JPS6027751B2 - Manufacturing method of copper coated stainless steel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a knot coating layer on the surface of austenitic stainless steel.

The object of the present invention is first to obtain an austenitic stainless steel that has good corrosion resistance and adhesion, good solderability, rich color, and good thermal and electrical conductivity.

A further object of the present invention is to improve the following conventional method of applying a copper coating to austenitic stainless steel.

Conventionally, known methods for coating stainless steel with copper include electroplating, electroless chemical plating, vacuum plating, and compression.

However, with the electroplating method and electroless chemical plating method, it is difficult to obtain a plating that has both corrosion resistance and adhesion, and with the vacuum plating method, the equipment cost increases and it is difficult to obtain a large plated product. is difficult. Also, the compression method is
Because products are made by punching or cutting the clad material, the stainless steel base is exposed on the punched surface, making it impossible to obtain products that require copper coating on the entire surface, and products obtained by the pressure bushing method. There are also limits to the shape of or,
Conventionally, as a method for coating austenitic stainless steel with copper, Japanese Patent Publication No. 45-113687 ``Method for heat treatment of copper-plated austenitic stainless steel sheet'' is known.

In this method, a copper-plated austenitic stainless steel plate is heated to a temperature of 1,090 to 1,120 in a non-oxidizing atmosphere.
The invention is characterized in that an alloy layer is formed between the copper plating layer and the stainless steel sheet base by performing bright annealing for a short time in a temperature range of 0.00°C. but,
In this method, since processing is performed after plating, the stainless steel base is exposed at the cut surface, etc., and it is not possible to obtain a product that requires copper coating on the entire surface, similar to the pressure bushing method described above. In addition, conventionally, as a method for manufacturing coated steel, U.S. Patent No. 3,311,
No. 493 ``Process for manufacturing copper-coated steel'' is known.

This method involves coating an iron-based metal surface with a mixture of 2 to 1 weight percent cuprous oxide and the balance cuprous chloride;
, 100 qo within 1 minute in a hydrogen atmosphere, and then rapidly cooled to 700 oo or less to form a copper coating with adhesive strength and corrosion resistance on at least one side with a thickness of 7.5 qo or more. In this method, the copper compound is reduced at a high temperature of 1,100° C. in a hydrogen atmosphere, and the copper is precipitated and melted to diffuse into the base material. However, since the heating is carried out in a hydrogen atmosphere and the heating is carried out in two or three stages, the disadvantage is that the equipment becomes large and the thermal energy increases. Moreover, unlike the conventional method, a steel coating method is also known in which the base material is not stainless steel but aluminum.

For example, there is Taruko Sho 43-8161, ``Method of forming an alloy layer without pinholes on a base material made of aluminum or aluminum alloy.'' This method consists of ``a first step in which a sticky hydrocarbon is applied thinly to the surface of the base material, aluminum or aluminum alloy, and a fine metal halide powder is applied to the surface of the material after the first step. It is characterized by the combination of a second step of spraying and adhering the material, and a third step of heating the product after the second step to a temperature above which the sublimation phenomenon of the halogen halogen occurs in a furnace, and then dissipating the heat. . The technical concept is to attach cuprous chloride in a solid state to the surface of the aluminum base material, then heat it in the air to cause a substitution reaction, causing the copper to diffuse into the aluminum base material and form an alloy layer. The purpose is to form a copper coating layer with good adhesion. However, when the present inventors tried to apply the technical idea described herein to a case where austenitic stainless steel is used as the base material, it was not possible to obtain a steel coating with good adhesion. As a result of various studies, we have discovered that a copper coating layer with good adhesion can be obtained by subjecting austenitic stainless steel to a substitution reaction with copper chloride in a non-oxidizing atmosphere.

The present invention has been made based on this discovery. That is, the gist thereof is a method for producing copper-coated stainless steel, which is characterized in that chlorinated steel is attached to the surface of austenitic stainless steel and then heated to 450 to 700°C in a non-oxidizing atmosphere. It is. The base material in the present invention is austenitic stainless steel.

In addition, the base material is not limited to steel, it may also be a semi-finished product made by processing the steel, and it is not limited to the entire surface of the base material or semi-finished product, but may be only a portion thereof depending on the use of the product. The method of the present invention may be applied to. Further, as a method for depositing copper chloride in the method of the present invention, the following method can be used.

■ A method in which a thin layer of chlorinated steel is deposited on the surface of the base material by sinking it into a molten chlorinated steel plate and then pulling it up. ■ A method of kneading chlorinated steel with alcohol to form a paste and applying this.

■ A method in which a sticky hydrocarbon or alicyclic alcohol is applied thinly to the surface of the base material, and chlorinated steel powder is spread and adhered to the surface.

■ A method in which chlorinated steel powder is kneaded with solid paraffin and then heated and applied after being stored in a solidified state.

■ A method of applying a liquid in which chlorinated steel powder is dispersed in a dispersion consisting of a hydrophobic solvent and an aliphatic nonpolar polymer.

