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EP0155547B1 - Process for the zinc-calcium phosphatizing of metal surfaces at a low treating temperature - Google Patents

Process for the zinc-calcium phosphatizing of metal surfaces at a low treating temperature Download PDF

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Publication number
EP0155547B1
EP0155547B1 EP85102057A EP85102057A EP0155547B1 EP 0155547 B1 EP0155547 B1 EP 0155547B1 EP 85102057 A EP85102057 A EP 85102057A EP 85102057 A EP85102057 A EP 85102057A EP 0155547 B1 EP0155547 B1 EP 0155547B1
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EP
European Patent Office
Prior art keywords
phosphating
solutions
metal surfaces
zinc
phosphate
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
EP85102057A
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German (de)
French (fr)
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EP0155547A1 (en
Inventor
Reinhard Opitz
Manfred Breuer
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Gerhard Collardin GmbH
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Gerhard Collardin GmbH
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Priority to AT85102057T priority Critical patent/ATE39135T1/en
Publication of EP0155547A1 publication Critical patent/EP0155547A1/en
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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
    • C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates
    • C23C22/367—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates containing alkaline earth metal cations
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/07—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing phosphates
    • C23C22/08—Orthophosphates
    • C23C22/22—Orthophosphates containing alkaline earth metal cations
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/05—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions
    • C23C22/06—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6
    • C23C22/34—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides
    • C23C22/36—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using aqueous solutions using aqueous acidic solutions with pH less than 6 containing fluorides or complex fluorides containing also phosphates

Definitions

  • the invention relates to a method for phosphating metal surfaces, in particular surfaces made of iron, steel, zinc and / or aluminum, for pretreating the metal surfaces for electrocoating, in particular for cathodic electrocoating, using a zinc, calcium, phosphate and accelerator, and, if appropriate phosphating solution containing further additives.
  • non-layer-forming phosphating i.e. the use of alkali and / or ammonium orthophosphate solutions for the production of iron phosphate layers, in which the iron ion comes from the metallic surface to be coated
  • layer-forming phosphating in which on metal surfaces using zinc or zinc / calcium / calcium phosphate Solutions of zinc phosphate layers or zinc calcium phosphate layers are formed.
  • Such phosphate layers not only improve the corrosion protection of the metal surfaces, but also increase the adhesion for paints to be applied to the surface. In certain cases, they can also help to improve the properties of metal sheets during cold forming and when using deep-drawing processes.
  • Zinc-calcium-phosphate solutions are increasingly being used especially for the phosphating of metal surfaces that are later to be coated with electrocoating materials.
  • composition of the bathroom solutions on the one hand and basic knowledge about the structure of phosphating layers on the other (A. Neuhaus and M. Gebhardt, Maschinentechnik und Korrosion, 567 (1966)) have conveyed the teaching that the construction of uniform and closed phosphating layers is not only of depends on the composition of the bath solutions, but also on the pretreatment of the raw sheets, the activation before the phosphating step, the choice of a suitable accelerator and other process parameters.
  • DE-A-1 521 818 discloses, inter alia, aqueous phosphating solutions which contain 0.01 to 1.5% calcium, 0.3 to 6% phosphate, 0.02 to 0.5% zinc as essential components. , 0.05 to 3% nitrate, 0.015 to 0.4% nickel and 0.001 to 0.02% nitrite ions, have an overall acidity in the range of 5 to 50 points and allow the phosphating of galvanized ferrous metal surfaces.
  • Solution A 0.11% Ca, 0.078% Zn, 0.995% P0 4 , 0.048% Ni, 0.0396% N0 3 , 0.002% N0 2 , total acid points: 13.6;
  • Solution B 0.098% Ca, 0.043% Zn, 1.04% P0 4 , 0.07% Ni, 0.486% N0 3 , 0.002% NO 2 , total acid points: 14.8.
  • the solutions used in the examples contain high levels of zinc and calcium ions with a low phosphate ion content; the weight ratio of the sum of zinc and calcium ions to phosphate ions is in the range from 1: 3.5 to 1: 7.4.
  • the temperature of the aqueous phosphating solutions can vary within wide limits, for example from about room temperature to about 116 ° C. In general, the best results are obtained when the aqueous phosphating solutions are used at a temperature of at least about 38 ° C, generally within the range of about 49 to about 93 ° C.
  • DE-A-3 118 375 relates to a process for phosphating metals and its use for pretreatment for electrocoating.
  • the metal surfaces in particular those made of iron, steel and zinc, are brought into contact with acidic, aqueous, oxidizing agent-containing zinc phosphate solutions which contain 0.4 to 1.5 g / l Zn, 0 to 1.3 g / l Ni and 10 to 26 g / l contain P 2 0 5 , the weight ratio of Zn to P 2 0 5 to a value of (0.012 to 0.12): 1 and of Ni to Zn to a value of (0 to 1.5): 1 is set.
  • the temperature of the solutions is preferably in the range from 30 to 65 ° C.
  • solutions which are 2 to 25 g / l N0 3 , 1 to 6 g / l CI0 3 , 0.1 to 2 g / l organic nitro compound, 0.05 to 0.5 g / l N0 2 and / or contain 0.02 to 0.1 g / l peroxide (calculated as H 2 0 2 ).
  • the solutions can also contain other cations, for example calcium, copper, manganese, cobalt, magnesium; however, their content is usually not more than 0.5 g / l.
  • activating agents e.g. B. on titanium phosphate basis, in the pre-rinse bath or in the last cleaning stage.
  • EP-A-45 110 describes a process for the production of phosphate coatings on iron or steel surfaces with an aqueous acidic zinc phosphate solution and its use for the preparation of metal surfaces for cold working.
  • the metal surfaces are treated with solutions containing at least 0.3 percent by weight Zn, at least 0.3 percent by weight P0 4 and at least 0.75 percent by weight N0 3 or an equivalent iron (11) non-oxidizing accelerator, the weight ratio ZB: P0 4th is greater than 0.8, the ratio of total acid to free acid is at least 5 and in which is adjusted by suitable measurement of C10 3 or an equivalent iron (11) to iron (111) oxidizing accelerator, an iron (11) content of 0.04 to 1 percent by weight.
  • Such solutions can additionally contain calcium in amounts of 0.1 to 0.88 percent by weight; the weight ratio Zn: Ca should be 1.5 to 4.
  • the temperature of the solutions is in the range from 35 to 98 ° C.
  • the previously cleaned metal surfaces can be subjected to an activation treatment, for example by hot water rinsing or with a titanium orthophosphate dispersion.
  • DE-A-2 540 685 also describes a process for the production of phosphate coatings on metal surfaces, in particular iron and steel, which has proven itself as a preparation for non-cutting cold forming.
  • the metal surfaces are treated with such solutions at temperatures between 35 and 98 ° C for about 5 to 15 minutes in immersion or flooding. Before the phosphating treatment, the metal surfaces can be activated by pre-rinsing with hot water or with titanium orthophosphate dispersions.
  • aqueous, acidic phosphating solutions described here contain zinc, phosphate and nitrate and autocatalytically form nitrite.
  • an N0 2 content of at least 0.03 g / l is to be maintained in the phosphating bath, but an increase to more than 0.2 g / l is to be prevented by adding a nitrite-destroying substance - for example urea, amidosulfonic acid, chlorate, peroxide .
  • These solutions can also contain at least 0.4 g / l of Ca, but not more than 3 parts by weight of Ca per 1 part by weight of Zn.
  • the application temperatures here are in the range from 60 to 90.degree.
  • Aqueous solutions for phosphating processes which contain zinc, calcium, phosphate and optionally also nickel ions and additionally H 2 0 2 as accelerators are described in BE-A-811 220.
  • the application temperatures of such solutions are also relatively high.
  • the content of zinc and calcium ions is very high.
  • the quality of the heavy metal phosphate layers formed in the phosphating step is highly dependent on the degreasing pretreatment of the metal surfaces and on the activation.
  • the activation step in particular is of great importance insofar as it forms the basis for the adhesion of the later phosphate layers and thus significantly influences the quality of the phosphate coatings which form.
  • the desired formation of thin, fine-grained, crystalline phosphate coatings can only be achieved after sufficient activation by suitable activating agents, e.g. Activation solutions containing phosphate are possible. This results in particular in the difficulty of avoiding speck formation, which adversely affects the quality of the phosphating layer.
  • the method according to the invention is particularly suitable for the phosphating of metal surfaces made of iron, steel and zinc.
  • surfaces made of aluminum with zinc-calcium layers are also to be coated with the method according to the invention.
  • the treated metal surfaces are coated with a layer of dizinc calcium phosphate dihydrate (Scholzit).
  • Scholzit dizinc calcium phosphate dihydrate
  • zinc and calcium ions are incorporated into the phosphating layer in a molar ratio of 2: 1, it is essential for the composition of the bath solutions according to the process according to the invention that they contain zinc and calcium ions in a weight ratio of 1: 0.5 to 1 : 1.5, preferably in a ratio of 1: 1.
  • suitable water-soluble zinc or calcium salts or solutions are added to the solutions, so that the Zn 2+ content is 0.5 to 1.5 g / l phosphating solution and the Ca 2+ content is more than 0. 5 to 1.5 g / l phosphating solution.
  • ZnO, phosphoric acid and Ca (NO 3 ) 2 .4H 2 0 are used as starting compounds.
  • the proportion of P043 ions in the phosphating solutions according to the invention which can be adjusted by means of phosphoric acid is considerably higher: it is in the range from 10 to 50 g / l.
  • the stated amounts of the active ions forming the main constituents of the phosphating solution according to the invention are therefore characterized in that the weight ratio of the sum of calcium and zinc to phosphate is always in the range from 1: greater than 8 to 1:40. This ensures that homogeneous Scholzit layers are formed on all treated metal surfaces; the formation of e.g. B. tertiary zinc phosphate tetrahydrate (Hopeit) or dizine iron phosphate tetrahydrate (phosphophyllite), which together with scholzite would lead to a less homogeneous and poorly adhering protective layer, is not observed.
  • Hopeit tertiary zinc phosphate tetrahydrate
  • phosphophyllite dizine iron phosphate tetrahydrate
  • Another essential process parameter is the fact that the molar ratio of free acid to total acid (acid ratio) has to be set to values from 1:10 to 1:60. This means in particular that a relatively low value for the concentration of free acid is particularly important for the formation of good scholzite layers.
  • the phosphating bath solutions for the process according to the invention are nitrate ions in an amount of 0.5 to 30 g / l, nitrite ions in an amount of 0.01 to 0.6 g / l, chlorate Ions in an amount of 0.2 to 10 g / l, organic nitro compounds in an amount of 0.1 to 2 g / l and / or inorganic peroxides or H 2 0 2 in an amount of 0.01 to 0.5 g / l bath solution added.
  • the phosphating solutions with which metal surfaces are phosphated according to the method according to the invention can also contain further metal ions, e.g. Ni2 + .Your content is in the range of 0.01 to 1.5 g / i bath solution.
  • the treatment of the iron, steel, zinc and / or aluminum surfaces according to the present method can be carried out by spraying, dipping or flooding; however, they are also combined processes, e.g. Spray diving applicable with equally good success.
  • the times during which the phosphating solutions are in contact with the metal surfaces are between 60 and 240 seconds. B. for spraying between 60 to 180 sec and for diving 90 to 240 sec. However, much shorter treatment times are possible.
  • the metal surfaces are treated with the phosphating solutions in the temperature range from 30 to 65 ° C. Temperatures between 48 and 57 ° C are preferably used.
  • One of the main advantages of the method according to the invention is that the formation of the scholzite layers on the metal surfaces takes place completely independently of the type of cleaning which preceded the phosphating step.
  • the method according to the invention there is complete freedom with regard to the choice of degreasing and cleaning agents.
  • the phosphating solutions according to the invention were prepared by processes known per se by combining the desired components, in particular concentrates, salts and solutions containing zinc oxide, phosphoric acid and calcium nitrate tetrahydrate and diluting them with water to the concentrations according to the invention.
  • the phosphate layers produced were finely crystalline and closed.
  • the sheets were then coated with a cathodic electrocoating material and dried for 20 minutes by heating at 185 ° C.
  • the dry film thickness of the lacquer was 18 ⁇ m.
  • the sheets were then provided with a single cut in accordance with DIN 53167 and subjected to the salt spray test in accordance with DIN 50 021 for a period of 480 h.
  • the evaluation according to DIN 53 167 showed an infiltration of ⁇ 0.1 mm.
  • the example illustrates that the process according to the invention produces good phosphate layers.
  • the phosphate layers produced were finely crystalline and closed.
  • the sheets were then coated with a cathodic electrocoating material and dried for 20 minutes by heating at 185 ° C.
  • the dry film thickness of the lacquer was 18 ⁇ m.
  • the sheets were then provided with a single cut in accordance with DIN 53 167 and subjected to the salt spray test in accordance with DIN 50 021 for a period of 480 h.
  • the evaluation according to DIN 53 167 showed an infiltration of ⁇ 0.1 mm.
  • the example illustrates that the process according to the invention produces good phosphate layers.
  • Electrolytically galvanized steel sheets which had been previously cleaned with an alkaline cleaning solution at 50 ° C. for 3 minutes by immersion treatment and rinsed with water, were treated with the aforementioned phosphating solution for 3 minutes at 57 ° C. while immersing. It was then rinsed with water and distilled water and dried by compressed air.
  • the phosphate layers produced were finely crystalline and closed.
  • the sheets were then coated with a cathodic electrocoating material and dried for 20 minutes by heating at 185 ° C.
  • the dry film thickness of the lacquer was 18 ⁇ m.
  • the sheets were then provided with a single cut according to DIN 53 167 and the salt spray test according to DIN 50 021 during one Subjected to a duration of 480 h.
  • the evaluation according to DIN 53167 showed an infiltration of ⁇ 0.1 mm.
  • the example illustrates that the process according to the invention produces good phosphate layers.
  • the phosphate layers produced were finely crystalline and closed.
  • the sheets were then coated with a cathodic electrocoating material and dried for 20 minutes by heating at 185 ° C.
  • the dry film thickness of the lacquer was 18 ⁇ m.
  • the sheets were then provided with a single cut in accordance with DIN 53 167 and subjected to the salt spray test in accordance with DIN 50 021 for a period of 480 h.
  • the evaluation according to DIN 53 167 showed an infiltration of 0.2 mm.
  • the example illustrates that the process according to the invention produces good phosphate layers.
  • solution B was prepared.
  • the sheets were then coated with a cathodic electrocoating material and dried by heating at 185 ° C. for 20 minutes.
  • the dry film thickness of the lacquer was 18 ⁇ m.
  • the sheets were then provided with a single cut according to DIN 53 167 and were happy to do the salt spray test. Subject to DIN 50 021 for a period of 480 h. The evaluation according to DIN 53 167 showed an infiltration of 4 to 6 mm.
  • the comparative example illustrates that, in contrast to the examples according to the invention, significantly reduced corrosion protection is achieved.

