KR20090065021A - Chloride zn-ni alloy electrodeposition electrolyte with excellent surface appearance and preparing method of zn-ni alloy electrodeposited steel sheet using the same - Google Patents

Abstract

Chloride Zn-Ni alloy electrodeposition electrolyte with excellent surface appearance and a manufacturing method of Zn-Ni alloy electrodeposited steel sheet using the same are provided to minimize the generation of hydrogen by using a plating solution composed mainly of zinc chloride, nickel chloride, and KCL. Chloride Zn-Ni alloy electrodeposition electrolyte with excellent surface appearance contains a mixture of nickel chloride compound and zinc chloride compound in which total density of nickel and zinc is 150-200g/L, chloride in which chlorine density is 300-350g/L as electrolyte, and an additive solution 0.1-2.0ml/L. The additive solution is produced by mixing an additive including sodium benzoate, saccharin, uric acid, and sodium sulfonate with water at the mass ratio of 1:1.5~3.

Description

CHLORIDE Zn-Ni ALLOY ELECTRODEPOSITION ELECTROLYTE WITH EXCELLENT SURFACE APPEARANCE AND PREPARING METHOD OF Zn-Ni ALLOY ELECTRODEPOSITED STEEL SHEET USING THE SAME}

The present invention is to form a uniform electrodeposition layer while suppressing the sludge of the zinc anode generated during the electrolytic plating of the chloride bath zinc-nickel alloy using a soluble anode, the plating solution to ensure good corrosion resistance, surface appearance and adhesion and It relates to a plated steel sheet used.

Electroplating metal plating has long been used for rust prevention, decoration, and the like. Electro galvanization has been developed to secure corrosion resistance of double steel sheets and has been widely used in fields such as home appliances, automobiles, and construction.

However, since this is intended to improve the corrosion resistance by the sacrificial method of zinc, it is necessary to increase the thickness of the zinc plated layer in a harsh atmosphere. In this case, the increase in cost and poor adhesion and processability.

Therefore, zinc-nickel alloy electroplating has been developed to solve this drawback. Zinc-nickel alloy electroplating has a number of components depending on the composition of the plating bath, of which the plating material production method based on the acid bath is generally 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 are more convenient and less expensive to control solutions than sulfide baths that use insoluble anodes, mainly using soluble anodes.

Soluble anodes are predominantly zinc and nickel, with zinc in excess of about 80%. However, in the chloride bath in which soluble zinc is used, the surface quality of the plated product is poor due to sludge, foreign matter, etc., which are inevitably generated by zinc and nickel on the surface of the anode during plating. In addition, after the steel plate is plated in the plating cell of the continuous electroplating apparatus, sludge or foreign substances present in the plating solution move through the steel plate to the surface of the conversion roll which rolls and changes the direction, and grows by electroless substitution.

Due to this phenomenon, the plating material has a flaw on the surface, and if severe, the operation must be stopped and the roll should be cleaned. Due to the potential difference between zinc and nickel, a large amount of hydrogen, which is a side reaction at high current, is generated, resulting in a decrease in current efficiency.

In order to solve such a defect, conventionally attempted to suppress the generation of sludge by lowering the acidity (pH) of the plating liquid, but when the pH is 1.5 or less during zinc-nickel plating, a defect occurs that the plating material is cured by the generation of hydrogen. .

In addition, British Patent No. 189258 discloses that an additive such as acetylene alcohol or aromatic sulfonic acid can increase the Ni content and current efficiency of the plating layer and improve the uniformity. Operational defects due to sludge generation could not be improved.

Japanese Patent Application No. 59-211589 discloses a yellowish brown or blue-purple oxide incidentally to foreign substances by adding some ammonium chloride to the plating solution containing zinc chloride and nickel chloride as a main component of a chloride bath and lactate and changing plating conditions. It is described that the mixed precipitation of can be effectively suppressed. However, although sludge generation is suppressed at the beginning of the operation, there is a problem that sludge occurs over time.

In addition, Japanese Patent Laid-Open No. 2-057695 discloses gloss and ductility by adding RS (R′O) nH or S-((R′O) nH) ₂ (where R is an alkylene group having up to 24 carbon atoms). Improvements are described. However, the sludge of the solution is not suppressed, and the change of pH is severe when plating for a long time.

