Ceramic spray particles and method for forming thermal barrier coating layer

Abstract

Ceramic thermal spray particles according to the present invention contain ZrO2 and Yb2O3, wherein the standard deviation of the content of the Yb2O3 is 2-7.0 mass%.

Description

[Technical Field]

[0001] This disclosure relates to ceramic spray particles and a method for forming a thermal barrier coating layer. This application claims priority to Japanese Patent Application No. 2022-101154, filed on June 23, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] Industrial gas turbines are being developed to be more efficient and operate at higher temperatures, and thermal barrier coatings (TBCs) applied to high-temperature components are an important element. Thermal barrier coatings are formed by, for example, plasma spraying of thermal spray materials.

[0003] Ceramic spray particles, which are thermal spray materials, are produced, for example, by a spray dryer. Patent Document 1 discloses a method for producing hollow ceramic powder for thermal spraying, which comprises preparing a raw material made of a base material of high-purity zirconium oxide (ZrO2) with a stabilizer and a surfactant, adding water to the raw material, dispersing the mixture to homogenize it, and then adding water to prepare a slurry with a raw material / water ratio of 1:1. The prepared slurry is then dropped into a high-speed rotating atomizer and splashed into particles, which are then swirled in a cyclone while being dried with high-temperature swirling air to evaporate water from the outer periphery of the particles, thereby obtaining hollow ceramic powder. The hollow ceramic powder is then sintered and solidified by heat treatment. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent No. 3825231 Summary of the Invention [Problem to be solved by the invention]

[0005] However, there is a demand for a thermal barrier coating that has a lower thermal conductivity than the thermal barrier coating using the ceramic spray particles produced by the production method described in Patent Document 1. In addition, there is also a demand for the thermal barrier coating to have high thermal cycle durability.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide ceramic spray particles and a method for forming a thermal barrier coating layer that can form a thermal barrier coating that has low thermal conductivity and excellent thermal cycle durability. [Means for solving the problem]

[0007] The ceramic spray particles according to the present disclosure are ceramic spray particles containing ZrO2 and Yb2O3, and the standard deviation of the Yb2O3 content is 2 mass % or more and 7.0 mass % or less.

[0008] The method for forming a thermal barrier coating layer according to the present disclosure includes a metal bonding layer formation step of forming a metal bonding layer on a substrate, and a ceramic layer formation step of spraying ceramic spray particles onto the metal bonding layer to form a ceramic layer, wherein the ceramic spray particles contain ZrO2 and Yb2O3, and the standard deviation of the Yb2O3 content in the ceramic spray particles is 2 mass% or more and 7.0 mass% or less. [Effects of the Invention]

[0009] According to the ceramic spray particles and the method for forming a thermal barrier coating layer according to the present disclosure, a thermal barrier coating having low thermal conductivity and excellent durability against thermal cycles can be formed. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic cross-sectional view of a heat-resistant member according to the present disclosure. [Figure 2] 1 is a flowchart of a method for forming a thermal barrier coating layer according to the present disclosure. [Figure 3]1 is a flowchart of a method for producing ceramic spray particles according to the present disclosure. [Figure 4] FIG. 1 is a schematic cross-sectional view of a laser-type thermal cycle testing device. [Figure 5] FIG. 10 is a graph showing the relationship between thermal conductivity and the standard deviation of Yb2O3 in ceramic spray particles. [Figure 6] FIG. 10 is a graph showing the relationship between thermal cycle durability and the standard deviation of Yb2O3 in ceramic spray particles. [Figure 7] FIG. 1 is a graph showing the relationship between thermal cycle durability and the cumulative particle size d10 of ceramic spray particles. DETAILED DESCRIPTION OF THE INVENTION

[0011] <Heat-resistant materials> A heat-resistant component having a thermal barrier coating layer according to the present disclosure formed thereon will now be described. Fig. 1 is a schematic cross-sectional view of a heat-resistant component 10 according to the present disclosure. The heat-resistant component 10 comprises a substrate 21, a metallic bonding layer 22 formed on the substrate 21, and a ceramic layer 23 formed on the metallic bonding layer 22. The thermal barrier coating layer 20 comprises the metallic bonding layer 22 and the ceramic layer 23.

