Composite ceramic material and preparation method thereof, and preparation method of composite ceramic coating

Abstract

The invention relates to the technical field of ceramic coatings, in particular to a composite ceramic material and a preparation method thereof, and a preparation method of a composite ceramic coating. The invention provides a preparation method of a composite ceramic material, which comprises the following steps: mixing hexagonal boron nitride, an organic adhesive and aluminum oxide to obtain a mixture; sequentially performing spray drying and sintering on the mixture to obtain the composite ceramic material. The composite ceramic material prepared by the preparation method retains excellent wear resistance, corrosion resistance and insulativity of an aluminum oxide ceramic coating, is endowed with excellent self-lubricating performance and thermal stability, and has excellent comprehensive performance.

Description

Technical Field

[0001] The present invention relates to the technical field of ceramic coatings, and in particular to a composite ceramic material and a preparation method thereof, and a preparation method of a composite ceramic coating. Background Art

[0002] Plasma-sprayed Al2O3 ceramic coatings are often deposited on metal mechanical parts to enhance their protective properties due to their excellent physical and chemical properties. However, Al2O3 ceramic coatings have poor lubricity, with a coefficient of friction typically ranging from 0.6 to 0.8 at room temperature. To improve the tribological properties of these coatings, lubricating powders, such as molybdenum sulfide and graphite, are often added to the coating. However, the extremely high temperatures of atmospheric plasma spraying make it difficult for molybdenum sulfide and graphite to remain stable in the flame plume. In contrast, h-BN has a lamellar structure, and weak van der Waals forces between the layers facilitate shearing along the sliding direction, resulting in excellent self-lubricating properties. Furthermore, h-BN's high thermal conductivity and excellent thermal stability improve the melting efficiency of plasma-sprayed powders while preventing structural degradation or oxidation during passage through the high-temperature plasma plume. Therefore, h-BN is considered a promising reinforcement for plasma-sprayed composites.

[0003] However, the alumina-hexagonal boron nitride powder mechanically mixed by physical means is very severely agglomerated due to the inherent van der Waals force of h-BN, which becomes a gathering place for crack nucleation and deteriorates the mechanical and tribological properties of the composite material. Studies have shown that compared with the aggregation of h-BN in composite materials, uniform dispersion can greatly improve the bending strength, fracture toughness, relative density, hardness and elastic modulus of the material. Therefore, whether h-BN can be evenly distributed in the composite material is the key to its performance improvement. In the prior art, h-BN is successfully introduced uniformly into the composite material by using Ni to coat h-BN, but the disadvantages are poor wettability between metal and ceramic, increased internal defects in the coating, and the introduction of the metal phase seriously reduces the overall performance of the coating. Summary of the Invention

[0004] In view of this, the present invention aims to provide a composite ceramic material, a preparation method thereof, and a preparation method for a composite ceramic coating. The composite ceramic material prepared by the preparation method retains the excellent wear resistance, corrosion resistance, and insulation properties of the alumina ceramic coating while also imparting excellent self-lubricating properties and thermal stability, resulting in excellent overall performance.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a composite ceramic material, comprising the following steps:

[0007] mixing hexagonal boron nitride, an organic binder, and aluminum oxide to obtain a mixture;

[0008] The mixed material is spray-dried and sintered in sequence to obtain the composite ceramic material.

[0009] Preferably, the mass percentage of hexagonal boron nitride in the mixture is 10% to 20%;

[0010] The mass percentage of the organic binder in the mixture is 1% to 2%.

[0011] Preferably, the spray drying process comprises:

[0012] The mixed material is heated and flows into the atomizing nozzle. The mixed material falling into the atomizing area is impacted and crushed by the inert gas through the atomizing nozzle, and then cooled and solidified.

[0013] Preferably, the heating temperature is 150-300°C;

[0014] The pressure of the inert gas is 0.3-0.5 MPa, and the flow rate is 10-30 m 3 / h;

[0015] The inert gas includes argon or helium.

[0016] Preferably, the sintering temperature is 1000-1200° C. and the sintering time is 24 hours.

[0017] The present invention also provides a composite ceramic material prepared by the preparation method described in the above technical solution, comprising an α-Al2O3 phase, an Al5BO9 phase and an h-BN phase.

[0018] Preferably, the composite ceramic material is a spherical structure with a porous surface.