The inventors of the present invention aim to develop a plating solution that improves the above problems, and provide a plating solution containing zinc chloride, nickel chloride, and potassium chloride as a main component, so that the reactivity of the zinc anode is good, and thus sludge generation and It is an object of the present invention to provide a plating solution having good electrodeposition reaction and excellent surface appearance that can minimize side reaction hydrogen generation.

In order to achieve the above object, the present invention,

As a first aspect, with respect to the plating solution, a mixture of a zinc chloride compound and a nickel chloride compound having a sum of zinc and nickel concentrations of 150-200 g / L, a chloride and an additive liquid having an chlorine concentration of 300-350 g / L as an electrolyte, 0.1- And 2.0 ml / L, wherein the additive solution is prepared by adding an additive including sodium benzoate, saccharin, uric acid, and sodium sulfonate so that the mass ratio of the total mass of the additive to water is 1: 1.5-3. Alloy electroplating solution,

As a second aspect, the zinc-nickel alloy electroplating solution, characterized in that the concentration [Ni] of the plating solution and the concentration [Zn] of zinc satisfy the following conditions,

11.0% ≤ [Ni] / ([Ni] + [Zn]) × 100 (%) ≤ 15.0%

In a third aspect, the chloride is a zinc-nickel alloy electroplating solution, characterized in that selected from potassium chloride, calcium chloride, sodium chloride and mixtures thereof,

In a fourth aspect, the additive is a zinc-nickel alloy electroplating solution having a weight ratio of saccharin 1: 1.5-4.0, sodium sulfonate 1: 0.5-2.0, and uric acid 1: 0.01-0.1 to sodium benzoate. Provide,

As a fifth aspect, the zinc-nickel alloy electroplating solution was used to perform electrolysis under plating conditions of 50-70 ° C., pH 3.5-5.0, current density 40-200 A / dm 2, and relative flow rate 0.5-2.5 m / sec. It provides a method for producing a zinc-nickel alloy electroplated steel sheet, characterized in that the plating.

According to the present invention, the zinc-nickel alloy electroplating bath can maintain good cleanliness by preventing sludge of the plating solution, and further secure the surface quality, adhesion, and corrosion resistance of the plating layer.

Hereinafter, the present invention will be described in more detail.

The zinc-nickel alloy electroplating solution of the present invention includes a mixture of zinc chloride compound and nickel chloride compound, and chloride and additive solution.

In the water-soluble plating bath of the present invention, zinc and nickel are supplied to the plating solution including zinc chloride and nickel chloride, and the sum of the concentrations of zinc and nickel metal in the plating solution is preferably 150-200 g / L, more preferably. Preferably 160-180g / L. If the concentration of the metal is less than 150 g / L, continuous operation is impossible due to the surface film formation of the anode, the anode is uneven due to instantaneous film peeling, and a large amount of sludge of the solution by the film is generated. Moreover, when it exceeds 200 g / L, the adhesiveness of a plating layer will fall and electrodeposition cost will increase and it becomes unpreferable.

The nickel concentration [Ni] in the plating solution is preferably in the range of 0.11 to 0.15 relative to the total metal concentration (sum of nickel concentration [Ni] and zinc concentration [Zn]). That is, it is preferable to adjust so that the following formula may be satisfied.

11.0% ≤ [Ni] / ([Ni] + [Zn]) × 100 (%) ≤ 15.0%

If the nickel concentration to the metal concentration is less than 11.0%, the corrosion resistance in the plated layer is not good to ensure that the nickel content 10% or more is not preferable, and the nickel concentration to the metal concentration exceeds 15.0%. In this case, since the Ni content of the plating layer is more than 14% and peeling occurs during processing, it is not preferable, so it is preferable to satisfy the above conditions.

The zinc-nickel alloy electroplating solution of the present invention contains chloride as an electrolyte. The chloride comprises at least one compound selected from the group consisting of potassium chloride, calcium chloride, sodium chloride. Further, the chloride is preferably included so that the chlorine concentration is 300 ~ 350g / L (solution) relative to the plating solution, more preferably 310 ~ 340g / L (solution). When the concentration of chlorine in the plating solution is less than 300 g / L, the conductivity is poor, the adhesion of the plating layer is poor, the flaws are burnt on the surface, and the surface solubility of the anode is also poor, which is not preferable. In addition, when the concentration of chlorine in the plating solution exceeds 350 g / L, the solubility of the salt compound is poor and precipitates to cause flaws on the surface of the plating solution.

