KR102126746B1 - The electro-galvanizing method of the steel material for reducing wastewater and hydrogen embrittlement with using eco-friendly composition - Google Patents

Abstract

In the present invention, the bath step of immersing the steel material to be plated in water at 60 ~ 80 ℃; Contains Linear Alkyl Benzene Sulfonic Acid, Complex Organic-Inorganic Acid, Ammonium Chloride, Sodium Chloride, C9-11 Alcohol Ethoxylate (Alcohols, C9-11, ethoxylated) and Water A process composition; a immersed steel material to be plated in a process composition solution, which is a diluted solution diluted in water; and then washed by ultrasonic treatment; A neutralization step of washing the steel material at least once or more and then neutralizing the steel material by immersing it in an alkali solution; And plating step of performing electro-galvanization on the neutralized steel material; as it excludes the use of sulfuric acid, hydrochloric acid, nitric acid, to prevent hydrogen embrittlement of the steel material, as well as without the generation of waste water Provided is a method for electro galvanizing a steel material that can be electro galvanized in a simple process within a time.

Description

The electro-galvanizing method of steel materials that reduces the generation of wastewater and hydrogen embrittlement in the process using an environmentally friendly process composition{THE ELECTRO-GALVANIZING METHOD OF THE STEEL MATERIAL FOR REDUCING WASTEWATER AND HYDROGEN EMBRITTLEMENT WITH USING ECO-FRIENDLY COMPOSITION}

The present invention relates to an electrolytic zinc plating method for preventing hydrogen embrittlement of steel materials using an environment-friendly process composition. Specifically, the present invention relates to an electro zinc plating method using an eco-friendly process composition that does not contain hydrochloric acid, sulfuric acid, nitric acid, and the like.

The electrolytic zinc plating is carried out for the purpose of preventing corrosion of steel by using a combination of zinc and iron by a sacrificial method, and zinc is corroded and iron is corroded.

In general, electro zinc plating is a step of degreasing and washing the steel material by immersing the steel material to be plated in a solution composed of an alkali component, a surfactant, etc. for a certain period of time, washing the steel material multiple times, sulfuric acid, hydrochloric acid Immersing the steel material to be plated in a solution composed of a certain amount of time for a period of time to derust and wash the steel material, washing the steel material multiple times, and performing electro zinc plating on the degreased and washed steel material. step; Activating the electrogalvanized steel material by immersing the electrogalvanized steel material in a solution composed of nitric acid for a period of time; It is implemented according to a series of processes including, for example.

For example, in Korean Patent No. 10-0767761, cast iron to be plated in an acid solution mixed at a ratio of 10% by weight sulfuric acid, 5% by weight hydrochloric acid, 10% by weight surfactant, and 75% by weight of water for 15 to 20 minutes. After the acid degreasing step to immerse, and after washing the cast iron that has been subjected to the acid degreasing process, soak in 5% aqueous sodium silicate solution for 15 to 20 minutes to neutralize the acid component remaining in the cast iron, and to wash the neutralized cast iron again with water. After pickling, rinse with 5% sulfuric acid solution for 5 to 7 minutes to wash, and after washing the cast iron washed with sulfuric acid solution with water, ammonium chloride and zinc chloride are 200 g/L and 50 g/L, respectively. Disclosed is an electro zinc plating method of cast iron, including a zinc plating step in which electro zinc plating is performed for 25 to 30 minutes in a plating tank filled with a plating solution mixed at a ratio, and the like.

In addition, in Korean Patent Publication No. 10-2003-0057243, in the pickling process of a continuous electroplating line, 5 to 30% by weight of cloconic acid in a hydrochloric acid solution, 5 to 40% by weight of hydrogen peroxide, 3 to 15% by weight of sodium phosphate, an organic catalyst 5% or less, and the rest, 0.5 to 10% of the acid pickling accelerator composed of water is added to a hydrochloric acid solution having a concentration of 12% or less in a volume ratio, and discloses a method of manufacturing an electrolytic galvanized steel sheet.

According to the conventional process including the above-mentioned patent, sulfuric acid and hydrochloric acid are essentially used for the purpose of rust removal, washing, degreasing, etc. of the steel material to be plated in the course of performing electrolytic zinc plating. There was a problem intensifying the hydrogen embrittlement of steel materials. Accordingly, after the electrolytic zinc plating, there was a problem that the strength, tensile strength, durability, impact resistance, etc. of the steel material were deteriorated.

In addition, sulfuric acid, hydrochloric acid, nitric acid, and the like used in the electrolytic zinc plating process are components harmful to the human body and the environment that must be subjected to wastewater treatment, and according to the existing electrogalvanizing process using the components, the process for wastewater treatment This must have been done. Accordingly, not only the process cost is increased, but also the process time is increased, there is a problem that the economic efficiency is lowered.

In addition, according to the conventional process including the above-mentioned patent, it can be seen that it takes a very long time for processes such as rust removal, washing and degreasing of the steel material to be plated. Specifically, in the registered patent No. 10-0767761, it can be seen that it takes up to 47 minutes before galvanizing. That is, according to the conventional process, it can be seen that the electrolytic zinc plating process itself takes a long time.

Therefore, as an electro-galvanizing process that solves the above problems, the use of sulfuric acid, hydrochloric acid, nitric acid, etc. is excluded to prevent hydrogen embrittlement of steel materials. There is a need to develop an electrolytic zinc plating process, which is significantly improved by minimizing economic efficiency.