[0019] Preferably, the particle size of the composite ceramic material is 30 to 90 μm.

[0020] The present invention also provides a method for preparing a composite ceramic coating, comprising the following steps:

[0021] Adopting atmospheric plasma spraying technology to spray and deposit the composite ceramic material on the surface of the metal substrate to obtain the composite ceramic coating;

[0022] The composite ceramic material is the composite ceramic material described in the above technical solution.

[0023] Preferably, the ionized gas used in the atmospheric plasma spraying is argon, and the auxiliary gas is hydrogen;

[0024] The thickness of the composite ceramic coating is 200-500 μm.

[0025] The present invention provides a method for preparing a composite ceramic material, comprising the following steps: mixing hexagonal boron nitride, an organic binder, and aluminum oxide to obtain a mixture; spray drying and sintering the mixture in sequence to obtain the composite ceramic material. The preparation method of the present invention utilizes spray drying to avoid aggregation of boron nitride, thereby uniformly distributing the boron nitride, thereby preparing a uniformly distributed spherical composite ceramic material and ensuring the integrity of the material; sintering is employed to remove the organic binder and oxidize the hexagonal boron nitride, generating a large amount of boron oxide and gas, which further react to generate Al5BO9; specifically, 4BN+3O2→2B2O3+2N2; 2Al2O 3+ B2O3→Al4B2O9; 5Al2O3+B2O3→2Al5BO9; so that the final prepared composite ceramic material includes α-Al2O3 phase, Al5BO9 phase and h-BN phase. And because gas (N2) is generated during the preparation process, the surface of the composite ceramic material can present a porous structure. The α-Al2O3 phase in the composite ceramic material has excellent wear resistance, the Al5BO9 phase has excellent thermal stability, and the h-BN phase has excellent solid lubrication performance. Therefore, the composite ceramic material including the three phases of α-Al2O3 phase, Al5BO9 phase and h-BN phase can retain the excellent wear resistance, corrosion resistance and insulation of the alumina ceramic coating while giving it self-lubricating properties and better thermal stability, which can more effectively improve the service conditions under extreme working conditions. Therefore, the composite ceramic coating prepared using the composite ceramic material of the present invention can have good protective capabilities and application prospects on the surface of wear parts. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a SEM image of the composite ceramic material described in Example 1;

[0027] Figure 2 This is a SEM image of the surface of the composite ceramic coating described in Example 1;

[0028] Figure 3 This is a SEM image of the longitudinal section of the composite ceramic coating described in Example 1;

[0029] Figure 4 The XRD patterns of the composite ceramic material and the composite ceramic coating described in Example 1;

[0030] Figure 5 The friction coefficients of the composite ceramic coating described in Example 1 and the alumina ceramic coating described in Comparative Example 1 for different friction pairs. DETAILED DESCRIPTION

[0031] The present invention provides a method for preparing a composite ceramic material, comprising the following steps:

[0032] mixing hexagonal boron nitride, an organic binder, and aluminum oxide to obtain a mixture;

[0033] The mixed material is spray-dried and sintered in sequence to obtain the composite ceramic material.

[0034] In the present invention, unless otherwise specified, all preparation raw materials are commercially available products well known to those skilled in the art.

[0035] The invention mixes hexagonal boron nitride, an organic binder and aluminum oxide to obtain a mixture.

[0036] In the present invention, the purity of the hexagonal boron nitride is preferably ≥99.9 wt %, and the purity of the aluminum oxide is preferably ≥99.9 wt %.

[0037] In the present invention, the organic binder preferably includes one or more of polyvinyl alcohol, polyethylene glycol, and carboxymethyl cellulose. When the organic binder includes two or more of the above-mentioned specific selections, the present invention does not have any particular restrictions on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In an embodiment of the present invention, the organic binder can be polyvinyl alcohol.

[0038] In the present invention, the mixing preferably includes stirring and ball milling performed sequentially; the stirring speed is preferably 200-1000 rpm, more preferably 600 rpm; the stirring time is preferably 6-10 h, more preferably 8 h; the ball milling speed is preferably 200-400 rpm, more preferably 400 rpm; the ball milling time is preferably 18-32 h, more preferably 24 h.

[0039] In the present invention, the mass percentage of hexagonal boron nitride in the mixture is preferably 10% to 20%, more preferably 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19% or 20%. In an embodiment of the present invention, the mass percentage of hexagonal boron nitride in the mixture can be 10%, 15% or 20%.

