阅读说明：本技术 一种耐高温复合涂层及其制备工艺 (High-temperature-resistant composite coating and preparation process thereof ) 是由 吴宝林 侯振华 吴迪 于 2020-11-23 设计创作，主要内容包括：本发明提供了一种耐高温复合涂层的制备工艺,是通过采用SiC粉末作为涂层的主体材料,采用无机玻璃粉改性SiC,以提高其在高温下的流动性,使SiC能均匀地覆盖C/C复合材料的表面；在反应釜中加入超细硅粉,一方面,高温下硅粉能与C/C复合材料表面反应,生成目标涂层产物SiC,另一方面Si粉附着在SiC表面,使SiC涂层颗粒进一步增长,提高SiC涂层颗粒之间的粘结力。SiC涂层生成结束后,在体系内通入氨气和三卤化硼的混合气体,并且加入ZrO2,使其在C/C复合材料表面进一步生成含有ZrO2的BN压应力涂层。同时还提供了上述工艺获得的耐高温复合材料涂层,具有良好的耐高温氧化性能。(The invention provides a preparation process of a high-temperature-resistant composite coating, which adopts SiC powder as a main material of the coating, and adopts inorganic glass powder to modify SiC so as to improve the fluidity of the coating at high temperature and ensure that the SiC can uniformly cover the surface of a C/C composite material; adding superfine silicon powder into a reaction kettle, wherein on one hand, the silicon powder can react with the surface of the C/C composite material at high temperature to generate a target coating product SiC, and on the other hand, Si powder is attached to the surface of the SiC, so that SiC coating particles are further increased, and the binding power among the SiC coating particles is improved. And after the SiC coating is generated, introducing mixed gas of ammonia gas and boron trihalide into the system, and adding ZrO2 to further generate a BN compressive stress coating containing ZrO2 on the surface of the C/C composite material. Meanwhile, the high-temperature-resistant composite material coating obtained by the process is provided, and has good high-temperature oxidation resistance.)

1. A preparation process of a high-temperature-resistant composite coating is characterized by comprising the following steps: the specific process steps are

(1) Ultrasonically oscillating the C/C composite material in ethanol for 15-30min, taking out, washing with pure ethanol, and drying in a muffle furnace at 60-80 ℃ for more than 24 hours;

(2) putting a proper amount of polyvinyl alcohol (PVA) into deionized water, heating to 90-95 ℃ in a water bath, and continuously stirring until a uniform solution is formed, and marking as a solution 1;

(3) taking SiC powder and low-melting-point inorganic glass powder, sieving with a 800-mesh sieve, adding into the solution 1, keeping the water bath heating at 90-95 ℃, and continuously stirring until deionized water is evaporated; putting the mixture into a muffle furnace, and continuously drying the mixture at the temperature of between 90 and 100 ℃ until the mixture is completely dried; grinding in a ball mill for 24-48 hours by a dry method, sieving with a 1250-mesh sieve, and recording the sieved product as a mixture 2;

(4) wetting the surface of the C/C composite material obtained in the step (1) with tetraethoxysilane, trowelling and scraping redundant tetraethoxysilane by a blade, and uniformly coating the mixture 2 on the surface of the C/C composite material, wherein the thickness is controlled to be 300-;

(5) sieving the superfine silicon powder with 1250-mesh sieve, and drying in a muffle furnace at 80-100 ℃ for 6-8 hours; putting silicon powder into a reaction kettle, and putting the C/C composite material obtained in the step (4) above the silicon powder without directly contacting the silicon powder; introducing inert gas into the reaction kettle, heating according to a heating program, cooling to 800-; (ii) a

(6) Drying ZrO after heat preservation₂Sieving the powder with 1250 mesh sieve, adding the powder into a reaction kettle from a charging valve, and ZrO₂The mass of the powder is 0.5-1% of that of the C/C composite material; heating the reaction kettle, keeping the flow of the inert gas unchanged in the heating process, and introducing mixed gas of ammonia gas and boron trihalide; stopping introducing the mixed gas of ammonia gas and boron trihalide for 0.5-1 hour after the temperature rise is finished; and preserving heat for a period of time, cooling after heat preservation is finished, and cooling to room temperature along with the furnace to obtain the high-temperature-resistant composite material coating on the surface of the C/C composite material.

2. The preparation process of the high-temperature-resistant composite coating according to claim 1, characterized in that: in the step (2), the mass ratio of the polyvinyl alcohol PVA to the deionized water is (3-6): 100.

3. the preparation process of the high-temperature-resistant composite coating according to claim 1, characterized in that: in the step (3), the mass ratio of the SiC powder, the inorganic glass powder and the solution 1 is 100: (5-20): (300-600).

