(Hf, Zr, Ta, Ti)B2-SiC ceramic powder and a preparation method thereof

Abstract

This invention provides a (Hf,Zr,Ta,Ti)B2-SiC ceramic powder and its preparation method, belonging to the field of high-entropy boride ceramics technology. This invention uses excess B4C powder to ensure more complete reaction of the metal oxide powder, forming a single-phase (Hf,Zr,Ta,Ti)B2 ceramic powder without impurity formation. Using SiC powder as a filler phase further improves both the density and bulk density of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder. Spray granulation further enhances the flowability of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder, ensuring that the resulting (Hf,Zr,Ta,Ti)B2-SiC ceramic powder, when coated using plasma spraying technology, achieves a high density of the (Hf,Zr,Ta,Ti)B2-SiC ceramic coating.

Description

Technical Field

[0001] This invention relates to the field of high-entropy boride ceramics technology, and in particular to a (Hf,Zr,Ta,Ti)B2-SiC ceramic powder and its preparation method. Background Technology

[0002] Carbon-based composite materials, due to their superior properties such as high strength, high modulus, high fracture toughness, excellent thermal insulation, and low density, are widely used in key components in the aerospace, aviation, and defense fields. However, carbon-based composite materials undergo severe oxidation and ablation in high-temperature and oxygen-containing environments, causing a sharp decline in their performance. Therefore, high-entropy boride (HEB) ceramic coatings have been developed, which involves preparing HEB ceramic materials as a coating on the surface of carbon-based composite materials. This coating possesses comprehensive properties such as resistance to extremely high temperatures, resistance to oxidation and ablation, and long lifespan, making it one of the key technologies for new aerospace vehicles. Currently, there are many technologies for preparing ultra-high temperature ceramic coatings. Among them, plasma spraying technology melts or softens HEB ceramic powder using ultra-high temperature plasma, and then sprays it onto the surface of carbon-based composite materials using a high-speed gas stream to form a coating. This technology has the advantage of high preparation efficiency and is widely used.

[0003] Currently, commonly used high-entropy borides include borides of transition metals such as Nb, Ti, Cr, W, Hf, Zr, or Ta. Among them, the borides of Hf, Zr, Ta, and Ti all have hexagonal crystal structures, melting points above 3000℃, and low oxygen diffusion coefficients in their oxides, thus making them the main elements of high-entropy boride ceramics. Existing technologies typically use the boronothermal reduction method to prepare (Hf,Zr,Ta,Ti)B2 ceramic powder. However, the resulting product usually contains boron oxide or undissolved transition metal oxide impurities, leading to low density in the high-entropy boride ceramic powder itself, which in turn affects the density of the resulting high-entropy boride ceramic coating. Furthermore, due to its high hardness and poor formability, (Hf,Zr,Ta,Ti)B2 ceramic powder exhibits poor bulk density and flowability when used for plasma spraying, resulting in low density and poor uniformity in the prepared high-entropy boride ceramic coating. Summary of the Invention

[0004] The purpose of this invention is to provide a (Hf,Zr,Ta,Ti)B2-SiC ceramic powder and its preparation method. The (Hf,Zr,Ta,Ti)B2-SiC ceramic powder provided by this invention is free of impurities, has high density, and good loose density and flowability. The (Hf,Zr,Ta,Ti)B2-SiC ceramic coating obtained by plasma spraying has high density.

[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0006] This invention provides a method for preparing (Hf,Zr,Ta,Ti)B2-SiC ceramic powder, comprising the following steps:

[0007] (1) Metal oxide powder and B4C powder are ball-milled and mixed sequentially, and then subjected to thermal reduction reaction to obtain (Hf,Zr,Ta,Ti)B2 ceramic powder; the metal oxide powder includes HfO2 powder, ZrO2 powder, Ta2O5 powder and TiO2 powder; the molar ratio of the metal oxide powder to B4C powder is 3.5:(0.55~0.65);

[0008] (2) The (Hf,Zr,Ta,Ti)B2 ceramic powder, SiC powder and water-soluble binder obtained in step (1) are mixed and then ball-milled to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry;

[0009] (3) Spray granulation is performed on the (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry obtained in step (2) to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic powder.