[0012] (Base material 21) The substrate 21 is a high-temperature heat-resistant alloy substrate used for, for example, rotor blades. The chemical composition of the substrate 21 is, for example, in mass %, Ni: 20 to 40 mass %, Cr: 10 to 30 mass %, Al: 4 to 15 mass %, Y: : The content is 0.1 to 5 mass %, Re: 0.5 to 10 mass %, and the remainder is Co. In this specification, a numerical range expressed using "to" means a range that includes the numerical values written before and after "to" as the lower and upper limits. Numerical values indicated as "less than" and "greater than" do not include the value in the numerical range.

[0013] (Metal bonding layer 22) The metallic bonding layer 22 is formed directly on the substrate 21. The metallic bonding layer 22 reduces the difference in thermal expansion coefficient between the substrate 21 and the ceramic layer 23, alleviating thermal stress. This prevents the ceramic layer 23 from peeling off from the metallic bonding layer 22. The metallic bonding layer 22 also prevents high-temperature oxidation and corrosion of the substrate 21. It is preferable to use a material with excellent corrosion resistance and oxidation resistance for the metallic bonding layer 22. The metallic bonding layer 22 is made of an MCrAlY alloy or the like. The M in the MCrAlY alloy represents a metal element, and indicates, for example, a single metal element such as Ni, Co, or Fe, or two or more of these metal elements.

[0014] (ceramic layer) The ceramic layer 23 is made of ZrO2 partially stabilized with Yb2O3 (hereinafter referred to as YbSZ). The ceramic layer 23 may contain impurities other than Yb2O3 and ZrO2. The impurities may be, for example, components mixed in the raw materials or components mixed in during the manufacturing process. The ceramic layer 23 made of YbSZ has excellent crystal stability, and therefore can also suppress the generation of stress due to phase transformation.

[0015] The ZrO2 content is 75 mass% or more, based on the total mass of the thermal barrier coating layer 20. The ZrO2 content is more preferably 80 mass% or more. The ZrO2 content is 90 mass% or less. The ZrO2 content is more preferably 84 mass% or less.

[0016] The content of Yb2O3 is preferably 10 mass% or more relative to the total mass of the thermal barrier coating layer 20. When the content of Yb2O3 is 10 mass% or more, the thermal cycle durability of the thermal barrier coating layer 20 is improved. The content of Yb2O3 is more preferably 16 mass% or more. The content of Yb2O3 is preferably 25 mass% or less. If the content of Yb2O3 exceeds 25 mass%, the durability of the thermal barrier coating layer 20 may decrease. The content of Yb2O3 is more preferably 20 mass% or less.

[0017] The standard deviation of the Yb2O3 content in the ceramic layer 23 is 2% by mass or more and 7.0% by mass or less. If the standard deviation of the Yb2O3 content is less than 2% by mass, the thermal conductivity of the ceramic layer 23 increases, which is not preferable. If the standard deviation of the Yb2O3 content is more than 7.0% by mass, the thermal cycle durability decreases, which is not preferable.

[0018] The chemical compositions of the metal bonding layer 22 and the ceramic layer 23 can be analyzed using known methods. For example, a cross section of an observation sample obtained by cutting the heat-resistant member 10 is analyzed at 10 random locations using an electron probe microanalyzer. The YbO content and ZrO content are calculated from the obtained Yb and Zr contents (atomic %). The average value of the obtained YbO content is defined as the YbO content. The average value of the ZrO content is also defined as the ZrO content. At the same time, the standard deviation of YbO and the standard deviation of ZrO can also be evaluated in the same way.

[0019] The porosity of the ceramic layer 23 is preferably 4% or more and 20% or less. The porosity of the ceramic layer 23 means the area ratio of pores in the ceramic layer 23. The porosity can be determined, for example, by observing a cross section of the ceramic layer 23 at random five fields of view (observation length of approximately 3 mm) using an optical microscope (magnification 100x) and using an image processing method.

[0020] The thickness of the ceramic layer 23 is preferably 0.1 to 1.5 mm. If the thickness of the ceramic layer 23 is less than 0.1 mm, the heat-shielding properties of the ceramic layer 23 may be insufficient. If the thickness of the ceramic layer 23 exceeds 5 mm, the ceramic layer 23 may peel off easily, and the durability of the ceramic layer 23 may decrease.

[0021] The above describes the heat-resistant member 10. By forming the ceramic layer 23 from ZrO2 stabilized with Yb2O3, the crystal stability of the ceramic layer 23 is improved, and even when used in high-temperature components such as turbines, the crystal phase of the ceramic layer 23 is less likely to change during thermal cycles, making it possible to prevent cracks due to phase transformation and their propagation.

