KR20010048741A - A Zn-Ni ALLOY ELECTRODEPOSITION SOLUTION AND A METHOD FOR MANUFACTURING Zn-Ni ALLOY ELECTRODEPOSITION STEEL SHEET BY USING IT - Google Patents

Abstract

PURPOSE: A Zn-Ni alloy electroplating solution and a method for manufacturing Zn-Ni alloy electroplating steel sheet using the same are provided which can manufacture a Zn-Ni alloy electroplating steel sheet having superior appearance of the surface and cohesion by using a basic solution in which zinc chloride and nickel chloride are used as a basic materials and chloride ions are adjusted by potassium chloride, and adding ammonium chloride and an appropriate amount of a mixed additive of sodium salt condensed naphthalene sulfonic acid and sodium sulfate as an additive. CONSTITUTION: The Zn-Ni alloy electroplating solution is prepared by adding 0.1 to 1.0 mols of ammonium chloride, 1:0.001-0.008 mol ratio of sodium sulfonate for the ammonium chloride, and 1:0.1 - 0.5 mol ratio of sodium sulphate for the sodium sulfonate to a chloride based Zn-Ni alloy electroplating solution comprising 0.5 to 2.0 mols of zinc ions, 0.1 to 0.5 mols of nickel ions and 6.0 to 9.0 mols of chloride ions. In a method for electroplating Zn-Ni on a substrate metal, the method for manufacturing Zn-Ni alloy electroplating steel sheet comprises the process of electroplating the substrate metal using the Zn-Ni alloy electroplating solution under the plating conditions of pH of the plating solution of 2.5 to 4.5, a temperature of the plating solution of 55 to 70 deg.C, a current density of 40 to 180 A/dm2, and a relative flow rate of the plating solution and an anode of 0.5 to 2.5 m/sec.

Description

Zn-Ni ALLOY ELECTRODEPOSITION SOLUTION AND A METHOD FOR MANUFACTURING Zn-Ni ALLOY ELECTRODEPOSITION STEEL SHEET BY USING IT}

The present invention relates to a zinc-nickel alloy electroplating solution using a soluble anode, and more particularly, to a zinc-nickel alloy electroplating solution capable of obtaining good surface appearance and adhesion by adjusting the composition and plating composition of the plating solution. It relates to a method of manufacturing a zinc-nickel alloy electroplated steel sheet using the same.

Since ancient times, metal plating on iron has been widely used for rust prevention and decoration. In particular, zinc electroplating has been developed to secure the corrosion resistance of the steel sheet has been widely used in the fields of home appliances, automobiles, construction and the like. However, in order to secure corrosion resistance under severe atmosphere, the thickness of the galvanized layer must be increased, which has an adverse effect on adhesion and workability as well as an increase in cost. Therefore, zinc-nickel alloy electroplating has been developed to solve this drawback.

There are various zinc-nickel alloy electroplating methods depending on the components of the bath. Among them, an acidic bath-based plating material production method is widely used. Acid baths include sulfide baths as the basis and chloride baths as the base. Chloride baths have better electrical conductivity than sulfide baths, which enables high current density plating and mainly use soluble anodes, making solution control easier and less expensive than sulfide baths using insoluble anodes. The use of the soluble anode mainly includes zinc and nickel, and zinc is generally about 85 or more. Therefore, sludge or foreign matter should not remain on the zinc anode, so that it can have a uniform solubility and can produce a good plating product. However, since zinc and nickel have a large potential difference in the chloride plating bath, sludge in the zinc hydroxide system is generated in the zinc anode due to the electroless substitution of nickel in the zinc anode. This sludge adheres to the surface of the anode, so that zinc dissolution becomes uneven during continuous operation, causing severe concentration change of the plating solution, preventing the conduction, increasing the plating voltage, and making the surface appearance of the plating layer uneven. In particular, the sludge adhering to the surface of the anode is peeled again in the form of sludge, causing streaks and burning stains on both edges of the steel sheet in the plating layer. Furthermore, the adhesion of the plating layer is also degraded due to the sludge mixing.

