Preparation method of high-temperature-resistant and high-thermal-conductivity composite material and application thereof

Abstract

This invention relates to a method for preparing a high-temperature resistant and high-thermal-conductivity composite material and its application, comprising the following steps: surface treatment of mesophase pitch-based carbon fiber (MPCF) and deposition of a polysilazane (PSZ) coating; impregnation of the surface-treated MPCF with a silane-modified polyimide (SAPI) resin solution, followed by vacuum degassing to prepare a unidirectional prepreg; placement of the prepreg in a zoned temperature-controlled mold, and step-heat-press curing under vacuum to form a fiber volume fraction gradient structure; and post-treatment of the molded composite material by electron beam irradiation curing. The composite material obtained by this invention exhibits an axial thermal conductivity ≥140 W / m·K and a flexural strength retention rate ≥80% under vacuum conditions at 300℃; after 100 thermal cycles from -196℃ to +300℃, the thermal conductivity decreases by ≤5%; and the density is ≤1.9 g / cm³. 3 Total mass loss (TML) < 0.5% (300℃ / 1000h).

Description

Technical Field

[0001] This invention belongs to the field of polymer-based composite materials, specifically relating to a method for preparing a high-temperature resistant and high-thermal-conductivity composite material and its application. It is a composite material that combines high-temperature resistance (≥350℃ for long-term use) and high thermal conductivity (≥150W / m·K), and is suitable for aerospace and other fields where long-term high-temperature service is required. Background Technology

[0002] With the rapid development of aerospace technology, the power density of spacecraft energy systems continues to rise, making thermal management a core challenge for ensuring the long-term stable operation of equipment. Currently, space heat dissipation mainly relies on thermal radiation mechanisms, and the performance of thermal control materials directly determines heat dissipation efficiency and reliability. Existing thermal control material systems can be divided into two main categories: metal-based composite materials (such as aluminum-based materials) and polymer-based composite materials (such as polyimide-based materials). Although aluminum-based materials have high thermal conductivity, they are prone to softening at high temperatures above 300°C and have a high density (>2.7 g / cm³). 3 The limitations of conventional materials make it difficult to meet lightweight requirements. While polymer-based materials (such as traditional polyimide) offer advantages in terms of lightness and corrosion resistance, their thermal conductivity is generally below 50 W / m·K, and their temperature resistance is insufficient (decomposition temperature <300℃). During long-term operation in orbit, they are prone to releasing volatiles due to thermal decomposition, contaminating precision optical components. Furthermore, existing materials exhibit poor interfacial stability under extreme thermal cycling (e.g., -180℃ to +300℃), and carbon fibers are prone to debonding from the matrix, leading to a sharp decline in thermal conductivity and mechanical properties. These shortcomings severely restrict the reliability and heat dissipation efficiency of spacecraft in long-term high-temperature service environments. To address this issue, CN201310671420A proposed a high thermal conductivity nylon composite material, which improves thermal conductivity (>2.7 W / m·K) by adding carbon nanotubes and graphite. However, its matrix temperature resistance only reaches 110℃, making it unsuitable for long-term high-temperature environments of 300℃. Another patent, CN118638379B, developed a multi-component composite high thermal conductivity filler thermal interface material, which improves thermal conductivity through composite ceramics and carbon-based fillers. However, it did not solve the problems of oxidation resistance and thermal expansion mismatch under vacuum irradiation, leading to increased interfacial thermal resistance at high temperatures. While these technological attempts have partially improved performance, none have achieved synergistic optimization of high thermal conductivity, high temperature resistance, lightweight, and space environment stability. The crucial compatibility issue between high-temperature resistant resins and high thermal conductivity fibers remains unresolved, failing to meet the future spacecraft's requirements for lightweight and long-life heat dissipation systems.

[0003] This invention aims to provide a method for preparing and applying high-temperature resistant and high-thermal-conductivity composite materials. By optimizing the fiber interface and designing a space-adaptive process, it solves the heat dissipation problem of high-energy-density satellite energy systems, breaks through the bottlenecks of existing thermal control materials in terms of high-temperature stability, thermal conductivity, lightweighting and space environment compatibility, and meets the requirements for long-term on-orbit (>5 years) and rapid heat dissipation at high temperatures (300°C). Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a method for preparing high-temperature resistant and high thermal conductivity composite materials and their applications, so as to overcome the bottlenecks of existing thermal control materials in terms of high-temperature stability, thermal conductivity, lightweight and space environment compatibility, and realize their application in long-term high-temperature space service environments.

