JPS5826431B2 - Aluminum plating method on the surface of ferrous materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for applying aluminum plating to the surface of an iron-based material.

The thermal reactor installed in the exhaust system to remove unburned harmful components contained in the exhaust gas emitted from automobile engines by re-combustion is required to have high-temperature corrosion resistance. As a method for imparting this, it is known to hot-dip plate aluminum on the surface of an iron-based material by immersing the iron-based material in a molten metal made of aluminum or aluminum alloy (for example, Japanese Patent Publication No. 50-36421) reference).

Since the above-mentioned known method uses molten aluminum or aluminum alloy, it requires expensive molten metal equipment, is difficult to handle, and is difficult to control the thickness of the plating layer. .

In addition, as a method of imparting high temperature corrosion resistance to the surface of iron-based materials,
Water-based ceramic binder, aluminum powder, phosphoric acid,
After coating with a suspension containing chromic acid and drying by heating, the exhaust gas is passed through the assembled exhaust gas treatment device, and the remaining oxygen in the exhaust gas combines with aluminum to convert alumina into a main component. Method for manufacturing heat-resistant and corrosion-resistant members for exhaust gas treatment equipment in which a diffusion layer is formed
However, since the surface of the corrosion-resistant member proposed above is coated with porous ceramic, most of the aluminum is oxidized, and therefore the high-temperature corrosion resistance of the aluminum itself is not lost. It is thought that the

The present invention provides a method for plating aluminum on the surface of a ferrous material, which eliminates the drawbacks of the conventional methods described above.

That is, this invention applies aluminum or aluminum alloy powder of 50 to 90% weight to the surface of stainless steel.
Vinyl acetate resin or methacrylate resin 10-50
A method for plating aluminum on the surface of a ferrous material, characterized by applying a coating liquid containing a weight of φ, drying it to form an aluminum-containing resin coating, and then heating it above the melting point of aluminum or aluminum alloy. It is.

In this invention, the coating liquid applied to the stainless steel surface is
It consists of powder of aluminum or aluminum alloy (hereinafter referred to as aluminum-based metal unless otherwise specified), a solvent-soluble synthetic resin, and a solvent for the synthetic resin.

The above-mentioned synthetic resins are selected from those having a high decomposition combustion temperature and a slow combustion rate, and vinyl acetate resins and methacrylate resins are suitable as such synthetic resins.

Solvents for these synthetic resins include acetone, butyl acetate, thinner, and water for aqueous emulsions.

The aluminum-based metal powder blended into the coating liquid is preferably granular and has a particle size of 10 to 500 microns.

If the particle size is less than 10 μm, there is a risk that the entire coating will be oxidized during heating, and if the particle size exceeds 500 μm, aluminum etc. will precipitate during storage of the coating solution, which is undesirable.

The above aluminum alloys include Al-Cr (Cr2~
5%, melting point 800°C), Al-8i (Si5-10,
(melting point: 580°C), and the A1 ratio is 90 weight φ or more.

The ratio of the aluminum-based metal and the synthetic resin contained in the coating liquid is 50-90% by weight for the former and 10-5% by weight for the latter.
0 weight φ.

If the ratio of the former is less than 50 weight φ, it is difficult to obtain a uniform aluminum metal plating layer;
If the weight exceeds the heavy weight type, the amount of synthetic resin as a binder will be reduced, making it difficult to apply the coating liquid.

The amount of solvent in the coating liquid is to adjust the viscosity of the coating liquid so that it can be applied and scraped onto the stainless steel surface. It is set appropriately depending on the coating method, etc.

The amount of coating liquid applied to the stainless steel surface is arbitrarily determined depending on the desired thickness of the aluminum-based plating layer to be formed on the stainless steel surface.

The stainless steel coated with the coating liquid as described above is heated to a temperature that evaporates the solvent in the coating liquid, and a resin coating film containing an aluminum metal is formed on the surface of the stainless steel.

