KR101103844B1 - A plating solution of nickel-cobalt-silicon carbide and a surface treatment method of copper mould for continuous casting of steel using the same - Google Patents

Abstract

The present invention relates to a nickel-cobalt-silicon carbide plating solution and a copper mold surface treatment method for continuous casting of steel using the same. Specifically, nickel sulfamic acid as a nickel salt, sulfamic acid cobalt as a cobalt salt, and 45 to 45 The present invention relates to an electrolytic nickel-cobalt-silicon carbide (Ni-Co-SiC) composite plating solution containing 55 nm nanometer silicon carbide and a plating method using the same.

Nickel-Cobalt-silicon carbide (Ni-Co-SiC) plating solution, composite plating, dispersion plating, Cu mold surface treatment

Description

A-Plating SOLUTION OF NICKEL-COBALT-SILICON CARBIDE AND A SURFACE TREATMENT METHOD OF COPPER MOULD FOR CONTINUOUS CASTING OF STEEL USING THE SAME}

The present invention relates to a nickel-cobalt-silicon carbide plating solution and a copper mold surface treatment method for steel continuous casting using the same, and more particularly, electrolytic nickel-cobalt-silicon carbide (Ni-Co-SiC) having high wear resistance on a copper surface. The present invention relates to a plating solution for complex plating.

Molds used in continuous casting of steel are generally made of copper plates. Since the copper mold itself has low strength, the surface is easily worn due to the high temperature and friction of the molten steel when the molten steel is solidified and moved, and thus, the life of the copper mold is not long. In addition, as the copper or copper alloy is fused and mixed on the surface of the cast product, cracks (star cracks) are generated in the product during radiant heat and rolling, thereby degrading the quality of the product or causing defects.

In order to solve this problem, a method of improving the life of the copper mold by coating a wear-resistant material that is not abrasion well on the surface of the copper plate in contact with the molten steel. In the plating method, a composite layer is generally plated on a copper mold in the order of Cu mold / Ni / Cr or Ni-P / Co / Cr. The reason for the multi-layer plating is because of the adhesion and wear resistance, the function of each layer is as follows, an example of a Ni-P / Co / Cr multilayer film is shown in FIG.

Ni or Ni-P: The coefficient of thermal expansion of Ni and Ni-P is similar to that of copper or copper alloy, showing good adhesion with copper or copper alloy.

Co: The coefficient of thermal expansion of Co has an intermediate value between the coefficients of thermal expansion of Ni-P and Cr, and shows excellent adhesion with both Ni-P and Cr.

Cr: Cr has a higher strength and melting point than Ni and Ni-P, and forms a strong oxide layer, which serves to prevent molten steel splash from sticking.

By using this plating method, defects caused by fusion of copper on the surface of the cast product can be suppressed, thereby improving wear resistance and durability. However, in some cases, peeling occurs due to poor adhesion between the layers, and there is a problem in that the work is complicated, difficult, and short in life because it has to go through several processes.

In particular, hexavalent Cr is generally used as the Cr plating layer formed on the outermost surface to improve abrasion resistance, which is one of the six harmful elements defined in the EU, and therefore, it is urgent to develop alternative materials.

Under this background, the present inventors have developed a plating solution that can replace Ni / Cr and Ni-P / Co / Cr multilayer alloy plating having various problems mentioned above in order to improve wear resistance of the copper mold surface for continuous steel casting. During the research, when using Ni-Co-SiC single layer composite solution in which 45-55 nm nanometer SiC was dispersed in Ni-Co, it is more abrasion resistance than conventional multilayer plating and eco-friendly single layer composite plating can be obtained. Confirmed that the present invention was completed.

An object of the present invention is to provide an environmentally friendly nickel-cobalt-silicon carbide plating solution.

It is still another object of the present invention to provide a copper mold surface treatment method for steel playing, which can easily form a single layer composite plating film and can solve problems of poor adhesion and high cost caused by multilayer plating.

Still another object of the present invention is to provide a copper mold for steel playing having excellent wear resistance.

In order to achieve the above object, the present invention provides a nickel-cobalt-silicon carbide plating solution containing nickel salt, cobalt salt, and silicon carbide, wherein the nickel salt is sulfamine nickel, and the cobalt salt is sulfamic acid. Cobalt, and the silicon carbide provides a nickel-cobalt-silicon carbide plating solution, characterized in that the silicon carbide of the nanometer size of 45 ~ 55 nm.

