JPH1143782A - Method for coating ceramic coating film and coated material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for coating which is capable of giving excellent heat resistant coating film in a short time without closing the space including the materials to be coated, and is especially suitable for coating a local part of the parts, by fist coating the substrate with gas-flame spraying method and then coating with sol-gel method. SOLUTION: The heat-resistant coating film is obtained by first coating more than once on a substrate, which is required to be highly heat-resistant, such as carbon fiber-reinforced carbon composite materials or ceramic composite materials, etc., using SiC-fiber as reinforcing fiber or substrate, with gas-flame spraying method and then coating the resulting substrate more than once with sol-gel method, or by first coating more than once on a substrate material with sol-gel method, then treating more than once the resulting substrate with gas flame-spraying method, and further treating more than once with sol-gel method to form the ceramic film on the substrate. The suitable treatment method is as follows. For example, the substrate is first treated once with gas-flame spraying method, then treated twice with sol-gel method using a low concentration liquid, and further treated five times with sol-gel method using a high concentration.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method for coating a substrate material with ceramic by a gas flame spraying method and a sol-gel method, and to a coated substrate material.

[0002]

2. Description of the Related Art The surface layer of a carbon fiber reinforced carbon composite material is made of Si.
The problem of the type coated with C and the ceramic composite material using the SiC fiber as the reinforcing fiber or the substrate is that SiC is oxidized in a high temperature environment. For example, in a carbon fiber reinforced carbon composite material, SiC is decomposed by oxidation and is scattered as a gas such as silicon monoxide and carbon monoxide to open a hole in a coating film, from which carbon fibers and a matrix as a reinforcing material are formed. Oxidation is consumed. Also, the ceramic composite material is immediately depleted of SiC fibers or matrix and further destroyed.

In order to suppress these oxidations, for example,
In Japanese Patent Publication No. 2-106337, application of various oxidation suppressing coatings on a SiC coating of a carbon fiber reinforced carbon composite material is attempted. For example, CVD on SiC coating
(Chemical Vapor Deposition
n) Application of oxide such as alumina and CVD or PVD (Phy) as an intermediate layer between SiC coating and oxide
The application of carbides, nitrides, borides, precious metals, and the like by using a physical vapor deposition is disclosed.

[0004] However, there is a problem that the application of a film by CVD requires a lot of time to obtain a target film thickness. For example, the film thickness obtained per hour is on the order of several to several tens of microns, making it difficult to respond in a short time, and high running costs.

[0005]

In view of the above situation,
An object of the present invention is to provide a substrate material that has excellent heat resistance and enables short-time construction, is particularly suitable for local construction of parts, and does not require equipment for sealing a space containing a construction object upon construction. And a material coated by this method.

[0006]

Means for Solving the Problems In order to achieve the above-mentioned object, the present inventors have made intensive studies and as a result, the present invention is based on the finding that the substrate material is first formed by a gas flame spraying method and then by a sol-gel method. Characterized in that it is coated, and the substrate material is first ceramic coated by a sol-gel method, then a gas flame spraying method, and then by a sol-gel method, and further the material coated by these coating methods It is characterized by.

[0007] The substrate material of the present invention may be any material as long as heat resistance is required. Examples thereof include ceramics, carbon materials coated with ceramics and ceramic composite materials. Carbon fiber reinforced carbon composite material with conversion SiC coated with SiC (silicon carbide) by the CVD method (hereinafter abbreviated as C / C with conversion SiC), and CV whose surface layer is coated with SiC (silicon carbide) by the CVD method
Carbon fiber reinforced carbon composite material with DSiC (hereinafter referred to as CVDSi
C / C) and ceramic composites using SiC as a reinforcing fiber or substrate.

The carbon fiber reinforced carbon composite material is made of, for example, graphite obtained from polyacrylonitrile (PAN), pitch or rayon or carbon fiber as a reinforcing material, and a resin such as graphite obtained by graphitizing or carbonizing a phenol resin. Conversion with carbon as matrix, C
Includes composite materials obtained by coating SiC with VD or the like.

[0009] Ceramic composite materials using SiC as a reinforcing material include those using SiC fibers or SiC whiskers or particles as a reinforcing material and using alumina as a matrix.

[0010] The surface of the substrate material is desirably removed of, for example, an oil agent, dust and the like before the formation of the film.

The apparatus used in the gas flame spraying method of the present invention uses acetylene-oxygen as a combustion gas and performs spraying by the jet effect of compressed air.
It consists of a gas cylinder, a flow meter, a raw material container, and an air supply device, and can apply a ceramic coating in a short time. For example, it is possible to coat a 30 mm square C / C material with an alumina coating having a thickness of about 20 microns in a few seconds. it can.

The distance between the coating material and the nozzle face of the spray gun is preferably 40 to 150 mm, particularly preferably 40 to 150 mm.
８０80 mm.

