JP7526452B2 - Coating material having inorganic coating, and manufacturing method and manufacturing device thereof - Google Patents

Description

The present invention relates to a coating material having a dense inorganic coating, and a manufacturing method and manufacturing device thereof.

Graphite (including carbon fiber/carbon composite materials) having excellent heat resistance has conventionally been used as a material for, for example, rocket combustion chambers and nozzles, or high-temperature heating furnaces for the production of semiconductors such as Si and the like, and for molten Al, and in order to improve its corrosion resistance (erosion resistance), various types of surface coatings are often applied to the graphite.
The following techniques are known as surface coating methods.

Patent Document 1 discloses a method of coating the inner surface of a graphite nozzle with carbide ceramics such as zirconium carbide (ZrC, melting point: about 3540° C.) or titanium carbide (TiC, melting point: about 3180° C.) by chemical vapor deposition (CVD) or a coating-firing process.
Patent Document 2 discloses a coating formed of any one of SiC, TiC, NbC, TaC, ZrC, and mixtures thereof on the entire surface of a graphite crucible for holding a quartz crucible for containing a Si source material in a Si crystal growth apparatus, and describes that the surface of the graphite crucible is covered with a carbide coating to prevent carbon evaporation, and the quartz crucible is coated with silicon nitride on the surface where the quartz crucible contacts the graphite crucible, thereby preventing a reaction between the carbide coating and quartz.
Patent Document 3 discloses a technique for forming a ZrC layer while heating the surface of an aluminum evaporation crucible to 1000° C. to 1400° C. by thermal CVD. Specifically, the zirconium raw material is chloride (ZrCl ₄ ), and hydrogen gas, argon gas, etc. are further supplied to form a Zr layer, which is then reacted with the carbon crucible base material to form a carbide (ZrC).
Patent Document 4 discloses a method for coating ZrC by plasma CVD. Specifically, a film is formed on a zircaloy substrate using a mixed gas of _ZrCl4 , _CH4 , and _H2 as raw material gas. At this time, in order to prevent corrosion of the substrate during film formation in a halogen atmosphere ( _ZrCl4 ), a protective layer is introduced on the substrate surface by sputtering.
Patent Document 5 discloses a heating furnace equipped with a core tube that houses a heater, characterized in that at least the inner surface of the core tube is made of one of TiC, ZrC, and HfC, and a manufacturing method thereof. Furthermore, in a heating furnace for _SiO2 material in an optical fiber drawing process or the like, in order to prevent deterioration of the inner surface of a carbon core tube, carbides of 4A group elements such as Ti, Zr, and Hf are preferable as high purity materials that have a lower vapor pressure than C at high temperatures and a lower reactivity with _SiO2 than C, and a carbon core tube having a coating layer of these by a CVD method is disclosed.

Silicon carbide (SiC) is known as a material suitable for use in corrosive environments at high temperatures. SiC has excellent high-temperature oxidation resistance because it forms a highly protective _SiO2 coating at high temperatures, but at temperatures above 1700°C, it is subject to significant thermal decomposition and mechanical strength loss, making it difficult to use SiC alone at temperatures above this range. For this reason, coating members that combine SiC and ZrC are known.
Non-Patent Document 1 discloses a technique for forming a film composed of ZrC and SiC on a Si substrate by a CVD method using ZrCl ₄ --CH ₄ --H ₂ --Ar as a raw material.
Furthermore, Non-Patent Document 2 discloses that a SiC film is formed on a C/C composite material by a CVD method using a Si source (MTS: CH ₃ SiCl ₃ ) and hydrogen gas, and then a ZrC film is formed by a CVD method using ZrCl ₄ , CH ₄ gas, and hydrogen gas, to form a multilayer structure.

Japanese Patent Application Publication No. 8-217575 Japanese Patent Application Publication No. 7-89789 Japanese Patent Application Publication No. 3-249172 Japanese Unexamined Patent Publication No. 62-80270 Japanese Patent Application Publication No. 10-338538

F. Wang et al., Ceram. Int. 43(2017) 2853-2858 Q. Liu et al., Surf. Coat. Technol. 205(2011) 4299-4303

The object of the present invention is to provide a coating material having a dense inorganic coating that has excellent adhesion to the substrate. Another object of the present invention is to provide a manufacturing method and manufacturing apparatus for a coating material that has the effect of reducing the environmental load.

The present inventors have investigated a coating material in which a substrate and an inorganic coating disposed on the surface thereof are integrated, and a manufacturing method thereof, for use in high-temperature parts used in aircraft or spacecraft, high-temperature parts related to nuclear power, heating furnaces, and the like, and have completed the present invention.
A coating material according to one aspect of the present invention (hereinafter also referred to as the "coating material of the first embodiment") comprises a substrate and an inorganic coating covering at least a portion of a surface of the substrate, the inorganic coating being characterized in that the inorganic coating is made of zirconium carbide having an oxygen content of 16 atomic % or less.
A method for producing a coating material according to one aspect of the present invention (hereinafter also referred to as the "production method of the first embodiment") is a method for producing a coating material according to the first embodiment, and is characterized in that a vaporized product of an organic compound containing zirconium atoms is allowed to reside on the surface of a substrate, and the vaporized product is irradiated with a laser having a power density of 60 W/ ^cm2 or more.
A coating material manufacturing apparatus according to one aspect of the present invention (hereinafter also referred to as the "first embodiment of the manufacturing apparatus") is characterized by comprising a film formation chamber in which a substrate is placed, a raw material gas supply means for supplying a vaporized product of an organic compound containing zirconium atoms into the film formation chamber, and a laser irradiation means for irradiating a laser onto a surface of the substrate.
A coating material according to another aspect of the present invention (hereinafter also referred to as the "coating material of the second embodiment") comprises a substrate and an inorganic coating covering at least a portion of a surface of the substrate, the inorganic coating being made of a composite material containing zirconium carbide and silicon carbide.
A method for producing a coating material according to another aspect of the present invention (hereinafter also referred to as the "second embodiment of the production method") is a method for producing a coating material according to the second embodiment, which is characterized in that a vaporized material of an organic compound containing zirconium atoms and a vaporized material of an organic compound containing silicon atoms are allowed to reside on the surface of a substrate, and these vaporized materials are irradiated with a laser.
A coating material manufacturing apparatus according to another aspect of the present invention (hereinafter also referred to as the "manufacturing apparatus of the second embodiment") is characterized in that it comprises a film formation chamber in which a substrate is placed, raw material gas supply means for supplying a mixture of a vaporized organic compound containing zirconium atoms and a vaporized organic compound containing silicon atoms into the film formation chamber, and laser irradiation means for irradiating a laser onto a surface of the substrate.

The coating material of the present invention is suitable for use as a high temperature component because it contains zirconium carbide, which has a melting point of about 3540°C.
The coating material manufacturing method and coating material manufacturing apparatus of the present invention do not require setting the entire inside of the film formation chamber to a high temperature, and can suppress film formation on the inner walls of the film formation chamber, which has traditionally been considered a problem with known CVD methods, and can form a dense inorganic coating with excellent adhesion in a predetermined position on the substrate, making them useful as a method and apparatus for reducing the environmental burden.

FIG. 1 is a schematic diagram showing an example of a production apparatus of the present invention. 1 shows X-ray diffraction patterns of the inorganic coatings obtained in Examples 1-1 to 1-3. 1 is an electron microscope image of the surface of the inorganic coating obtained in Example 1-1. 1 is an electron microscope image of a cross section (fracture surface) of the inorganic coating obtained in Example 1-1. 1 is an electron microscope image of the surface of the inorganic coating obtained in Example 1-3. 1 is an electron microscope image of a cross section (fracture surface) of the inorganic coating obtained in Example 1-3. 1 is an electron microscope image of a cross section (cross section after smoothing processing) of the inorganic coating obtained in Example 1-3. 1 is an X-ray diffraction pattern of the inorganic coating obtained in Example 1-4. 1 is an electron microscope image of a cross section (cross section after smoothing processing) of the inorganic coating obtained in Example 1-4. 1 is an electron microscope image of the surface of the inorganic coating obtained in Comparative Example 1-1. 1 is an electron microscope image of a cross section (fracture surface) of the inorganic coating obtained in Comparative Example 1-1. 1 is an electron microscope image of a cross section (cross section after smoothing processing) of the inorganic coating obtained in Comparative Example 1-1. 1 is an X-ray diffraction pattern of the inorganic coating obtained in Example 2-1. 1 is an electron microscope image of the surface of the inorganic coating obtained in Example 2-1. 1 is an electron microscope image of a cross section (fracture surface) of the inorganic coating obtained in Example 2-1. 1 is an electron microscope image of a cross section (cross section after smoothing processing) of the inorganic coating obtained in Example 2-1. This is a backscattered electron image reflecting the distribution of silicon atoms in the image of FIG. 17 is a backscattered electron image reflecting the distribution of zirconium atoms in the image of FIG. 16.

The coating material of the present invention is a composite having an inorganic coating on at least a portion of the surface of a substrate. The coating material of the first embodiment has an inorganic coating made of zirconium carbide having an oxygen content of 16 atomic % or less, and the coating material of the second embodiment has an inorganic coating made of a composite material containing zirconium carbide and silicon carbide.

The substrate in the coating material of the present invention is not particularly limited as long as it has heat resistance such that it does not melt or decompose at least at 1000° C., and further, does not react with zirconium carbide and silicon carbide at 1000° C. to 1300° C. The constituent material of the substrate is preferably an inorganic material (ceramics, metals, alloys, etc.), such as alumina (Al ₂ O ₃ ), YAG (Y ₃ Al ₅ O ₁₂ ), zirconia (ZrO ₂ ), silicon carbide (SiC), silicon nitride (Si ₃ N ₄ ), gallium nitride (GaN), silicon (Si), carbon, fiber-reinforced carbon composite material (C _f /C), fiber-reinforced SiC composite material (SiC _f /SiC), etc.

The shape of the substrate is not particularly limited and may be plate-like, linear, block-like, etc. The surface of the substrate having the inorganic coating may be either flat or curved, and further, this surface may be smooth or may have concave or convex portions.

The inorganic coating in the coating material of the first aspect of the present invention is made of zirconium carbide having an oxygen content of 16 atomic % or less. This zirconium carbide is generally represented as ZrC, but is not limited thereto, and the molar ratio of zirconium atoms to carbon atoms (C/Zr) is preferably 0.45 to 1.5, more preferably 0.65 to 1.1. The oxygen content in the inorganic coating made of zirconium carbide may be constant throughout or may vary in the cross-sectional direction. In the latter case, it is preferable that the oxygen content is 16 atomic % or less in all parts of the inorganic coating.
In the present invention, an inorganic coating containing ZrC with an oxygen content of more than 16 atomic % contains a component like an oxide of Zr, and the inorganic coating tends to have cracks. In addition, when a coating material having an inorganic coating with a high oxygen content is used and exposed to a high temperature atmosphere, further cracks are generated, which is not preferable. Since the inorganic coating in the coating material of the first aspect of the present invention is made of zirconium carbide with an oxygen content of 16 atomic % or less, such a defect does not occur and denseness is maintained.

In the coating material of the first aspect of the present invention, the thickness of the inorganic coating is preferably 10 nm or more, more preferably 1 μm to 10 mm, and even more preferably 5 μm to 100 μm, since the coating material is useful as a high-temperature component suitable for various applications.

The inorganic coating in the coating material of the second aspect of the present invention is made of a composite material containing zirconium carbide and silicon carbide. This composite material is not a material in which zirconium carbide and silicon carbide are unevenly distributed relative to each other, but a material in which these are contained in a uniformly mixed state. The zirconium carbide and silicon carbide may be either amorphous or crystalline, but it is preferable that both are crystalline.
The molar ratio (C/Zr) of zirconium atoms to carbon atoms constituting zirconium carbide is preferably 0.45 to 1.5, more preferably 0.65 to 1.1, and the molar ratio (C/Si) of silicon atoms to carbon atoms constituting silicon carbide is preferably 0.7 to 1.3, more preferably 0.9 to 1.1.

The content ratios of zirconium carbide and silicon carbide contained in the above composite material are not particularly limited, but since it is useful as a high-temperature component suitable for various applications, when the total of zirconium carbide and silicon carbide is 100 mol %, the content ratios are preferably 5 to 95 mol % and 5 to 95 mol %, more preferably 10 to 80 mol % and 20 to 90 mol %, and even more preferably 20 to 70 mol % and 30 to 80 mol %, respectively. The molar ratios of zirconium carbide and silicon carbide in the inorganic coating may be constant throughout the entire coating or may vary in the cross-sectional direction.

The composition of the composite material may contain oxygen atoms and nitrogen atoms in addition to zirconium atoms, silicon atoms, and carbon atoms. If the total atoms constituting the composite material are taken as 100%, the total proportion of zirconium atoms and silicon atoms is preferably 40 to 60%, more preferably 45 to 55%, and the proportion of carbon atoms is preferably 40% or more. In addition, if the composite material contains oxygen atoms, the proportion of oxygen atoms is preferably 15% or less.

In the coating material of the second aspect of the present invention, the thickness of the inorganic coating is preferably 10 nm or more, more preferably 1 μm to 10 mm, and even more preferably 5 μm to 100 μm, since it is useful as a high-temperature component suitable for various applications.

The manufacturing method of the first aspect of the present invention is characterized in that a vaporized material of an organic compound containing zirconium atoms (hereinafter referred to as a "zirconium atom-containing organic compound") is allowed to remain on the surface of a base material, and the vaporized material is irradiated with a laser having a power density of 60 W/ ^cm2 or more.

In the manufacturing method of the first aspect of the present invention, only a vaporized product of an organic compound containing zirconium atoms is used as a raw material gas. Conventionally, when an inorganic coating made of ceramics is manufactured by a known CVD method, a plurality of raw material components (halogen compounds, hydrocarbons, hydrogen, etc.) for forming ceramics have generally been used, but in the present invention, a zirconium carbide film can be formed using only one type of raw material component, i.e., an organic compound containing zirconium atoms.
In addition, the formation of the inorganic coating in the present invention is carried out in a closed space, as in conventional CVD. In the conventional method, when the above-mentioned multiple raw material components are mixed and reacted, the inner walls of the manufacturing equipment or the fixtures in the equipment are contaminated, but in the present invention, the substrate is locally heated and a coating is formed by laser irradiation, so that the above-mentioned problems are suppressed.

