KR100419659B1 - A plating solution for blackening zinc-nickel alloy coated steel sheet and electroplating method for zinc-nickel steel sheet - Google Patents

Abstract

The present invention relates to a plating solution composition for producing zinc-nickel black plated steel sheet having excellent blackness and corrosion resistance, and a plating method of zinc-nickel steel sheet using the same.

Total metal ion concentration is 80-150 g / l, nickel ion concentration is 10-15wt%, chlorine ion concentration is

Zinc-nickel plating solution of zinc chloride, nickel chloride and potassium chloride of 240-320 g / L; 0.5-4.0 g / l of at least one polyethylene glycol having a molecular weight ranging from 600 to 2000 based on the total volume of the plating solution; and a total amount of one or more of saccharin, naphthalene sulfonic acid and sodium benzoate 0.1-2.0 g / The plating solution composition for the production of zinc-nickel black plated steel sheet and the composition of which the pH is 2.0 to 3.5 and the temperature is adjusted to 50 to 70 ° C. and the moving speed of the continuous steel is 0.5 to 2.5 m / sec, and the current density is A method of electroplating a zinc-nickel steel sheet in the range of 50-150 A / dm ² is provided.

By plating with a plating solution composition for manufacturing a chloride-based black plated steel sheet to which the additive is added, a black plated steel sheet having excellent blackness and corrosion resistance is prepared without a separate subsequent process treatment. Plating at high current densities increases the productivity of the plating process, shortens the process and reduces manufacturing costs.

Description

Plating solution composition for manufacturing zinc-nickel black plated steel sheet and electroplating method of zinc-nickel-based steel sheet using same

The present invention relates to a plating solution composition for the production of zinc-nickel black plated steel sheet and a steel plate plating method using the same, and more particularly, to a zinc-nickel black plated steel sheet production with excellent blackness and corrosion resistance, and a zinc-nickel system using the same. It is related with the plating method of a steel plate.

Surface-treated steel sheet produced by continuous plating is applied to various surface-treated steel sheet to meet the demand of the application by applying various post-treatment techniques. In particular, black plated steel sheet is widely used as a steel sheet for home appliances such as audio and video, and the demand is increasing due to cost-saving and environmentally friendly plated steel sheet that can be used without coating treatment.

Advanced steel companies such as Japan use a method of forming zinc oxide and nickel oxide in the plating layer by plating black chromium using zinc-nickel alloy plated steel sheet or dissolving the plating layer by spraying or anodizing. In addition, zinc-cobalt-molybdenum alloy plated steel sheet may be anodized, zinc-magnesium alloy plated black chromate-treated, or zinc-coated steel plate to produce antimony-nickel substitution to produce black plated steel sheet.

Since the above conventional technologies perform black chromium plating, black chromate treatment, or anodizing treatment using galvanized or zinc-based alloy plated steel sheets, additional manufacturing equipment and processes are required and a separate electrolyte must be used. In addition to the increase in manufacturing costs, using a chromium solution or the like causes environmental problems.

Accordingly, an object of the present invention is to provide a plating solution composition that can produce a black plated steel sheet directly in the plating process without additional equipment and processes.

Another object of the present invention is to provide a plating solution composition for manufacturing zinc-nickel black plated steel sheet which is environmentally friendly and excellent in blackness and corrosion resistance.

Still another object of the present invention is to provide a plating solution composition for manufacturing zinc-nickel black plated steel sheet, which does not require a separate coating treatment.

Furthermore, another object of the present invention is to provide an electroplating method of a steel sheet using the plating solution composition.

Figure 1 is a photograph showing the plating layer structure of the steel sheet prepared by the plating solution composition and method in the present invention.

According to one aspect of the invention,

Total metal ion concentration is 80-150 g / l, nickel ion concentration is 10-15wt%, chlorine ion concentration is

Zinc-nickel plating solution of zinc chloride, nickel chloride and potassium chloride of 240-320 g / L;

0.5-4.0 g / l of at least one polyethylene glycol having a molecular weight ranging from 600 to 2000 as a main additive based on the total volume of the plating solution; and

0.1 to 2.0 g / l of saccharin, naphthalene sulfonic acid and sodium benzoate as a minor additive, or a total amount of two or more thereof;

A plating solution composition for producing zinc-nickel black plated steel sheet is provided.

According to another aspect of the present invention,

The plating solution composition has a pH of 2.0 to 3.5 and a temperature of 50 to 70 ° C., and a continuous steel strip has a moving speed of 0.5 to 2.5 m / sec and a current density of 50 to 150 A / dm ² for zinc electroplating. -Electroplating method of nickel-based steel sheet is provided.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail.

In order to impart excellent blackness and corrosion resistance to the zinc-nickel steel sheet, specific additives are used in the plating solution, and according to the method of the present invention, it is excellent in blackness and corrosion resistance under high current density conditions by using a continuous electroplating facility. In addition, eco-friendly black-plated steel sheet will be manufactured economically.

