KR101173879B1 - Multi-functional super-saturated slurry plating solution for nickel flash plating - Google Patents

Abstract

PURPOSE: A multi-functional supersaturated slurry plating solution for nickel flash plating is provided to supplement nickel ion and maintain iron components below a predetermined level. CONSTITUTION: A multi-functional supersaturated slurry plating solution for nickel flash plating is prepared by adding alkali salt to a nick flash plating solution. The nickel flash plating solution contains nickel salt, a conductivity assistant, a complexing agent, and a co-deposition agent for supporting the co-deposition of iron ion. The alkali salt is prepared by mixing caustic soda, caustic postash, sodium carbonate, and potassium carbonate at the ratio of 10:2:1:1.

Description

Multifunctional supersaturated slurry plating solution for nickel flash plating {MULTI-FUNCTIONAL SUPER-SATURATED SLURRY PLATING SOLUTION FOR NICKEL FLASH PLATING}

The present invention relates to a pretreatment process performed to improve the film characteristics of electrogalvanizing as a complementary technology of the previously filed 10-2008-0038705.
More specifically, the present invention is for drying the nickel flash plating solution used as a base plating solution for the base iron during the pretreatment process, inhibiting acidification of the solution as a one-component replenishment solution, and improving the quality of the electrolytic zinc for longer life of the solution. It is related to the surface treatment method of steel sheet.

In general, steel sheets are widely used as structural materials for automobiles, home appliances, and building materials due to their excellent mechanical strength, good workability, and abundant resources. However, steel sheets themselves are extremely poor in corrosion resistance, and thus their lifespan is mainly extended through galvanizing. . Generally, the thicker the galvanizing thickness is, the better the corrosion resistance to protect iron is. However, it is limited and uneconomical to provide high corrosion resistance to the steel sheet by the zinc deposition amount alone. Therefore, in recent years, the application of electro-zinc plating technology, which can obtain high corrosion resistance with a relatively small amount of zinc adhesion, compared to hot-dip galvanizing, has been widely used in parts plating from steel plating.

 However, if the thickness of the zinc plating is thin, the adhesion and hiding power of plating are inevitably deteriorated, so that defects existing on the surface of the base iron remain intact even after plating. Corrosion resistance, as well as the smoothness and beauty of the plating surface cause.

In order to solve the problem of surface defects, including the problem of visual damage of galvanized steel sheet manufactured by electro-galvanizing, nickel flash plating is performed before electro-galvanizing. This nickel flash plating not only smoothes the surface of the base iron, but also prevents various impurities present on the surface of the base iron from electro-galvanizing and then coming out of the surface of the electro-galvanizing. To get

The nickel flash plating described above is based on nickel plating in principle. Nickel plating is used for the purpose of anticorrosion and decoration for steel and copper, and is also used for underplating during chromium plating. In addition, nickel coating has a good color, relatively little discoloration, and good hardness, and has good mechanical properties. Such nickel plating is mainly performed in a watt bath, a wood bath, a spam acid bath, a black nickel bath, and the like, and is performed by an electroplating method in a plating bath composed mainly of nickel sulfate and nickel chloride.

However, the nickel plating has to go through a difficult process such as adjusting the acidity (pH) and the cathode current density of the plating bath. Sometimes, the plating layer does not exhibit the perfect concealment characteristics to be achieved depending on the composition of the plating solution and the plating conditions. do. In fact, large-scale mass production facilities for nickel flash plating use insoluble anodes for the convenience of the process. In this case, hydrogen ion is generated by anode reaction [1] and plating time is gradually increased due to the increase of plating time, which causes various problems. do.

Reaction Scheme 1

H ₂ O → 1 / 2O ₂ + 2H ⁺ + 2e-

Cathode Reaction

Ni ^{2 +} + 2e- → Ni

2H ⁺ + 2e- → H ₂

At the anode, the reaction of nickel electrodeposition [2] and the reduction reaction of hydrogen ion [3] simultaneously compete to reduce the concentration of hydrogen ions produced at the anode, but as the proportion of this reaction increases, the hydrogen ion decreases but the electrodeposition of nickel is reduced. The amount is so small that the current efficiency of the cathode is reduced.