The zirconium atom-containing organic compound is not particularly limited as long as it vaporizes without decomposition at the boiling point. The zirconium atom-containing organic compound is preferably a compound containing carbon atoms, hydrogen atoms, and zirconium atoms, and more preferably a compound that vaporizes at a temperature of 20° C. to 250° C. In the present invention, a compound containing carbon atoms, hydrogen atoms, nitrogen atoms, and zirconium atoms is particularly preferred, and this compound is also preferred because it does not generate corrosive gases after vaporization.
The zirconium atom-containing organic compound containing carbon atoms, hydrogen atoms, nitrogen atoms and zirconium atoms is preferably tetrakis(alkylamido)zirconium represented by the general formula: Zr( _{NCnH2n + 1CmH2m +1} ) ₄ , where n is an integer of 1 to 5, and m is an integer of 1 to 5. Examples of this tetrakis(alkylamido)zirconium include tetrakis(ethylmethylamido)zirconium, tetrakis( _{dimethylamido} )zirconium, and tetrakis(diethylamido)zirconium, all of _which are represented by Zr( _NCH3C2H5 ) ₄ , and of these, tetrakis(ethylmethylamido)zirconium is preferred.

The method for preparing the vaporized product of the zirconium atom-containing organic compound is not particularly limited, and a conventionally known heating method, a vaporization method using a bubbling system, or the like can be applied.
The vaporized zirconium atom-containing organic compound used in the production method of the first embodiment may be of one type or of two or more types.

In the manufacturing method of the first embodiment, before the laser irradiation, the vaporized material of the zirconium atom-containing organic compound is allowed to remain on the surface of the substrate. The method of supplying the vaporized material is not particularly limited, and the film formation can be stably carried out by continuous or intermittent supply. When supplying the vaporized material, a method using a carrier gas (inert gas) and a method of fluidizing the vaporized material by evacuation can be mentioned. The supply rate of the vaporized material is preferably 5 to 2000 sccm, more preferably 10 to 200 sccm.
The manufacturing method of the first aspect is preferably a method of forming a film under reduced pressure conditions. The pressure inside the manufacturing apparatus during reduced pressure is preferably 20 to 10,000 Pa, more preferably 100 to 2,000 Pa. By reducing the pressure inside the manufacturing apparatus, preferably to 100 Pa or less, before supplying the vaporized material into the manufacturing apparatus, the effects of oxygen gas, moisture, etc. can be suppressed, and a coating material having an inorganic coating made of zirconium carbide with an oxygen content of 16 atomic % or less can be efficiently manufactured.

In the manufacturing method of the first aspect of the present invention, a vaporized zirconium-atom-containing organic compound is irradiated with a laser while the vaporized material is retained on the surface of the substrate. The laser to be used is not particularly limited, but a semiconductor laser, solid-state laser, gas laser, etc. with a wavelength of 100 to 10,800 nm can be used. The oscillation mode may be either continuous oscillation or pulse oscillation, but continuous oscillation is preferable. Preferred lasers include an excimer laser (wavelength: 193 to 351 nm), a Nd:YAG laser (wavelength: 1064 nm), a semiconductor laser using indium gallium arsenide phosphide or aluminum gallium arsenide (wavelength: 800 to 900 nm), a carbon dioxide laser (wavelength: 10.8 μm), a fiber laser (wavelength: 1604 nm), etc. Among these, a Nd:YAG laser and a semiconductor laser are preferable.

The power density of the laser irradiated to the vaporized product of the zirconium atom-containing organic compound is 60 W/cm ² or more, preferably 100 to 500 W/cm ² , and more preferably 110 to 200 W/cm ² , since a dense inorganic coating can be obtained. When a laser having such a power density is irradiated, the temperature of the film formation surface of the substrate is usually 1000° C. to 1300° C. The power density of the irradiated laser may be constant throughout or may be changed.

The laser irradiation time is appropriately selected depending on the area to be formed, the thickness of the inorganic coating, etc., but is usually 30 seconds to 60 minutes. When forming a large-area film, a method of irradiating the laser while scanning the laser with the substrate fixed or while changing the light path via a light diffusion lens, or a method of irradiating the laser with a fixed light path while moving the substrate, can be applied.

The atmosphere in which the laser is irradiated is preferably an inert gas atmosphere or vacuum in which the coexistence of gases containing oxygen atoms is suppressed. When an inert gas is used, argon, helium, nitrogen, etc. are preferred. When an inert gas atmosphere is used, the pressure is preferably 0.01 to 10,000 Pa, more preferably 20 to 10,000 Pa.

When irradiating with a laser, it is preferable to preheat the substrate from the viewpoint of efficient film formation. The preheating temperature is preferably 200°C or higher, and more preferably 400°C or higher. For example, preheating methods include a method using an infrared lamp, a halogen lamp, etc., and a method using resistance heating, high-frequency induction heating, microwave heating, etc.

When the vaporized zirconium-atom-containing organic compound is allowed to remain on the surface of the substrate and irradiated with a laser, the zirconium-atom-containing organic compound decomposes to produce zirconium carbide. Then, when the temperature rise reaches saturation, film formation begins, forming a dense inorganic coating made of zirconium carbide with an oxygen content of 16 atomic % or less.

The apparatus used in the manufacturing method of the first aspect of the present invention is not particularly limited.

The manufacturing method according to the second aspect of the present invention is characterized in that a vaporized material of an organic compound containing zirconium atoms (zirconium atom-containing organic compound) and a vaporized material of an organic compound containing silicon atoms (hereinafter referred to as "zirconium atom-containing organic compound") are allowed to remain on the surface of a substrate, and a laser is irradiated onto these vaporized materials.