[0010] Preferably, the temperature of the thermal reduction reaction in step (1) is 1800-2000℃, and the time of the thermal reduction reaction is 1-3h.

[0011] Preferably, in step (2), the volume ratio of (Hf,Zr,Ta,Ti)B2 ceramic powder to SiC powder is (2.3-9):1.

[0012] Preferably, the particle size of the SiC powder in step (2) is 1 to 3 μm.

[0013] Preferably, the particle size of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder in step (2) is 200-400 mesh.

[0014] Preferably, the mass content of the water-soluble binder in step (2) is 0.2% to 0.5% of the total mass of (Hf,Zr,Ta,Ti)B2 ceramic powder and SiC powder.

[0015] Preferably, the water-soluble binder in step (2) includes polyvinyl alcohol, polyurethane, polyethylene glycol or water glass.

[0016] Preferably, in step (3), the inlet temperature of the spray granulation is 240-270°C, the outlet temperature of the spray granulation is 135-160°C, the peristaltic pump speed of the spray granulation is 30-50 r / min, and the nozzle speed of the spray granulation is 30-50 r / min.

[0017] This method also provides (Hf,Zr,Ta,Ti)B2-SiC ceramic powder prepared by the preparation method described in the above technical solution.

[0018] Preferably, the particle size of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder is 200-400 mesh.

[0019] The present invention also provides a (Hf,Zr,Ta,Ti)B2-SiC ceramic coating, which is obtained by plasma spraying of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder described in the above technical solution.

[0020] This invention provides a method for preparing (Hf,Zr,Ta,Ti)B2-SiC ceramic powder, comprising the following steps: (1) ball milling and mixing metal oxide powder and B4C powder, followed by thermal reduction reaction to obtain (Hf,Zr,Ta,Ti)B2 ceramic powder; wherein the metal oxide powder includes HfO2 powder, ZrO2 powder, Ta2O5 powder and TiO2 powder; wherein the molar ratio of the metal oxide powder to B4C powder is 3.5:(0.55~0.65); (2) ball milling the (Hf,Zr,Ta,Ti)B2 ceramic powder, SiC powder and water-soluble binder obtained in step (1) to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry; (3) spray granulation of the (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry obtained in step (2) to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic powder. In this invention, B4C powder is directly reacted with HfO2 powder, ZrO2 powder, Ta2O5 powder, and TiO2 powder to generate (Hf,Zr,Ta,Ti)B2 in one step. This reduces the possibility of interdiffusion caused by the reaction of boron carbide with HfO2 powder, ZrO2 powder, Ta2O5 powder, and TiO2 powder to form corresponding borides, avoiding the generation of second-phase impurities due to uneven diffusion and improving the density of (Hf,Zr,Ta,Ti)B2 ceramic powder. Using SiC powder as a filler phase further improves the density of (Hf,Zr,Ta,Ti)B2-SiC ceramic powder while increasing the bulk density. Spray granulation is used to improve the flowability of (Hf,Zr,Ta,Ti)B2-SiC ceramic powder, ensuring that the (Hf,Zr,Ta,Ti)B2-SiC ceramic coating obtained by plasma spraying technology has a high density. The results of the examples show that the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder provided by the present invention is free of impurities, has high density, and a loose packing density of 1.31 g / cm³. 3The fluidity is 58.77s / 50g, and the porosity of the (Hf,Zr,Ta,Ti)B2-SiC ceramic coating is 10.19%, indicating high density. Attached Figure Description

[0021] Figure 1 (Hf) prepared in Example 1 0.25 Zr 0.25 Ta 0.25 Ti 0.25 SEM image of B2 ceramic powder;

[0022] Figure 2 (Hf) prepared in Example 1 0.25 Zr 0.25 Ta 0.25 Ti 0.25 EDS diagram of B2 ceramic powder;

[0023] Figure 3 (Hf) prepared in Example 1 0.25 Zr 0.25 Ta 0.25 Ti 0.25 XRD pattern of B2 ceramic powder;

[0024] Figure 4 (Hf) prepared in Example 1 0.25 Zr 0.25 Ta 0.25 Ti 0.25 SEM image of the surface of B2-SiC ceramic powder;

