Powder for thermal spraying

Abstract

PROBLEM TO BE SOLVED: To provide a powder for thermal spraying which has a large size and can form splats having a uniform size. SOLUTION: A powder for thermal spraying which has a volume-based cumulative 50% particle diameter (D50) of 35.0 μm or greater and a powder cross-sectional porosity of 30.0% or less.

Description

Thermal spray powder

[0001] This invention relates to a powder for thermal spraying.

[0002] Conventionally, plasma spraying and explosive spraying have been widely used as methods for forming dense thermal spray coatings on surfaces of ceramics, metals, and other materials. In these thermal spraying methods, metals and metal oxides are used as spray particles. In recent years, in plasma processes for semiconductor manufacturing, rare earth element-containing compounds are being developed as wafer processing materials in halogen-based corrosive gases due to their high plasma resistance. For example, Patent Document 1 discloses spherical spray particles formed from a compound containing rare earth elements (including yttrium).

[0003] The document sets forth the objectives of "providing spherical particles for thermal spraying that have sufficient fracture strength and do not collapse even in the flame (plasma) during thermal spraying" and "providing highly pure spherical particles for thermal spraying that can form a smooth and dense thermal spray coating even when using a high-melting-point rare earth element-containing compound, and that do not generate particles," and then describes spherical particles for thermal spraying (Claim 1) formed from a rare earth element (including yttrium)-containing compound, characterized by a fracture strength of 10 MPa or more and an average particle size of 10 to 80 μm, and a rare earth element (including yttrium)-containing compound with a bulk density of 1.0 g / cm³. ３ In summary, if the aspect ratio is 2 or less and the pore radius is 1 μm or less, the cumulative pore volume is 0.5 cm³. ３ We attempt to solve the above problem by providing two embodiments of spherical particles for thermal spraying: one characterized by being spherical in shape with a weight of less than 1g (Claim 2), and the other characterized by being spherical in shape.

[0004] Japanese Patent Publication No. 2002-363724

[0005] The problem that this invention aims to solve is to provide a thermal spray powder capable of forming large, uniformly sized splatters.

[0006] The inventors diligently studied to solve the above problems. As a result, they conceived the idea of ​​controlling the proportion of voids between multiple primary particles constituting the thermal spray powder within the cross-section of the thermal spray powder. They defined this as the powder cross-sectional void ratio, and found that the above problems could be solved by using thermal spray powder in which this powder cross-sectional void ratio is below a certain value and the volume-based cumulative 50% particle size (D50) is greater than or equal to a certain size, thus completing the present invention.

[0007] Therefore, one aspect of the present invention is a thermal spray powder having a volume-based cumulative 50% particle size (D50) of 35.0 μm or more and a powder cross-sectional porosity of 30.0% or less.

[0008] According to the present invention, it is possible to provide a thermal spray powder capable of forming large, uniformly sized splatters.

[0009] Figure 1 is a micrograph of the splat test specimen from Example 2 at a magnification of 200x. Figure 2 is a micrograph of the splat test specimen from Comparative Example 3 at a magnification of 200x.

[0010] In this specification, "X to Y" is used to mean "X or greater and Y or less," including the numerical values ​​(X and Y) before and after it as the lower and upper limits. When multiple instances of "X to Y" or "X or greater and Y or less" are listed, for example, "X1 to Y1, or X2 to Y2," the disclosure of each numerical value as the upper limit, the disclosure of each numerical value as the lower limit, and all combinations of these upper and lower limits are disclosed (i.e., they provide a lawful basis for correction). Specifically, corrections to X1 or greater, corrections to Y2 or less, corrections to X1 or less, corrections to Y2 or greater, corrections to X1 to X2, corrections to X1 to Y2, etc., must all be considered lawful. Note that the description "X or greater" means X or greater than X, and therefore includes the meaning of "greater than X." Similarly, the description "Y or less" means Y or less than Y, and therefore includes the meaning of "less than Y." Furthermore, unless otherwise specified, operations and measurements of physical properties, etc., shall be performed under room temperature (20-25°C) / relative humidity of 40-50% RH. It should also be understood that all embodiments and combinations of descriptions disclosed herein are disclosed in this application; that is, they may serve as grounds for amendments. Additionally, when descriptions of the content or concentration of each component are given, if two or more are included, the total amount may be given.

[0011] <Thermal Spray Powder> One aspect of the present invention is a thermal spray powder having a volume-based cumulative 50% particle diameter (D50) of 35.0 μm or more and a powder cross-sectional porosity of 30.0% or less. Patent Document 1 mentioned above does not disclose a thermal spray powder that forms large, uniformly sized splatters. The present inventors have found that by providing a thermal spray powder having a volume-based cumulative 50% particle diameter (D50) of 35.0 μm or more and a powder cross-sectional porosity of 30.0% or less, it is possible to form large, uniformly sized splatters.

[0012] According to one embodiment of the present invention, the thermal spraying powder may comprise thermal spray particles made of ceramics. Examples of the ceramics include oxide-based ceramics formed of oxides of various metals, carbide-based ceramics formed of carbides of various metals, nitride-based ceramics formed of nitrides of various metals, or non-oxide-based ceramics formed of non-oxides such as borides, fluorides, hydroxides, carbonates and phosphates of various metals. Oxide-based ceramics are preferable for protecting the semiconductor device itself from plasma etching in the etching step of semiconductor manufacturing.

[0013] Examples of the metal elements constituting the various metals include metalloid elements such as B, Si, Ge, Sb and Bi; typical metal elements such as Na, Mg, Ca, Sr, Ba, Zn, Al, Ga, In, Sn, Pb and P; transition metal elements such as La, Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Mn, Fe, Co, Ni, Cu, Ag and Au; lanthanide group rare earth elements such as La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu; scandium group rare earth elements such as Sc and Y; and one or more selected from the foregoing. Among them, for protecting the semiconductor device itself from plasma etching in the etching step of semiconductor manufacturing, the thermal spraying powder preferably contains a rare earth element, more preferably contains a scandium group rare earth element, and still more preferably contains yttrium (Y) element.

[0014] According to one embodiment of the present invention, examples of the oxide-based ceramics include alumina (Al ２ O ３ ), zirconia (ZrO ２ ), yttria (Y ２ O ３ ), chromia (Cr ２ O ３ ), titania (TiO ２ ), magnesia (MgO), silica (SiO ２ ), calcia (CaO), ceria (CeO ２Examples of elemental oxides include yttria (Y) and others. In particular, to protect the semiconductor device itself from plasma etching in the etching process of semiconductor manufacturing, yttria (Y) is used. ２ O ３ ) is preferable. Yttria (Y ２ O ３ ) usually forms a white thermal spray coating. And yttria (Y ２ O ３ Yttria is a preferred material for forming thermal spray coatings that have erosion resistance to plasma. For example, excellent corrosion resistance can be obtained by forming a yttria coating on the anodized surface of a high-purity aluminum alloy processing chamber or the surface of a processed part.