[0022] <Method for forming a thermal barrier coating layer> A method for forming the thermal barrier coating layer 20 according to the present disclosure will now be described. FIG. 2 is a flowchart of the method for forming the thermal barrier coating layer 20. The method for forming the thermal barrier coating layer 20 includes a metallic bonding layer forming step S1 for forming a metallic bonding layer 22 on a substrate 21, and a metallic bonding layer forming step S2. rear and a ceramic layer forming step S2 of forming a ceramic layer 23 by thermally spraying ceramic spray particles onto the metal bonded layer 22.

[0023] (Metal bonding layer formation step S1) In the metallic bonding layer formation step S1, a metallic bonding layer 22 is formed on the substrate 21. The method for forming the metallic bonding layer 22 is not particularly limited. The metallic bonding layer 22 can be formed by a low-pressure plasma spraying method, an electron beam physical vapor deposition method, or the like. Note that the substrate 21 on which the metallic bonding layer 22 has been formed in advance may be prepared as the substrate for thermal spraying.

[0024] (Ceramic layer formation process S2) In the ceramic layer forming step S2, a ceramic layer 23 is formed on the metal bonding layer 22. The ceramic layer 23 is formed by thermally spraying ceramic spray particles onto the metal bonding layer 22. shape The thermal spraying method is not particularly limited, but for example, low-pressure plasma spraying can be used.

[0025] (ceramic spray particles) Next, the ceramic spray particles used in the ceramic layer forming step S2 will be described. The ceramic spray particles of the present disclosure contain zirconium oxide (ZrO2) and ytterbia (Yb2O3).

[0026] In the ceramic spray particles, the ZrO2 content is 75 mass% or more relative to the total mass of the ceramic spray particles. The ZrO2 content is more preferably 80 mass% or more. The ZrO2 content is 90 mass% or less. The ZrO2 content is more preferably 84 mass% or less.

[0027] The Yb2O3 content is preferably 10 mass% or more relative to the total mass of the ceramic spray particles. A Yb2O3 content of 10 mass% or more improves the durability (thermal cycle durability) of the thermal barrier coating layer 20. A more preferred Yb2O3 content is 16 mass% or more. A Yb2O3 content of 25 mass% or less is preferred. If the Yb2O3 content exceeds 25 mass%, the durability of the thermal barrier coating layer 20 may decrease. A more preferred Yb2O3 content is 20 mass% or less.

[0028] In the ceramic spray particles, the standard deviation of the Yb2O3 content is 2% by mass or more and 7.0% by mass or less. If the standard deviation of the Yb2O3 content is less than 2% by mass, the thermal conductivity of the ceramic layer 23 will be high, which is undesirable. More preferably, the standard deviation of the Yb2O3 content is 2.0% by mass or more relative to the total mass of the ceramic spray particles. Even more preferably, the standard deviation of the Yb2O3 content is 2.3% by mass or more. The standard deviation of the Yb2O3 content is preferably 5.3% by mass or less. If the standard deviation of the Yb2O3 content exceeds 7.0% by mass, the thermal cycle durability will decrease, which is undesirable.

[0029] The in-plane distribution of the chemical composition of ceramic spray particles can be analyzed using known methods. For example, ceramic spray particles are embedded in resin and cut. The cut cross section is polished to prepare a specimen for observation. The cross section of the obtained specimen is subjected to point analysis at 10 random locations using an electron probe microanalyzer. The Yb2O3 content and ZrO2 content are calculated from the obtained Yb and Zr contents (atomic %). The average value of the obtained Yb2O3 content is taken as the Yb2O3 content. The average value of the ZrO2 content is also taken as the ZrO2 content. At the same time, the standard deviation of Yb2O3 and the standard deviation of ZrO2 are also evaluated in the same way.

[0030] The cumulative particle size d10 of the ceramic spray particles is preferably 40 μm or more. More preferably, the cumulative particle size d10 of the ceramic spray particles is 45 μm or more. When the cumulative particle size d10 of the ceramic spray particles is 40 μm or more, the porosity of the ceramic layer 23 is improved and the thermal cycle durability of the ceramic layer 23 can be further improved. The cumulative particle size d10 of the ceramic spray particles is preferably 100 μm or less. More preferably, the cumulative particle size d10 of the ceramic spray particles is 51 μm. The cumulative particle size d10 can be measured based on JIS Z 8825:2013. The cumulative particle size d10 refers to the particle size below which 10% of the population lies. The cumulative particle size d10 refers to the particle size that is 10% of the total particle size from the small particle size side on the volume distribution curve.