The particle size of the ceramic forming the coating of the present invention is preferably 5 to 150 microns, particularly preferably 5 to 150 microns.
50 microns. The flow rate of the ceramic supplied from the raw material container is preferably from 10 to 40 g / min, particularly preferably from 10 to 20 g / min. The spray time of the ceramic in the gas flame spraying method is preferably 2 to 10 seconds, and particularly preferably 4 to 5 seconds. The thickness of the ceramic formed on the surface of the substrate material is preferably from 10 to 50 microns, particularly preferably from 20 to 30 microns.

The sol-gel method used for forming the coating of the present invention is as follows.
The material for forming a film is brought into contact with a metal precursor solution obtained by hydrolyzing a metal alkoxide, and the precursor solution penetrates and / or adheres to the surface of the material, especially voids, recesses, and the like, and after drying, heat treatment is performed. An oxide film is formed, and this film has excellent adhesion to a substrate material and excellent peel resistance against impact and the like.
Examples of the method of injecting and / or attaching the precursor solution to the material surface include immersing the material in the precursor solution, spraying the precursor solution on the material surface, and applying the precursor solution to the material surface. Any method is applicable as long as the solution can penetrate and / or adhere. In order to allow the precursor solution to sufficiently penetrate into voids and the like, immersion treatment under reduced pressure is particularly preferable. The preferred precursor concentration is 0.2 to 1.1 mol / l. The preferred method of treatment by the sol-gel method is that the low concentration
A film is formed on the surface of the material with a precursor solution of preferably 0.00001 to 0.4 mol / l, and then at least once at a high concentration, preferably 0.6 to 1.1 mol / l.
Is to form a film with the precursor solution of the above.

In the preferred coating formation of the present invention, the gas flame spraying method is first applied to the surface of the substrate material at least once, and then the sol-gel method is applied at least once (case 1), or the sol-gel method is applied first. Is applied at least once, and thereafter, the gas flame spraying method is applied at least once, and the sol-gel method is applied at least once (case 2). The preferred number of applications for each is, in case 1, one gas flame spray, then two sol-gel processes at low concentrations and five sol-gel processes at high concentrations.
Do it twice. In case 2, the sol-gel method was first used at a low concentration.
Times, followed by gas flame spraying once, followed by low-concentration sol-gel method twice, and then high-concentration sol-gel five times.

[0016]

【Example】

Experimental Example 1 Formation of Alumina Coating by Gas Flame Spray Method C / C with Conversion SiC (Size: 30 mm × 3
(0 mm × 3 mmt), an alumina coating was formed by a gas flame spraying method.

The apparatus used for the gas flame spraying method is a high-speed gas spraying apparatus TERODYN S manufactured by Utech Japan Co., Ltd.
Purity 9 with YSTEM 3000 having a particle size of substantially 7-50 microns (7-50 microns content 93% by weight)
9.91% alumina was sprayed while maintaining the distance between the substrate and the nozzle surface of the spraying apparatus at about 80 mm to obtain a film having a thickness of about 20 microns. The substrate having the obtained thermal spray coating was subjected to coating formation using a sol-gel precursor solution.

Preparation of Alumina Precursor Deionized water was placed in a flask equipped with a heater and a stirrer and heated to 90 ° C. with stirring. Under these conditions 99.
9% aluminum triisopropoxide was slowly added into the flask. Thirty minutes after the completion of the addition, 99.5% acetic acid was added, and the mixture was stirred at 90 ° C. for 48 hours, then transferred to a sealed container and stored in a cool and dark place. At this time, the mixing ratio of deionized water, aluminum triisopropoxide and acetic acid was 100: 2:
0.2 (molar ratio).

Formation of Alumina Coating by Sol-Gel Method A substrate having a sprayed alumina coating is impregnated with an alumina precursor solution and dried in a drying oven at 100 ° C.
The temperature was increased to 1200 ° C. at a rate of 600 ° C./hour in an inert gas or vacuum heat treatment furnace, heat-treated at this temperature for 1 hour, and allowed to cool. This film formation was repeated five times to form a 5 μm thick sol-gel coating on the approximately 20 μm thick sprayed coating.

Evaluation of Heat Resistance (Oxidation Resistance) The heat resistance was evaluated by a repeated static heating load test at 1500 ° C. (expected hull surface temperature when the spacecraft hull enters the atmosphere). Exposure was performed in an environment of 1500 ° C. for 16 minutes (time during which the hull was exposed to a high temperature in one entry into the atmosphere), and this treatment was repeated three times. Scanning electron microscope, X-ray microanalyzer and X-ray
The heat resistance was evaluated based on the degree of oxidative damage of the film formed on the substrate by analyzing using a line diffractometer.

The substrate having the coating of the present invention obtained in Experimental Example 1 showed almost no damage to the coating even after the above heat exposure, and was extremely excellent in heat resistance.