4. The preparation process of the high-temperature-resistant composite coating according to claim 1, characterized in that: in the step (5), the mass of the silicon powder is 1-2% of that of the C/C composite material; the inert gas is high-purity nitrogen or argon, and the flow rate is 200-600 ml/min.

5. The preparation process of the high-temperature-resistant composite coating according to claim 1, characterized in that: in the step (5), the temperature raising procedure is as follows: raising the temperature to 1800-2000 ℃ at a speed of 5-10 ℃/min, and preserving the heat for 2-4 hours; then cooling at 5-10 deg.C/min.

6. The preparation process of the high-temperature-resistant composite coating according to claim 1, characterized in that: in the step (6), introducing mixed gas of ammonia gas and boron trihalide in a flow ratio of 1: 1, the total flow rate is 300-500 ml/min.

7. The preparation process of the high-temperature-resistant composite coating according to claim 1, characterized in that: in step (6), the boron trihalide comprises any one of boron trichloride, boron tribromide, or a combination of both.

8. The preparation process of the high-temperature-resistant composite coating according to claim 1, characterized in that: in the step (6), the temperature of the reaction kettle is raised to 1250-1300 ℃ at the speed of 1-3 ℃/min, and the temperature is kept for 1-2 hours; keeping the flow of the inert gas unchanged in the temperature rising process, and simultaneously introducing mixed gas of ammonia gas and boron trihalide; stopping introducing the mixed gas of ammonia gas and boron trihalide for 0.5-1 hour after the temperature rise is finished; after the heat preservation is finished, the temperature is reduced to 800-1000 ℃ at the speed of 5-10 ℃/min, and then the temperature is cooled to the room temperature along with the furnace.

9. A coating prepared according to the preparation process of the high-temperature resistant composite coating of any one of claims 1 to 8, wherein: is used for preparing the C/C composite material.

Technical Field

The invention belongs to the technical field of high-temperature coating preparation, and particularly relates to a high-temperature-resistant composite coating and a preparation process thereof.

Background

The C/C composite material has the advantages of light weight, high strength and good high temperature resistance in an oxygen-free environment, and has great application prospects in the fields of aerospace, weaponry, rocket missiles and the like. However, the C/C composite material is oxidized at a temperature of more than 400 ℃ in an aerobic environment, so that the performance is reduced, and the application of the C/C composite material in the field of high-temperature thermal structures is limited. A high-temperature-resistant and oxidation-resistant coating is prepared on the surface of the C/C composite material, is one of effective methods for improving the service temperature of the C/C composite material and expanding the service field of the C/C composite material, and is widely applied at home and abroad.

The coating of the current C/C composite material mainly comprises oxides and carbides of refractory metals and a high-temperature oxidation-resistant ceramic coating. The SiC coating is one of the widely used coatings at present due to the small thermal expansion coefficient, good high temperature resistance, oxidation resistance and mechanical property. Methods for preparing SiC coatings include embedding, chemical vapor deposition, plasma spraying, and the like. However, the SiC coating still has the problems of weak bonding force with a C/C composite material matrix and easy stripping and falling off from the surface of the C/C composite material in a high-temperature oxidation environment, and cannot achieve an ideal protection effect.

Disclosure of Invention

In order to overcome the technical problems that the existing C/C composite material is oxidized at the temperature of more than 400 ℃ in an aerobic environment to cause performance reduction, the SiC coating is coated, but the SiC coating is easy to peel off and fall off from the surface of the C/C composite material, the invention improves the SiC coating, and particularly provides a preparation process of a high-temperature-resistant composite coating, which comprises the following specific process steps:

(1) ultrasonically oscillating the C/C composite material in ethanol for 15-30min, taking out, washing with pure ethanol, and drying in a muffle furnace at 60-80 ℃ for more than 24 hours;

(2) putting a proper amount of polyvinyl alcohol (PVA) into deionized water, heating to 90-95 ℃ in a water bath, and continuously stirring until a uniform solution is formed, and marking as a solution 1;

(3) taking SiC powder and low-melting-point inorganic glass powder, sieving with a 800-mesh sieve, adding into the solution 1, keeping the water bath heating at 90-95 ℃, and continuously stirring until deionized water is evaporated; putting the mixture into a muffle furnace, and continuously drying the mixture at the temperature of between 90 and 100 ℃ until the mixture is completely dried; grinding in a ball mill for 24-48 hours by a dry method, sieving with a 1250-mesh sieve, and recording the sieved product as a mixture 2;

