Powder coating, preparation method thereof, coating and application of coating

Abstract

The invention belongs to the technical field of high-temperature-resistant coatings, and particularly relates to a powder coating, a preparation method thereof and a coating. The powder coating provided by the invention is prepared from the following components in percentage by volume: 62.4 to 73.8 percent of ZrB2, 8.8 to 10.6 percent of SiC, 8.8 to 10.6 percent of MoSi2 and 5 to 20 percent of Gd2O3, the volume is a loose filling volume. A coating layer formed by the powder coating provided by the invention has good infrared emissivity and heat conduction capability, the service temperature of the coating layer can be reduced, the ablation behavior of the coating layer can be delayed, and meanwhile, the oxidation ablation resistance of the coating layer can also be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of high-temperature resistant coatings, and in particular relates to a powder coating and a preparation method thereof, a coating and applications thereof. Background Art

[0002] Hypersonic vehicles, with their advantages of high speed and strong penetration capabilities, have become a key research topic. However, hypersonic vehicles are subject to severe aerodynamic heating during service, and key components made of carbon / carbon composites are highly susceptible to failure due to ablation. Preparing an oxidation-resistant ablative coating on the surface of carbon / carbon composites is an effective approach to address this problem.

[0003] Among numerous coating material systems, ZrB2-SiC composite coatings have attracted widespread attention due to their excellent performance. However, when conventional ZrB2 / SiC coatings are exposed to temperatures above 1800°C, the SiO2 generated within the coating undergoes significant volatilization, increasing the coating's porosity and accelerating the oxygen diffusion rate. This, in turn, reduces the coating's resistance to oxidation and ablation, thus limiting its usability. Summary of the Invention

[0004] In view of this, the present invention provides a powder coating, a preparation method thereof, a coating and an application thereof. The coating formed by the powder coating provided by the present invention has good anti-oxidation and ablation properties. Applying it to the surface of a hypersonic aircraft can ensure its performance and extend its service life.

[0005] In order to solve the above technical problems, the present invention provides a powder coating comprising the following components in percentage by volume:

[0006]

[0007] The volumes stated are loose fill volumes.

[0008] Preferably, the powder coating is in the form of spherical particles, and the average particle size of the spherical particles is 25 to 80 μm.

[0009] Preferably, the volume percentages of SiC and MoSi2 in the powder coating are the same.

[0010] Preferably, the loose volume ratio of the Zr element to the Si element in the powder coating is 7:3 to 6:4.

[0011] The present invention also provides a method for preparing the powder coating according to the above technical solution, comprising the following steps:

[0012] Mixing ZrB2, SiC, MoSi2, Gd2O3, a binder and water to obtain a slurry;

[0013] The slurry is spray-dried and then spheroidized to obtain the powder coating.

[0014] Preferably, the binder comprises polyvinyl alcohol, and the volume ratio of the total loose fill volume of the ZrB2, SiC, MoSi2 and Gd2O3 to the binder is 100:0.4-0.5;

[0015] The water includes deionized water, and the volume ratio of the total loose fill volume of the ZrB2, SiC, MoSi2 and Gd2O3 to water is 1:1.4-1.6;

[0016] The mixing method includes ball milling, the ball milling time is 2.5 to 3.5 hours, and the rotation speed of the ball mill is 160 to 200 rpm.

[0017] Preferably, the spray drying conditions include: inlet temperature: 240-260°C; outlet temperature: 120-140°C; feed speed: 35-45 rpm; nozzle speed: 35-45 Hz;

[0018] The spheroidization treatment method includes induction plasma spheroidization, and the conditions of the induction plasma spheroidization include: Ar flow rate: 55-65 SCFH; H2 flow rate: 5-7 SCFH; processing chamber pressure: 14-16 PSI; powder feeding rate: 4-6 rpm.

[0019] The present invention also provides a coating, wherein the preparation method of the coating comprises the following steps:

[0020] Plasma spraying powder coating on the surface of the substrate to form a coating;

[0021] The powder coating is the powder coating described in the above technical solution or the powder coating prepared by the preparation method described in the above technical solution.

[0022] Preferably, the plasma spraying includes atmospheric plasma spraying;

[0023] The atmospheric plasma spraying conditions include: current 900-950A, main gas flow rate 80-90lpm, auxiliary gas flow rate 50-55lpm, carrier gas flow rate 10-12lpm, powder feeding rate 3-5rpm, spraying distance 55-65cm;

[0024] The matrix includes a C / C composite material.

[0025] The present invention also provides an application of the coating described in the above technical solution in ultra-high temperature components, including ultra-high temperature components in hypersonic aircraft, metallurgy or energy fields.

