Ceramic laminate and method for manufacturing a ceramic laminate

Abstract

To solve a problem that coating of metal or metal compound is peeled off from a surface of silicon carbide or a crack occurs due to a thermal expansion difference under a severe environment in the prior art and anticorrosion function cannot be sufficiently exerted, and to provide a ceramic laminate and a method for manufacturing a ceramic laminate which can securely exert anticorrosion property .SOLUTION: A ceramic laminate 1 in which a silicon carbide layer 20, an intermediate layer 30 and a coating layer 40 are laminated on a substrate 10 in this order, and Young's modulus of the silicon carbide layer 20 is 300 GPa or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a ceramic laminate and a method for manufacturing a ceramic laminate. [Background technology]

[0002] Silicon carbide (SiC) and SiC / SiC fiber-reinforced composites are expected to be next-generation structural materials for nuclear reactors and geothermal power plants. While silicon carbide has excellent mechanical properties as a ceramic structural material, corrosion protection coatings are necessary when exposed to harsh environments such as radiation, high temperatures, and high-pressure water.

[0003] For example, Non-Patent Document 1 proposes a fuel cladding tube in which the surface of silicon carbide is coated with a metal such as chromium, or a metal compound such as chromium nitride or titanium nitride. According to the invention in Non-Patent Document 1, corrosion protection is achieved for the surface of silicon carbide. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] PJ Doyle, C. Ang, L. Snead, Y.Katoh, K.Terrani, SS Raiman, “Hydrothermal Corrosion of First-Generation Dual-Purpose Coatings on Silicon Carbide for Accident-Tolerant Fuel Cladding,” J.Nucl.Mater., 544 (2021). [Overview of the project] [Problems that the invention aims to solve]

[0005] However, the invention described in Non-Patent Document 1 may not be able to fully exhibit its corrosion protection function under high-temperature, high-pressure, water-corrosion environments (for example, the furnace environment of a light water reactor) because the difference in thermal expansion between the substrate and the outermost laminated film may cause the metal or metal compound coating to peel off from the silicon carbide surface or crack.

[0006] Therefore, the present invention aims to provide a ceramic laminate that can reliably exhibit corrosion resistance and a method for manufacturing a ceramic laminate. [Means for solving the problem]

[0007] To solve the above problems, the present invention has the following aspects. [1] A silicon carbide layer, an intermediate layer, and a coating layer are stacked on the substrate in this order. A ceramic laminate in which the Young's modulus of the silicon carbide layer is 300 GPa or more. [2] The ceramic laminate according to [1], wherein the material constituting the coating layer is an aluminum oxide. [3] The ceramic laminate according to [1] or [2], wherein the material constituting the intermediate layer is an oxide containing silicon and aluminum. [4] The ceramic laminate according to any one of [1] to [3], wherein the sum of the thickness of the silicon carbide layer, the thickness of the intermediate layer, and the thickness of the coating layer is 100 μm or less. [5] The material constituting the intermediate layer contains silicon and aluminum, A ceramic laminate according to any one of [1] to [4], wherein the atomic ratio of aluminum / silicon is 1.0 to 15.

[0008] [6] A method for manufacturing a ceramic laminate, comprising stacking a silicon carbide layer, an intermediate layer, and a coating layer on a substrate in this order, A method for manufacturing a ceramic laminate, comprising contacting a silicon carbide raw material vapor onto a substrate in the presence of hydrogen gas to form the silicon carbide layer. [7] The method for manufacturing a ceramic laminate according to [6], wherein the time for laminating the intermediate layer is 10 to 150 seconds. [Effects of the Invention]

[0009] According to the ceramic laminate and method for manufacturing the ceramic laminate of the present invention, corrosion resistance can be reliably achieved. [Brief explanation of the drawing]

[0010] [Figure 1] This is a cross-sectional view showing a ceramic laminate according to one embodiment of the present invention. [Figure 2] This is a schematic diagram of the CVD apparatus used in the manufacturing of the ceramic laminate according to this embodiment. [Figure 3] This is an optical microscope image of the cross-section of Example 1. [Figure 4] This graph shows an example of a load-displacement curve used when measuring Young's modulus. [Figure 5] This is a schematic diagram showing a flat punch indenter and a small test specimen used in adhesion testing. [Figure 6] This is a scanning electron microscope (SEM) image of a microscopic test specimen used in adhesion testing. [Figure 7] This is a photograph showing the appearance of Example 1 after the corrosion test. [Figure 8] This is a scanning electron microscope (SEM) image of the cross-section of Comparative Example 1. [Figure 9] This is a photograph showing a partial enlargement of Figure 8. [Figure 10] This is a scanning electron microscope (SEM) image of the cross-section of Comparative Example 2. [Figure 11] This is an optical microscope image of the surface of the coating layer of Comparative Example 3 before the corrosion test. [Figure 12] This is an optical microscope image of the surface of the coating layer of Comparative Example 3 after the corrosion test. [Figure 13] This is a photograph showing the appearance of Comparative Example 4 after the corrosion test. [Modes for carrying out the invention]

[0011] [Ceramic Laminate] The ceramic laminate of the present invention comprises a silicon carbide layer, an intermediate layer, and a coating layer on a substrate in this order. The Young's modulus of the silicon carbide layer of the ceramic laminate of the present invention is 300 GPa or more. Hereinafter, one embodiment of the ceramic laminate of the present invention will be described with reference to the drawings.

[0012] As shown in Figure 1, the ceramic laminate 1 of this embodiment comprises a silicon carbide layer 20, an intermediate layer 30, and a coating layer 40 on a substrate 10 in this order. The ceramic laminate 1 can be used as a core material or fuel material in areas with stringent material requirements, such as next-generation light water reactors, small modular reactors, and reduced-speed reactors.

[0013] The thickness T1 of the ceramic laminate 1 is preferably 200 μm or more, and more preferably 600 μm or more. If the thickness T1 is above the lower limit, the strength of the ceramic laminate 1 can be further increased. The upper limit of the thickness T1 is not particularly limited, but is, for example, 1000 mm. The thickness T1 of the ceramic laminate 1 can be determined, for example, by observing a cross-section of the ceramic laminate 1 cut in the thickness direction using a microscope or the like.

[0014] <Circuit board> The substrate 10 can be made of known materials, provided that it can be used under high temperatures (e.g., 1000°C or higher) and high pressures (e.g., 10 MPa or higher). As the material for the substrate 10, silicon carbide (SiC) and SiC / SiC fiber-reinforced composite materials are preferred because they can be used in locations with strict material requirements, such as under high temperature and high pressure, and because they can further improve adhesion with the silicon carbide layer 20.

[0015] Thickness T of substrate 10 10 For example, a thickness of 100 μm or more is preferred, and a thickness of 500 μm or more is more preferred. 10 If the thickness T is greater than or equal to the lower limit mentioned above, the strength of the ceramic laminate 1 can be further increased. 10 The upper limit is not particularly limited, but for example, it is set at 1000 mm. The thickness T of the substrate 10 10 is determined in the same manner as the thickness T1 of the ceramic laminate 1.

[0016] The Young's modulus (E 10 ) of the substrate 10 is preferably, for example, 100 GPa or more, more preferably 150 GPa or more, and even more preferably 200 GPa or more. When the Young's modulus (E 10 ) is at or above the above lower limit value, the strength of the ceramic laminate 1 can be further increased. Therefore, the anticorrosion property of the ceramic laminate 1 can be more surely exhibited. The upper limit value of the Young's modulus (E 10 ) is not particularly limited, but is, for example, 500 GPa. The Young's modulus (E 10 ) can be measured by the method described in the examples. The Young's modulus (E 10 ) can be adjusted according to the type, composition, and combination of the materials of the substrate 10.