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)

Abstract

The invention relates to a process for phosphatizing metal surfaces with an acidic phosphatizing solution containing zinc ions, calcium ions, phosphate ions and accelerators and, optionally, other additives, characterized in that, after degreasing and without activation, the metal surfaces are brought into contact at 30 DEG to 65 DEG C. with solutions which contain Zn2+, Ca2+, PO43- and, as accelerators, nitrate and/or nitrite and/or chlorate ions and/or an organic nitro compound and/or H2O2 or an inorganic peroxide and which have a pH-value of from 2.2 to 3.8, a ratio of free acid to toal acid of from 1:10 to 1:60 and a ratio by weight of (Ca2++Zn2+) to PO43- of from 1:>8 to 1:40, and to the use of this process for pretreating the metal surfaces for painting by electrodeposition, particularly by cathodic electrodeposition.

Description

Die Erfindung betrifft ein Verfahren zur Phosphatierung von Metalloberflächen, insbesondere von Oberflächen aus Eisen, Stahl, Zink und/oder Aluminium, zur Vorbehandlung der Metalloberflächen für die Elektrotauchlackierung, insbesondere für die kathodische Elektrotauchlackierung, mittels einer Zink, Calcium, Phosphat und Beschleuniger, sowie gegebenenfalls weitere Zusätze enthaltende Phosphatierlösung.The invention relates to a method for phosphating metal surfaces, in particular surfaces made of iron, steel, zinc and / or aluminum, for pretreating the metal surfaces for electrocoating, in particular for cathodic electrocoating, using a zinc, calcium, phosphate and accelerator, and, if appropriate phosphating solution containing further additives.

Der Schutz metallischer Oberflächen, insbesondere der Schutz von Eisen- und Stahloberflächen, durch phosphathaltige Überzüge ist seit langer Zeit bekannt. Dabei werden die sogenannte «nicht-schichtbildende Phosphatierung», d.h. die Verwendung von Alkali- und/oder Ammoniumorthophosphatlösungen zur Erzeugung von Eisenphosphatschichten, in denen das Eisenion aus der zu überziehenden metallischen Oberfläche stammt, und die sogenannte «schichtbildende Phosphatierung» unterschieden, bei der auf Metalloberflächen unter Verwendung von Zink- oder Zink-/Calciumphosphat-Lösungen Zinkphosphatschichten bzw. Zink-Calciumphosphat-Schichten gebildet werden.The protection of metallic surfaces, in particular the protection of iron and steel surfaces, by phosphate-containing coatings has been known for a long time. The so-called "non-layer-forming phosphating", i.e. the use of alkali and / or ammonium orthophosphate solutions for the production of iron phosphate layers, in which the iron ion comes from the metallic surface to be coated, and the so-called "layer-forming phosphating", in which on metal surfaces using zinc or zinc / calcium / calcium phosphate Solutions of zinc phosphate layers or zinc calcium phosphate layers are formed.