[0025] Figure 5 (Hf) prepared in Example 1 0.25 Zr 0.25 Ta 0.25 Ti 0.25 SEM image of cross-section of B2-SiC ceramic powder;

[0026] Figure 6 (Hf) prepared in Example 1 0.25 Zr 0.25 Ta 0.25 Ti 0.25 XRD pattern of B2-SiC ceramic powder;

[0027] Figure 7 (Hf) prepared in Example 2 0.25 Zr 0.25 Ta 0.25 Ti 0.25 SEM image of the B2-SiC ceramic coating;

[0028] Figure 8 (Hf) prepared in Example 20.25 Zr 0.25 Ta 0.25 Ti 0.25 SEM image of the cross section of the B2-SiC ceramic coating;

[0029] Figure 9 (Hf) prepared for Comparative Example 1 0.25 Zr 0.25 Ta 0.25 Ti 0.25 XRD pattern of B2 ceramic powder. Detailed Implementation

[0030] This invention provides a method for preparing (Hf,Zr,Ta,Ti)B2-SiC ceramic powder, comprising the following steps:

[0031] (1) Metal oxide powder and B4C powder were ball-milled and then subjected to thermal reduction reaction to obtain (Hf,Zr,Ta,Ti)B2 ceramic powder;

[0032] (2) The (Hf,Zr,Ta,Ti)B2 ceramic powder, SiC powder and water-soluble binder obtained in step (1) are mixed and then ball-milled to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry;

[0033] (3) Spray granulation is performed on the (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry obtained in step (2) to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic powder.

[0034] This invention involves ball milling and mixing metal oxide powder and B4C powder, followed by a thermal reduction reaction to obtain (Hf,Zr,Ta,Ti)B2 ceramic powder.

[0035] In this invention, the metal oxide preferably includes HfO2 powder, ZrO2 powder, Ta2O5 powder, and TiO2 powder. By limiting the types of metal oxides, this invention allows B4C powder to directly react with HfO2 powder, ZrO2 powder, Ta2O5 powder, and TiO2 powder in a single redox reaction to generate (Hf,Zr,Ta,Ti)B2. This reduces the possibility of interdiffusion caused by the reaction of boron carbide with HfO2 powder, ZrO2 powder, Ta2O5 powder, and TiO2 powder to form corresponding borides, thus avoiding the generation of second-phase impurities due to uneven diffusion.

[0036] In this invention, the molar ratio of the metal oxide powder to the B4C powder is 3.5:(0.55-0.65), preferably 3.5:0.6. This invention, by limiting the molar ratio of the metal oxide powder to the B4C powder, allows for a more complete reaction of the metal oxide powder, forming a single-phase (Hf,Zr,Ta,Ti)B2 ceramic without impurity formation, thus improving the density of the (Hf,Zr,Ta,Ti)B2 ceramic powder.

[0037] In this invention, when the (Hf,Zr,Ta,Ti)B2 ceramic powder is (Hf 0.25 Zr 0.25 Ta 0.25 Ti 0.25 When using B2 ceramic powder, the molar ratio of HfO2 powder, ZrO2 powder, Ta2O5 powder, TiO2 powder and B4C powder is 1:1:0.5:1:(0.55~0.65).

[0038] In this invention, the particle size of the HfO2 powder, ZrO2 powder, Ta2O5 powder, TiO2 powder, and B4C powder is preferably 500–1000 nm. In embodiments of this invention, the particle size of the HfO2 powder, ZrO2 powder, Ta2O5 powder, TiO2 powder, and B4C powder may specifically be 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, or 1000 nm. This invention ensures more uniform mixing with other raw materials by limiting the particle size of the HfO2 powder, ZrO2 powder, Ta2O5 powder, TiO2 powder, and B4C powder.