[0017] The thermal expansion coefficient (linear expansion rate, α 10 ) of the material constituting the substrate 10 is preferably, for example, 0.1 to 5.5×10 -6 / K, more preferably 1.0 to 5.4×10 -6 / K, and even more preferably 3.0 to 5.0×10 -6 / K. When the thermal expansion coefficient (α​​​​​​​​​​​​​​​​​

[0019] Examples of vapors from silicon carbide raw materials (hereinafter also referred to as "SiC raw materials") include vaporized silicon atom-containing organic compounds and halogen compounds containing silicon atoms. The silicon atom-containing organic compound is not particularly limited as long as it vaporizes without decomposing at its boiling point. Preferred silicon atom-containing organic compounds are those containing carbon atoms, hydrogen atoms, and silicon atoms, and more preferably compounds that vaporize at 20-250°C (293-523K). Examples of silicon atom-containing organic compounds include Hydrodopolycarbosilane (CVD-4000, manufactured by Starfire Systems) and Hexamethyldisilane (C6H 18 Examples include Si2, and CVD-4000 is preferred. The method for preparing vaporized silicon atom-containing organic compounds is not particularly limited and includes conventionally known heating methods, bubbling vaporization methods, and the like.

[0020] Thickness T of silicon carbide layer 20 20 For example, the thickness T is preferably 20 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less. 20 If the above upper limit is below this value, the strength of the silicon carbide layer 20 can be further increased. In addition, thickness T 20 If the thickness T is below the above upper limit, the production efficiency of the ceramic laminate 1 can be further increased. 20 The lower limit is not particularly limited, but from the viewpoint of resistance to use under high temperature and high pressure, for example, 0.5 μm or more is preferred. Thickness T of silicon carbide layer 20 20 This can be determined in the same way as the thickness T1 of the ceramic laminate 1.

[0021] Young's modulus (E) of silicon carbide layer 20 20 The Young's modulus (E) is 300 GPa or higher, preferably 320 GPa or higher, and more preferably 340 GPa or higher. 20If the Young's modulus (E) is greater than or equal to the lower limit above, the strength of the ceramic laminate 1 can be further increased. Therefore, the corrosion resistance of the ceramic laminate 1 can be reliably demonstrated. 20 The upper limit of ) is not particularly limited, but for example, it is set at 500 GPa. Young's modulus (E 20 ) can be measured by the method described in the examples. Young's modulus (E 20 This can be adjusted by the density of the silicon carbide layer 20, that is, by the film deposition conditions when forming the silicon carbide layer 20.

[0022] Young's modulus (E) of silicon carbide layer 20 20 ) and the Young's modulus (E) of substrate 10 10 The absolute value of the difference between |E| and ) 20 -E 10 | is preferably 300 GPa or less, more preferably 100 GPa or less, and even more preferably 50 GPa or less. Absolute value |E 20 -E 10 If | is below the above upper limit, the adhesion between the substrate 10 and the silicon carbide layer 20 can be further improved.

[0023] E 20 / E 10 The ratio expressed as (E 20 / E 10 For example, the ratio (E) is preferably 0.5 to 2.7, more preferably 0.6 to 1.5, and even more preferably 0.9 to 1.1. 20 / E 10 If the above values ​​are within the specified range, the adhesion between the substrate 10 and the silicon carbide layer 20 can be further improved. Therefore, the corrosion resistance of the ceramic laminate 1 can be more reliably demonstrated.

[0024] The material constituting the silicon carbide layer 20, i.e., the thermal expansion coefficient of silicon carbide (α 20 ) For example, 0.1 to 5.5 × 10 -6 / K is preferred, 1.0 to 5.4 × 10 -6 / K is more preferred, 3.0~5.0×10 -6 / K is even more preferable. Thermal expansion coefficient (α 20If the coefficient of thermal expansion (α) is greater than or equal to the lower limit above, the strength of the silicon carbide layer 20 can be further increased. 20 If the above upper limit is below this value, the adhesion with the intermediate layer 30 can be further improved. Thermal expansion coefficient (α 20 ) is the coefficient of thermal expansion (α 10 It can be calculated using the same method as above. Thermal expansion coefficient (α 20 This can be adjusted by the density of the silicon carbide layer 20, that is, by the film deposition conditions when forming the silicon carbide layer 20.

[0025] The thermal expansion coefficient of silicon carbide (α 20 ) and the thermal expansion coefficient of the substrate 10 (α 10 ) difference (α 20 -α 10 ) For example, 0.0 to 2.0 × 10 -6 / K is preferred, and 0.0 to 1.5 × 10 -6 / K is more preferable, 0.0~0.5×10 -6 / K is even more preferable. Difference (α 20 -α 10 If the difference (α) is greater than or equal to the lower limit above, the thermal shock resistance (strength against temperature changes) of the ceramic laminate 1 can be further improved. 20 -α 10 If the above upper limit is below this value, the adhesion between the substrate 10 and the silicon carbide layer 20 can be further improved.

[0026] <Middle class> The intermediate layer 30 is located between the silicon carbide layer 20 and the coating layer 40. The intermediate layer 30 is obtained by laminating the materials constituting the intermediate layer 30 using a chemical vapor deposition method. Examples of materials that make up the intermediate layer 30 include oxides containing silicon and aluminum. The materials constituting the intermediate layer 30 may be one type alone or two or more types in combination.

[0027] Examples of raw material vapors for the materials constituting the intermediate layer 30 include vaporized compounds containing silicon atom-containing organic compounds and aluminum atom-containing organic compounds, and mixed gases of silicon atom-containing halogen compounds and aluminum atom-containing halogen compounds. The vaporized product of a silicon atom-containing organic compound and an aluminum atom-containing organic compound is not particularly limited, as long as it vaporizes without decomposing at its boiling point. The aluminum atom-containing organic compound is preferably one containing carbon atoms, hydrogen atoms, and aluminum atoms, and more preferably one that vaporizes at 20-250°C (293-523K). Examples of aluminum atom-containing organic compounds include aluminum acetylacetonate (Al(CH3COCHCOCH3)3), tris(2,2,6,6-tetramethyl-3,5,3,5-heptanedionic acid)aluminum (Al(DPM)3), and trimethylaluminum, of which aluminum acetylacetonate is preferred. These compounds are also referred to as aluminum raw materials (hereinafter also called "Al raw materials"). Examples of silicon atom-containing organic compounds include CVD-4000, hexamethyldisilane, and tetraethyl orthosilicate (TEOS), of which CVD-4000 and TEOS are preferred. These compounds are also referred to as silicon raw materials (hereinafter also called "Si raw materials"), and may be the same as silicon carbide raw materials (SiC raw materials). The method for preparing vaporized products of a silicon atom-containing organic compound and an aluminum atom-containing organic compound is not particularly limited and can be conventionally known methods such as heating methods and bubbling vaporization methods.

[0028] When the material constituting the intermediate layer 30 contains silicon and aluminum, the atomic ratio expressed as aluminum / silicon (hereinafter also referred to as the "Al / Si ratio") is preferably 1.0 to 15, more preferably 2.0 to 8.0, and even more preferably 2.5 to 6.5. If the Al / Si ratio is above the lower limit, the adhesion with the coating layer 40 can be further improved. If the Al / Si ratio is below the upper limit, the adhesion with the silicon carbide layer 20 can be further improved. The Al / Si ratio can be determined, for example, by energy-dispersive X-ray spectroscopy (EDS).