As used herein, the term "plating solution" refers to an aqueous solution of metal salts used in electroplating, and in particular, the present invention refers to a plating solution for plating the surface of the copper mold to improve wear resistance of the copper mold for continuous casting of steel. .

As used herein, the term "nickel salt" is a material used to plate nickel during electroplating. Nickel is used to stably form a plating on the surface of copper mold because nickel shows excellent adhesion with copper or a copper alloy. do. Representatively, nickel sulfamate is preferable, but is not limited thereto if the material can be plated with nickel by electroplating. For stability of the plating solution and maximum efficiency of nickel plating, it is preferable to use 60% -sulfonic acid nickel at 350 to 550 ml per 1 L of the plating solution.

As used herein, the term "cobalt salt" is a material used to plate cobalt during electroplating. Cobalt is used for physically bonding nickel and cobalt because cobalt shows excellent adhesion to both nickel and silicon carbide. Representatively, cobalt sulfamate is preferable, but is not limited thereto as long as it can be plated by electroplating. In order to obtain a constant amount of cobalt content of 40 to 50% by weight in the plating film, it is preferable to use 60% -cobalt 60 to 80 ml per 1 L of the plating solution.

The term "silicon carbide" used in the present invention is a material represented by the formula SiC, and is used to obtain wear resistance of the plating film. The silicon carbide can completely replace the conventionally used Cr, it is more wear-resistant and environmentally friendly than when using the harmful element Cr. For abrasion resistance of the plating film, it is preferable to use silicon carbide of 45 to 55 nm size, and to maximize the wear resistance of the plating film, it is preferable to use 5 to 50 g per 1 L of the plating solution.

In addition, the present invention may further include boric acid which is a pH adjusting agent for 1 L of the plating solution.

As used herein, the term "pH regulator" means a material used to prevent the pH change of the plating liquid during the plating process. Since the plating is affected by the degree of plating and the thickness of the plating layer by the pH, it is preferable to add a material that can control the pH of the plating liquid. From this point of view, the pH of the plating liquid can be prevented by adding boric acid as a pH adjusting agent to the plating liquid of the present invention. In order to obtain a high quality plating film, boric acid is preferably used in an amount of 20 to 50 g per 1 L of the plating solution.

In addition, the present invention may further include nickel halide as a stress releasing agent for 1 L of the plating solution.

As used herein, the term "stress remover" refers to a material used to minimize the residual stress generated when the plating film is formed on the copper mold. When residual stress occurs, peeling occurs due to poor adhesion of the plating, and it is preferable to further include a stress remover. From this point of view, the plating liquid of the present invention preferably further includes nickel halide, which is a stress releasing agent, preferably nickel bromide or nickel chloride. From the viewpoint of obtaining a high quality plating film and minimizing the residual stress, it is preferable to use 1.0 to 3.0 g of nickel halide per 1 L of the plating liquid.

In addition, the present invention may further include an anionic surfactant and sulfur-based surfactant with respect to 1L of the plating solution.

As used herein, the terms "anionic surfactant" and "sulfur-based surfactant" refer to a substance exhibiting surfactant action by ions dissolved and dissociated in water. When the surfactant is added, it is possible to obtain a high quality plating layer by removing a substance that interferes with the plating existing on the surface of the metal to be plated, to prevent pits generated in the plating film, and to obtain high gloss and high roughness. In view of this, it is preferable that 0.1 to 1 g of the anionic surfactant and the sulfur-based surfactant are added to 1 L of the plating solution.

In still another aspect, the present invention provides a copper mold surface treatment method for steel playing, comprising the step of plating a copper mold using the nickel-cobalt-silicon carbide plating solution according to the present invention. Any plating method is not limited as long as the plating solution according to the present invention can be used. Preferably, nickel to platinum anodes are used, and it is preferable to proceed by adding a current density of 1.0 to 5.0 A / dm ² .

In consideration of the efficiency of the plating, the method is preferably carried out at a pH range of 4.0 to 5.0 and a temperature range of 45 to 55 ℃.

In still another aspect, the present invention provides a copper casting copper mold plated with a nickel-cobalt-silicon carbide plating solution according to the present invention. The copper mold for continuous casting produced is not limited in size, shape, etc., as long as it is plated by the plating solution according to the present invention.