[0039] In this invention, the preferred method for ball milling and mixing the metal oxide powder and B4C powder is wet ball milling. In this invention, the preferred medium for wet ball milling is anhydrous ethanol. In this invention, the preferred mass ratio of the sum of the masses of the metal oxide powder and B4C powder to the mass of anhydrous ethanol is 1:(2-3). As one embodiment of this invention, the grinding balls used in the wet ball milling can be zirconia grinding beads; the diameter of the zirconia grinding beads can be 2mm, 5mm, and 10mm; the mass ratio of the 2mm, 5mm, and 10mm zirconia grinding beads can be (1-1.5):(2-3):(1-1.5); in embodiments of this invention, the specific mass ratio of the 2mm, 5mm, and 10mm zirconia grinding beads can be 1:1.5:1, 1:2:1, or 1.5:2:1. In this invention, the ball-to-material ratio in the wet ball milling is preferably 24:(3-40); in embodiments of this invention, the ball-to-material ratio in the wet ball milling can specifically be 24:3, 24:9.6, 24:20, 24:30, or 24:40. In this invention, the rotational speed of the wet ball milling is preferably 250-400 r / min; in embodiments of this invention, the rotational speed of the wet ball milling can specifically be 250 r / min, 350 r / min, or 400 r / min. In this invention, the wet ball milling time is preferably 2-5 hours; in embodiments of this invention, the wet ball milling time can specifically be 2 hours, 3 hours, 4 hours, or 5 hours. This invention ensures a more uniform mixture of metal oxide powder and B4C powder by limiting the ball milling mixing method and parameters, which is beneficial for the more complete generation of (Hf,Zr,Ta,Ti)B2 ceramic powder.

[0040] After ball milling and mixing, the present invention preferably involves drying, crushing and drying the ball-milled product in sequence, and then carrying out a thermal reduction reaction to obtain (Hf,Zr,Ta,Ti)B2 ceramic powder.

[0041] In this invention, the drying temperature is preferably 70-80°C; in embodiments of this invention, the drying temperature may specifically be 70°C, 75°C, or 100°C. In this invention, the drying time is preferably 12-24 hours; in embodiments of this invention, the drying time may specifically be 12 hours, 15 hours, 18 hours, 20 hours, or 24 hours. This invention does not impose any particular limitation on the crushing method; any crushing method well-known in the art can be used to crush the dried mixture. In this invention, the re-drying temperature is preferably 70-80°C; in embodiments of this invention, the re-drying temperature may specifically be 70°C, 75°C, or 100°C. In this invention, the re-drying time is preferably 2-4 hours; in embodiments of this invention, the re-drying time may specifically be 2 hours, 3 hours, or 4 hours.

[0042] In this invention, the preferred reaction occurring during the thermal reduction process is HfO2 + ZrO2 + Ta2O5 + TiO2 + B4C → (Hf 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2. In this invention, the temperature of the thermal reduction reaction is preferably 1800–2000°C; in embodiments of this invention, the temperature of the thermal reduction reaction may specifically be 1800°C, 1900°C, or 2000°C. In this invention, the time of the thermal reduction reaction is preferably 1–3 hours; in embodiments of this invention, the time of the thermal reduction reaction may specifically be 1 hour, 2 hours, or 3 hours. As one implementation, the heating rate of the thermal reduction reaction may be 5–10°C / min; in embodiments of this invention, the heating rate of the thermal reduction reaction may specifically be 5°C / min, 6°C / min, 7°C / min, 8°C / min, 9°C / min, or 10°C / min. In this invention, the thermal reduction reaction is preferably carried out under an argon atmosphere. This invention ensures that the raw materials react more fully to obtain a single phase (Hf) by limiting the parameters of the thermal reduction reaction. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2 High-entropy ceramic powder.

[0043] After the thermal reduction reaction is completed, the product of the thermal reduction reaction is preferably subjected to ball milling, drying, crushing, and re-drying in sequence to obtain (Hf,Zr,Ta,Ti)B2 ceramic powder. In this invention, the ball milling media, grinding balls, and ball-to-particle ratio for ball milling the product of the thermal reduction reaction are the same as the ball milling parameters for the metal oxide powder and B4C powder described above, and will not be repeated here. In this invention, the ball milling speed for the product of the thermal reduction reaction is preferably 300–500 r / min; in the embodiments of this invention, it can be specifically 300 r / min, 400 r / min, or 500 r / min. In this invention, the ball milling time for the product of the thermal reduction reaction is preferably 5–8 h; in the embodiments of this invention, it can be specifically 5 h, 6 h, 7 h, or 8 h. In this invention, the drying, crushing, and re-drying parameters are the same as the parameters for drying, crushing, and re-drying after ball milling of the metal oxide powder and B4C powder described above, and will not be repeated here.