EXPERIMENTAL EXAMPLE 2 In the same manner as in Experimental Example 1, a commercially available ceramic composite material using SiC as a reinforcing material has a particle size of substantially 5 to 30 microns (containing 5 to 30 microns) using the same apparatus as in Experimental Example 1. Volume 90
(% By weight) of alumina having a purity of 99.91% was sprayed under the same conditions as in Experimental Example 1 to obtain a sprayed alumina coating of 20 microns. The substrate having the obtained thermal spray coating was subjected to coating formation by a sol-gel method.

Mixing ratio of water, aluminum triisopropoxide and acetic acid 100: 0.75: 0.2 (molar ratio)
A low-concentration alumina precursor solution was prepared in the same manner as in Experimental Example 1 except that

Using the above alumina precursor solution,
An alumina coating was formed on the substrate in the same manner as in Experimental Example 1. The number of repetitions of the coating application was two.

Using the alumina precursor solution of Experimental Example 1, an alumina film was formed on the substrate in the same manner as in Experimental Example 1. However, the film was formed five times. The thickness of the entire alumina coating finally obtained was 25 microns. The obtained material of the present invention was evaluated for heat resistance in the same manner as in Experimental Example 1, and found to have extremely excellent heat resistance.

Experimental Example 3 A low-concentration alumina precursor was prepared in the same manner as in Experimental Example 1 except that the mixing ratio of water, aluminum triisopropoxide and acetic acid was 100: 0.75: 0.2 (molar ratio). A solution was prepared.

Using this alumina precursor solution, an alumina coating was formed on a commercially available ceramic composite material using SiC as a reinforcing material. The number of repetitions of film formation was two. The particle size is substantially 5 on this coating.
Alumina having a purity of 30 microns (5 to 30 microns content 90% by weight) and a purity of 99.91% was sprayed in the same manner as in Experimental Example 1 to obtain a sprayed film having a thickness of 20 microns on the sol-gel film. A sol-gel coating was formed on this thermal spray coating using the alumina precursor solution used in Experimental Example 1. This film was formed five times. The obtained material of the present invention was evaluated for heat resistance in the same manner as in Experimental Example 1, and found to have extremely excellent heat resistance.

COMPARATIVE EXPERIMENTAL EXAMPLE 1 Except that the formation of the sol-gel coating was omitted, Experimental Example 1 was omitted.
A substrate having only a thermal spray coating was obtained in the same manner as in the above. When the obtained coating film was analyzed with the analytical instrument described in Experimental Example 1, voids reaching the substrate were found in some places. In the evaluation of heat resistance, SiC as a substrate was decomposed and damaged by oxidation, and carbon fibers and matrix carbon as reinforcing materials were oxidized and consumed therefrom.

Comparative Experimental Example 2 A substrate having only a sol-gel coating was obtained in the same manner as in Experimental Example 1, except that the formation of the thermal spray coating was omitted. When the coating obtained by the analytical instrument described in Experimental Example 1 was analyzed, slight cracks and voids were found. In the evaluation of heat resistance, the substrate was slightly oxidized and consumed as in Comparative Example 1.

Comparative Experimental Example 3 A substrate having a thermal spray coating on a sol-gel coating was obtained in the same manner as in Experimental Example 3, except that the formation of the sol-gel coating on the thermal spray coating was omitted. When the coating obtained by the analytical instrument described in Experimental Example 1 was analyzed, a defective portion of the alumina coating leading to the substrate and a separated portion between the substrate and the alumina coating were found.

[0031]

The film obtained by the method of the present invention and the material having this film have excellent heat resistance and excellent adhesion between the coating and the substrate material, and can form a film on substrates of any shape. You can do it. In particular, it is useful for repairing external heat-resistant coatings on spacecraft hulls.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI D06M 11/36 D06M 11/12 11/77

Claims (7)

[Claims] 1. The method according to claim 1, wherein the substrate material is first gas flame sprayed,
Thereafter, a ceramic coating is performed by a sol-gel method. 2. The coating method according to claim 1, wherein the substrate material is first ceramic coated by a sol-gel method, then by a gas flame spraying method and then by a sol-gel method. 3. The coating method according to claim 1, wherein the substrate material is a carbon fiber reinforced carbon composite material or a ceramic composite material using SiC fibers as a reinforcement fiber or a substrate. 4. The coating method according to claim 1, wherein the formation of the ceramic coating by the sol-gel method is performed using a low concentration ceramic precursor and thereafter using a high concentration ceramic precursor. 5. The method according to claim 1, wherein the formation of the ceramic coating by the sol-gel method is performed at least once continuously and / or the formation of the ceramic coating by the gas flame spraying method is performed at least once continuously. 5. The coating method according to any one of claims 1 to 4. 6. The coating method according to claim 1, wherein the formation of the ceramic coating is performed in an open space. 7. A material coated by the coating method according to claim 1.