Powder for film formation and film using same

Abstract

[Problem] To provide a powder for film formation, the powder being capable of forming a dense film. [Solution] A powder for film formation, the powder having a specific surface area of greater than or equal to 2.5 m2 / g and a volume-based cumulative 50% particle diameter (D50) of less than 10 μm.

Description

Film-forming powder and coatings using the same

[0001] This invention relates to a film-forming powder and a film using the same.

[0002] Thin-film deposition technology, which imparts new functionality by coating the surface of a substrate with various materials, has been used in a wide range of fields, including semiconductors, solar cells, displays, and surface coatings. For example, thin-film deposition technology plays an important role in the manufacturing of semiconductor manufacturing equipment. In the manufacturing of semiconductor manufacturing equipment, the electrical properties of semiconductor devices are controlled by forming a fine thin film on a substrate (i.e., the deposition process). However, in the deposition process, especially in technologies using plasma, a problem called "erosion" can occur. Erosion is a phenomenon in which the deposition material or a part of the equipment is gradually scraped away by the plasma, which can lead to a decrease in the durability of the equipment and a loss of uniformity in the deposition. To address this problem, various technological approaches are required, such as the development of protective films that are resistant to erosion and the optimization of equipment design.

[0003] For example, a method has been proposed to form a thermal spray coating made of ceramics or other materials by melting a powder made of ceramics or other materials using combustion energy or electrical energy and spraying it onto the surface of a substrate (for example, Japanese Patent Application Publication No. 2021-102546). Such thermal spray coatings are used as protective films for semiconductor manufacturing equipment and are known to reduce problems caused by erosion.

[0004] However, current technologies have not been able to produce coatings with sufficient erosion resistance, and this remains an area that needs improvement. To achieve such erosion resistance, it is necessary to improve the density of the coating.

[0005] Therefore, the present invention aims to provide a film-forming powder that can form a dense film in film-forming technology.

[0006] The inventors diligently studied to solve the above problems. As a result, the inventors discovered that the above problems can be solved by the following means, and thus completed the present invention.

[0007] In other words, the above problem of the present invention is that the specific surface area is 2.5 m². ２ This can be solved with a film-forming powder that has a concentration of 1 / g or more and a volume-based cumulative 50% particle size (D50) of less than 10 μm.

[0008] The present invention provides a film-forming powder capable of forming a dense film.

[0009] The embodiments of the present invention will be described below. The embodiments shown herein are illustrative examples to embody the technical idea of ​​the present invention and do not limit the invention. Therefore, all other implementable forms, methods of use, and operating techniques that can be conceived by those skilled in the art without departing from the spirit of the present invention are included in the scope and spirit of the present invention, as well as in the claims and their equivalents. The embodiments described herein can be arbitrarily combined to form other embodiments.

[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, respectively. In this specification, unless otherwise specified, operations and measurements of physical properties, etc., are performed under conditions of room temperature (20°C to 25°C) and relative humidity of 40% RH to 50% RH. Furthermore, if a feature or aspect of this disclosure is described in terms of the Markush group, a person skilled in the art will recognize that this disclosure is described in terms of any individual component or subgroup of components of the Markush group. It should also be understood that all embodiments and combinations of descriptions disclosed in this specification are disclosed in this application; that is, they should be understood as grounds for amendment.

[0011] One aspect of the present invention is a specific surface area of ​​2.5 m² ２ This is a film-forming powder having a particle size of 1 / g or more and a volume-based cumulative 50% particle size (D50) of less than 10 μm. A dense film can be formed using this film-forming powder.

[0012] [Powder for film formation] One aspect of the present invention is a powder with a specific surface area of ​​2.5 m². ２This is a film-forming powder having a particle size of 1 / g or more and a volume-based cumulative 50% particle size (D50) of less than 10 μm. In this specification, a high specific surface area (e.g., 2.5 m²) which has not been disclosed at all in the conventional specification is used. ２ By focusing on a new powder that has a particle size of 1 / g or more and a small particle size (for example, 10 μm or less), a novel film-forming powder with excellent properties is provided.

[0013] According to one embodiment of the present invention, the film-forming powder may contain particles made of ceramics. Examples of ceramics include oxide ceramics made of oxides of various metals, carbide ceramics made of carbides of various metals, nitride ceramics made of nitrides of various metals, or non-oxide ceramics made of non-oxides such as borides, fluorides, hydroxides, carbonates, and phosphates of various metals. Oxide ceramics are preferable in order to protect the semiconductor device itself from etching by plasma in the etching process of semiconductor manufacturing.

[0014] Examples of metal elements constituting 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 rare earth elements such as La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and scandium group rare earth elements such as Sc and Y; one or more selected from the foregoing may be mentioned. Among these, in order to protect the semiconductor device itself from plasma etching in the etching step of semiconductor manufacturing, the film-forming powder preferably contains a rare earth element, more preferably contains a lanthanide rare earth element or a scandium group rare earth element, further preferably contains a gadolinium (Gd) element, ytterbium (Yb) element, yttrium (Y) element, scandium (Sc) element, erbium (Er) element, holmium (Ho) element, or lutetium (Lu) element, and particularly preferably contains a gadolinium (Gd) element, ytterbium (Yb) element, or yttrium (Y) element.

[0015] According to one embodiment of the present invention, examples of the oxide-based ceramic include alumina (Al ２ O ３ ), zirconia (ZrO ２ ), gadolinium oxide (Gd ２ O ３ ), ytterbium oxide (Yb ２ O ３ ), yttria (Y ２ O ３ ), chromia (Cr ２ O ３ ), titania (TiO ２ ), magnesia (MgO), silica (SiO ２ ), calcia (CaO), ceria (CeO ２ ), and other single oxides. Among these, in order to protect the semiconductor device itself from plasma etching in the etching step of semiconductor manufacturing, gadolinium oxide (Gd ２ O ３ ), ytterbium oxide (Yb２ O ３ ), Yttria (Y ２ O ３ ) is preferred. Gadolinium oxide (Gd ２ O ３ ), ytterbium oxide (Yb ２ O ３ ), and Yttria (Y ２ O ３ ) usually forms a white thermal spray coating. And gadolinium oxide (Gd ２ O ３ ), ytterbium oxide (Yb ２ O ３ ), and Yttria (Y ２ O ３ ) is a preferred material for forming a thermal spray coating having erosion resistance to plasma. For example, gadolinium oxide (Gd), which is the film-forming powder of this embodiment, can be used on the anodized surface of a high-purity aluminum alloy processing chamber surface or the surface of a processed part. ２ O ３ ), ytterbium oxide (Yb ２ O ３ ), or Yttria (Y ２ O ３ By forming a film using ), a highly dense film is formed, and excellent erosion resistance is obtained. According to one embodiment of the present invention, the film-forming powder is a monooxide consisting of an oxide of a single metal element. According to one embodiment of the present invention, the film-forming powder does not contain rare earth fluorides.

[0016] According to one embodiment of the present invention, the oxide ceramic may be a composite oxide. For example, the film-forming powder may be yttria (Y ２ O ３ ) and alumina (Al ２ O ３The 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 O ３ It can be produced by mixing and firing in a ratio of 31.1% by mass.

[0017] 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 Examples thereof include the above. The use of such rare earth silicates has the effect of expanding the range of options for applicable semiconductor products.

[0018] [Specific surface area (SA) of powder for film formation] The specific surface area (SA) of the powder for film formation disclosed in the present specification is 2.5 m ２ / g or more. Since the specific surface area (SA) of the powder for film formation is large, the film-forming property of a film formed using the same (for example, when thermal spraying or aerosol deposition is performed using the powder for film formation, the powder for film formation is easily melted and dispersed, and thermally sprayed particles or aerosolized particles can be closely packed during film formation (porosity is easily reduced), etc.) is also improved, and as a result, the denseness of the formed film is also improved. Therefore, the film formed using the powder for film formation disclosed in the present specification has improved erosion resistance. Therefore, even when the film is exposed to plasma in an etching step of semiconductor manufacturing, erosion of the film is suppressed, so particles generated due to erosion of the film can be suppressed.

