JP7393961B2 - Heat resistant member and its manufacturing method - Google Patents

Description

The present invention relates to a highly durable heat-resistant member that can be used for a long time even if the inside is in a high-temperature oxidizing atmosphere.

In general, carbon materials such as graphite, graphene, and carbon nanotubes, and metal materials such as stainless steel, have moldability and high heat resistance, so they are used in industrial applications such as gasket packing, electrodes, heaters, and circuit wiring. It is widely used in the industry, and in recent years there has been a demand for even greater durability at high temperatures.

However, at high temperatures and in an oxidizing atmosphere, the surface of the carbon member is oxidized, causing it to disappear and deteriorate. In addition, when stainless steel parts are exposed to high temperatures of 800°C or higher, the surface of the part is oxidized and the metal ions in the alloy diffuse outward to the oxide and oxygen interface, causing the entire part to become an oxide, causing surface peeling and mechanical damage. Strength and conductivity will decrease.

For this reason, research and development is being conducted with the aim of improving environmental resistance. Specifically, an oxide film is formed on the surface of the component to block oxygen from the outside (oxygen inward diffusion) and suppress metal ion diffusion from the component side (metal ion outward diffusion). Efforts are being made to dope metal elements to suppress metal diffusion within the alloy.

For example, attempts have been reported to improve oxidation and corrosion resistance by hydrolyzing metal alkoxides and producing a metal oxide sol solution through a polycondensation reaction and coating it on a stainless steel substrate to form a protective film. There is.
However, the membrane produced by the above method has fine pores, and the effect of suppressing surface oxidation may not be sufficient. In addition, alumina, silica, or alumina-silica composite films can relatively suppress oxidation on the surface of parts up to about 800°C, but at higher temperatures, chromium, iron, etc. It is difficult to sufficiently suppress metal ions from diffusing from the alloy into the oxide film, and furthermore, from reaching the surface and precipitating as oxides. Therefore, there was a problem that mechanical strength and electrical conductivity decreased. (Non-patent document 1)

Furthermore, a method has been reported in which a specific stainless steel is heat treated to deposit metal oxides on the surface to form a coating. However, with this method, the film composition and film thickness change depending on the heat treatment temperature, and at high temperatures of 900°C or higher, the adhesion with the component decreases due to the difference in thermal expansion and peeling occurs. This poses a problem in terms of cost because it requires storage. (Patent Document 1)

Furthermore, anti-corrosion coated steel materials have been reported in which aerosolized solid fine particles having high corrosion resistance are sprayed onto the surface of the steel materials. Furthermore, a gas deposition method has been reported in which a carrier gas and fine particles are simultaneously conveyed onto a substrate to form a fine particle film. However, with the above method, it is difficult to uniformly form a film in a complex shape or in fine pores. (Patent Document 2 and Patent Document 3)

Furthermore, there have been reports of a coating having excellent heat resistance and high adhesion by forming a composite oxide coating containing lanthanide elements and 3B group elements such as Al, B, and Ga on a carbon base material. However, since the content of lanthanide oxide is high, there are problems in terms of cost, and furthermore, since an intermediate layer of tungsten is required, there are problems in terms of the film forming process. (Patent Document 4)

JP 11-156194 JP2007-146266 JP 6-116743 JP2009-1485

Journal of the Japan Institute of Metals, Vol. 55, No. 12 (1991) 1345-1352

To provide a heat-resistant member that is inexpensive, industrially usable, and usable in an oxidizing atmosphere of 800°C to 1,500°C.

The present inventors have conducted extensive studies with the aim of developing an inexpensive manufacturing method for providing the heat-resistant member described in the preceding section, and as a result, we have developed an oxide film consisting of oxides of Al, Si, Ce, and Zr using a sol-gel method. We have discovered that extremely high heat resistance can be imparted to complex shapes and fine structures by coating the surface of the component with a heat treatment method.

Specifically, by coating the surface of the carbon member with the oxide of claims 1 and 3, it is possible to reduce the loss of the carbon member due to internal diffusion of oxygen ions to the oxide/carbon interface, and further, By coating the surface of the metal member with the oxide of Claims 1 and 3, metal ions in the oxide film diffuse outward from the member side to the oxide/oxygen interface, and oxygen ions from the oxygen side to the member/oxide interface. It has been found that by suppressing internal cross-diffusion, durability in high-temperature atmospheres can be significantly improved, resulting in improved heat resistance.