(4) wetting the surface of the C/C composite material obtained in the step (1) with tetraethoxysilane, trowelling and scraping redundant tetraethoxysilane by a blade, and uniformly coating the mixture 2 on the surface of the C/C composite material, wherein the thickness is controlled to be 300-;

(5) sieving the superfine silicon powder with 1250-mesh sieve, and drying in a muffle furnace at 80-100 ℃ for 6-8 hours; putting silicon powder into a reaction kettle, and putting the C/C composite material obtained in the step (4) above the silicon powder without directly contacting the silicon powder; introducing inert gas into the reaction kettle, heating according to a heating program, cooling to 800-; (ii) a

(6) After heat preservation is finished, sieving dry ZrO2 powder with a 1250-mesh sieve, and adding the powder into a reaction kettle from a feeding valve, wherein the mass of the ZrO2 powder is 0.5-1% of that of the C/C composite material; heating the reaction kettle, keeping the flow of the inert gas unchanged in the heating process, and introducing mixed gas of ammonia gas and boron trihalide; stopping introducing the mixed gas of ammonia gas and boron trihalide for 0.5-1 hour after the temperature rise is finished; and preserving heat for a period of time, cooling after heat preservation is finished, and cooling to room temperature along with the furnace to obtain the high-temperature-resistant composite material coating on the surface of the C/C composite material.

As an improvement, in the step (2), the mass ratio of the polyvinyl alcohol PVA to the deionized water is (3-6): 100.

as an improvement, in the step (3), the mass ratio of the SiC powder, the inorganic glass powder and the solution 1 is 100: (5-20): (300-600).

As an improvement, in the step (5), the mass of the silicon powder is 1-2% of that of the C/C composite material; the inert gas is high-purity nitrogen or argon, and the flow rate is 200-600 ml/min.

As a modification, in the step (5), the temperature raising procedure is as follows: raising the temperature to 1800-2000 ℃ at a speed of 5-10 ℃/min, and preserving the heat for 2-4 hours; then cooling at 5-10 deg.C/min.

As an improvement, in the step (6), in the temperature rising process, mixed gas of ammonia gas and boron trihalide is introduced, and the flow ratio is 1: 1, the total flow rate is 300-500 ml/min.

In step (6), the boron trihalide may be any one of boron trichloride and boron tribromide, or a combination of these two.

As an improvement, in the step (6), the temperature of the reaction kettle is raised to 1250-; keeping the flow of the inert gas unchanged in the temperature rising process, and simultaneously introducing mixed gas of ammonia gas and boron trihalide; stopping introducing the mixed gas of ammonia gas and boron trihalide for 0.5-1 hour after the temperature rise is finished; after the heat preservation is finished, the temperature is reduced to 800-1000 ℃ at the speed of 5-10 ℃/min, and then the temperature is cooled to the room temperature along with the furnace.

Meanwhile, the coating prepared by the preparation process of the high-temperature-resistant composite coating is also provided and is used for preparing a C/C composite material.

Has the advantages that: the invention provides a preparation process of a high-temperature-resistant composite coating, which adopts SiC powder as a main material of the coating and adopts inorganic glass powder to modify SiC so as to improve the fluidity of the coating at high temperature and ensure that the SiC can uniformly cover the surface of a C/C composite material; adding superfine silicon powder into a reaction kettle, wherein on one hand, the silicon powder can react with the surface of the C/C composite material at high temperature to generate a target coating product SiC, and on the other hand, Si powder is attached to the surface of the SiC, so that SiC coating particles are further increased, and the binding power among the SiC coating particles is improved. After the SiC coating is generated, introducing mixed gas of ammonia gas and boron trihalide into the system, and adding ZrO₂To further form a layer containing ZrO on the surface of the C/C composite material₂BN compressive stress coating of (1). The compressive stress BN coating enables the SiC coating to be bonded with the C/C composite material more tightly; ZrO (ZrO)₂The phase change occurs in the material cooling process to cause volume expansion, and the density of the coating is further improved.

Detailed Description

The following examples are given to further illustrate the embodiments of the present invention. The following examples are intended to illustrate the invention but are not intended to limit the scope of the invention.

The high temperature resistant composite coating prepared by the present invention has good high temperature oxidation resistance, and is further described in the following examples.

The first embodiment is as follows:

1. and ultrasonically oscillating the C/C composite material in ethanol for 15min, taking out, washing with pure ethanol, and drying in a muffle furnace at 60 ℃ for 24 hours.

2. Placing a proper amount of PVA in deionized water, heating to 90 ℃ in a water bath, and continuously stirring until a uniform solution is formed, and marking as a solution 1; wherein the mass ratio of PVA to deionized water is 3: 100.