[0031] The maximum particle size of the ceramic spray particles is preferably 150 μm or less. By setting the maximum particle size of the ceramic spray particles to 150 μm or less, the ceramic spray particles can be easily melted in plasma spraying. The maximum particle size of the ceramic spray particles is the particle size represented by the smallest opening of a metal mesh sieve through which all of the ceramic spray particles can pass.

[0032] The ceramic spray particles of the present disclosure are preferably hollow. If the ceramic spray particles are hollow, the porosity of the ceramic layer 23 is improved, and the heat-shielding properties can be further improved.

[0033] The foregoing has described the disclosed ceramic spray particles and the method for forming the thermal barrier coating layer 20. The disclosed ceramic spray particles and the method for forming the thermal barrier coating layer 20 make it possible to form a thermal barrier coating that has low thermal conductivity and excellent durability against thermal cycles.

[0034] <Method for manufacturing ceramic spray particles> Next, a method for producing ceramic spray particles according to the present disclosure will be described. Fig. 3 is a flowchart of the method. The method for producing ceramic spray particles according to the present disclosure includes a mixing step S11 in which ZrO2 powder, a predetermined proportion of Yb2O3 powder, and water are mixed to produce a slurry, a powder formation step S12 in which powder is produced from the slurry, a solid solution formation step S13 in which the powder is solid-solutioned, and a classification step S14 in which the powder after solid solution formation is classified.

[0035] (Mixing process S11) In the mixing step S11, a slurry is produced by mixing ZrO2 powder and Yb2O3 powder in the aforementioned ratio with water so that the standard deviation of the Yb2O3 content in the ceramic spray particles is 2% by mass or more and 7.0% by mass or less. It is preferable to add a surfactant to the raw materials (ZrO2 powder, Yb2O3 powder, and water). Adding the surfactant can promote re-separation of aggregated ZrO2 powder and Yb2O3 powder. The weight ratio of ZrO2 powder and Yb2O3 powder to water is not particularly limited, but is, for example, 1:1. It is preferable to add water and a binder to the slurry before the powder formation step S12.

[0036] The raw materials can be mixed using, for example, a ball mill, a bead mill, or the like. When a bead mill is used, the mixing time is, for example, 8 to 10 hours. If the mixing time is too long, the standard deviation of the Yb2O3 content will be less than 2 mass%, and the thermal conductivity of the ceramic layer 23 will increase. If the mixing time is too short, the standard deviation will exceed 7 mass%, and the thermal cycle durability of the ceramic layer 23 will decrease. The mixing conditions vary depending on the mixing device, so it is preferable to adjust them appropriately to suit the device.

[0037] When a bead mill is used, the rotation speed during mixing of the raw materials is, for example, 10 to 30 rpm, and can be adjusted appropriately depending on the mixing device.

[0038] (Powder formation process S12) In the powder formation step S12, powder is produced from the slurry obtained in the mixing step S11. Specifically, the powder is produced by spray-drying the slurry. The spray-drying method is not particularly limited. For example, in the case of the spin disk method, the disk is rotated at high speed (10,000 rpm), causing the slurry to form spherical shapes and be ejected. The spherical slurry is then dried and rotated by high-temperature swirling air (approximately 200°C). During this process, the slurry gradually dries from the outside in the dry air and solidifies. Because the raw material particles in the slurry are coarse, water evaporates from the gaps between the raw material particles. This allows for the production of hollow ceramic spray particles.

[0039] (Solid solution process S13) In the solid solution forming step S13, the powder obtained in the powder forming step S12 is solid-solutionized. Specifically, the obtained powder is heat-treated in a heat treatment furnace at 1450°C for 10 hours. The temperature at this time is the set temperature of the heat treatment furnace. This heat treatment causes ZrO2 and Yb2O3 to diffuse and form a solid solution, thereby obtaining strength suitable for thermal spraying.

[0040] (Classification process S14) In the classification step S14, the powder after solid solution formation is classified to obtain ceramic spray particles. In the classification step S14, it is preferable to classify the particles into particles with a particle size of 150 μm or less. That is, it is preferable to set the maximum particle size of the ceramic spray particles to 150 μm or less. If the particle size of the ceramic spray particles exceeds 150 μm, they may not melt well during the plasma spraying process. Furthermore, in the classification step S14, it is preferable to remove small particle sizes of ceramic spray particles so that the cumulative particle size d10 is 40 μm or more. The classification method is not particularly limited, and for example, a gyro shifter can be used.