[0044] In this invention, the particle size of the (Hf,Zr,Ta,Ti)B2 ceramic powder is preferably less than 30 μm. This invention ensures more uniform mixing with SiC powder by limiting the particle size of the (Hf,Zr,Ta,Ti)B2 ceramic powder.

[0045] After obtaining (Hf,Zr,Ta,Ti)B2 ceramic powder, the present invention mixes the obtained (Hf,Zr,Ta,Ti)B2 ceramic powder, SiC powder and water-soluble binder and then ball-mills them to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry.

[0046] In this invention, the particle size of the SiC powder is preferably 1–3 μm. In embodiments of this invention, the particle size of the SiC powder may specifically be 1 μm, 2 μm, or 3 μm. This invention improves the density and bulk density of (Hf,Zr,Ta,Ti)B2-SiC ceramic powder by limiting the particle size of the SiC powder to more fully fill (Hf,Zr,Ta,Ti)B2.

[0047] In this invention, the preferred volume ratio of (Hf,Zr,Ta,Ti)B2 ceramic powder to SiC powder is (2.3–9):1. In embodiments of this invention, the volume ratio of (Hf,Zr,Ta,Ti)B2 ceramic powder to SiC powder can specifically be 2.3:1, 4:1, 6:1, 8:1, or 9:1. This invention, by limiting the volume ratio of (Hf,Zr,Ta,Ti)B2 ceramic powder to SiC powder, more fully fills (Hf,Zr,Ta,Ti)B2, further improving the density and bulk density of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder.

[0048] In this invention, the water-soluble binder preferably includes polyvinyl alcohol, polyurethane, polyethylene glycol, or water glass. This invention, by limiting the type of water-soluble binder, more effectively improves the bonding strength between (Hf,Zr,Ta,Ti)B2 and SiC ceramic powder.

[0049] In this invention, the preferred mass content of the water-soluble binder is 0.2% to 0.5% of the total mass of (Hf,Zr,Ta,Ti)B2 ceramic powder and SiC powder. Specifically, the mass content of the water-soluble binder can be 0.2%, 0.3%, or 0.5% of the total mass of (Hf,Zr,Ta,Ti)B2 ceramic powder and SiC powder. This invention further improves the bonding strength between (Hf,Zr,Ta,Ti)B2 and SiC ceramic powder by limiting the mass content of the water-soluble binder.

[0050] In this invention, the grinding balls, grinding rate, ball-to-material ratio, and grinding time are the same as the grinding parameters for the metal oxide powder and B4C powder described above, and will not be repeated here. In this invention, the grinding medium is preferably deionized water. In this invention, the mass ratio of the sum of the (Hf,Zr,Ta,Ti)B2 ceramic powder and SiC powder to deionized water is preferably 1:(1-2).

[0051] After obtaining the (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry, this invention performs spray granulation on the (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic powder. In this invention, the inlet temperature of the spray granulation is preferably 240–270°C. In embodiments of this invention, the inlet temperature of the spray granulation can specifically be 240°C, 250°C, 260°C, or 270°C. In this invention, the outlet temperature of the spray granulation is preferably 135–160°C. In embodiments of this invention, the outlet temperature of the spray granulation can specifically be 135°C, 145°C, 155°C, or 160°C. In this invention, the peristaltic pump speed of the spray granulation is preferably 30–50 r / min. In embodiments of this invention, the peristaltic pump speed of the spray granulation can specifically be 30 r / min, 40 r / min, or 50 r / min. In this invention, the nozzle rotation speed for spray granulation is preferably 30-50 r / min. In embodiments of this invention, the nozzle rotation speed for spray granulation can specifically be 30 r / min, 40 r / min, or 50 r / min. This invention, by limiting the parameters of spray granulation, ensures that the obtained (Hf,Zr,Ta,Ti)B2-SiC ceramic powder is closer to agglomerated spheres, further improving the flowability of (Hf,Zr,Ta,Ti)B2-SiC ceramic powder.

[0052] After spray granulation, the present invention preferably screens the resulting product to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic powder. The present invention does not specify a particular screening method; any screening method well-known in the art can be used to obtain the desired particle size.