[0029] Thickness T of the intermediate layer 30 30 For example, the thickness T is preferably 40 μm or less, more preferably 5 μm or less, and even more preferably 2 μm or less. 30 If the thickness T is greater than or equal to the lower limit mentioned above, the adhesion with the coating layer 40 can be further improved. 30 If the above upper limit is below this value, the strength of the intermediate layer 30 can be further increased. In addition, the thickness T 30 If the thickness T is below the above upper limit, the production efficiency of the ceramic laminate 1 can be further increased. 30 The lower limit is not particularly limited, but it is preferable to use a value of 0.1 μm or more, for example, as it can further improve adhesion with the coating layer 40. Thickness T of the intermediate layer 30 30 This can be determined in the same way as the thickness T1 of the ceramic laminate 1.

[0030] Young's modulus of the intermediate layer 30 (E 30 The Young's modulus (E) is preferably 150 GPa or higher, more preferably 175 GPa or higher, and even more preferably 200 GPa or higher. 30 If the Young's modulus (E) is greater than or equal to the lower limit above, the strength of the ceramic laminate 1 can be further increased. Therefore, the corrosion resistance of the ceramic laminate 1 can be more reliably demonstrated. 30 The upper limit of ) is not particularly limited, but for example, it is set at 250 GPa. Young's modulus (E 30 ) can be measured by the method described in the examples. Young's modulus (E 30) can be adjusted by the density of the intermediate layer 30, that is, the film formation conditions when forming the intermediate layer 30.

[0031] The Young's modulus (E 30 ) of the intermediate layer 30 and the Young's modulus (E 20 ) of the silicon carbide layer 20, the absolute value of the difference |E 30 - E 20 | is preferably, for example, 200 GPa or less, more preferably 180 GPa or less, and even more preferably 150 GPa or less. When the absolute value |E 30 - E 20 | is below the above upper limit value, the adhesion between the silicon carbide layer 20 and the intermediate layer 30 can be further enhanced.

[0032] E 30 / E 20 The ratio (E 30 / E 20 ) is preferably, for example, 0.40 to 1.00, more preferably 0.45 to 0.80, and even more preferably 0.50 to 0.70. When the ratio (E 30 / E 20 ) is within the above numerical range, the adhesion between the silicon carbide layer 20 and the intermediate layer 30 can be further enhanced. Therefore, the corrosion resistance of the ceramic laminate 1 can be more reliably exhibited.

[0033] The thermal expansion coefficient (α 30 ) of the material constituting the intermediate layer 30 is preferably not less than the thermal expansion coefficient (α 20 of silicon carbide and less than the thermal expansion coefficient (α ) of the material constituting the coating layer 40. More specifically, the thermal expansion coefficient (α 40 ) is preferably, for example, 3.0 to 7.0×10 30 / K, more preferably 3.5 to 6.5×10 -6 / K, and even more preferably 4.5 to 6.0×10 -6 / K. When the thermal expansion coefficient (α -6 ) is not less than the above lower limit value, the thermal shock resistance of the intermediate layer 30 can be further enhanced. When the thermal expansion coefficient (α 30 ) is below the above upper limit value, the adhesion with the silicon carbide layer 20 can be further enhanced. The thermal expansion coefficient (α 30 30) is obtained in the same manner as the coefficient of thermal expansion (α 10 ). The coefficient of thermal expansion (α 30 ) can be adjusted by the composition of the material constituting the intermediate layer 30, the film formation conditions when forming the intermediate layer 30, and combinations thereof.

[0034] The difference (α 30 ) between the coefficient of thermal expansion of the material constituting the intermediate layer 30 and the coefficient of thermal expansion of silicon carbide (α 20 ) (α 30 -α 20 ) is preferably 0.0 to 4.0×10 -6 / K, more preferably 0.0 to 3.5×10 -6 / K, and even more preferably 0.0 to 3.0×10 -6 / K. When the difference (α 30 -α 20 ) is not less than the above lower limit, the thermal shock resistance of the intermediate layer 30 can be further enhanced. When the difference (α 30 -α 20 ) is not more than the above upper limit, the adhesion between the silicon carbide layer 20 and the intermediate layer 30 can be further enhanced.

[0035] <Coating layer> The coating layer 40 is a top layer that coats the silicon carbide layer 20. The coating layer 40 is obtained by laminating the material constituting the coating layer 40 by chemical vapor deposition. By providing the coating layer 40, the ceramic laminate 1 can have higher resistance to use at high temperatures and high pressures. That is, the corrosion resistance can be further enhanced. Examples of the material constituting the coating layer 40 include metal oxides, and more specifically, alumina (aluminum oxide), zirconia (zirconium oxide), gallium oxide, magnesium oxide, calcium oxide, yttria (yttrium oxide), hafnia (hafnium oxide), etc. As the material constituting the coating layer 40, alumina is preferred because it has excellent corrosion resistance and can further enhance the adhesion to the intermediate layer 30. The material constituting the coating layer 40 may be used alone or in combination of two or more.

[0036] Examples of raw material vapors for the materials constituting the coating layer 40 include vaporized aluminum atom-containing organic compounds and aluminum atom-containing halogen compounds, and these raw materials are also called "Al raw materials". The aluminum atom-containing organic compound is not particularly limited as long as it vaporizes without decomposing at its boiling point. Preferably, the aluminum atom-containing organic compound is one that contains carbon atoms, hydrogen atoms, and aluminum atoms, and more preferably a compound that vaporizes at 20 to 250°C (293 to 523K). Examples of aluminum atom-containing organic compounds include aluminum acetylacetonate (Al(CH3COCHCOCH3)3), tris(2,2,6,6-tetramethyl-3,5,3,5-heptanedionic acid)aluminum (Al(DPM)3), and trimethylaluminum. Of these, aluminum acetylacetonate is preferred and may be the same as the Al raw material used in the preparation of the intermediate layer 30. From the viewpoint of simplifying the apparatus, it is preferable that the Al raw material used in the preparation of the intermediate layer 30 and the Al raw material used in the preparation of the coating layer 40 are of the same type. The method for preparing the vaporized aluminum atom-containing organic compound is not particularly limited and includes conventionally known heating methods, bubbling vaporization methods, and the like.

[0037] Thickness T of the coating layer 40 40 For example, the thickness T is preferably 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. 40 If the thickness T is below the above upper limit, the adhesion with the intermediate layer 30 can be further improved. 40 The lower limit is not particularly limited, but it is preferable, for example, to use a value of 1.0 μm or higher, as this can further enhance corrosion resistance. Thickness T of the coating layer 40 40 This can be determined in the same way as the thickness T1 of the ceramic laminate 1.

[0038] Young's modulus of coating layer 40 (E 40The Young's modulus (E) is preferably 180 GPa or higher, more preferably 200 GPa or higher, and even more preferably 300 GPa or higher. 40 If the Young's modulus (E) is greater than or equal to the lower limit above, the strength of the ceramic laminate 1 can be further increased. Therefore, the corrosion resistance of the ceramic laminate 1 can be more reliably demonstrated. 40 The upper limit of ) is not particularly limited, but for example, it is set at 500 GPa. Young's modulus (E 40 ) can be measured by the method described in the examples. Young's modulus (E 40 The density of the coating layer 40 can be adjusted by the type of material constituting the coating layer 40, the composition of the material constituting the coating layer 40, the film formation conditions when forming the coating layer 40, and combinations thereof.

[0039] Young's modulus of coating layer 40 (E 40 ) and the Young's modulus of the intermediate layer 30 (E 30 The absolute value of the difference between |E| and ) 40 -E 30 | is preferably 250 GPa or less, more preferably 200 GPa or less, and even more preferably 140 GPa or less. Absolute value |E 40 -E 30 If | is below the above upper limit, the adhesion between the intermediate layer 30 and the coating layer 40 can be further improved.

