions (i.e. the same drying times and drying temperatures), the use of alcohol in the flux bath leads to faster drying of the flux film and better galvanizing quality, even at low and even high levels. This means that better drying leads to better galvanizing quality.

Even in corrosion tests (salt spray test or salt spray test according to DIN EN ISO 9227:2012), the hot-dip galvanized sheets pretreated with the flux containing alcohol show significantly longer service lives (up to 40% improvement in service life) compared to hot-dip galvanized sheets pretreated with the otherwise identical flux (but without any alcohol content, i.e. purely aqueous).

Example series 2 to 5 (according to the invention)

Example series 1 is repeated, but with a different composition of the galvanizing bath.

Galvanizing bath for example series 2

500 ppm aluminum, 0.05 wt.% bismuth, 0.3 wt.% tin, 0.04 wt.% nickel, balance zinc (i.e. ad 100 wt.%)

Galvanizing bath for example series 3

1,000 ppm aluminum, 50 ppm silicon, balance zinc (i.e. ad 100% by weight)

Galvanizing bath for example series 4

5.42% by weight aluminum, balance zinc (i.e. ad 100% by weight)

Galvanizing bath for example series 5

Aluminum 4.51% by weight, balance zinc (i.e. ad 100% by weight)

Results

Analogous results to example series 1 are obtained, whereby especially in the case of example series 4 and 5, optically significantly improved, i.e. particularly shiny surfaces result.

Example series 6 to 10 (according to the invention)

Example series 1 to 5 are repeated, but with a different flux composition (use of 0.005 wt.% or 50 ppm AgCl instead of AlCl ₃ ).

Results

Analogous results to the example series 1 to 5 are obtained.

Example series 11 to 15 (according to the invention)

Example series 1 to 5 are repeated, but with a different flux composition (using a combination of 0.0025 wt.% or 25 ppm AgCl and 0.0025 wt.% or 25 ppm AlCl ₃ instead of AlCl ₃ alone).

Results

Analogous results to the example series 1 to 5 are obtained.

Example series 16 to 30 (comparison)

Example series 1 to 15 are repeated, but with different flux composition (complete omission of AlCl ₃ and AgCl).

Results

In the case of alcohol contents a) to d), highly inhomogeneous zinc layers with a significant number of defects and clearly visible defect structures result after galvanizing.

In the case of the alcohol contents of e), galvanizing is also not possible at all, since the flux salts form an insoluble sediment.

General formulations for fluxes (according to the invention)

In the following, general recipe information is given for typical flux compositions and flux baths used according to the invention with optimization depending on the composition of the zinc/aluminum melt. <u>Flux composition</u> ZnCl ₂ 56 to 85% For AI = 4.2 to 6.2%: typically 77 to 82% For AI up to 1,000 ppm: typically 56 to 62% NH ₄ Cl 10 to 44% For AI = 4.2 to 6.2%: typically 10 to 15% For AI up to 1,000 ppm: typically 38 to 44% NaCl > 0 to 6% For AI = 4.2 to 6.2%: typically 5 to 7% For AI up to 1,000 ppm: typically > 0 to 1% KCI > 0 to 2% For AI = 4.2 to 6.2%: typically 1 to 3% For AI up to 1,000 ppm: typically > 0 to 0.5% AgCl/AlCl ₃ 0.5 to 500 ppm

All above percentages (wt.%) are based on the solid salt content (dry weight).

flux bath

Total salt content (flux composition) 200 to 700 g/l, typically 450 to 550 g/l
pH in the range of 25 to 5 For AI =4.2 to 6.2%: typically 2.5 to 3.5 For AI up to 1,000 ppm: typically 4 to 5%
sufficient amount of inorganic acid and ammonia solution to adjust the required pH value (fine adjustment with ammonia solution)
Flux temperature in the range of 15 to 80 °C For AI = 4.2 to 6.2%: typically 50 to 70°C For AI up to 1,000 ppm: typically 35 to 60°C
wetting agent content 0.2 to 5%
Solution with a proportion of propanol and/or ethanol of 0.2 to 72% For AI=4.2 to 6.2%: typically 5 to 20% For AI up to 1,000 ppm: typically 5 to 20%

Claims (14)

1. Use of a system for hot-dip galvanizing iron or steel components,
   wherein the system comprises the following treatment devices in the sequence listed below:

   (A) at least one degreasing device for the degreasing treatment of iron or steel components;
   downstream in the process direction or downstream to (A)