The acidification of the plating liquid composition directly affects the plating properties, but in particular, the iron material is corroded to continuously increase the iron content in the plating solution. When iron is concentrated in the plating solution, sludge is formed in the plating solution, which in turn causes color change of the plating layer and poor plating. In addition, it shortens the use time of the plating liquid and causes a problem of changing the plating liquid regularly. It not only lowers the quality of the product but also lowers productivity and raises manufacturing costs. Generally, when the iron concentration reaches 500 ppm, the problem starts to occur in nickel flash plating, and when the concentration reaches 1000 ppm, the degree is very serious. Increasing the impurities may increase the internal stress of the nickel plating layer, which may cause fine cracks in the plating layer, which may cause deterioration of corrosion resistance and poor adhesion to the zinc plating layer.

The acidification of the plating solution described above can be controlled by replenishing an alkaline solution such as caustic soda, but as time goes by, alkali ions are concentrated, which causes another problem. Meanwhile, in order to prevent acidification of the solution and replenish nickel ions, powdered nickel carbonate is added to the plating solution. However, the solubility of the nickel carbonate particles, which is not dissolved, causes plating failure. Therefore, in order to carry out such nickel flash plating effectively and in the long term, it is possible to suppress the concentration of impurities, especially iron, to supplement the consumed nickel ions, and to develop a multifunctional supplementary nickel flash plating solution that can prevent acidification of the solution. need.

Korean Patent No. 10-0554147 discloses nickel flash plating by adding ethylene diamine tetraacetic acid as a complexing agent in nickel flash plating to form a complex salt such as iron, tin, and lead as impurities in the solution, thereby suppressing electrodeposition of impurities on the plating layer. Disclosed is a technique for producing a cold rolled steel sheet having good adhesion and surface quality during phosphate treatment and painting of steel sheets. Although this technique is expected to have good effects on post-treatment phosphate treatment and painting work by suppressing the vacancy of impurities, it is not intended for zinc electroplating, and it is not particularly a method for suppressing acidification of nickel flash plating solution. .

Korean Patent Application No. 10-2008-0038705, which is the basis of this application technology, combines the role of additives such as complexing agents, vacancies, antioxidants, etc., to optimize the technical functions of one-component nickel flash plating solution. Plating provides the best technology. However, there is a limit in inhibiting the acidification of the plating solution, and there is a problem in that it is difficult to secure the best quality of the galvanized steel sheet including corrosion resistance and whiteness due to side effects of acidification of the solution in the long term, that is, current efficiency decrease and increase of impurities.

The nickel flash plating solution currently used is based on the existing nickel plating solution composition. Water-soluble single or complex nickel salts are used as a source of nickel in the composition of the plating bath used for continuous plating, such as the production of galvanized steel sheet, and as additives, many of them play different roles such as conductivity aids, pH buffers, and polishes. Organic and inorganic compounds are used in combination.

Among the plating liquid components, the most important one is nickel chloride, nickel sulfate, nickel carbonate, nickel nitrate, nickel acetate, nickel oxide, and the like, and in some cases halogen compounds such as bromine, iodine, and fluorine are used. Among them, nickel sulfate is the main component of Watts bath, which is the most used, and concentration and plating rate are closely related. Nickel chloride has a great influence on anode dissolution and electrolyte conductivity improvement. Nickel salts are used either alone or in mixtures. For nickel sulfate the concentration is adjusted between approximately 200 g / l and 500 g / l, with a suitable concentration between 250 g / l and 450 g / l and more precisely between 300 g / l and 400 g / l. Is adjusted in.

The nickel salt and then added as a constituent of the plating bath are conductivity aids to improve the conductivity of the solution. Potassium chloride, sodium chloride, ammonium chloride, ammonium sulfate and the like are used as the conductivity aid in the nickel flash plating solution.

As the pH buffer, boric acid is mainly used. The boric acid functions not only to adjust the pH of the solution but also to increase the color, uniformity, and flexibility of nickel plating.

In addition, chlorides or sulfides such as manganese, aluminum, beryllium, and the like are added as various kinds of precipitation aids to refine the crystals of the electrodeposited material or to smooth and delicate plating.