The nickel-cobalt-silicon carbide plating solution according to the present invention can form a plating layer having better wear resistance without using Cr which is conventionally used for wear resistance. This has the following characteristics.

First, since the conventional plating method uses a multi-layer plating film composed of Ni / hexavalent Cr or Ni-P / Co / hexavalent Cr, poor adhesion between each layer and additional processes due to multiple processes (complex machining and cleaning) Work) was necessary, resulting in increased costs and poor interlayer adhesion. However, since the nickel-cobalt-silicon carbide plating solution according to the present invention replaces the multilayer plating film with a single layer of the composite plating film, there is an advantage of overcoming the problems of increased cost and poor adhesion between the conventional methods.

Second, instead of using Cr, which is conventionally used for abrasion resistance, SiC is used to form a composite film in which a high-strength ceramic reinforcement phase is dispersed, thereby exhibiting higher wear resistance than conventional surface treatments. As a result, since the wear resistance of the copper mold for continuous steel casting is increased, the service life is increased, thereby improving the process efficiency of the continuous steel casting.

Third, by replacing hexavalent chromium, one of the six hazardous elements set by the EU, with a monolayer composite film, it has the advantage of being an environmentally friendly process. Plating process is a process that uses a variety of chemicals, not only harmful to the human body during work, but also causes environmental pollution in the process of treating the waste material after plating, because it does not use any conventionally used Cr, It is advantageous from an environmental point of view.

The nickel-cobalt-silicon carbide plating solution according to the present invention can form a single layer composite plating film, which can solve the problem of poor adhesion due to multilayer plating and cost increase due to a complicated process. By forming a composite plating film dispersed therein exhibits excellent wear resistance, it can be usefully used in an environmentally friendly process.

Hereinafter, preferred embodiments of the present invention will be described in order to facilitate understanding of the present invention. However, the following examples are merely provided to more easily understand the present invention, and the contents of the present invention are not limited by the examples.

EXAMPLES Preparation of Nickel-Cobalt-Silicon Carbide Plating Solution According to the Present Invention

The nickel-cobalt-silicon carbide composite plating solution according to the present invention is 500 ml of 60% -nickel sulfamate aqueous solution with nickel salt, 80 ml of 60% -cobalt sulfamate aqueous solution with nickel salt and 45-55 with respect to 1 L of the plating solution. It was prepared by mixing 5 g of silicon carbide of nm size.

In addition, 20 g of boric acid was used for 1 L of the plating solution to prevent pH change during plating, and nickel halide (NiCl ₂ , NiBr _2, etc.) was used as a stress remover to remove residual stress of the plating film. g was added. In addition, 0.5 g and 1 g of an anionic surfactant, sodium lauryl sulfate, and a sulfur-based surfactant, saccharin, were added to prevent pit from being formed and to obtain high gloss and high roughness.

The temperature of the plating liquid was adjusted to 55 ° C, and the pH of the plating liquid was kept constant at 5.0.

Comparative Example: Preparation of Conventional Plating Solution

1. Comparative Example 1

In order to obtain an alloy plating film composed of Ni-Co only, a plating solution of the following composition was prepared.

The nickel-cobalt-silicon carbide composite plating solution was prepared by mixing 500 ml of 60% -nickel sulfamate aqueous solution and 80 ml of 60% -cobalt sulfonic acid aqueous solution with a nickel salt with respect to 1 L of the plating solution.

In addition, 20 g of boric acid was used for 1 L of the plating solution to prevent pH change during plating, and nickel halide (NiCl ₂ , NiBr _2, etc.) was used as a stress remover to remove residual stress of the plating film. g was added. In addition, 0.5 g and 1 g of an anionic surfactant, sodium lauryl sulfate, and a sulfur-based surfactant, saccharin, were added to prevent pit from being formed and to obtain high gloss and high roughness.

The temperature of the plating liquid was adjusted to 55 ° C, and the pH of the plating liquid was kept constant at 5.0.

2. Comparative Example 2

In order to obtain the alloy plating film which consists of Ni-P / Co / Cr, the plating liquid for Cr plating film (Pungsan Co., Ltd.) which the Cr plating film can form was made into the comparative example 2. As shown in FIG.