[0019] In one embodiment of the present invention, the specific surface area (SA) of the powder for film formation is 2.6 m ２ / g or more, 2.7 m ２ / g or more, 2.8 m ２ / g or more, 3.0 m ２ / g or more, 3.2 m ２ / g or more, 3.5 m ２ / g or more, 4.0 m ２ / g or more, 4.5 m ２ / g or more, 5.0 m ２ / g or more, 5.5 m ２ / g or more, 6.0 m ２ / g or more, 6.5 m ２ / g or more, 7.0 m ２ / g or more, 7.5 m ２ / g or more, 8.0m ２ / g or more, or 8.2m ２ It is 1 / g or more. When the specific surface area (SA) of the film-forming powder is appropriately large, the film-forming properties (such as the ease with which the film-forming powder melts and disperses when thermal spraying or aerosol deposition is performed using the film-forming powder, and the ability of the thermally sprayed or aerosolized particles to be closely packed during film formation (making it easier to reduce pores)) are also improved, and a dense film can be formed. This suppresses film erosion, and consequently suppresses the generation of particles due to film erosion. According to one embodiment, the specific surface area (SA) of the film-forming powder is 5.0 m². ２ / g or more 10.0m ２ It is less than / g. According to one embodiment, the film-forming powder has a specific surface area of ​​5.0 m². ２ / g or more 10.0m ２ The particle size is less than or equal to / g, and the volume-based cumulative 50% particle size (D50) is 2.5 μm or less.

[0020] Here, the specific surface area (SA) of the film-forming powder is calculated by the BET method in accordance with the provisions of JIS Z 8830:2013 (ISO 9277:2010) "Method for measuring the specific surface area of ​​powders (solids) by gas adsorption," and can be measured specifically by the method described in the examples below.

[0021] [Particle size of film-forming powder] (Particle size (D50) of film-forming powder) The volume-based cumulative 50% particle size (D50) of the film-forming powder disclosed herein is less than 10 μm. Because the 50% particle size (D50) of the film-forming powder is small, the film-forming properties (such as the ease with which the film-forming powder melts and disperses when thermal spraying or aerosol deposition is performed using the film-forming powder, and the ability of the sprayed or aerosolized particles to be close-packed during film formation (making it easier to reduce pores)) are improved, and a dense film can be formed. This suppresses film erosion and, consequently, suppresses particles generated by film erosion.

[0022] In one embodiment of the present invention, the volume-based cumulative 50% particle size (D50) of the film-forming powder is 9.5 μm or less, 9.0 μm or less, 8.5 μm or less, 8.0 μm or less, 7.5 μm or less, 7.0 μm or less, 6.0 μm or less, 5.5 μm or less, 5.0 μm or less, 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, 2.5 μm or less, 2.3 μm or less, 2.2 μm or less, 2.1 μm or less, 2.0 μm or less, less than 2.0 μm, 1.9 μm or less, 1.8 μm or less, 1.7 μm or less, or 1.6 μm or less. When the volume-based cumulative 50% particle size (D50) of the film-forming powder becomes appropriately small, the effect of improving the density of the formed film is more pronounced. Therefore, a dense coating can be formed, and consequently, particles generated by erosion of the coating can be suppressed.

[0023] In one embodiment of the present invention, the volume-based cumulative 50% particle size (D50) of the film-forming powder is 0.01 μm or larger, 0.05 μm or larger, 0.1 μm or larger, 0.2 μm or larger, 0.3 μm or larger, 0.4 μm or larger, 0.5 μm or larger, 0.6 μm or larger, 0.7 μm or larger, 0.8 μm or larger, 0.9 μm or larger, 1.0 μm or larger, or greater than 1.0 μm. When the 50% particle size (D50) of the film-forming powder is moderately large, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by film erosion can be suppressed.

[0024] In one embodiment of the present invention, the volume-based cumulative 50% particle size (D50) of the film-forming powder is as follows: 0.01 μm or more and less than 10 μm, 0.05 μm or more and less than 10 μm, 0.1 μm or more and less than 10 μm, 0.01 μm or more and 9.0 μm or less, 0.01 μm or more and 7.0 μm or less, 0.01 μm or more and 6.0 μm or less, 0.05 μm or more and 5.5 μm or less, 0.05 μm or more and 5.0 μm or less, 0.05 μm or more. The particle sizes are 4.0 μm or less, 0.05 μm to 3.0 μm, 0.05 μm to 2.5 μm, 0.05 μm to 2.3 μm, 0.01 μm to 2.0 μm, 0.05 μm to 2.0 μm, 0.1 μm to 2.0 μm, 0.1 μm to less than 2.0 μm, 0.01 μm to 1.8 μm, 0.05 μm to 1.8 μm, or 0.1 μm to 1.8 μm. When the volume-based cumulative 50% particle size (D50) of the film-forming powder is within the above range, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by film erosion can be suppressed.

[0025] Here, the volume-based cumulative 50% particle size (D50) of the film-forming 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 film-forming powder using the laser diffraction scattering particle size distribution measurement method (also referred to simply as "D50" or "particle size (D50)" in this specification).

[0026] 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 the film-forming 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.

[0027] (Volume-based cumulative 5% particle size (D5) of film-forming powder) In one embodiment of the present invention, the volume-based cumulative 5% particle size (D5) of the film-forming powder is 0.001 μm or more, 0.005 μm or more, 0.01 μm or more, 0.02 μm or more, 0.03 μm or more, 0.0 μm or more, 0.05 μm or more, 0.08 μm or more, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, or 0.5 μm or more. When the volume-based cumulative 5% particle size (D5) of the film-forming powder is within the above range, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by erosion of the film can be suppressed.

[0028] In one embodiment of the present invention, the volume-based cumulative 5% particle size (D5) of the film-forming powder is 5.0 μm or less, 4.5 μm or less, 4.0 μm or less, 3.0 μm or less, 2.5 μm or less, 2.0 μm or less, 1.5 μm or less, 1.2 μm or less, 1.0 μm or less, 0.9 μm or less, 0.8 μm or less, or less than 0.8 μm. When the volume-based cumulative 5% particle size (D5) of the film-forming powder is within the above range, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by erosion of the film can be suppressed. In one embodiment of the present invention, the volume-based cumulative 5% particle size (D5) of the film-forming powder is 0.001 μm or more and 5.0 μm or less, 0.005 μm or more and 3.0 μm or less, 0.01 μm or more and 2.0 μm or less, 0.001 μm or more and 1.5 μm or less, 0.005 μm or more and 1.5 μm or less, or 0.01 μm or more and 1.5 μm or less.

[0029] (Volume-based cumulative 10% particle size (D10) of film-forming powder) In one embodiment of the present invention, the volume-based cumulative 10% particle size (D10) of the film-forming powder is 0.005 μm or more, 0.01 μm or more, 0.02 μm or more, 0.03 μm or more, 0.04 μm or more, 0.05 μm or more, 0.08 μm or more, 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, or 0.6 μm or more. When the volume-based cumulative 10% particle size (D10) of the film-forming powder is within the above range, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by erosion of the film can be suppressed.

[0030] In one embodiment of the present invention, the volume-based cumulative 10% particle size (D10) of the film-forming powder is 8.0 μm or less, 7.0 μm or less, 6.0 μm or less, 5.0 μm or less, 4.5 μm or less, 4.0 μm or less, 3.0 μm or less, 2.5 μm or less, 2.0 μm or less, 1.5 μm or less, 1.2 μm or less, 1.0 μm or less, 0.9 μm or less, or less than 0.9 μm. When the volume-based cumulative 10% particle size (D10) of the film-forming powder is within the above range, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by erosion of the film can be suppressed. In one embodiment of the present invention, the volume-based cumulative 10% particle size (D10) of the film-forming powder is 0.5 μm or more and 5.0 μm or less.

[0031] (Volume-based cumulative 90% particle size (D90) of film-forming powder) In one embodiment of the present invention, the volume-based cumulative 90% particle size (D90) of the film-forming powder is 0.1 μm or more, 0.2 μm or more, 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, 0.9 μm or more, 1.0 μm or more, 1.5 μm or more, 2.0 μm or more, 2.5 μm or more, or greater than 2.5 μm. When the volume-based cumulative 90% particle size (D90) of the film-forming powder is within the above range, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by erosion of the film can be suppressed.