Derartige Phosphatschichten verbessern nicht nur den Korrosionsschutz der Metalloberflächen, sondern erhöhen auch die Haftung für auf die Oberfläche zu applizierende Lacke. Zudem können sie in bestimmten Fällen dazu beitragen, die Eigenschaften von Metallblechen bei der Kaltumformung und bei der Anwendung von Tiefziehverfahren zu verbessern.Such phosphate layers not only improve the corrosion protection of the metal surfaces, but also increase the adhesion for paints to be applied to the surface. In certain cases, they can also help to improve the properties of metal sheets during cold forming and when using deep-drawing processes.

Speziell für die Phosphatierung von Metalloberflächen, die später mit Elektrotauchlacken beschichtet werden sollen, werden immer häufiger Zink-Calcium-Phosphatlösungen angewendet. Dabei haben Erfahrungswerte über die Zusammensetzung der Badlösungen einerseits und grundsätzliche Erkenntnisse über den Aufbau von Phosphatierungsschichten andererseits (A. Neuhaus und M. Gebhardt, Werkstoffe und Korrosion, 567 (1966)) die Lehre vermittelt, dass der Aufbau einheitlicher und geschlossener Phosphatierungsschichten nicht nur von der Zusammensetzung der Badlösungen, sondern auch von der Vorbehandlung der Rohbleche, der Aktivierung vor dem Phosphatier-Schritt, der Wahl eines geeigneten Beschleunigers und weiteren Verfahrens-Parametern abhängt.Zinc-calcium-phosphate solutions are increasingly being used especially for the phosphating of metal surfaces that are later to be coated with electrocoating materials. Experiences about the composition of the bathroom solutions on the one hand and basic knowledge about the structure of phosphating layers on the other (A. Neuhaus and M. Gebhardt, Werkstoffe und Korrosion, 567 (1966)) have conveyed the teaching that the construction of uniform and closed phosphating layers is not only of depends on the composition of the bath solutions, but also on the pretreatment of the raw sheets, the activation before the phosphating step, the choice of a suitable accelerator and other process parameters.

In der DE-A-1 521 818 werden unter anderem wässrige Phosphatierungslösungen offenbart, die als wesentliche Bestandteile 0,01 bis 1,5% Calcium-, 0,3 bis 6% Phosphat-, 0,02 bis 0,5% Zink-, 0,05 bis 3% Nitrat-, 0,015 bis 0,4% Nickel- und 0,001 bis 0,02% Nitrit-Ionen enthalten, eine Gesamtazidität im Bereich von 5 bis 50 Punkten aufweisen und die Phosphatierung galvanisierter Eisenmetalloberflächen gestatten.DE-A-1 521 818 discloses, inter alia, aqueous phosphating solutions which contain 0.01 to 1.5% calcium, 0.3 to 6% phosphate, 0.02 to 0.5% zinc as essential components. , 0.05 to 3% nitrate, 0.015 to 0.4% nickel and 0.001 to 0.02% nitrite ions, have an overall acidity in the range of 5 to 50 points and allow the phosphating of galvanized ferrous metal surfaces.

Als Beispiele werden unter anderem die folgenden Phosphatierungslösungen offenbart:The following phosphating solutions are disclosed as examples:

Lösung A: 0,11% Ca, 0,078% Zn, 0,995% P04, 0,048% Ni, 0,0396% N03, 0,002% N02, Punkte Gesamtsäure: 13,6;Solution A: 0.11% Ca, 0.078% Zn, 0.995% P0 4 , 0.048% Ni, 0.0396% N0 3 , 0.002% N0 2 , total acid points: 13.6;

Lösung B: 0,098% Ca, 0,043% Zn, 1,04% P04, 0,07% Ni, 0,486% N03, 0,002% NO2, Punkte Gesamtsäure: 14,8.Solution B: 0.098% Ca, 0.043% Zn, 1.04% P0 4 , 0.07% Ni, 0.486% N0 3 , 0.002% NO 2 , total acid points: 14.8.

Die in den Beispielen verwendeten Lösungen enthalten hohe Gehalte an Zink- und Calciumionen bei niedrigem Phosphationen-Gehalt; das Gewichtsverhältnis der Summe aus Zink- und Calciumionen zu Phosphationen liegt im Bereich von 1:3,5 bis 1:7,4. Die Temperatur der wässrigen Phosphatierungslösungen kann innerhalb weiter Grenzen schwanken, beispielsweise von etwa Raumtemperatur bis zu etwa 116°C. Im allgemeinen werden die besten Ergebnisse erzielt, wenn die wässrigen Phosphatierungslösungen bei einer Temperatur von mindestens etwa 38°C, im allgemeinen innerhalb des Bereiches von etwa 49 bis etwa 93 °C verwendet werden.The solutions used in the examples contain high levels of zinc and calcium ions with a low phosphate ion content; the weight ratio of the sum of zinc and calcium ions to phosphate ions is in the range from 1: 3.5 to 1: 7.4. The temperature of the aqueous phosphating solutions can vary within wide limits, for example from about room temperature to about 116 ° C. In general, the best results are obtained when the aqueous phosphating solutions are used at a temperature of at least about 38 ° C, generally within the range of about 49 to about 93 ° C.

Ein Nachteil der offenbarten Phosphatierungslösungen ist es jedoch, dass die Temperatur des Phosphatierungsschrittes relativ hoch sein muss, um eine wirtschaftlich vertretbare, kurze Applikationszeit der Lösungen erreichen zu können:

  • Bei Gesamteintauchzeiten von 1 bis 20 Sekunden liegen die Temperaturen zwischen 66 und 116°C.
A disadvantage of the disclosed phosphating solutions, however, is that the temperature of the phosphating step must be relatively high in order to be able to achieve an economically justifiable, short application time for the solutions:
  • With total immersion times of 1 to 20 seconds, the temperatures are between 66 and 116 ° C.

Gegenstand der DE-A-3 118 375 ist ein Verfahren zum Phosphatieren von Metallen sowie dessen Anwendung zur Vorbehandlung für die Elektrotauchlackierung. Hierbei werden die Metalloberflächen, insbesondere solche aus Eisen, Stahl und Zink, mit sauren, wässrigen, oxidationsmittelhaltigen Zinkphosphatlösungen in Berührung gebracht, die 0,4 bis 1,5 g/I Zn, 0 bis 1,3 g/I Ni und 10 bis 26 g/l P205 enthalten, wobei das Gewichtsverhältnis von Zn zu P205 auf einen Wert von (0,012 bis 0,12):1 und von Ni zu Zn auf einen Wert von (0 bis 1,5):1 eingestellt ist. Die Temperatur der Lösungen liegt vorzugsweise im Bereich von 30 bis 65°C. Insbesondere finden Lösungen Verwendung, die als Oxidationsmittel 2 bis 25 g/I N03, 1 bis 6 g/I CI03, 0,1 bis 2 g/I organische Nitroverbindung, 0,05 bis 0,5 g/l N02 und/oder 0,02 bis 0,1 g/I Peroxid (berechnet als H202) enthalten.DE-A-3 118 375 relates to a process for phosphating metals and its use for pretreatment for electrocoating. Here, the metal surfaces, in particular those made of iron, steel and zinc, are brought into contact with acidic, aqueous, oxidizing agent-containing zinc phosphate solutions which contain 0.4 to 1.5 g / l Zn, 0 to 1.3 g / l Ni and 10 to 26 g / l contain P 2 0 5 , the weight ratio of Zn to P 2 0 5 to a value of (0.012 to 0.12): 1 and of Ni to Zn to a value of (0 to 1.5): 1 is set. The temperature of the solutions is preferably in the range from 30 to 65 ° C. In particular, solutions are used which are 2 to 25 g / l N0 3 , 1 to 6 g / l CI0 3 , 0.1 to 2 g / l organic nitro compound, 0.05 to 0.5 g / l N0 2 and / or contain 0.02 to 0.1 g / l peroxide (calculated as H 2 0 2 ).

Die Lösungen können noch weitere Kationen enthalten, beispielsweise Calcium, Kupfer, Mangan, Kobalt, Magnesium; üblicherweise liegt ihr Gehalt jedoch nicht über 0,5 g/I. Um besonders dünne, feinkristalline Schichten zu erzeugen, empfiehlt sich die Anwendung von Aktivierungsmitteln, z. B. auf Titanphosphatbasis, im Vorspülbad oder in der letzten Reinigerstufe.The solutions can also contain other cations, for example calcium, copper, manganese, cobalt, magnesium; however, their content is usually not more than 0.5 g / l. In order to produce particularly thin, fine crystalline layers, the use of activating agents, e.g. B. on titanium phosphate basis, in the pre-rinse bath or in the last cleaning stage.

In der EP-A-45 110 wird ein Verfahren zur Herstellung von Phosphatüberzügen auf Eisen- oder Stahloberflächen mit einer wässrigen sauren Zinkphosphatlösung sowie dessen Anwendung auf die Vorbereitung von Metalloberflächen für die Kaltverformung beschrieben. Die Metalloberflächen werden hierbei mit Lösungen behandelt, die mindestens 0,3 Gewichtsprozent Zn, mindestens 0,3 Gewichtsprozent P04 und mindestens 0,75 Gewichtsprozent N03 oder eines gleichwirkenden Eisen (11) nicht oxidierenden Beschleunigers enthalten, wobei das Gewichtsverhältnis ZB:P04 grösser als 0,8 ist, das Verhältnis von Gesamtsäure zu freier Säure mindestens 5 beträgt und in welchen man durch geeignete Bemessung von C103 oder einem gleichwertigen Eisen (11) zu Eisen (111) oxidierenden Beschleuniger einen Eisen (11)-Gehalt von 0,04 bis 1 Gewichtsprozent einstellt. Derartige Lösungen können zusätzlich Calcium in Mengen von 0,1 bis 0,88 Gewichtsprozent enthalten; dabei soll das Gewichtsverhältnis Zn:Ca 1,5 bis 4 betragen. Die Temperatur der Lösungen liegt im Bereich von 35 bis 98 °C. Die zuvor gereinigten Metalloberflächen können einer Aktivierungsbehandlung, z.B. durch Heisswasserspülung oder mit einer Titanorthophosphatdispersion, unterworfen werden.EP-A-45 110 describes a process for the production of phosphate coatings on iron or steel surfaces with an aqueous acidic zinc phosphate solution and its use for the preparation of metal surfaces for cold working. The metal surfaces are treated with solutions containing at least 0.3 percent by weight Zn, at least 0.3 percent by weight P0 4 and at least 0.75 percent by weight N0 3 or an equivalent iron (11) non-oxidizing accelerator, the weight ratio ZB: P0 4th is greater than 0.8, the ratio of total acid to free acid is at least 5 and in which is adjusted by suitable measurement of C10 3 or an equivalent iron (11) to iron (111) oxidizing accelerator, an iron (11) content of 0.04 to 1 percent by weight. Such solutions can additionally contain calcium in amounts of 0.1 to 0.88 percent by weight; the weight ratio Zn: Ca should be 1.5 to 4. The temperature of the solutions is in the range from 35 to 98 ° C. The previously cleaned metal surfaces can be subjected to an activation treatment, for example by hot water rinsing or with a titanium orthophosphate dispersion.

Die DE-A-2 540 685 beschreibt gleichfalls ein Verfahren zur Herstellung von Phosphatüberzügen auf Metalloberflächen, insbesondere Eisen und Stahl, welches sich als Vorbereitung für die spanlose Kaltumformung bewährt hat. Hierbei kommen wässrige saure Zinkphosphatlösungen zum Einsatz, die Chlorat und Nitrat enthalten und ein Gewichtsverhältnis P205:Zn = 1:(0,8 bis 4) aufweisen. Bevorzugt sind Lösungen, die folgende Zusammensetzung aufweisen: mindestens 6 g/I Zink, mindestens 5 g/I P205, mindestens 1 g/I C103 und mindestens 8 g/I N03; Gesamtsäurepunktzahl: 20 bis 80, Gewichtsverhältnis P2O5:Zn:Cl03 = 1:(0,8 bis 4):(0,8 bis 6):(0,03 bis 2), Gewichtsverhältnis von freien P205:gesamt P205 = (0,2 bis 0,6): 1.DE-A-2 540 685 also describes a process for the production of phosphate coatings on metal surfaces, in particular iron and steel, which has proven itself as a preparation for non-cutting cold forming. Here, aqueous acidic zinc phosphate solutions are used which contain chlorate and nitrate and have a weight ratio P 2 0 5 : Zn = 1: (0.8 to 4). Solutions which have the following composition are preferred: at least 6 g / l zinc, at least 5 g / IP 2 0 5 , at least 1 g / l C10 3 and at least 8 g / l NO 3 ; Total acid number: 20 to 80, weight ratio P 2 O 5 : Zn: Cl0 3 = 1: (0.8 to 4) :( 0.8 to 6) :( 0.03 to 2), weight ratio of free P 2 0 5 : total P 2 0 5 = (0.2 to 0.6): 1.

Derartige Lösungen können zusätzlich mindestens 0,4 g/I Ca enthalten, wobei das Gewichtsverhältnis Ca:Zn = (0,04 bis 3):1 beträgt. Die Metalloberflächen werden mit solchen Lösungen bei Temperaturen zwischen 35 und 98°C ca. 5 bis 15 Minuten im Tauchen oder Fluten behandelt. Vor der Phosphatierungsbehandlung können die Metalloberflächen durch Vorspülen mit heissem Wasser oder mit Titanorthophosphatdispersionen aktiviert werden.Such solutions can additionally contain at least 0.4 g / l Ca, the weight ratio Ca: Zn = (0.04 to 3): 1. The metal surfaces are treated with such solutions at temperatures between 35 and 98 ° C for about 5 to 15 minutes in immersion or flooding. Before the phosphating treatment, the metal surfaces can be activated by pre-rinsing with hot water or with titanium orthophosphate dispersions.

Ein ähnliches Verfahren ist Gegenstand der DE-A-2 540 684. Die hier beschriebenen wässrigen, sauren Phosphatierungslösungen enthalten Zink, Phosphat und Nitrat und bilden autokatalytisch Nitrit. Hierbei soll im Phosphatierungsbad ein N02-Gehalt von mindestens 0,03 g/I aufrechterhalten, jedoch ein Anstieg auf mehr als 0,2 g/I durch Zusatz einer Nitrit-zerstörenden Substanz - beispielsweise Harnstoff, Amidosulfonsäure, Chlorat, Peroxid - unterbunden werden. Bevorzugte Lösungen enthalten: mindestens 6 g/l Zink, mindestens 5 g/I P205, mindestens 10 g/1 N03 und 0,03 bis 0,2 g/I N02; Gesamtsäurepunktzahl: 20 bis 80; Gewichtsverhältnis P2O5:Zn:NO3 = 1:(0,8 bis 4):(1,8 bis 6); Gewichtsverhältnis von freien P205:gesamt P205 = (0,2 bis 0,6):1. Auch diese Lösungen können zusätzlich mindestens 0,4 g/I Ca enthalten, jedoch nicht mehr als 3 Gewichtsteile Ca auf 1 Gewichtsteil Zn. Die Anwendungstemperaturen liegen hierbei im Bereich von 60 bis 90 °C.A similar process is the subject of DE-A-2 540 684. The aqueous, acidic phosphating solutions described here contain zinc, phosphate and nitrate and autocatalytically form nitrite. In this case, an N0 2 content of at least 0.03 g / l is to be maintained in the phosphating bath, but an increase to more than 0.2 g / l is to be prevented by adding a nitrite-destroying substance - for example urea, amidosulfonic acid, chlorate, peroxide . Preferred solutions contain: at least 6 g / l zinc, at least 5 g / IP 2 0 5 , at least 10 g / 1 N0 3 and 0.03 to 0.2 g / I N0 2 ; Total Acid Score: 20 to 80; Weight ratio P 2 O 5 : Zn: NO 3 = 1: (0.8 to 4) :( 1.8 to 6); Weight ratio of free P 2 0 5 : total P 2 0 5 = (0.2 to 0.6): 1. These solutions can also contain at least 0.4 g / l of Ca, but not more than 3 parts by weight of Ca per 1 part by weight of Zn. The application temperatures here are in the range from 60 to 90.degree.

Wässrige Lösungen für Phosphatier-Verfahren, die Zink-, Calcium-, Phosphat- und gegebenenfalls auch Nickel-lonen und zusätzlich H202 als Beschleuniger enthalten, werden in der BE-A-811 220 beschrieben. Die Anwendungstemperaturen derartiger Lösungen liegen jedoch auch relativ hoch. Im Verhältnis zum Phosphatgehalt ist der Gehalt an Zink- und Calciumionen sehr hoch.Aqueous solutions for phosphating processes which contain zinc, calcium, phosphate and optionally also nickel ions and additionally H 2 0 2 as accelerators are described in BE-A-811 220. However, the application temperatures of such solutions are also relatively high. In relation to the phosphate content, the content of zinc and calcium ions is very high.

