High-efficiency preparation process of short fiber rigid thermal insulation composite material

Abstract

The application provides a high-efficiency preparation process of short-fiber hard thermal insulation composite material: carbon fibers with short fibers as raw materials are immersed in a modifier for surface treatment, then metal modification, carbon layer deposition and inorganic layer coating are sequentially performed on the surface; the carbon fibers and inorganic materials are compounded and hot-pressed, and then high-temperature graphitization treatment is performed, so that the short-fiber hard thermal insulation composite material is obtained. The process can improve the connection strength between the short fibers and the inorganic materials, improve the mechanical properties of the composite material, and has higher graphitization degree and good thermal insulation performance.

Description

Technical Field

[0001] This invention relates to the field of rigid thermal insulation materials, and in particular to an efficient preparation process for a short-fiber rigid thermal insulation composite material. Background Technology

[0002] With the development of science and technology, the role of materials in various fields is becoming increasingly prominent, making the discovery and preparation of new materials increasingly important. However, the discovery of new materials is limited by various conditions, including opportunities. Therefore, utilizing existing materials and modifying or adjusting the preparation process to create new materials has become a crucial demand. The significant thermal expansion and contraction of ceramic materials can reduce the structural stability and reliability of heat-resistant components, weakening or even destroying the material's heat resistance and resistance to oxidation and ablation. Carbon fiber is a new type of high-strength, high-modulus fiber material. Combining carbon fiber with ceramic materials can reduce the internal stress generated by high-temperature expansion, increasing the material's resistance to thermal shock. The resulting rigid thermal insulation materials can be widely used in high-temperature operating environments. Summary of the Invention

[0003] This invention provides an efficient preparation process for a short-fiber rigid thermal insulation composite material: carbon fibers, made from short fibers, are immersed in a modifier for surface treatment, followed by sequential metal modification, carbon layer deposition, and inorganic coating. The carbon fibers and inorganic materials are then hot-pressed together and subjected to high-temperature graphitization to obtain the short-fiber rigid thermal insulation composite material. This process improves the bonding strength between the short fibers and inorganic materials, enhances the mechanical properties of the composite material, and results in a higher degree of graphitization and excellent thermal insulation performance.

[0004] An efficient preparation process for a short-fiber rigid thermal insulation composite material, characterized in that the method includes:

[0005] 1) Take short-cut carbon fibers, disperse them in a mixed solution of acetone and tetrahydrofuran, wash and dry them to obtain pretreated carbon fibers;

[0006] 2) Mix the pretreated carbon fiber and titanium metal nanopowder evenly, then place them in a tube furnace and calcine them at 1000-1200℃ under a protective atmosphere; cool down to 550-650℃, introduce acetylene gas, keep warm for a predetermined time, and cool to room temperature before taking them out.

[0007] 3) The product from step 2 was immersed in a zirconium salt solution, dried, and then placed in a tube furnace. Under a protective atmosphere, it was heated to 550-650℃ and calcined. After cooling to room temperature, it was taken out and crushed to obtain carbon fibers with a titanium carbide layer, a carbon layer and a zirconium carbide layer successively coated on the surface.

[0008] 4) Disperse zirconium oxide powder, silicon carbide powder, carbon fiber obtained in step 3, phenolic resin and silane coupling agent in ethanol, dry, and hot press to set; place the set preform in a tube furnace, heat to 1200-2200℃ under a protective atmosphere and calcine, then cool to 500-600℃ for annealing to obtain short fiber rigid thermal insulation composite material.

[0009] Furthermore, in step 1, the chopped carbon fibers have a diameter of 5-8 μm and a length of 1-2 mm; the mass ratio of acetone to tetrahydrofuran is 1:1-1.5.

[0010] Furthermore, in step 2, the pretreated carbon fiber and titanium metal powder are mixed at a mass ratio of 100:10-15, and the titanium metal powder has a particle size of 500-1000 nm.

[0011] Furthermore, in step 2, the high-temperature calcination in the tube furnace under nitrogen protection is carried out at a temperature of 1000-1200℃ for 4-6 hours; then the temperature is lowered to 550-650℃, acetylene gas is introduced, and the flow rate of the acetylene gas is 100-150 ml / min, and the temperature is maintained for 0.5-3 hours.

[0012] Furthermore, in step 3, the concentration of the zirconium nitrate solution is 8-12 wt%, and the soaking time is 3-6 h.