3. taking SiC powder and low-melting-point inorganic glass powder, sieving with a 800-mesh sieve, adding into the solution 1, keeping the water bath heating at 90 ℃, and continuously stirring until deionized water is evaporated; putting the mixture into a muffle furnace, and continuously drying the mixture at 90 ℃ until the mixture is completely dried; grinding the mixture in a ball mill for 24 hours by a dry method, sieving the mixture by a 1250-mesh sieve, and recording a sieved product as a mixture 2; wherein the mass ratio of the SiC powder to the inorganic glass powder to the solution 1 is 100: 5: 300.

4. wetting the surface of the C/C composite material obtained in the step one by using tetraethoxysilane, leveling by using a blade and scraping redundant tetraethoxysilane, and uniformly coating the mixture 2 on the surface of the C/C composite material with the thickness of 300 mu m.

5. Sieving the superfine silicon powder with 1250-mesh sieve, and drying in a muffle furnace at 80 ℃ for 6 hours; putting silicon powder into a reaction kettle, and putting the C/C composite material obtained in the step (4) above the silicon powder without directly contacting the silicon powder, wherein the mass of the silicon powder is 1% of that of the C/C composite material; introducing inert gas into the reaction kettle, and controlling the temperature rise program as follows: heating to 1800 ℃ at the speed of 5 ℃/min, and preserving heat for 2 hours; then, the temperature is reduced to 800 ℃ at the speed of 5 ℃/min, and the temperature is kept for 0.5 hour; wherein the inert gas is high-purity nitrogen, and the flow rate is 200 ml/min.

6. Drying ZrO after heat preservation₂Sieving the powder with 1250 mesh sieve, adding the powder into a reaction kettle from a charging valve, and ZrO₂The mass of the powder is 0.5 percent of that of the C/C composite material; heating the reaction kettle to 1250 ℃ at the speed of 1 ℃/min and preserving the heat for 1 hour; keeping the flow of the inert gas unchanged in the temperature rising process, and simultaneously introducing mixed gas of ammonia gas and boron trihalide, wherein the flow ratio is 1: 1, the total flow rate is 300 ml/min; stopping introducing the mixed gas of ammonia gas and boron trihalide 0.5 hour after the temperature rise is finished; after the heat preservation is finished, setting a cooling program to cool to 800 ℃ at a speed of 5 ℃/min, and then cooling to room temperature along with a furnace, namely preparing a high-temperature-resistant composite material coating on the surface of the C/C composite material; wherein the boron trihalide is boron trichloride.

The C/C composite material protected by the coating prepared in this example had a mass ablation rate of 0.42mg/s and a line ablation rate of 0.39X 10 according to the oxy-acetylene ablation test method GJB 323A-1996 ablation Material ablation test method^-3mm/s.

The second embodiment is as follows:

1. and ultrasonically oscillating the C/C composite material in ethanol for 30min, taking out, washing with pure ethanol, and drying in a muffle furnace at 80 ℃ for 48 hours.

2. Placing a proper amount of PVA in deionized water, heating to 95 ℃ in a water bath, and continuously stirring until a uniform solution is formed, and marking as a solution 1; wherein the mass ratio of PVA to deionized water is 6: 100.

3. taking SiC powder and low-melting-point inorganic glass powder, sieving with a 800-mesh sieve, adding into the solution 1, keeping the water bath heating at 95 ℃, and continuously stirring until deionized water is evaporated; putting the mixture into a muffle furnace, and continuously drying the mixture at 100 ℃ until the mixture is completely dried; grinding the mixture in a ball mill for 48 hours by a dry method, sieving the mixture by a 1250-mesh sieve, and recording a sieved product as a mixture 2; wherein the mass ratio of the SiC powder to the inorganic glass powder to the solution 1 is 100: 20: 600.

4. wetting the surface of the C/C composite material obtained in the step one by using tetraethoxysilane, leveling by using a blade and scraping redundant tetraethoxysilane, and uniformly coating the mixture 2 on the surface of the C/C composite material with the thickness of 600 mu m.

5. Sieving the superfine silicon powder with 1250-mesh sieve, and drying in a muffle furnace at 100 ℃ for 8 hours; putting silicon powder into a reaction kettle, and putting the C/C composite material obtained in the step (4) above the silicon powder without directly contacting the silicon powder, wherein the mass of the silicon powder is 2% of that of the C/C composite material; introducing inert gas into the reaction kettle, and controlling the temperature rise program as follows: heating to 2000 deg.C at 10 deg.C/min, and maintaining for 4 hr; then cooling to 1200 ℃ at a speed of 10 ℃/min, and preserving heat for 1 hour; wherein the inert gas is high-purity nitrogen, and the flow rate is 600 ml/min.