Verfahren zur Phosphatierung von Metalloberflächen mittels saurer, Oxidationsmittel-haltiger Zinkphosphatlösungen, in denen ein vergleichsweise niedriger Zinkgehalt einem deutlich höheren Phosphatgehalt gegenübersteht und die weitere zweiwertige Metallionen, z.B. auch Ca2+- lonen, enthalten können, werden in der DE-B-2 232 067 und der DE-A-3 118 375 beschrieben. Mit dem Verfahren gemäss der DE-B-2 232 067 lassen sich zwar mit frischen Anwendungslösungen qualitativ hochwertige Phosphatschichten ausbilden; nach Durchlauf einer höheren Zahl von Blechen wird jedoch der Korrosionsschutz aufgrund unregelmässiger Phosphatier-Schichten qualitativ schlechter, z.T. bilden sich keine brauchbaren Schutzschichten mehr aus.Methods for phosphating metal surfaces by means of acidic, oxidizing agent-containing zinc phosphate solutions, in which a comparatively low zinc content contrasts with a significantly higher phosphate content and which can contain further divalent metal ions, for example also Ca 2 + ions, are described in DE-B-2 232 067 and DE-A-3 118 375. With the method according to DE-B-2 232 067, high-quality phosphate layers can be formed with fresh application solutions; After passing through a higher number of sheets, however, the corrosion protection becomes qualitatively poorer due to irregular phosphating layers, in some cases no more useful protective layers are formed.

Ein weiterer Nachteil der meisten bisher beschriebenen Verfahren ist darin zu sehen, dass die Qualität der im Phosphatierschritt ausgebildeten Schwermetallphosphat-Schichten in höchstem Masse von der entfettenden Vorbehandlung der Metalloberflächen wie auch von der Aktivierung abhängig ist. Insbesondere dem Aktivierungsschritt kommt insofern grosse Bedeutung zu, als er die Grundlage für die Haftung der späteren Phosphatschichten darstellt und damit die Qualität der sich bildenden Phosphat-Überzüge wesentlich beeinflusst. Die gewünschte Ausbildung dünner, feinkörnig-kristalliner Phosphatüberzüge ist nur nach hinreichender Aktivierung durch geeignete Aktivierungsmittel, z.B. phosphathaltige Aktivierungslösungen, möglich. Dabei ergibt sich insbesondere die Schwierigkeit, eine Stippenbildung zu vermeiden, die die Qualität der Phosphatier-Schicht nachteilig beeinflusst.Another disadvantage of most of the processes described so far is that the quality of the heavy metal phosphate layers formed in the phosphating step is highly dependent on the degreasing pretreatment of the metal surfaces and on the activation. The activation step in particular is of great importance insofar as it forms the basis for the adhesion of the later phosphate layers and thus significantly influences the quality of the phosphate coatings which form. The desired formation of thin, fine-grained, crystalline phosphate coatings can only be achieved after sufficient activation by suitable activating agents, e.g. Activation solutions containing phosphate are possible. This results in particular in the difficulty of avoiding speck formation, which adversely affects the quality of the phosphating layer.

Überraschend wurde nun gefunden, dass man dünne, feinkörnig-kristalline Zink-Calcium-Phosphat-Schichten hoher Homogenität schon bei niedriger Behandlungstemperatur erhält, wenn man Metalloberflächen mit sauren wässrigen Lösungen behandelt, die Zink-, Calcium- und Phosphationen, sowie einen oder mehrere Beschleuniger enthalten, wobei ein enger Bereich des pH-Wertes, ein bestimmtes Säureverhältnis, sowie ein vorgegebenes Gewichtsverhältnis der Summe an Calcium- und Zinkionen zu Phosphat-Ionen einzuhalten sind.Surprisingly, it has now been found that thin, fine-grained, crystalline zinc-calcium-phosphate layers of high homogeneity can be obtained even at a low treatment temperature if metal surfaces are treated with acidic aqueous solutions, the zinc, calcium and phosphate ions, and one or more accelerators contain, whereby a narrow range of the pH value, a certain acid ratio, as well as a predetermined weight ratio of the sum of calcium and zinc ions to phosphate ions are to be observed.

Die Erfindung betrifft daher ein Verfahren zum Phosphatieren von Metalloberflächen, insbesondere von Oberflächen aus Eisen, Stahl, Zink und/ oder Aluminium, zur Vorbehandlung derselben für eine nachfolgende Elektrotauchlackierung, insbesondere eine kathodische Elektrotauchlackierung, mittels einer sauren, Zink, Calcium, Phosphat und Beschleuniger sowie gegebenenfalls weitere Zusätze, wie Nickel oder Fluoride, enthaltenden Phosphatier-Lösung, wobei man die Oberflächen nach einer entfettenden Reinigung derselben ohne Aktivierungsschritt im Temperaturbereich von 30 bis 65 °C mit Lösungen in Kontakt bringt, für die die folgenden Bedingungen gelten:

  • a) Gehalt an Ca2+: mehr als 0,5 bis 1,5 g/l, b) Gehalt an Zn2+: 0,5 bis 1,5 g/l,
  • c) Gehalt an PO4 3-: 10 bis 50 g/l,
  • d) Gehalt an Beschleuniger
  • NO3 -: 0,5 bis 30 g/I und/oder
  • N02-: 0,01 bis 0,6 g/I und/oder
  • ClO3 -: 0,2 bis 10 g/I und/oder
  • organische Nitroverbindung: 0,1 bis 2 g/I und/ oder
  • anorganisches Peroxid bzw. H202: 0,01 bis 0,5 g/I
  • e) Gewichtsverhältnis Zn2+/Ca2+ = 1: (0,5 bis 1,5),
  • f) Gewichtsverhältnis (Ca2++Zn2+)/PO4 3- = 1: ( > 8 bis 40),
  • g) pH-Wert: 2,2 bis 3,8,
  • h)Verhältnis freie Säure/Gesamtsäure = 1:(10 bis 60)
The invention therefore relates to a method for phosphating metal surfaces, in particular surfaces made of iron, steel, zinc and / or aluminum, for pretreating the same for a subsequent electrocoating, in particular a cathodic electrocoating, using an acidic, zinc, calcium, phosphate and accelerator and optionally further additives, such as nickel or fluoride, containing phosphating solution, the surfaces being brought into contact with solutions after the degreasing cleaning thereof without an activation step in the temperature range from 30 to 65 ° C., for which the following conditions apply:
  • a) Ca 2+ content: more than 0.5 to 1.5 g / l, b) Zn 2+ content: 0.5 to 1.5 g / l,
  • c) PO 4 3- content: 10 to 50 g / l,
  • d) Accelerator content
  • NO 3 - : 0.5 to 30 g / l and / or
  • N0 2 -: 0.01 to 0.6 g / l and / or
  • ClO 3 - : 0.2 to 10 g / l and / or
  • organic nitro compound: 0.1 to 2 g / l and / or
  • inorganic peroxide or H 2 0 2 : 0.01 to 0.5 g / l
  • e) weight ratio Zn 2+ / Ca 2+ = 1: (0.5 to 1.5),
  • f) weight ratio (Ca 2+ + Zn 2+ ) / PO 4 3- = 1: (> 8 to 40),
  • g) pH: 2.2 to 3.8,
  • h) Free acid / total acid ratio = 1: (10 to 60)

Das erfindungsgemässe Verfahren eignet sich insbesondere für die Phosphatierung von Metalloberflächen aus Eisen, Stahl und Zink. Es sind jedoch auch Oberflächen aus Aluminium mit Zink-Calcium-Schichten mit dem erfindungsgemässen Verfahren zu überziehen.The method according to the invention is particularly suitable for the phosphating of metal surfaces made of iron, steel and zinc. However, surfaces made of aluminum with zinc-calcium layers are also to be coated with the method according to the invention.

Wie herausgefunden werden konnte, überziehen sich die behandelten Metalloberflächen mit einer Schicht von Dizinkcalciumphosphat-Dihydrat (Scholzit). Obwohl in die Phosphatier-Schicht Zink- und Calcium-lonen im Molverhältnis 2:1 eingebaut werden, ist es wesentlich für die Zusammensetzung der Badlösungen gemäss dem erfindungsgemässen Verfahren, dass sie Zink- und Calcium-lonen im Gewichtsverhältnis 1:0,5 bis 1:1,5, bevorzugt im Verhältnis 1:1 enthalten.As could be found, the treated metal surfaces are coated with a layer of dizinc calcium phosphate dihydrate (Scholzit). Although zinc and calcium ions are incorporated into the phosphating layer in a molar ratio of 2: 1, it is essential for the composition of the bath solutions according to the process according to the invention that they contain zinc and calcium ions in a weight ratio of 1: 0.5 to 1 : 1.5, preferably in a ratio of 1: 1.

Dazu werden den Lösungen geeignete wasserlösliche Zink- bzw. Calcium-Salze bzw. Lösungen zugesetzt, so dass der Gehalt an Zn2+ 0,5 bis 1,5 g/I Phosphatier-Lösung und der Gehalt an Ca2+ mehr als 0,5 bis 1,5 g/I Phosphatier-Lösung beträgt. Insbesondere werden ZnO, Phosphorsäure und Ca(NO3)2· 4H20 als Ausgangsverbindungen eingesetzt.For this purpose, suitable water-soluble zinc or calcium salts or solutions are added to the solutions, so that the Zn 2+ content is 0.5 to 1.5 g / l phosphating solution and the Ca 2+ content is more than 0. 5 to 1.5 g / l phosphating solution. In particular, ZnO, phosphoric acid and Ca (NO 3 ) 2 .4H 2 0 are used as starting compounds.