[0032] In one embodiment of the present invention, the volume-based cumulative 90% particle size (D90) of the film-forming powder is 15 μm or less, 12 μm or less, 11 μm or less, 10 μm or less, 9.5 μm or less, 9.0 μm or less, 8.5 μm or less, 8.0 μm or less, 7.5 μm or less, 7.0 μm or less, 6.0 μm or less, 5.5 μm or less, 5.0 μm or less, 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, or 2.8 μm or less. When the volume-based cumulative 90% particle size (D90) of the film-forming powder is within the above range, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by erosion of the film can be suppressed. In one embodiment of the present invention, the volume-based cumulative 90% particle size (D90) of the film-forming powder is 0.1 μm or more and 15 μm or less, 0.1 μm or more and 10 μm or less, 0.1 μm or more and 8.5 μm or less, 0.1 μm or more and 5.0 μm or less, or 0.1 μm or more and 3.0 μm or less.

[0033] (Volume-based cumulative 95% particle size (D95) of film-forming powder) In one embodiment of the present invention, the volume-based cumulative 95% particle size (D95) of the film-forming powder is 0.3 μm or more, 0.4 μm or more, 0.5 μm or more, 0.6 μm or more, 0.7 μm or more, 0.8 μm or more, 0.9 μm or more, 1.0 μm or more, 1.5 μm or more, 2.0 μm or more, 2.5 μm or more, 3.0 μm or more, or greater than 3.0 μm. When the volume-based cumulative 95% particle size (D95) of the film-forming powder is within the above range, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by erosion of the film can be suppressed.

[0034] In one embodiment of the present invention, the volume-based cumulative 95% particle size (D95) of the film-forming powder is 18 μm or less, 15 μm or less, 12 μm or less, 11 μm or less, 10 μm or less, 9.5 μm or less, 9.0 μm or less, 8.5 μm or less, 8.0 μm or less, 7.5 μm or less, 7.0 μm or less, 6.0 μm or less, 5.5 μm or less, 5.0 μm or less, 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, or less than 3.5 μm. In one embodiment of the present invention, the volume-based cumulative 95% particle size (D95) of the film-forming powder is 0.3 μm to 18 μm, 0.3 μm to 15 μm, 0.3 μm to 10 μm, 0.3 μm to 8.0 μm, 0.1 μm to 7.0 μm, or 0.1 μm to 5.0 μm. When the volume-based cumulative 95% particle size (D95) of the film-forming powder is within the above range, the effect of improving the density of the formed film is more pronounced. As a result, a dense film can be formed, and consequently, particles generated by erosion of the film can be suppressed.

[0035] (Span Value) In one embodiment of the present invention, the span value of the film-forming powder is 1.55 or less. The span value is a value calculated by the formula {particle diameter (D90) μm - particle diameter (D10) μm} / particle diameter (D50) μm. In this specification, when the span value is simply referred to, it is the span value between particle diameter D90 and particle diameter D10. As described above, since the 50% particle diameter (D50) of the film-forming powder disclosed herein is small, the density of the film formed using it is improved, and the erosion resistance is improved. Furthermore, by making the span value of the film-forming powder small, to 1.55 or less, there is no large difference in particle diameter, the film-forming powder is easier to melt and disperse, and the density of the film obtained using the film-forming powder is further improved. As a result, a highly dense film can be formed, and consequently, particles generated by erosion of the film can be suppressed.

[0036] In one embodiment of the present invention, the span value of the film-forming powder is 1.50 or less, 1.45 or less, 1.40 or less, 1.35 or less, or 1.30 or less. By having a moderately small span value for the film-forming powder, the density of the film can be further improved. In another embodiment of the present invention, the span value of the film-forming powder is 0.50 or more, 0.55 or more, 0.60 or more, 0.70 or more, 0.80 or more, 0.90 or more, 0.95 or more, 1.00 or more, 1.10 or more, 1.20 or more, or greater than 1.20. By appropriately adjusting the lower limit of the span value of the film-forming powder, the density of the film can be further improved.

[0037] (D95-D5) The value between the particle diameter D95 and particle diameter D5 of the film-forming powder (hereinafter referred to as "D95-D5") is calculated by the formula: particle diameter (D95) - particle diameter (D5). In one embodiment of the present invention, D95-D5 is less than 10 μm, 9.0 μm or less, 8.0 μm or less, 7.0 μm or less, 6.0 μm or less, 5.0 μm or less, 4.5 μm or less, 4.0 μm or less, 3.5 μm or less, 3.0 μm or less, 2.5 μm or less, or less than 2.5 μm. The density of the film can be further improved by appropriately adjusting the upper limit of D95-D5 of the film-forming powder.

[0038] In one embodiment of the present invention, the D95-D5 of the film-forming powder is 0.1 μm or more, 0.5 μm or more, 1.0 μm or more, 1.2 μm or more, 1.5 μm or more, 1.8 μm or more, 2.0 μm or more, or 2.2 μm or more. By appropriately adjusting the lower limit of the D95-D5 of the film-forming powder, the density of the film can be further improved.

[0039] ((D95-D5) / D50) In one embodiment of the present invention, the film-forming powder also has a significant characteristic in the value obtained by dividing the difference between particle diameter D95 and particle diameter D5 by particle diameter D50. The value obtained by dividing the difference between particle diameter D95 and particle diameter D5 by particle diameter D50 (hereinafter, "(D95-D5) / D50") is a value calculated by the formula {particle diameter (D95) μm - particle diameter (D5) μm} / particle diameter (D50) μm. The (D95-D5) / D50 of the film-forming powder is 2.50 or less, 2.30 or less, 2.20 or less, 2.10 or less, 2.00 or less, 1.90 or less, 1.80 or less, 1.70 or less, or 1.60 or less. The density of the film can be further improved by appropriately adjusting the upper limit of (D95-D5) / D50 of the film-forming powder.

[0040] In one embodiment of the present invention, the (D95-D5) / D50 of the film-forming powder is 0.10 or more, 0.50 or more, 0.80 or more, 1.00 or more, 1.10 or more, 1.20 or more, 1.30 or more, 1.40 or more, 1.50 or more, or greater than 1.50. The density of the film can be further improved by appropriately adjusting the lower limit of the (D95-D5) / D50 of the film-forming powder.

[0041] (Content of particles with a particle diameter of less than 20 μm) In one embodiment of the present invention, the content of particles with a particle diameter of less than 20 μm in the film-forming powder is 95.0% by mass or more, 99.0% by mass or more, 99.5% by mass or more, 99.7% by mass or more, 99.8% by mass or more, 99.9% by mass or more, 99.95% by mass or more, 99.99% by mass or more, or greater than 99.99% by mass. In one embodiment of the present invention, the content of particles with a particle diameter of less than 20 μm in the film-forming powder may be 100% by mass, or less than 100% by mass (for example, 99.99% by mass or less, or 99.98% by mass or less). The density of the film can be further improved by having the content of particles with a particle diameter of less than 20 μm in the film-forming powder within the above range. The content of particles with a particle diameter of less than 20 μm in the film-forming powder can be determined by the method described in the examples.

[0042] (Content of particles with a particle size of less than 15 μm) In one embodiment of the present invention, the content of particles with a particle size of less than 15 μm in the film-forming powder is 95.0% by mass or more, 99.0% by mass or more, 99.5% by mass or more, 99.7% by mass or more, 99.8% by mass or more, 99.9% by mass or more, 99.95% by mass or more, 99.99% by mass or more, or greater than 99.99% by mass. In one embodiment of the present invention, the content of particles with a particle size of less than 15 μm in the film-forming powder may be 100% by mass, or less than 100% by mass (for example, 99.99% by mass or less, or 99.98% by mass or less). The density of the film can be further improved by having the content of particles with a particle size of less than 15 μm in the film-forming powder within the above range. The content of particles with a particle size of less than 15 μm in the film-forming powder can be determined by the method described in the examples.