The gist of the invention is as follows.

(1) A heat-resistant member having a coating on its surface that satisfies all of the following (a) to (c) (a) Made of oxides of aluminum, zirconium, cerium, and silicon (b) Each of zirconium, cerium, and silicon for aluminum The atomic ratio satisfies all of the following (a) to (d) (atomic ratio)
Zr/Al=0.001 or more -(A)
Ce/Al=0.001 or more -(A)
Si/Al=0.001 or more -(C)
And (Si+Ce+Zr)/Al=0.01~0.5 -(D)
(c) Average film thickness of the coating is 0.01 to 30.0 μm

(2) The heat-resistant member according to (1), wherein the coating coats the surface of one or more of carbon or stainless steel with a melting point of 1,500° C. or higher.

(3) The aluminum oxide of the coating has at least one crystal form among amorphous, pseudoboehmite, boehmite, γ-alumina, θ-alumina, δ-alumina, and α-alumina (1) The heat-resistant member described.

(4) A liquid mixture consisting of an aluminum compound, a zirconia compound, a cerium compound, and a silicon compound that satisfies (1) and (3) above is applied to the surface of the member described in (2), and after drying, the mixture is heated to 100 to 1,500°C. The method for producing a heat-resistant member according to (1) to (3), comprising the heat treatment step of

It is possible to provide a heat-resistant member that can be used in an oxidizing atmosphere of 800°C to 1,500°C.

Furthermore, since the heat resistance of the member has been improved, the durability time when used at high temperatures has also been significantly improved, making it possible to contribute to the development of a wider range of industries. Further, since the coated oxide film is electrically conductive, the heat-resistant member of the present invention can also be used for electrodes and the like. Therefore, we believe that we were able to provide high heat resistance and durability as a conductive member.

FIG. 1 is a SEM photograph of the surface of the coating obtained in Example 1. FIG. 2 is a SEM photograph of the surface of the coating obtained in Comparative Example 1.

Embodiments of the present invention will be described below.

Composition of Oxide Film The oxide film constituting the present invention satisfies all of the following (a) to (b).
(a) Consists of oxides of aluminum, zirconium, cerium, and silicon (b) The atomic ratio of zirconium, cerium, and silicon to aluminum satisfies all of the following (a) to (d) (atomic ratio)
Zr/Al=0.001 or more -(A)
Ce/Al=0.001 or more -(A)
Si/Al=0.001 or more -(C)
And (Si+Ce+Zr)/Al=0.01~0.5 -(D)

If the atomic ratio of each of zirconium, cerium, and silicon to aluminum in the oxide film is less than 0.001 and/or the total atomic ratio of zirconium, cerium, and silicon to aluminum in the oxide film is less than 0.01, a high temperature atmosphere Under these conditions, the internal diffusion rate of oxygen in the oxide film and the external diffusion rate of metal ions in the member increase, and deterioration (oxidation) of the member may progress significantly.

If the total atomic ratio of zirconium, cerium, and silicon to aluminum in the oxide film exceeds 0.5, the member may deteriorate and the adhesion of the oxide film to the substrate may decrease.

Thickness of oxide film The thickness of the oxide film of the present invention can be easily adjusted by adjusting the concentration of alumina in the dispersion medium. When the alumina concentration is low, a thin film is formed, and when it is high, a thick film is formed, and by adjusting the concentration, a desired film thickness can be obtained. Further, the coating operation can be repeated as necessary to obtain a coating having a desired thickness.

The thickness of the coating film constituting the present invention is preferably 0.01 μm or more and 30.0 μm or less since a film with sufficient heat resistance can be formed. If it is less than 0.01 μm, a sufficient effect of improving heat resistance cannot be obtained, and if it exceeds 30 μm, the adhesiveness with the member may decrease and peeling may occur. Regarding the film thickness, apply a 50 μm thick masking tape (Nichiban Cellotape (registered trademark) CT1535-5P or equivalent) near the center of the SUS substrate, coat it with the coating solution, dry it, heat it at 150°C, and then peel off the masking tape. The cross section was observed with a scanning electron microscope (FE-SEM: S-4800 manufactured by Hitachi High Technologies). Three samples were prepared under the same conditions, cross sections were measured under the same conditions, and the average value was taken as the film thickness.