Der durch Phosphorsäure einstellbare Anteil an P043--lonen in den erfindungsgemässen Phosphatier-Lösungen liegt wesentlich höher: er bewegt sich im Bereich von 10 bis 50 g/I.The proportion of P043 ions in the phosphating solutions according to the invention which can be adjusted by means of phosphoric acid is considerably higher: it is in the range from 10 to 50 g / l.

Die angegebenen Mengen der die Hauptbestandteile der erfindungsgemässen Phosphatier- Lösung bildenden aktiven Ionen sind also dadurch charakterisiert, dass das Gewichtsverhältnis der Summe aus Calcium und Zink zu Phosphat immer im Bereich von 1 :grösser 8 bis 1:40 liegt. Dadurch wird gewährleistet, dass auf allen behandelten Metalloberflächen homogene Scholzit-Schichten gebildet werden; die Bildung von z. B. tertiärem Zinkphosphat-Tetrahydrat (Hopeit) oder Dizinkeisenphosphat-Tetrahydrat (Phosphophyllit), die zusammen mit Scholzit zu einer weniger homogenen und schlechter haftenden Schutzschicht führen würden, wird nicht beobachtet.The stated amounts of the active ions forming the main constituents of the phosphating solution according to the invention are therefore characterized in that the weight ratio of the sum of calcium and zinc to phosphate is always in the range from 1: greater than 8 to 1:40. This ensures that homogeneous Scholzit layers are formed on all treated metal surfaces; the formation of e.g. B. tertiary zinc phosphate tetrahydrate (Hopeit) or dizine iron phosphate tetrahydrate (phosphophyllite), which together with scholzite would lead to a less homogeneous and poorly adhering protective layer, is not observed.

Ein weiterer wesentlicher Verfahrensparameter ist darin zu sehen, dass das Molverhältnis von freier Säure zu Gesamtsäure (Säureverhältnis) auf Werte von 1:10 bis 1:60 einzustellen ist. Dies bedeutet insbesondere, dass ein relativ niedriger Wert für die Konzentration an freier Säure besonders wichtig für die Ausbildung guter Scholzit-Schichten ist.Another essential process parameter is the fact that the molar ratio of free acid to total acid (acid ratio) has to be set to values from 1:10 to 1:60. This means in particular that a relatively low value for the concentration of free acid is particularly important for the formation of good scholzite layers.

Als beschleunigende Oxidationsmittel werden den Phosphatierbad-Lösungen für das Verfahren gemäss der Erfindung Nitrat-Ionen in einer Menge von 0,5 bis 30 g/I, Nitrit-Ionen in einer Menge von 0,01 bis 0,6 g/l, Chlorat-lonen in einer Menge von 0,2 bis 10 g/I, organische Nitroverbindungen in einer Menge von 0,1 bis 2 g/I und/oder anorganische Peroxide bzw. H202 in einer Menge von 0,01 bis 0,5 g/I Badlösung zugesetzt.As accelerating oxidizing agents, the phosphating bath solutions for the process according to the invention are nitrate ions in an amount of 0.5 to 30 g / l, nitrite ions in an amount of 0.01 to 0.6 g / l, chlorate Ions in an amount of 0.2 to 10 g / l, organic nitro compounds in an amount of 0.1 to 2 g / l and / or inorganic peroxides or H 2 0 2 in an amount of 0.01 to 0.5 g / l bath solution added.

Sollen nach dem erfindungsgemässen Verfahren Aluminiumflächen phosphatiert werden, so können den Badlösungen einfache und/oder komplexe Fluoride in einer Menge von 0,01 bis 2 g/I zugesetzt werden, um auch kleinste Mengen von Aluminium, die aus der Metalloberfläche in das Bad treten und seine Wirksamkeit beeinträchtigen könnten, durch Fluorid-lonen zu komplexieren.If aluminum surfaces are to be phosphated by the process according to the invention, simple and / or complex fluorides can be added to the bath solutions in an amount of 0.01 to 2 g / l, including the smallest amounts of aluminum which enter the bath from the metal surface and its effectiveness could be compromised by complexing with fluoride ions.

Die Phosphatier-Lösungen, mit denen Metalloberflächen entsprechend dem erfindungsgemässen Verfahren phosphatiert werden, können auch weitere Metall-lonen enthalten, z.B. Ni2+.IhrGe- halt liegt im Bereich von 0,01 bis 1,5 g/i Badlösung.The phosphating solutions with which metal surfaces are phosphated according to the method according to the invention can also contain further metal ions, e.g. Ni2 + .Your content is in the range of 0.01 to 1.5 g / i bath solution.

Die Behandlung der Eisen-, Stahl-, Zink- und/ oder Aluminiumoberflächen gemäss dem vorliegenden Verfahren kann im Spritzen, Tauchen oder auch im Fluten erfolgen; es sind jedoch auch kombinierte Verfahren, wie z.B. Spritztauchen mit gleich gutem Erfolg anwendbar. Die Zeiten, während denen die Phosphatierlösungen mit den Metalloberflächen in Kontakt stehen, liegen zwischen 60 und 240 sec. Sie betragen z. B. für Spritzverfahren zwischen 60 bis 180 sec und für das Tauchen 90 bis 240 sec. Es sind jedoch auch wesentlich kürzere Behandlungszeiten möglich.The treatment of the iron, steel, zinc and / or aluminum surfaces according to the present method can be carried out by spraying, dipping or flooding; however, they are also combined processes, e.g. Spray diving applicable with equally good success. The times during which the phosphating solutions are in contact with the metal surfaces are between 60 and 240 seconds. B. for spraying between 60 to 180 sec and for diving 90 to 240 sec. However, much shorter treatment times are possible.

Die Metalloberflächen werden erfindungsgemäss mit den Phosphatierlösungen im Temperaturbereich von 30 bis 65°C behandelt. Bevorzugt werden Temperaturen zwischen 48 und 57 °C angewendet.According to the invention, the metal surfaces are treated with the phosphating solutions in the temperature range from 30 to 65 ° C. Temperatures between 48 and 57 ° C are preferably used.

Einer der wesentlichen Vorteile des erfindungsgemässen Verfahrens ist es, dass die Ausbildung der Scholzit-Schichten auf den Metalloberflächen völlig unabhängig davon erfolgt, welche Art von Reinigung dem Phosphatier-Schritt vorangegangen ist. Bei Anwendung des erfindungsgemässen Verfahrens besteht also völlige Freiheit hinsichtlich der Wahl der Entfettungs- und Reinigungsmittel.One of the main advantages of the method according to the invention is that the formation of the scholzite layers on the metal surfaces takes place completely independently of the type of cleaning which preceded the phosphating step. When using the method according to the invention there is complete freedom with regard to the choice of degreasing and cleaning agents.

Ein weiterer Vorteil ist darin zu sehen, dass besonders dünne, feinkörnig-kristalline Phosphatschichten auch ohne Anwendung von Aktivierungsmitteln erhalten werden, wie sie bei bisher bekannten Verfahren üblich waren. Dies erspart nicht nur mindestens einen der Phosphatierung vorausgehenden Verfahrensschritt, sondern auch die dafür notwendigen Rohstoffe, wie z.B. Titanphosphate, die als Aktivierungsmittel Anwendung finden.Another advantage can be seen in the fact that particularly thin, fine-grained crystalline phosphate layers are obtained without the use of activating agents, as was customary in previously known processes. This not only saves at least one process step prior to phosphating, but also the necessary raw materials, such as Titanium phosphates, which are used as activating agents.

Entsprechend dem Verfahren der vorliegenden Erfindung werden ausgezeichnete Schutzschichten mit einer Schichtdicke zwischen 0,5 und 5 µm erhalten, die als Grundlage für Elektrotauchlacke, insbesondere für kathodische Elektrotauchlacke, wie sie in der Autoindustrie zunehmend verwendet werden, hervorragend geeignet sind. Die erfindungsgemäss erhaltenen Phosphatierschichten sind jedoch auch als Grundlage für andere organische Oberflächen-Schutzschichten geeignet.According to the method of the present invention, excellent protective layers with a layer thickness between 0.5 and 5 μm are obtained, which are used as the basis for electrocoating materials are particularly suitable for cathodic electrocoat materials, as are increasingly used in the automotive industry. However, the phosphating layers obtained according to the invention are also suitable as the basis for other organic surface protective layers.

Die Erfindung wird durch die nachstehenden Beispiele näher erläutert.The invention is illustrated by the examples below.