[0040] E 40 / E 30 The ratio expressed as (E 40 / E 30 For example, the ratio (E) is preferably 0.8 to 2.5, more preferably 1.2 to 2.0, and even more preferably 1.5 to 1.7. 40 / E 30 If the above values ​​are within the specified range, the adhesion between the intermediate layer 30 and the coating layer 40 can be further improved. Therefore, the corrosion resistance of the ceramic laminate 1 can be more reliably demonstrated.

[0041] The thermal expansion coefficient (α) of the material constituting the coating layer 40 40 ) is the thermal expansion coefficient of silicon carbide (α 20 ) is 2.0 × 10-6 It is preferable that the coefficient of thermal expansion (α) is greater than or equal to / K. More specifically, the coefficient of thermal expansion (α) 40 ) For example, 6.0~15×10 -6 / K is preferred, 6.0~10×10 -6 / K is more preferred, 6.0~8.0×10 -6 / K is even more preferable. Thermal expansion coefficient (α 40 If the coefficient of thermal expansion (α) is greater than or equal to the lower limit above, the thermal shock resistance of the coating layer 40 can be further improved. 40 If the above upper limit is below this value, the adhesion with the intermediate layer 30 can be further improved. Thermal expansion coefficient (α 40 ) is the coefficient of thermal expansion (α 10 It can be calculated using the same method as above. Thermal expansion coefficient (α 40 The characteristics can be adjusted by the type of material constituting the coating layer 40, the composition of the material constituting the coating layer 40, the film formation conditions when forming the coating layer 40, and combinations thereof.

[0042] The thermal expansion coefficient (α) of the material constituting the coating layer 40 40 ) and the thermal expansion coefficient (α) of the material constituting the intermediate layer 30. 30 ) difference (α 40 -α 30 ) is, for example, 0.0 × 10 -6 super 10×10 -6 Preferably less than / K, and 0.0 × 10 -6 Super 6.0×10 -6 / K or less is more preferable, 0.0 × 10 -6 Super 2.0×10 -6 A value of / K or less is even more preferable. Difference (α 40 -α 30 If the difference (α) exceeds the lower limit above, the thermal shock resistance of the coating layer 40 can be further improved. 40 -α 30 If the above upper limit is below this value, the adhesion between the intermediate layer 30 and the coating layer 40 can be further improved.

[0043] In the ceramic laminate 1, the thickness T of the silicon carbide layer 20. 20 And the thickness T of the intermediate layer 30 30 And the thickness T of the coating layer 40 40The sum of (T 20 +T 30 +T 40 The thickness (T) is preferably 100 μm or less, more preferably 80 μm or less, and even more preferably 60 μm or less. 20 +T 30 +T 40 If the total thickness (T) is below the above upper limit, the occurrence of delamination and cracking between layers can be suppressed, and corrosion resistance can be more reliably achieved. 20 +T 30 +T 40 The lower limit of ) is not particularly limited, but for example, 2.0 μm or more is preferred because it can further enhance corrosion resistance. Total thickness (T 20 +T 30 +T 40 ) is determined in the same way as the thickness T1 of the ceramic laminate 1.

[0044] [Method for manufacturing ceramic laminates] The present invention provides a method for manufacturing a ceramic laminate, which involves stacking a silicon carbide layer, an intermediate layer, and a coating layer on a substrate in that order. As a method for laminating these layers, chemical vapor deposition (CVD) is preferred because it can increase the density of each layer and further enhance corrosion resistance, and laser CVD, which performs CVD while irradiating with a laser, is even more preferred. The following describes a manufacturing method for the ceramic laminate 1 of this embodiment, specifically a method using laser CVD.

[0045] First, prepare a substrate (base material) 10. The substrate 10 is not particularly limited, but it is preferable to use a SiC sintered body obtained by sintering silicon carbide at 1800°C or higher. Furthermore, it is preferable to polish the surface of the substrate 10. Polishing the surface of the substrate 10 makes it easier to laminate the silicon carbide layer 20. When polishing the surface of the substrate 10, for example, #1200 grit waterproof sandpaper can be used. An example of equipment used in the laser CVD method is the cold-wall type laser CVD apparatus shown in Figure 2.

[0046] As shown in Figure 2, the CVD apparatus 100 includes a dome-shaped cold wall 110, a raw material supply unit 120, a laser irradiation unit 130, and a stage 140. The stage 140 is supported by a support base 142.

[0047] The laser irradiated from the laser irradiation unit 130 is not particularly limited, and semiconductor lasers, solid-state lasers, gas lasers, etc., can be used. One type may be used alone, or two or more types may be used in combination. Furthermore, the oscillation mode is not limited; it can be continuous oscillation or pulsed oscillation, but continuous oscillation is preferred. The wavelength of the emitted laser light is also not limited, but is typically 100 to 10800 nm. Specific examples of lasers irradiated from the laser irradiation unit 130 include, for example, fiber lasers and Nd:YAG lasers (neodymium:yttrium aluminum garnet lasers, wavelength 1.064 μm). The irradiation intensity of the laser used for irradiation is preferably, for example, 20 to 500 W.

[0048] When irradiating the substrate 10 with a laser, it is preferable to preheat the substrate 10 beforehand. The temperature during preheating is preferably, for example, 550 to 750K, more preferably 600 to 700K, and even more preferably 650 to 700K. If the temperature during preheating is above the lower limit, it becomes easier to laminate the silicon carbide layer 20. If the temperature during preheating is below the upper limit, the deterioration of the substrate 10 can be suppressed. The substrate 10 can be preheated, for example, inside a heating furnace, a CVD furnace, or the like.

[0049] Next, the substrate 10 is placed on the stage 140 of the CVD apparatus 100. First, the silicon carbide layer 20 is laminated. When laminating the silicon carbide layer 20, the silicon carbide raw material vapor is supplied together with hydrogen (H2) gas from the raw material supply unit 120 into the cold wall 110. At the same time, the substrate 10 on the stage 140 is irradiated with a laser from the laser irradiation unit 130. By bringing the silicon carbide raw material vapor into contact with the substrate 10 in the presence of H2 gas, the purity of the silicon carbide in the silicon carbide layer 20 can be further increased. As a result, the Young's modulus (E) of the silicon carbide layer 20 is increased. 20 This can be further enhanced. This is thought to be because supplying H2 gas into the cold wall 110 suppresses the contamination of the silicon carbide raw material with impurities. Alternatively, an inert gas such as argon (Ar) or nitrogen (N2) may be supplied into the cold wall 110 along with the raw material vapor as a transport gas for the silicon carbide raw material vapor. By supplying the transport gas along with the silicon carbide raw material vapor and H2 gas into the cold wall 110, the homogeneity of the silicon carbide layer 20 can be enhanced.

[0050] The temperature at which the silicon carbide raw material (SiC raw material) is heated (SiC heating temperature) is preferably 300 to 410 K, more preferably 310 to 410 K, and even more preferably 320 to 400 K, for example, in the case of CVD-4000. If the SiC heating temperature is above the lower limit, the corrosion resistance of the ceramic laminate 1 can be further enhanced. If the SiC heating temperature is below the upper limit, the density of the silicon carbide layer 20 can be further enhanced. The SiC heating temperature can be measured using a thermometer (not shown) installed inside the heating furnace used to heat the SiC raw material.