Next, the stainless steel with the resin coating formed on the surface is heated at a temperature higher than the melting point of the aluminum metal, preferably at a temperature in the heating atmosphere that is approximately 100°C or more higher than the melting point, until the aluminum metal is completely melted. .

Due to this heating, the resin in the coating film reacts with oxygen in the air and is decomposed and scattered, but at this time, because the burning rate of the resin is slow, the surrounding oxygen is consumed in the combustion of the resin, creating a neutral or reducing atmosphere around it, which prevents oxidation of aluminum and promotes the diffusion of aluminum into stainless steel.

As a result, the surface of the stainless steel is plated with aluminum metal through the aluminum diffusion layer.

The thickness of this aluminum-based plating layer is determined by the amount of coating liquid applied, as described above.

Next, the effects of the aluminum plating method of the present invention are listed below.

(1) When forming a plating layer, there is little oxidation of the aluminum metal, and a plating layer with excellent high-temperature corrosion resistance can be obtained.

(2) The thickness of the plating layer can be controlled arbitrarily.

(3) A uniform plating layer can be obtained even for objects with complicated shapes.

(4) Expensive molten metal equipment for melting aluminum-based metals is not required, and processing can be performed at low cost.

Example 1 A coating liquid was prepared by mixing and stirring 80 parts by weight of aluminum powder (particle size: 50 μm), 20 parts by weight of vinyl acetate resin, and acetone as a solvent.

This coating liquid was applied to the surface of a stainless steel plate and dried with ordinary mud to evaporate the solvent to form a resin coating film (thickness 100 μm) containing aluminum powder.

The sample on which this resin coating was formed was heated at the edge of the blade from 20°C to 800°C for 2 hours, and the results of the change in weight of the sample at that time are shown in the graphs in Figure 1 and Figure 2.

As shown in this graph, the weight of the sample decreases rapidly from around 250℃, which indicates that the decomposition of the resin is progressing rapidly.As the temperature increases further, the resin decomposes completely and reaches 600℃. Although the weight shows the minimum value, the aluminum is slightly oxidized due to the subsequent heat at the cutting edge, which indicates that the weight increases.

Example 2 Aluminum alloy powder containing 6% Si (particle size 62 μ) 7
A coating liquid was prepared by mixing and stirring 0 parts by weight of meccrylate resin, 30 parts by weight of meccrylate resin, and thinner as a solvent.

After the coating liquid was applied to the surface of a stainless steel plate, the solvent was dried at room temperature and evaporated to form a resin coating film (thickness: 100 μm) containing aluminum alloy powder.

The results of the change in weight of the sample when this sample was heated under the same conditions as in Example 1 are shown in the graph of b in FIG.

In the product obtained by heating in this way, the stainless steel plate and the aluminum alloy powder react metallically, and a uniform aluminum alloy plating layer is formed on the surface.
An aluminum diffusion layer with a thickness of 5 to 10 μm is formed inside it.

Note that the weight change rate of the sample shows almost the same change characteristics as in the case of vinyl acetate in Example 1.

[Brief explanation of drawings]

FIG. 1 is a graph showing the heating temperature increase of the sample and the amount of weight change of the sample in Examples 1 and 2 of the present invention, and FIG. 2 is a graph showing the weight change rate of the sample with respect to the heating temperature rise.

Claims (1)

[Scope of Claims] 1. After applying a coating liquid containing 50 to 90 weight of aluminum or aluminum alloy powder and 10 to sO weight φ of vinyl acetate resin or methacrylate resin to the surface of stainless steel, dry dithialuminum-containing coating is applied. 1. A method for plating aluminum on the surface of a ferrous material, the method comprising forming a resin coating film on the surface of the iron-based material, and then heating the material to a temperature above the melting point of the aluminum or aluminum alloy. 2. The method of aluminum plating on the surface of a ferrous material according to claim 1, wherein the aluminum or aluminum alloy powder has a particle size of 10 to 500 μm. 3 Aluminum alloy is Al-Cr type or Al-8i
A method of aluminum plating on a surface of an iron-based material according to any one of claims 1 to 2, which is a metal-based material.