Republic of Korea Registered Patent No. 10-0767761 Republic of Korea Patent Publication No. 10-2003-0057243

The object of the present invention is to prevent the use of sulfuric acid, hydrochloric acid, nitric acid to prevent hydrogen embrittlement of the steel material, as well as to significantly reduce the generation of waste water, can be carried out by electrolytic zinc plating in a short process in a short time, steel material It is to provide a method for electro zinc plating.

The object of the present invention is not limited to the technical problems as described above, and another technical problem may be derived from the following description.

In order to achieve the above object, the present invention is a bath step of immersing the steel material to be plated in water of 60 ~ 80 ℃; Washing step of immersing the steel material in the composition for the process, followed by ultrasonic treatment; A neutralization step of washing the steel material at least once or more and then neutralizing the steel material by immersing it in an alkali solution; And a plating step of performing electro zinc plating on the neutralized steel material, wherein the composition for the process is linear alkylbenzene sulfonic acid, complex organic-inorganic acid, ammonium chloride, sodium chloride (Sodium Chloride), C9-11 alcohol ethoxylate (Alcohols, C9-11, ethoxylated) and a process composition comprising water; dilution of water in dilution, water, electrolytic zinc of steel material using eco-friendly process composition A plating method is provided.

In the washing step, the temperature of the composition for the process is 45 to 52°C, and the steel material is immersed in the composition for the process, and then ultrasonicated for 45 to 80 seconds.

The composition for the process is based on the total weight of the composition for the process, linear alkyl benzene sulfonic acid (Linear Alkyl Benzene Sulfonic Acid) 1 to 5% by weight, complex organic-inorganic acid 28 to 35% by weight, ammonium chloride (Ammonium Chloride) 5 to 13% by weight %, Sodium Chloride 1 to 7% by weight, C9-11 alcohol ethoxylate (Alcohols, C9-11, ethoxylated) 1 to 4% by weight and residual water.

The complex organic-inorganic acid is formic acid (Acic acid), propionic acid (Propionic acid), butyric acid (Butyric acid), valeric acid (Valeric acid), capric acid (Caproic acid), acrylic acid (Acrylic acid), Crotonic acid, oxalic acid, malonic acid, succinic acid, glutaric acid, cinnamic acid, glycolic acid, citric acid Citric acid) and an organic acid comprising two or more selected from the group consisting of levulinic acid (Levulinic acid); And an inorganic acid including at least one selected from the group consisting of phosphoric acid and phosphorous acid.

The complex organic-inorganic acid may include the citric acid, the levulinic acid, and the phosphoric acid in a weight ratio of 1: 0.1 to 0.5: 3 to 5.

After the plating step, an activation step of immersing the electro-galvanized steel material in the composition for the process to activate it may further include.

In the activation step, the electro-galvanized steel material may be immersed in the composition for the process for 5 to 20 seconds.

According to the electro-galvanizing method of the present invention, as the use of sulfuric acid and hydrochloric acid is excluded during the electro-galvanizing process, hydrogen embrittlement generated in the steel material after electro-galvanizing can be prevented. In particular, according to the present invention, the use of hydrochloric acid corresponding to the main material for generating hydrogen embrittlement of the steel material is excluded, and hydrogen embrittlement generated in the steel material after electrogalvanization can be prevented.

In addition, according to the electrolytic zinc plating method of the present invention, not only hydrogen embrittlement of the steel material is prevented, but also the adhesion between the steel material and the zinc plating layer by electrogalvanization may be excellent.

In addition, according to the electrogalvanizing method of the present invention, as the use of sulfuric acid, hydrochloric acid, nitric acid, etc. is excluded during the electrogalvanizing process, generation of wastewater generated by the use of the above components can be prevented or minimized. Accordingly, the economic efficiency of the electrolytic zinc plating process is not only significantly improved, but also may be environmentally friendly.

In addition, according to the electro-galvanizing method of the present invention, unlike conventional methods, it is possible to perform electro-galvanizing only by a simple process, so that the time for the electro-galvanizing process of steel materials can be significantly reduced. Specifically, in the prior art, the degreasing process using an alkali solution, the derusting and washing process using an acid solution, etc. were separately performed, but according to the present invention, only one time of applying the steel material to the process diluent using the process composition Rust, foreign matter, oil, etc. are removed by the process alone, and according to the present invention, the electro zinc plating process may be simplified. Accordingly, the economic efficiency of the electrolytic zinc plating process can be remarkably improved.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains may easily practice. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. In addition, parts not related to the description are omitted in the drawings to clearly describe the present invention.

The terms or words used in the specification and claims of the present invention are not to be construed as being limited in a conventional or lexical sense, and the inventor can appropriately define the concept of terms to describe his or her invention in the best way. Based on the principles, it should be interpreted as meanings and concepts consistent with the technical spirit of the present invention.

Throughout the specification of the present invention, when a part “includes” a certain component, it means that the component may further include other components, not to exclude other components, unless otherwise stated. .

In the entire specification of the present invention, "washing" may mean "removing rust, foreign substances, oil, and the like on the surface of a steel material." Specifically, removing the rust means "de-rusting", and removing the oil may mean "degreasing."

In the entire specification of the present invention, "A and/or B" means A or B, or A and B.

Hereinafter, the present invention has been specifically described, but the present invention is not limited thereto.

The present invention provides a method for electro galvanizing a steel material.

In one embodiment of the present invention, the bath step of immersing the steel material to be plated in water of 60 ~ 80 ℃; Washing step of immersing the steel material in the composition for the process, followed by ultrasonic treatment; A neutralization step of washing the steel material at least once or more and then neutralizing the steel material by immersing it in an alkali solution; And a plating step of performing electro zinc plating on the neutralized steel material, wherein the composition for the process is linear alkylbenzene sulfonic acid, complex organic-inorganic acid, ammonium chloride, sodium chloride (Sodium Chloride), C9-11 alcohol ethoxylate (Alcohols, C9-11, ethoxylated) and a process composition comprising water; a dilution diluted with water; provides an electrolytic zinc plating method of steel.

According to this embodiment, as the use of sulfuric acid and hydrochloric acid is excluded during the electro-galvanizing process, hydrogen embrittlement generated in the steel material after electro-galvanizing can be prevented. In particular, hydrochloric acid is a major component that generates hydrogen embrittlement of steel materials, but according to this embodiment, the use of hydrochloric acid can be excluded, so that hydrogen embrittlement that occurred in steel materials after electrogalvanization can be prevented. That is, according to this embodiment, even after electrolytic zinc plating, the strength, durability, impact resistance, etc. of the steel material itself can be maintained.

According to this embodiment, hydrogen embrittlement of the steel material is prevented, and at the same time, adhesion between the steel material and the electrolytic zinc plating layer may be excellent. That is, by using the composition for a process according to the present embodiment, an excellent level of electrolytic zinc plating may be possible without following a conventional process using hydrochloric acid, nitric acid, sulfuric acid, or the like.

According to this embodiment, as the use of sulfuric acid, hydrochloric acid, nitric acid, etc. is excluded during the electrogalvanization process, generation of wastewater generated by the use of the above components can be prevented or minimized. In addition, in the prior art, an alkali solution was used for degreasing in addition to the neutralization process, but in this embodiment, degreasing using an alkali solution is not carried out, so generation of wastewater by the alkali solution can also be minimized.

According to the present embodiment, it is possible to omit the wastewater treatment process, and as the process time such as degreasing, acid treatment, and neutralization treatment is significantly shortened, it is possible to perform electrolytic zinc plating using only a simple process unlike the conventional one, thereby significantly improving economic efficiency. Can be.

(1) a bath step of immersing the steel material to be plated in water at 60 to 80°C;

In the bathing step of this embodiment, the steel material to be plated is immersed in hot water at 60 to 80°C. Specifically, the hot water washing step of the present embodiment may be performed by repeating the process of immersing and extracting the steel material to be plated in high temperature water of 60 to 80° C. for multiple times. In the step of washing, the foreign material and oil on the surface of the steel material to be plated may be removed to wash the steel material. In addition, in this embodiment, prior to performing the following washing step, by first performing the bath washing step to remove foreign substances and oil on the surface of the steel material, to extend the service life of the process composition used in the washing step Can.

The temperature of the water in the bath step of this embodiment may be 60 ~ 80 ℃, specifically 65 ~ 75 ℃, more specifically 70 ℃, but is not limited thereto.

If the temperature of the water is less than 60°C in the hot water washing step of the present embodiment, the washing effect may be significantly lower than when the water temperature is 60 to 80°C. On the other hand, when the temperature of the water in the hot water washing step of this embodiment is more than 80 ℃, when the temperature of the water is 60 ~ 80 ℃, there is no difference in washing effect, economic efficiency may be lowered.

Meanwhile, the steel material refers to a combination of iron and steel, and the steel means an alloy of pure iron and carbon. As the steel material, any known material or product that can be electro-galvanized can be applied.

The steel material may be a steel plate for water supply, a conduit steel pipe, a steel plate for piping, a structural steel plate, or a steel plate scaffolding; Thin plates, including zinc iron plate; Wires including wires, steel wires, wire ropes, stranded wires, stranded wires, wire meshes, barbed wires, gabions, sheaths, cores for stranded aluminum strands, and the like; Rolled steel materials including steel sheet, section steel, flat steel, and bar steel; Processed products including pylons, bridges, steel frames, shipbuilding brackets, wire brackets, tanks, etc.; Bolts and nuts including various bolts, nuts, coaters, washers, and the like; Cast iron products including cast iron products, cast steel products, forged steel products, pipe fittings, insulator metal fittings, and the like; And the like, but is not limited thereto.

(2) washing step of immersing the steel material to be plated in the composition for the process, followed by ultrasonic treatment;

In the washing step of this embodiment, the steel material to be plated is immersed in the process composition liquid, and then subjected to ultrasonic treatment. Specifically, in the washing step of this embodiment, the steel material to be plated is completely immersed in the process composition solution, which is a dilution solution diluted with water, so that the steel composition to be plated is subjected to ultrasonic treatment. Can be washed. Rust, dust, foreign substances, oil, etc. on the surface of the steel material to be plated may be removed by the washing. As described above, the removal of rust may mean derusting, and the removal of the oil may mean degreasing.

Process composition is Linear Alkyl Benzene Sulfonic Acid, Complex Organic-Inorganic Acid, Ammonium Chloride, Sodium Chloride, C9-11 Alcohol Ethoxylates (Alcohols, C9-11, ethoxylated) And a process composition comprising water; a diluent diluted with water. Specifically, the composition for the process may include the process composition in an amount of 0.1 to 50 parts by weight with respect to 100 parts by weight of water, but is not limited thereto.

Hereinafter, the composition for the process will be described in detail.

The composition for the process of the present embodiment is Linear Alkyl Benzene Sulfonic Acid, complex organic-inorganic acid, Ammonium Chloride, Sodium Chloride, C9-11 Alcohol Ethoxylate (Alcohols, C9-11) , ethoxylated) and water. Specifically, the process composition of the present embodiment is based on the total weight of linear alkylbenzene sulfonic acid (Linear Alkyl Benzene Sulfonic Acid) 1 to 5% by weight, complex organic-inorganic acid 28 to 35% by weight, ammonium chloride (Ammonium Chloride) 5 to 13 Weight percent, sodium chloride (Sodium Chloride) 1 to 7% by weight, C9-11 alcohol ethoxylate (Alcohols, C9-11, ethoxylated) 1 to 4% by weight and the balance may include water.

As the process composition of this embodiment may have a cleaning performance to remove rust, dust, foreign substances, oil, etc., from the surface of the steel material to be plated, unlike the conventional process in this embodiment, nitric acid, hydrochloric acid, sulfuric acid, etc. Electrolytic zinc plating may be possible without the use of.

In addition, in this embodiment, the rust removal, cleaning, and degreasing effect can be realized by only one step of immersing the steel material in the composition for the process, and the washing step, the acid treatment step, and the degreasing step, respectively, are performed. Rather than the process, the process is simple but the process time can be significantly shortened.

Linear Alkyl Benzene Sulfonic Acid (LABSA) is made from sulfonated linear alkyl benzene, is a yellow or brown liquid, and has excellent biodegradation performance. The linear alkylbenzenesulfonic acid may serve to improve the cleaning performance of the process composition.

Based on the total weight of the composition for the process of the present embodiment, linear alkylbenzenesulfonic acid may be included in 1 to 5% by weight, specifically 1.5 to 4% by weight, and more specifically 2 to 3% by weight.

If, when the composition for the process of the present embodiment comprises less than 1% by weight of linear alkylbenzenesulfonic acid based on the total weight of the composition, the cleaning effect of the steel material is lower than when containing linear alkylbenzenesulfonic acid in 1 to 5% by weight There may be a problem. On the other hand, when the linear composition of the present embodiment contains more than 5% by weight of linear alkylbenzenesulfonic acid based on the total weight of the composition, the cleaning effect of the steel material is lower than when it contains 1 to 5% by weight of linear alkylbenzenesulfonic acid And, there may be a problem that the economic cost is lowered by increasing the process cost.

That is, when the linear alkylbenzenesulfonic acid is not included in 1 to 5% by weight based on the total weight of the process composition of the present embodiment, the cleaning effect of the steel material is reduced, while hydrogen embrittlement of the steel material is prevented while the steel material and It may be difficult to process an electro-galvanized coating having excellent adhesion between the electro-galvanized layers.

The complex organic-inorganic acid may include at least two known organic acids, and at least one known inorganic acid at the same time, but is not particularly limited thereto. The complex organic-inorganic acid may serve to improve the cleaning effect of the process composition.

For example, the complex organic-inorganic acid is formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, acrylic acid acid), Crotonic acid, Oxalic acid, Malonic acid, Succinic acid, Glutaric acid, Cnnamic acid, Glycolic acid , Citric acid and an organic acid comprising two or more selected from the group consisting of levulinic acid; And inorganic acids including at least one selected from the group consisting of phosphoric acid and phosphorous acid.

Specifically, the complex organic-inorganic acid may include citric acid, levulinic acid, and phosphoric acid.

More specifically, the complex organic-inorganic acid may include citric acid, levulinic acid, and phosphoric acid in a weight ratio of 1: 0.1 to 0.5: 3 to 5. In particular, when the complex organic-inorganic acid of the present embodiment contains citric acid, levulinic acid, and phosphoric acid in a weight ratio of 1: 0.1 to 0.5: 3 to 5, the cleaning effect of the steel material is further improved, and hydrogen embrittlement of the steel material is improved. While being prevented, it may be possible to process an electrolytic zinc plating with excellent adhesion between a steel material and an electrogalvanized layer.

The composite organic-inorganic acid based on the total weight of the process composition of the present embodiment may include 28 to 35% by weight, specifically 29 to 33% by weight, and more specifically 30 to 31% by weight.

If, when the composite composition of the present embodiment based on the total weight of the composite organic-inorganic acid less than 28% by weight, compared to the composite organic-inorganic acid containing 28 to 35% by weight, the cleaning effect of the steel material is lowered There may be a problem. On the other hand, when the composite composition of the present embodiment is based on the total weight of the composite organic-inorganic acid based on 35% by weight, the cleaning effect of the steel material is lower than when the composite organic-inorganic acid is included in the 28-35% by weight. There may be a problem, there may be a problem that precipitates or aggregates are formed by side reaction of each component, the solubility of other components in the process composition and the compatibility between each component may be reduced.

That is, when the composite composition of the present embodiment is based on the total weight of the composite organic-inorganic acid is not included in 28 to 35% by weight, the cleaning effect of the steel material is reduced, while hydrogen embrittlement of the steel material is prevented while the steel material and It may be difficult to process an electro-galvanized coating having excellent adhesion between the electro-galvanized layers.

Ammonium Chloride is a salt of ammonia, a pure white, water-soluble crystal in the pure state. The ammonium chloride may serve to improve the cleaning effect of the process composition.

Ammonium chloride may be included in an amount of 5 to 13% by weight, specifically 7 to 10% by weight, and more specifically 8 to 9% by weight based on the total weight of the process composition of the present embodiment.

If, when the composition for the process of this embodiment contains less than 5% by weight of ammonium chloride based on the total weight of the composition, there is a problem that the cleaning effect of the steel material is lowered than when containing ammonium chloride at 5 to 13% by weight Can. On the other hand, when ammonium chloride is included in an amount exceeding 13% by weight based on the total weight of the process composition of the present embodiment, there is a problem in that the cleaning effect of the steel material is lowered than when ammonium chloride is included in 5 to 13% by weight. May be, there may be a problem that the acidity of the process composition is increased.

That is, when the ammonium chloride is not included in 5 to 13% by weight based on the total weight of the process composition of the present embodiment, the cleaning effect of the steel material is reduced, while hydrogen embrittlement of the steel material is prevented while the steel material and electric zinc It may be difficult to process electrolytic zinc plating with excellent adhesion between plating layers.

Sodium chloride (Sodium Chloride) is a compound of sodium and chlorine, and may serve to improve the cleaning effect of the process composition of this embodiment.

Sodium chloride may be included in 1 to 7% by weight, specifically 2 to 6.5% by weight, and more specifically 5 to 6% by weight based on the total weight of the process composition of the present embodiment.

If, when the composition of the present embodiment is based on the total weight of the composition for sodium chloride is less than 1% by weight, than the case of containing 1 to 7% by weight of sodium chloride, there may be a problem that the cleaning effect of the steel material is lowered. . On the other hand, when the sodium chloride is contained in excess of 7% by weight based on the total weight of the process composition of the present embodiment, the rust removal, cleaning effect, and degreasing effect of the steel material are lower than when sodium chloride is included in 1 to 7% by weight. There may be a problem, there may be a problem that the acidity of the process composition is increased.

That is, when sodium chloride is not included in 1 to 7% by weight based on the total weight of the process composition of the present embodiment, the cleaning effect of the steel material is reduced, while hydrogen embrittlement of the steel material is prevented while the steel material and the electrolytic zinc plating layer are prevented. It may be difficult to process an electrolytic zinc plating with excellent adhesion to the liver.

C9-11 alcohol ethoxylate (Alcohols, C9-11, ethoxylated) is a component mainly used as a surfactant, and may serve to improve the cleaning effect of the process composition of this embodiment. Specifically, C9-11 alcohol ethoxylate may serve to remove foreign substances and oil.

C9-11 alcohol ethoxylate based on the total weight of the composition for the process of the present embodiment may include 1 to 4% by weight, specifically 1.5 to 3.5% by weight, and more specifically 2 to 3% by weight.

If, by the total weight of the process composition of the present embodiment, C9-11 alcohol ethoxylate in an amount of less than 1% by weight, than C9-11 alcohol ethoxylate in an amount of 1 to 4% by weight, steel There may be a problem that the cleaning effect of the material is lowered. On the other hand, when the C9-11 alcohol ethoxylate is included in an amount greater than 4% by weight based on the total weight of the process composition of the present embodiment, the steel is more than when the C9-11 alcohol ethoxylate is included in 1-4% by weight. There may be a problem that the washing effect of the material is lowered, and there may be a problem that the storage stability of the process composition is lowered.

That is, when the C9-11 alcohol ethoxylate is not included in 1 to 4% by weight based on the total weight of the process composition of the present embodiment, the cleaning effect of the steel material is reduced, while hydrogen embrittlement of the steel material is prevented. It may be difficult to process an electrolytic zinc plating with excellent adhesion between a steel material and an electrogalvanized layer.

The ultrasonic treatment may be to immerse the steel material to be plated in the composition for the process so as to be completely submerged, and then to perform the ultrasonic treatment for the composition for the process. The steel material to be plated may be washed and degreased simultaneously by the ultrasonic treatment.

The ultrasonic treatment may be performed in a region of 20 kHz to 40 kHz frequency, specifically 25 kHz to 38 kHz frequency, and more specifically 30 kHz to 35 kHz frequency.

If, when the ultrasonic treatment is performed at a frequency of less than 20 kHz, the problem of the rust removal, cleaning effect, and degreasing effect of the steel material is lowered than when the ultrasonic treatment is performed at a frequency of 20 kHz to 40 kHz. It can be. On the other hand, when the ultrasonic treatment is performed at a frequency of more than 40 kHz, there is no difference in effect from the case where the ultrasonic treatment is performed at a frequency of 20 kHz to 40 kHz, which may not be economical.

That is, when the ultrasonic treatment is not performed at a frequency of 20 kHz to 40 kHz in the washing step of the present embodiment, the rust removal, cleaning, and degreasing effect of the steel material is reduced, while hydrogen embrittlement of the steel material is prevented while steel is prevented. It may be difficult to process the electrolytic zinc plating, which has excellent adhesion between the material and the electrogalvanized layer.

The ultrasonic treatment may vary depending on the size, shape, and amount of the process composition, and is not particularly limited. For example, the ultrasonic treatment may be performed for 45 to 80 seconds, specifically 50 to 70 seconds, and more specifically 55 to 60 seconds after immersing the steel material in the composition for the process.

If, when the ultrasonic treatment time is less than 45 seconds, there may be a problem that the rust removal, cleaning effect, degreasing effect of the steel material is lowered than when the ultrasonic treatment is performed for 45 to 80 seconds. On the other hand, when the ultrasonic treatment time is more than 80 seconds, there may be a problem that the rust removal, cleaning effect and degreasing effect of the steel material is lowered than when the ultrasonic treatment is performed for 45 to 80 seconds.

When the ultrasonic treatment is performed in the washing step of the present embodiment, the temperature of the composition liquid for the process is 45 to 52°C, and may be specifically 50°C.

If, when the temperature of the composition composition for the process is less than 45 ℃, there may be a problem that the rust removal, cleaning effect, degreasing effect of the steel material is lower than the temperature of the composition composition for the process is 45 to 52 ℃. On the other hand, when the temperature of the composition for the process is greater than 52°C, there may be a problem that the rust removal, cleaning effect, and degreasing effect of the steel material are lower than when the temperature of the composition for the process is 45 to 52°C. There may be a problem that precipitates or aggregates are formed by side reactions. In addition, evaporation of the liquid component of the process composition liquid may be induced, and there may be a problem that a process composition liquid loss occurs.

According to the above, by using the composition for the process according to the present embodiment, without performing a conventional degreasing process, acid treatment process, washing process, etc., respectively, it is possible to simultaneously implement rust removal, cleaning and degreasing effect in a single process. Can. That is, it may be possible to pre-process the steel material in a short time by a simple process.

(3) a neutralization step of washing the steel material at least once or more and then neutralizing the steel material by immersing it in an alkali solution;

In the neutralization step of this embodiment, after washing the steel material treated in the washing step at least once, the steel material is immersed in an alkali solution to neutralize it. Specifically, in the neutralization step of this embodiment, after the steel material treated in the washing step is washed with water 1 to 2 times, neutralization is performed by immersing the washed steel material so as to be completely immersed in an alkali solution. Can.

The alkali solution may be a raw material containing a hydroxyl group such as ammonium hydroxide, sodium hydroxide, or calcium hydroxide, or a solution containing a raw material generating a hydroxyl group such as quicklime or magnesia, but is not limited thereto.

Specifically, the alkali solution may be a solution containing sodium hydroxide and water.

More specifically, the alkali solution may be a 1-5% aqueous sodium hydroxide solution, but is not limited thereto.

(4) plating step of performing electro zinc plating on the neutralized steel material;

In the plating step of the present embodiment, electrolytic zinc plating may be performed on the steel material neutralized in the neutralization step according to a known method. Specifically, in the plating step of the present embodiment, 12 to 20 g/L of zinc oxide, 10 to 30 g/L of leveling agent to 120 to 150 g/L of sodium hydroxide, 2 to 10 mL/L of brightener, and nonionic surfactant 0.1 Electrolytic zinc plating can be carried out using an alkaline plating solution containing ∼1 mL/L at a temperature of 20 to 40° C. and a current density of 1 to 5 A/dm ² .

After the plating step, an activation step of immersing the electro-galvanized steel material in the composition composition for the process to activate it may be further performed. Specifically, in the activating step, the electrolytic galvanized steel material is completely immersed in the composition composition for the process having the same composition as the washing step, and immersed for 5 to 20 seconds.

Generally, a solution containing nitric acid is mainly used for activating an electrogalvanized steel material, but in the case of the present embodiment, the solution containing nitric acid is substituted for the solution containing nitric acid, nitric acid and sulfuric acid. Activation can be performed with a process composition liquid using a process composition. That is, as the use of nitric acid can be excluded and wastewater generation is reduced, it may be environmentally friendly.

If, when the activation step is performed in less than 5 seconds, the surface activation and etching effects are not sufficient than when the activation step is performed for 5 to 20 seconds, and even if a chromate treatment and a phosphate treatment process are additionally performed, the film is coated. (Tissue) may not be well formed. On the other hand, when the activation step is performed for more than 20 seconds, there may be a problem that an electrolytic zinc plating layer is damaged or a by-product is formed on the surface.

After the activating step, a normal post-treatment process of electrolytic zinc plating may be performed. The conventional post-treatment process may include, but is not limited to, chromate treatment, inorganic coating treatment, phosphate treatment, fingerprint treatment, surface gloss treatment, other resin coating treatment, and the like.

Hereinafter, a method for electro zinc plating of a steel material of the present invention will be described in detail through Examples, Comparative Examples, and Experimental Examples. Since these examples are only for illustrating the present invention, it should not be construed that the scope of the present invention is limited by these examples.

[Example]

Examples 1 to 4

Each component was mixed with a composition according to Table 1 [unit: wt%] to prepare a process composition. Thereafter, the process composition was mixed and diluted to 20 parts by weight with respect to 100 parts by weight of water to prepare a process composition liquid.

At this time, in Table 1, as the composite organic-inorganic acid, citric acid, levulinic acid, and phosphoric acid were mixed in a mixing ratio of Table 2 [unit: weight ratio].

Example 1 Example 2 Example 3 Example 4 Linear alkylbenzenesulfonic acid 3 4 4 4 Complex organic-inorganic acid 30 28 28 28 Ammonium chloride 9 12 12 12 Sodium chloride 6 3 3 3 C9-11 alcohol ethoxylate 3 4 4 4 water to.100

Example 1 Example 2 Example 3 Example 4 Citric acid One One One One Levulinic acid 0.3 0.3 0.1 0.5 Phosphoric acid 4 4 4 4

Using the composition liquid for the above-described process, the following electro-galvanizing process was performed.

(1) First, a high-strength bolt (10.9) was prepared as a steel material to be plated. The high-strength bolt was immersed in hot water at 70°C.

(2) The high-strength bolt is taken out from hot water, and the high-strength bolt is immersed in the process composition liquid according to Example 1 to be completely immersed, and then ultrasonicated at a frequency of about 30 kHz for about 60 seconds to wash. It was carried out. At this time, the temperature of the composition liquid for the process was about 50°C.

Thereafter, the high-strength bolt was washed twice with water. At this time, the water washing means the process of washing the high-strength bolt for about 10 to 15 seconds with running water.

(3) The high-strength bolt was neutralized by immersing the high-strength bolt washed and degreased according to the above for about 10 seconds to be completely immersed in a 5% aqueous sodium hydroxide solution.

(4) Subsequently, the neutralized high-strength bolt was electrogalvanized. The electrolytic zinc plating is performed using an alkaline plating solution containing 12 g/L zinc oxide, 140 g/L sodium hydroxide, 20 g/L leveling agent, 5 mL/L brightener, and 0.5 mL/L nonionic surfactant. , Temperature 20-40°C and operating current density 1-5 A/dm ² . At this time, the alkaline plating solution was used in accordance with the size of the high-strength bolt and scaled up while maintaining the proportion of the components.

(5) The high-strength bolt electroplated according to the above was completely immersed in the composition for the process according to Example 1, and immersed for about 5 seconds to activate the electro-galvanized layer.

Thereafter, according to the above, the electro-galvanizing treatment was completed by washing the electro-galvanized high-strength bolt 1 to 2 times.

In addition, electrolytic zinc plating was performed using the process composition of Example 2 under the same method and conditions as that of electrolytic zinc plating using the process composition of Example 1, and the process of Example 3 was performed. Electro-galvanization was performed using the composition, and electro-galvanization was performed using the process composition of Example 4.

[Comparative Example]

Comparative Examples 1 to 10

A process composition was prepared in the same manner as in Example 3, except that the composition in Table 3 [unit: wt%] was followed, and electrolytic zinc plating treatment was performed on the high-strength bolt using the same.

ratio
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One ratio
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2 ratio
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3 ratio
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4 ratio
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5 ratio
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6 ratio
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7 ratio
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8 ratio
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9 ratio
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10 Linear alkylbenzenesulfonic acid 0.5 10 4 4 4 4 4 4 4 4 Complex organic-inorganic acid 28 28 23 40 28 28 28 28 28 28 Ammonium chloride 12 12 12 12 One 18 12 12 12 12 Sodium chloride 3 3 3 3 3 3 0.5 12 3 3 C9-11 alcohol ethoxylate 4 4 4 4 4 4 4 4 0.5 10 water to.100

Comparative Examples 11 to 12

Electrolytic zinc plating was performed in the same manner as in Example 3, except that the temperature of the composition liquid for the process of the washing step was Table 4 [unit: ℃].

Example 3 Comparative Example 11 Comparative Example 12 Process composition temperature (℃) 50 40 57

Comparative Examples 13 to 14

In the washing step, after immersing the high-strength bolt in the composition for the process, electrolytic zinc plating was performed in the same manner as in Example 3, except that the ultrasonic treatment time was Table 5 [unit: second].

Example 3 Comparative Example 13 Comparative Example 14 Sonication time (sec) 60 40 90

Comparative Example 15

Electro zinc plating was performed in the same manner as in Example 3, except that the ultrasonic treatment was performed at 15 kHz.

Comparative Example 16

Electrolytic zinc plating was performed using hydrochloric acid as in the prior art, and specifically as follows.

5% by weight of sulfuric acid, 10% by weight of hydrochloric acid, 10% by weight of surfactant, and 75% by weight of water were degreased by immersing the high-strength bolt in an acid solution for 15 to 20 minutes, and then the high-strength bolt was dissolved in 10% silicic acid. After soaking in an aqueous sodium solution for 15 to 20 minutes to neutralize the acid component remaining in cast iron, the cast iron was washed again with water and immersed in a 5% sulfuric acid solution for 15 minutes to wash.

Subsequently, the high-strength bolts washed according to the above were electro-galvanized under the same conditions as in Example 3, thereby completing the electro-galvanizing treatment of the high-strength bolts according to the conventional method.

Comparative Example 17

It was prepared in the same manner as in Example 3, except that the (1) washing step was not performed.

[Experimental Example]

Experimental Example 1: Evaluation of adhesion

According to the CROSS-CUT test method (ASTM D 3359 test standard), the adhesion of the electrogalvanized layer formed according to Example 1 was evaluated 10 times, and the average value is shown in Table 6.

On the other hand, in order to facilitate the CROSS-CUT test, the process composition liquid of Example 1 (a dilution of the process composition) was used, and electrolytic zinc plating was performed in the same manner as in Example 1, but steel was used instead of high-strength bolts. After electro zinc plating was performed on the steel plate of the material, adhesion was evaluated.

The adhesion was evaluated as OB to 5B, as described below, and the average value of repeating the same experiment 10 times is shown in Table 8. At this time, it means that the closer to 5B, the better the adhesion.

According to the same conditions as in Example 1, the adhesion properties of Examples 2 to 4 and Comparative Examples 1 to 17 were evaluated, and the results are shown in Table 6.

Adhesion Adhesion Example 1 4.5B Comparative Example 1 2.0B Example 2 4.3B Comparative Example 2 2.0B Example 3 4.0B Comparative Example 3 2.0B Example 4 4.0B Comparative Example 4 2.0B Comparative Example 5 2.0B Comparative Example 6 2.0B Comparative Example 7 2.0B Comparative Example 8 2.0B Comparative Example 9 2.0B Comparative Example 10 2.0B Comparative Example 11 3.0B Comparative Example 12 3.0B Comparative Example 13 3.0B Comparative Example 14 3.0B Comparative Example 15 3.0B Comparative Example 16 4.0B Comparative Example 17 2.0B

Looking at Table 6, according to this embodiment, it can be seen that the adhesion between the steel material and the electro-galvanized layer is excellent.

That is, according to the present embodiment, it means that the rust, foreign matter, and oil of the steel material to be plated are sufficiently removed before the electrogalvanization, so that the steel material and the electrogalvanized layer can be sufficiently adhered.

Experimental Example 2: Evaluation of hydrogen embrittlement

The tensile strength of the high-strength bolts (10.9) electroplated according to Examples 1 to 4 and Comparative Example 16 (using hydrochloric acid) was measured to determine whether hydrogen embrittlement occurred.

After measuring the tensile strength 5 times, the average value is shown in Table 7 [unit: N/mm ² ]. At this time, before the electro-galvanizing, the tensile strength of the high-strength bolt (10.9) itself was 1,040 N/mm ² [according to the ISO 898-1 standard].

At this time, the tensile strength was carried out according to the test method KS B 0802: 2003.

After electro zinc plating,
High tensile bolt tensile strength After electro zinc plating,
High tensile bolt tensile strength Example 1 1,000 ± 20 Comparative Example 16 790 Example 2 Example 3 Example 4

Looking at Table 7, unlike Examples 1 to 4 according to the present Example, in Comparative Example 16 using hydrochloric acid as in the prior art, not according to the present Example, after performing electro zinc plating, the tensile strength is significantly lowered. Able to know. That is, according to the present embodiment, it can be seen that even when electrolytic zinc plating is performed, the tensile strength of the steel material is almost maintained, and thus hydrogen embrittlement is prevented.

In summary, according to the present invention, according to the present invention, unlike conventional, the use of hydrochloric acid, nitric acid, sulfuric acid, etc. is excluded, and even without hydrogen embrittlement, electro zinc plating excellent in adhesion can be carried out in a short time by a simple process. In addition, as the use of hydrochloric acid, nitric acid, sulfuric acid, and the like is excluded, generation of wastewater due to the treatment of the components is prevented, and cost and time associated with wastewater treatment can be reduced, thereby improving economic efficiency.

As described above, the description of the present invention is for illustration only, and those having ordinary skill in the art to which the present invention pertains can easily be modified into other specific forms without changing the technical spirit or essential features of the present invention. You will understand. Therefore, it should be understood that the above-described embodiments are illustrative in all respects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is indicated by the following claims rather than the above detailed description, and it should be interpreted that all changes or modified forms derived from the meaning and scope of the claims and equivalent concepts thereof are included in the scope of the present invention. do.

Claims (7)

A bath step of immersing the steel material to be plated in water at 60 to 80°C;
Washing step of immersing the steel material in the composition for the process, followed by ultrasonic treatment;
A neutralization step of washing the steel material at least once or more and then neutralizing the steel material by immersing it in an alkali solution; And
Including the plating step of conducting electro-galvanizing the neutralized steel material;
The composition for the process is
Contains Linear Alkyl Benzene Sulfonic Acid, Complex Organic-Inorganic Acid, Ammonium Chloride, Sodium Chloride, C9-11 Alcohol Ethoxylate (Alcohols, C9-11, ethoxylated) and Water Process composition to be; is a diluent diluted in water;
The composition for the process
Based on the total weight of the composition for the process, Linear Alkyl Benzene Sulfonic Acid 1-5 wt%, Complex Organic-Inorganic Acid 28-35 wt%, Ammonium Chloride 5-13 wt%, Sodium Chloride Chloride) 1 to 7% by weight, C9-11 alcohol ethoxylate (Alcohols, C9-11, ethoxylated) 1 to 4% by weight, and characterized in that it contains a residual amount of water, steel material using an environmentally friendly process composition Zinc plating method to prevent hydrogen embrittlement.
According to claim 1,
In the washing step,
The temperature of the composition liquid for the process is 45 ~ 52 ℃,
After immersing the steel material in the composition for the process, characterized in that the ultrasonic treatment for 45 to 80 seconds, using an environment-friendly process composition to prevent hydrogen embrittlement of the steel material electro zinc plating method.
delete According to claim 1,
The complex organic-inorganic acid
Formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, acrylic acid, and crotonic acid , Oxalic acid, Malonic acid, Succinic acid, Glutaric acid, Cnnamic acid, Glycolic acid, Citric acid and levulin Organic acids containing two or more selected from the group consisting of acids (Levulinic acid); And
Inorganic acid containing at least one selected from the group consisting of phosphoric acid (Phosphoric acid) and phosphorous acid (Phosphorous acid); characterized in that it comprises, an electrolytic zinc plating to prevent hydrogen embrittlement of steel materials using an environmentally friendly process composition Way.
The method of claim 4,
The complex organic-inorganic acid
The citric acid, the levulinic acid and the phosphoric acid is characterized in that it comprises a weight ratio of 1: 0.1 ~ 0.5: 3 ~ 5, the electro zinc plating method to prevent hydrogen embrittlement of steel materials using an environment-friendly process composition.
According to claim 1,
After the plating step,
An activation step of immersing and activating the electro-galvanized steel material in the composition for the process, further comprising an electro-zinc plating method for preventing hydrogen embrittlement of the steel material using an environment-friendly process composition.
The method of claim 6,
In the activation step
The electro-galvanizing method for preventing hydrogen embrittlement of steel materials using an eco-friendly process composition, characterized in that the electro-galvanized steel material is immersed in the process composition solution for 5 to 20 seconds.