The plating solution in the plating solution composition for producing zinc-nickel black plated steel sheet of the present invention is composed of zinc chloride, nickel chloride and potassium chloride, and the total metal ion concentration in the plating solution is 80 to 150 g / l, and the nickel ion concentration is 10 to 15 wt. % And chlorine ion concentration is formulated to be 240 ~ 320g / ℓ.

The total metal ion concentration in the plating solution represents the sum of the concentrations of zinc and nickel ions and is preferably 80 to 150 g / l. At 80 g / l or less, as the crystal structure of the plating layer becomes coarse at a high current density, plating adhesion becomes poor, and when it is 150 g / l or more, the nickel content of the plating layer is lowered and blackness and corrosion resistance are reduced.

In addition, it is preferable that the concentration of nickel ions in the plating solution is 10 to 15 wt% in order to obtain a black plating layer by a uniform oxide film. When the concentration ratio of nickel ions is less than 10wt%, the blackness is lowered. If the concentration of nickel ions is 15wt% or more, the color of the plating layer becomes uneven, and cracks are also formed in the plating layer.

The concentration of chlorine ions in the plating solution is preferably in the range of 240 to 320 g / l.As a result, the conductivity of the plating liquid is lowered at 240 g / l or less, making it difficult to perform high current density plating. This is because potassium chloride or the like precipitates on the conductive rolls.

The following components are added to the plating solution as described above to give blackness and corrosion resistance during plating. That is, as the main additive, at least one polyethylene glycol having a molecular weight in the range of 600 to 2000 based on the total volume of the plating solution and at least one component of saccharin, naphthalene sulfonic acid, and sodium benzoate is added as a secondary additive.

Polyethylene glycol as a main additive in the plating solution additive of the present invention serves to blacken the plating layer while adjusting the nickel content of the plating layer to 3 to 5 wt.%. In particular, the polyethylene glycol is used in the range of 600-2000 molecular weight, if the molecular weight is out of the above range the blackness is reduced or non-uniform. In addition, the use of polyethylene glycol having a molecular weight of 600 or less does not sufficiently exhibit the intended effect. If the molecular weight is 2000 or more, foaming becomes severe in the plating solution, and nickel does not vacate in the plating layer. The same effect can be obtained even if it mixes and uses different types of polyethyleneglycol as long as it has the molecular weight of the said range.

It is preferable to add polyethylene glycol at 0.5 to 4.0 g / l, but the above addition effect cannot be obtained at 0.5 g / l or less, and when it is 4.0 g / l or more, foaming becomes severe in the plating solution and the nickel content of the plating layer is increased. Degrades.

Saccharin, naphthalenesulfonic acid and sodium benzoate as an additive additive serve as an auxiliary function of finely homogenizing the crystal grains of the plating layer and promoting the formation of a uniform oxide film. One or two or more of saccharin, naphthalenesulfonic acid and sodium benzoate Can be mixed and used.

It is preferable to use the said subadditive in the amount of 0.1-2.0 g / L. The effect is not obtained at 0.1 g / l or less, and at 2.0 g / l or more, bubbles are generated in the plating solution and the nickel content of the plating layer decreases. In particular, when using saccharin alone, it is preferable to manage the addition amount at 1.0 g / l or less because the tendency of the nickel content of the plating layer to decrease is increased.

In applying the black plating composition for zinc-nickel steel sheet to which the main additive and the subadditive as described above are added to the steel sheet, the pH of the plating solution is adjusted to be in the range of 2.0 to 3.5. When the pH is less than 2.0, the generation of hydrogen is promoted at the cathode, thereby lowering the plating efficiency and uneven surface quality. At pH above 3.5, the blackness decreases when the nickel content of the plating layer is increased.

In addition, the plating solution temperature is preferably controlled to 50 ~ 70 ℃, if the temperature below 50 ℃, solubility of various salts, including potassium chloride is lowered, and the nickel content of the plating layer is also reduced, above 70 ℃ the evaporation of the plating solution is severe, worsening the working environment The color of the plating layer is also nonuniform.

Under the plating conditions, when the moving speed of the steel plate to be plated is 0.5 m / sec or less, the supply of metal ions is not smooth at high current density, resulting in coarsening of the plating crystals or burning of the plating layer. Since the surface color becomes uneven, such as flow pattern generation, the plating layer is preferably plated at a moving speed of 0.5 to 3.0 m / sec.

In addition, when the current density is 50 A / dm ² or less, the plating speed is low to reduce productivity and the nickel content of the plating layer is increased. When the current density is 150 A / dm ² or more, the color is uneven near the edge of the steel sheet and the adhesion is poor. Since coarse grains are formed, it is preferable to electroplat with a current density in the range of 50 to 150 A / dm ² .