[0026] The present invention provides a powder coating comprising the following components by volume: 62.4-73.8% ZrB2, 8.8-10.6% SiC, 8.8-10.6% MoSi2, and 5-20% Gd2O3; the volumes indicated are loose fill volumes. A coating formed from the powder coating has excellent infrared emissivity and thermal conductivity, can reduce the coating's service temperature, slow the coating's ablation behavior, and improve the coating's resistance to oxidation and ablation.

[0027] Improve infrared emissivity and heat conduction capability: The present invention doped MoSi2 and Gd2O3 into the ZrB2 / SiC coating to enhance the infrared radiation capability of the coating formed by the coating, increase the infrared emissivity of the coating, thereby increasing the heat conduction of the coating and reducing the service temperature of the coating; this effect is due to the MoSi2 4+ Doped Gd2O3 has a higher emission rate. Specifically, due to the Mo 4+ The charge density of Gd2O3 changes due to the doping of Mo 4+ With Gd 3+ Therefore, the charge density density is different due to the different chemical valence states of the ions, and the difference in ion valence states leads to chemical changes in the defects, forming oxygen vacancies), broken bonds, and the generation of oxygen vacancy defects.

[0028] Delaying ablation: According to the Stefan-Boltzmann law, as temperature increases, thermal radiation gradually becomes dominant in heat transfer. During the ablation process, the coating's infrared radiation capacity directly determines the temperature range within which the coating itself operates. The coating provided by this invention can lower its own temperature, thereby delaying ablation, thanks to its high infrared emissivity and excellent heat conduction capabilities.

[0029] Improved resistance to oxidation and ablation: Traditional ZrB2 / SiC coatings use glass phase to seal defects to achieve resistance to oxidation and ablation, while the coating provided by the present invention (rare earth oxide modified ZrB2 / SiC coating) introduces an additional radiation heat conduction method, which slows down the heating rate of the coating, slows down the loss of the coating due to oxidation and ablation, improves the coating's resistance to oxidation and ablation, and extends the life of components. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the SEM image of the coating prepared in Comparative Example 1;

[0031] Figure 2 This is a SEM image of the coating prepared in Example 1;

[0032] Figure 3 Graph showing the temperature changes over time during the oxyacetylene ablation test of the coatings of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0033] The present invention provides a powder coating comprising the following components in percentage by volume:

[0034]

[0035] The volumes stated are loose fill volumes.

[0036] Calculated by loose fill volume percentage, the powder coating provided by the present invention includes 62.4-73.8% ZrB2, which can be specifically 62.4%, 65%, 70% or 73%.

[0037] Calculated by loose fill volume percentage, the powder coating provided by the present invention comprises 8.8-10.6% SiC, which may be specifically 8.8%, 9%, 10% or 10.6%.

[0038] Calculated by loose fill volume percentage, the powder coating provided by the present invention includes 8.8-10.6% MoSi2, which can be specifically 8.8%, 9%, 10% or 10.6%.

[0039] Calculated by loose fill volume percentage, the powder coating provided by the present invention includes 5-20% Gd2O3, which can be specifically 5%, 8%, 10%, 13%, 15%, 18% or 20%.

[0040] As a specific embodiment of the present invention, the volume percentages of SiC and MoSi2 in the powder coating may be the same; the loose fill volume ratio of Zr element to Si element in the powder coating may be 7:3 to 6:4, and may be specifically 7:3.

[0041] As a specific embodiment of the present invention, the powder coating may be spherical particles, and the average particle size of the spherical particles may be 25 to 90 μm, or 30 to 80 μm, specifically 30 μm, 40 μm, 50 μm, 60 μm, 70 μm or 80 μm.

[0042] The coating formed by the powder coating provided by the present invention has unique structure and performance. In terms of structure, the doping of rare earth oxides Gd2O3 and MoSi2 changes the microstructure of the coating, making it more dense. In terms of performance, Mo 4+ 、Gd 3+ Doping not only changes the charge density of the atoms at the substitution sites, but also leads to broken bonds between atoms near the substitution sites, promotes the generation of oxygen vacancy defects, and intensifies the local vibration centered on the defects, thereby improving the infrared radiation capability of the coating. 4+ 、Gd 3+The high infrared emissivity can increase the thermal conductivity of the coating, reduce the service temperature of the coating, and prevent the coating from reaching very high temperatures in a short period of time due to the low high-temperature emissivity, thereby improving the service limit of the coating.

[0043] The present invention also provides a method for preparing the powder coating according to the above technical solution, comprising the following steps:

[0044] Mixing ZrB2, SiC, MoSi2, Gd2O3, a binder and water to obtain a slurry;

[0045] The slurry is spray-dried and then spheroidized to obtain the powder coating.

[0046] The present invention mixes ZrB2, SiC, MoSi2, Gd2O3, a binder and water to obtain slurry. As a specific embodiment of the present invention, the ZrB2 can be ZrB2 powder, and the average particle size of the ZrB2 powder can be 1 to 3 μm, specifically 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm; the SiC can be SiC powder, and the average particle size of the SiC powder can be 1 to 3 μm, specifically 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm; the MoSi2 can be MoSi2 powder, and the average particle size of the MoSi2 powder can be 1 to 3 μm, specifically 1 μm, 1.5 μm, 2 μm, 2.5 μm or 3 μm; the Gd2O3 can be Gd2O3 powder, and the average particle size of the Gd2O3 powder can be 0.4 to 0.6 μm, specifically 0.4 μm, 0.5 μm or 0.6 μm.

[0047] In one embodiment of the present invention, the binder may include polyvinyl alcohol, and the volume ratio of the total bulk volume of the ZrB2, SiC, MoSi2, and Gd2O3 to the binder may be 100:0.4 to 0.5, specifically 100:0.4, 100:0.45, or 100:0.5. In the present invention, the binder facilitates the bonding of ZrB2, SiC, MoSi2, and Gd2O3, thereby facilitating the formation of spherical particles.

[0048] As a specific embodiment of the present invention, the water may include deionized water, and the volume ratio of the total loose fill volume of the ZrB2, SiC, MoSi2 and Gd2O3 to water may be 1:1.4 to 1.6, and may specifically be 1:1.4, 1:1.5 or 1:1.6.

[0049] As a specific embodiment of the present invention, the mixing method may include ball milling, and the ball milling time may be 2.5 to 3.5 hours, specifically 2.5 hours, 3 hours or 3.5 hours; the ball milling speed may be 160 to 200 rpm, specifically 160 rpm, 170 rpm, 180 rpm, 190 rpm or 200 rpm.

[0050] After obtaining the slurry, the present invention spray-dries the slurry and then spheroidizes it to obtain the powder coating. In a specific embodiment of the present invention, the spray-drying conditions may include: inlet temperature: 240-260°C; outlet temperature: 120-140°C; feed rate: 35-45 rpm; nozzle speed: 35-45 Hz; specifically, inlet temperature: 250°C; outlet temperature: 130°C; feed rate: 40 rpm; nozzle speed: 40 Hz. The present invention can agglomerate the mixed powders of ZrB2, SiC, MoSi2, and Gd2O3 through spray drying.

[0051] As a specific embodiment of the present invention, the spheroidization treatment method may include induction plasma spheroidization, and the conditions of the induction plasma spheroidization include: Ar flow rate: 55~65SCFH; H2 flow rate: 5~7SCFH; processing chamber pressure: 14~16PSI; powder feeding rate: 4~6rpm; specifically: Ar flow rate: 60SCFH; H2 flow rate: 6SCFH; processing chamber pressure: 15PSI; powder feeding rate: 5rpm.

[0052] The present invention also provides a coating, wherein the preparation method of the coating comprises the following steps:

[0053] Plasma spraying powder coating on the surface of the substrate to form a coating;

[0054] The powder coating is the powder coating described in the above technical solution or the powder coating prepared by the preparation method described in the above technical solution.

[0055] As a specific embodiment of the present invention, the matrix may include a C / C composite material; the matrix may specifically be a hypersonic aircraft.

[0056] As a specific embodiment of the present invention, the plasma spraying may include atmospheric plasma spraying; the conditions of the atmospheric plasma spraying may include: current 900-950A, main gas flow 80-90lpm, auxiliary gas flow 50-55lpm, carrier gas flow 10-12lpm, powder feeding rate 3-5rpm, spraying distance 55-65cm, which may be specifically current 900A, main gas flow 80lpm, auxiliary gas flow 50lpm, carrier gas flow 10lpm, powder feeding rate 3rpm, spraying distance 55cm; current 925A, main gas flow 85lpm, auxiliary gas flow 52lpm, carrier gas flow 11lpm, powder feeding rate 4rpm, spraying distance 60cm or current 950A, main gas flow 90lpm, auxiliary gas flow 55lpm, carrier gas flow 12lpm, powder feeding rate 5rpm, spraying distance 65cm.