Crystal structure The crystal structure of the aluminum oxide in the oxide film constituting the heat-resistant conductive member of the present invention is selected from boehmite, γ-alumina, θ-alumina, δ-alumina, and α-alumina by appropriately selecting it. It is at least one type, preferably boehmite, γ-alumina, θ-alumina, or δ-alumina, and the crystal system ultimately changes to α-alumina by heat treatment. The crystal structure can be confirmed, for example, by measuring with an X-ray diffraction device (SmartLab manufactured by Rigaku).

Particle shape The shape and size of alumina particles in the coating solution are not particularly limited, but plate-like, columnar, fibrous, spherical, etc. can be used. Regarding the size, if the shortest diameter of the primary crystal particles exceeds 500 nm, Adhesion to the substrate may deteriorate, and furthermore, it may become difficult to coat fine pores or shapes. It can be confirmed that the particles have the above shape and size, for example, by observing them using a scanning electron microscope (FE-SEM: Hitachi High-Technologies S-4800) at a magnification of about 30,000 times. can.

Aluminum Source Aluminum sources include hydrolyzable inorganic and organic aluminum, and examples of inorganic aluminum include aluminum chloride, aluminum nitrate, and aluminum sulfate. Aluminum alkoxides such as aluminum ethoxide, aluminum isopropoxide, aluminum n-butoxide, aluminum sec-butoxide, cyclic aluminum oligomers, aluminum chelates such as diisopropoxy(ethylacetoacetato)aluminum, tris(ethylacetoacetate)aluminum Examples include organoaluminum compounds such as aluminum alkyl, ammonium aluminum carbonate, and carboxylic acid salts such as aluminum acetate.
Furthermore, inorganic or organic aluminum hydrolysates and oxides may be used. Specific examples include aluminum hydroxide, bayerite, gibbsite, pseudoboehmite, boehmite, γ-alumina, θ-alumina, δ-alumina, and α-alumina. Preferably, aluminum hydroxide, gibbsite, pseudo-boehmite, and boehmite are preferred from the viewpoint of adhesion to the member.

Zirconia compounds Zirconia compounds include salts such as zirconium (III) chloride, zirconium (IV) chloride, zirconium nitrate, zirconium acetate, and zirconium ammonium carbonate, as well as zirconium isopropoxide, zirconium butoxide, and zirconium tetra(acetylacetonate). For example,

Cerium Compound Examples of cerium compounds include cerium nitrate, cerium carbonate, salem chloride, and cerium hydroxide.

Silicon compounds Examples of silicon compounds include tetramethoxysilane, tetraethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropyltrimethoxysilane, - Glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane Examples include roxypropylmethyldiethoxysilane, 3-methacryloxypropyltriethoxysilane, and the like.

Base material The base material of the heat-resistant member constituting the present invention may include carbon members made of carbon fiber and/or its sintered body, graphite, graphene, carbon nanotubes, martensitic stainless steel, ferritic stainless steel, etc. , austenitic stainless steel, austenitic ferritic stainless steel, and other stainless steels.

Heat resistance Although sufficient effects are exhibited even at temperatures below 800°C, the superiority of the member of the present invention is low because the metal ion diffusion rate in the oxide film is not high. Furthermore, at temperatures above 1,500° C., the coating may peel off depending on the member, making it difficult to maintain sufficient heat resistance. Heat resistance when the base material was stainless steel was judged based on the adhesion of the oxide film and the presence or absence of crystals derived from Cr ₂ O ₃ . Raise the temperature from room temperature to 1,000°C or 1,500°C at a rate of 10°C/min, hold at 1,000°C or 1,500°C for 24 hours, let it cool naturally, and then visually observe that the oxide film has peeled off. Cr ₂ O ₃ observed when Cr ions diffuse outward under 30,000x magnification using a scanning electron microscope (FE-SEM: Hitachi High-Technologies S-4800). A coating in which no native crystals were observed was judged to be heat resistant.
The heat resistance when the base material was a carbon member was judged based on the weight reduction rate. Using TG-DTA (2000SA, manufactured by Bruker AX), the temperature was raised from room temperature to 800°C at a rate of 10°C/min. The weight loss rate at this time was measured, and if the weight loss rate was 30% or less, it was determined that the product had heat resistance.

Manufacturing method The heat-resistant member constituting the present invention can be manufactured by applying a coating liquid consisting of an aluminum compound, a zirconia compound, a cerium compound, and a silicon compound to the surface of the member, and after drying, heat-treating at 100 to 1,500°C. I can do it.

If the treatment temperature is less than 100°C, the adhesion with the component may decrease, and if it exceeds 1,500℃, the adhesion will decrease and cracks may occur, and metal ions from the component may decrease. It may become difficult to suppress the outward diffusion of acid ions and the inward diffusion of acid ions from the oxygen side. The temperature is more preferably 100° C. to 800° C. from the viewpoint of cost such as reduction of energy consumption and required time.

Coating Liquid Since the composition of the coating liquid can be controlled at the molecular level, a coating liquid prepared by a sol-gel method can be suitably used. Compared to PVD, CVD, thermal spraying, etc., it can be applied uniformly to large-area and complex-shaped substrates, the composition can be controlled at the molecular level, and the initial capital investment is low, making it possible to form films at low cost. There are advantages such as being able to

Coating Method As the coating method, various general methods for coating various members can be adopted depending on the desired shape and thickness of the film. For example, methods include methods in which the coating liquid is uniformly applied to the component by spraying, methods in which the coating liquid is applied to the surface by roll coating, etc., methods in which the component is immersed in the coating solution for a certain period of time, then withdrawn at a constant speed, excess liquid is removed, and then dried. Law can be exemplified.

Next, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to the following Examples.