6. Drying ZrO after heat preservation₂Sieving the powder with 1250 mesh sieve, adding the powder into a reaction kettle from a charging valve, and ZrO₂The mass of the powder is 1% of that of the C/C composite material; heating the reaction kettle to 1300 ℃ at the speed of 3 ℃/min and preserving the temperature for 2 hours; keeping the flow of the inert gas unchanged in the temperature rising process, and simultaneously introducing mixed gas of ammonia gas and boron trihalide, wherein the flow ratio is 1: 1, the total flow rate is 500 ml/min; stopping introducing the mixed gas of ammonia gas and boron trihalide for 1 hour after the temperature rise is finished; after the heat preservation is finished, setting a temperature reduction program to reduce the temperature to 1000 ℃ at a speed of 10 ℃/min, and then cooling to room temperature along with a furnace, namely preparing a high-temperature-resistant composite material coating on the surface of the C/C composite material;wherein the boron trihalide is boron tribromide.

The C/C composite material protected by the coating prepared in this example had a mass ablation rate of 0.49mg/s and a line ablation rate of 0.45X 10 according to the oxy-acetylene ablation test method GJB 323A-1996 ablation Material ablation test method^-3mm/s。

The third concrete embodiment:

1. and ultrasonically oscillating the C/C composite material in ethanol for 20min, taking out, washing with pure ethanol, and drying in a muffle furnace at 70 ℃ for 24 hours.

2. Placing a proper amount of PVA in deionized water, heating to 93 ℃ in a water bath, and continuously stirring until a uniform solution is formed, and marking as a solution 1; wherein the mass ratio of PVA to deionized water is 5: 100.

3. taking SiC powder and low-melting-point inorganic glass powder, sieving with a 800-mesh sieve, adding into the solution 1, keeping the water bath heating at 93 ℃, and continuously stirring until deionized water is evaporated; putting the mixture into a muffle furnace, and continuously drying the mixture at the temperature of 95 ℃ until the mixture is completely dried; putting the mixture into a ball mill, grinding the mixture for 36 hours by a dry method, sieving the mixture by a 1250-mesh sieve, and marking a sieved product as a mixture 2; wherein the mass ratio of the SiC powder to the inorganic glass powder to the solution 1 is 100: 10: 500.

4. wetting the surface of the C/C composite material obtained in the step one by using tetraethoxysilane, leveling by using a blade and scraping redundant tetraethoxysilane, and uniformly coating the mixture 2 on the surface of the C/C composite material with the thickness of 500 mu m.

5. Sieving the superfine silicon powder with 1250-mesh sieve, and drying in a muffle furnace at 90 ℃ for 7 hours; putting silicon powder into a reaction kettle, and putting the C/C composite material obtained in the step (4) above the silicon powder without directly contacting the silicon powder, wherein the mass of the silicon powder is 1.5 percent of that of the C/C composite material; introducing inert gas into the reaction kettle, and controlling the temperature rise program as follows: heating to 1900 deg.c at 8 deg.c/min and maintaining for 3 hr; then cooling to 1000 ℃ at the speed of 8 ℃/min, and preserving heat for 0.8 hour; wherein the inert gas is high-purity argon, and the flow rate is 400 ml/min.

6. Drying ZrO after heat preservation₂Sieving the powder with 1250 mesh sieve, adding the powder into a reaction kettle from a charging valve, and ZrO₂The mass of the powder is 0.7 percent of that of the C/C composite material; the reaction kettle is heated to 1280 ℃ at the speed of 2 ℃/minAnd keeping the temperature for 1 hour; keeping the flow of the inert gas unchanged in the temperature rising process, and simultaneously introducing mixed gas of ammonia gas and boron trihalide, wherein the flow ratio is 1: 1, the total flow rate is 400 ml/min; stopping introducing the mixed gas of ammonia gas and boron trihalide for 1 hour after the temperature rise is finished; after the heat preservation is finished, setting a temperature reduction program to reduce the temperature to 900 ℃ at the speed of 7 ℃/min, and then cooling to room temperature along with a furnace, namely preparing a high-temperature-resistant composite material coating on the surface of the C/C composite material; wherein the boron trihalide is boron tribromide.

The C/C composite material protected by the coating prepared in this example had a mass ablation rate of 0.35mg/s and a line ablation rate of 0.37X 10 according to the oxy-acetylene ablation test method GJB 323A-1996 ablation Material ablation test method^-3mm/s。

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.