JPH0355545B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention provides a coating film consisting of a high-molecular organic compound having special properties and an aluminum paste for paint dispersed therein, which has a coating film that is made of a polymeric organic compound having special properties and an aluminum paste for paints that is below the melting point of aluminum (approximately
A new type of copper whose surface has been modified and strengthened by a new method of forming an aluminum-copper alloy on the surface of copper and copper alloy by utilizing the previously unknown properties exhibited when rapidly heated to temperatures above 660°C. The purpose is to provide alloy-based industrial materials.

[Prior Art] In order to form an alloy layer on the surface of a certain base metal, the following methods are mainly used: () Contacting the surface of the metal with a molten liquid of another metal; () Pressing or plating the other metal. This method is based on one of the following methods: heating and diffusing other metals onto the surface of the base metal; and (2) fixing and diffusing the vapor or ions of the other metal onto the surface of the base metal in a sealed container.

In the case of aluminum, the metal itself is extremely easily oxidized and its surface is always covered with an oxide film, making the crimping incomplete.Also, aluminum is electrically extremely base, so it cannot be used in aqueous solutions. Since electroplating is not possible with non-aqueous solutions or low melting point molten salts, but it has not yet been applied industrially, the () method has not been put into practical use, and is mainly used to deposit the base metal into a molten aluminum liquid bath. The aluminum layer sprayed by the () method and () method by dipping or the thermal spraying method is heated to 800℃.
A method has been implemented in which the lower layer is melted and diffused by heating to a higher level.

However, all of these require large-scale and expensive equipment.
It requires high operating costs and complicated and precise work management, and cannot be said to be a method that can be easily implemented depending on the size of the company.

On the other hand, copper-aluminum alloys have unique and excellent performance as so-called aluminum bronze, but those with a third component added thereto exhibit even more excellent properties and have a wide range of uses. However, this type of alloy is often difficult to process or cast, and its improvement is one of the challenges in the metal material manufacturing industry. If an alloy layer containing an aluminum component and having a desired structure can be obtained by simple means on the surface of a copper-based metal containing other necessary components, the industrial effects would be extremely large, but the above-mentioned technical problems would not be possible. This has become difficult to implement for several reasons.

[Problems to be Solved by the Present Invention] In order to add and diffuse aluminum components onto the surface of copper and copper-based alloys, which has conventionally been impossible to do simply, the inventors have found that: (2) Melting the aluminum in a reducing atmosphere; (3) Removing the oxide film on the surface of the copper or copper alloy. (4) Furthermore, since aluminum and copper are extremely susceptible to oxidation, especially at high temperatures, (2) and (3) are carried out at the same time. We assumed that the above four points had to be solved.

[Means for Solving the Problems] The inventors solved the above four points, which at first glance seemed to be extremely difficult to realize, by discovering and confirming the following facts.

That is, one of the inventors of the present invention, while researching a heat-resistant paint based on a new concept, developed a stock solution in which an aluminum paste for paint was added to an organic solvent solution of a film-forming organic polymer compound having a specific chemical structure or an aqueous emulsion thereof. was applied onto a polished copper plate, air-dried at room temperature, and then heated in an electric furnace at 700-800°C.
When heated to a temperature of I confirmed a new fact that was missing.

The inventor understood this new fact as follows:
That is, currently commercially available aluminum pastes for paints are produced by grinding metallic aluminum powder or foil with stearic acid and mineral spirits (petroleum components with a boiling point of 140 to 180°C) in a ball mill or stamp mill, as is well known in the industry. Crush and manufacture. Aluminum is naturally very susceptible to oxidation, so a fresh metal surface produced by grinding in a mill should immediately be completely covered with an oxide film, but in this case, at the same time as it is produced, the coexisting Encased in stearic acid and mineral spirits, it is preserved fresh in commercial pastes. This is clear from the fact that if a commercially available aluminum paste for paint is treated with a hydrophilic organic solvent that dissolves stearic acid and mineral spirits and then immediately poured into water, it will react with water while generating heat and generate hydrogen gas. It is. Next, the surface of the fresh aluminum particles blended as a paste in the resin solution is protected by being wrapped in a resin layer even during dry coating, but the resin layer is heated above the thermal decomposition point of the blended resin. is exposed to the outside world for the first time at the moment it is thermally decomposed. However, at that time, it was not oxidized immediately due to the reducing resin decomposition gas that filled the surrounding area.
It is presumed that the polished surface came into direct contact with the base metal surface, which had also been kept fresh, forming an alloy and fixing it.

