Slurry for spraying and manufacturing method for spray coating using the same

Abstract

To reduce cracking in a spray coating formed using a slurry for spraying containing spray particles composed of an oxide containing aluminum.SOLUTION: A slurry for spraying contains spray particles composed of an oxide containing aluminum and a dispersion medium. The slurry for spraying satisfies a formula (1). In the formula (1), E represents a Young's modulus (unit: GPa) of the oxide at 25°C, α represents a linear thermal expansion coefficient (unit: ppm / K) of the oxide in a temperature range from 30°C to 600°C, and D90 represents a volume-based cumulative 90% diameter (unit:μm) of the spray particles.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a slurry for thermal spraying and a method for producing a thermal spray coating using the same. [Background technology]

[0002] Ceramic spray coatings are used in various applications depending on the characteristics of the ceramics that make them up. Patent Document 1 discloses that spray coatings obtained by spraying a spray powder made of a composite oxide containing aluminum and yttrium are suitable as protective coatings for semiconductor device manufacturing equipment members. Patent Document 2 discloses that alumina coatings are used as protective coatings for semiconductor device manufacturing equipment members, and that plasma spraying is one of the techniques for producing alumina coatings.

[0003] Ceramic spray coatings can also be formed by spraying a slurry containing spray particles. Patent Document 3 discloses that an insulating ceramic body is formed integrally with a solid electrolyte body by plasma spraying an insulating ceramic slurry containing insulating ceramics such as alumina and a solvent onto the solid electrolyte body. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-80954 A [Patent Document 2] Special Publication No. 2013-531135 [Patent Document 3] JP 2007-298490 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the course of conducting research into thermal spray coatings formed using a thermal spraying slurry containing thermal spray particles made of an oxide containing aluminum, the inventors discovered that cracks may occur in the thermal spray coating.

[0006] Therefore, an object of the present invention is to reduce cracks in a thermal spray coating formed using a thermal spray slurry containing thermal spray particles made of an oxide containing aluminum. [Means for solving the problem]

[0007] The present inventors have found that there are cases where the characteristics of an oxide containing aluminum are related to the occurrence of cracks in a thermal spray coating, and have also surprisingly found that a specific particle size of thermal spray particles made of an oxide containing aluminum is related to the occurrence of cracks in a thermal spray coating.

[0008] Therefore, one aspect of the present invention is a slurry for thermal spraying, comprising thermal spray particles made of an oxide containing aluminum and a dispersion medium, The slurry for thermal spraying has the following formula (1):

[0009]

number

[0010] Fulfilling In the above formula (1), E is the Young's modulus (unit: GPa) of the oxide at a temperature of 25°C, α is the linear thermal expansion coefficient of the oxide in the temperature range from 30° C. to 600° C. [unit: ppm / K], D90 is the volume-based cumulative 90% particle diameter of the spray particles [unit: μm]; This relates to a slurry for thermal spraying. Effect of the Invention

[0011] According to the present invention, it is possible to reduce cracks in a thermal spray coating formed using a thermal spray slurry that contains thermal spray particles made of an oxide that contains aluminum. [Brief description of the drawings]

[0012] [Figure 1] 1 is a digital microscope surface observation image of a thermal spray coating formed using the slurry for thermal spraying of Example 1 according to one embodiment of the present invention. [Diagram 2] 1 is a digital microscope surface observation image of a thermal spray coating formed using the thermal spray slurry of Comparative Example 1. [Diagram 3] 1 is a digital microscope surface observation image of a thermal spray coating formed using the thermal spray slurry of Comparative Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, the embodiments of the present invention will be described, but the present invention is not limited to the following embodiments and can be modified in various ways within the scope of the claims. The embodiments described in this specification can be arbitrarily combined to form other embodiments.

[0014] In this specification, "X to Y" is used to mean that the numerical values ​​(X and Y) written before and after it are included as the lower and upper limits, and means "X or more and Y or less." Furthermore, unless otherwise specified, the operation and measurement of physical properties are performed under the conditions of room temperature (20 to 25°C) and relative humidity of 40 to 50% RH.

[0015] As used herein, "A and / or B" is meant to include each of A and B, and combinations thereof.

[0016] <Slurry for thermal spraying> One aspect of the present invention is a slurry for thermal spraying, comprising thermal spray particles made of an oxide containing aluminum and a dispersion medium, The slurry for thermal spraying satisfies the following formula (1).

[0017]

number

[0018] In the above formula (1), E is the Young's modulus (unit: GPa) of the oxide at a temperature of 25°C, α is the linear thermal expansion coefficient of the oxide in the temperature range from 30° C. to 600° C. [unit: ppm / K], D90 is the volume-based cumulative 90% particle diameter of the spray particles [unit: μm]; This relates to a slurry for thermal spraying.

[0019] In this embodiment, when the slurry for thermal spraying satisfies the above formula (1), it is possible to reduce cracks in the thermal spray coating formed using the slurry for thermal spraying.

[0020] The reason for this is that the smaller the Young's modulus (E) at 25°C and the coefficient of linear thermal expansion (α) in the temperature range from 30°C to 600°C, the smaller the stress generated during thermal contraction, so it is presumed that the smaller the product of the Young's modulus (E) at 25°C and the coefficient of linear thermal expansion (α) in the temperature range from 30°C to 600°C, the less likely cracks will occur in the thermal spray coating. Although the details are unclear, the inventors have found that there is a strong correlation between the volume-based cumulative 90% particle size (D90) and the occurrence of cracks in the thermal spray coating, and that the larger the volume-based cumulative 90% particle size (D90), the less likely cracks will occur in the thermal spray coating. It is presumed that when the above (1) is satisfied, the synergistic effect of these factors significantly increases the effect of reducing cracks in the thermal spray coating. Note that this mechanism is based on speculation, and whether it is correct or not does not affect the technical scope of the present invention.

[0021] The calculated value of the left side of formula (1) is not particularly limited as long as it is less than 130. Examples of the range of the calculated value of the left side of formula (1) include 125 or less, 120 or less, 110 or less, 100 or less, 1 or more, 10 or more, 50 or more, 60 or more, 70 or more, 90 or more, 1 or more and less than 130, 10 or more and less than 130, 50 or more and less than 130, 60 or more and less than 130, 70 or more and less than 130, 90 or more and less than 130, 1 or more and less than 125, 10 or more and less than 125, 50 or more and less than 125, 60 or more and less than 125, 70 or more and less than 125, 90 or more and less than 125, and the like. Examples include 5 or less, 1 to 120, 10 to 120, 50 to 120, 60 to 120, 70 to 120, 90 to 120, 1 to 110, 10 to 110, 50 to 110, 60 to 110, 70 to 110, 90 to 110, 1 to 100, 10 to 100, 50 to 100, 60 to 100, 70 to 100, and 90 to 100. When the spray particles are made of aluminum oxide, the calculated value of the left side of formula (1) is not particularly limited as long as it is less than 130, and examples of the calculated value include 125 or less, 1 or more, 10 or more, 50 or more, 60 or more, 70 or more, 90 or more, 100 or more, 110 or more, 120 or more, 1 or more and less than 130, 10 or more and less than 130, 50 or more and less than 130, 60 or more and less than 130, 70 or more and less than 130, 90 or more and less than 130, 100 or more and less than 130, 110 or more and less than 130, 120 or more and less than 130, 1 or more and less than 125, 10 or more and less than 125, 50 or more and less than 125, 60 or more and less than 125, 70 or more and less than 125, 90 or more and less than 125, 100 or more and less than 125, 110 or more and less than 125, and 120 or more and less than 125.When the spray particles are made of an oxide containing aluminum (Al) and yttrium (Y), the calculated value of the left side of formula (1) is not particularly limited as long as it is less than 130, but may be, for example, 125 or less, 120 or less, 110 or less, 100 or less, 1 or more, 10 or more, 50 or more, 60 or more, 70 or more, 90 or more, 100 or more, 110 or more, 120 or more, 1 or more and less than 130, 10 or more and less than 130, 50 or more and less than 130, 60 or more and less than 130, 70 or more and less than 130, 90 or more and less than 130, 100 or more and less than 130, 110 or more and less than 130, 120 or more and less than 130, 1 or more and less than 125, 10 or more and less than 125, 50 or more and less than 125, 60 or more and less than 125, 70 or more and less than 125, 90 or more and less than 125, 100 or more and less than 125, 110 or more and less than 125, 120 to 125, 1 to 125, 10 to 125, 50 to 125, 60 to 125, 70 to 125, 90 to 125, 100 to 125 , 110 to 125, 120 to 125, 1 to 120, 10 to 120, 50 to 120, 60 to 120, 70 to 120, 90 to 120 Examples include: 100 to 120, 110 to 120, 1 to 110, 10 to 110, 50 to 110, 60 to 110, 70 to 110, 90 to 110, 100 to 110, 1 to 100, 10 to 100, 50 to 100, 60 to 100, 70 to 100, and 90 to 100.

[0022] When judging whether or not the slurry for thermal spraying satisfies the relationship of formula (1), in the calculation of the left side of formula (1), prepare values ​​to one decimal place by rounding off to the first decimal place for E, α, and D90.

[0023] (Thermal spray particles) The aluminum-containing oxide constituting the spray particles made of an oxide containing aluminum is not particularly limited. The aluminum-containing oxide may be aluminum oxide (Al2O3), or may be an oxide containing an element other than aluminum (Al) and oxygen (O) in addition to aluminum (Al). The element other than aluminum (Al) and oxygen (O) is not particularly limited, and examples thereof include rare earth elements, silicon (Si), manganese (Mn), zirconium (Zr), titanium (Ti), chromium (Cr), molybdenum (Mo), platinum (Pt), iridium (Ir), zinc (Zn), calcium (Ca), sodium (Na), phosphorus (P), fluorine (F), and boron (B). Only one type of element other than aluminum (Al) and oxygen (O) may be contained, or two or more types may be contained. Examples of rare earth elements include scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), and lutetium (Lu). Only one rare earth element may be contained, or two or more rare earth elements may be contained. The oxide containing aluminum is preferably aluminum oxide, or an oxide containing aluminum (Al) and at least one selected from the group consisting of rare earth elements, silicon (Si), manganese (Mn), zirconium (Zr), titanium (Ti), chromium (Cr), molybdenum (Mo), platinum (Pt), iridium (Ir), zinc (Zn), calcium (Ca), sodium (Na), phosphorus (P), fluorine (F) and boron (B), more preferably aluminum oxide, or an oxide containing aluminum (Al) and a rare earth element, even more preferably aluminum oxide, or an oxide containing aluminum (Al) and yttrium (Y), even more preferably an oxide containing aluminum (Al) and yttrium (Y), and particularly preferably a composite oxide of aluminum (Al) and yttrium (Y).As the oxide containing aluminum (Al) and yttrium (Y), a composite oxide of aluminum (Al) and yttrium (Y) is particularly preferable. Specific examples of the composite oxide of aluminum (Al) and yttrium (Y) are not particularly limited, but include yttrium aluminum garnet (Y3Al5O. 12 ) (abbreviated as YAG), yttrium aluminum perovskite (YAlO3) (abbreviated as YAP), yttrium aluminum monoclinic (Y4Al2O9) (abbreviated as YAM), etc. As specific examples, the oxide containing aluminum is preferably aluminum oxide (Al2O3), YAG, YAP or YAM, more preferably YAG, YAP or YAM, and further preferably YAG.

[0024] The Young's modulus (E) of the aluminum-containing oxide at a temperature of 25° C. is not particularly limited. The Young's modulus (E) of the aluminum-containing oxide at a temperature of 25° C. is preferably 100.0 GPa or more, more preferably 150.0 GPa or more, and even more preferably 180.0 GPa or more. Within these ranges, cracks tend to occur more easily in the thermal spray coating, so the present invention can be used more effectively. The Young's modulus (E) of the aluminum-containing oxide at a temperature of 25° C. is preferably 500.0 GPa or less, more preferably 400.0 GPa or less, even more preferably 350.0 GPa or less, even more preferably 300.0 GPa or less, even more preferably 250.0 GPa or less, and particularly preferably 220.0 GPa or less. Within these ranges, cracks tend to occur less easily in the thermal spray coating. Preferred examples of the Young's modulus (E) of the aluminum-containing oxide at a temperature of 25° C. include 100.0 GPa or more and 500.0 GPa or less, 150.0 GPa or more and 400.0 GPa or less, 180.0 GPa or more and 350.0 GPa or less, 180.0 GPa or more and 300.0 GPa or less, 180.0 GPa or more and 250.0 GPa or less, and 180.0 GPa or more and 220.0 GPa or less.

[0025] The Young's modulus (E) of the aluminum-containing oxide at 25°C can be evaluated by the following method. Spray particles made of an oxide containing aluminum and an aqueous solution of an organic binder (Poval: 3-98, manufactured by Kuraray Co., Ltd.) are mixed in an amount of 2 parts by mass of the organic binder in terms of solid content per 100 parts by mass of the spray particles, and the resulting mixture is dried to obtain a powder. The obtained powder is uniaxially pressurized and molded at a pressure of 50 MPa to produce a molded body. The produced molded body is fired at 1,600°C for 12 hours at atmospheric pressure to obtain a bulk body. The obtained bulk body is cut to obtain a test piece (15 mm in diameter, 3 mm in thickness). The obtained test piece is measured at a temperature of 25°C by an ultrasonic pulse method using an ultrasonic thickness gauge (38DL PLUS, manufactured by Olympus Co., Ltd.) in accordance with JIS R1602:1995 "Test method for elastic modulus of fine ceramics".

[0026] The linear thermal expansion coefficient (α) of the oxide containing aluminum in the temperature range of 30°C to 600°C is not particularly limited. The linear thermal expansion coefficient (α) of the oxide containing aluminum in the temperature range of 30°C to 600°C is preferably 1.0 ppm / K or more, more preferably 5.0 ppm / K or more, even more preferably 6.9 ppm / K or more, and particularly preferably 8.0 ppm / K or more. In these ranges, cracks tend to occur more easily in the thermal spray coating, so the present invention can be used more effectively. The linear thermal expansion coefficient (α) of the oxide containing aluminum in the temperature range of 30°C to 600°C is preferably 20.0 ppm / K or less, more preferably 15.0 ppm / K or less, even more preferably 11.0 ppm / K or less, and particularly preferably 10.0 ppm / K or less. In these ranges, cracks tend to occur less easily in the thermal spray coating. Preferred examples of the linear thermal expansion coefficient (α) of an aluminum-containing oxide in the temperature range of 30°C to 600°C include 1.0 ppm / K or more and 20.0 ppm / K or less, 5.0 ppm / K or more and 15.0 ppm / K or less, 6.9 ppm / K or more and 15.0 ppm / K or less, 6.9 ppm / K or more and 11.0 ppm / K or less, 8.0 ppm / K or more and 11.0 ppm / K or less, and 8.0 ppm / K or more and 10.0 ppm / K or less.

[0027] The linear thermal expansion coefficient indicates the average linear expansion coefficient measured using a differential expansion thermomechanical analyzer in a specified temperature range. The linear thermal expansion coefficient in the temperature range from 30°C to 600°C is a value calculated by dividing the ratio of the change in the length of the test piece in the temperature range from 30°C to 600°C to the initial length of the test piece (30°C) (change in the length of the test piece in the temperature range from 30°C to 600°C / initial length of the test piece (30°C)) by the measured temperature difference. The linear thermal expansion coefficient (α) of an oxide containing aluminum in the temperature range from 30°C to 600°C can be evaluated by the following method. Spray particles made of an oxide containing aluminum and an aqueous solution of an organic binder (Poval: 3-98, manufactured by Kuraray Co., Ltd.) are mixed in an amount such that the organic binder is 2 parts by mass in terms of solid content per 100 parts by mass of the spray particles, and the resulting mixture is dried to obtain a powder. The obtained powder is uniaxially pressurized and molded at a pressure of 50 MPa to produce a molded body. The produced molded body is sintered at 1,600°C for 12 hours at atmospheric pressure to obtain a bulk body. The obtained bulk body is cut to obtain a test piece (5mm x 5mm x 10mm rectangular column shape). The test piece obtained above is measured in the measurement temperature range of 30°C to 600°C using a thermomechanical analyzer (TD5200SA, manufactured by NETZSCH Japan Co., Ltd.) in accordance with JIS R 1618:2002 "Method of measuring thermal expansion by thermomechanical analysis of fine ceramics", to obtain the linear thermal expansion coefficient (α) of the oxide containing aluminum in the temperature range of 30°C to 600°C.

[0028] The shape of the spray particles made of an oxide containing aluminum is not limited to a perfect sphere or a shape close to a sphere, and may be various shapes, such as an approximately spherical shape, a needle shape, a rod shape, a flake shape, a cube shape, or an amorphous shape.

[0029] In this specification, the volume-based cumulative 90% particle size (D90) refers to a particle size at which the cumulative frequency from the small particle size side is 90% in the volume-based cumulative particle size distribution based on the laser diffraction scattering type particle size distribution measurement method. The volume-based cumulative 90% particle size (D90) of the thermal spray particles made of an oxide containing aluminum is not particularly limited. The volume-based cumulative 90% particle size of the thermal spray particles made of an oxide containing aluminum is preferably 30.0 μm or less, more preferably 20.0 μm or less, even more preferably 17.0 μm or less, and particularly preferably 15.0 μm or less. Within these ranges, cracks tend to occur more easily in the thermal spray coating, so the present invention can be used more effectively. Furthermore, within these ranges, the surface roughness and / or porosity in the coating tend to be further reduced. The volume-based cumulative 90% particle size (D90) of the thermal spray particles made of an oxide containing aluminum is preferably more than 6.2 μm, more preferably more than 10.0 μm, and even more preferably 10.5 μm or more. Within these ranges, cracks tend to occur less easily in the thermal spray coating. Examples of preferred ranges for the volume-based cumulative 90% particle size (D90) of thermal spray particles made of an oxide containing aluminum include more than 6.2 μm and not more than 30.0 μm, more than 6.2 μm and not more than 20.0 μm, more than 10.0 μm and not more than 17.0 μm, and 10.5 μm or more and not more than 15.0 μm. When the thermal spray particles are made of aluminum oxide, the volume-based cumulative 90% particle size (D90) of the thermal spray particles is not particularly limited, but is particularly preferably more than 6.2 μm. Examples of preferred ranges for the volume-based cumulative 90% particle size (D90) of spray particles made of aluminum oxide include more than 6.2 μm and not more than 30.0 μm, more than 6.2 μm and not more than 20.0 μm, more than 10.0 μm and not more than 30.0 μm, more than 10.0 μm and not more than 20.0 μm, more than 10.5 μm and not more than 30.0 μm, and more than 10.5 μm and not more than 20.0 μm. When the spray particles are made of an oxide containing aluminum (Al) and yttrium (Y), the volume-based cumulative 90% particle size (D90) of the spray particles is not particularly limited, but is particularly preferably greater than 10.0 μm.Examples of preferred ranges for the volume-based cumulative 90% particle size (D90) of thermal spray particles made of an oxide containing aluminum (Al) and yttrium (Y) include more than 10.0 μm and not more than 30.0 μm, more than 10.0 μm and not more than 20.0 μm, more than 10.0 μm and not more than 17.0 μm, more than 10.0 μm and not more than 15.0 μm, 10.5 μm or more and not more than 30.0 μm, 10.5 μm or more and not more than 20.0 μm, 10.5 μm or more and not more than 17.0 μm, and 10.5 μm or more and not more than 15.0 μm.

[0030] In this specification, the volume-based cumulative 10% particle size (D10) refers to a particle size where the cumulative frequency from the small particle size side is 10% in the volume-based cumulative particle size distribution based on a laser diffraction scattering type particle size distribution measurement method, and the volume-based cumulative 50% particle size (D50) refers to a particle size where the cumulative frequency from the small particle size side is 50% in the volume-based cumulative particle size distribution based on a laser diffraction scattering type particle size distribution measurement method. The volume-based cumulative 10% particle size (D10) of the thermal spray particles made of an oxide containing aluminum is not particularly limited, but is preferably more than 1.8 μm and not more than 5.0 μm, more preferably more than 1.8 μm and not more than 4.0 μm, and even more preferably more than 1.9 μm and not more than 3.5 μm. The volume-based cumulative 50% particle size (D50) of the spray particles made of an oxide containing aluminum is not particularly limited, but is preferably more than 3.5 μm and not more than 9.0 μm, more preferably 4.5 μm or more and not more than 9.0 μm, and even more preferably more than 4.5 μm and not more than 9.0 μm.

[0031] The volume-based cumulative 10% particle diameter (D10) of thermal spray particles made of an oxide containing aluminum, the volume-based cumulative 50% particle diameter (D50) of thermal spray particles made of an oxide containing aluminum, and the volume-based cumulative 90% particle diameter (D90) of thermal spray particles made of an oxide containing aluminum can be measured by a laser diffraction scattering type particle size distribution measurement method. More specifically, a laser diffraction type particle size distribution measurement device is used to measure the volume-based particle size distribution in a thermal spray slurry containing thermal spray particles made of an oxide containing aluminum, and particle diameters at 10%, 50%, and 90% cumulative values ​​from the small particle size side in the obtained particle size distribution are obtained, and these particle diameters are defined as the volume-based cumulative 10% particle diameter (D10), the volume-based cumulative 50% particle diameter (D50), and the volume-based cumulative 90% particle diameter (D90), respectively.

[0032] The volume-based cumulative 10% particle size (D10) of the spray particles made of an oxide containing aluminum, the volume-based cumulative 50% particle size (D50) of the spray particles made of an oxide containing aluminum, and the volume-based cumulative 90% particle size (D90) of the spray particles made of an oxide containing aluminum can each be controlled, for example, by the particle pulverization conditions. For example, these particle sizes can be reduced by increasing the pressure of the high-pressure air introduced into the pulverization chamber. When two or more types of particles (powders) having different particle size distributions are mixed, these particle sizes can also be controlled by the mixing ratio of these. However, the method of controlling these particle sizes is not particularly limited.

[0033] The particles for thermal spraying may be commercially available products, particles obtained by processing commercially available products, or synthetic products.

[0034] The content of the spray particles in the slurry for thermal spraying according to this embodiment is not particularly limited. The content of the spray particles in the slurry for thermal spraying according to this embodiment is not particularly limited as long as it is more than 0 mass% with respect to the total mass of the slurry for thermal spraying, but is preferably 1 mass% or more, more preferably 2 mass% or more, even more preferably 3 mass% or more, and particularly preferably 4 mass% or more with respect to the total mass of the slurry for thermal spraying. Within these ranges, cracks tend to occur more easily in the thermal spray coating, so the present invention can be used more effectively. The content of the spray particles in the slurry for thermal spraying according to this embodiment is preferably less than 55 mass%, more preferably less than 51 mass%, even more preferably 50 mass% or less, even more preferably 49 mass% or less, even more preferably less than 31 mass%, even more preferably 30 mass% or less, even more preferably less than 11 mass%, and particularly preferably 10 mass% or less with respect to the total mass of the slurry for thermal spraying. Within these ranges, cracks tend to occur less easily in the thermal spray coating. Examples of preferred ranges for the content of the spray particles in the slurry for thermal spraying according to this embodiment include, relative to the total mass of the slurry for thermal spraying, more than 0 mass% and less than 55 mass%, more than 0 mass% and less than 51 mass%, more than 0 mass% and less than 50 mass%, more than 0 mass% and less than 49 mass%, at least 1 mass% and less than 31 mass%, at least 1 mass% and less than 30 mass%, at least 2 mass% and less than 11 mass%, at least 2 mass% and less than 10 mass%, at least 3 mass% and less than 11 mass%, at least 3 mass% and less than 10 mass%, and at least 4 mass% and less than 10 mass%.

[0035] (dispersion medium) The dispersion medium is not particularly limited. In the slurry for thermal spraying, the spray particles are dispersed in the dispersion medium. When the slurry for thermal spraying contains other components described below, the dispersion medium may disperse or dissolve the other components. Examples of the dispersion medium include water, an organic solvent, or a combination thereof. Examples of the organic solvent include, but are not particularly limited to, alcohols such as methanol, ethanol, and isopropyl alcohol, toluene, hexane, and kerosene. The dispersion medium preferably contains water. It is particularly preferable that the dispersion medium is water.

[0036] (Other ingredients) The slurry for thermal spraying according to this embodiment may further contain components other than the thermal spray particles made of an oxide containing aluminum and the dispersion medium (in this specification, the components other than the thermal spray particles made of an oxide containing aluminum and the dispersion medium are also referred to as "other components"). The other components are not particularly limited, and examples thereof include a pH adjuster, a dispersant, a viscosity adjuster, an antifoaming agent, an antiseptic, an antifungal agent, and a flocculant. Only one type of other component may be contained, or two or more types of other components may be contained.

[0037] The slurry for thermal spraying according to this embodiment preferably further contains a dispersant. The dispersant represents a component capable of improving the dispersion stability of the spray particles in the slurry for thermal spraying. The dispersant is not particularly limited. Examples of the dispersant include anionic dispersants, cationic dispersants, and nonionic dispersants. Specific examples of the anionic dispersants include polycarboxylic acid dispersants, naphthalene sulfonic acid dispersants, alkyl sulfonic acid dispersants, alkyl sulfonic acid dispersants, and polyphosphoric acid dispersants. Specific examples of the cationic dispersants include polyalkylene polyamine dispersants, quaternary ammonium dispersants, alkyl polyamine dispersants, and imidazoline dispersants. Specific examples of the nonionic dispersants include alkylene oxide dispersants and polyhydric alcohol ester dispersants. Examples of the polycarboxylic acid dispersants include sodium polycarboxylate (also known as sodium polycarboxylate) and ammonium polycarboxylate (also known as ammonium polycarboxylate). Examples of naphthalenesulfonic acid dispersants include sodium naphthalenesulfonate (also known as sodium naphthalenesulfonate) and ammonium naphthalenesulfonate (also known as ammonium naphthalenesulfonate). Examples of imidazoline dispersants include alkylimidazolines. The dispersant preferably contains at least one selected from the group consisting of anionic dispersants, cationic dispersants, and nonionic dispersants, more preferably contains an anionic dispersant, more preferably contains at least one selected from the group consisting of polycarboxylic acid dispersants, naphthalenesulfonic acid dispersants, alkylsulfonic acid dispersants, alkylsulfonic acid dispersants, and polyphosphoric acid dispersants, more preferably contains a polycarboxylic acid dispersant, more preferably contains at least one selected from the group consisting of sodium polycarboxylate and ammonium polycarboxylate, and particularly preferably contains ammonium polycarboxylate.

[0038] The dispersant may be contained in one type alone or in two or more types.

[0039] The content of the dispersant in the slurry for thermal spraying according to this embodiment is not particularly limited. The content of the dispersant in the slurry for thermal spraying according to this embodiment is preferably 0.001 parts by mass or more, more preferably 0.01 parts by mass or more, and even more preferably 0.02 parts by mass or more, in terms of solid content, relative to 100 parts by mass of the thermal spray particles. Within these ranges, the aggregation of the spray particles contained in the slurry can be further suppressed. The content of the dispersant in the slurry for thermal spraying according to this embodiment is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and even more preferably 1 part by mass or less, in terms of solid content, relative to 100 parts by mass of the thermal spray particles. Within these ranges, the occurrence of re-agglomeration can be further suppressed, and the maintenance of the dispersed state of the spray particles can be further improved. Preferred examples of the content of the dispersant in the slurry for thermal spraying according to this embodiment include 0.001 parts by mass or more and 10 parts by mass or less, 0.01 parts by mass or more and 5 parts by mass or less, and 0.02 parts by mass or more and 1 part by mass or less, in terms of solid content, relative to 100 parts by mass of the thermal spray particles. When two or more dispersants are used in combination, the content of the dispersant mentioned above refers to the total content of the two or more dispersants.

[0040] The total content of the spray particles, dispersant, and dispersion medium in the slurry for thermal spraying according to this embodiment is preferably more than 99 mass% (upper limit: 100 mass%) based on the total mass of the slurry for thermal spraying. The total content of the spray particles, dispersant, and dispersion medium in the slurry for thermal spraying according to this embodiment may be 100 mass% based on the total mass of the slurry for thermal spraying.

[0041] (solid content concentration) The solid content concentration of the slurry for thermal spraying according to this embodiment is not particularly limited. The solid content concentration of the slurry for thermal spraying according to this embodiment is preferably 1 mass% or more, more preferably 2 mass% or more, even more preferably 4 mass% or more, and particularly preferably 5 mass% or more. Within these ranges, cracks tend to occur more easily in the thermal spray coating, so the present invention can be used more effectively. The solid content concentration of the slurry for thermal spraying according to this embodiment is preferably 55 mass% or less, more preferably 51 mass% or less, even more preferably less than 50 mass%, even more preferably 31 mass% or less, even more preferably 30 mass% or less, even more preferably 11 mass% or less, and particularly preferably 10 mass% or less. Within these ranges, cracks tend to occur less easily in the thermal spray coating. Preferred examples of the solids concentration range of the slurry for thermal spraying according to this embodiment include 1 mass% or more and 55 mass% or less, 1 mass% or more and 51 mass% or less, 1 mass% or more and less than 50 mass%, 2 mass% or more and 31 mass% or less, 2 mass% or more and 30 mass% or less, 4 mass% or more and 11 mass% or less, 4 mass% or more and 10 mass% or less, and 5 mass% or more and 10 mass% or less.

[0042] The solids concentration of the slurry for thermal spraying can be calculated from the mass (total mass) of the slurry for thermal spraying and the mass of the solid residue obtained by drying the produced slurry for thermal spraying.

[0043] (Method for producing slurry for thermal spraying) The method for producing the slurry for thermal spraying according to this embodiment is not particularly limited. The slurry for thermal spraying can be produced by mixing a dispersion medium, thermal spray particles made of an oxide containing aluminum, and other components added as necessary. Mixing may be performed using a blade stirrer, a homogenizer, a mixer, or the like.

[0044] (base material) The slurry for thermal spraying is preferably used for the purpose of forming a thermal spray coating. When the slurry for thermal spraying is thermally sprayed toward a substrate, a thermal spray coating is formed on the substrate.

[0045] The material of the substrate is not particularly limited. Examples of the substrate include a metal substrate, an alloy substrate, and a ceramic substrate. Specific examples of the substrate material include aluminum, an aluminum alloy, iron, steel, copper, copper alloy, nickel, nickel alloy, gold, silver, bismuth, manganese, zinc, and zinc alloy. Among these, a substrate made of steel such as stainless steel, a substrate made of a heat-resistant alloy such as Inconel, a low-expansion alloy substrate such as Invar or Kovar, a corrosion-resistant alloy substrate such as Hastelloy, and a substrate made of aluminum or an aluminum alloy are preferred. By using these substrates, the effect of reducing cracks in the thermal spray coating tends to be enhanced. The reason for this is presumed to be as follows. The thermal expansion coefficient of these substrates is relatively large. Therefore, when these substrates expand due to the heat associated with thermal spraying and then contract after the end of thermal spraying, the contraction of these substrates is also relatively large. As a result, the thermal stress generated between the thermal spray coating and the substrate is easily reduced. Among these, a substrate made of a metal or an alloy is preferred, and a substrate made of aluminum or an aluminum alloy is particularly preferred. The substrate made of aluminum or an aluminum alloy is not particularly limited, but examples thereof include Al6061, Al6063, and the like.

[0046] (Thermal spraying method and method for producing thermal sprayed coating) The method of spraying the slurry for thermal spraying according to this embodiment may be high-velocity flame spraying, for example, high-velocity oxygen-fuel spraying (HVOF), in which the slurry for thermal spraying is supplied to the center of a high-velocity combustion flame jet flow generated by high-pressure oxygen (or air) and fuel and sprayed continuously at high speed, or plasma spraying, for example, atmospheric plasma spraying (APS) performed in the atmosphere, low pressure plasma spraying (LPS) performing spraying at a pressure lower than atmospheric pressure, or high pressure plasma spraying performing plasma spraying in a pressurized container at a pressure higher than atmospheric pressure. When the slurry for thermal spraying according to this embodiment is sprayed by high-velocity flame spraying or plasma spraying, the slurry for thermal spraying having a high content of ceramic particles can be sprayed with good fluidity, and a dense sprayed coating can be efficiently formed.

[0047] The spraying distance, i.e., the distance from the nozzle tip of the spraying device to the substrate, is not particularly limited. The spraying distance is preferably 60 mm or more. In this case, it is easy to suppress thermal alteration and thermal deformation of the substrate. The spraying distance is also preferably 200 mm or less. In this case, the spray particles are sufficiently heated during spraying, making it easy to obtain a dense sprayed coating. Therefore, a preferred example of the spraying distance is 60 mm or more and 200 mm or less.

[0048] The slurry for thermal spraying according to this embodiment is preferably used for high velocity flame thermal spraying or plasma thermal spraying, and more preferably used for plasma thermal spraying.

[0049] During thermal spraying, it is preferable to cool the outer periphery of the thermal spray jet from the surroundings by injecting water toward the periphery of the plasma jet, and it is particularly preferable to cool the outer periphery of the plasma jet by injecting water toward the periphery of the plasma jet during plasma spraying. Injection of water toward the periphery of the thermal spray jet is preferably performed using a water shroud device, and it is particularly preferable to spray water toward the periphery of the plasma jet using a water shroud device. The water shroud device is installed and used on the substrate side of the supply nozzle of the slurry for thermal spraying. In general, the water shroud is ring-shaped, and the thermal spray jet (e.g., plasma jet, etc.) and the supplied slurry for thermal spraying pass through its inside. Since a plurality of water injection ports are provided on the inner surface of the water shroud device, by supplying water from a water supply port different from the water injection port, cooling water is emitted from this water injection port toward the thermal spray jet (e.g., plasma jet, etc.). This prevents particles that are insufficiently melted on the outer periphery of the thermal spray jet (eg, plasma jet) from becoming unmelted and being incorporated into the coating, making it possible to improve the density of the coating.

[0050] The slurry for thermal spraying according to this embodiment is preferably used for thermal spraying performed while spraying water toward the periphery of the thermal spray jet. In this application, the slurry for thermal spraying is supplied to a thermal spray jet, and water is sprayed toward the periphery of the thermal spray jet to which the slurry for thermal spraying is supplied. The slurry for thermal spraying according to this embodiment is particularly preferably used for plasma spraying performed while spraying water toward the periphery of the plasma jet. In this application, the slurry for thermal spraying is supplied to a plasma jet, and water is sprayed toward the periphery of the plasma jet to which the slurry for thermal spraying is supplied. In these thermal sprayings, the slurry for thermal spraying and the particles that are not sufficiently molten at the outer periphery of the thermal spraying jet (particularly preferably, the plasma jet) are cooled and become in a non-molten state, and the deposition of the particles that are not sufficiently molten on the substrate is suppressed, and the sufficiently molten particles that mainly pass through the center of the thermal spraying jet (particularly preferably, the plasma jet) can be collided with the substrate surface. As a result, in such thermal spraying, the denseness of the coating can be improved.

[0051] From these points, it can be said that another aspect of the present invention relates to a method for producing a thermal spray coating, which includes spraying the slurry for thermal spraying according to the above aspect. The explanation of the thermal spraying method in this aspect is the same as the explanation of the method for spraying the slurry for thermal spraying according to the above aspect. The method for producing a thermal spray coating according to this aspect preferably includes spraying onto a metal substrate or an alloy substrate, and particularly preferably includes spraying onto a substrate made of aluminum or an aluminum alloy. The method for producing a thermal spray coating according to this aspect preferably includes supplying the slurry for thermal spraying according to the above aspect to a thermal spray jet, and spraying the slurry for thermal spraying while spraying water toward the periphery of the thermal spray jet. The method for producing a thermal spray coating according to this aspect particularly preferably includes supplying the slurry for thermal spraying according to the above aspect to a plasma jet, and plasma spraying the slurry for thermal spraying while spraying water toward the periphery of the plasma jet.

[0052] Although the embodiments of the present invention have been described in detail, it is apparent that the same are illustrative and exemplary, not restrictive, and the scope of the present invention should be interpreted by the appended claims.

[0053] The present invention encompasses the following aspects and configurations: [1] A slurry for thermal spraying comprising thermal spray particles made of an oxide containing aluminum and a dispersion medium, The slurry for thermal spraying has the following formula (1):

number

[0054] The present invention will be described in more detail with reference to the following examples and comparative examples, although the technical scope of the present invention is not limited to the following examples.

[0055] <Slurry for thermal spraying> (Production of Slurry for Thermal Spraying in Example 1) The spray particles were commercially available Y3Al5O 12 (YAG) particles (D50: 25 μm) were prepared and pulverized using a horizontal jet pulverizer to produce the slurry for thermal spraying of Example 1. The obtained spray particles, a dispersant containing ammonium polycarboxylate, and water as a dispersion medium were mixed so that the content of the spray particles was 10 mass% relative to the total mass of the slurry for thermal spraying, and the content of the dispersant was 0.05 mass parts in terms of solid content relative to 100 mass parts of the spray particles, thereby producing the slurry for thermal spraying of Example 1.

[0056] (Production of Slurry for Thermal Spraying in Example 2) A slurry for thermal spraying of Example 2 was produced in the same manner as the slurry for thermal spraying of Example 1, except that the grinding conditions were changed to produce thermal spray particles having the particle diameters shown in Table 1.

[0057] (Production of Slurry for Thermal Spraying in Examples 3 and 4 and Comparative Example 1) The slurries for thermal spraying of Examples 3 and 4 and Comparative Example 1 were each produced in the same manner as the production of the slurry for thermal spraying of Example 1, except that the crushing conditions were changed to produce the thermal spray particles with the particle diameters shown in Table 1, the content of the thermal spray particles was 30 mass% relative to the total mass of the slurry for thermal spraying, and the content of the dispersant was 0.05 parts by mass, calculated as solid content, relative to 100 parts by mass of the thermal spray particles.

[0058] (Production of Slurry for Thermal Spraying in Example 5 and Comparative Example 2) The slurries for thermal spraying of Example 5 and Comparative Example 2 were each produced in the same manner as in the production of the slurry for thermal spraying of Example 1, except that the crushing conditions were changed to produce the thermal spray particles with the particle diameters shown in Table 1, the content of the thermal spray particles was 50 mass% relative to the total mass of the slurry for thermal spraying, and the content of the dispersant was 0.05 parts by mass, calculated as solid content, relative to 100 parts by mass of the thermal spray particles.

[0059] (Production of Slurry for Thermal Spraying in Example 6) Commercially available Al2O3 particles A (D50: 3 ± 0.4 μm) and commercially available Al2O3 particles B (D50: 9.9 ± 0.8 μm) were prepared in a ratio (mass ratio) of A:B = 4:6. These two types of Al2O3 particles, a dispersant containing ammonium polycarboxylate, and water as a dispersion medium were mixed so that the total content of the two types of commercially available Al2O3 particles was 30 mass% with respect to the total mass of the slurry for thermal spraying, and the dispersant content was 0.05 mass parts in terms of solid content with respect to 100 mass parts of the total amount of the two types of commercially available Al2O3 particles, to produce a slurry for thermal spraying of Example 6. In this slurry for thermal spraying, the spray particles are Al2O3 particles obtained by mixing two types of commercially available Al2O3 particles in the above ratio (mass ratio).

[0060] (Production of Slurry for Thermal Spraying of Comparative Example 3) Commercially available Al2O3 particles (D50: 3±0.4 μm) were prepared as the spray particles. The spray particles, a dispersant containing ammonium polycarboxylate, and water as a dispersion medium were mixed so that the content of the spray particles was 30 mass% relative to the total mass of the slurry for thermal spraying, and the content of the dispersant was 0.05 mass parts in terms of solid content relative to 100 mass parts of the commercially available spray particles, to produce a slurry for thermal spraying of Comparative Example 3.

[0061] (Solid content of thermal spray slurry) The solid content concentration of the slurry for thermal spraying produced above was calculated from the mass (total mass) of the slurry for thermal spraying and the mass of the solid residue obtained by drying the slurry for thermal spraying at 105° C. The solid content concentrations of each slurry for thermal spraying are shown in Table 1. The solid content concentrations shown in Table 1 are values ​​calculated by rounding off to one decimal place.

[0062] (Young's modulus of oxides containing aluminum at 25℃) The Young's modulus (E) [unit: GPa] of the aluminum-containing oxide constituting the sprayed particles at a temperature of 25°C was evaluated as follows. The sprayed particles made of aluminum-containing oxide and an aqueous solution of an organic binder (Poval: 3-98, manufactured by Kuraray Co., Ltd.) were mixed in an amount of 2 parts by mass of the organic binder in terms of solid content per 100 parts by mass of the sprayed particles, and the resulting mixture was dried to obtain a powder. The obtained powder was uniaxially pressurized at a pressure of 50 MPa to produce a molded body. The produced molded body was fired at 1,600°C for 12 hours at atmospheric pressure to obtain a bulk body. The obtained bulk body was cut to obtain a test piece (15 mm in diameter, 3 mm in thickness). The obtained test piece was measured at a temperature of 25° C. using an ultrasonic thickness gauge (Olympus Corporation, 38DL PLUS) by an ultrasonic pulse method in accordance with JIS R1602:1995 "Testing method for elastic modulus of fine ceramics", and the obtained value was taken as the Young's modulus (E) of the aluminum-containing oxide at a temperature of 25° C. The obtained values ​​are shown in Table 1.

[0063] In this evaluation, the porosity of the test pieces of Examples 1 to 6 and Comparative Examples 1 to 3 measured by Archimedes' method was 3.9% by volume.

[0064] (Linear thermal expansion coefficient of oxides containing aluminum in the temperature range from 30℃ to 600℃) As described above, the linear thermal expansion coefficient [unit: ppm / K] in the temperature range from 30°C to 600°C is a value calculated by dividing the ratio of the change in the length of the test piece in the temperature range from 30°C to 600°C to the initial length of the test piece (30°C) (change in the length of the test piece in the temperature range from 30°C to 600°C / initial length of the test piece (30°C)) by the measured temperature difference. The linear thermal expansion coefficient (α) [unit: ppm / K] of the aluminum-containing oxide constituting the sprayed particles in the temperature range from 30°C to 600°C was evaluated as follows. The sprayed particles made of an aluminum-containing oxide and an aqueous solution of an organic binder (Poval: 3-98, manufactured by Kuraray Co., Ltd.) were mixed in an amount of 2 parts by mass of the organic binder in terms of solid content per 100 parts by mass of the sprayed particles, and the mixture obtained was dried to obtain a powder. The obtained powder was uniaxially pressurized and molded at a pressure of 50 MPa to produce a molded body. The produced molded body was sintered at 1,600°C for 12 hours at atmospheric pressure to obtain a bulk body. The obtained bulk body was cut to obtain a test piece (5mm x 5mm x 10mm rectangular column shape). The test piece obtained above was measured in the measurement temperature range of 30°C to 600°C using a thermomechanical analyzer (TD5200SA, manufactured by NETZSCH Japan Co., Ltd.) in accordance with JIS R 1618:2002 "Method of measuring thermal expansion by thermomechanical analysis of fine ceramics", to obtain the linear thermal expansion coefficient (α) [unit: ppm / K] of the oxide containing aluminum in the temperature range of 30°C to 600°C. The obtained values ​​are shown in Table 1.

[0065] In this evaluation, the porosity of the test pieces of Examples 1 to 6 and Comparative Examples 1 to 3 measured by Archimedes' method was 3.9% by volume.