   (B) optionally, at least one rinsing device for rinsing the iron or steel components degreased in the degreasing device (A);
   downstream in the process direction or downstream to (B)

   (C) at least one pickling device for the pickling treatment of the iron or steel components degreased in the degreasing device (A) and optionally rinsed in the rinsing device (B);
   downstream in the process direction or downstream to (C)

   (D) optionally, at least one rinsing device for rinsing the iron or steel components pickled in the pickling device (C);
   downstream in the process direction or downstream to (D)

   (E) at least one flux treatment device for the flux treatment of the iron or steel components pickled in the pickling device (C) and optionally rinsed in the rinsing device (D), wherein the flux treatment device contains at least one flux bath with a flux composition,

   wherein the flux bath comprises a liquid phase containing an alcohol/water-mixture, wherein the liquid phase of the flux bath contains the flux composition, wherein the alcohol of the alcohol/water-mixture of the flux bath is a water-miscible and/or a water-soluble alcohol and is selected from the group of linear or branched, saturated or unsaturated, aliphatic, cycloaliphatic or aromatic, primary, secondary or tertiary monohydric C₁-C₄ alcohols and mixtures thereof,
   and

   wherein the flux composition contains as ingredients

   (i) zinc chloride (ZnCl₂) in amounts in the range of from 50 to 95 % by weight,

   (ii) ammonium chloride (NH₄Cl) in amounts in the range of from 5 to 45 % by weight,

   (iii) at least one alkali metal and/or alkaline earth metal salt in amounts in the range of from 0.1 to 25 % by weight and

   (iv) at least one aluminum salt and/or at least one silver salt in amounts in the range of from 5 • 10^-5 to 2 % by weight,

   wherein all above amounts are based on the composition and are to be selected such that a total of 100 % by weight results,
   and

   wherein the flux composition is completely free of lead chloride (PbCl₂) and nickel chloride (NiCl₂);

   downstream in the process direction or downstream to (E)

   (F) at least one drying device (F) for drying the iron or steel components subjected to the flux treatment in the flux treatment device (E),

   wherein the drying device (F) is controlled by means of a control device such that the drying treatment is carried out such that the surface of the iron or steel component has a temperature in the range of from 100 to 300 °C during drying,

   wherein the drying device (F) has at least one inlet for introducing and/or letting in air, and

   wherein the drying device (F) comprises at least one drying means;

   downstream in the process direction or downstream to (F)

   (G) at least one hot-dip galvanizing device for hot-dip galvanizing the iron or steel components subjected to the flux treatment in the flux treatment device (E) and optionally dried in the drying device (F),
   wherein the hot-dip galvanizing device comprises at least one galvanizing bath containing an aluminum-containing zinc melt designed for dipping iron or steel components.
2. Use according to claim 1,

   wherein the flux bath is acidic; and/or

   wherein the flux bath is adjusted to a defined and/or predetermined, especially acidic pH value, especially in the pH value range of from 0 to 6.9, preferentially in the pH value range of from 0.5 to 6.5, preferably in the pH value range of from 1 to 5.5, more preferably in the pH value range of from 1.5 to 5, even more preferably in the pH value range of from 2 to 4.5, further preferably in the pH value range of from 2 to 4; and/or

   wherein the flux bath is adjusted to a defined and/or predetermined, especially acidic pH value, wherein the pH value is adjusted by means of a preferentially inorganic acid in combination with a preferentially inorganic basic compound, especially ammonia (NH₃).
3. Use according to claim 1 or 2,

   wherein the flux bath contains the alcohol/water-mixture in a weight-related alcohol/water quantity ratio in the range of from 0.5 : 99.5 to 99 : 1, especially in the range of from 2 : 98 to 95 : 5, preferentially in the range of from 5 : 95 to 90 : 10, preferably in the range of from 5 : 95 to 50 : 50, more preferably in the range of from 5 : 95 to 45 : 55, even more preferably in the range of from 5 : 95 to 50 : 50, further more preferably in the range of from 10 : 90 to 30 : 70, based on the alcohol/water-mixture; and/or

   wherein the flux bath contains the alcohol, based on the alcohol/water-mixture, in an amount of at least 0.5 % by weight, especially in an amount of at least 1 % by weight, preferentially in an amount of at least 2 % by weight, more preferably in an amount of at least 3 % by weight, even more preferably in an amount of at least 4 % by weight; and/or wherein the flux bath contains the alcohol, based on the alcohol/water-mixture, in an amount of up to 90 % by weight, especially in an amount of up to 70 % by weight, preferentially in an amount of up to 50 % by weight, more preferably in an amount of up to 30 % by weight, even more preferably in an amount of up to 25 % by weight; and/or wherein the alcohol of the alcohol/water-mixture of the flux bath is selected from the group consisting of methanol, ethanol, propan-1-ol, propan-2-ol, butan-1-ol, butan-2-ol and mixtures thereof.
4. Use according to any of the preceding claims,