[0053] The present invention also provides (Hf,Zr,Ta,Ti)B2-SiC ceramic powder prepared by the preparation method described in the above technical solution.

[0054] In this invention, the particle size of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder is preferably 200-400 mesh. In embodiments of this invention, the particle size of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder can specifically be 200 mesh, 250 mesh, 300 mesh, 350 mesh, or 400 mesh. This invention ensures better density of the obtained (Hf,Zr,Ta,Ti)B2-SiC ceramic coating by limiting the particle size of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder.

[0055] This invention utilizes an excess of B4C powder to ensure a more complete reaction of the metal oxide powder, forming a single-phase (Hf,Zr,Ta,Ti)B2 ceramic without impurity formation, thus improving the density of the (Hf,Zr,Ta,Ti)B2 ceramic powder. Using SiC powder as a filler phase further enhances the density and bulk density of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder. Spray granulation further improves the flowability of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder, ensuring that the resulting (Hf,Zr,Ta,Ti)B2-SiC ceramic powder, when coated using plasma spraying technology, achieves a high density of the (Hf,Zr,Ta,Ti)B2-SiC ceramic coating.

[0056] The present invention also provides a (Hf,Zr,Ta,Ti)B2-SiC ceramic coating, which is obtained by plasma spraying of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder described above.

[0057] In this invention, the plasma spraying preferably includes atmospheric plasma spraying, low-pressure plasma spraying, vacuum plasma spraying, or supersonic flame plasma spraying.

[0058] In this invention, the thickness of the (Hf,Zr,Ta,Ti)B2-SiC ceramic coating is preferably 100–300 μm. In embodiments of this invention, the thickness of the (Hf,Zr,Ta,Ti)B2-SiC ceramic coating can specifically be 100 μm, 200 μm, or 300 μm. This invention ensures greater stability and prevents cracking during the oxidation and ablation process by limiting the thickness of the (Hf,Zr,Ta,Ti)B2-SiC ceramic coating.

[0059] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0060] Example 1

[0061] A type of (Hf) 0.25 Zr 0.25 ,Ta 0.25 Ti 0.25 The preparation method of B2-SiC ceramic powder consists of the following steps:

[0062] (1) HfO2 powder, ZrO2 powder, Ta2O5 powder, TiO2 powder and B4C powder with a particle size of 500nm were wet ball-milled and dried in an oven at 80℃ for 24h. After being crushed in a mortar, they were dried in an oven at 80℃ for another 4h. Then, they were placed in a cylindrical graphite mold lined with graphite paper and placed in a graphite high-temperature reactor. The mixture was subjected to a thermal reduction reaction at 2000℃ for 2h under an argon atmosphere with a heating rate of 8℃ / min. After a second ball milling, the mixture was dried in an oven at 80℃ for 24h. After being crushed in a mortar, it was dried in an oven at 80℃ for another 4h to obtain HfO2 powder with a particle size of less than 30μm. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2 ceramic powder; the molar ratio of HfO2 powder, ZrO2 powder, Ta2O5 powder, TiO2 powder and B4C powder is 1:1:0.5:1:0.6; the ball milling medium is anhydrous ethanol; the mass ratio of the sum of the metal oxide powder and B4C powder to anhydrous ethanol is 1:2.5; the grinding balls are zirconia grinding beads; the diameters of the zirconia grinding beads are 2mm, 5mm and 10mm; the 2mm, 5mm and 10mm diameters... The mass ratio of zirconium oxide grinding beads is 1:2:1; the ball-to-material ratio is 24:9.6; the grinding speed is 350 r / min; the grinding time is 4 h; the grinding media, grinding balls, and ball-to-material ratio for grinding the product of the thermal reduction reaction are the same as the grinding parameters for the metal oxide powder and B4C powder mentioned above; the grinding speed for the product of the thermal reduction reaction is 500 r / min; the grinding time for the product of the thermal reduction reaction is 8 h.

[0063] (2) The (Hf) obtained in step (1) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2 ceramic powder, SiC powder with a particle size of 1-3 μm, and polyvinyl alcohol binder were mixed and ball-milled to obtain (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2-SiC ceramic slurry; the (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The volume ratio of B2 ceramic powder to SiC powder is 4:1; the mass content of the polyvinyl alcohol binder is 0.5% of the total mass of (Hf, Zr, Ta, Ti)B2 ceramic powder and SiC powder; the grinding balls, grinding rate, ball-to-material ratio, and grinding time of the ball mill are the same as the ball milling parameters for the metal oxide powder and B4C powder mentioned above; the grinding medium is deionized water; the (Hf... 0.25Zr 0.25 Ta 0.25 Ti 0.25 The mass ratio of the sum of B2 ceramic powder and SiC powder to deionized water is 1:1.5.

[0064] (3) The (Hf) obtained in step (2) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2-SiC ceramic slurry was spray-granulated and then sieved through a 200-400 mesh standard sieve to obtain (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2-SiC ceramic powder; the inlet temperature of the spray granulation is 250℃; the outlet temperature of the spray granulation is 150℃; the peristaltic pump speed of the spray granulation is 40r / min; the nozzle speed of the spray granulation is 45r / min.

[0065] Example 2

[0066] A type of (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2-SiC ceramic coating, using the method described in Example 1 (Hf 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2-SiC ceramic powder was obtained by atmospheric plasma spraying; the parameters of the atmospheric plasma spraying were as follows: current 1000A; main gas Ar, main gas flow rate 60SCFH; auxiliary gas H2, auxiliary gas flow rate 20SCFH; carrier gas Ar, carrier gas flow rate 3SCFH; distance between the spray gun and the substrate 90mm; powder feed rate 20r / min; power 40kW; the (Hf 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The thickness of the B2-SiC ceramic coating is 200μm.

[0067] Comparative Example 1

[0068] The only difference between this comparative example and Example 1 is that B4C powder is replaced with B powder and step (2) is omitted. The rest is the same as Example 1.

[0069] Using a Hall effect flow meter for Example 1 (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25The bulk density and flowability of B2-SiC ceramic powder were tested, as shown in Table 1.

[0070] Table 1 Example 1 (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 Table of Bulk Density and Flowability of B2-SiC Ceramic Powder

[0071] <![CDATA[Bulk density (g / cm 3 )]]> 1.31 Flowability (s / 50g) 58.77

[0072] As shown in Table 1: Example 1 (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The bulk density and flowability of B2-SiC ceramic powder are 1.31 g / cm³. 3 With a strength of 58.77s / 50g, it meets the requirements for plasma spraying.

[0073] The (Hf) prepared in Example 1 was examined using a scanning electron microscope. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The morphology of B2 ceramic powder was characterized, such as... Figure 1 As shown in the figure. It can be seen from the figure that in Example 1 (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2 ceramic powder has a particle size of less than 30μm.

[0074] The Hf sample obtained in Example 1 was analyzed using an energy dispersive spectrometer. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The B2 ceramic powder was analyzed, and the results are as follows: Figure 2 As shown, from left to right, they are (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 Image of B2 ceramic powder and distribution diagram of each element. From the image, we can see that: (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The four metal elements and boron are evenly distributed in the B2 ceramic powder.

[0075] The (Hf) prepared in Example 1 was analyzed using an X-ray diffractometer. 0.25 Zr 0.25 Ta 0.25 Ti 0.25The phase composition of B2 ceramic powder was analyzed, and the results are as follows: Figure 3 As shown in the figure. From the figure, we can see that: (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The diffraction peaks of the B2 ceramic powder exhibit highly crystalline single-phase diffraction characteristics, with no residual oxides or amorphous boron carbide, indicating the formation of a single phase (Hf). 0.25 Zr 0.25 Ta 0.25 Ti 0.25 )B2.

[0076] The (Hf) obtained in Example 1 was examined using a scanning electron microscope. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The surface morphology of B2-SiC ceramic powder was characterized, such as... Figure 4 As shown in the figure. From the figure, we can see that: (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2B2-SiC ceramic powder has a rough surface and high sphericity.

[0077] The (Hf) obtained in Example 1 was examined using a scanning electron microscope. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The cross-sectional morphology of B2-SiC ceramic powder was characterized, such as... Figure 5 As shown in the figure. From the figure, we can see that: (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 B2-SiC ceramic powder is composed of (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 It is made by bonding B2 ceramic powder and SiC powder.