[0040] In the present invention, the mass percentage of the organic binder in the mixture is preferably 1% to 2%, more preferably 1%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9% or 2%. In an embodiment of the present invention, the mass percentage of the organic binder in the mixture can be 1%.

[0041] In the present invention, the purpose of controlling the dosage relationship of the hexagonal boron nitride, organic binder and aluminum oxide is to exert the synergistic effect of lubrication and wear resistance of hexagonal boron nitride and aluminum oxide on the basis of maintaining the bonding performance of the continuous phase of the organic binder, so as to enhance the friction reduction and wear resistance of the coating and obtain a uniform slurry.

[0042] After obtaining the mixture, the present invention sequentially spray-dries and sinters the mixture to obtain the composite ceramic material.

[0043] In the present invention, the spray drying process preferably includes:

[0044] The mixed material is heated and flows into the atomizing nozzle. The mixed material falling into the atomizing area is impacted and crushed by the inert gas through the atomizing nozzle, and then cooled and solidified.

[0045] In the present invention, the heating temperature is preferably 150-300°C, more preferably 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C or 300°C. In an embodiment of the present invention, the heating temperature may be 200°C. The present invention does not have any particular limitation on the heating time, and a time well known to those skilled in the art can be used to ensure that the slurry obtained after the heating maintains good fluidity and can flow smoothly into the atomizing nozzle.

[0046] In the present invention, the rate at which the slurry obtained after heating flows into the atomizing nozzle is preferably 10 to 100 mL / min, more preferably 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min or 100 mL / min. In an embodiment of the present invention, the rate at which the slurry obtained after heating flows into the atomizing nozzle may be 50 mL / min.

[0047] In the present invention, the inert gas preferably includes argon or helium. In an embodiment of the present invention, the inert gas may be argon.

[0048] In the present invention, the pressure of the inert gas is preferably 0.3-0.5 MPa, more preferably 0.3 MPa, 0.35 MPa, 0.4 MPa, 0.45 MPa or 0.5 MPa. In an embodiment of the present invention, the pressure of the inert gas may be 0.4 MPa.

[0049] In the present invention, the flow rate of the inert gas is preferably 10 to 30 m 3 / h, more preferably 10m 3 / h、12m 3 / h、14m3 / h、16m 3 / h、18m 3 / h、20m 3 / h、22m 3 / h、24m 3 / h、26m 3 / h、28m 3 / h or 30m 3 / h. In an embodiment of the present invention, the flow rate of the inert gas can be 30m 3 / h.

[0050] The present invention does not have any special limitation on the cooling and solidification process, and the process well known to those skilled in the art can be used.

[0051] In the present invention, the spray drying process is used to prepare uniform spherical composite ceramic materials.

[0052] In the present invention, the sintering temperature is preferably 1000-1200° C., more preferably 1020° C., 1040° C., 1060° C., 1080° C., 1100° C., 1120° C., 1140° C., 1160° C., 1180° C. or 1200° C. In an embodiment of the present invention, the sintering temperature may be 1200° C.

[0053] In the present invention, the sintering time is preferably 24 hours.

[0054] In an embodiment of the present invention, the sintering is performed in a muffle furnace.

[0055] The present invention provides a composite ceramic material prepared by the preparation method described in the above technical solution, comprising an α-Al2O3 phase, an Al5BO9 phase and an h-BN phase.

[0056] In the present invention, the composite ceramic material is preferably a spherical structure with a porous surface.

[0057] In the present invention, the particle size of the composite ceramic material is preferably 30 to 90 μm. In an embodiment of the present invention, the particle size of the composite ceramic material may be 30 to 50 μm.

[0058] The present invention also provides a method for preparing a composite ceramic coating, comprising the following steps:

[0059] Adopting atmospheric plasma spraying technology to spray and deposit the composite ceramic material on the surface of the metal substrate to obtain the composite ceramic coating;

[0060] The composite ceramic material is the composite ceramic material described in the above technical solution or the composite ceramic material prepared by the preparation method described in the above technical solution.

[0061] Before the spray deposition, the present invention also preferably includes performing a sandblasting roughening treatment on the metal substrate. The present invention does not have any special limitation on the process of the sandblasting roughening treatment, and the process can be performed using a process well known to those skilled in the art.