   wherein the flux bath also contains at least one wetting agent and/or surfactant, especially at least one ionic or non-ionic wetting agent and/or surfactant, preferably at least one non-ionic wetting agent and/or surfactant;

   especially wherein the flux bath contains the at least one wetting agent and/or surfactant in amounts of 0.0001 to 15 % by weight, preferentially in amounts of 0.001 to 10 % by weight, preferably in amounts of 0.01 to 8 % by weight, more preferably in amounts of 0.01 to 6 % by weight, even more preferably in amounts of 0.05 to 3 % by weight, further preferably in amounts of 0.1 to 2 % by weight, based on the flux bath; and/or

   especially wherein the flux bath contains the at least one wetting agent and/or surfactant in amounts of 0.0001 to 10 % by volume, preferentially in amounts of 0.001 to 8 % by volume, preferably in amounts of 0.01 to 5 % by volume, more preferably in amounts of 0.01 to 5 % by volume, even more preferably in amounts of 0.05 to 3 % by volume, further preferably in amounts of 0.1 to 2 % by volume, based on the flux bath.
5. Use according to any of the preceding claims,

   wherein the flux bath contains the flux composition in an amount of at least 150 g/l, especially in an amount of at least 200 g/l, preferentially in an amount of at least 250 g/l, preferably in an amount of at least 300 g/l, more preferably in an amount of at least 400 g/l, even more preferably in an amount of at least 450 g/l, further preferably in an amount of at least 500 g/l, especially calculated as the total salt content of the flux composition; and/or

   wherein the flux bath contains the flux composition in an amount of 150 g/l to 750 g/l, especially in an amount of 200 g/l to 700 g/l, preferentially in an amount of 250 g/l to 650 g/l, preferably in an amount of 300 g/l to 625 g/l, more preferably in an amount of 400 g/l to 600 g/l, even more preferably in an amount of 450 g/l to 580 g/l, further preferably in an amount of 500 g/l to 575 g/l, especially calculated as the total salt content of the flux composition.
6. Use according to any of the preceding claims,

   where the flux composition contains as ingredients

   (i) zinc chloride (ZnCl₂) in amounts in the range of from 55 to 90 % by weight, preferably in the range of from 60 to 85 % by weight, more preferably in the range of from 65 to 82.5 % by weight, even more preferably in the range of from 70 to 82 % by weight,

   (ii) ammonium chloride (NH₄Cl) in amounts in the range of from 7.5 to 40 % by weight, preferably in the range of from 10 to 35 % by weight, more preferably in the range of from 11 to 25 % by weight, even more preferably in the range of from 12 to 20 % by weight,

   (iii) at least one alkali metal and/or alkaline earth metal salt in amounts in the range of from 0.5 to 20 % by weight, preferably in the range of from 1 to 15 % by weight, more preferably in the range of from 2 to 12.5 % by weight, even more preferably in the range of from 4 to 10 % by weight, and

   (iv) at least one aluminum salt and/or at least one silver salt in amounts in the range of from 5 • 10^-5 to 5 • 10^-3 % by weight

   wherein all the above amounts are based on the composition and are to be selected such that a total of 100 % by weight results, and

   wherein the flux composition is completely free of lead chloride (PbCl₂) and nickel chloride (NiCl₂).
7. Use according to any of the preceding claims,

   wherein the flux composition contains an alkali metal and/or alkaline earth metal chloride as the alkali metal and/or alkaline earth metal salt of component (iii); and/or

   wherein the flux composition contains as alkali metal and/or alkaline earth metal salt of component (iii) at least one alkali metal and/or alkaline earth metal salt of an alkali metal and/or alkaline earth metal from the group of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) and combinations thereof; and/or

   wherein the flux composition comprises, as alkali metal and/or alkaline earth metal salt of component (iii), at least two different alkali metal and/or alkaline earth metal salts, especially at least two alkali metal and/or alkaline earth metal salts of an alkali metal and/or alkaline earth metal from the group consisting of lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) and combinations thereof; and/or