The heating temperature range in the method of the present invention is 45 to 0 or higher, at which the substitution reaction between the base metal and copper occurs, and the maximum temperature is 70 to 0.
That's it.

It has been confirmed through experiments that when the temperature exceeds 70 picoC, the adhesion deteriorates. The details of the experiment will be explained next.

50 x 50 x 1 piece of austenitic stainless steel (
JISSUS 304) was used as a base material, and the base material was washed with a normal sulfuric acid aqueous solution, taken out, and dried.

After applying a thin layer of vaseline to the surface of the pretreated base metal, fine crystal powder of No. 1 steel chloride is spread and adhered to the surface, and then
Tilt the base material to remove excess cuprous chloride crystal fine powder,
Next, the base material was held in a non-oxidizing atmosphere purged with argon gas and in a furnace at a temperature of 450 to 75 psi for 5 minutes each. Thereafter, this was taken out, the base material was cooled to room temperature, and the remaining surface material was removed by washing with water. Electrical steel plating was applied to the base material to a thickness of 20 mm. The base material was held in a furnace at 300° C. for 40 minutes, and then cooled with water. The number of blisters in the steel coating layer of each base material was investigated. The results are shown in FIG. In Figure 1, the horizontal axis shows the heating temperature when coating copper, and the vertical axis shows the number of blisters that occur on one surface of the base metal. It can be seen that the number of From this, the maximum heating temperature in the method of the present invention is set at 70°C.
It was set at 0qo. Further, the atmosphere in the method of the present invention may be a rare gas such as argon or nitrogen gas as long as it is a non-oxidizing atmosphere. After adhering chloride steel to austenitic stainless steel, it is not possible to obtain a copper coating layer with good adhesion as described above by heating in the air, and the melting point of copper is This differs from those that require more heating. Moreover, in the method of the present invention,
The heated base material is taken out of the furnace, washed with water, or washed with a brush to remove any remaining residue with a brush.

According to the method of the present invention, unlike conventional electroplating methods, copper-coated steel having both corrosion resistance and adhesion can be obtained.

Furthermore, unlike conventional vacuum plating methods, equipment costs are not high, and even large copper-coated products can be easily obtained.
Furthermore, unlike the conventional Ujiyabu method, the entire surface of an already molded product can be coated with copper, and the product can also be made into an arbitrary shape. Furthermore, according to the method of the present invention, since the substitution reaction can occur in a non-oxidizing atmosphere, a copper coating layer with good corrosion resistance can be obtained for austenitic stainless steel.

It has been recognized since ancient times that copper has extremely excellent corrosion resistance, and even when exposed to the atmosphere for long periods of time, its surface exhibits a beautiful patina and corrosion does not progress inside. By imparting this excellent function to the surface of austenitic stainless steel, we can obtain a product that maintains the mechanical strength of austenitic stainless steel and exhibits outstanding corrosion resistance even in environments where the stainless steel corrodes. be able to. The content of the experiment regarding this corrosion resistance will be explained next. A 50 x 50 x 1 side austenitic stainless steel piece (JISSUS304) is used as the base material,
Approximately 3 layers of copper coating are applied to the surface in the same manner as described above,
Furthermore, the corrosion resistance of the base material, which was coated with electrolytic copper glazing 20 times in the same manner as described above, was investigated.

The corrosion resistance test was conducted by subjecting the base material to salt water spray for 120 hours continuously. The results are shown in FIG. Second
In the figure, the horizontal axis shows the heating temperature when coating the steel, and the vertical axis shows the number of blisters and pinholes that occurred on one surface of the base material, and the heating temperature ranges from 450 to 700 qo. It can be seen that the number of blisters and pinholes is small and does not differ greatly within the range. The results of this experiment confirmed that the austenitic stainless steel having a copper coating layer obtained by the method of the present invention has corrosion resistance that can be used as a material for coastal roofs exposed to sea breeze. Furthermore, when the method of the present invention is applied not to the entire surface of austenitic stainless steel but only to one part thereof, there is a potential difference at the boundary between the part where the stainless steel base is directly exposed on the surface and the copper coated part. Since the amount is small, corrosion due to local battery action hardly occurs.

Therefore, the method of the present invention can also produce partially coated products having copper properties and stainless steel properties in each part, depending on the intended use of the product. The thickness of the copper coating layer obtained by the method of the present invention is about 3 mm, but copper, chrome,
A copper coating layer with good adhesion can be provided as a base material for electroplating of nickel or the like. Furthermore, the austenitic stainless steel coated by the method of the present invention brings good news regarding bondability, which is one of the deficiencies of stainless steel.