[0041] The method for producing ceramic spray particles according to the present disclosure has been described above. The method for producing ceramic spray particles according to the present disclosure can produce ceramic spray particles that can form a thermal barrier coating having low thermal conductivity and excellent durability against thermal cycles.

[0042] The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. In addition, the components in the above-described embodiments can be replaced with well-known components as appropriate without departing from the spirit of the present invention. [Example]

[0043] Next, examples of the present invention will be described, but the conditions in the examples are merely examples adopted to confirm the feasibility and effects of the present invention, and the present invention is not limited to these examples. Various conditions can be adopted in the present invention as long as they do not deviate from the gist of the present invention and the object of the present invention is achieved.

[0044] Example 1 The mass ratio of ZrO2, Yb2O3, water, and surfactant was set to 84:16:100:1, and mixing was performed using a bead mill at 18 rpm for 8 hours to prepare a slurry, to which water and binder were added in a mass ratio of 50:2. Powder was prepared from the slurry by spray drying, and the obtained powder was heated in a heat treatment furnace at 1450°C for 10 hours. The obtained powder was classified (40 μm to 150 μm) to obtain the ceramic spray particles of Example 1. The ceramic spray particles of Example 1 were embedded in resin and cut. Observation of the cross section revealed that the ceramic spray particles of Example 1 were hollow particles. Measurements using the method described below showed that the standard deviation of the Yb2O3 concentration relative to the total mass of the ceramic spray particles of Example 1 was ±2.6 mass%, and the 10% cumulative particle size d10 of the ceramic spray particles of Example 1 was 43 μm.

[0045] Example 2 The mass ratio of ZrO2, Yb2O3, water, and surfactant was set to 84:16:100:1, and mixing was performed using a bead mill at 25 rpm for 8 hours to prepare a slurry, to which water and binder were added in a mass ratio of 50:2. Powder was produced from the slurry by spray drying, and the resulting powder was heated in a heat treatment furnace at 1450°C for 10 hours. The resulting powder was classified to obtain the ceramic spray particles of Example 2. The ceramic spray particles of Example 2 were embedded in resin and cut. Observation of the cross section revealed that the ceramic spray particles of Example 2 were hollow particles. Measurements using the method described below showed that the standard deviation of the Yb2O3 concentration relative to the total mass of the ceramic spray particles of Example 2 was ±2.3 mass%, and the 10% cumulative particle size d10 of the ceramic spray particles of Example 2 was 49 μm.

[0046] Example 3 The mass ratio of ZrO2, Yb2O3, water, and surfactant was set to 84:16:100:1, and a bead mill was used to mix for 8 hours at a rotation speed of 5 rpm to produce a slurry, to which water and binder were added in a mass ratio of 50:2. Powder was produced from the slurry by spray drying, and the obtained powder was heated in a heat treatment furnace at 1450°C for 10 hours. The obtained powder was classified (40 μm to 150 μm), and the results are shown in the examples. 3 The ceramic spray particles of Example 3 were embedded in resin and cut. Observation of the cross section revealed that the ceramic spray particles of Example 3 were hollow particles. Measurements using the method described below revealed that the standard deviation of the Yb2O3 concentration relative to the total mass of the ceramic spray particles of Example 3 was ±5.3 mass%, and the 10% cumulative particle diameter d10 of the ceramic spray particles of Example 3 was 43 μm.

[0047] Example 4 The mass ratio of ZrO2, Yb2O3, water, and surfactant was set to 84:16:100:1, and mixing was performed using a bead mill for 10 hours at 25 rpm to prepare a slurry, to which water and binder were added in a mass ratio of 50:2. Powder was prepared from the slurry by spray drying, and the obtained powder was heated in a heat treatment furnace at 1450°C for 10 hours. The obtained powder was classified (40 μm to 150 μm) to obtain the ceramic spray particles of Example 4. The ceramic spray particles of Example 4 were embedded in resin and cut. Observation of the cross section revealed that the ceramic spray particles of Example 4 were hollow particles. Measurements using the method described below showed that the standard deviation of the Yb2O3 concentration relative to the total mass of the ceramic spray particles of Example 4 was ±2.5 mass%, and the 10% cumulative particle size d10 of the ceramic spray particles of Example 4 was 51 μm.

[0048] (Comparative Example 1) The mass ratio of ZrO2, Yb2O3, water, and surfactant was 84:16:100:1. Mixing was performed using a bead mill for 15 hours at 10 rpm to prepare a slurry, to which water and binder were added in a mass ratio of 50:2. Powder was prepared from the slurry by spray drying, and the resulting powder was heated in a heat treatment furnace at 1450°C for 10 hours. The resulting powder was classified (40 μm to 150 μm) to obtain the ceramic spray particles of Comparative Example 1. The ceramic spray particles of Comparative Example 1 were embedded in resin and cut. Observation of the cross section revealed that the ceramic spray particles of Comparative Example 1 were hollow particles. Measurements using the method described below showed that the standard deviation of the Yb2O3 concentration relative to the total mass of the ceramic spray particles of Comparative Example 1 was ±0.2 mass%, and the 10% cumulative particle diameter d10 of the ceramic spray particles of Comparative Example 1 was 43 μm.

[0049] (Comparative Example 2) The mass ratio of ZrO2, Yb2O3, water, and surfactant was set to 84:16:100:1, and mixing was performed using a bead mill for 15 hours at 25 rpm to prepare a slurry, to which water and binder were added in a mass ratio of 50:2. Powder was prepared from the slurry by spray drying, and the obtained powder was heated in a heat treatment furnace at 1450°C for 10 hours. The obtained powder was classified (40 μm to 150 μm) to obtain the ceramic spray particles of Comparative Example 2. The ceramic spray particles of Comparative Example 2 were embedded in resin and cut. Observation of the cross section revealed that the ceramic spray particles of Comparative Example 2 were hollow particles. Measurements using the method described below showed that the standard deviation of the Yb2O3 concentration relative to the total mass of the ceramic spray particles of Comparative Example 2 was ±1.2 mass%, and the 10% cumulative particle size d10 of the ceramic spray particles of Comparative Example 2 was 46 μm.

[0050] (Comparative Example 3) The mass ratio of ZrO2, Yb2O3, water, and surfactant was set to 84:16:100:1, and mixing was performed using a bead mill for 15 hours at 25 rpm to prepare a slurry, to which water and binder were added in a mass ratio of 50:2. Powder was prepared from the slurry by spray drying, and the powder was classified (40 μm to 150 μm) without heat treatment to obtain the ceramic spray particles of Comparative Example 3. The ceramic spray particles of Comparative Example 3 were embedded in resin and cut. Observation of the cross section revealed that the ceramic spray particles of Comparative Example 3 were hollow particles. Measurements using the method described below showed that the standard deviation of the Yb2O3 concentration relative to the total mass of the ceramic spray particles of Comparative Example 3 was ±7.3 mass%, and the 10% cumulative particle size d10 of the ceramic spray particles of Comparative Example 3 was 50 μm.

[0051] (Formation of thermal barrier coating layer) The test specimens used were 5 mm thick heat-resistant alloy substrates (trade name: IN-738LC) with a 100 μm thick metallic bonding layer (Ni: 32 mass %, Cr: 21 mass %, Al: 8 mass %, Y: 0.5 mass %, Co: balance) formed by low-pressure plasma spraying. Using the ceramic spray particles of Examples 1 to 4 and Comparative Examples 1 to 3 produced above, a ceramic layer (YbSZ layer) was laminated on the metallic bonding layer by atmospheric plasma spraying to form a thermal barrier coating layer. The thickness of the metallic bonding layer (CoNiCrAlY) and the thickness of the ceramic layer (YbSZ) were the same for all samples, at 0.1 mm and 0.5 mm, respectively.

[0052] (Standard deviation of Yb2O3 content in ceramic spray particles) The standard deviation of the Yb2O3 content was measured for each of the ceramic spray particles of Examples 1 to 4 and Comparative Examples 1 to 3. Specifically, the measurement was performed by the following method. The obtained ceramic spray particles were embedded in resin and cut. The cut cross section was polished, and the polished cross section was subjected to point analysis at 10 random locations using an electron probe microanalyzer. The Yb2O3 content and ZrO2 content were calculated from the Yb and Zr contents (atomic %) obtained from the point analysis, and the standard deviation was determined.

[0053] (Cumulative particle size d10 of ceramic spray particles) The particle size distribution of each of the ceramic spray particles in Examples 1 to 4 and Comparative Examples 1 to 3 was measured using a laser scattering diffraction particle size distribution analyzer (manufactured by Microtrac). The cumulative particle size d10 of each of the ceramic spray particles in Examples 1 to 4 and Comparative Examples 1 to 3 was obtained from the obtained particle size distribution. The maximum particle size of the ceramic spray particles was measured using a mesh. The maximum particle size of the ceramic spray particles in Examples 1 to 4 and Comparative Examples 1 to 3 was 150 μm.

[0054] (thermal conductivity) The thermal conductivity of the thermal barrier coating layers of Examples 1 to 4 and Comparative Examples 1 to 3 was measured by the laser flash method specified in JIS R1611:2010.

[0055] (thermal cycle durability) The thermal cycle durability of the thermal barrier coating layers using the ceramic spray particles obtained above in Examples 1 to 4 and Comparative Examples 1 to 3 was evaluated. FIG. 4 is a schematic cross-sectional view of a laser-type thermal cycle testing apparatus used to evaluate the thermal cycle durability. In the laser-type thermal cycle testing apparatus shown in this figure, a sample 31, which had a thermal barrier coating layer 20 formed on a substrate 21, was placed on a sample holder 32 disposed on a main body 33, with the thermal barrier coating layer 20 facing outward. Laser light L from a CO2 laser device 30 was irradiated onto the sample 31, heating the sample 31 from the thermal barrier coating layer 20 side. Simultaneously with heating by the laser device 30, the sample 31 was cooled from its back side by a gas flow F discharged from the tip of a cooling gas nozzle 34, which penetrated the main body 33 and was disposed inside the main body 33 at a position facing the back side of the sample 31.

[0056] The heating time was 3 minutes, the cooling time was 3 minutes, and the maximum surface temperature was 900°C. Various maximum surface heating temperatures were set, and the number of thermal cycles until the ceramic layer peeled off was measured. The highest temperature among the surface heating temperatures at which 1000 cycles were completed was taken as the 1000 cycle end temperature. A higher 1000 cycle end temperature indicates higher thermal cycle durability.

[0057] Figure 5 shows the relationship between the thermal conductivity of the thermal barrier coating layer and the standard deviation of Yb2O3 in the ceramic spray particles. The horizontal axis of Figure 5 represents the standard deviation (±mass%) of Yb2O3 in the ceramic spray particles, and the vertical axis represents thermal conductivity (kcal / mh°C). When the standard deviation of Yb2O3 in the ceramic spray particles was less than 2.0% (Comparative Examples 1 and 2), the thermal conductivity tended to be high. It is presumed that the longer stirring time in Comparative Examples 1 and 2 resulted in a uniform mixing of the materials, resulting in higher thermal conductivity. On the other hand, when the standard deviation of Yb2O3 was 2.0% or more, the thermal conductivity tended to be low. It is presumed that this is because the large standard deviation (variation) of Yb2O3 made it easier for heat scattering to occur at the interface between different phases, resulting in lower thermal conductivity.

[0058] Figure 6 shows the relationship between the thermal cycle durability of the thermal barrier coating layer and the standard deviation of Yb2O3 in the ceramic spray particles. The horizontal axis of Figure 6 represents the standard deviation (±% by mass) of Yb2O3 in the ceramic spray particles, and the vertical axis of Figure 6 represents the 1000-cycle turnover temperature (°C). Examples 1 to 4 and Comparative Examples 1 and 2 exhibited sufficient thermal cycle durability, but the 1000-cycle turnover temperature of Comparative Example 3 was below 600°C. It is presumed that the thermal cycle durability of Comparative Example 3 was low due to the large variation in Yb2O3 in the ceramic spray particles.

[0059] Figure 7 shows the relationship between the thermal cycle durability of the thermal barrier coating layer and the cumulative particle size d10 of the ceramic spray particles. The horizontal axis of Figure 7 represents the cumulative particle size d10 (μm) of the ceramic spray particles, and the vertical axis of Figure 7 represents the 1000 cycle turnover temperature (°C). As shown in Figure 7, the 1000 cycle turnover temperature increased as the cumulative particle size d10 of the ceramic spray particles increased. In particular, when the cumulative particle size d10 was 45 μm or more, high thermal cycle durability of 700°C was observed.

[0060] From the above results, it was confirmed that by using the ceramic spray particles and the method for forming a thermal barrier coating layer disclosed herein, it is possible to form a thermal barrier coating that has low thermal conductivity and excellent thermal cycle durability.

[0061] <Additional Notes> The ceramic spray particles and the method for forming a thermal barrier coating layer described in the above embodiment can be understood as follows.

[0062] (1) The ceramic spray particles according to the first aspect of the present disclosure are ceramic spray particles containing ZrO2 and Yb2O3, and the standard deviation of the Yb2O3 content is 2 mass% or more and 7.0 mass% or less.