[0062] In the present invention, the material of the metal substrate is preferably 316L stainless steel.

[0063] In the present invention, the ionized gas used in the atmospheric plasma spraying is preferably argon, and the auxiliary gas is preferably hydrogen.

[0064] In the present invention, the thickness of the composite ceramic coating is preferably 200-500 μm. In an embodiment of the present invention, the thickness of the composite ceramic coating may be 350 μm.

[0065] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0066] Example 1

[0067] According to the mass ratio of 10:1:89, hexagonal boron nitride with a purity of ≥99.9wt%, an organic binder (type is polyvinyl alcohol) and alumina with a purity of ≥99.9wt% were mixed and stirred (the stirring speed was 600rpm, the time was 8h) and ball milled (the ball milling speed was 400rpm, the time was 24h), and then heated at 200°C to a slurry with good fluidity. The slurry was then flowed into an atomizing nozzle (the flow rate was 50mL / min) with a pressure of 0.4MPa and a flow rate of 30m 3 / h argon gas impacts and breaks the slurry falling into the atomization zone through the atomizing nozzle, so that the atomized slurry forms fine droplets, which are then cooled and solidified in the atomization chamber to form spherical agglomerated Al5BO9 / Al2O3 / BN powder particles with a particle size of 30-50μm;

[0068] The spherical agglomerated Al5BO9 / Al2O3 / BN powder particles were placed in a muffle furnace for sintering (temperature of 1200°C for 24 hours) to obtain a composite ceramic material;

[0069] Using atmospheric plasma spraying technology (ionized gas: argon, auxiliary gas: hydrogen, condition parameters: argon 50 L / min, hydrogen 9 L / min), the composite ceramic material was sprayed on the surface of a sandblasted roughened metal substrate (material: 316L stainless steel) to obtain a composite ceramic coating (thickness: 350 μm; the hardness of the composite ceramic coating is 6.6 GPa, and the interlayer bonding strength is 44.1 MPa);

[0070] The friction coefficients of the composite ceramic coating under different loads and different friction pairs are shown in Table 1:

[0071] Table 1 Friction coefficients of the composite ceramic coatings under different loads and friction pairs

[0072]

[0073] Example 2

[0074] According to the mass ratio of 15:1:84, hexagonal boron nitride with a purity of ≥99.9wt%, an organic binder (type is polyvinyl alcohol) and alumina with a purity of ≥99.9wt% were mixed and stirred (the stirring speed was 600rpm, the time was 8h) and ball milled (the ball milling speed was 400rpm, the time was 24h), and then heated at 200°C to a slurry with good fluidity. The slurry was then flowed into an atomizing nozzle (the flow rate was 50mL / min) with a pressure of 0.4MPa and a flow rate of 30m 3 / h argon gas impacts and breaks the slurry falling into the atomization zone through the atomizing nozzle, so that the atomized slurry forms fine droplets, which are then cooled and solidified in the atomization chamber to form spherical agglomerated Al5BO9 / Al2O3 / BN powder particles with a particle size of 30-50μm;

[0075] The spherical agglomerated Al5BO9 / Al2O3 / BN powder particles were placed in a muffle furnace for sintering (temperature of 1200°C for 24 hours) to obtain a composite ceramic material;

[0076] Using atmospheric plasma spraying technology (ionized gas: argon, auxiliary gas: hydrogen, condition parameters: argon 50 L / min, hydrogen 9 L / min), the composite ceramic material was sprayed on the surface of a sandblasted roughened metal substrate (material: 316L stainless steel) to obtain a composite ceramic coating (thickness: 350 μm; the hardness of the composite ceramic coating is 6.5 GPa, and the interlayer bonding strength is 35.8 MPa);

[0077] The friction coefficients of the composite ceramic coating under different loads and different friction pairs are shown in Table 2:

[0078] Table 2 Friction coefficients of the composite ceramic coatings under different loads and friction pairs

[0079]