The most necessary condition in this case is the absence of foreign matter between the two metal surfaces. This became clear from the fact that it was not formed uniformly.

In the paint industry to which the inventor belongs, the above-mentioned aluminum paste for paints has been improved through many years of research, and due to its excellent hiding power, it is often used in paints, especially for silver painting on metal surfaces. However, as can be seen from the fact that heating with a torch lamp is the standard method for peeling off this so-called "silver pen", the above characteristics of aluminum paste for paint and heating at high temperatures have not been recognized at all in the past. .

However, in order for the aluminum in this paint aluminum paste to form a uniform alloy layer with the base metal surface at 700 to 800°C, the selection of the organic polymer compound that coexists with the aluminum was extremely important. The most important point is that they disappear virtually completely during thermal decomposition, and the inventors have investigated a number of film-forming organic polymer compounds, particularly by analyzing their thermal analysis curves (TGA) in a nitrogen stream. (curve) to select compounds in which 95% or more of each compound decomposed and disappeared in its decomposition temperature range. As a result, the following organic polymer compounds were selected as suitable for the purpose of the present invention: (a) methyl, ethyl, isopropyl, n-butyl, 2-ethylhexyl acrylate; 2-hydroxyethyl-, hydroxypropyl-ester, methyl methacrylate,
Ethyl, isopropyl, n-butyl, n
A polymer of one compound selected from esters of acrylic acid and methacrylic acid, such as -hexyl-, lauryl-2-hydroxyethyl-, and hydroxypropyl-ester, or a polymer of two or more compounds. Copolymer of (350
~450°C) and (b) alkylated modified melamine resin (400°C).

Each of the above organic polymer compounds is soluble in one or a mixture of solvents such as alcohols, ketones, esters, cellosolves, carbitols, dimethylformamide, dimethylacetamide, dimethylsulfoxide, etc. After the solvent evaporates, the solution forms a film on the surface of the metal, is thermally decomposed at the temperature ( ) above, and substantially disappears from the coating system. On the other hand, polyvinyl chloride, which is also soluble in organic solvents and has film-forming properties, epoxy resins that do not contain urethane bonds, and cellulose resins lose 20 to 65% of
When heated in air, oxidative combustion occurs and the residual amount decreases, but it does not completely burn, especially in the coating where heat-resistant materials coexist, and a considerable amount of carbon and other components remain. It is unsuitable as a material for implementing the present invention.

To further explain the above new facts, when the above resin is rapidly heated on the surface of copper or copper-based alloy at 700-800℃, which is above the thermal decomposition point of the resin, the reducing power of the decomposed gas increases significantly. It was newly confirmed that this method not only prevents the oxidation of the aluminum melt in the atmosphere, but also reduces the oxide film on the surface of the copper or copper alloy that comes into contact with it. In other words, it was discovered that the above-mentioned resins selected by the inventors have a so-called "flux" effect that removes the oxide film on the surface of copper-based metals by rapid heating at 700 to 800 degrees Celsius. That's what I did.

It is well known that in addition to inorganic compounds such as zinc chloride and borax, organic compounds such as rosin and abietic acid, which is the main component, are used as fluxes for copper-based metals, but they are mainly used as resins for paints. In the above organic polymer compound,
It was completely unknown that there is a flux effect on at least copper or copper-based alloys at 700-800°C.

That is, a coating film is formed on a copper or copper-based alloy surface using a coating liquid that is a mixture of aluminum paste for paint and a solution of a resin selected by the inventor according to specific standards (first step); Rapidly heat this to 700-800℃
If the aluminum is melted and the specific resin is thermally decomposed at the same time, the specific properties of both components will be combined (second step). As a result, the above-mentioned four conditions, which were thought to be almost impossible to realize, were satisfied, and the method of the present invention for forming an aluminum-copper alloy on the surface of copper or a copper alloy has been achieved as intended. It is something that

[Operations and Effects of the Invention] The operations and main effects of the present invention on the copper-based metal materials and equipment manufacturing industry are as follows: (1) Raw materials or products having an aluminum-bronze alloy layer can be After manufacturing using a copper alloy that does not contain copper or aluminum or contains a small amount of copper or aluminum, which is easy to process or cast, the aluminum component is additionally diffused from the surface, and the surface is not exposed to external mechanical or chemical A raw material or a finished product is obtained with a damage-resistant aluminum-bronze alloy layer.