   wherein the flux composition contains as alkali metal and/or alkaline earth metal salt of component (iii) at least two alkali metal salts different from each other, especially two different alkali metal chlorides, preferentially sodium chloride and potassium chloride, especially with a sodium/potassium weight ratio in the range of from 50 : 1 to 1 : 50, especially in the range of from 25 : 1 to 1 : 25, preferentially in the range of from 10 : 1 to 1 : 10.
8. Use according to any of the preceding claims,

   wherein the flux composition is also completely free of cobalt chloride (C_oCl₂), manganese chloride (MnCl₂), tin chloride (SnCl₂), bismuth chloride (BiCl₃) and antimony chloride (SbCl₃); and/or

   wherein the flux composition is completely free of lead chloride (PbCl₂), nickel chloride (NiCl₂), cobalt chloride (CoCl₂), manganese chloride (MnCl₂), tin chloride (SnCl₂), bismuth chloride (BiCl₃) and antimony chloride (SbCl₃) and/or wherein the flux composition is completely free of chlorides from the group of lead chloride (PbCl₂), nickel chloride (NiCl₂), cobalt chloride (C_oCl₂), manganese chloride (MnCl₂), tin chloride (SnCl₂), bismuth chloride (BiCl₃) and antimony chloride (SbCl₃); and/or

   wherein the flux composition is completely free of salts and compounds of metals selected from the group of lead (Pb), nickel (Ni), cobalt (Co), manganese (Mn), tin (Sn), bismuth (Bi) and antimony (Sb); and/or

   wherein the flux composition, apart from zinc chloride (ZnCl₂) and aluminum and/or silver salt, especially silver chloride (AgCI) and/or aluminum chloride (AlCl₃), is completely free of salts and compounds of transition and heavy metals.
9. Use according to any of the preceding claims,

   wherein the flux treatment device (E) comprises a device for bringing the iron or steel component into contact with the flux bath and/or the flux composition, especially a device for dipping or for spray application, preferentially a device for dipping, especially wherein the device for bringing the iron or steel component into contact with the flux bath and/or the flux composition can be controlled and/or is controlled, especially by means of a control device, such that the iron or steel component is brought into contact with the flux bath and/or the flux composition, especially is immersed in the flux bath, for a duration of 0.001 to 30 minutes, especially 0.01 to 20 minutes, preferentially 0.1 to 15 minutes, preferably 0.5 to 10 minutes, more preferably 1 to 5 minutes, and/or especially wherein the device for bringing the iron or steel component into contact with the flux bath and/or the flux composition can be controlled and/or is controlled, especially by means of a control device, such that the iron or steel component is brought into contact with the flux bath and/or the flux composition, especially is immersed in the flux bath, for a duration of up to 30 minutes, especially up to 20 minutes, preferentially up to 15 minutes, preferably up to 10 minutes, more preferably up to 5 minutes; and/or

   wherein the drying device (F) comprises at least one oven.
10. Use according to any of the preceding claims,
    wherein the aluminum-containing, especially aluminum-alloyed zinc melt ("Zn/AI-melt") and/or the galvanizing bath contains an amount of aluminum in the range of from 0.0001 to 25 % by weight, especially in the range of from 0.001 to 20 % by weight, preferentially in the range of from 0.005 to 17.5 % by weight, preferably in the range of from 0.01 to 15 % by weight, more preferably in the range of from 0.02 to 12.5 % by weight, even more preferably in the range of from 0.05 to 10 % by weight, further preferably in the range of from 0.1 to 8 % by weight, based on the aluminum-containing, especially aluminum-alloyed zinc melt ("Zn/AI-melt") and/or the galvanizing bath, especially wherein the aluminum-containing, especially aluminum-alloyed zinc melt ("Zn/AI-melt") and/or the galvanizing bath, based on the aluminum-containing, especially aluminum-alloyed zinc melt ("Zn/AI-melt") and/or the galvanizing bath, contains an amount of zinc of at least 75 % by weight, especially at least 80 % by weight, preferentially at least 85 % by weight, preferably at least 90 % by weight, and optionally at least one further metal, especially in amounts of up to 5 % by weight and/or especially selected from the group of bismuth (Bi), lead (Pb), tin (Sn), nickel (Ni), silicon (Si), magnesium (Mg) and combinations thereof, wherein all the above-mentioned amounts are to be selected such that a total of 100 % by weight results.
11. Use according to any of the preceding claims,
    wherein the aluminum-containing, especially aluminum-alloyed zinc melt ("Zn/AI-melt") and/or the galvanizing bath has the following composition, wherein all the amounts stated below are related to the aluminum-containing, especially aluminum-alloyed zinc melt ("Zn/AI-melt") and/or the galvanizing bath and are to be selected such that a total of 100 % by weight results:

    (i) zinc (Zn), especially in amounts in the range of from 75 to 99.9999 % by weight, especially in the range of from 80 to 99.999 % by weight, preferentially in the range of from 82.5 to 99.995 % by weight, preferably in the range of from 85 to 99.99 % by weight, more preferably in the range of from 87.5 to 99.98 % by weight, even more preferably in the range of from 90 to 99.95 % by weight, further preferably in the range of from 92 to 99.9 % by weight,

    (ii) aluminum (Al), especially in amounts in the range of from 0.0001 to 25 % by weight, especially in the range of from 0.001 to 20 % by weight, preferentially in the range of from 0.005 to 17.5 % by weight, preferably in the range of from 0.01 to 15 % by weight, more preferably in the range of from 0.02 to 12.5 % by weight, even more preferably in the range of from 0.05 to 10% by weight, further preferably in the range of from 0.1 to 8 % by weight,

    (iii) optionally bismuth (Bi), especially in amounts of up to 0.5 % by weight, preferentially in amounts of up to 0.3 % by weight, preferably in amounts of up to 0.1 % by weight,

    (iv) optionally lead (Pb), especially in amounts of up to 0.5 % by weight, preferentially in amounts of up to 0.2 % by weight, preferably in amounts of up to 0.1 % by weight,

    (v) optionally tin (Sn), especially in amounts of up to 0.9 % by weight, preferentially in amounts of up to 0.6 % by weight, preferably in amounts of up to 0.3 % by weight,

    (vi) optionally nickel (Ni), especially in amounts of up to 0.1 % by weight, preferentially in amounts of up to 0.08 % by weight, preferably in amounts of up to 0.06 % by weight,

    (vii) optionally silicon (Si), especially in amounts of up to 0.1 % by weight, preferentially in amounts of up to 0.05 % by weight, preferably in amounts of up to 0.01 % by weight

    (viii) optionally magnesium (Mg), especially in amounts of up to 5 % by weight, preferentially in amounts of up to 2.5 % by weight, preferably in amounts of up to 0.8 % by weight.
12. Use according to any of the preceding claims,

    wherein the aluminum-containing, especially aluminum-alloyed zinc melt ("Zn/AI-melt") and/or the galvanizing bath has a temperature in the range of from 375 °C to 750 °C, especially a temperature in the range of from 380 °C to 700 °C, preferentially a temperature in the range of from 390 °C to 680 °C, more preferably in the range of from 395 °C to 675 °C; and/or

    wherein the hot-dip galvanizing device (G) is designed and/or can be operated and/or is designed and/or operated, especially can be controlled and/or is controlled, especially by means of a control device, such that the iron or steel component is immersed in the aluminum-containing, especially aluminum-alloyed zinc melt ("Zn/AI-melt") and/or in the galvanizing bath, especially immersed and moved therein, especially for a period of time which is sufficient to ensure effective hot-dip galvanizing, especially for a period of time in the range of from 0.0001 to 60 minutes, preferentially in the range of from 0.001 to 45 minutes, preferably in the range of from 0.01 to 30 minutes, more preferably in the range of from 0.1 to 15 minutes; and/or

    wherein the hot-dip galvanizing device (G) has at least one device for contacting and/or flushing or passing through the aluminum-containing, especially aluminum-alloyed zinc melt ("Zn/AI-melt") and/or the galvanizing bath with at least one inert gas, especially nitrogen.
13. Use according to any of the preceding claims,

    wherein the system is designed to be operated continuously or discontinuously and/or is operated continuously or discontinuously; and/or

    wherein the system is designed such that the iron or steel component can be hot-dip galvanized as a single product or as a plurality of individual products or that the iron or steel component can be hot-dip galvanized as a long product, especially a wire, tube, sheet, coil material or the like.
14. Use according to any of the preceding claims,
    wherein the system, connected downstream or downstream of the hot-dip galvanizing device (F) in the process direction, further comprises at least one cooling device (H) for cooling the iron or steel component hot-dip galvanized in the hot-dip galvanizing device (F), especially wherein the cooling device (H) is designed and/or operated so as to be operable in the presence of air and/or especially wherein the system further comprises at least one post-processing and/or post-treatment device (l) for post-processing and/or post-treating the hot-dip galvanized and cooled iron or steel component hot-dip galvanized in the hot-dip galvanizing device (F), downstream or downstream of the cooling device (H) in the process direction.

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