[0051] Temperature when depositing the silicon carbide layer 20 (film formation temperature t) 20 The film deposition temperature is preferably 1000 to 1700K, more preferably 1100 to 1650K, and even more preferably 1200 to 1600K. 20 If the above lower limit is exceeded, the purity of the silicon carbide layer 20 can be further increased. Film deposition temperature t 20 If the value is below the above upper limit, the degradation of the substrate 10 can be suppressed. Film forming temperature t 20 This can be measured by a thermometer (not shown) installed inside the cold wall 110.

[0052] Pressure inside the cold wall 110 when stacking silicon carbide layers 20 (furnace pressure P) 20 For example, the internal furnace pressure P is preferably 10 to 5000 Pa, more preferably 50 to 2000 Pa, and even more preferably 100 to 1000 Pa. 20 If the above lower limit is exceeded, the deposition rate of the silicon carbide layer 20 can be increased. Furnace pressure P 20 If the value is below the above upper limit, the purity of silicon carbide in the silicon carbide layer 20 can be further increased. Furnace pressure P 20 This can be measured by a pressure gauge (not shown) installed inside the cold wall 110.

[0053] Time required to deposit the silicon carbide layer 20 (film formation time) 20 For example, the film deposition time is preferably 30 to 2000 seconds, more preferably 100 to 1500 seconds, and even more preferably 150 to 900 seconds. 20 If the value is above the lower limit mentioned above, a silicon carbide layer 20 of sufficient thickness can be obtained. Film deposition time 20 If the above upper limit is below this value, the production efficiency of the ceramic laminate 1 can be further increased. Here, the film deposition time 20 This refers to the time during which the vapor of the SiC raw material is supplied to the inside of the cold wall 110.

[0054] Next, the intermediate layer 30 is laminated. When laminating the intermediate layer 30, the vapors of the raw materials constituting the intermediate layer 30 are supplied from the raw material supply unit 120 to the inside of the cold wall 110 along with transport gas (inert gas such as Ar or N2) and oxygen (O2) gas. More specifically, the vapors of the Si raw material and the Al raw material are supplied from the raw material supply unit 120 to the inside of the cold wall 110 along with Ar gas and O2 gas. Simultaneously, a laser is irradiated from the laser irradiation unit 130 onto the substrate 10 on the stage 140. The Al / Si ratio in the intermediate layer 30 can be adjusted according to the amount of Al raw material and the amount of Si raw material supplied. The amount of Al raw material and the amount of Si raw material supplied can be adjusted by the heating temperature of each raw material and the flow rate of the transport gas used for bubbling.

[0055] The temperature at which the Al raw material is heated (Al heating temperature) is preferably 350 to 520 K, more preferably 380 to 500 K, and even more preferably 400 to 480 K, for example, in the case of aluminum acetylacetonate. If the Al heating temperature is above the lower limit, the Al / Si ratio in the intermediate layer 30 can be increased. If the Al heating temperature is below the upper limit, the Si ratio in the intermediate layer 30 can be increased. The Al heating temperature can be measured using a thermometer (not shown) installed inside the heating furnace used to heat the Al raw material.

[0056] The temperature at which the Si raw material is heated (Si heating temperature) is preferably 300 to 410 K, more preferably 310 to 400 K, and even more preferably 320 to 390 K, for example, in the case of CVD-4000. If the Si heating temperature is above the lower limit, the ratio of Si in the intermediate layer 30 can be increased. If the Si heating temperature is below the upper limit, the Al / Si ratio in the intermediate layer 30 can be increased. The Si heating temperature can be measured using a thermometer (not shown) installed inside the heating furnace used to heat the Si raw material.

[0057] Temperature when depositing the intermediate layer 30 (film deposition temperature t) 30The film deposition temperature is preferably 1000 to 1700K, more preferably 1050 to 1650K, and even more preferably 1100 to 1600K. 30 If the above lower limit is exceeded, the density of the intermediate layer 30 can be further increased. Film deposition temperature t 30 If the value is below the above upper limit, the deterioration of the silicon carbide layer 20 can be suppressed. Film forming temperature t 30 This can be measured by a thermometer (not shown) installed inside the cold wall 110.

[0058] Pressure inside the cold wall 110 when stacking the intermediate layer 30 (furnace pressure P) 30 For example, the internal furnace pressure P is preferably 10 to 5000 Pa, more preferably 50 to 2000 Pa, and even more preferably 100 to 1000 Pa. 30 If the above lower limit is exceeded, the film deposition rate of the intermediate layer 30 can be increased. Furnace pressure P 30 If the value is below the above upper limit, it is possible to suppress the inclusion of impurities in the raw materials of the intermediate layer 30. Furnace pressure P 30 This can be measured by a pressure gauge (not shown) installed inside the cold wall 110.

[0059] Time required to deposit the intermediate layer 30 (film deposition time) 30 For example, the film deposition time is preferably 10 to 150 seconds, more preferably 20 to 140 seconds, and even more preferably 30 to 130 seconds. 30 If the value is above the lower limit mentioned above, an intermediate layer 30 of sufficient thickness can be obtained. Film deposition time 30 If the above upper limit is below this value, the production efficiency of the ceramic laminate 1 can be further increased. In addition, the film deposition time 30 If the value is below the above upper limit, corrosion can be suppressed, and the strength of the intermediate layer 30 can be further increased. Here, the film deposition time 30 This means that the substrate is at a film formation temperature t 30 This refers to the time during which the steam of the raw materials constituting the intermediate layer 30 is supplied into the interior of the cold wall 110.

[0060] Next, the coating layer 40 is laminated. When laminating the coating layer 40, the vapor of the raw materials constituting the coating layer 40 is supplied from the raw material supply unit 120 to the inside of the cold wall 110 along with a transport gas (an inert gas such as Ar or N2) and O2 gas. More specifically, the vapor of the Al raw material is supplied from the raw material supply unit 120 to the inside of the cold wall 110 along with Ar gas and O2 gas. At the same time, a laser is irradiated from the laser irradiation unit 130 onto the substrate 10 on the stage 140. The temperature at which the Al raw material is heated (Al heating temperature) is preferably 350-520K, more preferably 380-500K, and even more preferably 400-480K, for example, in the case of aluminum acetylacetonate.

[0061] The temperature (film formation temperature t) when laminating the coating layer 40. 40 The film deposition temperature is preferably 1000 to 1700K, more preferably 1100 to 1650K, and even more preferably 1200 to 1600K. 40 If the above lower limit is exceeded, the density of the coating layer 40 can be further increased. Film formation temperature t 40 If the value is below the above upper limit, the deterioration of the intermediate layer 30 can be suppressed. Film forming temperature t 40 This can be measured by a thermometer (not shown) installed inside the cold wall 110.

[0062] Pressure inside the cold wall 110 when laminating the coating layer 40 (furnace pressure P) 40 For example, the internal furnace pressure P is preferably 10 to 5000 Pa, more preferably 50 to 2000 Pa, and even more preferably 100 to 1000 Pa. 40 If the above lower limit is exceeded, the film deposition rate of the coating layer 40 can be increased. Furnace pressure P 40 If the value is below the above upper limit, it is possible to suppress the inclusion of impurities in the raw materials of the coating layer 40. Furnace pressure P 40 This can be measured by a pressure gauge (not shown) installed inside the cold wall 110.

[0063] Time taken to deposit the coating layer 40 (film formation time)40 For example, the film deposition time is preferably 30 to 6000 seconds, more preferably 100 to 3000 seconds, and even more preferably 150 to 1500 seconds. 40 If the value is above the lower limit mentioned above, a coating layer 40 of sufficient thickness can be obtained. Film deposition time 40 If the above upper limit is below this value, the production efficiency of the ceramic laminate 1 can be further increased. Here, the film deposition time 40 This means that the substrate is at a film formation temperature t 40 This refers to the time during which the steam of the raw materials constituting the coating layer 40 is supplied to the inside of the cold wall 110.