[0080] Example 3

[0081] According to the mass ratio of 20:1:79, hexagonal boron nitride with a purity of ≥99.9wt%, an organic binder (type is polyvinyl alcohol) and alumina with a purity of ≥99.9wt% were mixed and stirred (the stirring speed was 600rpm, the time was 8h) and ball milled (the ball milling speed was 400rpm, the time was 24h), and then heated at 200°C to a slurry with good fluidity. The slurry was then flowed into an atomizing nozzle (the flow rate was 50mL / min) with a pressure of 0.4MPa and a flow rate of 30m 3 / h argon gas impacts and breaks the slurry falling into the atomization zone through the atomizing nozzle, so that the atomized slurry forms fine droplets, which are then cooled and solidified in the atomization chamber to form spherical agglomerated Al5BO9 / Al2O3 / BN powder particles with a particle size of 30-50μm;

[0082] The spherical agglomerated Al5BO9 / Al2O3 / BN powder particles were placed in a muffle furnace for sintering (temperature of 1200°C for 24 hours) to obtain a composite ceramic material;

[0083] Using atmospheric plasma spraying technology (ionized gas: argon, auxiliary gas: hydrogen, condition parameters: argon 50 L / min, hydrogen 9 L / min), the composite ceramic material was sprayed on the surface of a sandblasted roughened metal substrate (material: 316L stainless steel) to obtain a composite ceramic coating (thickness: 350 μm; the hardness of the composite ceramic coating is 6.2 GPa, and the interlayer bonding strength is 33.2 MPa);

[0084] The friction coefficients of the composite ceramic coating under different loads and different friction pairs are shown in Table 3:

[0085] Table 3 Friction coefficients of the composite ceramic coatings under different loads and friction pairs

[0086]

[0087]

[0088] Figure 1 is the SEM image of the sintered composite ceramic material described in Example 1. Figure 1It can be seen that the sphericity of the composite ceramic material is intact. During the sintering process, hexagonal boron nitride is oxidized to produce a large amount of boron oxide and gas (nitrogen). As the temperature increases, the boron oxide reacts with aluminum oxide to form Al5BO9. During the entire chemical reaction process, the aluminum oxide phase is always in an excess state. Therefore, there is no excess boron oxide phase in the final product, and it is a three-phase mixture of Al5BO9 / Al2O3 / BN. In addition, due to the generation of gas during the preparation process, the surface of the product will have a porous structure, and the increase in specific surface area can improve its melting degree.

[0089] Figure 2 This is the SEM image of the surface of the composite ceramic coating described in Example 1. Figure 3 This is the SEM image of the longitudinal section of the composite ceramic coating described in Example 1. Figure 2 and Figure 3 It can be seen that the surface of the composite ceramic coating is in a good melting state, showing a pancake shape, and the coating is relatively dense. The coating thickness is about 350 μm, and the interface with the metal substrate is very tightly bonded. This indicates that the porous structure and the high thermal conductivity of hexagonal boron nitride increase the melting degree of the composite ceramic coating.

[0090] Figure 4 The XRD patterns of the composite ceramic material and the composite ceramic coating described in Example 1 are as follows: Figure 4 It can be seen that due to its excellent thermal stability, the Al5BO9 in the composite ceramic material does not undergo phase change in the high-temperature plasma flame flow of atmospheric plasma spraying. The composite ceramic coating still contains a large amount of Al5BO9 phase, and the hard phase α-Al2O3 phase is also well preserved.

[0091] Comparative Example 1

[0092] Atmospheric plasma spraying technology (ionized gas is argon, auxiliary gas is hydrogen, condition parameters are argon 50L / min, hydrogen 9L / min), alumina is sprayed on the surface of the metal substrate (material is 316L stainless steel) after sandblasting roughening to obtain an alumina ceramic coating.

[0093] The porosity of the composite ceramic coatings of Examples 1, 2, and 3 and the alumina ceramic coating of Comparative Example 1 (based on the longitudinal cross-sectional morphology using Image Pro software was used for calculation) and the interlayer bonding strength of the coating (the test process was as follows: a NiCrAlY metal bonding layer with a thickness of about 50 μm was deposited on a sandblasted 316L metal substrate to avoid excessive residual stress between the ceramic coating and the substrate, and then the composite ceramic coatings described in Examples 1 to 3 or the alumina ceramic coating described in Comparative Example 1 were prepared. Then, E-7 epoxy resin high-temperature structural adhesive was evenly applied to the surface of the coating, and a weight (5 kg / piece) was placed on it and placed in a muffle furnace. After heating to 120° C. (3° C. / min), the temperature was kept for 3 hours, and the coating was cooled to room temperature. A microcomputer-controlled electronic universal testing machine (LE3504-H500, China) was used for comparison. The porosity of the composite ceramic coating described in Example 1 was 6.4%, which was significantly lower than the porosity of 7.1% of the alumina ceramic coating described in Comparative Example 1; the interlayer bonding strength of the composite ceramic coating described in Example 1 was 44.1 MPa, which was increased by 23.8% compared with the interlayer bonding strength of the alumina ceramic coating described in Comparative Example 1;