In the manufacturing method of the second aspect of the present invention, a vaporized product of a zirconium atom-containing organic compound and a vaporized product of a silicon atom-containing organic compound are used. As the zirconium atom-containing organic compound, a compound that can be used in the manufacturing method of the first aspect can be used. The silicon atom-containing organic compound is not particularly limited as long as it vaporizes without decomposing at the boiling point, and is preferably a compound containing carbon atoms, hydrogen atoms, and silicon atoms, and more preferably a compound that vaporizes at a temperature of 20°C to 300°C.
Examples of silicon-containing organic compounds containing carbon atoms, hydrogen atoms, and silicon atoms include linear silanes represented by the general formula Si _n H _m (C _a H _2a+1 ) _(2n+2-m) (wherein a is an integer from 1 to 5, n is an integer from 1 to 10, and m is an integer from 1 to 10), and cyclic silanes represented by the general formula Si _j H _k (C _b H _2b+1 ) _(2j-1) (wherein b is an integer from 1 to 5, j is an integer from 1 to 10, and k is an integer from 1 to 10). These compounds are preferably used because they do not generate corrosive gases after vaporization. Examples of the silicon atom-containing organic compound include Si( _CH3 ) ₄ , _Si2 ( _CH3 ) ₆ (hexamethyldisilane _{), Si2H2(CH3)4, Si2(C2H5)6, C7Si3H22 , Si4 ( CH3 ) 8 , Si5H5 ( CH3 ) 5 , and " CVD} -4000" ₍ product name) manufactured by Starfire.

The method for preparing the vaporized product of the silicon-containing organic compound is not particularly limited, and a conventionally known heating method, a vaporization method using a bubbling system, or the like can be applied.
The vaporized silicon-containing organic compound used in the production method of the second embodiment may be of one type or of two or more types.

In the manufacturing method of the second embodiment, a mixture of a vaporized zirconium atom-containing organic compound and a vaporized silicon atom-containing organic compound is allowed to remain on the surface of the substrate before the laser irradiation. The method of supplying the mixture is not particularly limited, and film formation can be stably carried out by continuous or intermittent supply. When supplying the mixture, a method using a carrier gas (inert gas) and a method of fluidizing the mixture by evacuation can be mentioned. The supply rate of the mixture is preferably 5 to 2000 sccm, more preferably 10 to 200 sccm.
The second embodiment of the production method is preferably a method for producing a film under reduced pressure. The reduced pressure is preferably 20 to 10,000 Pa, more preferably 100 to 2,000 Pa.
In addition, as long as the vaporized material of the zirconium atom-containing organic compound and the vaporized material of the silicon atom-containing organic compound are mixed in a predetermined ratio on the surface of the substrate, these vaporized materials may be supplied separately to the surface of the substrate.

In the manufacturing method of the second aspect of the present invention, a mixture of a vaporized zirconium-atom-containing organic compound and a vaporized silicon-atom-containing organic compound is allowed to remain on the surface of a substrate, and the mixture is irradiated with a laser. There are no particular limitations on the laser used, and any laser that can be used in the manufacturing method of the first aspect can be applied.

The power density of the laser irradiated to the mixture of the vaporized zirconium atom-containing organic compound and the vaporized silicon atom-containing organic compound is 60 W/cm ² or more, preferably 80 to 500 W/cm ² , and more preferably 90 to 200 W/cm ² , in order to obtain a dense inorganic coating. The power density of the laser irradiated to the mixture may be constant throughout or may be varied.

The laser irradiation time is appropriately selected depending on the area to be formed, the thickness of the inorganic coating, etc., but is usually 30 seconds to 60 minutes.
The method of irradiating the laser, the atmosphere during laser irradiation, and preheating of the substrate can be the same as in the manufacturing method of the first embodiment.

When a mixture of vaporized zirconium-atom-containing organic compounds and vaporized silicon-atom-containing organic compounds is allowed to remain on the surface of a substrate and irradiated with a laser, the zirconium-atom-containing organic compounds decompose to produce zirconium carbide, and the silicon-atom-containing organic compounds decompose to produce silicon carbide, forming a dense inorganic coating in which these are uniformly mixed.

The apparatus used in the manufacturing method of the second aspect of the present invention is not particularly limited.

The manufacturing apparatus of the first aspect of the present invention includes a film formation chamber in which a substrate is placed, a raw material gas supply means for supplying a vaporized product of an organic compound containing zirconium atoms into the film formation chamber, and a laser irradiation means for irradiating a laser onto a surface of the substrate.
In addition, the manufacturing apparatus of the second aspect of the present invention includes a film formation chamber in which a substrate is placed, a raw material gas supply means for supplying a mixture of a vaporized material of a zirconium-atom-containing organic compound and a vaporized material of a silicon-atom-containing organic compound into the film formation chamber, and a laser irradiation means for irradiating a laser onto a surface of the substrate.