In other words, soldering is used as a simple method for joining stainless steel, but in the past, the passive film covering the stainless steel had poor solder wetting properties, and the base surface was not clean. However, it was also extremely difficult to solder. However, with stainless steel coated with copper by the method of the present invention, when soldering is performed through the copper coating layer, the wetting properties of the solder are extremely good, the bonding work can be significantly simplified, and the soldering process can be performed quickly. work is possible, the bonding strength is high, and both bonding materials can be completely bonded. Also, compared to copper, austenitic stainless steel has a thermal conductivity of about 1/2 and an electrical conductivity of about 1/5, which is lower than that of copper.Furthermore, the surface of austenitic stainless steel is covered with an oxide film, making it difficult to contact. It is known that resistance is also large. However, stainless steel coated with copper by the method of the present invention also has the characteristics of the above-mentioned steel, and has increased thermal conductivity and electrical conductivity, and is improved to have a low contact resistance. . Therefore,
The copper-coated steel obtained by the method of the invention can be used in heat transfer materials and electrical materials. Further, in the method of the present invention, heating may be performed in a non-oxidizing atmosphere instead of in a hydrogen atmosphere as in the method for producing copper-coated steel of the above-mentioned US patent.

That is, in the method of the present invention, not only does it not require hydrogen to cause a reduction effect, but the gas is also easy to handle and is not dangerous. In addition, the method of the present invention requires only one heating, compared to the manufacturing method disclosed in the above-mentioned U.S. patent.
Unlike the technique in the publication and the manufacturing method in the US patent, it can be processed at low temperatures, resulting in energy savings and improved economic efficiency.

The products obtained by the method of the present invention can be used for roofs,
Used for many purposes such as building materials such as panels, pots and pots and other pottery equipment, equipment and parts materials for various industries such as the petroleum industry and synthetic chemical industry, electrical and electronic parts, heat exchangers, interior decorations, works of art, etc. In addition, the lubrication effect of coated steel can be used to improve the workability of stainless steel.

Next, the method of the present invention will be explained with reference to its first and second embodiments.

First Example 50x50x1 side austenitic stainless steel piece (
JISSUS 304) was used as a base material, and the base material was soaked in ordinary nitric-fluoric acid solution, and then taken out, washed with water, and dried.

After applying a thin layer of Vaseline to the surface of the mother village that has been pretreated, fine crystal powder of oxidized No. 1 is spread and adhered to the surface.
Remove excess chloride from the base material or by blowing air.
The copper crystal fine powder was removed, and then the mother village was held in a non-oxidizing atmosphere purged with argon gas and in a furnace at 500° C. for 5 minutes. Thereafter, this was taken out, and after the base material was cooled to room temperature, the residual liquid on the surface was removed by washing with water. As a result, an austenitic stainless steel whose surface was covered with a steel coating layer of approximately 3 mm without any pinholes was obtained. FIG. 3 is a microscopic photograph of a cross section of a steel piece obtained by the method of this embodiment, and this photograph shows that the copper coating layer 2 is
It can be clearly seen that it is uniformly formed on the surface. The copper-coated stainless steel piece obtained as described above and the one with a patina on its surface have the metallic luster of conventional stainless steel and the copper color and patina that could not be achieved sufficiently with colored stainless steel. This made it possible to produce a rich variety of colors for stainless steel products. In addition, when copper wire was soldered to the copper-coated stainless steel piece obtained as described above using spear soldering (JISC2512), which is commonly used for soldering electrical equipment, good soldering was obtained. showed his sexuality.

Second Example 50x50x1 piece of austenitic stainless steel (
JISSUS 317) was used as a base material, and the surface of the base material was polished, washed with a sulfuric acid aqueous solution, and then taken out and dried.

A coating solution prepared by adding cuprous chloride to a dispersion of hydrophobic solvent trichloroethane and polybutene with a molecular weight of 2,500 was uniformly applied to the surface of the pretreated base material at a rate of 200 cc/cm, and after air-drying, After being kept in a 600° C. furnace purged with nitrogen gas for 4 minutes, it was taken out and washed with water. As a result, an austenitic stainless steel covered with about 3 layers of copper coating was obtained as in the case of the first embodiment. The thus obtained copper-coated steel piece was plated with 20 μm of conventional electrical steel.

The base material was held in a furnace at 300° C. for 4 minutes and then cooled with water. The coating layer was examined, but no blisters were found.
In addition, salt water mist was applied to the steel coated steel piece for 12 consecutive hours and the surface was examined, but no blisters or pinholes were observed. The method of the present invention is not limited to the above embodiments, and additions and changes can be made as long as they do not go against the gist of the claims of the present application.

[Brief explanation of drawings]

The drawings relate to a steel piece obtained by the method of the present invention; FIG. 1 is a graph showing the results of an adhesion test, FIG. 2 is a graph showing the results of a corrosion resistance test, and FIG. 3 is a micrograph. 1: Base material, 2: Steel coating layer, 3: Silver coating layer for microscopic observation. Figure 3 Figure 1 Figure 2

Claims (1)

[Claims] 1. A method for forming a copper coating layer on the surface of austenitic stainless steel, which comprises depositing copper chloride on the surface of the steel and then heating it to 450 to 700°C in a non-oxidizing atmosphere. Method of manufacturing coated stainless steel.