[0013] Furthermore, in step 3, the calcination temperature under nitrogen protection in the tubular furnace is 550-650℃, and the calcination time is 4-6h.

[0014] Furthermore, in step 4, zirconium oxide powder with an average particle size of 30-50 micrometers, silicon carbide powder with an average particle size of 30-50 micrometers, carbon fiber obtained in step 3, phenolic resin, and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 80-100:80-100:30-60:15-20:3-5, and the solid content is adjusted to 40-60 wt%.

[0015] Furthermore, in step 4, the hot-pressing temperature is 80-90℃, the hot-pressing time is 10-30min, and the hot-pressing pressure is 30-35MPa.

[0016] Furthermore, in step 4, the shaped preform is placed in a tube furnace and calcined at 1200-1400℃ for 6-8 hours under nitrogen protection, then calcined at 1800-2200℃ for 1-2 hours, and then annealed at 500-600℃ for 0.5-1 hours to obtain a short fiber rigid thermal insulation composite material.

[0017] A short-fiber rigid thermal insulation composite material, the material being prepared using the process described above.

[0018] Beneficial technical effects of the present invention

[0019] 1) Titanium metal modification of carbon fiber: During the carbon deposition process, the metal can act as a catalyst to promote carbon deposition and improve the deposition effect. At the same time, it can partially form titanium carbide hard alloy, which can improve the strength of carbon fiber.

[0020] 2) The carbon layer deposited on the carbon fiber surface has a high specific surface area due to the catalytic effect of titanium metal, which is conducive to the adhesion of soluble zirconium salts on the surface. At the same time, zirconium carbide is formed during the heating process. As a material with high hardness and high melting point, zirconium carbide can prevent the carbon fiber from being lost during the high-temperature heating process in the later stage and improve the mechanical properties of the insulation material.

[0021] 3) Zirconium carbide has a high affinity with zirconium oxide and silicon carbide added to the material, which is beneficial to the dispersion of short fibers in the material, avoids agglomeration, thereby reducing thermal conductivity and improving mechanical properties.

[0022] 4) The preparation process of the present invention is low in cost, simple and efficient, and has wide application value. Detailed Implementation

[0023] The present invention will be described in more detail below through specific embodiments, but the scope of protection of the present invention is not limited to these embodiments.

[0024] Example 1:

[0025] 1) Take short-cut carbon fibers with a diameter of 5μm and a length of 1mm, disperse them in a mixed solution of acetone and tetrahydrofuran with a mass ratio of 1:1, then wash them three times with ethanol, and dry them to obtain pretreated carbon fibers.

[0026] 2) The pretreated carbon fiber and titanium metal powder with a particle size of 500 nm were ball-milled at a mass ratio of 100:10, with a ball-to-material ratio of 3:1, a rotation speed of 100 r / min, for 10 h. Then the mixture was placed in a tube furnace and calcined at 1000℃ for 6 h under nitrogen protection. The temperature was then lowered to 550℃, acetylene gas was introduced at a flow rate of 150 ml / min, and the mixture was kept at this temperature for 3 h. The mixture was then allowed to cool naturally to room temperature before being removed.

[0027] 3) The product from step 2 was soaked in an 8 wt% zirconium nitrate solution for 6 hours, then dried and placed in a tube furnace. Under nitrogen protection, the temperature was raised to 550°C and calcined for 6 hours. After cooling to room temperature, the product was taken out and crushed to obtain carbon fibers with a titanium carbide layer, a carbon layer and a zirconium carbide layer successively coated on the surface.

[0028] 4) Zirconia powder with an average particle size of 30 micrometers, silicon carbide powder with an average particle size of 30 micrometers, carbon fiber obtained in step 3, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 80:80:30:15:3, and the solid content is adjusted to 40wt%. The dispersed slurry is placed in a mold, dried, and hot-pressed for 30 minutes to set the shape. The hot-pressing temperature is 80℃ and the pressure is 32MPa. The set body is placed in a tube furnace and calcined at 1200℃ for 8 hours under nitrogen protection, then calcined at 2000℃ for 2 hours, and then annealed at 500℃ for 1 hour to obtain a short fiber rigid thermal insulation composite material.

[0029] Example 2:

[0030] 1) Take short-cut carbon fibers with a diameter of 8μm and a length of 2mm, disperse them in a mixed solution of acetone and tetrahydrofuran with a mass ratio of 1:1.5, then wash them 5 times with ethanol, and dry them to obtain pretreated carbon fibers.

[0031] 2) The pretreated carbon fiber and titanium metal powder with a particle size of 1000nm were ball-milled at a mass ratio of 100:15, with a ball-to-material ratio of 5:1, a rotation speed of 150r / min, for 6 hours. Then, the mixture was placed in a tube furnace and calcined at 1200℃ for 4 hours under nitrogen protection. The temperature was then lowered to 650℃, acetylene gas was introduced at a flow rate of 150ml / min, and the mixture was kept at this temperature for 0.5 hours. The mixture was then allowed to cool naturally to room temperature before being removed.

[0032] 3) The product from step 2 was soaked in a 12wt% zirconium nitrate solution for 3 hours, then dried and placed in a tube furnace. Under nitrogen protection, the temperature was raised to 650℃ and calcined for 4 hours. After cooling to room temperature, the product was taken out and crushed to obtain carbon fibers with a titanium carbide layer, a carbon layer and a zirconium carbide layer successively coated on the surface.

[0033] 4) Zirconia powder with an average particle size of 50 micrometers, silicon carbide powder with an average particle size of 50 micrometers, carbon fiber obtained in step 3, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 100:100:50:20:5, and the solid content is adjusted to 60wt%. The dispersed slurry is placed in a mold, dried, and hot-pressed for 30 minutes to set the shape. The hot-pressing temperature is 90℃ and the pressure is 32MPa. The set body is placed in a tube furnace and calcined at 1400℃ for 6 hours under nitrogen protection, then calcined at 2000℃ for 1 hour, and then annealed at 500-600℃ for 0.5 hours to obtain a short fiber rigid thermal insulation composite material.

[0034] Example 3:

[0035] 1) Take short-cut carbon fibers with a diameter of 6μm and a length of 2mm, disperse them in a mixed solution of acetone and tetrahydrofuran with a mass ratio of 1:1.2, then wash them 4 times with ethanol, and dry them to obtain pretreated carbon fibers.

[0036] 2) The pretreated carbon fiber and titanium metal powder with a particle size of 800 nm were ball-milled at a mass ratio of 100:12, with a ball-to-material ratio of 4:1, a rotation speed of 120 r / min, for 8 h. Then the mixture was placed in a tube furnace and calcined at 1100℃ for 5 h under nitrogen protection. The temperature was then lowered to 600℃, acetylene gas was introduced at a flow rate of 120 ml / min, and the mixture was kept at this temperature for 1 h. The mixture was then allowed to cool naturally to room temperature before being removed.

[0037] 3) The product from step 2 was soaked in a 10 wt% zirconium nitrate solution for 5 hours, then dried and placed in a tube furnace. Under nitrogen protection, the temperature was raised to 600°C and calcined for 5 hours. After cooling to room temperature, the product was taken out and crushed to obtain carbon fibers with a titanium carbide layer, a carbon layer and a zirconium carbide layer successively coated on the surface.

[0038] 4) Zirconia powder with an average particle size of 40 micrometers, silicon carbide powder with an average particle size of 40 micrometers, carbon fiber obtained in step 3, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 90:90:40:18:4, and the solid content is adjusted to 50 wt%. The dispersed slurry is placed in a mold, dried, and hot-pressed for 20 minutes to set the shape. The hot-pressing temperature is 85℃ and the pressure is 32 MPa. The set body is placed in a tube furnace and calcined at 1300℃ for 7 hours under nitrogen protection, then calcined at 2000℃ for 1 hour, and then annealed at 550℃ for 1 hour to obtain a short fiber rigid thermal insulation composite material.

[0039] Comparative Example 1 (without titanium metal modification)

[0040] 1) Take short-cut carbon fibers with a diameter of 6μm and a length of 2mm, disperse them in a mixed solution of acetone and tetrahydrofuran with a mass ratio of 1:1.2, then wash them 4 times with ethanol, and dry them to obtain pretreated carbon fibers.

[0041] 2) Place the pretreated carbon fiber in a tube furnace, heat it to 600℃ under nitrogen protection, introduce acetylene gas at a flow rate of 120ml / min, keep it at this temperature for 1 hour, and then let it cool naturally to room temperature before taking it out.

[0042] 3) The product from step 2 was soaked in a 10 wt% zirconium nitrate solution for 5 hours, then dried and placed in a tube furnace. Under nitrogen protection, the temperature was raised to 600°C and calcined for 5 hours. After cooling to room temperature, the product was taken out and crushed to obtain carbon fibers with a titanium carbide layer, a carbon layer and a zirconium carbide layer successively coated on the surface.

[0043] 4) Zirconia powder with an average particle size of 40 micrometers, silicon carbide powder with an average particle size of 40 micrometers, carbon fiber obtained in step 3, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 90:90:40:18:4, and the solid content is adjusted to 50 wt%. The dispersed slurry is placed in a mold, dried, and hot-pressed for 20 minutes to set the shape. The hot-pressing temperature is 85℃ and the pressure is 32 MPa. The set body is placed in a tube furnace and calcined at 1300℃ for 7 hours under nitrogen protection, then calcined at 2000℃ for 1 hour, and then annealed at 550℃ for 1 hour to obtain a short fiber rigid thermal insulation composite material.

[0044] Comparative Example 2 (without carbon coating)

[0045] 1) Take short-cut carbon fibers with a diameter of 6μm and a length of 2mm, disperse them in a mixed solution of acetone and tetrahydrofuran with a mass ratio of 1:1.2, then wash them 4 times with ethanol, and dry them to obtain pretreated carbon fibers.

[0046] 2) The pretreated carbon fiber and titanium metal powder with a particle size of 800nm ​​were ball-milled at a mass ratio of 100:12, with a ball-to-material ratio of 4:1, a rotation speed of 120r / min, and a ball-milling time of 8h. Then, the mixture was placed in a tube furnace and calcined at 1100℃ for 5h under nitrogen protection. After natural cooling to room temperature, the mixture was removed.

[0047] 3) The product from step 2 was soaked in a 10 wt% zirconium nitrate solution for 5 hours, then dried and placed in a tube furnace. Under nitrogen protection, the temperature was raised to 600°C and calcined for 5 hours. After cooling to room temperature, the product was taken out and crushed to obtain carbon fibers with a titanium carbide layer, a carbon layer and a zirconium carbide layer successively coated on the surface.

[0048] 4) Zirconia powder with an average particle size of 40 micrometers, silicon carbide powder with an average particle size of 40 micrometers, carbon fiber obtained in step 3, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 90:90:40:18:4, and the solid content is adjusted to 50 wt%. The dispersed slurry is placed in a mold, dried, and hot-pressed for 20 minutes to set the shape. The hot-pressing temperature is 85℃ and the pressure is 32 MPa. The set body is placed in a tube furnace and calcined at 1300℃ for 7 hours under nitrogen protection, then calcined at 2000℃ for 1 hour, and then annealed at 550℃ for 1 hour to obtain a short fiber rigid thermal insulation composite material.

[0049] Comparative Example 3 (without zirconium carbide coating)

[0050] 1) Take short-cut carbon fibers with a diameter of 6μm and a length of 2mm, disperse them in a mixed solution of acetone and tetrahydrofuran with a mass ratio of 1:1.2, then wash them 4 times with ethanol, and dry them to obtain pretreated carbon fibers.

[0051] 2) The pretreated carbon fiber and titanium metal powder with a particle size of 800 nm were ball-milled at a mass ratio of 100:12, with a ball-to-material ratio of 4:1, a rotation speed of 120 r / min, for 8 h. Then the mixture was placed in a tube furnace and calcined at 1100℃ for 5 h under nitrogen protection. The temperature was then lowered to 600℃, acetylene gas was introduced at a flow rate of 120 ml / min, and the mixture was kept at this temperature for 1 h. The mixture was then allowed to cool naturally to room temperature before being removed.

[0052] 3) Zirconia powder with an average particle size of 40 micrometers, silicon carbide powder with an average particle size of 40 micrometers, carbon fiber obtained in step 2, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 90:90:40:18:4, and the solid content is adjusted to 50 wt%. The dispersed slurry is placed in a mold, dried, and hot-pressed for 20 minutes to set the shape. The hot-pressing temperature is 85℃ and the pressure is 32 MPa. The set body is placed in a tube furnace and calcined at 1300℃ for 7 hours under nitrogen protection, then calcined at 2000℃ for 1 hour, and then annealed at 550℃ for 1 hour to obtain a short fiber rigid thermal insulation composite material.

[0053] Comparative Example 4 (without titanium metal modification and carbon coating)

[0054] 1) Take short-cut carbon fibers with a diameter of 6μm and a length of 2mm, disperse them in a mixed solution of acetone and tetrahydrofuran with a mass ratio of 1:1.2, then wash them 4 times with ethanol, and dry them to obtain pretreated carbon fibers.

[0055] 2) The product from step 1 was soaked in a 10 wt% zirconium nitrate solution for 5 hours, then dried and placed in a tube furnace. Under nitrogen protection, the temperature was raised to 600°C and calcined for 5 hours. After cooling to room temperature, the product was taken out and crushed to obtain carbon fibers with a titanium carbide layer, a carbon layer and a zirconium carbide layer successively coated on the surface.

[0056] 3) Zirconia powder with an average particle size of 40 micrometers, silicon carbide powder with an average particle size of 40 micrometers, carbon fiber obtained in step 2, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 90:90:40:18:4, and the solid content is adjusted to 50 wt%. The dispersed slurry is placed in a mold, dried, and hot-pressed for 20 minutes to set the shape. The hot-pressing temperature is 85℃ and the pressure is 32 MPa. The set body is placed in a tube furnace and calcined at 1300℃ for 7 hours under nitrogen protection, then calcined at 2000℃ for 1 hour, and then annealed at 550℃ for 1 hour to obtain a short fiber rigid thermal insulation composite material.

[0057] Comparative Example 5 (without carbon coating or zirconium carbide coating)

[0058] 1) Take short-cut carbon fibers with a diameter of 6μm and a length of 2mm, disperse them in a mixed solution of acetone and tetrahydrofuran with a mass ratio of 1:1.2, then wash them 4 times with ethanol, and dry them to obtain pretreated carbon fibers.

[0059] 2) The pretreated carbon fiber and titanium metal powder with a particle size of 800nm ​​were ball-milled at a mass ratio of 100:12, with a ball-to-material ratio of 4:1, a rotation speed of 120r / min, for 8 hours. Then the mixture was placed in a tube furnace and calcined at 1100℃ for 5 hours under nitrogen protection. It was then naturally cooled to room temperature and removed.

[0060] 3) Zirconia powder with an average particle size of 40 micrometers, silicon carbide powder with an average particle size of 40 micrometers, carbon fiber obtained in step 2, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 90:90:40:18:4, and the solid content is adjusted to 50 wt%. The dispersed slurry is placed in a mold, dried, and hot-pressed for 20 minutes to set the shape. The hot-pressing temperature is 85℃ and the pressure is 32 MPa. The set body is placed in a tube furnace and calcined at 1300℃ for 7 hours under nitrogen protection, then calcined at 2000℃ for 1 hour, and then annealed at 550℃ for 1 hour to obtain a short fiber rigid thermal insulation composite material.

[0061] Comparative Example 6 (Pure Carbon Fiber)

[0062] 1) Take short-cut carbon fibers with a diameter of 6μm and a length of 2mm, disperse them in a mixed solution of acetone and tetrahydrofuran with a mass ratio of 1:1.2, then wash them 4 times with ethanol, and dry them to obtain pretreated carbon fibers.

[0063] 2) Zirconia powder with an average particle size of 40 micrometers, silicon carbide powder with an average particle size of 40 micrometers, carbon fiber obtained in step 1, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 90:90:40:18:4, and the solid content is adjusted to 50 wt%. The dispersed slurry is placed in a mold, dried, and hot-pressed for 20 minutes to set the shape. The hot-pressing temperature is 85℃ and the pressure is 32 MPa. The set body is placed in a tube furnace and calcined at 1300℃ for 7 hours under nitrogen protection, then calcined at 2000℃ for 1 hour, and then annealed at 550℃ for 1 hour to obtain a short fiber rigid thermal insulation composite material.

[0064] Test data

[0065] The product performance in the embodiments and comparative examples of the present invention was tested, and the results are shown in Table 1.

[0066] Table 1

[0067]

[0068]

[0069] By adjusting the process in the comparative examples, it is intended to demonstrate the influence of each process parameter on product performance. The product prepared by the method of the present invention has good thermal insulation performance and good mechanical strength.

[0070] The comparison between the examples and Comparative Example 6 shows that the modification of carbon fibers in this invention greatly improves the mechanical properties of the product and also significantly enhances the thermal insulation performance. Comparative Example 1 shows that titanium metal modification of carbon fibers allows the metal to act as a catalyst during carbon deposition, promoting deposition and improving the deposition effect. It also partially forms titanium carbide hard alloy, increasing the strength of the carbon fibers. Comparative Examples 2 and 4 show that the carbon layer significantly promotes the formation of the zirconium carbide layer. Due to the high specific surface area of ​​the carbon layer, soluble zirconium salts can adhere to the surface, and zirconium carbide is formed during heating. Comparative Examples 3 and 5 show that zirconium carbide, as a material with high hardness and a high melting point, can prevent the loss of carbon fibers during subsequent high-temperature heating, improving the mechanical properties of the insulation material. Zirconium carbide has a high affinity for zirconium oxide and silicon carbide added to the material, which is beneficial for the dispersion of short fibers in the material, preventing agglomeration, thereby reducing thermal conductivity and improving mechanical properties.

[0071] Although the present invention has been described in detail through the above preferred embodiments, it should be understood that the above description should not be considered as a limitation of the present invention.

Claims

1. A preparation process for a short-fiber rigid thermal insulation composite material, characterized in that, The preparation process includes: 1) Take short-cut carbon fibers, disperse them in a mixed solution of acetone and tetrahydrofuran, wash and dry them to obtain pretreated carbon fibers; 2) Mix the pretreated carbon fiber and titanium metal nanopowder evenly, then place them in a tube furnace and calcine them at 1000-1200℃ under a protective atmosphere; cool down to 550-650℃, introduce acetylene gas, keep warm for a predetermined time, and cool to room temperature before taking them out. 3) The product from step 2 was immersed in a zirconium salt solution, dried, and then placed in a tube furnace. Under a protective atmosphere, it was heated to 550-650℃ and calcined. After cooling to room temperature, it was taken out and crushed to obtain carbon fibers with a titanium carbide layer, a carbon layer and a zirconium carbide layer successively coated on the surface. 4) Disperse zirconium oxide powder, silicon carbide powder, carbon fiber obtained in step 3, phenolic resin and silane coupling agent in ethanol, dry and hot press to set; place the set preform in a tube furnace, heat to 1200-2200℃ under a protective atmosphere and calcine, then cool to 500-600℃ for annealing to obtain short fiber rigid thermal insulation composite material.

2. The preparation process of the short fiber rigid thermal insulation composite material according to claim 1, characterized in that: In step 1, the short-cut carbon fibers have a diameter of 5-8 μm and a length of 1-2 mm; the mass ratio of acetone to tetrahydrofuran is 1:1-1.

5.

3. The preparation process of the short fiber rigid thermal insulation composite material according to claim 1, characterized in that: In step 2, the pretreated carbon fiber and titanium nanoparticles are mixed at a mass ratio of 100:10-15, and the titanium nanoparticles have a particle size of 500-1000 nm.

4. The preparation process of the short fiber rigid thermal insulation composite material according to claim 3, characterized in that: In step 2, the high-temperature calcination in the tubular furnace under nitrogen protection is carried out at a temperature of 1000-1200℃ for 4-6 hours; then the temperature is lowered to 550-650℃, acetylene gas is introduced, and the flow rate of acetylene gas is 100-150 ml / min, and the temperature is maintained for 0.5-3 hours.

5. The preparation process of the short fiber rigid thermal insulation composite material according to claim 1, characterized in that: In step 3, the zirconium salt solution is a zirconium nitrate solution with a concentration of 8-12 wt% and a soaking time of 3-6 h.

6. The preparation process of the short fiber rigid thermal insulation composite material according to claim 5, characterized in that: In step 3, the calcination temperature in the tubular furnace under nitrogen protection is 550-650℃, and the calcination time is 4-6h.

7. The preparation process of the short fiber rigid thermal insulation composite material according to claim 1, characterized in that: In step 4, zirconium oxide powder with an average particle size of 30-50 micrometers, silicon carbide powder with an average particle size of 30-50 micrometers, carbon fiber obtained in step 3, phenolic resin and silane coupling agent are mixed and dispersed in ethanol at a mass ratio of 80-100:80-100:30-60:15-20:3-5, and the solid content is adjusted to 40-60 wt%.

8. The preparation process of the short fiber rigid thermal insulation composite material according to claim 7, characterized in that: In step 4, the hot pressing temperature is 80-90℃, the hot pressing time is 10-30min, and the hot pressing pressure is 30-35MPa.

9. The preparation process of the short fiber rigid thermal insulation composite material according to claim 1, characterized in that: In step 4, the shaped preform is placed in a tube furnace and calcined at 1200-1400℃ for 6-8 hours under nitrogen protection, then calcined at 2000-2200℃ for 1-2 hours, and then annealed at 500-600℃ for 0.5-1 hours to obtain a short fiber rigid thermal insulation composite material.

10. A short-fiber rigid thermal insulation composite material, characterized in that: The material is prepared using the preparation process described in any one of claims 1-9.

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