Die erfindungsgemässen Phosphatierlösungen wurden nach an sich bekannten Verfahren dadurch hergestellt, dass man die gewünschten Komponenten, insbesondere Zinkoxid, Phosphorsäure und Calciumnitrat-Tetrahydrat enthaltende Konzentrate, Salze und Lösungen vereinigte und mit Wasser auf die erfindungsgemässen Konzentrationen verdünnte.The phosphating solutions according to the invention were prepared by processes known per se by combining the desired components, in particular concentrates, salts and solutions containing zinc oxide, phosphoric acid and calcium nitrate tetrahydrate and diluting them with water to the concentrations according to the invention.

Beispiel 1example 1

Es wurde eine Phosphatierungslösung hergestellt, die

  • 1,0 gl-1 Ca2+
  • 1,2 gl-1 Zn2+
  • 29,5 gl-1 PO4 3-
  • 1,0 gl-1 ClO3 -
  • 3,2 gl-1 N03
  • 0,1 gl-1 N02 -
A phosphating solution was prepared that
  • 1.0 gl-1 C a2 +
  • 1.2 gl -1 Zn 2+
  • 29.5 gl -1 PO 4 3-
  • 1.0 gl -1 ClO 3 -
  • 3.2 gl -1 N03
  • 0.1 gl -1 N0 2 -

enthielt.contained.

Die Phosphatierlösung hatte folgende Kenndaten:

  • pH-Wert: ca. 3,1
  • Säureverhältnis: ca. 1:19
  • (Ca2+ + Zn2+):P04 3- = 1:13,4
The phosphating solution had the following characteristics:
  • pH: approx.3.1
  • Acid ratio: approx. 1:19
  • (Ca 2+ + Zn 2+ ): P0 4 3- = 1: 13.4

Stahlbleche, die zuvor mit einer alkalischen Reinigungslösung bei 50°C während 3 Minuten durch Tauchbehandlung gereinigt und mit Wasser gespült worden waren, wurden mit der vorgenannten Phosphatierlösung 4 Minuten bei 55°C im Tauchen behandelt. Anschliessend wurde mit Wasser und mit destilliertem Wasser gespült und getrocknet.Steel sheets which had previously been immersed in an alkaline cleaning solution at 50 ° C. for 3 minutes and rinsed with water were treated with the aforementioned phosphating solution for 4 minutes at 55 ° C. in immersion. It was then rinsed with water and with distilled water and dried.

Die erzeugten Phosphatschichten waren feinkristallin und geschlossen.The phosphate layers produced were finely crystalline and closed.

Danach wurden die Bleche mit einem kathodischen Elektrotauchlack beschichtet und 20 Minuten durch Erwärmen bei 185°C getrocknet. Die Trockenfilmdicke des Lackes betrug 18 µm.The sheets were then coated with a cathodic electrocoating material and dried for 20 minutes by heating at 185 ° C. The dry film thickness of the lacquer was 18 µm.

Anschliessend wurden die Bleche mit einem Einzelschnitt nach DIN 53167 versehen und dem Salzsprühtest gemäss DIN 50 021 während einer Zeitdauer von 480 h unterworfen. Die Auswertung nach DIN 53 167 ergab eine Unterwanderung von <0,1 mm.The sheets were then provided with a single cut in accordance with DIN 53167 and subjected to the salt spray test in accordance with DIN 50 021 for a period of 480 h. The evaluation according to DIN 53 167 showed an infiltration of <0.1 mm.

Das Beispiel veranschaulicht, dass das erfindungsgemässe Verfahren gute Phosphatschichten entstehen lässt.The example illustrates that the process according to the invention produces good phosphate layers.

Beispiel 2Example 2

Es wurde eine Phosphatierlösung hergestellt, die

  • 0,6 gl-1 Ca 2+
  • 0,7 gl-1 Zn 2+
  • 22,6 gl-1 PO4 3-
  • 0,3 gl-1 Ni 2+
  • 2,7 gl-1 N03 -
  • 0,5 gl-1 F-
  • 0,1 gl-1 N02 -
A phosphating solution was prepared that
  • 0.6 gl -1 Ca 2+
  • 0.7 gl -1 Zn 2+
  • 22.6 gl -1 PO 4 3-
  • 0.3 gl -1 Ni 2+
  • 2.7 gl -1 N0 3 -
  • 0.5 gl -1 F -
  • 0.1 gl -1 N0 2 -

enthielt.contained.

Die Phosphatierlösung hatte folgende Kenndaten:

  • pH-Wert: ca. 3,3
  • Säureverhältnis: ca. 1:39
  • (Ca2++Zn2+):PO4 3- = 1:17,4
The phosphating solution had the following characteristics:
  • pH: approx.3.3
  • Acid ratio: approx. 1:39
  • (Ca 2+ + Zn 2+ ): PO 4 3- = 1: 17.4

Stahlbleche, die zuvor mit einer alkalischen Reinigungslösung bei 45°C während 60 Sekunden durch Spritzbehandlung gereinigt worden waren, wurden mit der vorgenannten Phosphatierlösung 90 Sekunden bei 48°C im Spritzen behandelt. Anschliessend wurde mit Wasser und mit destilliertem Wasser gespült und durch Pressluft getrocknet.Steel sheets which had previously been spray-cleaned with an alkaline cleaning solution at 45 ° C. for 60 seconds were sprayed with the aforementioned phosphating solution for 90 seconds at 48 ° C. It was then rinsed with water and distilled water and dried by compressed air.

Die erzeugten Phosphatschichten waren feinkristallin und geschlossen.The phosphate layers produced were finely crystalline and closed.

Danach wurden die Bleche mit einem kathodischen Elektrotauchlack beschichtet und 20 Minuten durch Erwärmen bei 185°C getrocknet. Die Trockenfilmdicke des Lackes betrug 18 µm.The sheets were then coated with a cathodic electrocoating material and dried for 20 minutes by heating at 185 ° C. The dry film thickness of the lacquer was 18 µm.

Anschliessend wurden die Bleche mit einem Einzelschnitt nach DIN 53 167 versehen und dem Salzsprühtest gemäss DIN 50 021 während einer Zeitdauer von 480 h unterworfen. Die Auswertung nach DIN 53 167 ergab eine Unterwanderung von <0,1 mm.The sheets were then provided with a single cut in accordance with DIN 53 167 and subjected to the salt spray test in accordance with DIN 50 021 for a period of 480 h. The evaluation according to DIN 53 167 showed an infiltration of <0.1 mm.

Das Beispiel veranschaulicht, dass das erfindungsgemässe Verfahren gute Phosphatschichten entstehen lässt.The example illustrates that the process according to the invention produces good phosphate layers.

Beispiel 3Example 3

Es wurde eine Phosphatierlösung hergestellt, die

  • 1,3 gl-1 Ca 2+
  • 1,3 gl-1 Zn 2+
  • 21,2 gl-1 PO4 3-
  • 1,0 gl-1 Ni2+
  • 2,2 gl-1 CI03 -
  • 0,6 gl-1 Natriumnitrobenzolsulfonat
A phosphating solution was prepared that
  • 1.3 gl -1 Ca 2+
  • 1.3 gl -1 Zn 2+
  • 21.2 gl -1 PO 4 3-
  • 1.0 gl -1 Ni 2+
  • 2.2 gl -1 CI0 3 -
  • 0.6 gl -1 sodium nitrobenzenesulfonate

enthielt.contained.

Die Phosphatierlösung hatte folgende Kenndaten:

  • pH-Wert: ca. 2,9
  • Säureverhältnis: ca. 1:18,6
  • (Ca2++Zn2+):P04 3- = 1:8,2
The phosphating solution had the following characteristics:
  • pH: approx.2.9
  • Acid ratio: approx. 1: 18.6
  • (Ca 2+ + Zn 2+ ): P0 4 3- = 1: 8.2

Elektrolytisch verzinkte Stahlbleche, die zuvor mit einer alkalischen Reinigungslösung bei 50°C während 3 Minuten durch Tauchbehandlung gereinigt und mit Wasser gespült worden waren, wurden mit der vorgenannten Phosphatierlösung 3 Minunten bei 57°C im Tauchen behandelt. Anschliessend wurde mit Wasser und mit destilliertem Wasser gespült und durch Pressluft getrocknet.Electrolytically galvanized steel sheets, which had been previously cleaned with an alkaline cleaning solution at 50 ° C. for 3 minutes by immersion treatment and rinsed with water, were treated with the aforementioned phosphating solution for 3 minutes at 57 ° C. while immersing. It was then rinsed with water and distilled water and dried by compressed air.

Die erzeugten Phosphatschichten waren feinkristallin und geschlossen.The phosphate layers produced were finely crystalline and closed.

Danach wurden die Bleche mit einem kathodischen Elektrotauchlack beschichtet und 20 Minuten durch Erwärmen bei 185°C getrocknet. Die Trockenfilmdicke des Lackes betrug 18 µm.The sheets were then coated with a cathodic electrocoating material and dried for 20 minutes by heating at 185 ° C. The dry film thickness of the lacquer was 18 µm.