1 is a schematic diagram of a manufacturing apparatus of a second embodiment that can be used as the manufacturing apparatus of the first embodiment. That is, the manufacturing apparatus 1 of FIG. 1 includes a film forming chamber 2 in which a substrate 22 is placed, a raw material gas supplying means 6 for supplying raw material gas, and a laser irradiation means 4 (light source) for oscillating a laser on the surface of the substrate 22. The substrate 22 is placed on a substrate support table 14 that can preheat the substrate 22. When preheating the substrate 22, a heating resistor, a heating means using microwaves, an infrared lamp, a halogen lamp, or the like can be used. In addition, the substrate support table 14 can be provided with a function of rotating or moving the substrate 22 on its surface.
The inorganic coating is formed by irradiating the laser from the laser irradiation means 4 while the raw material gas supplied from the raw material gas supply means 6 is retained on the surface of the substrate 22. When the optical path of the laser is fixed, the substrate 22 on the substrate support stand 14 is irradiated with the laser while moving, and a large-area inorganic coating can be formed on the surface of the substrate 22. When the substrate 22 on the substrate support stand 14 is fixed, the substrate 22 is irradiated with the laser while scanning the laser or while changing the optical path via the light diffusion lens 16, and a large-area inorganic coating can be formed on the surface of the substrate 22. The material of the light diffusion lens 16 is appropriately selected depending on the type or wavelength of the laser, and examples of the material include quartz, BK7, and zinc selenide.

The raw material gas used in the manufacturing apparatus of the first embodiment is a vaporized zirconium-atom-containing organic compound, and the raw material gas used in the manufacturing apparatus of the second embodiment is a mixture of a vaporized zirconium-atom-containing organic compound and a vaporized silicon-atom-containing organic compound. Each vaporized material is prepared in the raw material gas preparation means 8, that is, in storage tanks 9 and 10 that separately store the raw material compounds before vaporization, by heating and vaporizing each raw material compound.

Preferred methods for supplying the raw material gas from the raw material gas supply means 6 to the deposition chamber 2 include a method using a carrier gas and a method of drawing a vacuum in the deposition chamber 2, and these methods can be combined.
1, a carrier gas supply means 26 may be provided upstream of the raw material gas preparation means 8. In addition, although not shown, a carrier gas supply means may be provided so as to be connected to the raw material gas supply means 6 before entering the deposition chamber 2.
When the film formation chamber 2 is evacuated, a pressure reducing means 12 may be connected to the film formation chamber 2 as shown in Fig. 1. A conventionally known vacuum pump or the like may be used as the pressure reducing means 12. In this case, it is preferable that the connection portion (raw material gas inlet) between the film formation chamber 2 and the raw material gas supply means 6, the substrate 22, and the pressure reducing means 12 are aligned in a straight line.

By utilizing the manufacturing method of the first aspect and the manufacturing method of the second aspect of the present invention, a composite coating material can be manufactured in which layers of zirconium carbide and mixed layers of zirconium carbide and silicon carbide are alternately arranged on the surface of a substrate.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples as long as they do not depart from the spirit of the present invention.

1. Raw Material Compound Tetrakisethylmethylaminozirconium (TEMAZ, model number: 553131-5G) manufactured by Aldrich was used as the zirconium atom-containing organic compound.
As the silicon atom-containing organic compound, "CVD-4000" (product name) manufactured by Starfire Corporation was used.

2. Substrate The following two types of substrate were used:
(1) A disk-shaped carbon substrate made by Sankyo Carbon Co., Ltd. The size was φ10 mm × 1 mm.
(2) Disk-shaped substrate made of alumina This was an alumina substrate (self-made) whose surface (film-forming surface) was mirror-polished, and its size was φ15 mm × 3 mm.

3. Production Apparatus In the following Examples 1-1 to 1-4, Example 2-1, and Comparative Example 1-1, a production apparatus 1 shown in FIG. 1 was used.
The manufacturing apparatus 1 of FIG. 1 includes a film-forming chamber 2 in which a substrate 22 is placed, a raw material gas supplying means 6 for supplying raw material gas into the film-forming chamber 2, and a laser irradiation means 4 for irradiating a laser onto the surface of the substrate 22. The vaporized material (raw material gas) supplied from the raw material gas supplying means 6 to the film-forming chamber 2 was prepared by heating raw material compounds (zirconium compounds or silicon compounds) with a heater 11 in storage tanks 9 and 10 that separately accommodate these compounds. In the following experimental example, a mixed gas containing argon gas and the raw material gas was supplied to the film-forming chamber 2 by a carrier gas supplying means 26. The laser irradiation means 4 was equipped with a light source that oscillates an Nd:YAG laser (wavelength: 1064 nm), and a lens 16 for focusing was arranged. The substrate 22 was placed on a heat-resistant support table 14 that was on the extension of the optical path of the laser emitted from the laser irradiation means 4 and was capable of preheating the substrate 22. The temperature during deposition on the surface of the substrate 22 by irradiating the laser was measured using a temperature measuring device 20. The inside of the deposition chamber 2 can be an inert gas atmosphere or reduced pressure, but in the following experimental example, an oil rotary vacuum pump was connected to the deposition chamber 2 as the decompression means 12.