[0063] In this way, a thermal barrier coating having low thermal conductivity and excellent durability against thermal cycles can be formed.

[0064] (2) The ceramic spray particles according to a second embodiment of the present disclosure are the ceramic spray particles of (1), in which the Yb2O3 content is 16 mass % or more, in mass % relative to the total mass of the ceramic spray particles.

[0065] This improves the thermal cycle durability of the thermal barrier coating layer 20.

[0066] (3) The ceramic spray particles according to the third embodiment of the present disclosure are the ceramic spray particles according to (1) or (2), and have an integrated particle size d10 of 40 μm or more.

[0067] By doing so, the thermal cycle durability of the thermal barrier coating layer 20 is further improved.

[0068] (4) The ceramic spray particles according to a fourth aspect of the present disclosure are the ceramic spray particles according to (3), in which the cumulative particle diameter d10 is 45 μm or more.

[0069] By doing so, the thermal cycle durability of the thermal barrier coating layer 20 is further improved.

[0070] (5) A method for forming a thermal barrier coating layer according to a fifth aspect of the present disclosure includes a metal bonding layer formation step S1 for forming a metal bonding layer on a substrate, and a ceramic layer formation step S2 for spraying ceramic spray particles onto the metal bonding layer to form a ceramic layer, wherein the ceramic spray particles contain ZrO2 and Yb2O3, and the standard deviation of the Yb2O3 content in the ceramic spray particles is 2 mass% or more and 7.0 mass% or less.

[0071] In this way, a thermal barrier coating having low thermal conductivity and excellent durability against thermal cycles can be formed.

[0072] (6) A sixth aspect of the present disclosure relates to a method for forming a thermal barrier coating layer, which is a method for forming a thermal barrier coating layer according to (5), in which the content of the Yb2O3 is 16 mass% or more, in mass% relative to the total mass of the ceramic spray particles.

[0073] By doing so, the thermal cycle durability of the thermal barrier coating layer 20 is further improved.

[0074] (7) A method for forming a thermal barrier coating layer according to a seventh aspect of the present disclosure is the method for forming a thermal barrier coating layer according to (5) or (6), wherein the cumulative particle size d10 of the ceramic spray particles is 40 μm or more.

[0075] By doing so, the thermal cycle durability of the thermal barrier coating layer 20 is further improved.

[0076] (8) A method for forming a thermal barrier coating layer according to an eighth aspect of the present disclosure is the method for forming a thermal barrier coating layer according to (7), wherein the cumulative grain size d10 is 45 μm or more.

[0077] By doing so, the thermal cycle durability of the thermal barrier coating layer 20 is further improved. [Industrial Applicability]

[0078] According to the ceramic spray particles and the method for forming a thermal barrier coating layer of the present disclosure, a thermal barrier coating having low thermal conductivity and excellent durability against thermal cycles can be formed. [Explanation of symbols]

[0079] S1 Metal bonding layer formation process, S2 Ceramic layer formation process, S11 Mixing process, S12 Powder formation process, S13 Solid solution formation process, S14 Classification process

Claims

1. ZrO ２ and Yb ２ O ３ Ceramic spray particles containing The Yb ２ O ３ The ceramic spray particles have a standard deviation of the content of 2 mass% or more and 7.0 mass% or less.

2. In mass % relative to the total mass of the ceramic spray particles, The Yb ２ O ３ The ceramic spray particles according to claim 1, wherein the content of is 16 mass % or more.

3. The ceramic spray particles according to claim 1 or 2, wherein the cumulative particle diameter d10 is 40 μm or more.

4. The ceramic spray particles according to claim 3, wherein the cumulative particle diameter d10 is 45 μm or more.

5. a metal bonding layer forming step of forming a metal bonding layer on the substrate; a ceramic layer forming step of spraying ceramic spray particles onto the metal bonded layer to form a ceramic layer, The ceramic spray particles are ZrO ２ and Yb ２ O ３ and The Yb in the ceramic spray particles ２ O ３ The standard deviation of the content of is 2 mass % or more and 7.0 mass % or less.

6. In mass % relative to the total mass of the ceramic spray particles, The Yb ２ O ３ The method for forming a thermal barrier coating layer according to claim 5 , wherein the content of is 16 mass % or more.

7. 7. The method for forming a thermal barrier coating layer according to claim 5, wherein the ceramic spray particles have an integrated particle size d10 of 40 μm or more.

8. The method for forming a thermal barrier coating layer according to claim 7, wherein the cumulative grain size d10 is 45 μm or more.

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