[0057] The present invention is through Mo 4+ 、Gd 3+ Doping increases infrared emissivity, enhances heat dissipation, and reduces service temperature. Compared with traditional ZrB2 / SiC coatings, its anti-oxidation and ablation capabilities are significantly improved, effectively solving the performance degradation problem caused by SiO2 volatilization at high temperatures. It can be widely used in the protection of ultra-high temperature components in hypersonic aircraft, metallurgy, energy and other fields.

[0058] The present invention also provides an application of the coating described in the above technical solution in ultra-high temperature components, which may include ultra-high temperature components in hypersonic aircraft, metallurgy or energy fields.

[0059] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0060] Example 1

[0061] Slurry preparation: ZrB2 powder with an average particle size of 2 μm, SiC powder with an average particle size of 2 μm, MoSi2 powder with an average particle size of 2 μm, and Gd2O3 powder with an average particle size of 0.5 μm were placed in a stirred ball mill at a loose filling volume ratio of 62.4:8.8:8.8:20, and deionized water (the volume ratio of the total loose filling volume of ZrB2 powder, SiC powder, MoSi2 powder and Gd2O3 powder to deionized water is 1:1.5) and polyvinyl alcohol (the volume ratio of the total loose filling volume of ZrB2 powder, SiC powder, MoSi2 powder and Gd2O3 powder to polyvinyl alcohol is 100:0.5) were added. The mixture was ball milled at a rotation speed of 180 rpm for 3 h to obtain a slurry.

[0062] Preparation of powder coating: The slurry is spray dried to obtain agglomerated powder; the agglomerated powder is then subjected to induction plasma spheroidization treatment to obtain powder coating (ZrB2-SiC composite powder modified by doping MoSi2 / Gd2O3); the spray drying conditions are as follows: inlet temperature: 250°C; outlet temperature: 130°C; feed speed: 40 rpm; nozzle speed: 40 Hz; the induction plasma spheroidization treatment conditions are as follows: Ar flow rate: 60 SCFH; H2 flow rate: 6 SCFH; treatment chamber pressure: 15 PSI; powder feeding rate: 5 rpm.

[0063] Coating preparation: Powder coating was plasma sprayed on the surface of the C / C composite material by atmospheric plasma spraying to form a coating. The atmospheric plasma spraying conditions were as follows: current 900 A, main gas flow 80 lpm, auxiliary gas flow 50 lpm, carrier gas flow 10 lpm, powder feeding rate 3 rpm, and spraying distance 55 cm.

[0064] Example 2

[0065] Prepare a slurry according to the method of Example 1;

[0066] Prepare a powder coating according to the method of Example 1;

[0067] The coating was prepared according to the method of Example 1, except that the atmospheric plasma spraying conditions were as follows: current 925 A, main gas flow 85 lpm, auxiliary gas flow 52 lpm, carrier gas flow 11 lpm, powder feeding rate 4 rpm, and spraying distance 60 cm.

[0068] Example 3

[0069] Prepare a slurry according to the method of Example 1;

[0070] Prepare a powder coating according to the method of Example 1;

[0071] The coating was prepared according to the method of Example 1, except that the atmospheric plasma spraying conditions were as follows: current 950 A, main gas flow 90 lpm, auxiliary gas flow 55 lpm, carrier gas flow 12 lpm, powder feeding rate 5 rpm, and spraying distance 65 cm.

[0072] Comparative Example 1 (undoped MoSi2 and Gd2O3)

[0073] Slurry preparation: ZrB2 powder with an average particle size of 2 μm and SiC powder with an average particle size of 2 μm were placed in a stirred ball mill at a loose filling volume ratio of 7:3, and deionized water (the volume ratio of the total loose filling volume of ZrB2 powder and SiC powder to deionized water was 1:1.5) and polyvinyl alcohol (the volume ratio of the total loose filling volume of ZrB2 powder and SiC powder to polyvinyl alcohol was 100:0.5) were added. The mixture was ball milled at a speed of 180 rpm for 3 h to obtain a slurry.

[0074] A powder coating was prepared according to the method of Example 1.

[0075] The coating was prepared according to the method of Example 1.

[0076] Comparative Example 2

[0077] The slurry was prepared according to the method of the embodiment, except that the loose fill volume ratio of ZrB2 powder, SiC powder, MoSi2 powder and Gd2O3 powder was 54.4:7.8:7.8:30.

[0078] A powder coating was prepared according to the method of Example 1.

[0079] The coating was prepared according to the method of Example 1.

[0080] The coatings prepared in Example 1 and Comparative Example 1 were examined by scanning electron microscopy to obtain SEM images. Figure 1 、 2 shown. Figure 1 This is the SEM image of the coating prepared in Comparative Example 1. Figure 2 This is the SEM image of the coating prepared in Example 1.