In addition to the above components, various surfactants or polishes are used to increase the smoothness, sealability, uniformity, flexibility and mechanical properties of the plating. As surfactants and brightening agents, water-soluble organic compounds are used, for example, sulfonic acid compounds such as benzenedisulfonic acid, benzenetrisulfonic acid, naphthalindisulfonic acid, naphthalintrisulfonic acid, or benzenesulfamide, benzenesulfimide , Sulfur-containing amides such as saccharin, and compounds containing an aldehyde (C = O) group, an olefin (C = C) group, an acetylene (C≡C) group as functional groups, such as formaldehyde, coumarin, butyne Unsaturated compounds such as diols. These organic additives are mostly decomposed during plating and inserted into the plating layer or can be consumed by electrochemical reduction.

In addition to the composition of the liquid in nickel flash plating, the determining characteristics of the plating characteristics include plating conditions such as current density, plating liquid temperature and pH, and plating time.

The current density is an important factor in determining the thickness or nickel plating amount of the nickel plating layer. Depending on the nickel ion concentration in the plating solution and the plating time, plating is performed in a wide range from about 1 A / dm 2 to 10 A / dm 2, but mainly between 4 A / dm 2 and 8 A / dm 2.

The temperature of the plating liquid is controlled between 50 ° C and 60 ° C and plating is possible at pH 1-6, but preferably adjusted to pH 2-5 as much as possible.

Plating time is performed between 0.1 and 40 seconds considering the solution concentration and the plating amount. The longer the plating time is, the higher the plating thickness or the amount of plating is required, and in some cases, poor plating may be made by forming spherical or dendritic crystals on the plating surface. Current industrial plating equipment in mass production performs plating within a few seconds by precisely controlling the distance between electrodes, the moving speed and current density of steel sheet. Pulse plating is also used to convert the current density periodically, high and low, within the permissible range for uniform plating.

The amount of plating is generally measured by measuring the thickness, and the unit is used in μm (millionths of meters). Nickel flash plating, however, has a very thin plating thickness, which makes it difficult to accurately measure the amount of coating. In particular, the plating of the steel plate to be plated in the continuous plating apparatus may be more rational because the thickness thereof is relatively uniform. The plating weight of nickel flash plating ranges from 20 mg / m 2 to 500 mg / m 2 depending on the application, but is generally plated between 100 and 250 mg / m 2.

As described above, the matters described as the background art are merely for the purpose of improving the understanding of the background of the present invention, and should not be taken as acknowledging that they correspond to the related arts already known to those skilled in the art. .

The present invention is based on the recognition of the problems of the prior art as described above, in addition to the main function of replenishing nickel ions, in addition to controlling the strong acidification of the solution inevitably occurs in the plating apparatus using the current insoluble anode, plating solution It provides a multifunctional supersaturated slurry plating solution for nickel flash plating that can maintain impurities below a certain level, particularly iron.

In another aspect, the present invention provides a new multi-functional supersaturated slurry plating solution for nickel flash plating to enable long-term use of the plating solution, as well as to improve the plating quality as well as the productivity and economy.

Multifunctional supersaturated slurry plating solution for nickel flash plating according to the present invention for achieving the above object, the alkali salt is added to the nickel flash plating solution is added to the nickel salt, conductivity aids, complexing agents, vacancy agents to help the vacancy of iron ions It is characterized by one.
The alkali salt is caustic soda, caustic caustic, sodium carbonate, calories carbonate is added in a ratio of 10: 2: 1: 1 by weight, the addition amount is added in the range of 30 ~ 60g / L It features.
The multifunctional supersaturated slurry plating solution for nickel flash plating according to the present invention is characterized in that the weight ratio of the nickel metal in the slurry as a solid content and the liquid solution is controlled in the range of 40 to 60:60:40.
The slurry particles are characterized by having a Gaussian distribution with a peak of 5 µm.
The complexing agent may be prepared by adding any one or a combination of gluconic acid, citric acid, tartaric acid, thiourea, and imidazole, and added at a concentration of 0.5 to 10 g / l, and the vaccinating agent is ethyleneimine or gluconate. C. Any one of sodium citrate and sodium alginate, or a combination thereof, may be prepared and added at a concentration of 0.1 to 50 g / l. The nickel salt may be nickel sulfate, nickel carbonate, nickel sulfate, nickel acetate, or nickel formate. , Nickel fluoride, nickel fluoride, or any one of the composites are prepared and added to a concentration of 10 ~ 200g / l, the conductivity aid, sodium sulfate, ammonium sulfate, sulfamic acid, boric acid, ammonium fluoride, sodium formic acid, Ammonium formate, ammonium phosphate, potassium sulfate is prepared from any one or a combination thereof is added, characterized in that it is added at a concentration of 10 ~ 200g / L.