4. Production and Evaluation of ZrC Film Example 1-1
Tetrakisethylmethylaminozirconium was placed in the zirconium atom-containing organic compound tank 9 and heated to 85°C to 105°C by the heater 11 to prepare a raw material gas. Then, the substrate 22 (carbon plate) was placed on the support table 14 preheated to 400°C, and the inside of the film-forming chamber 2 was made into a reduced pressure atmosphere, and the raw material gas was supplied to the film-forming chamber 2 together with argon gas (carrier gas) at a flow rate of 50 sccm. Then, a laser with a power density of 83 W/cm ² was irradiated onto the surface of the carbon substrate 22 for 10 minutes. The power density was calculated by dividing the output of the laser before it was incident on the light diffusion lens 16 and the window material 18 by the irradiation area. The temperature of the substrate surface during film formation was 1100°C, and the internal pressure of the film-forming chamber 2 was 300 Pa. After the supply of the raw material gas was stopped, the laser irradiation was terminated, the internal pressure of the film formation chamber 2 was reduced to 50 Pa or less (with the vacuum pump still running), the substrate surface temperature was reduced to 400° C. or less, and then the vacuum pump was stopped, and (after the film formation chamber 2 was opened to atmospheric pressure) the substrate with the inorganic coating was removed from the film formation chamber 2. The thickness of the obtained inorganic coating was 35 μm, and the film formation speed calculated from this thickness and the film formation time was 210 μm/hour.
The obtained inorganic coating was subjected to X-ray diffraction measurement and found to be amorphous (see FIG. 2). Furthermore, the composition of the inorganic coating was analyzed by EDX and found to be ZrC _0.86 containing 14 atomic % oxygen and 1.8 atomic % nitrogen as impurity components. Furthermore, the surface and cross section (fracture surface) of the inorganic coating were observed with a JEOL Ltd. scanning electron microscope "JSM-IT300HR/LV" (model name), and the images shown in FIG. 3 and FIG. 4 were obtained, respectively. From FIG. 4, it can be seen that the dense inorganic coating is in close contact with the substrate.

Example 1-2
An inorganic coating was obtained by the same operation as in Example 1-1, except that the power density of the laser was 116 W/cm ^2. The temperature of the substrate surface during the film formation was 1180° C. The thickness of the inorganic coating was 6.6 μm, and the film formation speed was 40 μm/hour.
The obtained inorganic coating was subjected to X-ray diffraction measurement and found to be cubic ZrC (see FIG. 2). The composition of the inorganic coating was ZrC _0.71 containing 3.2 atomic % oxygen and 2.2 atomic % nitrogen as impurity components. Furthermore, a cross-sectional observation of the inorganic coating revealed that the dense inorganic coating was in close contact with the substrate (not shown).

Examples 1-3
An inorganic coating was obtained by the same operation as in Example 1-1, except that the power density of the laser was 142 W/cm ^2. The temperature of the substrate surface during the film formation was 1270° C. The thickness of the inorganic coating was 14.3 μm, and the film formation speed was 86 μm/hour.
The obtained inorganic coating was subjected to X-ray diffraction measurement and found to be cubic ZrC (see FIG. 2). The composition of the inorganic coating was ZrC _0.81 , which contained 6.9 atomic % oxygen and 1.6 atomic % nitrogen as impurity components. Furthermore, the surface and cross section (fracture surface and cross section after smoothing by ion milling) of the inorganic coating were observed with a scanning electron microscope, and images of FIG. 5 (surface), FIG. 6 (fracture surface) and FIG. 7 (cross section after smoothing) were obtained. From FIG. 6 and FIG. 7, it can be seen that the dense inorganic coating is in close contact with the substrate.

Examples 1-4
Except for using an alumina plate instead of a carbon plate as the substrate 22 and changing the power density of the laser to 114 W/ ^cm2 , the same operation as in Example 1-1 was carried out (however, the film formation time was 5 minutes) to obtain an inorganic coating. The temperature of the substrate surface during film formation was 1230°C. The thickness of the inorganic coating was 4.7 μm, and the film formation speed was 56.4 μm/hour.
The obtained inorganic coating was subjected to X-ray diffraction measurement and found to be cubic ZrC (see FIG. 8). The composition of the inorganic coating was ZrC _0.47 , containing 4.5 atomic % oxygen and 1.6 atomic % nitrogen as impurity components. Furthermore, the cross section of the inorganic coating (cross section after smoothing by ion milling) was observed with a scanning electron microscope, and the image shown in FIG. 9 was obtained. It can be seen from FIG. 9 that the dense inorganic coating is in close contact with the substrate.