[0064] Through the above process, a ceramic laminate 1 is obtained in which a silicon carbide layer 20, an intermediate layer 30, and a coating layer 40 are stacked on a substrate 10 in that order.

[0065] In this embodiment, the ceramic laminate 1 has a coating layer 40 formed on its surface, which further enhances its corrosion resistance. In this embodiment, the ceramic laminate 1 has an intermediate layer 30 formed between the silicon carbide layer 20 and the coating layer 40. This prevents the coating layer 40 from peeling off from the silicon carbide layer 20 or from cracking. Therefore, corrosion resistance can be reliably achieved. The ceramic laminate 1 of this embodiment has a Young's modulus (E) of the silicon carbide layer 20. 20 Because the ) is controlled within a specific range, delamination and cracking between layers can be suppressed. Therefore, corrosion resistance can be reliably achieved. The manufacturing method of the ceramic laminate in this embodiment involves contacting the silicon carbide raw material vapor onto the substrate in the presence of hydrogen gas, thereby suppressing the contamination of the silicon carbide raw material with impurities. As a result, the Young's modulus (E) of the silicon carbide layer 20 is reduced. 20 This further enhances the strength of the ceramic laminate 1. As a result, the corrosion resistance of the ceramic laminate 1 can be more reliably demonstrated. Since the manufacturing method of the ceramic laminate in this embodiment uses chemical vapor deposition, the density of each layer can be increased, and as a result, corrosion resistance can be further enhanced. Since the manufacturing method for the ceramic laminate in this embodiment uses the laser CVD method, each layer can be continuously laminated, thereby increasing production efficiency. Since the manufacturing method for the ceramic laminate in this embodiment uses laser CVD, the density of each layer can be increased, and the film deposition rate can be increased. As a result, the corrosion resistance of the ceramic laminate can be further enhanced, and production efficiency can be increased.

[0066] Although the ceramic laminate and method for manufacturing the ceramic laminate of the present invention have been described above, the present invention is not limited to the embodiments described above and can be modified as appropriate without departing from the spirit of the invention. For example, the ceramic laminate 1 described above has one intermediate layer 30, but the intermediate layer may consist of two or more layers. When two or more intermediate layers are provided, it is preferable to laminate the intermediate layers so that the Al / Si ratio of each intermediate layer is gradually increased. By laminating the intermediate layers so that the Al / Si ratio of each intermediate layer is gradually increased, the adhesion between the silicon carbide layer and the coating layer can be further improved. As a result, delamination and cracking between layers can be suppressed, and corrosion resistance can be reliably achieved. When laminating two intermediate layers, for example, the Al / Si ratio of the intermediate layer on the silicon carbide layer side can be set to 1.5 to 2.5, and the Al / Si ratio of the intermediate layer on the coating layer side can be set to 3.0 to 5.0. By laminating the intermediate layers with a gradient of Al / Si ratios in this way, the adhesion between the layers can be further improved. When laminating three intermediate layers, for example, the Al / Si ratio of the intermediate layer on the silicon carbide layer side can be set to 1.5-2.5, the Al / Si ratio of the middle intermediate layer to 6.0-8.0, and the Al / Si ratio of the intermediate layer on the coating layer side to 10-16. By laminating the intermediate layers with a gradient of Al / Si ratios in this way, the adhesion between layers can be further improved.

[0067] For example, the ceramic laminate 1 described above has one coating layer 40, but the coating layer may be two or more layers. By having two or more coating layers, corrosion resistance can be further enhanced. For example, although the ceramic laminate 1 described above has a coating layer 40 formed on its surface, the ceramic laminate may have other layers, such as a printed layer, further laminated on top of the coating layer. [Examples]

[0068] The present invention will be described in more detail below using examples, but the present invention is not limited to these examples.

[0069] [Example 1] Using the CVD apparatus 100 shown in Figure 2, a SiC sintered body was used as the substrate, and a SiC layer (underlayer), a layer composed of a mixture of silicon oxide and aluminum oxide (intermediate layer), and a layer composed of aluminum oxide (coating layer) were continuously laminated. The same Hydrodopolycarbosilane (CVD-4000, Starfire Systems) was used as the SiC raw material and Si raw material (hereinafter referred to only as the Si raw material). Aluminum acetylacetonate (Al(acac)3, Sigma Aldrich) was used as the Al raw material. First, a SiC substrate (10mm x 10mm) was prepared, ground with #1200 grit, and then preheated to 673K. This SiC substrate was placed on a stage 140 inside a cold wall 110, and Si raw material vapor (heating temperature of Si raw material is 353K) was supplied to the cold wall 110 from a raw material supply unit 120 along with H2 gas. A fiber laser (irradiation intensity 300W) was applied to the surface of the SiC substrate on the stage 140 for 480 seconds (film deposition time (time)). 20 The SiC layer was deposited by irradiating it with t 20 The temperature was set to 1533K, and the furnace pressure inside the cold wall 110 was set to 500Pa. Next, the heating temperature for the Al raw material is set to 438K and the heating temperature for the Si raw material is set to 353K. The vaporized materials of each raw material are supplied from the raw material supply unit 120 along with the transport gas (Ar gas) and O2 gas, and a fiber laser (irradiation intensity 150W) is applied to the surface of the SiC layer for 60 seconds (film deposition time (time) 30 The film was irradiated and an intermediate layer with an Al / Si ratio of 4.6 was deposited. Deposition temperature (t 30 The temperature was controlled to 1273-1373K, and the furnace pressure inside the cold wall 110 was set to 400Pa. Finally, Al raw material (heated to 438K) is supplied from the raw material supply unit 120 into the cold wall 110 along with transport gas (Ar gas) and O2 gas, and a fiber laser (irradiation intensity 200W) is applied to the intermediate layer surface for 720 seconds (film deposition time (time) 40 The film was irradiated and a coating layer was formed. Film formation temperature (t 40 The temperature was set to 1503K, and the furnace pressure inside the cold wall 110 was set to 400Pa. Through the above process, a ceramic laminate 1 was obtained in which a silicon carbide layer 20, an intermediate layer 30, and a coating layer 40 were stacked in that order on a substrate 10, as shown in Figure 1. A photograph of a cross-section of the obtained ceramic laminate 1 is shown in Figure 3.

[0070] As shown in Figure 3, it was confirmed that the silicon carbide layer 20, the intermediate layer 30, and the coating layer 40 are stacked on the substrate 10 in this order. Each layer was densely formed, and it was confirmed that no delamination or cracking occurred at the interfaces between the layers. X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDS) confirmed that the constituent material of the coating layer 40 is α-alumina (Al2O3).

[0071] <Measurement of Young's modulus> The Young's modulus of each layer was measured using the nanoindentation method in accordance with ISO 14577. The measurements were performed on the cross-section of the ceramic laminate 1 sample. The cross-section of the sample was prepared by cutting the ceramic laminate 1 in the thickness direction with a diamond wheel saw, and then polishing the cross-section using a cross-section polisher sample preparation device. Using fused silica as a standard material, the shape factor of a diamond indenter (Berkovich type) was calibrated. Using the calibrated diamond indenter, the sample was pressed down to a maximum load of 2000 μN in 2 seconds, held for 1 second, and then released in 2 seconds. This operation was performed at a total of 40 locations: two rows with 1 μm intervals in the in-plane direction of each layer, and 0.5 μm intervals in the thickness direction of each layer. Excluding four measurements at the interface where the Young's modulus differed significantly depending on the thickness of each layer, the average Young's modulus was calculated by averaging the measurements from the remaining 36 locations.

[0072] Figure 4 shows an example of a load-displacement curve when measuring Young's modulus. In Figure 4, F is the load, h is the displacement, and F max is the maximum load, h max is the maximum displacement, S is the slope of the tangent to the unloading curve at the maximum load, h r The above tangent line intersects with the horizontal axis, h p The intersection of the unloading curve and the horizontal axis (amount of plastic deformation), h c represents the contact depth. Here, h c This can be calculated using the following formula (1).

[0073]

number

[0074] In equation (1), ε is a constant relating to the shape of the indenter, and is 0.75 for a Berkovich-type indenter. The Young's modulus E of each layer is given by equations (2) to (4) below. S This is required.

[0075]

number

[0076]

number

[0077]

number

[0078] In equation (2), H is hardness, A p This represents the area of ​​contact projection. A p 24.56h c 2 It is given by. In formula (3), E r This represents the composite modulus of elasticity. In formula (4), ν i ν is the Poisson's ratio of the indenter. S The Poisson ratio of each layer, E i E is the Young's modulus of the indenter. S This represents the Young's modulus of each layer.

[0079] The Young's modulus (E) of the substrate 10 obtained by the measurement method described above. 10 The pressure was 360 GPa. The Young's modulus (E) of the silicon carbide layer 20. 20 The pressure was 345 GPa. The Young's modulus (E) of the intermediate layer 30. 30 The pressure was 200 GPa. The Young's modulus of coating layer 40 (E 40 The pressure was 300 GPa. Both values ​​are extremely high for a thin film, indicating that a dense film was formed.

[0080] Adhesion tests and corrosion tests were performed using the obtained ceramic laminate 1. Furthermore, even when using the same raw materials, different deposition conditions (deposition temperature, furnace pressure, etc.) will result in films (layers) with different compositions.

[0081] <Adhesion Test> Adhesion testing was evaluated by indentation (indentation speed: 5 nm / s) using a flat punch indenter (diameter 30 μm diamond indenter) mounted on a nanoindentation apparatus as shown in Figure 5. The test specimens used for adhesion testing were micro-specimens whose surfaces were processed with a focused ion beam (FIB) apparatus, as shown in Figure 6. In Figure 5, the cross-section of each layer is shown as the top surface (the cross-section of each layer is arranged in the y-axis direction). The average value of the shear strength at the interface of each layer, measured from the indentation load by the flat punch indenter, is used as an indicator of interface adhesion and is shown below. • Interface between SiC layer 20 and intermediate layer 30 in Figure 6: Average pressure of 500 MPa or more. • Interface between the intermediate layer 30 and the coating layer 40 in Figure 6: Average pressure of 500 MPa or more. The average shear strength of each interface obtained is comparable to or better than the in-plane shear strength of pure aluminum oxide, and is considered sufficient considering the intended application.

[0082] <Corrosion Test> The corrosion test was performed by immersing ceramic laminate 1 in water at 320°C, 11 MPa, and a dissolved oxygen concentration of 8 ppm for 72 hours. The results of the corrosion test are shown in Figure 7. Note that the variations in density in the photograph are due to the synthesis of multiple fields of view. As shown in Figure 7, in Example 1 to which the present invention was applied, the coating layer did not peel off even after the corrosion test, and no traces of corrosion were observed.

[0083] [Comparative Example 1] Using the CVD apparatus 100 shown in Figure 2, a SiC layer (underlayer) and a layer (coating layer) made of aluminum oxide were continuously laminated on a SiC sintered body as the substrate. The same Si and Al raw materials as in Example 1 were used. A SiC substrate similar to that in Example 1 was ground with #1200 grit and then preheated to 673K. This SiC substrate was placed on a stage 140 inside a cold wall 110, and Si raw material vapor (heating temperature of Si raw material is 326K) was supplied into the cold wall 110 from a raw material supply unit 120 along with a transport gas (Ar gas). An Nd:YAG laser (irradiation intensity 130W) was applied to the surface of the SiC substrate on the stage 140 for 180 seconds (film deposition time (time) 20 The SiC layer was deposited by irradiating it with t 20 The temperature was set to 1323K, and the furnace pressure inside the cold wall 110 was set to 200Pa. Next, Al raw material (heated to 438K), transport gas (Ar gas), and O2 gas are supplied from the raw material supply unit 120 into the cold wall 110, and an Nd:YAG laser (irradiation intensity 130W) is applied to the SiC layer surface for 180 seconds (film deposition time (time) 40The film was irradiated and a coating layer was formed. Film formation temperature (t 40 The temperature was set to 1323K, and the furnace pressure inside the cold wall 110 was set to 200Pa. Through the above process, a ceramic laminate was obtained in which a silicon carbide layer 20 and a coating layer 40 were stacked in that order on a substrate 10. Photographs of the cross-section of the obtained ceramic laminate are shown in Figures 8 and 9. As shown in Figures 8 and 9, cracks in the coating layer 40 and delamination between the silicon carbide layer 20 and the coating layer 40 were observed in the obtained ceramic laminate. X-ray analysis and energy-dispersive X-ray analysis (EDS) confirmed that the constituent material of the coating layer 40 is γ-alumina (Al2O3). The Young's modulus (E) of the substrate 10 obtained by the measurement method described above. 10 The pressure was 350 GPa. The Young's modulus (E) of the silicon carbide layer 20. 20 The pressure was 265 GPa. The Young's modulus of the coating layer 40 was (E 40 The pressure was 200 GPa.

[0084] [Comparative Example 2] Using the CVD apparatus 100 shown in Figure 2, a SiC layer (underlayer) and a layer (coating layer) made of aluminum oxide were continuously laminated on a SiC sintered body as the substrate. The same Si and Al raw materials as in Example 1 were used. A SiC substrate similar to that in Example 1 was ground with #1200 grit and then preheated to 673K. This SiC substrate was placed on a stage 140 inside a cold wall 110, and Si raw material vapor (heating temperature of Si raw material is 350K) was supplied into the cold wall 110 from a raw material supply unit 120 along with a transport gas (Ar gas). An Nd:YAG laser (irradiation intensity 85W) was applied to the surface of the SiC substrate on the stage 140 for 180 seconds (film deposition time (time) 20 The SiC layer was deposited by irradiating it with t 20 The temperature was set to 1323K, and the furnace pressure inside the cold wall 110 was set to 80Pa. Next, the heating temperature for the Al raw material is set to 438K and the heating temperature for the Si raw material is set to 350K. The vaporized materials of each raw material are supplied from the raw material supply unit 120 along with the transport gas (Ar gas) and O2 gas, and an Nd:YAG laser (irradiation intensity 90W) is applied to the surface of the SiC layer for 180 seconds (film deposition time (time) 30 The film was irradiated and an intermediate layer with an Al / Si ratio of 5.0 was deposited. Deposition temperature (t 30 The temperature was controlled to 1323K, and the furnace pressure inside the cold wall 110 was set to 200 Pa. Finally, Al raw material (heated to 438K), transport gas (Ar gas), and O2 gas are supplied from the raw material supply unit 120 into the cold wall 110, and an Nd:YAG laser (irradiation intensity 90W) is applied to the intermediate layer surface for 180 seconds (film deposition time (time) 40 The film was irradiated and a coating layer was formed. Film formation temperature (t 40 The temperature was set to 1323K, and the furnace pressure inside the cold wall 110 was set to 200Pa. Through the above process, a ceramic laminate was obtained in which a silicon carbide layer 20, an intermediate layer 30, and a coating layer 40 were stacked in that order on a substrate 10, as shown in Figure 1. A photograph of a cross-section of the obtained ceramic laminate is shown in Figure 10.

[0085] As shown in Figure 10, it was confirmed that the silicon carbide layer 20, the intermediate layer 30, and the coating layer 40 are stacked on the substrate 10 in this order. Each layer was densely formed, and it was confirmed that no delamination or cracking occurred at the interfaces between the layers. X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDS) confirmed that the constituent material of the coating layer 40 is γ-alumina (Al2O3). The Young's modulus (E) of the substrate 10 obtained by the measurement method described above. 10 The pressure was 350 GPa. The Young's modulus (E) of the silicon carbide layer 20. 20 The pressure was 265 GPa. The Young's modulus (E) of the intermediate layer 30. 30 The pressure was 175 GPa. The Young's modulus of coating layer 40 (E 40 The pressure was 200 GPa.

[0086] [Comparative Example 3] A ceramic laminate was obtained in the same manner as in Comparative Example 2, except that the irradiation intensity of the Nd:YAG laser was set to 95W when depositing the SiC layer, the irradiation intensity of the Nd:YAG laser was set to 110W when depositing the intermediate layer, the deposition time was set to 180 seconds, and the irradiation intensity of the Nd:YAG laser was set to 110W when depositing the coating layer. X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDS) confirmed that the constituent material of the coating layer 40 is γ-alumina (Al2O3). The Young's modulus (E) of the substrate 10 obtained by the measurement method described above. 10 The pressure was 350 GPa. The Young's modulus (E) of the silicon carbide layer 20. 20 The pressure was 268 GPa. The Young's modulus (E) of the intermediate layer 30. 30 The pressure was 213 GPa. The Young's modulus of the coating layer 40 was (E 40 The pressure was 195 GPa. A corrosion test was conducted using the obtained ceramic laminate. The results of the corrosion test are shown in Figures 11 and 12. Figure 11 is an optical microscope (100x magnification) photograph of the surface of the coating layer before the corrosion test. Figure 12 is an optical microscope (100x magnification) photograph of the surface of the coating layer after the corrosion test.

[0087] As shown in Figure 12, the Young's modulus (E) of the silicon carbide layer 20 20 However, in Comparative Examples 2 and 3, where the pressure was less than 300 GPa, the surface of the coating layer 40 corroded, and X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDS) confirmed that the constituent material of the coating layer 40 had changed to boehmite (AlOOH).

[0088] [Comparative Example 4] Using the CVD apparatus 100 shown in Figure 2, a SiC layer (underlayer) and a layer (coating layer) made of aluminum oxide were continuously laminated on a SiC sintered body as the substrate. The same Si and Al raw materials as in Example 1 were used. A SiC substrate similar to that in Example 1 was ground with #1200 grit and then preheated to 673K. This SiC substrate was placed on a stage 140 inside a cold wall 110, and Si raw material vapor (heating temperature of Si raw material is 333K) was supplied into the cold wall 110 from a raw material supply unit 120 along with a transport gas (Ar gas). A fiber laser (irradiation intensity 170W) was applied to the surface of the SiC substrate on the stage 140 for 300 seconds (film deposition time (time) 20 The SiC layer was deposited by irradiating it with t 20 The temperature was set to 1323K, and the furnace pressure inside the cold wall 110 was set to 400Pa. Next, the heating temperature for the Al raw material is set to 438K and the heating temperature for the Si raw material is set to 333K. The vaporized materials of each raw material are supplied from the raw material supply unit 120 along with the transport gas (Ar gas) and O2 gas, and a fiber laser (irradiation intensity 160W) is applied to the surface of the SiC layer for 180 seconds (film deposition time (time) 30 The film was irradiated and an intermediate layer with an Al / Si ratio of 5.6 was deposited. Deposition temperature (t 30 The temperature was controlled to 1323K, and the furnace pressure inside the cold wall 110 was set to 400Pa. Finally, Al raw material (heated to 438K), transport gas (Ar gas), and O2 gas are supplied from the raw material supply unit 120 into the cold wall 110, and a fiber laser (irradiation intensity 210-220W) is applied to the intermediate layer surface for 300 seconds (film deposition time (time) 40 The film was irradiated and a coating layer was formed. Film formation temperature (t 40 The temperature was set to 1423K, and the furnace pressure inside the cold wall 110 was set to 400Pa. Through the above process, a ceramic laminate was obtained in which a silicon carbide layer 20, an intermediate layer 30, and a coating layer 40 were stacked in that order on a substrate 10, as shown in Figure 1. X-ray diffraction (XRD) and energy-dispersive X-ray analysis (EDS) confirmed that the constituent material of the coating layer 40 is γ-alumina (Al2O3). The Young's modulus (E) of the substrate 10 obtained by the measurement method described above. 10 The pressure was 350 GPa. The Young's modulus (E) of the silicon carbide layer 20. 20The pressure was 265 GPa. The Young's modulus (E) of the intermediate layer 30. 30 The pressure was 210 GPa. The Young's modulus of the coating layer 40 was (E 40 The pressure was 300 GPa. A corrosion test was conducted using the obtained ceramic laminate. The results of the corrosion test are shown in Figure 13. Note that the variations in density in the photograph are due to the synthesis of multiple fields of view.

[0089] As shown in Figure 13, the Young's modulus (E) of the silicon carbide layer 20 20 However, in Comparative Example 4, which had a pressure of less than 300 GPa, cracks were observed in the coating layer, the coating layer peeled off, and the surface of the underlying SiC substrate was exposed.

[0090] As described above, it has been found that the ceramic laminate and the method for manufacturing the ceramic laminate of the present invention can reliably exhibit corrosion resistance. [Explanation of symbols]

[0091] 1...Ceramic laminate, 10...Substrate, 20...Silicon carbide layer, 30...Intermediate layer, 40...Coating layer, 100...CVD apparatus, 110...Cold wall, 120...Raw material supply unit, 130...Laser irradiation unit, 140...Stage, 142...Support base

Claims

1. A silicon carbide layer, an intermediate layer, and a coating layer are stacked on the substrate in this order. The Young's modulus of the silicon carbide layer is 300 GPa or more. The material constituting the aforementioned intermediate layer is a mixture of silicon oxide and aluminum oxide. The material constituting the aforementioned coating layer is a ceramic laminate, which is an aluminum oxide.

2. The ceramic laminate according to claim 1, wherein the sum of the thickness of the silicon carbide layer, the thickness of the intermediate layer, and the thickness of the coating layer is 100 μm or less.

3. The ceramic laminate according to claim 1 or 2, wherein the atomic ratio of aluminum to silicon is 1.0 to 15.

4. The ceramic laminate according to claims 1 to 3, wherein the atomic ratio value represented by aluminum / silicon is 4.

6.

5. The ceramic laminate according to claim 1, wherein the Young's modulus of the substrate is 100 GPa or more.

6. The ceramic laminate according to claim 1, wherein the ratio E20 / E10 of the Young's modulus of the silicon carbide layer to the Young's modulus of the substrate is 0.5 to 2.

7.

7. A method for manufacturing a ceramic laminate, comprising stacking a silicon carbide layer, an intermediate layer, and a coating layer on a substrate in this order, In the presence of hydrogen gas, the silicon carbide raw material vapor is brought into contact with the substrate to form the silicon carbide layer. The material constituting the aforementioned intermediate layer is a mixture of silicon oxide and aluminum oxide. A method for manufacturing a ceramic laminate, wherein the material constituting the coating layer is an aluminum oxide.

8. The method for manufacturing a ceramic laminate according to claim 7, wherein the time for laminating the intermediate layer is 10 to 150 seconds.

Images