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According to the present invention as described above, it is possible to control the replenishment and pH of nickel without frequently replacing the nickel flash plating solution, it is possible to prevent the concentration and precipitation of iron by removing the iron gradually increasing in the plating solution.

In addition, the nickel flash plating solution according to the present invention has no problem even after long-term use, and can produce an electrogalvanized steel sheet excellent in corrosion resistance, adhesion, hiding property and whiteness.

1 is a slurry particle distribution of nickel slurry plating solution,
2 is a pH change of the plating solution according to the plating time,
3 is a cathode current efficiency according to the pH of the plating solution,
4 is a view showing a change in the pH and nickel metal ion concentration of the plating solution when the slurry plating solution is used for a long time.

Hereinafter, with reference to the accompanying drawings looks at in more detail with respect to the present invention.

Composition of Nickel Flash Plating Solution

First, the composition of the nickel flash plating solution will be described.

Iii) nickel salt

Nickel contained in the nickel flash plating solution is supplied in salt form.

Examples of the salts include nickel sulfate [NiSO 4? 6 H 2 O], nickel carbonate [NiCO 3? 2 Ni (OH) 2? 4H 2 O], nickel nitrate [Ni (NO 3) 2? 6H 2 O], ammonium sulfate [Ni (SO 3 NH 2) 2? 4H 2 O], And various organic and inorganic acid salts such as nickel sulfamate [(H 2 NSO 3) 2 Ni 4 H 2 O], nickel acetate and nickel formate, and mixtures thereof.

The nickel concentration in the nickel flash plating solution is 10 to 200 g / l, preferably 30 to 100 g / l. If the concentration of nickel metal is higher than 200g / l, the current efficiency is too high and plating of the high current part is carried out, and the activity of the metal is also increased, resulting in the precipitation of metal crystals on the plating surface, resulting in uneven plating surface and cracking. When is less than 10g / ℓ low current efficiency is poor plating on low current site and pin holes or pit on the plating surface is likely to occur.

Ii) conductivity aids

In nickel flash plating, a conductive salt is added to the plating solution as an aid to improve the electrical conductivity of the plating solution.

The conductive salt should be appropriately selected according to the type of nickel metal salt, and sulfate, ammonium, and boric acid salts may be used, and more specific examples thereof include ammonium sulfate, ammonium chloride, boric acid, ammonium phosphate, potassium sulfate, or the like. Mixtures thereof.

The conductive salt is contained in a concentration of 10 ~ 200g / L, preferably 50 ~ 100g / L in the plating solution based on the nickel concentration of 100g / L in the plating solution. If the concentration of the conductive salt is higher than 200 g / l, the current efficiency is increased, so that cracks or uneven plated metal particles are uneven and the concentration of the conductive salt is lower than 10 g / l due to the high internal stress of the plating layer in which the plating of the high current site is formed. If it is low, the plating of low-current site | part is not easy and corrosion resistance, adhesiveness, etc. are inferior.

Iii) complexing agent

A complexing agent is added in the plating solution to prevent the nickel flash plating solution containing various components from being deteriorated due to physicochemical reactions between the components and to prevent the stability from deteriorating with prolonged use and storage.

According to the present invention, a material having a strong complexing property with iron ions, which is an impurity in the nickel flash plating solution, is used as the complexing agent. In other words, iron ions are oxidized due to low stability and are easily precipitated with iron hydroxide in the plating solution. Complexing agents are stabilized and vacancies of iron ions in combination with iron ions. Appropriate ingredients should be selected. As such a complexing agent, an amine system, citric acid system, amino acetic acid system, or a mixture thereof may be used. More specifically, gluconic acid, alginic acid, citric acid, tartaric acid, and the like may be used.

The complexing agent is added to the nickel flash plating solution at 0.5 to 10 g / l, preferably 3 to 7 g / l. When the concentration of the complexing agent is higher than 10 g / l or lower than 0.5 g / l, defects in the plating surface as well as the equilibrium of the plating liquid are broken, thereby shortening the life of the plating liquid.

Iii) Vacancies

Although the above complexing agent also functions as a vacancy agent, that is, as a component for causing iron to be electroplated with nickel, it is more preferable to use a vacancy agent which shows a more effective feature for electroprecipitation of iron ions. . As such a vaccinating agent, ethyleneimine, sodium gluconate, sodium citrate, sodium alginate, and a complex salt thereof can be used, and is added to the nickel flash plating solution at 5 to 50 g / l.

Iii) antioxidants

Antioxidants are added to prevent the generation of iron hydroxide due to the oxidation of iron ions, which together with the complexing agent described above contribute to stabilizing the iron ions in the plating solution. Such antioxidants may not be strong reducing agents but should be selected as a component that can at least make the electrical properties of the solution into a reducing atmosphere. These antioxidants may be benzoic acid or fluorine resin, and 0.1 ~ 25g / is added in liters.

표면) Surface improving agent (leveling agent) and stress reducing agent

To the nickel flash plating solution, a surface improving agent and a stress reducing agent are added to form an excellent plating film.

The surface improving agent is added to suppress the generation of gas at the anode and to provide a uniform electron supply during the electrodeposition reaction at the cathode to make the plating film smooth and to have a dense crystal structure.

Such surface improving agents are preferably nonionic surfactants or mixtures thereof, and specific examples thereof include ethylene glycol, polyethylene glycol, benzoic acid, alkylcresol, thiourea, and imidazole. On the other hand, conventionally, anionic surfactants such as 2-methoxy-1-naphthaldehyde, polyethylene glycol monolauryl ether, and polyimine have been mainly used as surface improving agents, but the use of such anionic surfactants may be possible in the present invention. .

The stress reducing agent is added to prevent the plating film from lifting up. All plating films have some stress when the metal particles are electrodeposited due to defects in the plating structure or disparity of the grain arrangement. In particular, in general nickel plating, such a phenomenon is remarkable. Used. Nickel flash plating, however, is not a big problem even if the plating layer is thin so that a stress reducing agent is not used, but a stress reducing agent is added to increase the ductility of the plating film or the plating film.

As such a stress reducing agent, tridecyloxy poly (ethyleneoxy) ethanol (III), N- (3-hydroxybutylidene-P-sulfanylic acid, diisodecyl phthalate or a mixture thereof, etc. are used.

The surface improving agent and the stress reducing agent are each added in a concentration of 0.1 to 2.0 g / l, preferably 0.5 to 1.0 g / l, in the plating solution. If the content is higher than 2.0 g / l, the plating liquid becomes cloudy due to the excess of organic matter, or the equilibrium of the plating liquid is easily broken, and the plating surface is narrowed in the current range, so that the plating surface becomes black without being plated at both high and low currents. If pits are severely generated and the content is lower than 0.1 g / l, cracks are severely generated due to the stress of the nickel plating layer, and pits are formed.

As described above, conductivity aids, complexing agents, and vacancies are appropriately selected according to the type of nickel salt and added to the nickel flash plating solution. The nickel flash plating solution thus prepared has excellent stability and is not sensitive to impurities for a long time. Even use results in uniform plating. Meanwhile, pH buffers mentioned in the prior art may also be used in nickel flash plating solutions.

Supersaturation Nickel salt Slurry  Plating solution

On the other hand, even when using the improved nickel flash plating solution as described above, insoluble anodes, the pH of the plating solution is gradually lowered with the increase in the use time, the problem remains acidic. Therefore, a supplemental plating solution is required to maintain a constant pH of the plating solution while maintaining the concentration of nickel consumed by supplying the plating solution in use.

As the replenishment plating solution, the nickel flash plating solution having the above-described composition range is used as it is, but the plating solution composition including nickel ions is adjusted, but the pH of the solution is continuously lowered and acidified. This is because hydrogen ions continue to be produced in the anodic reaction. To correct this, the supplement solution must be sufficiently alkaline. Supersaturated slurry nickel plating solutions are specially designed for this purpose. On the other hand, the slurry solution should not be precipitated or solidified as a suspension, and the slurry concentration, particle size, and salt composition should be taken into consideration so that the slurry solution can be easily dissolved in an acidic solution.

Therefore, the preparation of the supersaturated nickel salt slurry requires the preparation of the slurry solution from the completely dissolved nickel solution rather than the addition of the powder of nickel salt.

The supersaturated slurry nickel plating solution is first prepared with a nickel flash plating solution, and then mixed with an aqueous alkali solution of a certain combination such as caustic soda, caustic, sodium carbonate, and calcium carbonate under certain conditions, and then re-added to a nickel salt having a suitable particle size and crystal structure. It is manufactured by a series of processes for precipitation. As for the composition of aqueous alkali solution, caustic soda, caustic caustic, sodium carbonate, and calorie carbonate are each preferably comprised in the ratio of 10: 2: 1: 1. At this time, the nickel salt slurry is prepared as a complex salt mixed with nickel hydroxide, nickel carbonate, and an alkali salt, which is easily dissolved in an acid solution.

The size and shape of the slurry particles have the greatest influence on the stability of the slurry solution. Phase separation of the slurry may occur due to aggregation or precipitation between particles. In order to make the suspension solution without phase separation without using dispersant or other additives, the manufacturing conditions such as temperature, addition rate and stirring of alkaline solution are precisely controlled. As shown in FIG. 1, the size of the slurry particles subjected to a certain manufacturing process was Gaussian in shape with a peak of 5 μm. In the composition of the composite salt, carbonate helps the dissolution of the slurry easily by the generation of carbon dioxide when contacted with an acidic solution.

During the reprecipitation of the nickel salt, the pH of the slurry solution and the distribution of the nickel concentration of the solid and the solution may be adjusted according to the concentration and the amount of the alkaline solution. If there is a lot of solids in the production stock solution, plating operation at a relatively high pH is possible, but there is a problem that the viscosity of the slurry solution rises, and if there is little solids, there is a problem in the restoring ability of the acidic solution. It is adjusted at 1.1 and the pH is prepared at 6.5-7.5.

 Therefore, the multifunctional supersaturated slurry plating solution for nickel flash plating according to the present invention can easily dissolve and dissolve nickel concentration consumed when added to the nickel flash plating solution, suppress acidification of the plating solution, and continue plating for a long time. It can be handled and used like a general solution without physical changes such as recrystallization, precipitation, coagulation and phase separation of the slurry without the use of additives.

≪ Comparative Example 1 &

As Comparative Example 1, when the nickel flash plating was performed by the conventional method, the pH of the plating solution was changed according to the plating time. Plating conditions were adjusted to the nickel adhesion amount 120 mg / m <2>, current efficiency 50%, the metal nickel concentration 30g / l, and the temperature of the plating bath at 55 degreeC.

As shown in the above nickel flash plating, as shown in Figure 2, the initial pH of the plating solution was 3.39, but after 8 hours of operation showed a result of falling to 1.85. This shows that the initial plating solution can adjust the nickel concentration but not the pH of the solution. This is because 50% of the hydrogen ions generated in the anodic reaction are concentrated in the solution under plating conditions in which the current efficiency of the cathode is 50%. Since the pH of the solution and the current efficiency of the cathode correlate with each other, it becomes difficult to maintain the cathode efficiency at 50% when the pH of the solution further drops.

Comparative Example 2

Comparative Example 2 investigated the relationship between the pH of the solution and the current efficiency of the cathode. Nickel flash plating conditions were as shown in <Comparative Example 1>, and the nickel metal concentration was fixed at 30 g / l, nickel deposition amount 120 mg / m 2, and the plating bath temperature was 55 ° C., and the pH of the solution was changed between 1 and 8, The current efficiency was measured and the result is shown in FIG.

As shown in FIG. 3, it can be seen that when the pH of the solution is 2 or less, the current efficiency of the cathode drops sharply, so that it is difficult to maintain the current efficiency more than 50%. Low current efficiency not only increases the loss of electrical energy but also generates a large amount of hydrogen gas at the cathode, which can cause various problems. Therefore, the pH of the nickel flash plating solution should be maintained between 2-5, preferably 2.5-4.5 is most advantageous.

&Lt; Example 1 >

In Example 1, the multifunctional supersaturated slurry plating solution for nickel flash plating of the present invention was investigated as a one-component supplement solution. The plating conditions were adjusted to a nickel deposition amount of 100 mg / m 2 and a temperature of 55 ° C. of the plating bath, and assuming that the current efficiency was 60%, the plating was performed while replenishing the slurry plating solution by the amount consumed in the calculation. The change in the concentration and pH of the plating solution is shown in FIG. 4 during 30 days of continuous plating.

 In FIG. 4, the nickel metal concentration was relatively well adjusted at 30 g / l and the pH was set at 4.0 at the initial drying bath, but started to decrease immediately after the start of plating. Equilibrium was found while replenishing the slurry plating solution and 2.6 is shown on the last day of the test. In other words, even after long-term plating for 30 days under the above conditions, it shows that the concentration and pH of the nickel metal ions can be adjusted well.

&Lt; Example 2 >

Example 2 investigated the cathode current efficiency and the whiteness of the plating surface after zinc electroplating using the deposition amount of nickel as a variable. The plating conditions were fixed at a nickel metal concentration of 30 g / l, pH 3.0, and the temperature of the plating bath at 55 ° C., and the front and rear surfaces of the plated steel were measured to measure the actual adhesion amount and current efficiency of nickel, respectively, and the results are shown in Table 1 below. Nickel deposition amount was calculated by assuming a current efficiency of 60%.

Nickel deposition amount, cathode current efficiency and whiteness after zinc plating Nickel deposition amount
Settings (mg / ㎡) Actual adhesion amount (mg / ㎡) Current efficiency (%) Whiteness Front back side Front back side 50 48 50 58 60 80 100 110 112 66 67 79 200 232 240 70 72 80.5 300 356 393 71 79 79 500 592 593 71 71 80

Example 2 is to see the difference between the current efficiency according to the amount of nickel deposition in the nickel flash plating and the whiteness after galvanizing. The amount of nickel deposition varies depending on the purpose of the steel sheet, such as 30 mg / m 2 to 500 mg / m 2, but most of the nickel deposition is performed at 50 mg / m 2 to 200 mg / m 2. In general, the deposition amount of the plating is determined by the current density, current efficiency and the plating time, but in the case of steel plate plating, the current density and the plating time are related to the speed of the steel sheet. Since the speed of the steel sheet varies depending on the plating equipment, it is convenient to set the amount of metal deposition as a set value at a predetermined current efficiency rather than a current density in order to set the plating amount.

As shown in Table 1, the actual plating amount is higher than the setting value of the plating amount, which indicates that the multifunctional supersaturated slurry plating solution for nickel flash plating of the present invention has a very high current efficiency of 70% or more, and zinc regardless of the plating thickness of nickel. The whiteness after plating is very good at about 80 degrees.

Although specific embodiments of the present invention have been shown and described, the present invention may be variously modified and changed without departing from the spirit of the invention as set forth in the claims below, and this is in the technical field of the present invention. It should be understood that it is self-evident to those of ordinary knowledge.

Claims (14)

A multifunctional supersaturated slurry plating solution for nickel flash plating, characterized in that an alkali salt is added to a nickel flash plating solution to which nickel salts, conductivity aids, complexing agents, and vacancy aids for iron ions are added.
The method according to claim 1,
The alkali salt is caustic soda, caustic caustic, sodium carbonate, calories carbonate is added in a ratio of 10: 2: 1: 1 by weight, the addition amount is added in the range of 30 ~ 60g / L A multifunctional supersaturated slurry plating solution for nickel flash plating.
The method according to claim 1,
The multifunctional supersaturated slurry plating solution for nickel flash plating, wherein the weight ratio of the nickel metal in the slurry and the liquid solution in the solid content is adjusted in the range of 40 to 60:60:40.
The method according to claim 3,
The slurry particles have a Gaussian distribution with a peak of 5 µm, and the multifunctional supersaturated slurry plating solution for nickel flash plating.
The method according to any one of claims 1 to 4,
The complexing agent is prepared by adding any one or a combination of gluconic acid, citric acid, tartaric acid, thiourea, and imidazole, and is added at a concentration of 0.5 to 10 g / l,
The vaccinating agent is prepared by adding any one or a combination of ethyleneimine, sodium gluconate, sodium citrate, and sodium alginate, and added at a concentration of 0.1 to 50 g / l,
The nickel salt is prepared by adding any one or a combination of nickel sulfate, nickel carbonate, nickel sulfamate, nickel acetate, nickel formate, nickel fluoride, and nickel fluoride, and added at a concentration of 10 to 200 g / l,
The conductivity aid is prepared by adding any one or a combination thereof selected from sodium sulfate, ammonium sulfate, sulfamic acid, boric acid, ammonium fluoride, sodium formate, ammonium formate, ammonium phosphate, and potassium sulfate, at a concentration of 10 to 200 g / l. Multifunctional supersaturated slurry plating solution for nickel flash plating, characterized in that it is added. delete delete delete delete delete delete delete delete delete

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