(2) The equipment required for this is a coating equipment for general metal paints, a drying equipment, and a maximum temperature of 800℃ according to the scale of operation.
An open heating furnace and waste gas treatment equipment are sufficient, and products with high performance can be manufactured economically with extremely simple operations.

(3) The coating liquid used in the first step of the present invention contains a solvent that dissolves and floats rolling oil used in cold rolling or rust preventive oil. No particularly rigorous pretreatment of the copper or copper-based alloy surface is required prior to the process. There is a great benefit in that the strict pretreatment steps such as degreasing, cleaning, and polishing, which are generally essential in the case of surface alloying treatment, are omitted.

(4) The first step of the first process of the present invention is carried out using a special coating liquid that has almost the same coating properties as general metal coatings, so the coating method and the size and shape of the raw materials to be coated are is completely free.

(5) The coating film obtained in the first step has sufficient flexibility, so it can be easily painted after painting.
After freely winding, bending, and other shaping, it is possible to move on to the second process.

(6) The superiority of the formed aluminum-bronze alloy layer is well known, so it will be omitted here, but by the method of the present invention, a thin aluminum-bronze coating can be formed on the surface of a brass raw material or a molded product. Ba,
"Dezincification phenomenon" that is difficult to avoid during subsequent heat processing
It is worth mentioning that it can prevent discoloration, deformation or deterioration of surface properties of products due to

Some examples are listed below to specifically illustrate the embodiments of the present invention, but the materials, quantities, or embodiments disclosed below are not intended to be limiting in any way. "Parts" shown in the examples are parts by weight unless otherwise specified.

Example 1 Methacrylic acid resin stock solution (heating residue 60%) 58
Coating liquid for forming aluminum alloys, which is a uniform mixture of 36 parts of n-butylated modified melamine resin stock solution (heating residue: 60%), 328 parts of ethyl cellosolve, and 324 parts of aluminum paste for paint (heating residue: 65%). ”
was applied onto the above-mentioned "treated copper plate for test" by the overlay coating method and air-dried at room temperature. 750 for the same item
When heated for 30 minutes in an electric furnace at 700°C, taken out, allowed to cool, and polished in water with the nylon polishing cloth, a slightly blackish brass-colored alloy layer appears, and this alloy layer is subsequently heated at 700°C. Even after heating for 30 minutes, the color only slightly darkened. Further, the same surface was polished with a commercially available liquid metal polishing agent [Picard Metal Polishing, manufactured by Nippon Hiryo Kogyo Co., Ltd.] to obtain a golden glossy surface. In addition, after cleaning the brass-colored alloy surface obtained by processing in exactly the same manner as in this example with the above-mentioned "copper surface cleaning liquid", the above-mentioned "coating liquid for aluminum alloy formation" was applied again, and after air drying at room temperature, It was heated for 30 minutes in an electric furnace at 750°C. When this was taken out, left to cool, and polished with the nylon polishing cloth, a brass-colored alloy surface was obtained again, and at the same time, the thickness of the alloy layer increased slightly.

Example 2 When a "test treated copper plate" on which aluminum bronze layers were formed on both sides by the same process as in Example 1 was heated in an electric furnace at 750°C for 115 hours, no aluminum bronze was formed. The remaining part was completely oxidized and disintegrated, whereas the aluminum bronze forming part remained completely with only a browned surface.When this was strongly polished with #250 carborundum abrasive paper, it was found that the hardness was significantly higher than that of pure copper. , resulting in a bright surface with a slightly reddish aluminum bronze layer.

Example 3 Methacrylic acid resin stock solution (heated residue 60%) 110
A dispersion of 60 parts of n-butylated modified melamine resin stock solution (heating residue: 60%), 870 parts of ethyl cellosolve, and 560 parts of aluminum paste for paint (heating residue: 65%) was subjected to "test treatment". "Copper original plate"
I brushed it on. After drying the same product at room temperature, 800℃
When heated for 30 minutes in an electric furnace, taken out, and allowed to cool, the entire surface was covered with a gray film, but when this was polished in water with the nylon abrasive, the black surface obtained was
It had a hardness that could hardly be polished by #250 carborundum abrasive paper, and it did not discolor or peel off even when heated in a furnace at 800°C for 2 hours, showing high high-temperature oxidation resistance.

Example 4 95/ with precise characters and patterns engraved on its surface
The surface of a medal made of 5-brass (alloy of 95:zinc 5) was washed with the above-mentioned "copper surface cleaning solution", washed with water, and dried. ” was applied by dip coating method.
After forcing the same product to dry with warm air, heating it in an electric furnace at 800°C for 30 minutes, taking it out, and leaving it to cool, the surface turned brownish black, but this was removed with the nylon polishing cloth in water. When polished, a brass color appeared, and when it was further polished with the commercially available liquid polishing agent, it became a beautiful metallic luster of aluminum bronze. Moreover, the precise characters and patterns on the same surface retain their original shape, indicating that the alloy formation of the present invention proceeds completely uniformly. It turned out that it can be applied to Note that even when the aluminum bronze surface obtained here was heated in an electric furnace at 600°C for 15 hours, it only slightly browned, and by light polishing with an abrasive, it regained its beautiful metallic luster. Furthermore, when the operation of this example was repeated on the aluminum bronze surface polished to a metallic luster, the color tone of the surface gradually increased in whiteness, and an increase in the aluminum content in the surface alloy layer was observed.

Example 5 60/40 brass (copper) with a thickness of 0.8 mm and a total surface area of 52 cm ²
A 60:zinc 40 alloy) plate was washed with the above-mentioned "copper surface cleaning solution," rinsed with water, and dried, and then the same "coating solution for forming an aluminum alloy" as used in Example 1 was brushed onto the entire surface. After drying the same product naturally at room temperature, 800℃
Heat in an electric furnace for 30 minutes, remove and leave at room temperature (28℃).
After being allowed to cool to 100%, the surface was polished with the nylon polishing cloth in water, washed again with the "copper surface cleaning solution", rinsed with water, and dried. The surface returned to a brass-colored metallic luster, but the 60/40 brass original plate It was slightly more reddish. This was used as the sample (A). Next, the sample (A)
A 60/40 brass plate of exactly the same quality, shape, and size as the original plate was also cleaned with the above-mentioned copper surface cleaning solution, rinsed with water, and dried as a sample (B). Sample (Part A)
and (B) at the same time in an electric furnace at 800℃ for 2 hours, then taken out and left to cool to room temperature (28℃). - (A), (B)' - (B) ratio is sample (A)
100, that of sample (B) was 255.Subsequently, samples (A)' and (B)' were immersed in the above-mentioned "copper surface cleaning solution" for the same amount of time, and then washed and dried. If A)'' and sample (Otsu)'', the ratio of weight loss (A)' - (A)'', (Otsu)' - (Otsu)'' is 100:
3590, and the dimensions of (B)'' were clearly larger than those of (B), and the ratio (B)''/(B) was approximately 102% in both length and width. This result clearly shows that an aluminum-bronze alloy was formed on the surface of the sample (A), and its high-temperature oxidation resistance was significantly improved. (B)) As a characteristic of brass with a composition of 60% copper and 40% zinc, it appears that the weight increase due to oxidation during heating is relatively small. This clearly shows that dezincing and subscale formation occurred due to the extremely high temperature heating of the raw material, and that the surface layer and the metallurgical structure of the substance were significantly altered.

The effect of preventing dezincification during heat processing of brass and suppressing changes in product dimensions caused by dezincing by the surface coating of a thin film of aluminum bronze can be achieved by applying the present invention to the surface of brass castings for ships. This shows the expected effect of suppressing cavitation erosion as well as the possibility of industrial application of the method of the present invention.

Claims (1)

[Scope of Claims] 1 (a) A mixture of a polyacrylic acid ester resin and an alkylated modified melamine resin, a polymethacrylic acid ester resin and an alkylated modified melamine resin, which can be substantially decomposed and disappeared by heating. A dispersion containing an aluminum paste for paint and a polymer compound selected from the group consisting of a mixture with a resin and a mixture of a polyacrylic acid ester-polymethacrylic acid ester copolymer and an alkylated modified melamine resin is prepared using copper or copper. A first step of coating the alloy material surface to form a primary coating film; (b) A second step of heating this to 700 to 800°C to form an aluminum-copper alloy on the copper or copper alloy material surface. A method for forming an aluminum-copper alloy layer comprising two steps.