Anschliessend wurden die Bleche mit einem Einzelschnitt nach DIN 53 167 versehen und dem Salzsprühtest gemäss DIN 50 021 während einer Zeitdauer von 480 h unterworfen. Die Auswertung nach DIN 53167 ergab eine Unterwanderung von <0,1 mm.The sheets were then provided with a single cut according to DIN 53 167 and the salt spray test according to DIN 50 021 during one Subjected to a duration of 480 h. The evaluation according to DIN 53167 showed an infiltration of <0.1 mm.

Das Beispiel veranschaulicht, dass das erfindungsgemässe Verfahren gute Phosphatschichten entstehen lässt.The example illustrates that the process according to the invention produces good phosphate layers.

Beispiel 4Example 4

Es wurde eine Phosphatierlösung hergestellt, die

  • 1,0 gl-1 Ca 2+
  • 1,4 gl-1 Zn 2+
  • 26,6 gl-1 PO4 3-
  • 3,2 gl-1 N03 -
  • 0,1 gl-1 N02 -
A phosphating solution was prepared that
  • 1.0 gl -1 Ca 2+
  • 1.4 gl -1 Zn 2+
  • 26.6 gl -1 PO 4 3-
  • 3.2 gl -1 N0 3 -
  • 0.1 gl -1 N0 2 -

enthielt.contained.

Die Phosphatierlösung hatte folgende Kenndaten:

  • pH-Wert: ca. 3,6
  • Säureverhältnis: ca. 1:48
  • (Ca2+ +Zn2+):PO4 3- = 1:11,1.
The phosphating solution had the following characteristics:
  • pH: approx.3.6
  • Acid ratio: approx. 1:48
  • (Ca 2+ + Zn 2+ ): PO 4 3- = 1: 11.1.

Stahlbleche, die zuvor mit einer alkalischen Reinigungslösung bei 45 °C während 60 Sekunden durch Spritzbehandlung gereinigt worden waren, wurden mit der vorgenannten Phosphatierlösung 120sec. bei 35°C im Spritzen behandelt. Anschliessend wurde mit Wasser und mit destilliertem Wasser gespült und durch Pressluft getrocknet.Steel sheets which had previously been spray-treated with an alkaline cleaning solution at 45 ° C. for 60 seconds were washed with the aforementioned phosphating solution 120sec. sprayed at 35 ° C. It was then rinsed with water and distilled water and dried by compressed air.

Die erzeugten Phosphatschichten waren feinkristallin und geschlossen.The phosphate layers produced were finely crystalline and closed.

Danach wurden die Bleche mit einem kathodischen Elektrotauchlack beschichtet und 20 Minuten durch Erwärmen bei 185°C getrocknet. Die Trockenfilmdicke des Lackes betrug 18 µm.The sheets were then coated with a cathodic electrocoating material and dried for 20 minutes by heating at 185 ° C. The dry film thickness of the lacquer was 18 µm.

Anschliessend wurden die Bleche mit einem Einzelschnitt nach DIN 53 167 versehen und dem Salzsprühtest gemäss DIN 50 021 während einer Zeitdauer von 480 h unterworfen. Die Auswertung nach DIN 53 167 ergab eine Unterwanderung von 0,2 mm.The sheets were then provided with a single cut in accordance with DIN 53 167 and subjected to the salt spray test in accordance with DIN 50 021 for a period of 480 h. The evaluation according to DIN 53 167 showed an infiltration of 0.2 mm.

Das Beispiel veranschaulicht, dass das erfindungsgemässe Verfahren gute Phosphatschichten entstehen lässt.The example illustrates that the process according to the invention produces good phosphate layers.

VergleichsbeispielComparative example

Gemäss der DE-A-1 521 818, S. 12, wurde die Lösung B hergestellt.According to DE-A-1 521 818, p. 12, solution B was prepared.

Stahlbleche, die zuvor mit einer alkalischen Reinigungslösung bei 72 °C während 30 sec gereinigt worden waren, wurden mit der vorgenannten Phosphatierungslösung 60 sec bei 66°C im Spritzen behandelt. Anschliessend wurde mit Wasser und mit destilliertem Wasser gespült und durch Pressluft getrocknet. Die erzeugten Phosphatschichten waren grob kristallin und nicht ganz geschlossen.Steel sheets which had previously been cleaned with an alkaline cleaning solution at 72 ° C. for 30 seconds were sprayed with the aforementioned phosphating solution for 60 seconds at 66 ° C. It was then rinsed with water and distilled water and dried by compressed air. The phosphate layers produced were roughly crystalline and not completely closed.

Danach wurden die Bleche mit einem kathodischen Elektrotauchlack beschichtet und 20 min durch Erwärmen bei 185°C getrocknet. Die Trokkenfilmdicke des Lackes betrug 18 µm.The sheets were then coated with a cathodic electrocoating material and dried by heating at 185 ° C. for 20 minutes. The dry film thickness of the lacquer was 18 μm.

Anschliessend wurden die Bleche mit einem Einzelschnitt nach DIN 53 167 versehen und dem Salzsprühtest gern. DIN 50 021 während einer Zeitdauer von 480 h unterworfen. Die Auswertung nach DIN 53 167 ergab eine Unterwanderung von 4 bis 6 mm.The sheets were then provided with a single cut according to DIN 53 167 and were happy to do the salt spray test. Subject to DIN 50 021 for a period of 480 h. The evaluation according to DIN 53 167 showed an infiltration of 4 to 6 mm.

Das Vergleichsbeispiel veranschaulicht, dass im Gegensatz zu den erfindungsgemässen Beispielen ein deutlich verminderter Korrosionsschutz erreicht wird.The comparative example illustrates that, in contrast to the examples according to the invention, significantly reduced corrosion protection is achieved.

Claims (6)

1. A process for phosphating metal surfaces, particularly surfaces of iron, steel, zinc and/or aluminium, for the pretreatment thereof for subsequent painting by electrodeposition, particularly cathodic electrodeposition, using an acidic phosphating solution containing zinc, calcium, phosphate and accelerators and, optionally, further additions, such as nickel or fluorides, the surfaces - after degreasing and without activation - being brought into contact at 30 to 65°C with solutions satisfying the following requirements:
a) content of Ca2+: more than 0.5 to 1.5 g/l,
b) content of Zn2+: 0.5 to 1.5 g/l,
c) content of P04 3-: 10 to 50 g/l,
d) content of accelerator
NO3 -: 0.5 to 30 g/I and/or
NO2 -: 0.01 to 0.6 g/I and/or
ClO3 -: 0.2 to 10 g/I and/or organic nitro compound: 0.1 to 2 g/I and/or inorganic peroxide or H202: 0.01 to 0.5 g/I,
e) ratio by weight Zn2+:Ca2+ = 1:(0.5 to 1.5),
f) ratio by weight (Ca2+ +Zn2+):P04 3- = 1:(> 8 to 40),
g) pH value: 2.2 to 3.8,
h) ratio of free acid to total acid = 1: (10 to 60)
2. A process as claimed in claim 1, characterized in that the phosphating solutions have a ratio by weight of Zn2+ to Ca2+ of 1:1.
3. A process as claimed in claim 1 or 2, characterized in that the phosphating solutions have an Ni2+ content of from 0.01 to 1.5 g/I.
4. A process as claimed in claim 1 or 2, characterized in that the phosphating solutions have a content of simple and/or complex fluorides of from 0.01 to 2 g/l.
5. Process as claimed in claims 1 to 4, characterized in that the metal surfaces are brought into contact with the phosphating solutions at a temperature in the range from 48 to 57°C.
6. A process as claimed in claims 1 to 5, characterized in that the metal surfaces are brought into contact with the phosphating solutions by immersion, spraying, flooding or by a combination thereof.
EP85102057A 1984-03-01 1985-02-25 Process for the zinc-calcium phosphatizing of metal surfaces at a low treating temperature Expired EP0155547B1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT85102057T ATE39135T1 (en) 1984-03-01 1985-02-25 PROCESS FOR ZINC-CALCIUM PHOSPHATION OF METAL SURFACES AT LOW TREATMENT TEMPERATURE.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19843407513 DE3407513A1 (en) 1984-03-01 1984-03-01 METHOD FOR ZINC-CALCIUM PHOSPHATION OF METAL SURFACES AT LOW TREATMENT TEMPERATURE
DE3407513 1984-03-01

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JP2636919B2 (en) * 1989-01-26 1997-08-06 日本パーカライジング株式会社 Lubrication treatment method for cold plastic working of steel
JPH0375379A (en) * 1989-05-15 1991-03-29 Nippon Paint Co Ltd Coated product, production thereof, concentrated phosphating agent and concentrated treating agent for replenishment
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JPS60208479A (en) 1985-10-21
CA1245951A (en) 1988-12-06
US4622078A (en) 1986-11-11
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EP0155547A1 (en) 1985-09-25
DE3566683D1 (en) 1989-01-12

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