[0066] (Particle diameter of thermal spray particles) As explained above, the volume-based cumulative 10% particle diameter (D10) refers to a particle diameter at which the cumulative frequency from the small particle diameter side is 10% in the volume-based cumulative particle diameter distribution based on the laser diffraction scattering particle size distribution measurement method, the volume-based cumulative 50% particle diameter (D50) refers to a particle diameter at which the cumulative frequency from the small particle diameter side is 50% in the volume-based cumulative particle diameter distribution based on the laser diffraction scattering particle size distribution measurement method, and the volume-based cumulative 90% particle diameter (D90) refers to a particle diameter at which the cumulative frequency from the small particle diameter side is 90% in the volume-based cumulative particle diameter distribution based on the laser diffraction scattering particle size distribution measurement method.

[0067] A laser diffraction particle size distribution measuring device (Malvern Panalytical, Mastersizer 3000) was used to measure the volumetric particle size distribution in the thermal spray slurry, and particle sizes at 10%, 50%, and 90% cumulative values ​​from the small particle size side in the particle size distribution were obtained. These particle sizes were designated as the volumetric cumulative 10% particle size (D10) [unit: μm] of the thermal spray particles, the volumetric cumulative 50% particle size (D50) [unit: μm] of the thermal spray particles, and the volumetric cumulative 90% particle size (D90) [unit: μm] of the thermal spray particles, respectively. The obtained values ​​are shown in Table 1.

[0068] (Confirmation of the relationship in formula (1)) For the slurry for thermal spraying produced above, the value of the left side of equation (1) was calculated using the values ​​obtained from the respective measurements, and it was confirmed whether the slurry for thermal spraying produced above satisfied the relationship of equation (1).

[0069]

number

[0070] E: Young's modulus of the aluminum-containing oxide that constitutes the thermal spray particles at a temperature of 25°C [unit: GPa], α: Linear thermal expansion coefficient of the aluminum-containing oxide that constitutes the thermal spray particles in the temperature range from 30°C to 600°C [unit: ppm / K], D90: Cumulative 90% particle size by volume of spray particles [unit: μm].

[0071] Here, in determining whether the slurry for thermal spraying produced above satisfies the relationship of formula (1), values ​​were prepared and used for E, α, and D90 in the calculation of the left side of formula (1) by rounding off to one decimal place. Note that Table 1 lists the values ​​of E, α, and D90 prepared in this way to one decimal place.

[0072] The calculated values ​​of the left side of formula (1) are shown in Table 1. Note that in Table 1, the calculation results of the left side of formula (1) are rounded off to the nearest tenths place.

[0073] <Thermal spray coating> (Manufacturing of thermal spray coatings) Using a plasma spraying device 100HE manufactured by Progressive Surface, the slurry for thermal spraying produced above was sprayed onto a substrate made of an aluminum alloy (hereinafter also simply referred to as "aluminum alloy substrate") to produce a thermal spray coating on the aluminum alloy substrate. A supply device for supplying the slurry for thermal spraying to the plasma spraying device was a LiquifeederHE (trade name) SPS / SPPS feed system manufactured by Progressive Surface. The plasma spraying device was used in combination with a water shroud device, and the water shroud device was a LiquiEdge (trademark) Thermal Spray Shroud manufactured by Progressive Surface. The water shroud device was installed on the substrate side of the supply nozzle for the slurry for thermal spraying. Thermal spraying was performed while injecting cooling water from the water injection port of the water shroud device toward the periphery of the plasma jet. The thermal spraying conditions were as follows. The obtained thermal spray coating had a thickness of 50 μm.

[0074] <Thermal spraying conditions> Argon gas flow rate: 135NL / min Nitrogen gas flow rate: 52.5NL / min Hydrogen gas flow rate: 52.5NL / min Plasma power: 105kW Spraying distance: 86 mm (Examples 1-5, Comparative Examples 1-2), 76 mm (Example 6, Comparative Example 3) Traverse speed: 1500mm / s Spray angle: 90° Slurry supply amount: 38mL / min Substrate: Aluminum alloy substrate (Al6061, 50mm x 50mm x 5mm).

[0075] (Cracks in thermal spray coating) The surface of the thermal spray coating produced above was observed using a digital microscope (VHX-5000) manufactured by Keyence Corporation at a lens magnification of 30 times to check for the presence or absence of cracks. The evaluation results are shown in Table 1. In Table 1, cases where cracks were confirmed in the thermal spray coating were recorded as "B," and cases where no cracks were confirmed in the thermal spray coating were recorded as "A."

[0076] Note that a digital microscope image of the surface of the thermal sprayed coating formed using the thermal spraying slurry of Example 1 is shown in FIG. 1, a digital microscope image of the surface of the thermal sprayed coating formed using the thermal spraying slurry of Comparative Example 1 is shown in FIG. 2, and a digital microscope image of the surface of the thermal sprayed coating formed using the thermal spraying slurry of Comparative Example 2 is shown in FIG. 3.

[0077] From the results in Table 1, it was confirmed that the thermal spray coating produced using the thermal spray slurry containing the thermal spray particles made of an oxide containing aluminum and a dispersion medium according to the embodiment and satisfying formula (1) had significantly reduced cracking. On the other hand, it was confirmed that the thermal spray coating produced using the comparative example slurry not satisfying formula (1) was prone to cracking.

[0078] [Table 1]

Claims

1. A slurry for thermal spraying comprising thermal spray particles made of an oxide containing aluminum and a dispersion medium, The slurry for thermal spraying has the following formula (1): [0010] Fulfilling In the above formula (1), E is the Young's modulus of the oxide at a temperature of 25° C. [unit: GPa], α is the linear thermal expansion coefficient (unit: ppm / K) of the oxide in the temperature range from 30° C. to 600° C., D90 is the volume-based cumulative 90% particle diameter of the spray particles [unit: μm]; Slurry for thermal spraying.

2. The slurry for thermal spraying according to claim 1 , wherein the slurry for thermal spraying has a solids concentration of 55 mass % or less.

3. The thermal spray slurry of claim 1 further comprising a dispersant.

4. The thermal spray slurry according to claim 1 , wherein the oxide is an oxide containing aluminum and yttrium.

5. 2. The slurry for thermal spraying according to claim 1, which is used in thermal spraying performed while spraying water toward the periphery of a thermal spray jet.

6. A method for producing a thermal spray coating, comprising thermal spraying the slurry for thermal spraying according to any one of claims 1 to 5.

Images