Furthermore, the electroplating solution of the present invention includes an additive liquid. The additive solution is composed of additives and water including sodium benzoate, saccharin, uric acid and sodium sulfonate, and the additive solution is added in an amount of 0.1-2.0 ml / L in the plating solution. When the additive liquid is added at less than 0.1 ml / L, the sludge of the plating solution is not suppressed and uniform electrodeposition is not secured, and the whiteness of the surface appearance is reduced, which is not preferable. Furthermore, in the case of containing an additive solution of 2.0 ml / L or more, excessive concentration prevents the metal ions from adsorbing to the base metal, resulting in poor adhesion, which is undesirable.

The additive constituting the additive liquid and water are preferably adjusted to have a ratio of 1: 1.5-3 by mass ratio. If the mass ratio of the additive to water is less than 1: 1.5, the effect of inhibiting hydrogen generation is lowered, and the improvement of plating efficiency is less than expected. And surface properties such as adhesion.

Furthermore, it is preferable to adjust sodium benzoate, saccharin, sodium sulfonate and uric acid as the additive component to have a specific mass ratio. By specific mass ratio, sodium benzoate and saccharin are adjusted to have 1: 1.5-4.0. If the mass ratio is less than 1.5, the plated layer is not finely polished and does not have glossiness. If the ratio is more than 4, the ion adsorption is severely disturbed and the adhesion of the plated layer is poor.

And, it is preferable that sodium benzoate and sodium sulfonate have a mass ratio of 1: 0.5-2.0. If it is less than 0.5, there is no improvement in whiteness because the plating structure is not controlled, and in the case of 2.0 or more, adhesion is reduced by ion adsorption interference. Not desirable

In addition, it is preferable to adjust the mass ratio of sodium benzoate and uric acid to 1: 0.01-0.1. If the mass ratio is less than 0.01, there is no effect of improving the whiteness of the plating layer, and if it exceeds 0.1, a dark brown pattern is generated on the surface, and it is preferable to have a mass ratio in the above range.

In the production of zinc-nickel alloy electroplated steel sheet using the plating solution of the present invention, the plating bath temperature 50-70 ^o C, pH 3.5-5.0, current density 40-200A / dm ² and the plating solution for the plated body It can be produced by electroplating under the plating conditions of the relative flow rate of 0.5 ~ 2.5m / sec.

When the temperature of the plating bath is out of the above range and less than that, the solubility of various salts is lowered, and the content of nickel, which is an alloy metal, is lowered in the plating layer. There is a serious problem.

When the pH of the plating bath is less than 3.5, the plating efficiency decreases due to the generation of sorghum in the cathode, and black comb-patterns are formed on the surface of the plating layer. When the plating bath exceeds 5.0, the formation of hydroxides and the contamination of the plating solution are severe. Occurs.

When the relative flow velocity of the plating solution to the steel plate, which is the plated body of zinc-nickel alloy plating, is less than 0.5 m / sec, the plating property is deteriorated due to coarsening of the plating crystals and burning of the plating layer, and 2.5 m. When it exceeds / sec, it is beyond the practical range, and it is preferable to have a flow velocity of the said range.

Furthermore, when the current density is less than 40 A / dm ² , the glossiness of the plating layer is lowered, and nickel in the plating layer is excessively precipitated. However, if the current density is increased, the plating speed is increased and the productivity is improved, but if it exceeds 200 A / dm ² , a burning phenomenon occurs in the plated layer, and a problem occurs in contact between the steel sheet and the current collector.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, it will be understood that the following examples are merely specific examples of the present invention, and are not intended to limit the present invention to the following.

Example

In the following examples, physical property evaluation was performed as follows.

Whiteness of Plated Steel Sheet

It was measured with a Color and Color Difference Meter, and it was judged as bad if it was 68 or less, and good if it was 68 or more.

Glossiness

It was measured with a glossmeter. As a result of the measurement, it was judged that it was defective on the basis of 70 or less and good on or more.

Plating  Adhesion

The plated steel sheet was bent at an angle of 60 °, and the tape was attached to the inside, followed by observing whether or not the plating component appeared on the tape when peeled. .