[0094] Dry friction tests were conducted on the composite ceramic coatings described in Examples 1, 2, and 3 and the alumina ceramic coating described in Comparative Example 1 using a CSM friction tester in reciprocating friction mode. The friction conditions were: room temperature, relative humidity of 20±5%, a linear velocity of 10 cm / s, an amplitude of 2.5 mm, loads of 3 N, 5 N, and 8 N, respectively, over a total sliding distance of 150 m. The friction partners were 316L stainless steel balls, Si3N4 balls, and WC balls (all 6 mm in diameter). Prior to the friction tests, the composite ceramic coatings described in Examples 1, 2, and 3 and the alumina ceramic coating described in Comparative Example 1 were mechanically ground and polished to a surface roughness of Ra ≈ 0.2 μm. Figure 5 The friction coefficients of the composite ceramic coating described in Example 1 and the alumina ceramic coating described in Comparative Example 1 for different friction pairs are as follows: Figure 5 It can be seen that under the same friction conditions, the friction coefficient of the composite ceramic coating described in Example 1 is much smaller than that of the alumina ceramic coating described in Comparative Example 1. This is because the transverse shear stress during the sliding process destroys the interlayer van der Waals bonds of the h-BN particles, and the h-BN forms a lubricating film on the contact surface, preventing the coating from directly contacting the friction pair. In addition, the high thermal stability of h-BN is also beneficial to improving the coating and reducing surface damage caused by frictional heat. And h-BN can also improve the tribological properties of the coating due to its excellent thermal conductivity. During the friction process, if the thermal conductivity of the material is poor, thermal softening will easily occur due to flash temperature. Therefore, since the instantaneous actual contact area is attributed to adhesive friction in a short time, the high thermal conductivity of h-BN will alleviate the material softening phenomenon caused by the accumulation of frictional heat, thereby enhancing the tribological properties of the ceramic coating.

[0095] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation thereto. It should be noted that those skilled in the art may make various improvements and modifications without departing from the principles of the present invention, and such improvements and modifications shall also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a composite ceramic material, characterized in that: The following steps are involved: mixing hexagonal boron nitride, an organic binder, and aluminum oxide to obtain a mixture; The mixed material is spray-dried and sintered in sequence to obtain the composite ceramic material.

2. The preparation method according to claim 1, wherein The mass percentage of hexagonal boron nitride in the mixture is 10% to 20%; The mass percentage of the organic binder in the mixture is 1% to 2%.

3. The preparation method according to claim 1, wherein The spray drying process includes: The mixed material is heated and flows into the atomizing nozzle. The mixed material falling into the atomizing area is impacted and crushed by the inert gas through the atomizing nozzle, and then cooled and solidified.

4. The preparation method according to claim 3, wherein The heating temperature is 150-300° C. The pressure of the inert gas is 0.3-0.5 MPa, and the flow rate is 10-30 m 3 / h; The inert gas includes argon or helium.

5. The preparation method according to claim 1, wherein The sintering temperature is 1000-1200° C. and the sintering time is 24 hours.

6. The composite ceramic material prepared by the preparation method according to any one of claims 1 to 5, characterized in that: Including α-Al2O3 phase, Al5BO9 phase and h-BN phase.

7. The composite ceramic material according to claim 6, wherein The composite ceramic material is a spherical structure with a porous surface.

8. The composite ceramic material according to claim 6 or 7, characterized in that: The particle size of the composite ceramic material is 30 to 90 μm.

9. A method for preparing a composite ceramic coating, characterized in that: The following steps are involved: Adopting atmospheric plasma spraying technology to spray and deposit the composite ceramic material on the surface of the metal substrate to obtain the composite ceramic coating; The composite ceramic material is the composite ceramic material according to any one of claims 6 to 8.

10. The preparation method according to claim 9, wherein The ionized gas used in the atmospheric plasma spraying is argon, and the auxiliary gas is hydrogen; The thickness of the composite ceramic coating is 200-500 μm.

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