[0015] According to one embodiment of the present invention, the oxide ceramic may be a composite oxide. For example, the thermal spray powder may be yttria (Y ２ O ３ ) and alumina (Al ２ O ３ The composite oxide consists of (Y) and alumina. The composite oxide consisting of yttria and alumina has excellent corrosion resistance and oxidation resistance, making it suitable as a coating material for components made of materials inferior in these respects. The composite oxide consisting of yttria and alumina can also be made into yttrium-aluminum complex oxide powder, or a mixture of yttria powder and alumina powder, such as yttrium aluminum garnet (abbreviated as YAG), yttrium aluminum perovskite (abbreviated as YAP), or yttrium aluminum monoclinic (abbreviated as YAM), by appropriately adjusting the mixing ratio of yttria and alumina. Note that YAG, YAM, and YAP are each (Y) ２ O ３ :57.1% by mass, Al ２ O ３ :42.9% by mass), (Y ２ O ３ :81.6% by mass, Al ２ O ３ : 18.4% by mass, and YAP (Y ２ O ３ :68.9% by mass, Al ２ O３ It can be produced by mixing and firing in a ratio of 31.1% by mass.

[0016] According to one embodiment of the present invention, a rare earth silicate is an example of a composite oxide. The rare earth silicate is RE ２ Si ２ O ７ or RE ２ SiO ５ The compound may also be represented as (RE is a rare earth element). For example, Y ２ SiO ５ , Y ２ Si ２ O ７ Yb ２ Si ２ O ７ Yb ２ SiO ５ ErSi ２ O ７ Er ２ SiO ５ Ho ２ Si ２ O ７ Ho ２ SiO ５ , Dy ２ Si ２ O ７ , Dy ２ SiO ５ , Gd ２ SiO ５ , Gd ２ Si ２ O ７ These are some examples. Using such rare-earth silicates has the effect of expanding the range of semiconductor products to which they can be applied.

[0017] [Particle Size] (Particle Size (D50) of Thermal Spray Powder) The volume-based cumulative 50% particle size (D50) of the thermal spray powder disclosed herein is 35.0 μm or larger. Because the 50% particle size (D50) of the thermal spray powder is significantly larger, the size of the splatters of the coating formed using it is also significantly larger, improving corrosion resistance. Therefore, even if the coating is exposed to plasma in the etching process of semiconductor manufacturing, corrosion of the coating is suppressed, and thus the generation of particles due to coating corrosion can be suppressed. In one embodiment of the present invention, the volume-based cumulative 50% particle size (D50) of the thermal spray powder is 36.0 μm or more, 37.0 μm or more, 38.0 μm or more, 39.0 μm or more, 40.0 μm or more, 41.0 μm or more, 42.0 μm or more, 43.0 μm or more, 44.0 μm or more, 45.0 μm or more, 46.0 μm or more, greater than 46.6 μm, 47.0 μm or more, 48.0 μm or more, 49.0 μm or more, 50.0 μm or more, 51.0 μm or more, 52.0 μm or more, 53.0 μm or more, or 54.0 μm or more. When the 50% particle size (D50) of the thermal spray powder is appropriately large, it has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed.

[0018] In one embodiment of the present invention, the volume-based cumulative 50% particle size (D50) of the thermal spray powder is 67.0 μm or less, 66.0 μm or less, 65.0 μm or less, 64.0 μm or less, 63.0 μm or less, 62.0 μm or less, 61.0 μm or less, 60.0 μm or less, 59.0 μm or less, 58.0 μm or less, 57.0 μm or less, 56.0 μm or less, 55 . 0 μm or less, 54.0 μm or less, 53.0 μm or less, 52.0 μm or less, 51.0 μm or less, 50.0 μm or less, 49.0 μm or less, 48.0 μm or less, 47.0 μm or less, less than 46.8 μm, 46.0 μm or less, 45.0 μm or less, 44.0 μm or less, 43.0 μm or less, 42.0 μm or less, or 41.0 μm or less. When the volume-based cumulative 50% particle size (D50) of the thermal spray powder is appropriately small, it has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed. In one embodiment of the present invention, the volume-based cumulative 50% particle size (D50) of the thermal spray powder is 35.0 μm or more and 67.0 μm or less.

[0019] Here, the volume-based cumulative 50% particle size (D50) of the thermal spray powder means the particle size (D50) at which the cumulative particle volume from the small particle size side accounts for 50% of the total particle volume in the volume-based cumulative particle size distribution of the thermal spray powder using the laser diffraction scattering particle size distribution measurement method (also referred to simply as "D50" or "particle size (D50)" in this specification).

[0020] Similarly, the volume-based cumulative 5% particle diameter (D5), volume-based cumulative 10% particle diameter (D10), volume-based cumulative 90% particle diameter (D90), and volume-based cumulative 95% particle diameter (D95) of thermal spray powder, as described later, refer to the particle diameters at 5%, 10%, 90%, and 95% of the total particle volume in the volume-based cumulative particle diameter distribution, respectively. These are also simply referred to as "D5" or "particle diameter (D5)", "D10" or "particle diameter (D10)", "D90" or "particle diameter (D90)", and "D95" or "particle diameter (D95)", respectively.

[0021] (Particle size (D5) of thermal spray powder) In one embodiment of the present invention, the particle size (D5) of the thermal spray powder is 17.0 μm or more, 19.0 μm or more, 21.0 μm or more, 23.0 μm or more, 25.0 μm or more, 27.0 μm or more, 29.0 μm or more, 31.0 μm or more, greater than 31.9 μm, 33.0 μm or more, 35.0 μm or more, 37.0 μm or more, or 39.0 μm or more. Since the particle size (D5) of the thermal spray powder is significantly large, the size of the splatters of the coating formed using it is also significantly larger, improving corrosion resistance. Therefore, the generation of particles due to coating corrosion can be suppressed. In addition, when the (D5) of the thermal spray powder is appropriately large, it has the effect of reducing the porosity of the powder cross-section. Therefore, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed.

[0022] In one embodiment of the present invention, the particle size (D5) of the thermal spray powder is 45.0 μm or less, 43.0 μm or less, 41.0 μm or less, 39.0 μm or less, 37.0 μm or less, 35.0 μm or less, 33.0 μm or less, less than 32.9 μm, or 31.0 μm or less. When the particle size (D5) of the thermal spray powder is appropriately small, it has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed. In one embodiment of the present invention, the particle size (D5) of the thermal spray powder is 17.0 μm or more and 45.0 μm or less.

[0023] (Particle size (D10) of thermal spray powder) In one embodiment of the present invention, the particle size (D10) of the thermal spray powder is 21.0 μm or more, 23.0 μm or more, 25.0 μm or more, 27.0 μm or more, 29.0 μm or more, 31.0 μm or more, 33.0 μm or more, 35.0 μm or more, greater than 34.6 μm, 37.0 μm or more, 39.0 μm or more, 41.0 μm or more, or 43.0 μm or more. If the particle size (D10) of the thermal spray powder is significantly large, the size of the splatters of the coating formed using it will also be significantly larger, improving corrosion resistance. Therefore, the generation of particles due to coating corrosion can be suppressed. In addition, if the particle size (D10) of the thermal spray powder is moderately large, it has the effect of reducing the porosity of the powder cross-section. Therefore, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed.

[0024] In one embodiment of the present invention, the particle size (D10) of the thermal spray powder is 54.0 μm or less, 52.0 μm or less, 50.0 μm or less, 48.0 μm or less, 46.0 μm or less, 44.0 μm or less, 42.0 μm or less, 40.0 μm or less, 38.0 μm or less, 36.0 μm or less, less than 35.7 μm, 34.0 μm or less, or 32.0 μm or less. When the (D10) of the thermal spray powder is appropriately small, it has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed. In one embodiment of the present invention, the particle size (D10) of the thermal spray powder is 21.0 μm or more and 54.0 μm or less.

[0025] (Particle size (D90) of thermal spray powder) In one embodiment of the present invention, the particle size (D90) of the thermal spray powder is 42.0 μm or more, 44.0 μm or more, greater than 45.0 μm, 46.0 μm or more, 48.0 μm or more, 50.0 μm or more, 52.0 μm or more, 54.0 μm or more, 56.0 μm or more, 58.0 μm or more, 60.0 μm or more, greater than 60.6 μm, 62.0 μm or more, 64.0 μm or more, 66.0 μm or more, or 68.0 μm or more. When the particle size (D90) of the thermal spray powder is significantly large, the size of the splatters of the coating formed using it is also significantly larger, improving corrosion resistance. Therefore, the generation of particles due to coating corrosion can be suppressed. In addition, when the particle size (D90) of the thermal spray powder is moderately large, it has the effect of reducing the porosity of the powder cross-section. Therefore, a dense coating can be formed, which in turn can suppress the generation of particles due to coating corrosion.

[0026] In one embodiment of the present invention, the particle size (D90) of the thermal spray powder is 69.0 μm or less, 67.0 μm or less, 65.0 μm or less, 63.0 μm or less, less than 61.5 μm, 61.0 μm or less, 59.0 μm or less, 57.0 μm or less, 55.0 μm or less, or 53.0 μm or less. When the particle size (D90) of the thermal spray powder is appropriately small, it has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed. In one embodiment of the present invention, the particle size (D90) of the thermal spray powder is 42.0 μm or more and 69.0 μm or less.

[0027] (Particle size (D95) of thermal spray powder) In one embodiment of the present invention, the particle size (D95) of the thermal spray powder is 50.0 μm or more, 52.0 μm or more, 54.0 μm or more, 56.0 μm or more, 58.0 μm or more, 60.0 μm or more, 62.0 μm or more, 64.0 μm or more, greater than 65.0 μm, 66.0 μm or more, 68.0 μm or more, or 70.0 μm or more. If the particle size (D95) of the thermal spray powder is significantly large, the size of the splatters of the coating formed using it will also be significantly larger, improving corrosion resistance. Therefore, the generation of particles due to coating corrosion can be suppressed. In addition, if the particle size (D95) of the thermal spray powder is moderately large, it has the effect of reducing the porosity of the powder cross-section. Therefore, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed.

[0028] In one embodiment of the present invention, the particle size (D95) of the thermal spray powder is 75.0 μm or less, 73.0 μm or less, 71.0 μm or less, 69.0 μm or less, 67.0 μm or less, less than 65.8 μm, 65.0 μm or less, 63.0 μm or less, 61.0 μm or less, 59.0 μm or less, or 57.0 μm or less. In one embodiment of the present invention, the particle size (D95) of the thermal spray powder is 50.0 μm or more and 75.0 μm or less. When the particle size (D95) of the thermal spray powder is appropriately small, it has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed. In one embodiment of the present invention, the particle size (D90) of the thermal spray powder is 50.0 μm or more and 75.0 μm or less.

[0029] (Content of particles with a particle size of 75 μm or larger) In one embodiment of the present invention, the content of particles with a particle size of 75 μm or larger in the thermal spray powder is 0.50% by mass or less. As a method for measuring the content of particles with a particle size of 75 μm or larger in the thermal spray powder, for example, it can be determined using a rotap tester (see JIS R6002:1998). By producing a coating using thermal spray powder in which the content of particles with a particle size of 75 μm or larger is 0.50% by mass or less, there is an effect of suppressing discoloration of the resulting coating. This effect is obtained on the premise that the coating is produced using thermal spray powder in which the volume-based cumulative 50% particle size (D50) is 35.0 μm or more and the powder cross-sectional porosity is 30.0% or less. The inventors have confirmed that even if the coating is produced using thermal spray powder in which the volume-based cumulative 50% particle size (D50) is less than 35.0 μm or the powder cross-sectional porosity is greater than 30%, the phenomenon of discoloration is not observed. Therefore, providing a thermal spray powder having a volume-based cumulative 50% particle diameter (D50) of 35.0 μm or more and a powder cross-sectional porosity of 30.0% or less, in which the content of particles with a particle diameter of 75 μm or more is 0.50 mass% or less, can be said to solve a previously unknown problem. In one embodiment of the present invention, the content of particles with a particle diameter of 75 μm or more in the thermal spray powder is 0.40 mass% or less, 0.30 mass% or less, 0.20 mass% or less, 0.10 mass% or less, 0.08 mass% or less, 0.06 mass% or less, 0.04 mass% or less, 0.02 mass% or less, less than 0.02 mass%, or 0 mass%.

[0030] (Content of particles with a particle diameter of 63 μm or more) In one embodiment of the present invention, the content of particles with a particle diameter of 63 μm or more in the thermal spray powder is greater than 0 mass%, 0.01 mass% or more, 0.05 mass% or more, 0.09 mass% or more, greater than 0.12 mass%, 0.15 mass% or more, 0.20 mass% or more, 0.25 mass% or more, 0.30 mass% or more, 0.35 mass% or more, 0.40 mass% or more, 1.00 mass% or more, 2.00 mass% or more, 3.00 mass% or more, 4.00 mass% or more, 5.00 mass% or more, 6.00 mass% or more, or 7.00 mass% or more. The content of particles with a particle diameter of 63 μm or more in the thermal spray powder can be determined, for example, using a rotap tester (see JIS R6002:1998). In one embodiment of the present invention, the content of particles with a particle size of 63 μm or larger in the thermal spray powder is 10.00% by mass or less, 9.00% by mass or less, 8.00% by mass or less, 7.00% by mass or less, 6.00% by mass or less, 5.00% by mass or less, 4.00% by mass or less, 3.00% by mass or less, 2.00% by mass or less, 1.00% by mass or less, 0.90% by mass or less, 0.70% by mass or less, 0.50% by mass or less, less than 0.48% by mass, 0.40% by mass or less, 0.35% by mass or less, 0.30% by mass or less, 0.10% by mass or less, 0.08% by mass or less, 0.05% by mass or less, 0.04% by mass or less, or 0.03% by mass or less. By appropriately adjusting the content of particles with a particle size of 63 μm or larger in the thermal spray powder, the span value of the thermal spray powder can be set to a suitable value, and consequently, large and uniformly sized splatters can be stably formed.

[0031] (Content of particles with a particle diameter of 53 μm or more) In one embodiment of the present invention, the content of particles with a particle diameter of 53 μm or more in the thermal spray powder is 5.00% by mass or more, 7.00% by mass or more, 9.00% by mass or more, 11.00% by mass or more, 13.00% by mass or more, more than 13.57% by mass, 15.00% by mass or more, 17.00% by mass or more, 19.00% by mass or more, 21.00% by mass or more, 23.00% by mass or more, 25.00% by mass or more, 27.00% by mass or more, 29.00% by mass or more, 31.00% by mass or more, 33.00% by mass or more, or 35.00% by mass or more. The content of particles with a particle diameter of 53 μm or more in the thermal spray powder can be determined, for example, using a rotap tester (see JIS R6002:1998). In one embodiment of the present invention, the content of particles with a particle size of 53 μm or larger in the thermal spray powder is 40.00% by mass or less, 37.00% by mass or less, 34.00% by mass or less, 31.00% by mass or less, 29.00% by mass or less, 27.00% by mass or less, 25.00% by mass or less, 23.00% by mass or less, 21.00% by mass or less, less than 20.44% by mass, 20.00% by mass or less, 19.00% by mass or less, 17.00% by mass or less, 15.00% by mass or less, 13.00% by mass or less, or 11.00% by mass or less. By appropriately adjusting the content of particles with a particle size of 53 μm or larger in the thermal spray powder, the span value of the thermal spray powder can be set to a suitable value, and consequently, splatters with a large size and uniform size can be stably formed.

[0032] (Span Value) In one embodiment of the present invention, the span value of the thermal spray powder is less than 1.0. The span value is a value calculated by the formula {particle diameter (D90) μm - particle diameter (D10) μm} / particle diameter (D50) μm. As described above, the 50% particle diameter (D50) of the thermal spray powder disclosed herein is significantly large, so the size of the splats of the coating formed using it is also significantly larger, improving corrosion resistance. Furthermore, by making the span value of the thermal spray powder significantly smaller, to less than 1.0, the size of the splats of the coating obtained using the thermal spray powder becomes uniform. Thus, even if the coating is exposed to plasma in the etching process of semiconductor manufacturing, the size of the splats of the coating is significantly larger and more uniform, so the coating becomes denser, and corrosion of the coating is further suppressed. Therefore, the generation of particles due to coating corrosion can be suppressed.

[0033] In one embodiment of the present invention, the span value of the thermal spray powder is 0.9 or less, 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, or 0.4 or less. By having an appropriately small span value of the thermal spray powder, the generation of particles due to coating corrosion can be further suppressed. Also, by having an appropriately small span value of the thermal spray powder, the value of the powder cross-sectional porosity of the thermal spray powder can be reduced, and consequently, the generation of particles due to coating corrosion can be further suppressed. In one embodiment of the present invention, the span value of the thermal spray powder is 0.3 or more, 0.4 or more, 0.5 or more, or 0.6 or more. By appropriately adjusting the lower limit of the span value of the thermal spray powder, the value of the powder cross-sectional porosity of the thermal spray powder can be reduced, and consequently, the generation of particles due to coating corrosion can be further suppressed.

[0034] (Dispersion Index) In one embodiment of the present invention, the dispersion index of the thermal spray powder is less than 0.481. The dispersion index is a value calculated by the formula {particle size (D90) μm - particle size (D10) μm} / {particle size (D90) μm + particle size (D10) μm}. By making the dispersion index of the thermal spray powder significantly smaller, to less than 0.481, the size of the resulting splats is also uniform. Therefore, even if the coating is exposed to plasma in the etching process of semiconductor manufacturing, the generation of particles due to coating corrosion can be further suppressed.

[0035] In one embodiment of the present invention, the dispersion index of the thermal spray powder is 0.480 or less, 0.460 or less, 0.440 or less, 0.420 or less, less than 0.417, 0.400 or less, 0.380 or less, 0.360 or less, less than 0.360, 0.340 or less, 0.320 or less, 0.300 or less, 0.290 or less, 0.280 or less, 0.270 or less, less than 0.269, 0.260 or less, 0.250 or less, 0.240 or less, 0.230 or less, 0.220 or less, or 0.210 or less. By appropriately adjusting the upper limit of the dispersion index of the thermal spray powder, the value of the powder cross-sectional porosity of the thermal spray powder can be reduced, thereby further suppressing the generation of particles due to coating corrosion.

[0036] In one embodiment of the present invention, the dispersion index of the thermal spray powder is 0.100 or higher, 0.120 or higher, 0.140 or higher, 0.160 or higher, 0.180 or higher, 0.200 or higher, 0.220 or higher, 0.240 or higher, greater than 0.250, or 0.260 or higher. By appropriately adjusting the lower limit of the dispersion index of the thermal spray powder, the value of the powder cross-sectional porosity of the thermal spray powder can be reduced, thereby further suppressing the generation of particles due to coating corrosion.

[0037] In one embodiment of the present invention, the dispersion index of the thermal spray powder is less than 0.360, and the volume-based cumulative 90% particle size (D90) is greater than 39.0 μm. This embodiment makes it possible to reduce the value of the powder cross-sectional porosity of the thermal spray powder, and consequently further suppress the generation of particles due to coating corrosion.

[0038] (Content of particles with a particle diameter of less than 38 μm) In one embodiment of the present invention, the content of particles with a particle diameter of less than 38 μm in the thermal spray powder is 51.70 volume% or less, 40.00 volume% or less, 30.00 volume% or less, 28.00 volume% or less, 26.00 volume% or less, 24.00 volume% or less, 22.00 volume% or less, 20.00 volume% or less, 18.00 volume% or less, less than 17.38 volume%, 16.00 volume% or less, 14.00 volume% or less, 12.00 volume% or less, or 10.00 volume% or less. In one embodiment of the present invention, the content of particles with a particle size of less than 38 μm in the thermal spray powder is 8.00 volume% or more, 10.00 volume% or more, 12.00 volume% or more, 14.00 volume% or more, 16.00 volume% or more, more than 16.98 volume%, 18.00 volume% or more, 20.00 volume% or more, 22.00 volume% or more, 24.00 volume% or more, or 26.00 volume% or more. The content of particles with a particle size of less than 38 μm in the thermal spray powder can be measured, for example, using a laser diffraction particle size distribution analyzer.

[0039] (Content of particles with a particle diameter of less than 32 μm) In one embodiment of the present invention, the content of particles with a particle diameter of less than 32 μm in the thermal spray powder is less than 37.00 volume%, 30.00 volume% or less, 20.00 volume% or less, 10.00 volume% or less, 9.00 volume% or less, 8.00 volume% or less, 7.00 volume% or less, 6.00 volume% or less, 5.00 volume% or less, less than 4.05 volume%, 4.00 volume% or less, or 3.00 volume% or less. In one embodiment of the present invention, the content of particles with a particle size of less than 32 μm in the thermal spray powder is 0.50 volume% or more, 1.00 volume% or more, 1.50 volume% or more, 2.00 volume% or more, 2.50 volume% or more, 3.00 volume% or more, more than 3.61 volume%, 4.00 volume% or more, 4.50 volume% or more, 5.00 volume% or more, 5.50 volume% or more, or 6.00 volume% or more. The content of particles with a particle size of less than 32 μm in the thermal spray powder can be measured, for example, using a laser diffraction particle size distribution analyzer.

[0040] (Content of particles with a particle diameter of less than 25 μm) In one embodiment of the present invention, the content of particles with a particle diameter of less than 25 μm in the thermal spray powder is less than 19.51 volume%, 15.00 volume% or less, 10.00 volume% or less, 5.00 volume% or less, 2.00 volume% or less, 1.00 volume% or less, 0.80 volume% or less, 0.60 volume% or less, 0.40 volume% or less, 0.20 volume% or less, less than 0.11 volume%, 0.10 volume% or less, 0.09 volume% or less, 0.07 volume% or less, 0.05 volume% or less, 0.03 volume% or less, or 0.02 volume% or less. In one embodiment of the present invention, the content of particles with a particle size of less than 25 μm in the thermal spray powder is 0.01 volume% or more, 0.03 volume% or more, 0.05 volume% or more, more than 0.06 volume%, 0.07 volume% or more, 0.08 volume% or more, 0.10 volume% or more, 0.20 volume% or more, or 0.30 volume% or more.

[0041] (Content of particles with a particle size of less than 20 μm) In one embodiment of the present invention, the content of particles with a particle size of less than 20 μm in the thermal spray powder is less than 9.40 volume%, 3.00 volume% or less, 1.00 volume% or less, 0.50 volume% or less, 0.40 volume% or less, 0.30 volume% or less, 0.20 volume% or less, 0.05 volume% or less, or less than 0.01 volume%. The content of particles with a particle size of less than 25 μm in the thermal spray powder can be measured, for example, using a laser diffraction particle size distribution analyzer.

[0042] (Powder Cross-Sectional Porosity) The powder cross-sectional porosity of the thermal spray powder disclosed herein is 30% or less. Powder cross-sectional porosity is the ratio of the voids between the multiple primary particles constituting the thermal spray powder to the cross-section of the thermal spray powder, and is calculated by taking images using a scanning electron microscope and using image analysis software. Specifically, it is calculated by the measurement method described in the examples. Because the powder cross-sectional porosity of the thermal spray powder disclosed herein is significantly low, the coatings produced using it have fewer voids and are denser. Therefore, the corrosion resistance of the coating is improved and particle generation can be suppressed. In order to make the powder cross-sectional porosity of the thermal spray powder 30% or less, as will be described later, it is preferable to adjust the average primary particle size of the raw material powder (raw material powder) used to produce the thermal spray powder.

[0043] According to one embodiment of the present invention, the porosity of the powder cross-section of the thermal spray powder is 29.0% or less, 28.0% or less, 27.0% or less, 26.0% or less, 25.0% or less, 24.0% or less, 23.0% or less, 22.0% or less, 21.0% or less, 20.0% or less, 19.0% or less, 18.0% or less, or 17.0% or less. By making the porosity of the powder cross-section of the thermal spray powder smaller, the voids in the coating made using it become smaller and denser, improving the corrosion resistance of the coating and further suppressing the generation of particles. In particular, if the porosity of the powder cross-section of the thermal spray powder is less than 18.0% or 17.0% or less, the generation of particles due to coating corrosion can be further suppressed. According to one embodiment of the present invention, the porosity of the powder cross-section of the thermal spray powder is, for example, 15.0% or more, 16.0% or more, 17.0% or more, 18.0% or more, 19.0% or more, or 20.0% or more. According to one embodiment of the present invention, the porosity of the powder cross-section of the thermal spray powder is 15.0% or more and 30.0% or less, or 16.0% or more and 25.0% or less.

[0044] (Bulk density) According to one embodiment of the present invention, the bulk density of the thermal spray powder is 1.50 g / cm³. ３ Super, 1.52g / cm ３ Above, 1.54g / cm ３ Above, 1.56g / cm ３ Above, 1.58g / cm ３ Above, 1.60g / cm ３ Above, 1.62g / cm ３ Above, 1.64g / cm ３ Above, 1.66g / cm ３ Above, 1.68g / cm ３ Above, 1.70g / cm ３ Above, 1.72g / cm ３ Above, 1.74g / cm ３ Above, 1.76g / cm ３ Above, 1.78g / cm ３ Above, 1.80g / cm ３ Above, 1.82g / cm ３ Above, 1.84g / cm ３ Above, 1.86g / cm ３not less than 1.87 g / cm ３ more than 1.88 g / cm ３ not less than, or 1.90 g / cm ３ not less than the above. The bulk specific gravity of the powder for thermal spraying (granules) refers to the density (specific gravity) calculated from the mass of the thermal spraying powder when a container of a predetermined capacity is filled with the thermal spraying powder in a naturally packed state, wherein the thermal spraying powder flows out spontaneously from an orifice with a diameter of 2.5 mm. The bulk specific gravity can be measured in accordance with the provisions of JIS Z2504:2012 "Metallic powders - Determination of apparent density". When the bulk specific gravity of the thermal spraying powder is appropriately increased, it has the effect of reducing the porosity in the cross-section of the powder. Therefore, a dense coating can be formed, and consequently the generation of particles caused by coating corrosion can be suppressed.

[0045] According to an embodiment of the present invention, the bulk specific gravity of the thermal spraying powder is 3.00 g / cm ３ not more than 2.50 g / cm ３ not more than 2.30 g / cm ３ not more than 2.10 g / cm ３ not more than 1.95 g / cm ３ not more than 1.93 g / cm ３ not more than 1.91 g / cm ３ less than 1.89 g / cm ３ not more than 1.86 g / cm ３ not more than 1.83 g / cm ３ not more than 1.80 g / cm ３ not more than 1.77 g / cm ３ not more than 1.74 g / cm ３ not more than, or 1.72 g / cm ３ not more than the above. When the bulk specific gravity of the thermal spraying powder is appropriately decreased, it has the effect of reducing the porosity in the cross-section of the powder. Therefore, a dense coating can be formed, and consequently the generation of particles caused by coating corrosion can be suppressed.

[0046] (Flowability) According to one embodiment of the present invention, the flowability of the thermal spray powder is 0.70 g / s or more, 0.75 g / s or more, 0.80 g / s or more, 0.85 g / s or more, 0.90 g / s or more, 0.95 g / s or more, greater than 1.00 g / s, 1.10 g / s or more, or 1.20 g / s or more. The flowability of the thermal spray powder (granules) can be measured, for example, in accordance with the "Metal powder - Method for measuring flowability" specified in JIS Z2502:2012. When the flowability of the thermal spray powder is appropriately high, it has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed. According to one embodiment of the present invention, the fluidity of the thermal spray powder is 3.00 g / s or less, 2.50 g / s or less, 2.00 g / s or less, 1.80 g / s or less, 1.60 g / s or less, 1.40 g / s or less, 1.20 g / s or less, less than 1.12 g / s, 1.10 g / s or less, 1.05 g / s or less, 1.00 g / s or less, or 0.95 g / s or less. When the fluidity of the thermal spray powder is appropriately low, it has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed.

[0047] (Angle of Repose) According to one embodiment of the present invention, the angle of repose of the thermal spray powder is less than 38.0°, 36.0° or less, 34.0° or less, 32.0° or less, 30.0° or less, less than 28.3°, or 28.0° or less. In this specification, "angle of repose" means the base angle calculated from the diameter and height of a cone-shaped deposit formed by dropping thermal spray powder from a funnel of a certain height onto a horizontal substrate. The angle of repose can be measured in accordance with the provisions of JIS R9301-2-2:1999 "Method for measuring the physical properties of alumina powder - 2: Angle of repose". The specific method for measuring the angle of repose is as described in the examples. When the angle of repose of the thermal spray powder is appropriately small, it has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed. According to one embodiment of the present invention, the angle of repose of the thermal spray powder is 20.0° or higher, 22.0° or higher, 24.0° or higher, 26.0° or higher, 27.0° or higher, greater than 27.1°, 27.3° or higher, 28.0° or higher, or 29.0° or higher. Having an appropriate lower limit for the angle of repose of the thermal spray powder makes it possible to lower the porosity of the powder cross-section. A moderately large angle of repose of the thermal spray powder has the effect of reducing the porosity of the powder cross-section. As a result, a dense coating can be formed, and consequently, the generation of particles due to coating corrosion can be suppressed.

[0048] <Method for Manufacturing Thermal Spray Powder> A preferred embodiment of the method for manufacturing thermal spray powder disclosed herein will be outlined below. Although not limited thereto, a slurry is prepared by mixing raw material powder and a dispersion medium in a mixer. Next, granulated powder is prepared from the slurry using, for example, a spray dryer. The granulated powder thus obtained is sintered to obtain a sintered body, which is then crushed and classified to produce the thermal spray powder.

[0049] [Slurry Preparation Process] This process involves preparing the slurry.

[0050] The raw material powder can be prepared by selecting the powder for thermal spraying to have a desired composition. In one embodiment of the present invention, the average primary particle size of the raw material powder is 0.1 to 3.0 μm, 0.2 to 2.7 μm, 0.3 to 2.5 μm, 0.4 to 2.2 μm, 0.5 to 2.0 μm, 0.6 to 2.0 μm, 0.7 to 2.0 μm, 0.8 to 2.0 μm, or 1.0 to 2.0 μm. By having the average primary particle size of the powder for thermal spraying within this range, the powder cross-sectional porosity can be controlled to 30.0% or less.

[0051] The average primary particle size of the raw material powder can be measured by the method described in the examples.

[0052] There are no particular restrictions on the dispersion medium to be mixed with the raw material powder, but examples include water and alcohol (for example, C1, C2, or C3). In one embodiment of the present invention, the amount of dispersion medium (for example, water) is 20 parts by mass or more and 30 parts by mass or less per 100 parts by mass of the total amount of raw material powder. In one embodiment of the present invention, the raw material powder may be mixed with any additive such as a binder or dispersant. Examples of binders include polyvinyl butyral resin (PVB), polyvinyl alcohol resin (PVA), polyvinyl acetate resin, and polyacrylic resin. The amount of any additive added is set so as not to hinder the intended effect of the present invention. The dispersant may be a polymeric dispersant, a surfactant-type dispersant (also called a low molecular weight dispersant), or an inorganic dispersant, and these may be anionic, cationic, or nonionic.

[0053] [Granulation Process] This process is for producing granulated powder. Examples of granulation methods for producing granulated powder include rolling granulation, fluidized bed granulation, agitation granulation, stirring granulation, crushing granulation, melt granulation, spray granulation, and microemulsion granulation. Among these, spray granulation is preferred. In spray granulation, droplets are formed from the slurry. The droplets are carried by an airflow and passed through a spray dryer to produce granulated powder.

[0054] [Sintering Process] This process is a process for producing a sintered body by firing granulated powder. In one embodiment of the present invention, the sintering temperature of the granulated powder is 1000°C or higher, 1400°C or higher, or 1500°C or higher. In one embodiment of the present invention, the sintering temperature of the granulated powder is 1900°C or lower. In one embodiment of the present invention, the sintering temperature of the granulated powder is 1000°C or higher and 1900°C or lower. In one embodiment of the present invention, the sintering time of the granulated powder can be 1 hour or more, 2 hours or more, 4 hours or more, 6 hours or more, or 12 hours or more. In one embodiment of the present invention, the sintering time of the granulated powder is usually 24 hours or less. In one embodiment of the present invention, the sintering time of the granulated powder is 1 hour or more and 24 hours or lower.

[0055] [Disintegration Process] This process involves disintegrating the sintered body. The disintegration process is, for example, a process of disintegrating the sintered body. The sintered body can be disintegrated, for example, by a crusher. Examples of crushers used include jaw crushers, cone crushers, hammer crushers, roll crushers, and millstone crushers. The degree of disintegration of the sintered body can be appropriately set, for example, so that the resulting thermal spray powder is more likely to have the desired particle size distribution.

[0056] [Classification Process] This process is for classifying the crushed sintered body. In one embodiment of the present invention, the crushed sintered body may be classified such that the volume-based cumulative 50% particle size (D50) of the resulting thermal spray powder is 35.0 μm or larger. Preferably, the classification is performed by sieving, and more specifically, it is preferable to take the crushed sintered body with a sieve with a mesh size of 38 μm on it, and even more preferable to pass the crushed sintered body through a sieve with a mesh size of 75 μm and then take the crushed sintered body with a sieve with a mesh size of 38 μm on it.

[0057] It is preferable to manufacture the thermal spray powder in the manner described above.

[0058] <Applications of Thermal Spray Powder> By spraying the thermal spray powder disclosed herein using various thermal spraying methods, thermal spray coatings can be produced on various substrates. The thermal spray powder can be particularly preferably used to produce thermal spray coatings using plasma spraying methods such as atmospheric plasma spraying (APS), low-pressure plasma spraying (LPS), and high-pressure plasma spraying. Furthermore, the spraying powder can also be suitably used in other high-velocity flame spraying methods, such as oxygen-supported high-velocity flame (HVOF) spraying, warm spray spraying, and air-supported high-velocity air flame (HVAF) spraying. The spraying powder may be supplied to the spraying apparatus in powder form, or in slurry form dispersed in a suitable dispersion medium.

[0059] The type of substrate used to produce the thermal spray coating is not particularly limited. Examples of substrates include aluminum, aluminum alloys, iron, steel, copper, copper alloys, nickel, nickel alloys, gold, silver, bismuth, manganese, zinc, zinc alloys, etc. Among these, preferred substrates are steels such as various SUS materials (which may be so-called stainless steels) used as corrosion-resistant structural steels, aluminum alloys such as the 1000 series to 7000 series aluminum alloys that are useful as lightweight structural materials, and corrosion-resistant alloys of Ni, Co, and Fe groups such as Hastelloy, Inconel, Stellite, and Invar.

[0060] As described above, the thermal spray powder disclosed herein is suitably used for producing thermal spray coatings. Therefore, this specification provides a method for producing a thermal spray coating by thermal spraying the thermal spray powder disclosed herein onto the surface of a substrate.

[0061] The present invention encompasses the following embodiments and forms.

[0062] 1. A powder for thermal spraying having a volume-based cumulative 50% particle size (D50) of 35.0 μm or more and a powder cross-sectional porosity of 30.0% or less.

[0063] 2. The thermal spray powder described in 1., wherein the powder cross-sectional porosity is 15.0% or more.

[0064] 3. A thermal spray powder as described in 1. or 2., wherein the span value is less than 1.000, 0.8 or less, or 0.7 or less.

[0065] 4. A thermal spray powder according to any of 1 to 3, wherein the volume-based cumulative 90% particle size (D90) is greater than 45.0 μm.

[0066] 5. A thermal spray powder as described in any of 1 to 4, having an angle of repose of less than 38.0°.

[0067] 6. A thermal spray powder according to any of 1 to 5, wherein the dispersion index is less than 0.360 and the volume-based cumulative 90% particle size (D90) is greater than 39.0 μm.

[0068] 7. A thermal spray powder according to any one of 1 to 6, wherein the volume-based cumulative 50% particle size (D50) is 55.0 μm or less.

[0069] 8. A thermal spray powder according to any one of 1 to 7, wherein the volume-based cumulative 50% particle size (D50) is 40.0 μm or larger.

[0070] 9. A thermal spray powder according to any of 1 to 8, wherein the content of particles with a particle size of 75 μm or larger is 0.50% by mass or less, 0.10% by mass or less, or less than 0.02% by mass.

[0071] 10. A thermal spray powder containing rare earth elements, as described in any of 1 to 9.

[0072] 11. The thermal spray powder described in 10, comprising yttrium (Y) as the rare earth element.

[0073] 12. A thermal spray powder according to any of 1 to 11, wherein the volume-based cumulative 50% particle size (D50) is 35.0 μm or more and 67.0 μm or less, 40.0 μm or more and 50.0 μm or less, or greater than 46.6 μm and less than 46.8 μm.

[0074] 13. A thermal spray powder according to any of 1 to 12, wherein the volume-based cumulative 5% particle size (D5) is 17.0 μm or more and 45.0 μm or less, 25.0 μm or more and 46.0 μm or less, or greater than 31.9 μm and less than 32.9 μm.

[0075] 14. A thermal spray powder according to any of 1 to 13, wherein the volume-based cumulative 10% particle size (D10) is 21.0 μm or more and 54.0 μm or less, 29.0 μm or more and 46.0 μm or less, or greater than 34.6 μm and less than 35.7 μm.

[0076] 15. A thermal spray powder according to any of 1 to 14, wherein the volume-based cumulative 90% particle size (D90) is 42.0 μm or more and 69.0 μm or less, 50.0 μm or more and 68.5 μm or less, or greater than 60.6 μm and less than 61.5 μm.

[0077] 16. A thermal spray powder according to any of 1 to 15, wherein the volume-based cumulative 95% particle size (D95) is 50.0 μm or more and 75.0 μm or less, 55.0 μm or more and 71.0 μm or less, or greater than 65.0 μm and less than 65.8 μm.

[0078] 17. A thermal spray powder according to any of 1 to 16, wherein the content of particles with a particle size of 75 μm or larger is 0.40% by mass or less, 0.08% by mass or less, or less than 0.02% by mass.

[0079] 18. A thermal spray powder according to any of 1 to 17, wherein the content of particles with a particle size of 63 μm or larger is greater than 0% by mass and less than or equal to 10.00% by mass, 0.03% by mass and less than or equal to 7.20% by mass, or greater than 0.12% by mass and less than 0.48% by mass.

[0080] 19. A thermal spray powder according to any of 1 to 18, wherein the content of particles with a particle size of 53 μm or larger is 5.00% by mass or more and 40.00% by mass or less, 9.00% by mass or more and 36.00% by mass or less, or more than 13.57% by mass and less than 20.44% by mass.

[0081] 20. A thermal spray powder according to any of 1 to 19, wherein the span value is 0.3 or more and 0.9 or less, 0.4 or more and 0.8 or less, or 0.6 or more and 0.9 or less.

[0082] 21. A thermal spray powder according to any of 1 to 20, wherein the variance index is 0.100 or more and less than 0.481, 0.200 or more and less than 0.417, 0.220 or more and less than 0.360, or greater than 0.250 and less than 0.269.

[0083] 22. A thermal spray powder according to any of 1 to 21, wherein the content of particles with a particle size of less than 38 μm is 8.0% by volume or more and 51.7% by volume or less, 9.0% by volume or more and 28.0% by volume or less, or 15.0% by volume or more and 18.00% by volume or less.

[0084] 23. A thermal spray powder according to any of 1 to 22, wherein the content of particles with a particle size of less than 32 μm is 0.5 volume% or more and less than 37.0 volume%, 1.5 volume% or more and 7.0 volume%, or more than 3.6 volume% and less than 4.1 volume%.

[0085] 24. A thermal spray powder according to any of 1 to 23, wherein the content of particles with a particle size of less than 25 μm is 0.01 volume% or more and less than 19.5 volume%, 0.03 volume% or more and 1.00 volume%, or 0.05 volume% or more and 0.40 volume%.

[0086] 25. A thermal spray powder according to any of 1 to 24, wherein the content of particles with a particle size of less than 20 μm is less than 9.4 volume%, 3.0 volume% or less, 1.00 volume% or less, or 0.3 volume% or less.

[0087] 26. A thermal spray powder according to any of 1 to 25, wherein the powder cross-sectional porosity is 25.0% or less, 22.0% or less, 18.0% or less, or less than 18.0%.

[0088] 27. A thermal spray powder according to any of 1 to 26, wherein the powder cross-sectional porosity is 15.0% or more and 25.0% or less, 16.0% or more and 22.0% or less, or 16.0% or more and less than 18.0%.

[0089] 28. The bulk density is 1.5 g / cm³. ３ Super 3.00g / cm ３ Below, 1.60g / cm ３ 2.30g / cm or more ３ Below, 1.70g / cm ３ 2.10g / cm or more ３The following, or 1.87 g / cm³ ３ Super 1.91g / cm ３ A thermal spray powder described in any of items 1 to 27, which is less than [amount missing].

[0090] 29. A thermal spray powder according to any of 1 to 28, wherein the fluidity is 0.70 g / s or more and 3.00 g / s or less, 0.85 g / s or more and 2.00 g / s or less, or greater than 1.00 g / s and less than 1.10 g / s.

[0091] 30. A thermal spray powder according to any of 1 to 29, wherein the angle of repose of the thermal spray powder is 20.0° or more and less than 38.0°, 24.0° or more and 30.0° or less, or greater than 27.1° and less than 28.3°.

[0092] 31. A method for producing a thermal spray coating by thermal spraying a thermal spray powder described in any of 1 to 30 onto the surface of a substrate.

[0093] The present invention will be further described below with reference to examples and comparative examples.

[0094] <Preparation of thermal spray slurry> (Example 1) Water and Y as raw material powder ２ O ３A slurry was prepared by mixing powder (average primary particle size: 1.0 μm) and a binder so that the concentration of the raw material powder was 50% by mass. The slurry was then dried and granulated using a spray dryer to produce granulated powder. The granulated powder was then solid-phase sintered at a sintering temperature of 1600°C for 6 hours to obtain a sintered body. The sintered body was then crushed, and the sintered body with a mesh opening (JIS Z 8801-1:2019 nominal mesh opening) of 75 μm was passed through and a mesh opening of 38 μm was passed through using a vibrating sieve to obtain thermal spray powder (granules) having the particle size distribution shown in Table 1. The average primary particle size of the raw material powder was measured using cross-sectional images obtained by observing the cross-section of the particles with a scanning electron microscope (SEM). Specifically, a statistically reliable number of primary particles (e.g., 20, 100, or 300) were randomly selected from the primary particles in the SEM image obtained using a scanning electron microscope (SEM). The average primary particle diameter was then calculated by dividing the sum of the primary particle diameters of the selected particles by the number of selected particles.

[0095] [Volume-based cumulative particle size distribution] The volume-based particle size distribution was measured using a laser diffraction particle size analyzer (Mastersiszer 3000, manufactured by Malvern Panalogical). In this particle size distribution, the particle sizes were obtained at cumulative values ​​of 5 volume%, 10 volume%, 50 volume%, 90 volume%, and 95 volume%, respectively, and are shown in the "D5", "D10", "D50", "D90", and "D95" columns in Table 1. In addition, the "-38 μm", "-32 μm", "-25 μm", and "-20 μm" columns in Table 1 show the results of measuring the ratio of particle sizes of 38.0 μm or less, 32.0 μm or less, 25.0 μm or less, and 20.0 μm or less to the cumulative volume of the thermal spray powder (granules) using the same device. More specifically, in Table 1, the content of particles with a diameter of less than 38 μm is indicated as "-38 μm", the content of particles with a diameter of less than 32 μm is indicated as "-32 μm", the content of particles with a diameter of less than 25 μm is indicated as "-25 μm", and the content of particles with a diameter of less than 20 μm is indicated as "-20 μm".

[0096] [Particle Distribution of Coarse Particles] The "+75μm", "+63μm", and "+53μm" columns in Table 1 show the results of measuring the ratio of the cumulative mass of particles with particle diameters of 75.0 μm or larger, 63.0 μm or larger, and 53.0 μm or larger to the cumulative mass of the thermal spray powder (granules). A rotap-type sieve shaker manufactured by Teraoka Corporation (see JIS Z 8801-1:2019) was used for this measurement. More specifically, in Table 1, the content of particles with a particle diameter of 75 μm or larger is indicated as "+75 μm", the content of particles with a particle diameter of 63 μm or larger is indicated as "+63 μm", and the content of particles with a particle diameter of 53 μm or larger is indicated as "+53 μm".

[0097] (Examples 2-9) By changing the spray dryer conditions to obtain the particle size distribution shown in Table 1, we obtained sprayable powder (granules) having the particle size distribution shown in Table 1.

[0098] (Comparative Examples 1-4) Except for not using a sieve with a mesh size of 38 μm and changing the spray dryer conditions to achieve the particle size distribution shown in Table 1, thermal spray powder (granules) having the particle size distribution shown in Table 1 were obtained in the same manner as in Example 1.

[0099] [Powder Cross-Sectional Porosity] Small pieces were prepared by mixing thermal spray powder with epoxy resin-based chemical reaction adhesive and solidifying them. The surface of the small pieces was smoothed using JEOL Handy Wrap (HLA-2), and the cross-section was prepared using JEOL CROSS SECTION POLISHER (model number: IB-19530CP). The test pieces were imaged at a magnification of 5000 using a Thermo Fisher Scientific desktop scanning electron microscope (model number: Phenom Prox). Subsequently, the cross-sectional porosity was calculated using image analysis software on a Keyence microscope (model number: VHX-5000). The porosity of 50 powder particles was randomly calculated and the average value was used.

[0100] [Bulk density] Bulk density (g / cm³) ３ The bulk density (g / cm³) was measured in accordance with JIS Z2504:2012. ３ The values ​​obtained by subjecting each thermal spray powder to a JIS bulk density meter for metal powders (manufactured by Tsutsui Rikagakukikai Co., Ltd.) are shown in the corresponding column in Table 1. ３This shows the value of ).

[0101] [Flowability] The flowability of the thermal spray powder (granules) was measured in accordance with the "Metal powder - Flowability measurement method" specified in JIS Z2502:2012. Specifically, a test funnel was fixed to a funnel support, and 50 g of powder was supplied to the funnel with the orifice closed. Then, the orifice was opened, and the time required for all the powder to flow out of the orifice was measured. The flowability was calculated by dividing this time (seconds) by 50 g.

[0102] [Angle of Repose] The angle of repose for the thermal spray powders was measured in accordance with JIS R9301-2-2:1999. The angle of repose was obtained by subjecting each thermal spray powder to the A.B.D. Powder Properties Analyzer (Tsutsui Rikakikai Co., Ltd., ABD-72 model). The measured angle of repose values ​​are shown in the corresponding column in Table 1.

[0103] <Preparation of Spray Specimens> A spray coating was prepared using spray powder by APS (Atmospheric Plasma Spraying). In this example, a plate made of aluminum alloy (Al6061) (70 mm x 50 mm x 2.3 mm) was used as the substrate, without blast treatment and in a mirror-like state. In this example, after sufficient preheating with plasma generated in the spraying machine, the spray powder was supplied, and one scan was performed with the spray gun moving at a speed of 1500 mm / second, with the plasma irradiation angle to the substrate set to 90 degrees. The spray distance was set to 120 mm. The above "spray distance" in relation to the preparation of the spray coating refers to the distance from the tip of the spray gun to the substrate.

[0104] [Conditions] Substrate: Aluminum alloy (Al6061) (70mm x 50mm x 2.3mm) Thermal sprayer: SG-100 (Praxair) Powder feeder: Model 1264 (Praxair) Plasma working gas: Ar gas pressure: 50 psi (0.34 MPa) He gas pressure: 50 psi (0.34 MPa) Plasma output: 36 kW Voltage: 40 V Current: 900 A Speed: 1500 mm / sec Spray distance: 120 mm Plasma irradiation angle: 90 degrees Spray powder supply rate: 5 g / min.

[0105] [Splat Size, Microscopic Images of Splats] The prepared splat specimens were photographed at 200x magnification using a KEYENCE microscope (model: VHX-5000), and the diameter of the flattened splat (referring to the straight-line distance between the longest opposing points connecting two points on the outer circumference of the splat) was measured using image analysis software. Figure 1 shows a microscopic image of the splat specimen of Example 2 at 200x magnification, and Figure 2 shows a microscopic image of the splat specimen of Comparative Example 3 at 200x magnification.

[0106] Since splatters are formed by spraying molten thermal spray powder onto a substrate, their shape, as shown in Figures 1 and 2, consists of numerous irregular protrusions and sharp points extending outward from the outer circumference. However, in the image analysis software described above, the shape of the splatter is treated as a virtual circle or ellipse, eliminating the protrusions and points, thereby automatically obtaining information about the outer circumference.

[0107] Fifty splatters were measured randomly, and the coefficient of variation was calculated from the mean and standard deviation. Note that the number of splatters per image varies depending on the particle size of the thermal spray powder, so it may be necessary to increase the number of fields of view as needed. For example, it is preferable to adjust the number of splatters to 20 to 50 per field of view.

[0108]

[0109] This application is based on Japanese Patent Application No. 2025-056392, filed on 28 March 2025, the disclosures thereof being incorporated herein by reference in their entirety.

Claims

1. A powder for thermal spraying having a volume-based cumulative 50% particle size (D50) of 35.0 μm or larger, and a powder cross-sectional porosity of 30.0% or less.

2. The thermal spray powder according to claim 1, wherein the porosity of the powder cross-section is 15.0% or more.

3. The thermal spray powder according to claim 1 or 2, wherein the span value is less than 1.

0.

4. The thermal spray powder according to claim 1 or 2, wherein the volume-based cumulative 90% particle size (D90) is greater than 45.0 μm.

5. The thermal spray powder according to claim 1 or 2, wherein the angle of repose is less than 38.0°.

6. The thermal spray powder according to claim 1 or 2, wherein the dispersion index is less than 0.360 and the volume-based cumulative 90% particle size (D90) is greater than 39.0 μm.

7. The thermal spray powder according to claim 1 or 2, wherein the volume-based cumulative 50% particle size (D50) is 55.0 μm or less.

8. The thermal spray powder according to claim 1 or 2, wherein the volume-based cumulative 50% particle size (D50) is 40.0 μm or larger.

9. The thermal spray powder according to claim 1 or 2, wherein the content of particles with a particle size of 75 μm or larger is 0.50% by mass or less.

10. A thermal spray powder according to claim 1 or 2, which contains a rare earth element.

11. The thermal spray powder according to claim 10, wherein the rare earth element is yttrium (Y).

12. A method for producing a thermal spray coating by thermal spraying the thermal spray powder described in claim 1 or 2 onto the surface of a substrate.

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