The zinc-nickel-based black plated steel sheet produced by the present invention has a nickel content of 3 to 5 wt% and a blackness and corrosion resistance, unlike a conventional zinc-nickel alloy plated steel sheet having a nickel content of 10 to 15 wt%. It forms very fine grains with excellent and uniform oxide film.

In addition, the black plated steel sheet of the present invention can be used without a separate coating process in a processing company, such as home appliances, cost is reduced, it shows excellent quality characteristics such as blackness, corrosion resistance as an environmentally friendly steel sheet.

Hereinafter, the present invention will be described in detail through examples.

Example

Cold rolled steel sheet with annealing thickness of 0.7mm is used as the plated body, degreasing and pickling in continuous electroplating equipment, and then moving speed of steel sheet is 1.0 ~ 2.0 m / sec in continuous plating bath using soluble zinc anode. The current density was 60 to 120 A / dm ² , the plating deposition amount was 20 to 30 g / m ² , and the plating solution was electroplated by forming as shown in Table 1 below.

After electroplating, the nickel content, blackness (Lightness, L-value) of the plating layer, and salt spray corrosion resistance (SST, the area of red blue generation at 200 hours of salt spraying) were analyzed and the results are shown in Table 2 below.

division Plating solution composition (g / ℓ) pH Temperature (℃) TM Ni ²⁺ % CI ^- PEG concentration (molecular weight) SA NS NB Comparative example One 100 14 280 3.0 60 2 70 12 270 2.0 (1000) 0.5 0.3 0.2 2.5 65 3 180 14 270 1.5 (1500) 0.5 0.5 3.0 65 4 100 14 200 5.0 (400) 0.5 0.5 3.0 60 5 80 12 280 2.0 (1000) 0.2 0.3 4.0 70 Inventive Example 6 80 12 260 2.0 (1500) 0.5 3.0 60 7 100 14 280 1.0 (600 + 1500) 0.2 0.3 2.5 60 8 100 14 280 3.0 (600 + 1000) 0.2 0.2 0.1 3.5 65 9 140 15 300 0.7 (1000 + 1500) 0.5 0.3 3.0 60 10 120 14 300 0.7 (2000) 0.2 0.3 2.0 65

division Comparative example Inventive Example One 2 3 4 5 6 7 8 9 10 Plating layer Ni% 12 4.5 2.5 1.5 7.5 4.3 3.8 3.2 3.5 3.4 Blackness ¹⁾ Χ О О △ △ О О ◎ ◎ О Brine corrosion resistance ²⁾ ◎ △ △ Χ О ◎ ◎ О ◎ О

1) Blackness (L-value): ◎ 5 or less, О 10 or less, △ 30 or less, Χ 30 or more

2) SST 200 hours red blue area: ◎ No occurrence, О 10% or less, △ 30% or less, Χ 30% or more

As can be seen from Table 2, the inventive examples (6 to 10) in accordance with the present invention, unlike the comparative examples (1 to 5), the nickel content of the plating layer is stable in the range of 3 to 5 wt%, and both blackness and salt spray corrosion resistance. It can be seen that excellent.

In addition, FIG. 1 shows a photograph observing the plating layer crystal structure of the black plated steel sheet formed by using the plating solution having the composition of Inventive Example 9 at 200 times, wherein very fine uniform plating grains were formed.

By plating using the black plating solution composition for the chloride-based zinc-nickel steel sheet to which the additive of the present invention is added, it is possible to prepare a black plate steel sheet having excellent blackness and corrosion resistance without further processing. In addition, by plating at a high current density, the productivity of the plating process is increased and the manufacturing cost is also reduced because the process is shorter than in the prior art.

Claims (3)

Zinc-nickel plating solution of zinc chloride, nickel chloride and potassium chloride with a total metal ion concentration of 80-150 g / l, nickel ion concentration of 10-15 wt%, and chlorine ion concentration of 240-320 g / l; 0.5-4.0 g / l of at least one polyethylene glycol having a molecular weight ranging from 600 to 2000 as a main additive based on the total volume of the plating solution; and Plating solution composition for the production of zinc-nickel black plated steel sheet with a total amount of one or two or more of saccharin, naphthalene sulfonic acid and sodium benzoate as an additive additive; 0.1-2.0 g / l; The composition of claim 1, wherein when saccharin is used alone as the subadditive, saccharin is used in an amount of 0.1-1.0 g / L based on the volume of the total plating solution. The plating solution composition of claim 1 has a pH of 2.0 to 3.5 and a temperature of 50 to 70 ° C., and a continuous steel strip has a moving speed of 0.5 to 2.5 m / sec and a current density of 50 to 150 A / dm ^{2 for} electroplating. Electroplating method of zinc-nickel steel sheet.