JPH0420979B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention involves thermally spraying metal, ceramics, or a composite powder thereof onto the surface of a base material such as metal or ceramics, applying ladder silicone dissolved in a solvent to the surface of this thermally sprayed coating, and curing it. The present invention relates to a surface treatment method for a thermal spray coating, characterized by the following.

Boards made from metals, ceramics, etc.
It is sprayed onto the surface of base materials such as rods and various molded products to improve heat resistance, corrosion resistance, and aesthetic appearance.

The base materials used are metals such as aluminum, iron, copper, and stainless steel, and ceramic products such as ceramics, sintered ceramics, and glass.The powders to be thermally sprayed are metal powders and wires such as titanium, stainless steel, nickel, and aluminum. Powders of high melting point inorganic compounds such as titanium oxide, aluminum oxide, zirconium oxide, silicon carbide, silicon nitride, and composites thereof are used.

Thermal spraying is an effective and widely used means of coating and protecting the surfaces of metal and ceramic products, but on the other hand, the surfaces are porous and will absorb moisture if left in contact with water or moisture for a long time. There is a drawback.

A method often used to prevent this drawback is to apply a solution of an organic polymer to the sprayed surface. Phenol resin, epoxy resin,
By applying a solution of an organic polymer such as nylon resin or polyimide resin, a tough film is formed on the surface to prevent the thermal sprayed film from absorbing moisture due to its pores. However, organic polymers inherently have low heat resistance, and even those with high heat resistance begin to carbonize at 400°C, which is undesirable because the thermal spray coating loses its high heat resistance characteristic.

The solvent-soluble ladder silicone used in the present invention is commonly called glass resin, and is a silicone oligomer in which Si and O are bonded in a lattice pattern in the molecule, and the terminal has an alkoxy or phenoxy structure. Commercially available products include Glass resin from Owens-Illinois.
Resin) etc.

This ladder silicone is dissolved in a solvent and applied, and after the solvent is evaporated, crosslinking occurs when heated to 100 to 400°C, increasing heat resistance and solvent resistance. At this time, by using an acidic catalyst in combination, the heating temperature can be lowered and the heating time can be shortened. As a result of experiments, it was found that ladder silicone has particularly good adhesion to thermally sprayed surfaces compared to organic polymers, and provides sufficient durability, weather resistance, water resistance, moisture resistance, etc. when applied to thermally sprayed surfaces.

To carry out the present invention, first, a metal as a base material,
Thermal spraying is performed on materials such as ceramics and products using metal powder, wire rods, ceramic powder, etc.

The particle size of the powder is between 100 microns and 5 microns, preferably between 50 microns and 10 microns. For thermal spraying, a commonly used plasma spraying method is used. As the thermal spraying material, aluminum, titanium, zinc, chromium, tantalum, nickel, etc. or alloys thereof, zirconium oxide, aluminum oxide, titanium oxide, silicon carbide, silicon nitride, boron nitride, etc., or composites thereof are selected.

Thermal spraying is done to uniformly coat the substrate, but pinholes on the order of 1 to 20 microns are inherently present. A solution of ladder silicone with or without a curing catalyst is applied to this surface. As a curing catalyst, para-toluenesulfonic acid,
Throat acids such as phenylphosphonic acid and citric acid are added in an amount of 0.1 to 5% based on the weight of the ladder silicone. Organic solvents such as methanol, ethanol, toluene, and xylene are used as the solvent. A coloring agent, an antifoaming agent, a filler, a thickener, and an organic polymer may be added to the ladder silicone solution.

The ladder silicone solution prepared in this way fills the pinholes well and adheres to the sprayed coating to form a strong coating.
A viscosity of ~200 cps (at room temperature) is preferred.

Any method such as brush coating, spray coating, roll coating, flow coating, etc. can be used to apply the coating to the sprayed surface. The coating thickness should be 1 to 500 microns after drying. After coating, it is dried at 50 to 200°C for about 10 to 30 seconds, and then heated at 100 to 400°C for 1 to 30 minutes to effect crosslinking and curing.

The cured film thus obtained is hard and heat resistant, and absorbs almost no moisture.

Products for which the method of the present invention is particularly effective include printed wiring boards in which a thermally sprayed insulation film is provided on a metal plate.

Example 1 A stainless steel (18Cr-8Ni) wire was thermally sprayed onto the surface of a round bar made of carbon steel with a diameter of 1 cm and a length of 1 m. The thickness of the stainless steel wire is 2mm.
The thermal spraying conditions were atmospheric thermal spraying using the arc spraying method. This thermal spraying created a 200 micron thick stainless steel coating on the carbon steel surface. Next, glass resin 650 (Owens-
A 10% toluene solution was prepared, and 1% phenylphosphonic acid was dissolved in the glass resin based on the weight of the glass resin. This solution was sprayed uniformly onto the round bar that had been thermally sprayed earlier, dried at 80°C for 10 minutes, and then heated at 200°C for 20 minutes to crosslink and cure.
The resulting round bar was coated with glass resin to a thickness of 20 microns. The surface hardness was 7H pencil hardness, and did not change at all even after heating to 600°C for 1 hour. No rust was observed even after being immersed in water for one month.

On the other hand, before glass resin coating, rust occurred in two days.

Example 2 A 1 mm thick flat plate made of SUS304 stainless steel was sprayed with zirconium oxide powder. The particle size of the zirconium oxide was 44 to 10 microns, and the spraying conditions were atmospheric spraying by plasma spraying. This thermal spraying resulted in a 300 micron thick zirconium oxide coating on the stainless steel surface. Next, glass resin 150 (Owens-
A 15% butanol/toluene solution (1:1) was prepared. This solution was coated uniformly on both sides of the previously sprayed flat plate by roller coating, and then heated in a hot air oven at 100℃ for 2 hours.
It was dried for a minute and then heated at 300°C for 5 minutes to effect crosslinking and curing.

The resulting coated plate was coated with glass resin to a thickness of 15 microns. The surface hardness was 6H pencil hardness, and did not change at all even after heating to 600°C for 1 hour. No rust was observed even after immersion in 2% hydrochloric acid for 3 months. On the other hand, before glass resin coating, rust occurred after being immersed in 2% hydrochloric acid for 2 days.

Example 3 Nickel powder was thermally sprayed onto a molded article 3 cm thick, 5 cm long and 10 cm wide, made by sintering aluminum oxide. The particle size of nickel powder is 44-10
micron, and the thermal spraying conditions were atmospheric thermal spraying using the plasma spraying method. This thermal spraying coats the surface of the sintered body.
A 250 micron thick nickel coating was created. Next, glass resin 100 is used as ladder silicone.
(manufactured by Owens-Illinois), prepare a 15% butanol solution, and prepare a 3% butanol solution based on the weight of the glass resin.
of citric acid was dissolved. This solution was applied with a brush to the previously thermally sprayed molded article, dried at 80°C for 20 minutes, and then heated at 200°C for 30 minutes to effect crosslinking and curing.
The resulting product was coated with glass resin to a thickness of 25 microns. The surface hardness was 7H pencil hardness, and there was no change at all even after heating to 600°C for 1 hour. There was no change in appearance even after being immersed in water for one month. On the other hand, the one before glass resin coating absorbed moisture and became cloudy on the surface.

Claims (1)

[Claims] 1. A method for surface treatment of a thermal spray coating, which comprises providing a thermal spray coating on the surface of a substrate, applying ladder silicone dissolved in a solvent onto the coating, and curing the coating.