Example 1 (Zr+Ce+Si)/Al=0.05
Into a 500 ml four-necked flask, 300 g of ion-exchanged water, 0.86 g of 62% nitric acid aqueous solution, and 34 g (0.17 mol) of aluminum isoporopoxide were charged, and the mixture was raised while stirring, and the isopropyl alcohol generated was distilled out. , the liquid temperature was raised to 95°C. Furthermore, the reaction solution was transferred to a stirring autoclave, and the reaction was carried out at 150° C. for 1 hour. The reaction solution was cooled to 40°C or lower to synthesize an alumina sol. To this alumina sol were added 0.53 g (0.002 mol) of zirconium oxynitrate dihydrate, 1.1 g (0.0025 mol) of cerium nitrate hexahydrate and acetic acid, and 0.8 g (0.002 mol) of tetraethoxysilane. The mixture was stirred for 30 minutes to obtain a coating solution. The solid content concentration in the reaction solution was 3.0% by mass.
Next, a 50 mm x 50 mm stainless steel (SUS304) substrate that had been degreased with acetone was immersed in the coating solution for 5 minutes. Thereafter, the substrate was slowly pulled up and dried at 30° C. for 2 hours, and then sintered at 120° C. for 2 hours to produce a heat-resistant member in which stainless steel was coated with a colorless and transparent film having a thickness of 0.8 μm.
Regarding the film thickness, a masking tape with a thickness of 50 μm was pasted near the center of the SUS substrate, and after coating with the coating solution, it was dried and heat-treated at 150°C, the masking tape was peeled off, and the cross section was examined using a scanning electron microscope (FE-SEM: Hitachi The film thickness was determined by observing with a Hi-Technologies S-4800). Three samples were prepared under the same conditions, cross sections were measured under the same conditions, and the average value was taken as the film thickness. Regarding the film thickness measurement, the same operation was performed below.
As a result of measuring the heat-resistant member with an X-ray diffraction device (SmartLab manufactured by Rigaku), it was found to have a boehmite structure. This heat-resistant member was heated from room temperature to 1,000°C at a rate of 10°C/min, held at 1,000°C for 24 hours, and then allowed to cool naturally. Visual observation revealed that the oxide film did not peel off. It was stuck tightly to the stainless steel. In addition, the surface of the member treated at 1,000°C was magnified 30,000 times using a scanning electron microscope (FE-SEM: Hitachi High-Technologies S-4800), and the external diffusion of Cr ions was observed. As a result of observing the crystals derived from Cr ₂ O ₃ (FIG. 1), no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Example 2 (Zr+Ce+Si)/Al=0.05
In a 500 ml four-necked flask, add 300 g of ion exchange water, 0.86 g of 62% nitric acid aqueous solution, 34 g (0.17 mol) of aluminum isoporopoxide, 0.53 g (0.002 mol) of zirconium oxynitrate dihydrate, and cerium nitrate. 1.1 g (0.0025 mol) of hexahydrate acetic acid and 0.8 g (0.002 mol) of tetraethoxysilane were charged, and the temperature was raised to 95° C. while stirring to distill off the generated isopropyl alcohol. raised to. The reaction solution was cooled to 40° C. or lower to complete the reaction and obtain a coating solution. The solid content concentration in the reaction solution was 3.0% by mass.
Next, a 50 mm x 50 mm stainless steel (SUS304) substrate that had been degreased with acetone was immersed in the coating solution for 5 minutes. Thereafter, the substrate was slowly pulled up and dried at 30° C. for 2 hours, and then sintered at 150° C. for 2 hours to produce a heat-resistant member in which stainless steel was coated with a colorless and transparent film having a thickness of 0.8 μm.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was found that the oxide film did not peel off and was in close contact with the stainless steel. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Example 3 (Zr+Ce+Si)/Al=0.3
Example 1 except that 2.7 g (0.01 mol) of zirconium oxynitrate dihydrate, 4.3 g (0.01 mol) of cerium nitrate hexahydrate, and 6.5 g (0.03 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was found that the oxide film did not peel off and was in close contact with the stainless steel. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Example 4 (Zr+Ce+Si)/Al=0.45
Example 1 except that 6.6 g (0.025 mol) of zirconium oxynitrate dihydrate, 6.4 g (0.015 mol) of cerium nitrate hexahydrate, and 7.7 g (0.037 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was found that the oxide film did not peel off and was in close contact with the stainless steel. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Example 5 (Zr+Ce+Si)/Al=0.3 Zr=0.007
Example 1 except that 0.32 g (0.001 mol) of zirconium oxynitrate dihydrate, 7.3 g (0.017 mol) of cerium nitrate hexahydrate, and 7.0 g (0.034 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was found that the oxide film did not peel off and was in close contact with the stainless steel. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Example 6 (Zr+Ce+Si)/Al=0.15 Ce=0.005
Example 1 except that 5.3 g (0.02 mol) of zirconium oxynitrate dihydrate, 0.37 g (0.00085 mol) of cerium nitrate hexahydrate, and 1.2 g (0.0058 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was found that the oxide film did not peel off and was in close contact with the stainless steel. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Example 7 (Zr+Ce+Si)/Al=0.31 Si=0.005
Example 1 except that 5.5 g (0.02 mol) of zirconium oxynitrate dihydrate, 13.0 g (0.03 mol) of cerium nitrate hexahydrate, and 0.18 g (0.00086 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was found that the oxide film did not peel off and was in close contact with the stainless steel. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Example 8 Graphite The coating solution prepared in Example 1 was applied to a 100 mm x 50 mm graphite substrate degreased with acetone in the same manner as in Example 1, and sintered at 150° C. for 2 hours to form a 0.8 μm thick graphite substrate. A heat-resistant member was prepared by coating graphite with a colorless and transparent film.
As a result of measuring the weight loss when this heat-resistant member was heated from room temperature to 800° C. at a rate of 10° C./min, the weight was reduced by 20% compared to before heating.
From this, it was evaluated as having heat resistance.

Example 9 (film thickness 5 μm)
A 50 mm x 50 mm stainless steel (SUS304) substrate degreased with acetone was immersed in the coating solution prepared in Example 1 for 5 minutes in the same manner as in Example 1. Thereafter, the substrate was slowly pulled up, dried at 30°C for 2 hours, and then sintered at 150°C for 2 hours. This operation was repeated five times to produce a heat-resistant member in which stainless steel was coated with a colorless and transparent film having a thickness of 4.5 μm.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was found that the oxide film did not peel off and was in close contact with the stainless steel. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Example 10 (film thickness 25 μm)
The coating solution prepared in Example 1 was concentrated five times under reduced pressure, and in the same manner as in Example 1, a stainless steel (SUS304) substrate 50 mm x 50 mm degreased with acetone was immersed in the coating solution for 5 minutes. Thereafter, the substrate was slowly pulled up, dried at 30°C for 2 hours, and then sintered at 150°C for 2 hours. This operation was repeated five times to produce a heat-resistant member in which stainless steel was coated with a colorless and transparent film having a thickness of 25 μm.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was found that the oxide film did not peel off and was in close contact with the stainless steel. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Example 11 (1,500°C treatment)
The coating solution prepared in Example 1 was diluted twice, and in the same manner as in Example 1, a 50 mm x 50 mm stainless steel (SUS304) substrate degreased with acetone was immersed in the coating solution for 5 minutes. Thereafter, the substrate was slowly pulled up, dried at 30°C for 2 hours, and then sintered at 150°C for 2 hours. This operation was repeated several times to produce a heat-resistant member in which stainless steel was coated with a colorless and transparent film having a thickness of 1.2 μm.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. This heat-resistant member was heated from room temperature to 1,500°C at a rate of 10°C/min, held at 1,500°C for 24 hours, allowed to cool naturally, and then visually observed. No peeling of the oxide film was observed. It was stuck tightly to the stainless steel. In addition, the surface of the member treated at 1,500°C was magnified 30,000 times using a scanning electron microscope (FE-SEM: Hitachi High-Technologies S-4800), and the external diffusion of Cr ions was observed. As a result of observing the crystals derived from Cr ₂ O ₃ , no crystals derived from Cr ₂ O ₃ could be confirmed.
From this, it was evaluated as having heat resistance.

Comparative example 1 (Zr+Ce+Si)/Al=0.0076
Example 1 except that 0.081 g (0.0003 mol) of zirconium oxynitrate dihydrate, 0.16 g (0.0004 mol) of cerium nitrate hexahydrate, and 0.13 g (0.0006 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was confirmed that some of the oxide films had peeled off. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment (FIG. 2), crystals derived from Cr ₂ O ₃ were confirmed.
From this, it was evaluated as having no heat resistance.

Comparative example 2 (Zr+Ce+Si)/Al=0.6
Example 1 except that 6.4 g (0.024 mol) of zirconium oxynitrate dihydrate, 13.0 g (0.03 mol) of cerium nitrate hexahydrate, and 10.0 g (0.05 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was confirmed that some of the oxide films had peeled off. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, crystals derived from Cr ₂ O ₃ were confirmed.
From this, it was evaluated as having no heat resistance.

Comparative example 3 (Zr+Ce+Si)/Al=0.3 Ce=0.0005
Example 1 except that 5.6 g (0.02 mol) of zirconium oxynitrate dihydrate, 0.37 g (0.00085 mol) of cerium nitrate hexahydrate, and 6.2 g (0.03 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was confirmed that some of the oxide films had peeled off. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, crystals derived from Cr ₂ O ₃ were confirmed.
From this, it was evaluated as having no heat resistance.

Comparative example 4 (Zr+Ce+Si)/Al=0.3 Si=0.0005
Example 1 except that 5.6 g (0.02 mol) of zirconium oxynitrate dihydrate, 13.2 g (0.03 mol) of cerium nitrate hexahydrate, and 0.018 g (0.00085 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was confirmed that some of the oxide films had peeled off. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, crystals derived from Cr ₂ O ₃ were confirmed.
From this, it was evaluated as having no heat resistance.

Comparative example 5 (Zr+Ce+Si)/Al=0.3 Zr=0.0005
Example 1 except that 0.23 g (0.00085 mol) of zirconium oxynitrate dihydrate, 9.1 g (0.02 mol) of cerium nitrate hexahydrate, and 6.2 g (0.03 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was confirmed that some of the oxide films had peeled off. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, crystals derived from Cr ₂ O ₃ were confirmed.
From this, it was evaluated as having no heat resistance.