Experimental Example 1 Comparison of Plating Performance

1. Plating

In order to compare the performance of the plating film using the embodiment of the plating solution according to the present invention and the plating film obtained using Comparative Examples 1 and 2, which are conventionally used plating solutions, the following experiment was carried out.

Plating was performed by the following method using the plating solutions of Examples and Comparative Examples. Example and Comparative Example 1 were plated on the copper surface, Comparative Example 2 was plated on the copper surface plated Ni-P / Co.

1. Degreasing: 40 ~ 50 ℃, 3 ~ 5 minutes

2. Soft etching: 20 ~ 30 ℃, 1 ~ 2 minutes

3. Degreasing: 25 ~ 35 ℃, 1 ~ 3 minutes

4. Plating with the plating solutions of Examples, Comparative Examples 1 and 2

In each step, pure water was removed through two cleaning processes to remove impurities on the surface. Nickel to platinum anodes were used as anodes, and current density was maintained at 1.0 to 5.0 A / dm ² .

2. Comparison of plating performance

The plating performance of the plating film obtained by the plating process was compared as follows.

Plating rate was measured by the film formation rate. In addition, in order to measure the wear resistance of the film, abrasion test was performed by rotating the battery 50,000 times with a load of 1 kg using a grindstone with a Taber Abrasion tester.

The comparison of the plating performance thereof is shown in Table 1 below, which is shown in FIG.

Plating amount Plating speed (㎛ / h) Abrasion Resistance @ 50k @ 1kg (mg) Example 50 32 Comparative Example 1 40 120 Comparative Example 2 4 103

As shown in Table 1, it can be seen that the embodiment according to the present invention has superior plating speed, and in particular, abrasion resistance, as compared with a conventionally used plating solution.

Experimental Example 2 Observation of the Plating Surface

The shape of the Ni-Co-SiC film plated according to the present invention was observed by magnification × 1,000 times using FE-SEM, which is shown in FIG. 3. As shown in FIG. 3, the high-strength silicon carbide powder is evenly distributed throughout the specimen, and as a result, it can be seen that it shows high wear resistance.

1 is an example of a conventional multilayer coating, which is a diagram showing the cross-section of a Ni-P / Co / Cr coating, and the characteristics such as the coefficient of linear expansion and the heat transfer coefficient of each layer.

2 is a view comparing the wear resistance of the plating film prepared by the plating solution of Example, Comparative Example 1 and Comparative Example 2 according to an embodiment of the present invention.

FIG. 3 is a view of a composite plating film plated on a copper base using a nickel-cobalt-silicon carbide plating solution according to one embodiment of the present invention at 1000 × times using FE-SEM.

Claims (9)

In a nickel-cobalt-silicon carbide plating solution containing nickel salt, cobalt salt, and silicon carbide, the nickel salt is sulfamine nickel, the cobalt salt is cobalt sulfamate, and the silicon carbide is 45-55 nm nanometer. A nickel-cobalt-silicon carbide plating solution characterized by being silicon carbide of size. The method according to claim 1, wherein 60 to 50 ml of 60% nickel sulfamate, 60 to 80 ml of 60% cobalt sulfamate, and 5 to 50 g of silicon carbide having a nanometer size of 45 to 55 nm are used per 1 L of the plating solution. Electrolytic nickel-cobalt-silicon carbide plating solution comprising a. The nickel-cobalt-silicon carbide plating solution according to claim 1, further comprising 20 to 50 g of boric acid, which is a pH regulator, per 1 L of the plating solution. The nickel-cobalt-silicon carbide plating liquid according to claim 1, further comprising 1.0 to 3.0 g of nickel halide as a stress releasing agent with respect to 1 L of the plating solution. The nickel-cobalt-silicon carbide plating solution according to claim 4, wherein the nickel halide is NiCl ₂ or NiBr ₂ . The nickel-cobalt-silicon carbide plating solution according to claim 1, further comprising 0.1-1.0 g of anionic surfactant and sulfur-based surfactant, respectively, per 1 L of the plating solution. A copper mold surface treatment method for steel playing comprising the step of plating a copper mold using the nickel-cobalt-silicon carbide plating liquid according to any one of claims 1 to 6. The method of claim 7, wherein the method is performed at a pH range of 4.0 to 5.0 and a temperature range of 45 to 55 ° C. 9. The copper casting copper mold plated with the nickel-cobalt-silicon carbide plating solution according to any one of claims 1 to 6.

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