[0081] Depend on Figure 1 It can be seen that there are obvious holes in the unmodified coating of Comparative Example 1; Figure 2 The ZrB2 / SiC coating modified with MoSi2 / Gd2O3 is dense and has low porosity;

[0082] The coatings of Examples 1 to 3 and Comparative Examples 1 to 2 were subjected to oxyacetylene ablation tests with reference to GJB323A-96 "Ablation Test Method for Ablative Materials". The specific conditions were: oxygen flow rate 1512 L / h, acetylene flow rate 1116, oxygen pressure 0.4 MPa, acetylene pressure 0.095 MPa, distance from sample surface to nozzle 10 mm, flame heat flux density 4.18 MW / m 2 ; The specific results are listed in Table 1. The results of the coating temperature changes over time in Example 1 and Comparative Example 1 are as follows Figure 3 shown.

[0083] Table 1 Ablation performance of coatings in Examples 1 to 3 and Comparative Example 1

[0084]

[0085] Combined with Table 1 and Figure 3 As can be seen, the coating provided by Example 1 of the present invention has a low equilibrium temperature and a low mass loss rate. By comparison, the unmodified coating (Comparative Example 1) has a high equilibrium temperature and a high mass loss rate, and its antioxidant and ablation resistance is significantly lower than that of the modified coating prepared by the present invention. This fully demonstrates that the coating of the present invention effectively solves the problems of poor coating density and insufficient antioxidant and ablation resistance.

[0086] The SEM test results and oxyacetylene ablation test results of Example 2 and Example 3 are similar to those of Example 1. The coatings of Example 2 and Example 3 have good density, good stability in high temperature environment, low heating rate and low temperature performance, indicating that the coatings provided by the present invention have good anti-oxidation and ablation capabilities.

[0087] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A powder coating, characterized in that: The following components are included in percentage by volume: The volumes stated are loose fill volumes.

2. The powder coating according to claim 1, characterized in that: The powder coating is in the form of spherical particles, and the average particle size of the spherical particles is 25 to 80 μm.

3. The powder coating according to claim 1 or 2, characterized in that: The volume percentages of the SiC and MoSi2 in the powder coating are the same.

4. The powder coating according to claim 3, characterized in that: The loose fill volume ratio of the Zr element to the Si element in the powder coating is 7:3 to 6:

4.

5. The method for preparing the powder coating according to any one of claims 1 to 4, characterized in that: The following steps are involved: Mixing ZrB2, SiC, MoSi2, Gd2O3, a binder and water to obtain a slurry; The slurry is spray-dried and then spheroidized to obtain the powder coating.

6. The preparation method according to claim 5, characterized in that The binder includes polyvinyl alcohol, and the volume ratio of the total loose fill volume of ZrB2, SiC, MoSi2 and Gd2O3 to the binder is 100:0.4-0.5; The water includes deionized water, and the volume ratio of the total loose fill volume of the ZrB2, SiC, MoSi2 and Gd2O3 to water is 1:1.4-1.6; The mixing method includes ball milling, the ball milling time is 2.5 to 3.5 hours, and the rotation speed of the ball mill is 160 to 200 rpm.

7. The preparation method according to claim 5, characterized in that The spray drying conditions include: inlet temperature: 240-260°C; outlet temperature: 120-140°C; feed speed: 35-45 rpm; nozzle speed: 35-45 Hz; The spheroidization treatment method includes induction plasma spheroidization, and the conditions of the induction plasma spheroidization include: Ar flow rate: 55-65 SCFH; H2 flow rate: 5-7 SCFH; processing chamber pressure: 14-16 PSI; powder feeding rate: 4-6 rpm.

8. A coating, characterized in that The method for preparing the coating comprises the following steps: Plasma spraying powder coating on the surface of the substrate to form a coating; The powder coating is the powder coating according to any one of claims 1 to 4 or the powder coating prepared by the preparation method according to any one of claims 5 to 7.

9. The coating according to claim 8, characterized in that The plasma spraying includes atmospheric plasma spraying; The atmospheric plasma spraying conditions include: current 900-950A, main gas flow rate 80-90lpm, auxiliary gas flow rate 50-55lpm, carrier gas flow rate 10-12lpm, powder feeding rate 3-5rpm, spraying distance 55-65cm; The matrix includes a C / C composite material.

10. Use of the coating according to claim 8 or 9 in ultrahigh temperature components, wherein the ultrahigh temperature components include ultrahigh temperature components in the fields of hypersonic aircraft, metallurgy or energy.

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