Comparative example 6 (film thickness 50 μm)
The coating solution prepared in Example 1 was concentrated five times under reduced pressure, and in the same manner as in Example 1, a stainless steel (SUS304) substrate 50 mm x 50 mm degreased with acetone was immersed in the coating solution for 5 minutes. Thereafter, the substrate was slowly pulled up, dried at 30°C for 2 hours, and then sintered at 150°C for 2 hours. This operation was repeated 10 times to produce a heat-resistant member in which stainless steel was coated with a colorless and transparent film having a thickness of 50 μm.
As a result of measuring the oxide film using an X-ray diffraction device, it was found to have a boehmite structure. When this heat-resistant member was visually observed after being treated at 1,000° C. in the same manner as in Example 1, it was confirmed that some of the oxide films had peeled off. Furthermore, as a result of SEM observation of the surface of the member after the aforementioned 1,000° C. treatment, crystals derived from Cr ₂ O ₃ were confirmed.
From this, it was evaluated as having no heat resistance.

Comparative Example 7 Graphite (Zr+Ce+Si)/Al=0.3 Zr=0.0005
Example 8 except that 0.23 g (0.00085 mol) of zirconium oxynitrate dihydrate, 9.1 g (0.02 mol) of cerium nitrate hexahydrate, and 6.2 g (0.03 mol) of tetraethoxysilane were used. operated in the same way.
As a result of measuring the weight loss when this member was heated from room temperature to 800° C. at a rate of 10° C./min, the weight was reduced by 60% compared to before heating.
From this, it was evaluated as having no heat resistance.

The adhesion of the oxide film of the coatings prepared in Examples 1 to 11 and Comparative Examples 1 to 7 after treatment at 1,000°C to 1,500°C, the presence or absence of crystals derived from Cr ₂ O ₃ and weight changes As a result of evaluating the heat resistance, it was confirmed that the coatings of Comparative Examples 1 to 7 exhibited peeling of the oxide film, generation of crystals derived from Cr ₂ O ₃ , or a 60% weight reduction, whereas in the present application The heat-resistant members of Examples 1 to 11, which are the coatings provided, had good adhesion, no crystals derived from Cr ₂ O ₃ were observed, and the weight reduction was 20%, so they were heat-resistant. showed that the performance was greatly improved.

By using the technology of the present invention, heat resistance can be imparted to members of various shapes, which is simple and inexpensive, and has a minimal effect on the appearance. Furthermore, due to the improved heat resistance of the parts, the durability time when used at high temperatures has also been significantly improved, and it can be used for gasket packing, circuits, electrode parts, etc. used in high-temperature oxidizing atmospheres. It is possible to contribute to the development of industry more broadly.
Furthermore, since the oxide film does not cause loss of conductivity, it can be used for electrode members, etc. Therefore, high heat resistance and durability can be provided as a conductive member.

Claims (4)

A heat-resistant member having a coating on its surface that satisfies all of the following (a) to (c): (a) made of oxides of aluminum, zirconium, cerium, and silicon; (b) atomic ratios of zirconium, cerium, and silicon to aluminum; satisfies all of the following (a) to (d) (atomic ratio)
Zr/Al=0.001 or more -(A)
Ce/Al=0.001 or more -(A)
Si/Al=0.001 or more -(C)
And (Si+Ce+Zr)/Al=0.01~0.5 -(D)
(c) Average film thickness of the coating is 0.01 to 30.0 μm The heat-resistant member according to claim 1, wherein the coating coats the surface of one or more of carbon or stainless steel having a melting point of 1,500° C. or higher. The heat-resistant heat-resistant material according to claim 1, wherein the aluminum oxide of the coating has at least one crystal form among amorphous, pseudoboehmite, boehmite, γ-alumina, θ-alumina, δ-alumina, and α-alumina. sex member A mixed solution consisting of an aluminum compound , a zirconia compound, a cerium compound, and a silicon compound is applied to the surface of carbon or stainless steel with a melting point of 1,500°C or higher , and after drying, heat treatment is performed at 100 to 1,500°C. The method for manufacturing a heat-resistant member according to claim 1 , 2, or 3, comprising: