JPS5912749B2 - Ceramitsukyoushiyahimaku - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a thermal spray coating treatment method that has succeeded in greatly improving the discoloration resistance and adhesion of ceramic coatings sprayed onto metal materials in corrosive environments.

At2o3, 2ro2 on the surface of conventional metal materials.

Ti02, cao29sio2, Feo2, Cr2O3
When coating a ceramic sprayed film such as and leaving it in a corrosive environment, the surface of the coating layer will inevitably become contaminated with compounds of ions eluted from the underlying metal, causing discoloration.If this contamination progresses further, the underlying metal will deteriorate. Problems such as pitting corrosion and peeling of the surface layer occurred. This is because the ceramic thermally sprayed coating is relatively porous, and corrosive liquid that enters through it will attack the base surface. In addition, in the pre-treatment process for thermal spray coating,
The surface of the substrate is processed by sandplast, etc., and the corrosion resistance of the substrate surface is reduced due to the stress of this processing, and the corrosion resistance is reduced due to alteration of the outermost surface of the substrate due to thermal spraying heat, which further accelerates corrosion. For this reason, when using products with ceramic sprayed coatings in highly corrosive environments today, it is recommended to use materials with higher corrosion resistance as the base material, such as high-grade austenitic stainless steel, Ti alloys, etc., or to use organic materials in the pores of the coating. Countermeasures have been taken, such as impregnating the substrate with a material to prevent the intrusion of corrosive liquids, or pre-treatment by thermally spraying a highly corrosion-resistant alloy onto the surface of the substrate. Among these measures, improving the quality of materials is quite effective, but if there are constraints from cost and processing aspects, it is difficult to freely select materials, and as shown above, It is inevitable that the corrosion resistance of the surface will be lower than the original corrosion resistance of the base material.

In addition, the effect of impregnating the pores of the coating with an organic substance is recognized, but the organic substance generally shrinks by 25% during the solidification process. Therefore, unless the wettability between the inner surface of the bore and the impregnated organic matter is high,
A gap is created in between, and corrosive liquid can enter this area, so it cannot be said that this is a partial corrosion protection treatment. Furthermore, in the case of organic materials, it is inevitable that they will change color due to ultraviolet rays, and therefore cannot be used in products where the color tone of the appearance is considered important. Base thermal spray coating of highly corrosion-resistant materials is quite effective, but it is costly, and if the base thermal spray coating does not completely cover the base material, local batteries may occur due to the difference in ionization tendency from the base material. However, there is a possibility that the corrosion mountain will progress further. In view of these facts, the present invention has improved the thermal spraying pre-treatment method to form a dense ceramic coating layer between the substrate and the ceramic coating, and at the same time improved the pore sealing process to form a dense ceramic coating layer into the pores of the thermal spray coating. Enclosed with ceramics,
After that, heat treatment is performed to cause heat to diffuse between these oxides and the sprayed oxide, thereby completely preventing corrosion of the base material in a corrosive environment.

Generally, as a pretreatment for thermal spray coating, a process of roughening the surface by sandblasting, chemical corrosion, Mo coating, etc. is used to improve the adhesion of the coating.

In the present invention, after these surface roughening steps, At,
Alkyl compounds of metals such as Zr, Ti, Si, Cr, Ta, metal-r complexes, allyl compound acylate compounds,
A dense metal oxide film produced by a cracking reaction of an alkoxy compound is coated, and then thermal spraying is performed over this according to a conventional method. Furthermore, the above-mentioned compound is impregnated into the pores from the surface of the sprayed coating and cracked to seal the pores with a metal oxide, and then the intermediate oxide coating and the space between the oxide in the pores and the sprayed oxide are sealed. The heat treatment is carried out under a temperature condition of above the solid diffusion starting temperature and below the base material melting starting temperature. By performing such treatment before and after thermal spraying, and then applying heat treatment, the adhesion between the oxide film on the substrate and the thermal sprayed film is improved, and most of 0penpore is CTO-based EDP.
ore, and the minute CtoBedpore disappears.

In this way, corrosive liquids are prevented from entering from the sprayed coating bore, and even if they do, they are shut out by the metal oxide coating layer on the surface of the base metal, completely preventing corrosion of the base metal. It can be prevented. Specifically, in the thermal spraying pretreatment, the above compound is dissolved in an appropriate solvent at an appropriate concentration, coated by spraying, dipping, coating, etc., and left in the air or subjected to heat treatment to cause a cracking reaction.

After spraying, the sealing material is coated with spraying, dipping, coating, etc., and the pores are penetrated internally using the two-layer phenomenon, or they are forcibly penetrated using vacuum operation, etc. cause a cracking reaction. Although the pretreatment coating is extremely effective even with a negative layer, the effect becomes even greater if two or more layers of the same oxide or different oxides are coated.
Similarly, it is effective to perform sealing treatment once or twice or more. Further, the subsequent heat treatment is carried out in the air or in an atmospheric gas, followed by gradual cooling. The present invention will be explained below with reference to Examples.

Example 1 On the surface of fully austenitized SUS304 material,
After the usual pretreatment, the surface was coated with a 10(:f) isopropyl solution of hetetraisopropyl titanate, dried at a relative humidity of 20% or less at a temperature of 30°C, and then exposed to air for 1200°C. ℃, 2 hr heat treatment,
A 100μ At, o, +TiO2 coating was thermally sprayed onto this, and this thermally sprayed layer was impregnated with a 40% isopropyl solution of hetetrabutyl titanate using a vacuum device, and dried at a temperature of 50°C.

This material was stored at a temperature of 300°C in a vacuum of 10-3 dew hours.
After holding for 3 hours, it was held at 1200° C. for 3 hours in oxygen gas, and then cooled in the furnace for 24 hours. At the same time, a total of 50 samples of 4 types were prepared, including a fully austenitized SUS304 material whose surface was polished with a cloth, a material that had been thermally sprayed using a conventional method, and a material whose thermally sprayed layer was impregnated with organic matter. We created and conducted corrosion tests. In the corrosion test, the sample was immersed in a 5-wound NaCρ solution at a temperature of 50° C., and the state of discoloration of the surface layer was investigated. In addition, the test results were compared based on the average time of discoloration of 50 samples, and the following results were obtained. Red rust appeared on the ordinary shot product on the 5th day, on the 9th day on the fabric abrasive product, on the 11th day on the regular sealed product, and on the 30th day on the product of the present invention, which clearly shows that the product of the present invention was found to be highly effective. Example 2 SVS3 manufactured through a process of water cooling (water temperature 24°C) after holding in ammonia decomposition gas at 1150°C for 30min
800 mirror-polished watch cases made of 04 material were prepared.

This sample was divided into 100 pieces and designated as sample black A, B, C, . . . , H, respectively. Samples B and C
,D,...,Sandblasting 320 on the surface of H
# was applied at 3 atm for 5 minutes.

For sample D, At(oiS0c3H7)31
0r is triethane 100CC1 acetylacetone 2CC
immersed in a solution (tentatively named Solution D) dissolved in a mixed solvent of
After dipping, it was dried and fired at 600° C. for 1 hour in the air. For sample E, Zr(OC8H1,)420r was immersed in a solution (tentatively named as E solution) in which 50 cc of methyl acetate and 50 cc of isopropyl alcohol were dissolved, and after immersion, it was dried and baked at 120°C in the air for 30 min. .

For sample F, 410t of Si(0CH3) was mixed with 50CC1 of methyl acetate, 50CC1 of isopropyl alcohol
1q1) A solution (F
After immersion, the temperature was 80°C and 30°C in the atmosphere.
After drying for a minute, it was fired at 450°C for 30 minutes.

For sample G, the sample was heated to 500°C in the atmosphere, and 5t of chromium acetylacetonate was mixed with 10t of triethane.
A solution dissolved in 0CC (tentatively named Solution G) was sprayed.

For sample H, 55t of Ta(0c2H5) was mixed with 50cc of ethyl acetate, 50cc of isopropyl alcohol,
A solution containing 1 CC of lactic acid dissolved in a mixed solvent (tentatively named as H solution)
After dipping, the sample was dried in the air at 80°C for 30 minutes, and then baked at 500°C for 1 hour.

A TiO2 coating of 120 μm was thermally sprayed onto the surfaces of these 6 types of samples C, D, .

Furthermore, regarding the five types of samples D, E, F, G, and H,
The D, E, F, G, and H solutions were immersed, fired, and diffused in the same steps as the thermal spraying pretreatment.

As described above, 8 kinds of samples A, B, C, .

When we investigated the occurrence of discoloration and red rust after 20 days, we found that
The results are shown in Table 1, confirming that the product of the present invention has extremely good corrosion resistance.

Claims (1)

[Claims] 1 An alkyl compound, a metal-r-complex, an allyl compound of a metal such as Al, Zr, Ti, Si, Cr, or Ta between the sprayed material and the ceramic sprayed coating and in the pores of the sprayed coating;
Contains one or more metal oxides produced by cracking reactions of arecito compounds, chelate compounds, composite compounds, and alkoxy compounds, and has a thermal diffusion layer at the boundary between this oxide and the sprayed coating. Ceramic sprayed coating featuring: