A particle-reinforced polyimide composite and an ultrahigh pressure molding method

Abstract

The application discloses a kind of particle reinforced polyimide composite and ultra-high pressure forming method, belong to composite material technical field.The particle reinforced polyimide composite ultra-high pressure forming method provided by the application includes the following steps: (1) thermoplastic polyimide powder, nano filler and wear-resistant filler are mixed uniformly, to obtain mixed molding powder;(2) gas-permeable high-temperature isolation film is laid around the filler groove of ultra-high pressure forming mold;(3) the molding powder is placed in the forming mold, and hot-press forming is carried out;(4) the hot-press forming blank is loaded into post-processing tooling, high-temperature treatment is carried out in the oven, to obtain the particle reinforced polyimide composite.The particle reinforced polyimide composite prepared by the application is a high-performance resin-based composite material with high temperature resistance, low wear and high dimensional stability, and has wide application prospects in high-end manufacturing fields such as aerospace engine cold end wear parts.

Description

Technical Field

[0001] This application relates to a particle-reinforced polyimide composite material and an ultra-high pressure molding method, belonging to the field of composite material technology. Background Technology

[0002] Lightweight design, high energy efficiency, high reliability, and low cost are the main goals pursued in the development of aerospace vehicle structures and materials. Resin-based composite materials are widely used in aerospace structural components due to their high specific strength, specific modulus, and good processing characteristics. After more than 50 years of development, resin-based composite materials have evolved from early unsaturated polyester-based composites to epoxy, bismaleimide, cyanate ester, and polyimide resin-based composites, mainly moving towards high temperature resistance, load-bearing capacity, and multifunctional integration. Currently, foreign countries have developed a new generation of particle-reinforced polyimide-based composites with higher temperature resistance and superior basic mechanical properties. These composites are widely used in high-end manufacturing fields such as aero-engines, automotive engines, semiconductor devices, and high-temperature precision instruments due to their excellent properties such as high temperature resistance, low wear, and high dimensional stability, achieving significant commercial value. Domestically, the main material systems used were developed in the 1980s and lack competitiveness in terms of temperature resistance, friction and wear performance, and basic mechanical properties. Therefore, developing cutting-edge technologies in the field of high-temperature resistant resin-based composites, developing a new generation of high-temperature / low-wear resistant polyimide composites, and exploring ultra-high pressure molding methods for particle-reinforced polyimide composites are inevitable trends.

[0003] To achieve a balance of high temperature resistance, high dimensional stability, and low wear, a large proportion of rigid aromatic ring structures needs to be introduced into the main chain of polyimide resin molecules. This reduces the number of ether bonds or other flexible groups in the main chain while increasing the molecular weight of the thermoplastic resin system and the degree of crosslinking in the thermosetting resin system. However, these changes in molecular structure not only significantly alter the resin's rheological behavior, drastically reducing its flow properties and significantly increasing the molding pressure required for the composite material, but also significantly increase the resin's glass transition temperature, widening the molding temperature range of the composite material and further increasing the requirements for molding temperature. High temperature and high pressure pose significant challenges to the molding of polyimide composites. Therefore, developing an ultra-high pressure molding method is crucial to fully realizing the engineering application potential of high-performance particle-reinforced polyimide composites. Summary of the Invention

[0004] The technical problem solved by this application is: addressing the issue of poor processability of high-temperature resistant, low-wear, and high-dimensional-stability polyimide composite materials, this invention provides a particle-reinforced polyimide composite material and an ultra-high pressure molding method.

[0005] The technical solution provided in this application is as follows:

[0006] A high-pressure molding method for particle-reinforced polyimide composite materials is a molding method that includes multiple steps such as powder blending, mold pretreatment, hot pressing, and post-treatment.

[0007] A method for ultra-high pressure molding of particle-reinforced polyimide composite materials includes the following steps:

[0008] (1) The thermoplastic polyimide powder, nanofiller and wear-resistant filler are mixed evenly to obtain a mixed molding powder;

[0009] (2) Lay a high-temperature insulating membrane around the filling groove of the ultra-high pressure forming mold;

[0010] (3) Place the above-mentioned mixed molding powder in a molding mold and perform hot pressing to obtain a hot-pressed blank;

[0011] (4) The hot-pressed blank is loaded into the post-processing fixture and treated at high temperature in the oven to obtain the particle-reinforced polyimide composite material.

[0012] In step (1) above, the average particle size of the thermoplastic polyimide powder is 10μm to 75μm and the molecular weight is not less than 5000; the glass transition temperature of the mixed molding powder is 250 to 400℃.

[0013] In step (1) above, the proportions of each component in the mixed molding powder are as follows: by weight, the proportions of each raw material are: 65 to 84.5 parts of polyimide molding powder, 15 to 30 parts of wear-resistant filler (graphite filler), and 0.5 to 5 parts of nano filler (graphene oxide filler).

[0014] The polyimide molding powder in the mixed molding powder includes either homemade polyimide molding powder or commercially available polyimide molding powder.

[0015] The commercially available polyimide molding powder is designated as SP-1, SP-21, TS-1, TS-1-1, or SCP-5000.

[0016] The wear-resistant filler is graphite powder.

[0017] The nanofiller is graphene oxide powder.

[0018] The graphite powder has a particle size of 2μm to 10μm, and the graphene oxide powder has a particle size of 0.2μm to 10μm.

[0019] In step (2) above, the method for laying the high-temperature isolation film in the mold is as follows: a high-temperature release agent is applied to both sides of the high-temperature isolation film, ventilation holes are made on the surface of the isolation film, the isolation film is cut according to the size of the filling groove, and the isolation film is attached to the surface of the filling groove. The isolation film surface is evenly slit, with the length of a single slit between 10 and 50 mm, and the slit density on the isolation film surface should not be less than 500 slits / m². 2 .

[0020] The decomposition temperature of the high-temperature release agent should be higher than 450℃.

[0021] The decomposition temperature of the high-temperature isolation membrane should be higher than 450°C.

[0022] The surface of the filling groove includes all surfaces in the molding mold that are in direct contact with the mixed molding powder. For the same filling groove surface composed of different mold modules, a high-temperature isolation film of appropriate size should be made and attached separately.

[0023] The process of attaching the release film to the surface of the packing groove should ensure that the release film is completely adhered to the surface of the packing groove, and there should be no visible bubbles or creases.

[0024] In step (3) above, the hot pressing method is as follows: the initial temperature is room temperature, the initial pressure is 50-100 MPa, the heating rate is 3-20℃ / min, the equilibrium temperature is 30-80℃ higher than the glass transition temperature of the thermoplastic polyimide powder, the equilibrium pressure is 100-200 MPa, and the equilibrium time is 0.5-1h.

[0025] In step (4) above, the post-processing method can be as follows: the initial temperature is room temperature to 80°C, the heating rate is 3 to 20°C / min, the equilibrium temperature is 50°C to 100°C higher than the glass transition temperature of the thermoplastic polyimide powder, and the equilibrium time is 2 to 10 hours.

[0026] Invention Principle: This invention provides a method for ultra-high pressure molding of particle-reinforced polyimide composite materials. First, thermoplastic polyimide powder, graphene oxide powder, and high-mesh graphite powder are mixed uniformly to obtain a mixed molding powder. Simultaneously, a high-temperature isolation film is laid around the filler groove of the ultra-high pressure molding mold. Then, the molding powder is placed in the molding mold and hot-pressed. Finally, the hot-pressed blank is loaded into a post-processing fixture and treated at high temperature in an oven to obtain the particle-reinforced polyimide composite material.

[0027] Thorough mixing of all components ensures the stability of the polyimide composite product and effectively suppresses stress concentration caused by differences in the coefficients of thermal expansion and thermal conductivity of different components during high-temperature and high-pressure molding. The high-temperature isolation membrane around the filler groove reduces the contact area between the mixed molding powder and the hot-pressing mold, preventing damage to the particle-reinforced polyimide composite blank during the demolding process. The post-processing aims to heat the blank above its glass transition temperature, further reducing internal stress through molecular chain segment movement and improving the product yield in subsequent machining processes.

[0028] This invention uses a high-temperature resistant isolation membrane to eliminate the problem of difficult demolding during the ultra-high pressure molding process of particle-reinforced polyimide composite materials. At the same time, it uses a post-treatment method to eliminate the internal stress concentration phenomenon caused by the ultra-high pressure molding process of particle-reinforced polyimide composite materials. Detailed Implementation

[0029] This invention provides a method for ultra-high pressure molding of particle-reinforced polyimide composite materials. First, thermoplastic polyimide powder, nanofiller and wear-resistant filler are mixed evenly to obtain a mixed molding powder. After laying a high-temperature isolation film around the filler groove of the ultra-high pressure molding mold, the above molding powder is placed in the molding mold and hot-pressed. The hot-pressed blank is loaded into the post-processing fixture and treated at high temperature in an oven to obtain the particle-reinforced polyimide composite material.

[0030] Example 1

[0031] (1) Preparation of mixed molding powder

[0032] 84.5 g of SP-1 polyimide powder, 15 g of graphite powder with a particle size distribution between 2 and 10 μm, and 0.5 g of graphene oxide powder with a particle size distribution between 0.2 and 10 μm were placed in a beaker and stirred for 5 min. The resulting mixture was then homogenized in a homogenizer to obtain a mixed molding powder. The glass transition temperature of the mixed molding powder was 350 °C.

[0033] (2) Laying high-temperature insulating film

[0034] Apply PMR room temperature curing release agent to both sides of the breathable high-temperature release film. After the release agent dries, apply the next coat, for a total of three coats. Cut the high-temperature release film according to the size of the filler groove. Use a scriber to score the surface of the release film, with each score being 10-50 mm in length and a score density of 800 scores / m². 2 A breathable high-temperature insulating membrane is obtained. The cut breathable high-temperature insulating membrane is attached to the surface of the filling groove, ensuring that the membrane is wrinkle-free and creased, and the air between the membrane and the mold is squeezed out.

[0035] (3) Hot pressing

[0036] The mixed molding powder is evenly placed in the hot press mold. After the mold is closed, an initial pressure of 100 MPa is applied. The hot press mold is heated from room temperature to 420°C at a rate of 3°C / min, and the pressure is increased from 100 MPa to 200 MPa. The temperature is maintained for 1 hour.

[0037] (4) Post-processing

[0038] The hot-pressed blank is loaded into the post-processing fixture and placed in a high-temperature oven. The post-processing fixture is heated from room temperature to 450°C at a rate of 3°C / min, kept at this temperature for 10 hours, cooled to room temperature, and then demolded to obtain a particle-reinforced polyimide composite material.

[0039] Example 2

[0040] (1) Preparation of mixed molding powder

[0041] 68g of TS-1 polyimide powder, 30g of graphite powder with a particle size distribution between 2 and 10 μm, and 2g of graphene oxide powder with a particle size distribution between 0.2 and 10 μm were placed in a beaker and stirred for 5 minutes. The resulting molding powder was then homogenized in a homogenizer to obtain a mixed molding powder. The glass transition temperature of the mixed molding powder was 300℃.

[0042] (2) Laying high-temperature insulating film

[0043] Apply PMR room temperature curing release agent to both sides of the breathable high-temperature isolation membrane. After the release agent dries, apply the next coat, for a total of three coats. Cut the breathable high-temperature isolation membrane according to the size of the filler groove. Use a scribing knife to score the surface of the isolation membrane, with the length of each score being 10-50 mm, and the score density on the isolation membrane surface being 800 scores / m. 2 A breathable high-temperature insulating membrane is obtained. This membrane is then attached to the surface of the filling groove, ensuring it is wrinkle-free and creased, thus squeezing out any air between the membrane and the mold.

[0044] (3) Hot pressing

[0045] The mixed molding powder is evenly placed in the hot press mold. After the mold is closed, an initial pressure of 50 MPa is applied. The hot press mold is heated from room temperature to 380°C at a rate of 20°C / min, and the pressure is increased from 50 MPa to 100 MPa. The temperature is maintained for 0.5 hours.

[0046] (4) Post-processing

[0047] The hot-pressed blank is loaded into the post-processing fixture and placed in a high-temperature oven. The post-processing fixture is heated from room temperature to 390°C at a rate of 20°C / min, kept at that temperature for 2 hours, cooled to room temperature, and demolded to obtain a particle-reinforced polyimide composite material.

[0048] Example 3

[0049] (1) Preparation of mixed molding powder

[0050] 75g of TS-1 polyimide powder, 20g of graphite powder with a particle size distribution between 2 and 10 μm, and 5g of graphene oxide powder with a particle size distribution between 0.2 and 10 μm were placed in a beaker and stirred for 5 minutes. The resulting molding powder was then homogenized in a homogenizer to obtain a mixed molding powder. The glass transition temperature of the mixed molding powder was 260℃.

[0051] (2) Laying high-temperature insulating film

[0052] Apply PMR room temperature curing release agent to both sides of the breathable high-temperature release film. After the release agent dries, apply the next coat, for a total of three coats. Cut the high-temperature release film according to the size of the filler groove. Use a scriber to score the surface of the release film, with each score being 10-50 mm in length and a score density of 800 scores / m². 2 A breathable, high-temperature insulating membrane is obtained. The insulating membrane is attached to the surface of the filling groove, ensuring it is wrinkle-free and creased, and the air between the insulating membrane and the mold is squeezed out.

[0053] (3) Hot pressing

[0054] The mixed molding powder was evenly placed in the hot press mold. After the mold was closed, an initial pressure of 80 MPa was applied, and the hot press mold was heated from room temperature to 290°C at a rate of 10°C / min and kept at that temperature for 0.75 h.

[0055] (4) Post-processing

[0056] The hot-pressed blank is loaded into the post-processing fixture and placed in a high-temperature oven. The post-processing fixture is heated from room temperature to 310°C at a rate of 10°C / min, kept at that temperature for 5 hours, cooled to room temperature, and demolded to obtain a particle-reinforced polyimide composite material.

[0057] Example 4

[0058] The difference from Example 1 is that the hot pressing equilibrium temperature is 430°C.

[0059] Example 5

[0060] The difference from Example 1 is that the hot pressing equilibrium temperature is 380°C and the post-processing equilibrium temperature is 410°C.

[0061] Example 6

[0062] The difference from Example 1 is that the hot pressing equilibrium temperature is 380°C and the post-processing equilibrium temperature is 400°C.

[0063] Example 7

[0064] The difference from Example 1 is that: after the mold is closed, an initial pressure of 100 MPa is applied, and the hot press mold is heated from room temperature to 420°C at a rate of 3°C / min, and the pressure is increased from 100 MPa to 150 MPa.

[0065] Example 8

[0066] The difference from Example 1 is that: after the mold is closed, an initial pressure of 100 MPa is applied, and the hot press mold is heated from room temperature to 420°C at a rate of 3°C / min, while the pressure is kept constant at 100 MPa.

[0067] Example 9

[0068] The difference from Example 1 is that: after the mold is closed, an initial pressure of 50 MPa is applied, and the hot press mold is heated from room temperature to 420°C at a rate of 3°C / min, and the pressure is increased from 50 MPa to 200 MPa.

[0069] Example 10

[0070] The difference from Example 1 is that: after the mold is closed, an initial pressure of 80 MPa is applied, and the hot press mold is heated from room temperature to 420°C at a rate of 3°C / min, and the pressure is increased from 80 MPa to 200 MPa.

[0071] Comparative Example 1

[0072] (1) Preparation of mixed molding powder

[0073] 84.5g of SP-1 polyimide powder, 15g of graphite powder with a particle size distribution between 2 and 10μm and 0.5g of graphene oxide powder with a particle size distribution between 0.2 and 10μm were placed in a beaker and stirred for 5 minutes. The mixed molding powder was then placed in a homogenizer and mixed evenly to obtain the mixed molding powder.

[0074] (2) Laying high-temperature insulating film

[0075] Apply PMR room temperature curing release agent to both sides of the breathable high temperature isolation film. After the release agent dries, apply the next layer. Apply a total of three layers. Cut the high temperature isolation film according to the size of the filling groove. Attach the isolation film to the surface of the filling groove, ensuring that the isolation film is wrinkle-free and creased. Squeeze out the air between the isolation film and the mold.

[0076] (3) Hot pressing

[0077] The mixed molding powder was evenly placed in the hot press mold. After the mold was closed, an initial pressure of 20 MPa was applied. The hot press mold was heated from room temperature to 420°C at a rate of 3°C / min, and the pressure was kept constant at 20 MPa for 1 hour.

[0078] (4) The hot-pressed blank is loaded into the post-processing fixture and placed in a high-temperature oven. The post-processing fixture is heated from room temperature to 450°C at a rate of 3°C / min, kept at the temperature for 10 hours, cooled to room temperature, and demolded to obtain particle-reinforced polyimide composite material.

[0079] Comparative Example 2

[0080] (1) Preparation of mixed molding powder

[0081] 68g of TS-1 polyimide powder, 30g of graphite powder with a particle size distribution between 2 and 10 μm, and 2g of graphene oxide powder with a particle size distribution between 0.2 and 10 μm were placed in a beaker and stirred for 5 minutes. The resulting molding powder was then homogenized in a homogenizer to obtain a mixed molding powder. The glass transition temperature of the mixed molding powder was 300℃.

[0082] (2) Laying high-temperature insulating film

[0083] A PMR room temperature curing release agent was applied to both sides of the high-temperature release film. After the release agent dried, another coat was applied, for a total of three coats. The release film was cut to size according to the dimensions of the filling groove and then attached to the surface of the filling groove, ensuring the release film was wrinkle-free and creased. Air was squeezed out between the release film and the mold. The difference from Example 2 is that the release film surface was not treated to allow air to pass through.

[0084] (3) Hot pressing

[0085] The mixed molding powder is evenly placed in the hot press mold. After the mold is closed, an initial pressure of 50 MPa is applied. The hot press mold is heated from room temperature to 380°C at a rate of 20°C / min, and the pressure is increased from 50 MPa to 100 MPa. The temperature is maintained for 0.5 hours.

[0086] (4) The hot-pressed blank is loaded into the post-processing fixture and placed in a high-temperature oven. The post-processing fixture is heated from room temperature to 390°C at a rate of 20°C / min, kept at the temperature for 2 hours, cooled to room temperature, and demolded to obtain particle-reinforced polyimide composite material.

[0087] Comparative Example 3

[0088] (1) Preparation of mixed molding powder

[0089] 75g of TS-1 polyimide powder, 20g of graphite powder with a particle size distribution between 2 and 10 μm, and 5g of graphene oxide powder with a particle size distribution between 0.2 and 10 μm were placed in a beaker and stirred for 5 minutes. The resulting molding powder was then homogenized in a homogenizer to obtain a mixed molding powder. The glass transition temperature of the mixed molding powder was 260℃.

[0090] (2) Laying high-temperature insulating film

[0091] Apply PMR room temperature curing release agent to both sides of the breathable high temperature isolation film. After the release agent dries, apply the next layer. Apply a total of three layers. Cut the high temperature isolation film according to the size of the filling groove. Attach the isolation film to the surface of the filling groove, ensuring that the isolation film is wrinkle-free and creased. Squeeze out the air between the isolation film and the mold.

[0092] (3) Hot pressing

[0093] The mixed molding powder was evenly placed in the hot press mold. After the mold was closed, an initial pressure of 80 MPa was applied, and the hot press mold was heated from room temperature to 290°C at a rate of 10°C / min and kept at that temperature for 0.75 h.

[0094] Comparative Example 4

[0095] The difference from Example 1 is that the hot pressing equilibrium temperature is 360°C.

[0096] Comparative Example 5

[0097] The difference from Example 1 is that the hot pressing equilibrium temperature is 470°C.

[0098] Comparative Example 6

[0099] The difference from Example 1 is that after the hot press mold is heated from room temperature to 420°C, the pressure is reduced from 100MPa to 50MPa and kept at that temperature for 1 hour.

[0100] Comparative Example 7

[0101] The difference from Example 1 is that an initial pressure of 20 MPa is applied after mold closing.

[0102] The porosity of the particle-reinforced polyimide composites prepared in different embodiments and comparative examples was observed by metallography, and their density was calculated. The test results are shown in Table 1.

[0103] Table 1. Test results of interfacial bonding performance of micro-debonded samples

[0104]

[0105]

[0106] As can be seen from the table, Examples 1, 2 and 3 can all control the porosity of the particle-reinforced polyimide composite material to within 3%, achieving high-quality molding.

[0107] Comparative Example 1 and Example 1 have the same component proportions. The initial pressure and equilibrium pressure during hot pressing were both adjusted from 100 MPa to 200 MPa. The porosity of the prepared particle-reinforced polyimide composite material was as high as 6.5%, indicating that such particle-reinforced polyimide composite materials with high temperature resistance, low wear and high dimensional stability require high molding pressure.

[0108] Comparative Example 2 and Example 2 have the same component proportions, but the isolation membrane attached to the surface of the mold filling groove has no vent holes. The porosity of the prepared particle-reinforced polyimide composite material is as high as 3.1%, indicating that such high-temperature resistant, low-wear, and high-dimensional stability particle-reinforced polyimide composite material requires venting channels during hot pressing. Pre-setting venting holes by scoring on the isolation membrane is one of the key steps to ensure high-quality molding.

[0109] Comparative Example 3 and Example 3 had the same proportions of each component, but no post-processing. The porosity of the prepared particle-reinforced polyimide composite material was as high as 3.3%, indicating that such high-temperature resistant, low-wear, and high-dimensionally stable particle-reinforced polyimide composite materials need to be subjected to high-temperature treatment after molding. The post-processing plays an important role in controlling the porosity of the composite material.

[0110] As can be seen from the table, the only difference between Examples 1 and 4 is the hot-pressing equilibrium temperature. When the hot-pressing equilibrium temperature is 420℃ and 430℃, the porosity of the prepared particle-reinforced polyimide composites is less than 0.5%. In Examples 5 and 6, the hot-pressing equilibrium temperature and the post-treatment equilibrium temperature are adjusted simultaneously, and the porosity of the prepared particle-reinforced polyimide composites is still less than 3%. However, in Comparative Examples 4 and 5, when the hot-pressing equilibrium temperature is adjusted to 360℃ and 470℃ respectively, the porosity of the prepared particle-reinforced polyimide composites is 11.7%, and the molding quality is significantly reduced. This indicates that both the thermoforming equilibrium temperature and the post-treatment equilibrium temperature can be finely adjusted within a certain range. The basic trend is that the higher the temperature, the better the molding quality. When the temperature is too low, the flowability of the polyimide molding powder is poor, and the pores formed during the molding process are difficult to be effectively discharged through the full flow of the resin, resulting in poor molding quality of the composite material. When the temperature is too high, the polyimide molding powder can reach a high degree of oxidation in a short time, which restricts the further movement of the molecular chains and also affects the molding quality of the composite material.

[0111] As can be seen from the table, Examples 1, 7, and 8 differ only in the pressure applied after reaching the hot-pressing equilibrium temperature. When the applied pressure is 200 MPa, 150 MPa, and 100 MPa, the porosity of the prepared particle-reinforced polyimide composites is less than 3%. Examples 1, 9, and 10 differ only in the clamping pressure. When the applied pressure is 100 MPa, 50 MPa, and 80 MPa, the porosity of the prepared particle-reinforced polyimide composites is less than 1%. However, in Comparative Example 6, when the pressure applied after reaching the hot-pressing equilibrium temperature is changed to 50 MPa, the porosity of the prepared particle-reinforced polyimide composite is as high as 4.1%. In Comparative Example 7, when the clamping pressure is changed to 20 MPa, the porosity of the prepared particle-reinforced polyimide composite is as high as 9.5%, and the molding quality is significantly reduced. This indicates that high-quality molding of high molecular weight polyimide molding powder requires high clamping pressure and molding pressure. When the clamping pressure is low, the molding powder is difficult to compact, resulting in excessively high initial porosity. When the molding pressure is low, the air in the pores of the composite material cannot be fully expelled. Both of these factors will lead to excessively high porosity of the composite material after molding.

[0112] The present application has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present application. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and implementation methods of the present application without departing from the spirit and scope of the present application, and all such modifications and improvements fall within the scope of the present application. The scope of protection of the present application is determined by the appended claims.

[0113] The contents not described in detail in this application specification are common knowledge to those skilled in the art.

Claims

1. A method for ultra-high pressure molding of particle-reinforced polyimide composite materials, characterized in that: include Thermoplastic polyimide powder, nanofiller and wear-resistant filler are mixed evenly to obtain a mixed molding powder; After laying a breathable high-temperature isolation membrane around the filler groove of the ultra-high pressure molding mold, the molding powder is placed in the molding mold and hot-pressed to obtain a blank. The blank is subjected to high-temperature post-treatment to obtain a particle-reinforced polyimide composite material; The nanofiller is graphene oxide powder; the wear-resistant filler is graphite powder. The average particle size of the thermoplastic polyimide powder is 10 μm to 75 μm, the particle size of the graphene oxide powder is 0.2 μm to 10 μm, and the particle size of the graphite powder is 2 μm to 10 μm. The method for laying the breathable high-temperature isolation membrane is as follows: a high-temperature release agent is applied to both sides of the breathable high-temperature isolation membrane, the breathable high-temperature isolation membrane is cut according to the size of the filling groove, and the breathable high-temperature isolation membrane is attached to the surface of the filling groove, so that the breathable high-temperature isolation membrane is completely attached to the surface of the filling groove. The surface of the breathable high-temperature insulating membrane should have evenly distributed slits, with the length of each slit ranging from 10 to 50 mm. The slit density on the surface of the breathable high-temperature insulating membrane should not be less than 500 slits / m. 2 ; The hot pressing conditions are as follows: initial temperature is room temperature, initial pressure is 50~100MPa, heating rate is 3~20℃ / min, equilibrium temperature is 30~80℃ higher than the glass transition temperature of thermoplastic polyimide powder, equilibrium pressure is 100~200MPa, and equilibrium time is 0.5~1h.

2. The ultra-high pressure molding method for particle-reinforced polyimide composite materials according to claim 1, characterized in that: The polyimide powder comprises 65 to 84.5 parts by weight, the wear-resistant filler comprises 15 to 30 parts, and the nano filler comprises 0.5 to 5 parts.

3. The ultra-high pressure molding method for particle-reinforced polyimide composite materials according to claim 1, characterized in that: The decomposition temperature of the high-temperature release agent is higher than the equilibrium temperature of hot pressing and high-temperature post-treatment; the decomposition temperature of the high-temperature release film is higher than the equilibrium temperature of hot pressing and high-temperature post-treatment.

4. The ultra-high pressure molding method for particle-reinforced polyimide composite materials according to claim 1, characterized in that: The conditions for the high-temperature post-treatment are as follows: the initial temperature is room temperature, the heating rate is 3~20℃ / min, the equilibrium temperature is 50℃~100℃ higher than the glass transition temperature of the thermoplastic polyimide powder, and the equilibrium time is 2~10h.

5. A method for ultra-high pressure molding of particle-reinforced polyimide composite materials according to claim 1 or 4, characterized in that: The equilibrium temperature of the high-temperature post-treatment is 10℃~30℃ higher than the equilibrium temperature of hot pressing.

6. A particle-reinforced polyimide composite material, characterized in that: The particle-reinforced polyimide composite material is prepared by an ultra-high pressure molding method according to any one of claims 1-5.

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