[0078] The (Hf) prepared in Example 1 was analyzed using an X-ray diffractometer. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The phase composition of B2-SiC ceramic powder was analyzed, and the results are as follows: Figure 6 As shown in the figure. It can be seen from the figure that only (Hf) exists. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The diffraction peaks of B2 and SiC indicate that no impurities were introduced.

[0079] The (Hf) obtained in Example 2 was examined using a scanning electron microscope. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The surface morphology of the B2-SiC ceramic coating was characterized, such as... Figure 7 As shown in the figure. From the figure, we can see that: (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The B2-SiC ceramic coating is fully melted and spread, resulting in high density.

[0080] The (Hf) obtained in Example 2 was examined using a scanning electron microscope. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The cross-sectional morphology of the B2-SiC ceramic coating was characterized, such as... Figure 8 As shown in the figure. From the figure, we can see that: (Hf) 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The thickness of the B2-SiC ceramic coating can reach 200μm, and the coating density is high.

[0081] The (Hf) sample prepared in Comparative Example 1 was analyzed using an X-ray diffractometer. 0.25 Zr 0.25 Ta 0.25 Ti 0.25 The phase composition of B2 ceramic powder was analyzed, and the results are as follows: Figure 9 As shown in the figure, there are low side peaks next to the three strong peaks, indicating the presence of a second-phase impurity. Comparison with the material standard PDF card confirms that the second impurity is undissolved HfB2.

[0082] In summary, the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder provided by this invention is free of impurities, has high density, and good bulk density and flowability. The (Hf,Zr,Ta,Ti)B2-SiC ceramic coating obtained by plasma spraying has high density.

[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing (Hf,Zr,Ta,Ti)B2-SiC ceramic powder, comprising the following steps: (1) The metal oxide powder and B4C powder are ball-milled and then subjected to thermal reduction reaction to obtain (Hf,Zr,Ta,Ti)B2 ceramic powder; the metal oxide powder includes HfO2 powder, ZrO2 powder, Ta2O5 powder and TiO2 powder; the molar ratio of the metal oxide powder to B4C powder is 3.5:(0.55~0.65); (2) The (Hf,Zr,Ta,Ti)B2 ceramic powder, SiC powder and water-soluble binder obtained in step (1) are mixed and ball-milled to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry; (3) Spray granulation is performed on the (Hf,Zr,Ta,Ti)B2-SiC ceramic slurry obtained in step (2) to obtain (Hf,Zr,Ta,Ti)B2-SiC ceramic powder.

2. The preparation method according to claim 1, characterized in that, The temperature of the thermal reduction reaction in step (1) is 1800~2000℃, and the time of the thermal reduction reaction is 1~3h.

3. The preparation method according to claim 1, characterized in that, In step (2), the volume ratio of (Hf,Zr,Ta,Ti)B2 ceramic powder to SiC powder is (2.3~9):

1.

4. The preparation method according to claim 1 or 3, characterized in that, The particle size of the SiC powder in step (2) is 1~3μm.

5. The preparation method according to claim 1, characterized in that, In step (2), the mass content of the water-soluble binder is 0.2-0.5% of the total mass of (Hf,Zr,Ta,Ti)B2 ceramic powder and SiC powder.

6. The preparation method according to claim 1 or 5, characterized in that, The water-soluble binder in step (2) includes polyvinyl alcohol, polyethylene glycol, or water glass.

7. The preparation method according to claim 1, characterized in that, In step (3), the inlet temperature of spray granulation is 240~270℃, the outlet temperature of spray granulation is 135~160℃, the peristaltic pump speed of spray granulation is 30~50r / min, and the nozzle speed of spray granulation is 30~50r / min.

8. (Hf,Zr,Ta,Ti)B2-SiC ceramic powder prepared by the preparation method according to any one of claims 1 to 7.

9. The (Hf,Zr,Ta,Ti)B2-SiC ceramic powder according to claim 8, characterized in that, The particle size of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder is 200~400 mesh.

10. A (Hf,Zr,Ta,Ti)B2-SiC ceramic coating, obtained by plasma spraying of the (Hf,Zr,Ta,Ti)B2-SiC ceramic powder as described in claim 8 or 9.

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