Conventional techniques for solving such problems include Japanese Patent Application Laid-Open No. 58-55585, Japanese Patent Application Laid-Open No. 59-211589, and Korean Patent Application No. 93-29962.

Japanese Patent Application Laid-Open No. 58-55585 relates to improving the surface appearance of a plating layer by adding one or two or more kinds of chlorides to a plating solution containing zinc chloride and nickel chloride as a main component, or the adhesion of the plating layer. There is a problem with this falling.

Japanese Patent Application Laid-Open No. 59-211589 discloses a yellowish brown or blue-violet oxide incidentally to the precipitate by adding some ammonium chloride salt to a plating solution containing zinc chloride and nickel chloride as a main component, and a plating solution containing lactate and changing plating conditions. This technique effectively suppresses the mixed precipitation of However, according to the above method, the precipitation of oxide is suppressed up to about 100 hours at the beginning, but there is a drawback that the precipitate appears again during further operation.

Korean Patent Application No. 93-29962 is a method of improving the solubility of the positive electrode by adding alcohol as an additive, but has a disadvantage in that the alcohol is volatilized and consumed severely when used for a long time.

In addition, although ammonium chloride salt is added to the plating solution to improve the reactivity of the positive electrode, this also has a problem of increasing the amount of sludge in the solution by accelerating the release of sludge to the positive electrode.

As described above, the conventional techniques proposed up to now try to improve the surface appearance of the coating layer and the adhesion of the coating layer by improving the solubility of the anode in zinc-nickel alloy plating, but the sludge increases again or changes the plating property of the solution after prolonged use. Rather, there was a defect that the surface appearance of the plating layer is poor.

MEANS TO SOLVE THE PROBLEM The present inventors carried out research and experiment in order to solve the above-mentioned problems of the prior art, and proposed the present invention based on the results. Zinc-nickel alloy electroplating sheet with excellent surface appearance and adhesion by using a basic solution and adding an appropriate amount of a mixed additive of ammonium chloride salt and sodium salt condensed naphthalene sulfonic acid and sodium sulfate as an additive. To provide a zinc-nickel electroplating solution that can be prepared and a zinc-nickel alloy electroplating steel sheet having excellent surface appearance and adhesion using the same, and its purpose is to provide.

The present invention is a chloride-based zinc-nickel alloy electroplating solution composed of zinc ion: 0.5 to 2.0 mol, nickel ion: 0.1 to 0.5 mol, chloride ion: 6.0 to 9.0 mol,

(a) 0.1-1.0 molar ammonium chloride salt;

(b) from 1: 0.001 to 0.008 molar ratio of sodium sulfonate relative to the ammonium chloride salt; And

(c) A zinc-nickel alloy electroplating solution formed by adding 1: 0.1 to 0.5 molar ratio of sodium sulfate to sodium sulfonate.

In addition, the present invention is a method of electroplating zinc-nickel on a base metal,

Using the plating solution, the pH of the plating solution was 2.5 to 4.5, the temperature was 55 to 70 ° C, the current density was 40 to 180 A / dm 2, and the relative flow rates of the plating solution and the cathode were 0.5 to 2.5 m. The present invention relates to a method of manufacturing a zinc-nickel alloy electroplated steel sheet by electroplating under a plating condition of / sec.

Hereinafter, the present invention will be described in detail.

[Zinc-Nickel Electroplating Solution]

The present invention provides a zinc-nickel alloy electroplating solution by adding an appropriate amount of sodium sulfonate and sodium sulfate to a plating solution mainly composed of zinc chloride, nickel chloride and ammonium chloride salts, thereby forming the surface appearance and adhesion of the zinc-nickel alloy electroplating steel sheet. There is a feature to improve this.

In the plating solution of the present invention, when the zinc ion molar concentration is less than 0.5 moles, metal ions may be insufficient to burn tanned steel sheets, and when the molar concentration exceeds 2.0 moles, the plating layer may be powder-plated. This becomes inferior to adhesiveness. Therefore, the zinc ion is preferably limited to 0.5 to 2.0 moles.

If the nickel ion molar concentration of the plating solution is less than 0.1 mole, the nickel content in the alloy of the plating layer is not secured because the nickel content is not more than 10, the corrosion resistance is lowered. And poor corrosion resistance. Therefore, the nickel ion is preferably limited to 0.1 ~ 0.5 mol.

When the molar concentration of chloride ion of the plating solution is less than 6.0 moles, a large amount of burning occurs due to a decrease in electrical conductivity, and when it exceeds 9.0 moles, chloride ions are precipitated due to solubility problems. Therefore, the chloride ion is preferably limited to 6.0 ~ 9.0 mol.

On the other hand, when the molar concentration of the ammonium chloride salt of the plating solution is less than 0.1 mol, a large amount of sludge is generated, which makes it difficult to perform continuous plating operation, and when it exceeds 1.0 mol, a black film is generated at the anode and the plating solution is formed. Is contaminated. Therefore, the ammonium chloride is preferably limited to 0.1 ~ 1.0 mole.

The concentration of sodium sulfonate is preferably 1: 0.001 to 0.008 molar ratio with respect to the ammonium chloride salt, because when the molar ratio of ammonium chloride is less than 0.001, the surface appearance and adhesion of the plating layer may not be suppressed due to the sludge of the anode coating during operation. This is because, when it is not improved and exceeds 0.008, the current efficiency of the plating layer is lowered, and burnable surface defects are generated at the edges. Therefore, the sodium sulfonate is preferably limited to 1: 0.001 to 0.008 molar ratio with respect to the ammonium chloride.

In addition, the sodium sulfate is preferably 1: 0.1 to 0.5 molar ratio with respect to sodium sulfonate, the reason is that when the ratio of sodium sulfate to sodium sulfonate is less than 0.1, the surface appearance is yellow, and if it exceeds 0.5, the adhesion decreases Because it becomes. Therefore, the sodium sulfate is preferably limited to 1: 0.1 to 0.5 molar ratio with respect to the sodium sulfonate.

[Manufacturing method of zinc-nickel alloy electroplating steel sheet]

The present invention relates to a method for producing a zinc-nickel alloy electroplated steel sheet by electroplating the zinc-nickel alloy electroplating solution of the present invention on a steel sheet. In the case of electroplating according to the present invention, the plating conditions are pH: 2.5 to 4.5 of the plating solution, temperature: 55 to 70 ° C, current density: 40 to 180 A / dm 2, and the relative flow rates of the plating solution and the cathode are 0.5 to 2.5. It is preferable to set it as m / sec.

If the pH of the plating solution is less than 2.5, the plating surface becomes dark and semi-gloss, and if it exceeds 4.5, the plating solution is contaminated by sludge of impurity ions dissolved in the solution, so the pH is preferably limited to 2.5 to 4.5.

When the temperature of the plating solution is less than 55 ° C., the color of the plating layer is dark and the adhesion of the plating layer is inferior, resulting in peeling. On the other hand, when the temperature of the plating layer exceeds 70 ℃ plating phenomena are severe and the gloss of the plating layer is lost. Therefore, the temperature of the plating solution is preferably limited to 55 ~ 70 ℃.

It is preferable to limit the current density to 40 ~ 180A / dm 2, which is when the current density is less than 40A / dm 2, the plating crystals are coarse and the adhesion is poor, if the current density exceeds 180A / dm 2 a large amount of edge burning occurs Because it becomes.

The relative flow rate of the plating liquid and the negative electrode (steel plate of the plated body) is preferably limited to 0.5 to 2.5 m / sec. When the relative flow rate is less than 0.5 m / sec, a large amount of edge burning occurs and 2.5 m / sec. It is because plating operation becomes difficult when it exceeds.

Hereinafter, the present invention will be described in more detail with reference to Examples.

(Example)

After the plating of the solution having the plating liquid composition shown in Table 1 as a base metal for 5 days (120 hours) using a cold rolled steel sheet as a base metal, the turbidity, surface appearance and plating adhesion were measured, and the evaluation results are shown in Table 1 below. Shown in The turbidity of Table 1 is measured by the amount of turbidity generated in the plating solution after 4 hours of continuous electroplating of the solution as a positive electrode reactivity test apparatus. The plating adhesion is measured by the peeling amount of the plating layer buried in the tape after bending 120 °, it was shown as defective when the peeled plating layer is visible on the tape. In addition, the surface appearance was evaluated by the degree of gloss and whiteness of the product plated with a plating amount of 30g / ㎡, the glossiness measured by the glossiness is more than 70 is good, the less is shown as poor, the whiteness measured by the color difference meter 60 or more was good and the following was shown to be bad.

division Plating solution Additive condition Zn ²⁺ Ni ²⁺ Cl ^- NH ⁴⁺ NH ⁴⁺ : Sodium sulfonate (molar ratio) Sodium sulfonate: Sodium sulfate (molar ratio) Plating solution turbidity (NTU) Glossiness Whiteness Peeling Comparative Example 1 1.1 0.18 7.0 0.8 1: 0.00 0: 0 0.9 Bad Bad Bad Comparative Example 2 1: 0.0005 1: 0.3 0.7 Bad Bad Bad Inventive Example 3 1: 0.001 0.2 Good Good Good Inventive Example 4 1: 0.005 0.1 Good Good Good Inventive Example 5 1: 0.008 0.2 Good Good Good Comparative Example 6 1: 0.01 0.2 Bad Bad Good Comparative Example 7 1: 0.005 1: 0.00 0.3 Bad Bad Good Comparative Example 8 1: 0.05 0.3 Bad Bad Good Inventive Example 9 1: 0.1 0.2 Good Good Good Inventive Example 10 1: 0.3 0.1 Good Good Good Inventive Example 11 1: 0.5 0.2 Good Good Good Comparative Example 12 1: 0.6 0.3 Good Bad Bad

As shown in Table 1, all of the invention examples in accordance with the present invention exhibits a low turbidity amount of 0.2 or less, and also shows good glossiness and whiteness, indicating that the surface appearance is good. Moreover, it turns out that plating peelability is also favorable and it is excellent also in adhesiveness. On the other hand, Comparative Examples (1) and (2), in which no sodium sulfonate was added or traced, were poor in all evaluations, and Comparative Example (6) in which an excess amount was added and Comparative Example in which no sodium sulfate was added or traced was added. Although (7) and (8) had good plating peeling property, it is inferred that the surface appearance was bad because of poor gloss and whiteness. In addition, in the case of Comparative Example (12) in which sodium sulfate was excessively added than the present invention, the whiteness and the peeling property were poor.

As described above, the present invention has an effect of obtaining a plated steel sheet having excellent quality with good surface appearance and adhesion by appropriately adjusting the composition and plating conditions of the chloride plating solution.

Claims (2)

In a chloride-based zinc-nickel alloy electroplating solution composed of zinc ion: 0.5 to 2.0 mol, nickel ion: 0.1 to 0.5 mol, chloride ion: 6.0 to 9.0 mol, (a) 0.1-1.0 molar ammonium chloride salt; (b) from 1: 0.001 to 0.008 molar ratio of sodium sulfonate relative to the ammonium chloride salt; And (c) A zinc-nickel alloy electroplating solution formed by adding 1: 0.1 to 0.5 molar ratio of sodium sulfate to sodium sulfonate. In the method of electroplating zinc-nickel on a base metal, Using the zinc-nickel alloy electroplating solution of claim 1, the pH of the plating solution is 2.5 to 4.5, the temperature is 55 to 70 ° C, the current density is 40 to 180 A / dm 2, and the plating solution and the cathode A method of manufacturing a zinc-nickel alloy electroplated steel sheet characterized by electroplating under plating conditions with a relative flow rate of 0.5 to 2.5 m / sec.