Plating efficiency

The deposited metal with respect to the amount of applied current was expressed as a ratio, and the plating efficiency was evaluated. As a result of calculating with the formula of (the actual precipitation amount / theoretical precipitation amount) x 100, when it was less than 95%, it judged as bad, and when it was 95% or more, it was judged as good.

Corrosion resistance

A salt spray test was conducted in accordance with JIS Z 2371. After 200 hours in a salt sprayed room, the presence of red rust was observed to determine whether red rust occurred.

Plating amount Sludge  Occur

It was judged by observing whether or not the turbidity of the plating solution was increased after 2 hours of plating, and when the turbidity increase was greater than 3NTU (Nephelometric Turbidity Unit), it was judged to be poor and less than that.

Example  One

The cold rolled steel plate was a metal, and the sum of the concentrations of zinc and nickel in the plating solution was 165 g / L, and the plating solution was adjusted to Ni / (Ni + Zn) = 0.12, and the plating temperature was 60 ° C., pH 4.5 and current density was 80 A /. dm ² and a flow rate of 1.5 m / sec were plated under the plating additive and plating solution conditions shown in Table 1 to prepare a plated steel sheet having a plating amount of 30 g / m ² .

The physical properties of the surface whiteness, glossiness, plating material adhesion and plating efficiency of the coated steel sheet were evaluated, and the results are shown in Table 1.

[Table 1] Quality Characteristics of Zinc-Nickel Alloy Electroplating Materials

Example  2

The solution was added a cold-rolled steel sheet possessing a metal 0.5ml / L was added, and the temperature 60 ℃, flow rate maintained at 1.5ml / sec and subjected to plating in the plating solution concentration and the plating conditions shown in Table 2, coating weight of 30g / m ² A plated steel sheet was prepared.

The whiteness, glossiness, adhesiveness, and corrosion resistance of the obtained plated steel sheet were evaluated, and the results are shown in Table 2.

[Table 2] Characteristics of plating materials according to plating solution and conditions of zinc-nickel electroplating

Example  3

The cold rolled steel sheet was kept at a pH of 4.5, a temperature of 60 ° C. and a flow rate of 1.5 m / sec, the plating current was maintained at 80 A / dm ² , and the plating was continuously performed for 2 hours under the plating solution concentrations and plating conditions shown in Table 3. The turbidity of the solution due to sludge generation of the plating solution was investigated.

[Table 3] Plating solution sludge after zinc-nickel electroplating for a long time

As shown in Tables 1, 2 and 3 shown in the Examples, the plating solution components and conditions exhibited an excellent sludge suppression effect and plating quality within the range defined by the present invention. As described above, according to the present invention, the zinc-nickel alloy electroplating solution can maintain good cleanliness by preventing sludge of the plating solution, and can secure the surface quality, adhesion, corrosion resistance and the like of the plating layer.

Claims (5)

In the plating solution, a mixture of zinc chloride compound and nickel chloride compound having a sum of zinc and nickel concentrations of 150-200 g / L, and an electrolyte containing 0.1-2.0 ml / L of chloride and additive solution having a chlorine concentration of 300-350 g / L as an electrolyte , The additive solution is a zinc-nickel alloy electroplating solution, characterized in that the additives including sodium benzoate, saccharin, uric acid and sodium sulfonate are prepared so that the mass ratio of the total weight of the additive to water is 1: 1.5 to 3 The zinc-nickel alloy electroplating solution according to claim 1, wherein the nickel concentration [Ni] and the zinc concentration [Zn] in the plating solution satisfy the following conditions. 11.0% ≤ [Ni] / ([Ni] + [Zn]) × 100 (%) ≤15.0% The zinc-nickel alloy electroplating solution of claim 1, wherein the chloride is selected from potassium chloride, calcium chloride, sodium chloride and mixtures thereof. The zinc-nickel alloy electroplating solution of claim 1, wherein the additive has a weight ratio of saccharin 1: 1.5-4.0, sodium sulfonate 1: 0.5-2.0, and uric acid 1: 0.01-0.1 to sodium benzoate. . The zinc-nickel alloy electroplating solution of any one of claims 1 to 4 using a temperature of 50-70 ° C., pH 3.5-5.0, a current density of 40-200 A / dm ² , and a relative flow rate of 0.5-2.5 m / sec. Method for producing a zinc-nickel alloy electroplating steel sheet, characterized in that the electroplating under the plating conditions of.