[0043] (Content of particles with a particle diameter of less than 10 μm) In one embodiment of the present invention, the content of particles with a particle diameter of less than 10 μm in the film-forming powder is 90.0% by mass or more, 92.0% by mass or more, 95.0% by mass or more, 99.0% by mass or more, 99.5% by mass or more, 99.7% by mass or more, 99.8% by mass or more, 99.9% by mass or more, 99.95% by mass or more, 99.99% by mass or more, or more than 99.99% by mass. That is, the content of particles with a particle diameter of 10 μm or more is 10.0% by mass or less, 8.0% by mass or less, 5.0% by mass or less, 1.0% by mass or less, 0.5% by mass or less, 0.3% by mass or less, 0.2% by mass or less, 0.1% by mass or less, 0.05% by mass or less, or 0.01% by mass or less. In one embodiment of the present invention, the content of particles with a particle size of less than 10 μm in the film-forming powder may be 100% by mass, or less than 100% by mass (for example, 99.99% by mass or less, or 99.98% by mass or less). By having the content of particles with a particle size of less than 10 μm in the film-forming powder within the above range, the density of the film can be further improved. The content of particles with a particle size of less than 10 μm in the film-forming powder can be determined by the method described in the examples.

[0044] (Content of particles with a particle size of less than 5 μm) In one embodiment of the present invention, the content of particles with a particle size of less than 5 μm in the film-forming powder is 85.0% by mass or more, 90.0% by mass or more, 92.0% by mass or more, 95.0% by mass or more, 99.0% by mass or more, 99.5% by mass or more, 99.7% by mass or more, 99.8% by mass or more, 99.9% by mass or more, or more than 99.9% by mass. In one embodiment of the present invention, the content of particles with a particle size of less than 10 μm in the film-forming powder may be 100% by mass, or less than 100% by mass (for example, 99.99% by mass or less, or 99.98% by mass or less). The density of the film can be further improved by having the content of particles with a particle size of less than 5 μm in the film-forming powder within the above range. The content of particles with a particle size of less than 5 μm in the film-forming powder can be determined by the method described in the examples.

[0045] According to one embodiment of the present invention, the film-forming powder is not a granulated powder. A granulated powder refers to a powder (for example, oxide ceramics) in which primary particles are integrated into the form of secondary particles. Granulated powder also includes, for example, processing a powdery substance into granules. In other words, the film-forming powder is not a granule. A film-forming powder can be determined to be not a granulated powder if, for example, it is a powder that is not in the form of secondary particles, or a powder that has no voids in the particles. Hereinafter, film-forming powder that is not a granulated powder will also be referred to as "dense powder". According to one embodiment, film-forming powder that is not a granulated powder (dense powder) does not contain a binder such as a binder, and consists of a single oxide or a complex oxide. Here, "consisting of a single oxide or a complex oxide" means that it may contain substances that are inevitably included. The content of the inevitably included substances is, for example, 0.5% by mass or less, 0.2% by mass or less, 0.1% by mass or less, 0.05% by mass or less, or 0.01% by mass or less, relative to the total mass of the film-forming powder. According to one embodiment, the single compound may be an oxide-based ceramic (preferably a single oxide or a composite oxide). According to one embodiment, the film-forming powder (dense powder) that is not a granulated powder (for example, a film-forming powder consisting of a single oxide or a composite oxide) has a D50 of 5.0 μm or less.

[0046] According to one embodiment, the film-forming powder (dense powder) that is not granulated powder (for example, film-forming powder consisting of a single oxide or a composite oxide) has a cross-sectional porosity of 1.0% to 6.0%, 1.5% to 6.0%, 2.0% to 6.0%, 1.5% to 5.5%, 2.0% to 5.5%, or 2.0% to 5.0%. According to one embodiment, the dense powder (for example, film-forming powder consisting of a single oxide or a composite oxide) has a D50 of 5.0 μm or less and a cross-sectional porosity of 1.0% to 6.0%. According to one embodiment, the film-forming powder is dense powder and has a cross-sectional porosity of 1.0% to 6.0%, 1.5% to 6.0%, 2.0% to 6.0%, 1.5% to 5.5%, 2.0% to 5.5%, or 2.0% to 5.0%. The cross-sectional porosity of the film-forming powder is determined by the method described in the examples.

[0047] According to one embodiment of the present invention, the film-forming powder is a granulated powder. Granulated powder, as described above, means a powder in which primary particles, for example, primary particles of oxide-based ceramics (preferably single oxides or composite oxides), are integrated into the form of secondary particles. According to one embodiment, the granulated powder has a cross-sectional porosity of 10% to 30%, 15% to 27%, or 18% to 24%. According to one embodiment, the granulated powder may be granulated sintered powder (also called granulated calcined powder). Granulated sintered powder is obtained by calcining the above-mentioned granulated powder. According to one embodiment, the film-forming powder is granulated sintered powder with a cross-sectional porosity of 10% to 30%, 15% to 27%, or 18% to 24%. The granulated powder (granulated sintered powder) may contain optional components added as needed (e.g., binders, various additives (e.g., dispersants)). Granulated powder (granulated sintered powder) can be used by any of the following methods: thermal spraying, aerosol deposition (AD), CVD, PVD, etc., but it is preferably used in thermal spraying (for example, atmospheric pressure plasma spraying, suspension plasma (SPS)).

[0048] In granulated sintered powder, primary particles of oxide ceramics (preferably single oxides or composite oxides) are integrated by firing. This bonding is achieved, for example, by firing at least a portion of the primary particles of oxide ceramics. As a result, in granulated sintered powder, the primary particles are more strongly bonded to each other by firing, making the secondary particles less likely to break during the thermal spraying process. This allows the film-forming powder obtained by thermal spraying to form a more densely packed film.

[0049] According to one embodiment, the film-forming powder is at least one of a dense powder and a granulated sintered powder.

[0050] 《Method for Producing Film-Forming Powder》 First, a preferred embodiment of the method for producing film-forming powder disclosed herein will be outlined. Although not limited thereto, a metal compound that will be used as a raw material for ceramics is mixed with water to prepare an aqueous solution containing the metal compound that will be used as a raw material for ceramics. Next, the aqueous solution containing the metal compound is mixed with an acidic aqueous solution to precipitate a ceramic precursor. The ceramic precursor thus obtained is calcined to obtain a calcined body, which is then further crushed and classified to produce film-forming powder.

[0051] [Preparation Process for Aqueous Solutions Containing Metal Compounds] As a method for preparing the powder for film formation, first, an aqueous solution containing a metal compound that will be used as a raw material for ceramics is prepared. Examples of metal compounds that will be used as raw materials for ceramics include metal nitrates, sulfates, hydroxides, carbonates, phosphates, chlorides, borides, fluorides, etc. Examples of metals in the metal compounds include the metal elements mentioned above. For example, one or more selected from lanthanide rare earth elements such as La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; and scandium rare earth elements such as Sc and Y. Two or more metal compounds may be used, and therefore, an aqueous solution containing two or more metal compounds may be used.

[0052] The aqueous solution containing the metal compound preferably has a concentration of the metal compound of 0.01 mol / L or more and 1.0 mol / L or less, more preferably 0.02 mol / L or more and 0.8 mol / L or less, and even more preferably 0.03 mol / L or more and 0.5 mol / L or less.

[0053] [Preparation step for ceramic precursor] The preparation step for ceramic precursor includes thoroughly stirring an aqueous solution containing a metal compound and then mixing it with an acidic aqueous solution such as oxalic acid to precipitate the ceramic precursor. Here, the method of mixing the aqueous solution containing the metal compound and the acidic aqueous solution is to add the acidic aqueous solution to the aqueous solution containing the metal compound, to add the aqueous solution containing the metal compound to the acidic aqueous solution, or to add the aqueous solution containing the metal compound and the acidic aqueous solution simultaneously to a single container. From the viewpoint of obtaining a film-forming powder having a large specific surface area and a small volume-based cumulative 50% particle size, it is preferable to add the acidic aqueous solution to the aqueous solution containing the metal compound.

[0054] According to one embodiment, the addition of an acidic aqueous solution to an aqueous solution containing a metal compound may be performed dropwise. For example, an acidic aqueous solution is added dropwise to an aqueous solution containing a metal compound. When the acidic aqueous solution is added dropwise, the dropping rate is preferably 0.5 mL / min or more, more preferably 0.8 mL / min or more, even more preferably 1.0 mL / min or more, particularly preferably 1.2 mL / min or more, and most preferably 1.5 mL / min or more. Alternatively, when the acidic aqueous solution is added dropwise, the dropping rate is preferably 50 mL / min or less, more preferably 35 mL / min or less, even more preferably 30 mL / min or less, particularly preferably 25 mL / min or less, and most preferably 20 mL / min or less. That is, when an acidic aqueous solution is added dropwise, the dropping rate is preferably 0.5 mL / min or more and 50 mL / min or less, more preferably 0.8 mL / min or more and 35 mL / min or less, even more preferably 1.0 mL / min or more and 30 mL / min or less, particularly preferably 1.2 mL / min or more and 25 mL / min or less, and most preferably 11.5 mL / min or more and 20 mL / min or less. According to one embodiment, when an acidic aqueous solution is added dropwise, the dropping rate is 1 mL / min or more and 40 mL / min or less, 1 mL / min or more and 30 mL / min or less, 1 mL / min or more and 20 mL / min or less, 1 mL / min or more and 15 mL / min or less, 1 mL / min or more and 12 mL / min or less, 1 mL / min or more and 10 mL / min or less, or 1 mL / min or more and 5 mL / min or less. If the dropping rate of the acidic aqueous solution is within the above range when it is added dropwise, the resulting film-forming powder can form a film with even greater density.

[0055] According to one embodiment, the method for producing a film-forming powder according to this embodiment includes a step of precipitating a ceramic precursor by dropping an acidic aqueous solution into an aqueous solution containing a metal compound and mixing the two solutions.

[0056] As for the acidic aqueous solution, it is preferable that the concentration of the acidic substance (oxalic acid in the case of an oxalic acid aqueous solution) is 0.01 mol / L or more and 1.0 mol / L or less, more preferably 0.02 mol / L or more and 0.8 mol / L or less, and even more preferably 0.03 mol / L or more and 0.5 mol / L or less.

[0057] In the preparation process of the ceramic precursor, the molar ratio of the metal compound to the acidic substance (moles of metal compound:moles of acidic substance) is preferably 10:90 to 80:20, more preferably 20:80 to 70:30, and even more preferably 30:70 to 60:40. If the molar ratio of the metal compound to the acidic substance is within the above range, the resulting film-forming powder can form a film with even greater density.

[0058] In the preparation step of the ceramic precursor, the mixing temperature of the aqueous solution containing the metal compound and the acidic aqueous solution is preferably 10°C to 50°C, more preferably 15°C to 45°C, even more preferably 20°C to 40°C, and particularly preferably 20°C to 35°C. By mixing within the above range, the resulting film-forming powder can form a film with even greater density.

[0059] In the preparation process of the ceramic precursor, the ceramic precursor precipitates when an aqueous solution containing a metal compound and an acidic aqueous solution are stirred. The ceramic precursor can be obtained as a solid by solid-liquid separation such as suction filtration. It is preferable to wash the ceramic precursor obtained by solid-liquid separation with water or the like.

[0060] [Firing Process] The precipitated ceramic precursor is dried and then fired to produce a fired body. In one embodiment of the present invention, the firing temperature of the ceramic precursor is 300°C or higher, 400°C or higher, 500°C or higher, or 600°C or higher. In one embodiment of the present invention, the firing temperature of the ceramic precursor is 1500°C or lower, 1300°C or lower, 1200°C or lower, or 1000°C or lower. In one embodiment of the present invention, the firing temperature of the ceramic precursor is 300°C or higher and 1500°C or lower, 400°C or higher and 1300°C or lower, 500°C or higher and 1200°C or lower, or 600°C or higher and 1000°C or lower. In one embodiment of the present invention, the firing time of the ceramic precursor may be 1 hour or more, 2 hours or more, or 4 hours or more. In one embodiment of the present invention, the firing time of the ceramic precursor is usually 24 hours or less. In one embodiment of the present invention, the firing time of the ceramic precursor is 1 hour or more and 24 hours or less. The firing of the ceramic precursor is preferably carried out in an atmospheric environment.

[0061] [Crushing step] After firing the ceramic precursor, a crushing step may be included in which the fired body is crushed. The crushing step is, for example, a step of crushing the fired body. The fired body can be crushed by, for example, a pulverizer. Examples of pulverizers that can be used include jaw crushers, cone crushers, hammer crushers, roll crushers, millstone crushers, etc. The degree of crushing of the fired body can be appropriately set, for example, so that the resulting film-forming powder is likely to have a desired particle size distribution.

[0062] [Classification Process] The calcined body may include a classification process for classifying the crushed calcined body. The classification process is, for example, a process for classifying the particles obtained in the crushing process. This allows the particle size distribution to be adjusted to a desired level. For the classification process, in addition to classification by sieving, classifiers such as an airflow classifier utilizing the Coanda effect (e.g., MDS-3 manufactured by Nippon Pneumatic Mfg. Co., Ltd.), a swirling airflow classifier, a forced vortex centrifugal classifier, and a semi-free vortex centrifugal classifier may be used. In one embodiment of the present invention, the crushed calcined body may be classified such that the volume-based cumulative 50% particle size (D50) of the resulting film-forming powder is less than 10 μm.

[0063] It is preferable to produce the film-forming powder in the manner described above. The film-forming powder obtained here is not a granulated powder, but a film-forming powder consisting of a single oxide or a composite oxide.

[0064] After firing, the resulting film-forming powder has a specific surface area of ​​2.5 m². ２ The particle size is 2.5 m² or more, and the volume-based cumulative 50% particle size is less than 10 μm. Furthermore, the specific surface area of ​​the above film-forming powder is determined by the precipitation of ceramic precursors from aqueous solutions containing metal compounds (concentration of metal compounds, aqueous solution temperature, solvent, etc.); pulverization of ceramic precursors after firing; classification, etc., ensuring the film-forming powder has the desired configuration (i.e., a specific surface area of ​​2.5 m²). ２ This can be prepared by selecting a particle size that is 1 / g or more and has a volume-based cumulative 50% particle diameter of less than 10 μm.

[0065] [Method for producing granulated powder] According to one embodiment, as described above, the powder for film formation can be obtained by granulating the powder obtained by firing a ceramic precursor, and this granulated powder can be used as the powder for film formation. Alternatively, the granulated powder (granulated sintered product) obtained by the following method can also be used as the powder for film formation.

[0066] As a method for obtaining granulated powder, for example, one or more metal oxide particles (metal oxide powder) can be mixed with other arbitrary components and compounded as raw material particles (raw material powder) for oxide ceramics. According to one embodiment, the granulated powder is a granulated sintered powder prepared by mixing one or more metal oxide particles (metal oxide powder) with other arbitrary components, compounding them, and then firing them. According to one embodiment, the granulated powder (granulated sintered powder) is a secondary particle formed by mixing one or more raw material particles (primary particles), granulating them, and then firing them, in which each primary particle is three-dimensionally bonded with gaps between them.

[0067] If the film-forming powder disclosed herein is composed of granulated sintered powder, the method for producing the film-forming powder may include, for example, a granulation step, a calcination step, a crushing step, and a classification step.

[0068] The granulation process is, for example, a process of granulating raw material particles. In this process, for example, one or more metal oxide particles are prepared so that a desired composition ratio of oxide ceramics contained in the film-forming powder can be achieved, and their surfaces are stabilized with a protective agent or the like as needed. Next, these stabilized raw material particles are dispersed in a suitable solvent along with a binder as an optional component, various additives (e.g., dispersants) as needed, to prepare a dispersion. Mixers and dispersers such as homogenizers and impeller-type agitators are used to disperse the raw material particles in the solvent. Next, granulated particles are produced using the obtained dispersion by employing a granulation method such as wet granulation.

[0069] Examples of granulation methods include rolling granulation, fluidized bed granulation, agitation granulation, crushing granulation, melt granulation, spray granulation, and microemulsion granulation. Among these, spray granulation is considered a particularly suitable granulation method. In spray granulation, droplets are formed from the dispersion (spray liquid) obtained as described above. Granulated particles are produced when the droplets are carried by an airflow and passed through a spray dryer.

[0070] Furthermore, the concentration of raw material particles in the spray solution is preferably, for example, 10% by mass or more and 80% by mass or less. Examples of binders to be added include polyvinyl butyral resin (PVB), polyvinyl alcohol resin (PVA), polyvinyl acetate resin, polyacrylic resin, polytetrafluoroethylene (PTFE), styrene-butadiene rubber (SBR), polyvinylidene fluoride (PVDF), methylcellulose (CMC), and ethylcellulose. Water can be used as a solvent, for example. The amount of binder added is preferably adjusted to a ratio of more than 0.5% by mass and 10% by mass or less (for example, 1% by mass or more and 5% by mass or less) relative to the mass of the raw material particles.

[0071] The calcination process is, for example, a process of calcining granulated particles. In the calcination process, the granulated particles are calcined for 1 to 10 hours at a predetermined temperature (generally 1000°C to 2000°C) in an air atmosphere; an inert atmosphere such as a nitrogen atmosphere or a noble gas atmosphere; or in a vacuum. This predetermined temperature may be, for example, the set temperature of the calcination furnace. The temperature and time when calcining the granulated particles can be set appropriately to achieve the desired composition of the powder for film formation.

[0072] The crushing step is, for example, a step in which the calcined material obtained in the calcination step is crushed. The calcined material may be crushed by, for example, a pulverizer. Preferably, a jaw crusher, cone crusher, hammer crusher, roll crusher, or millstone pulverizer is used as the pulverizer. The crushing step can produce granulated sintered powder in the form of secondary particles in which primary particles are bonded (calcined) with gaps between them. The degree to which the calcined material is crushed in this step can be appropriately set, for example, to achieve a desired particle size distribution of secondary particles.

[0073] The classification process is, for example, a process in which the secondary particles obtained in the crushing process are classified. This allows the particle size distribution of the secondary particles to be adjusted to a desired level. Classification methods include, for example, sieving, as well as air-flow classifiers utilizing the Coanda effect, swirling air-flow classifiers, forced-vortex centrifugal classifiers, and semi-free-vortex centrifugal classifiers.

[0074] Here, the granulated powder may be a granulated sintered powder prepared by mixing the above-mentioned ceramic precursor with other optional components, compounding them, and then firing them. Alternatively, the granulated powder may be a granulated sintered powder prepared by mixing oxide-based ceramics obtained by firing the above-mentioned ceramic precursor with other optional components and then compounding them. The granulated powder may be a granulated sintered powder prepared by mixing oxide-based ceramics obtained by firing the above-mentioned ceramic precursor with other optional components, compounding them, and then firing them. The other optional components, mixing, and firing conditions are the same as those for the granulation process, firing process, crushing process, and classification process described above.

[0075] The film-forming powder may also consist of molten and ground oxide ceramics in other forms. In the production of molten and ground powder, for example, first, the above-mentioned ceramic precursor or metal oxide particles are prepared as raw materials. Next, the above-mentioned ceramic precursor or metal oxide particles are heated and melted in an electric furnace or the like to obtain a molten mixture of the ceramic precursor or metal oxide particles. Next, the molten mixture of the ceramic precursor or metal oxide particles is rapidly cooled and solidified to obtain a solidified product. Then, the solidified product is crushed and classified to produce molten and ground oxide ceramics powder for film formation. By making the film-forming powder from molten and ground oxide ceramics powder, the film-forming powder can be obtained more easily.

[0076] 《Uses of Film-Forming Powders》 The film-forming powders disclosed herein are preferably used to form films. According to another aspect of the present invention, a film formed using the above-mentioned film-forming powders is provided. Furthermore, according to another aspect of the present invention, a method for producing a film is provided, which includes forming a film using the above-mentioned film-forming powders.

[0077] Methods for forming a film using the film-forming powders disclosed herein include thermal spraying, aerosol deposition (AD) method, CVD method, and PVD method. The film-forming powders disclosed herein are preferably formed by thermal spraying or aerosol deposition, and more preferably by thermal spraying. When forming a film using thermal spraying or aerosol deposition, the film-forming powders disclosed herein can form a denser film.

[0078] The film-forming powder disclosed herein can be used to produce sprayed coatings on various substrates by spraying it using various thermal spraying methods. The film-forming powder can be particularly preferably used to produce sprayed coatings by plasma spraying methods such as atmospheric pressure plasma spraying (APS), low pressure plasma spraying (LPS), high pressure plasma spraying (high pressure plasma spraying), and suspension plasma spraying (SPS). Furthermore, the film-forming 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 film-forming powder may be supplied to the spraying apparatus in powder form, or in slurry form dispersed in a suitable dispersion medium.

[0079] In this embodiment, the film-forming powder is very preferably a slurry obtained by mixing and dispersing the film-forming powder in a dispersion medium. The dispersion medium is not particularly limited as long as it can disperse the film-forming powder, but examples include deionized water, alcohol solution, and a mixture of deionized water and alcohol solution.

[0080] The content of film-forming powder in the slurry, i.e., the solid content concentration, is preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more. For example, when used as a thermal spray slurry, it becomes easier to improve the thickness of the thermal spray coating produced per unit time from the slurry, i.e., the thermal spray efficiency.

[0081] The content of the film-forming powder in the slurry is preferably 70% by mass or less (less than 70% by mass), more preferably 60% by mass or less, and even more preferably 50% by mass or less. For example, when used as a thermal spray slurry, it becomes easy to obtain a thermal spray slurry with the required fluidity suitable for good supply to a thermal spray apparatus, that is, a thermal spray slurry with the required fluidity sufficient for the formation of a thermal spray coating.

[0082] The slurry described above may contain various additives in addition to the film-forming powder in the dispersion medium. For example, dispersants (anionic surfactants, cationic surfactants, nonionic surfactants, etc.) may be mixed in.

[0083] Therefore, according to the present invention, a thermal spray slurry containing the above-mentioned film-forming powder and a dispersion medium is also provided.

[0084] By atomizing the film-forming powder disclosed herein, mixing it with a gas such as helium, nitrogen, or oxygen to form an aerosol, and spraying it onto a substrate through a nozzle in a reduced-pressure atmosphere, aerosol deposition films can be produced on various substrates. The aerosol deposition method includes the plasma AD method.

[0085] Therefore, according to one embodiment, the film formed by the film-forming powder disclosed herein may be a thermal spray film or an aerosol deposition film. Furthermore, according to one embodiment, a method for manufacturing a film is provided, in which the above-mentioned film-forming slurry is formed by thermal spraying or aerosol deposition.

[0086] The type of substrate used to produce a thermal spray coating or aerosol deposition 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 useful as lightweight structural materials, and corrosion-resistant alloys of Ni, Co, and Fe groups such as Hastelloy®, Inconel®, Stellite®, and Invar.

[0087] 《Films formed from film-forming powders》 (Film porosity) Films formed using the film-forming powders disclosed herein have high density. For example, the film porosity of films formed using the film-forming powders disclosed herein is 3.0% or less. Film porosity is the porosity of a film formed using the film-forming powders, and is specifically calculated by the measurement method described in the examples. The low film porosity of films formed using the film-forming powders disclosed herein means that the formed film has high density. This improves the erosion resistance of the film and suppresses particle generation. In order to make the film porosity 3.0% or less, as described above, it is preferable to adjust the preparation conditions of the film-forming powders so that they have a large specific surface area and a small volume-based cumulative 50% particle size.

[0088] According to one embodiment of the present invention, the porosity of a film formed by the film-forming powder is 2.9% or less, 2.8% or less, 2.7% or less, 2.6% or less, 2.5% or less, 2.4% or less, 2.3% or less, 2.2% or less, or less than 2.2%. By making the porosity of the film formed by the film-forming powder even smaller, the pores in the film become fewer and denser, improving the erosion resistance of the film and further suppressing particle generation. According to one embodiment of the present invention, the porosity of a film formed by the film-forming powder is, for example, 1.0% or more, 1.2% or more, 1.5% or more, 1.6% or more, or 1.8% or more. According to one embodiment of the present invention, the porosity of a film formed by the film-forming powder is 1.0% or more and 3.0% or less, or 1.0% or more and 2.5% or less.

[0089] While embodiments of the present invention have been described in detail, these are descriptive and illustrative, and not limiting, and it is clear that the scope of the present invention should be interpreted by the appended claims.

[0090] The present invention encompasses the following embodiments and forms: [1] with a specific surface area of ​​2.5 m² ２ [1] A film-forming material having a particle size of 1 / g or more and a volume-based cumulative 50% particle size (D50) of less than 10 μm; [2] A film-forming powder according to [1] above, containing rare earth elements; [3] A film-forming powder according to [1] or [2] above, having a span value (D90-D10) / D50 in the volume-based particle size distribution of 1.55 or less; [4] A specific surface area of ​​5.0 m² ２ A film-forming powder according to any of [1] to [3] above, having a specific surface area of ​​5.0 m² or more; [5] a specific surface area of ​​5.0 m² ２ / g or more 10.0m ２ A film-forming powder according to any of [1] to [4] above, having a specific surface area of ​​5.0 m² or less; [6] a specific surface area of ​​5.0 m² ２ / g or more 10.0m ２[1] to [5] above, wherein the amount is less than or equal to / g and the volume-based cumulative 50% particle size (D50) is 2.5 μm or less; [7] The film-forming powder according to any one of [1] to [6] above, wherein the span value (D90-D10) / D50 in the volume-based particle size distribution is 1.30 or less; [8] The film-forming powder according to any one of [1] to [7] above, wherein the content of particles with a particle size of less than 5 μm is 85% by mass or more; [9] The film-forming powder according to any one of [1] to [8] above, wherein the content of particles with a particle size of 10 μm or more is 0.5% by mass or less;

[10] The film-forming powder according to any one of [1] to [9] above, which is a monooxide consisting of an oxide of a single metal element;

[11] The film-forming powder according to any one of [1] to [9] above, which is at least one of granulated sintered powder and dense powder.

[12] A film formed using the film-forming powder described in any of [1] to

[11] above;

[13] A slurry comprising the film-forming powder described in any of [1] to

[11] above and a dispersion medium;

[0091] The present invention will be described in more detail using the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Unless otherwise specified, "%" and "parts" mean "mass percent" and "parts by mass," respectively. In addition, in the following examples, unless otherwise specified, the operations were carried out under conditions of room temperature (25°C) / relative humidity of 40% RH to 50% RH.

[0092] 《Preparation of Film-Forming Powder》 [Comparative Example 1] 10 kg of an aqueous solution of ammonium bicarbonate (25°C) containing 13.0% by mass of ammonium bicarbonate was prepared, along with 40 L of an aqueous solution of yttrium nitrate (25°C) with a concentration of 300 g / L in terms of oxide equivalent. The aqueous solution of yttrium nitrate was added at a rate of 100 mL / min, and the aqueous solution of ammonium bicarbonate was added to the same reaction bed at a flow rate such that the pH of the mixture of both solutions became 6.8. The mixture in the container was stirred at 20,000 rpm at the time of addition. The suspension that overflowed from the container was filtered sequentially for 20 seconds, then the addition of both solutions and stirring were stopped, and the filtered residue was washed with 10 L of ethanol. This washing of the residue was repeated 5 times. The time taken from the start of mixing of the two solutions to the start of filtration was 60 to 120 seconds. The residue after washing was calcined at 600°C in an atmospheric environment to obtain the film-forming powder Y of Comparative Example 1. ２ O ３ (Approximately 10 g) was obtained. The volume of the reaction vessel was 100 ml. ２ O ３ The yield was approximately 99%, calculated from a 20-second filtration period.

[0093] [Example 1] 750 mL of 1 mol / L oxalic acid aqueous solution (25°C) and 500 mL of 1 mol / L yttrium nitrate aqueous solution (25°C) were prepared. The yttrium nitrate solution was stirred in a container at 500 rpm, and the oxalic acid aqueous solution was added at a rate of 10 mL / min and mixed. Stirring was continued for 10 to 15 minutes to obtain a suspension. The residue was recovered from the obtained suspension by suction filtration. To recover the residue in the container, the container was washed five times with distilled water and then rinsed with water. The residue after washing was calcined at 800°C for 4 hours under an atmospheric atmosphere to obtain 10 to 15 g of the film-forming powder Y of Example 1. ２ O ３ (10-15g) was obtained. Y at this time ２ O ３ The yield was over 98% of the calculated yield.

[0094] [Example 2] The same procedure as in Example 1 was followed, except that 500 mL of 1 mol / L yttrium nitrate aqueous solution (25°C) was replaced with 500 mL of 1 mol / L ytterbium nitrate aqueous solution (25°C), to obtain the film-forming powder Yb of Example 2. ２ O ３ (10-15 g) was obtained. Yb at this time ２ O ３ The yield was over 98% of the calculated yield.

[0095] [Example 3] The same procedure as in Example 1 was followed, except that 500 mL of 1 mol / L yttrium nitrate aqueous solution (25°C) was replaced with 500 mL of 1 mol / L gadolinium nitrate aqueous solution (25°C), to obtain the film-forming powder Gd of Example 3. ２ O ３ (10-15 g) was obtained. Gb at this time ２ O ３ The yield was over 98% of the calculated yield.

[0096] [Example 4] The same procedure as in Example 1 was followed except that the dropping rate of the oxalic acid aqueous solution was changed to 2 mL / min, and the film-forming powder Y of Example 4 was used. ２ O ３ (10-15 g) was obtained. After repeating each procedure to secure a sufficient quantity, classification was performed using the MDS-3 manufactured by Nippon Pneumatic Mfg. Co., Ltd. At this time, Y ２ O ３ The yield was more than 50% of the calculated yield.

[0097] [Example 5] The same procedure as in Example 1 was followed except that the dropping rate of the oxalic acid aqueous solution was changed to 2 mL / min, and the film-forming powder Y of Example 5 was used. ２ O ３ (10-15g) was obtained. Y at this time ２ O ３ The yield was over 98% of the calculated yield.

[0098] [Example 6] The same procedure as in Example 1 was followed except that the dropping rate of the oxalic acid aqueous solution was changed to 12 mL / min, and the film-forming powder Y of Example 6 was used. ２ O ３(10-15g) was obtained. Y at this time ２ O ３ The yield was over 98% of the calculated yield.

[0099] [Example 7] As raw material powder, average particle size D ５０ A slurry was prepared by dispersing 1 μm yttrium oxide powder (primary particles) in an aqueous solution containing 2% by mass of a binder (PVA). This slurry was sprayed into an airflow using a spray granulator and dried to produce granulated particles (secondary particles). The obtained granulated particles were subjected to a calcination treatment at 1400°C for 6 hours in an air atmosphere to calcine the primary particles and produce a calcined product. The obtained calcined product was crushed. Subsequently, by performing sieving classification and airflow classification, a film-forming powder Y was obtained, consisting of granulated sintered particles (secondary particles) with uniform particle size. ２ O ３ I obtained it.

[0100] [Example 8] The same procedure as in Example 7 was followed, except that the sieving classification and airflow classification conditions were adjusted so that the result would be D50 as shown in Table 1, to obtain the film-forming powder Y of Example 8. ２ O ３ (10-15 g) was obtained.

[0101] [Methods for measuring various physical properties] In this embodiment, various physical properties were measured by the following methods.

[0102] [Particle Size Distribution (Particle Size)] D5, D10, D50, D90, and D95 ​​refer to the particle size at which the cumulative particle volume from the smallest particle size side reaches 5%, 10%, 50%, 90%, and 95% of the total particle volume, respectively, in the volume-based cumulative particle size distribution. D5, D10, D50, D90, and D95 ​​can be measured by laser diffraction / scattering, and the volume-based particle size distribution was measured using a laser diffraction particle size analyzer (Mastersizer 3000, manufactured by Malvern Panalogical). D50 corresponds to the particle size at 50% cumulative volume.

[0103] Furthermore, the values ​​"-20 μm", "-15 μm", "-10 μm", and "-5 μm" in Table 1 represent the ratios of particles less than 20 μm, less than 15 μm, less than 10 μm, and less than 5 μm relative to the total particle volume of the film-forming powder, as measured using the same device.

[0104] 《Specific Surface Area》 The specific surface area (SA) of the film-forming powder was calculated using the BET method in accordance with the provisions of JIS Z 8830:2013 (ISO 9277:2010) "Method for measuring the specific surface area of ​​powders (solids) by gas adsorption" using a surface area measuring device manufactured by Mountec Co., Ltd., product name "Fully Automatic Specific Surface Area Measuring Device Macorb". Specifically, the specific surface area of ​​the film-forming powder was calculated by determining the amount of gas adsorbed in the monolayer based on the BET method from the adsorption isotherm obtained by the gas adsorption method, and then calculating the specific surface area (SA) based on the molecular size of the adsorbed gas.

[0105] 《Cross-sectional porosity》 Small pieces were prepared by mixing each of the thermal spray powders obtained in the examples and comparative examples with an epoxy resin-based chemical reaction adhesive and solidifying them. The surface of the small pieces was smoothed using JEOL's Handy Wrap (HLA-2), and the cross-section was prepared using JEOL's CROSS SECTION POLISHER (model number: IB-19530CP). Subsequently, the cross-section was observed using an SEM (scanning electron microscope), and the cross-sectional porosity of each film-forming powder was calculated using the images obtained from the SEM observation. Specifically, images were taken using a Thermo Fisher Scientific desktop scanning electron microscope (model number: Phenom Prox) to obtain SEM observation images of the particles of the film-forming powder. The obtained SEM observation images were analyzed using image analysis software included with a Keyence microscope (model number: VHX-5000) to determine the percentage of the area of ​​the pores S2 relative to the total area S1 of the particle (S2 / S1) × 100, which was then defined as the cross-sectional porosity. The above cross-sectional porosity was calculated for 50 or more particles captured in the SEM observation images, and the average value was used as the cross-sectional porosity.

[0106] The obtained cross-sectional porosity values ​​are as follows: • Powder for film formation in Example 1: Cross-sectional porosity 2% • Powder for film formation in Example 2: Cross-sectional porosity 5.5% • Powder for film formation in Example 7: Cross-sectional porosity 18% • Powder for film formation in Example 8: Cross-sectional porosity 26%.

[0107] <Evaluation of the coatings> Suspension plasma spraying (SPS) was performed using the coating powders of Examples 1 to 6 and Comparative Example 1, and atmospheric plasma spraying was performed using the coating powders of Examples 7 and 8 to produce sprayed coatings.

[0108] [Preparation of thermal spray coatings by SPS] Thermal spray coatings were prepared by SPS (suspension plasma spraying) using the film-forming powders of Examples 1 to 6 and Comparative Example 1. First, the film-forming powder was added to ion-exchanged water, which is the dispersion medium, and an anionic dispersant was added to the ion-exchanged water as an additive in an amount of 0.05% by mass relative to 100% by mass of the film-forming powder. The mixture was then stirred to prepare a thermal spray slurry for SPS. The mixing ratio of the dispersion medium (ion-exchanged water) to the film-forming powder was set to a mass ratio of 7:3.

[0109] SPS was performed using the thermal spray slurry prepared as described above. A Progressive SURFACE 100HE plasma spraying system was used for SPS. A Progressive Surface LiquideerHE (product name) SPS / SPPS feed system was used as the feed system to supply the thermal spray slurry to the plasma spraying system. As the base material, a plate material (70 mm x 50 mm x 2.3 mm) made of aluminum alloy (Al6061) was used, which had been roughened by blasting with brown alumina abrasive (A#220) on its surface. The thermal spraying conditions were as follows.

[0110] [Conditions] Argon gas flow rate: 180 NL / min Nitrogen gas flow rate: 70 NL / min Hydrogen gas flow rate: 70 NL / min Plasma output: 105 kW Spray distance: 76 mm Traverse speed: 1500 mm / s Spray angle: 90° Slurry supply: 38 mL / min Number of passes: 50 passes.

[0111] [Preparation of thermal spray coatings by atmospheric pressure plasma spraying] Thermal spray coatings were prepared using the film-forming powders of Examples 7 and 8 by atmospheric pressure plasma spraying. As the substrate, a plate material (70 mm x 50 mm x 2.3 mm) made of aluminum alloy (Al6061) was used, which had been roughened by blasting with brown alumina abrasive material (A#40). The thermal spraying conditions were as follows.

[0112] [Conditions] Thermal sprayer: SG-100 (Praxair) Powder feeder: Model 1264 (Praxair) Plasma working gas: Argon gas (50 psi (0.34 MPa)) and helium gas (50 psi (0.34 MPa)) Plasma output: 36 kW Plasma generation voltage: 40 V Plasma generation current: 900 A Powder supply rate for film deposition: 20 g / min Spraying distance (distance from spray gun to substrate): 120 mm.

[0113] [Cover Porosity] The thermal spray coatings prepared using the film-forming powders of the examples and comparative examples were cut using a PRESI cutting machine (MECATOME T 210), and the cut surfaces of the small pieces were smoothed using a JEOL Handy Wrap (HLA-2). Then, the cross-sections were cut out using a JEOL CROSS SECTION POLISHER (model number: IB-19530CP). The surface perpendicular to the surface on which the thermal spray coating was formed (i.e., perpendicular to the thermal spray coating) was used as the surface to be observed (cross-section of the thermal spray coating).

[0114] The cross-sections of the thermal spray coatings were observed using a scanning electron microscope (SEM), and the pore ratio of each thermal spray coating was measured using the images obtained from the SEM observation. Specifically, images were taken using a Thermo Fisher Scientific desktop scanning electron microscope (model: Phenom Prox) to obtain cross-sectional SEM observation images. Subsequently, the percentage of pores in the total cross-sectional area (coating porosity) (%) was calculated using image analysis software included with a Keyence microscope (model: VHX-5000). The calculated coating porosity is shown in Table 1.

[0115]

[0116] As shown in Table 1, the films formed using the film-forming powders of Examples 1 to 8 have a low porosity of 2.7% or less and are highly dense. On the other hand, the film formed using the film-forming powder of Comparative Example 1 has a porosity exceeding 2.7% and is less dense.

[0117] As described above, the film-forming powder according to the present invention makes it possible to obtain a film-forming powder that can produce a highly dense film.

[0118] This application is based on Japanese Patent Application No. 2025-056407, filed on 28 March 2025, the disclosures thereof being incorporated herein by reference in their entirety.

Claims

1. Specific surface area is 2.5 m² ２ A film-forming material having a particle size of 1 / g or more and a volume-based cumulative 50% particle size (D50) of less than 10 μm.

2. The film-forming powder according to claim 1, comprising a rare earth element.

3. The film-forming powder according to claim 1 or 2, wherein the span value (D90-D10) / D50 in the volume-based particle size distribution is 1.55 or less.

4. Specific surface area is 5.0 m² ２ The film-forming powder according to claim 1 or 2, wherein the amount is 1 / g or more.

5. Specific surface area is 5.0 m² ２ / g or more 10.0m ２ The film-forming powder according to claim 1 or 2, wherein the amount is less than or equal to / g.

6. Specific surface area is 5.0 m² ２ / g or more 10.0m ２ The film-forming powder according to claim 1 or 2, wherein the amount is less than or equal to / g and the volume-based cumulative 50% particle size (D50) is 2.5 μm or less.

7. The film-forming powder according to claim 1 or 2, wherein the span value (D90-D10) / D50 in the volume-based particle size distribution is 1.30 or less.

8. The film-forming powder according to claim 1 or 2, wherein the content of particles with a particle size of less than 5 μm is 85% by mass or more.

9. The film-forming powder according to claim 1 or 2, wherein the content of particles with a particle size of 10 μm or more is 0.5% by mass or less.

10. The film-forming powder according to claim 1 or 2, which is a single oxide consisting of an oxide of a single metal element.

11. The film-forming powder according to claim 1 or 2, which is at least one of granulated sintered powder and dense powder.

12. A film formed using the film-forming powder described in claim 1 or 2.

13. A slurry comprising the film-forming powder according to claim 1 or 2 and a dispersion medium.

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