Comparative Example 1-1
An inorganic coating was obtained by the same operation as in Example 1-1, except that the power density of the laser was set to 51 W/ ^cm2 . The temperature of the substrate surface during the film formation was 965° C. The thickness of the inorganic coating was 3.5 μm, and the film formation speed was 21 μm/hour.
The obtained inorganic coating was subjected to X-ray diffraction measurement and found to be amorphous (not shown). In addition, the composition of the inorganic coating had a molar ratio of C atoms to Zr atoms of 0.42, and contained 18 atomic % oxygen and 1.0 atomic % nitrogen as impurity components. Furthermore, the surface and cross section (fractured surface and cross section after smoothing by ion milling) of the inorganic coating were observed with a scanning electron microscope, and images of FIG. 10 (surface), FIG. 11 (fractured surface) and FIG. 12 (cross section after smoothing) were obtained. From FIG. 10 and FIG. 12, it can be seen that the cracks on the surface are prominent, and from FIG. 11, it can be seen that the inorganic coating contains many fine voids and is not dense.

5. Production of ZrC/SiC composite film Example 2-1
Tetrakisethylmethylaminozirconium (TEMAZ) was placed in the zirconium atom-containing organic compound storage tank 9, and heated to 85°C to 105°C by the heater 11 to prepare the first raw material gas. Meanwhile, CVD-4000 was placed in the silicon atom-containing organic compound storage tank 10, and heated to 65°C by the heater 11 to prepare the second raw material gas. Then, the substrate 22 (carbon plate) was placed on the support table 14 preheated to 400°C, and the inside of the film formation chamber 2 was made into a reduced pressure atmosphere. The first raw material gas was supplied to the film formation chamber 2 together with argon gas (carrier gas) at a flow rate of 60 sccm, and the second raw material gas was supplied to the film formation chamber 2 together with argon gas (carrier gas) at a flow rate of 40 sccm. Then, a laser with a power density of 96 W/cm ² was irradiated to the surface of the substrate 22 for 10 minutes. The temperature of the substrate surface during film formation was 1050°C. The thickness of the inorganic coating was about 50 μm, and the coating speed calculated from the coating time was 300 μm/hour.
When the obtained inorganic coating was subjected to X-ray diffraction measurement, diffraction peaks of cubic ZrC and hexagonal SiC appeared (see FIG. 13). In addition, when the composition of the inorganic coating was analyzed by EDX, the ZrC/SiC component ratio (molar ratio) was 22/78. Incidentally, it contained 0.9 atomic % oxygen and 1.4 atomic % nitrogen as impurity components. Furthermore, the surface and cross section (fracture surface and cross section after smoothing by ion milling) of the inorganic coating were observed by a scanning electron microscope, and images of FIG. 14 (surface), FIG. 15 (fracture surface) and FIG. 16 (cross section after smoothing) were obtained. From FIG. 15 and FIG. 16, it can be seen that the dense inorganic coating is in close contact with the substrate. In addition, in order to investigate the distribution of ZrC and SiC in the inorganic coating, element mapping processing was performed on the observation image of FIG. 16, and images of FIG. 17 and FIG. 18 were obtained. FIG. 17 is a backscattered electron image reflecting silicon atoms, and indicates that silicon atoms are present in the dotted white parts. Fig. 18 is a backscattered electron image reflecting zirconium atoms, and indicates the presence of silicon atoms in the dotted white areas. It can be seen from Figs. 17 and 18 that the inorganic coating is in a uniform mixture state of ZrC and SiC.

6. Summary Table 1 briefly shows the experimental results.
Comparative Example 1-1 is an example not included in the present invention, and the denseness of the inorganic coating was insufficient. On the other hand, Examples 1-1 to 1-4 and Example 2-1 are examples of the present invention, and a coating material having a dense and homogeneous inorganic coating was obtained.

The coating material of the present invention is suitable for use in high-temperature parts used in aircraft or spacecraft, high-temperature parts related to nuclear power, heating furnaces, and other high-temperature parts in various plants.

1: Manufacturing apparatus 2: Film formation chamber 4: Laser irradiation means 6: Raw material gas supply means 8: Raw material gas preparation means 9: Zirconium atom-containing organic compound storage tank 10: Silicon atom-containing organic compound storage tank 11: Heater 12: Pressure reduction means 14: Substrate support stand 16: Light diffusion lens 18: Window material 20: Temperature measuring device 22: Substrate 24: Mass flow controller 26: Carrier gas supply means

Claims (4)

A coating material used for high-temperature parts in aircraft or spacecraft, high-temperature parts related to nuclear power, or high-temperature parts in heating furnaces,
1. A coating material comprising a substrate and an inorganic coating covering at least a portion of a surface of the substrate, the substrate being made of alumina or carbon, and the inorganic coating being made of zirconium carbide having an oxygen content of 14 atomic % or less. The coating material according to claim 1, wherein the zirconium carbide is crystalline. A coating material used for high-temperature parts in aircraft or spacecraft, high-temperature parts related to nuclear power, or high-temperature parts in heating furnaces,
A coating material comprising a substrate and an inorganic coating covering at least a portion of a surface of the substrate, the substrate being made of alumina or carbon, and the inorganic coating being made of a composite material containing zirconium carbide and silicon carbide in a uniformly mixed state . The coating material according to claim 3, wherein the zirconium carbide is crystalline.

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