[0005] The above objectives can be achieved through the following innovative technical solutions:

[0006] This invention provides a method for preparing a high-temperature resistant and high-thermal-conductivity composite material, comprising the following steps:

[0007] S1. Impregnate pitch-based carbon fiber (MPCF) in polysilazane (PSZ) solution, remove and cure to obtain surface-treated pitch-based carbon fiber;

[0008] S2. A prepreg is prepared by hot-melt method, which involves combining surface-treated pitch-based carbon fibers with an adhesive film. The adhesive film is prepared by hot-melt method using silane-modified polyimide.

[0009] S3. The prepreg and the polyimide film modified with silane are unidirectionally laid up, and the surface prepreg layer, the core prepreg layer and the surface prepreg layer are laid up in sequence to obtain a preform consisting of the surface layer, the core and the surface layer arranged in sequence; the surface prepreg layer is obtained by directly laying up the prepreg, and the core prepreg layer is obtained by alternately laying up the film and the prepreg, and the core prepreg has film on both sides.

[0010] S4. The preform is subjected to step-by-step heating and hot-pressing curing to obtain the high-temperature resistant and high-thermal-conductivity composite material.

[0011] In one embodiment of the present invention, in step S1, the diameter of the pitch-based carbon fiber (MPCF) is 14±2 μm. The axial thermal conductivity of the pitch-based carbon fiber (MPCF) is ≥600 W / m·K.

[0012] In one embodiment of the present invention, in step S1, before depositing the polysilazane (PSZ) interface layer, the pitch-based carbon fiber (MPCF) is subjected to high temperature (400°C) vacuum treatment to remove the surface protective layer.

[0013] In one embodiment of the present invention, in step S1, the polysilazane (PSZ) content in the solution is 2-10 wt%. The impregnation time is 25-35 min, preferably 30 min.

[0014] In one embodiment of the present invention, in step S1, the curing temperature is 115℃-135℃ and the time is 0.5-2h.

[0015] As one embodiment of the present invention, the surface-treated pitch-based carbon obtained in step S1 is coated with polysilazane (PSZ) to form a polysilazane (PSZ) interface layer; the thickness of the polysilazane (PSZ) interface layer is 30-100 nm.

[0016] In one embodiment of the present invention, the prepreg obtained in step S2 has a volume fraction of 50-70% for pitch-based carbon fibers, preferably 62±2%, and the fibers are axially aligned.

[0017] In one embodiment of the present invention, in step S2, the adhesive film is prepared by hot-melt method from silanyl acetylenite-modified polyimide to a concentration of 30-90 g / m³. 2 The adhesive film.

[0018] In one embodiment of the present invention, in step S3, the thickness of the surface prepreg layer is 5%-20% of the preform thickness; the thickness of the prepreg in the core prepreg layer is 10%-30% of the preform thickness; the remainder is the adhesive film in the core prepreg. Adding the adhesive film to the core prepreg layer can reduce the fiber volume fraction after the core prepreg has cured.

[0019] In one embodiment of the present invention, in step S3, the alternation of the ply layers is performed 1-5 times. For example, if the total number of ply layers is 11 (…), then… Figure 1 The structure consists of layers 1-3 and 9-11 as surface prepreg, and layers 4-8 as core prepreg (with layers 4-5 and 7-8 being film, and layer 6 being prepreg, alternating once). The total number of layers is 17. Figure 2 Layers 1-5 and 13-17 are surface prepreg, and layers 6-12 are core prepreg (of which layers 6, 8, 10, and 12 are film, and layers 7, 9, and 11 are prepreg, alternating 3 times).

[0020] As one embodiment of the present invention, in step S4, during the step-heating hot-pressing curing process, the temperature changes are as follows: the first temperature is raised to 80-100℃ and then kept at that temperature for 1-2 hours; the second temperature is raised to 130-150℃ and then kept at that temperature for 1-2 hours; the third temperature is raised to 180-220℃ and then kept at that temperature for 1-3 hours; and the fourth temperature is raised to 340-370℃ and then kept at that temperature for 2-5 hours.

[0021] The pressure changes are as follows: after the first heating, the contact pressure is increased and the temperature is maintained; after the third heating, the pressure is increased to 0.5-1 MPa and the temperature is maintained; after maintaining the temperature, the pressure is increased to 4-6 MPa, and the fourth heating begins.

[0022] By controlling the resin gel state through staged heating and pressurization, small molecules in the resin gradually volatilize during the first and second heating stages, at which point no chemical reaction occurs. Upon further heating to 180-220℃, the silanyl groups begin prepolymerization, and the intercalated film gradually forms a three-dimensional network structure, providing some support. As the reaction releases heat, heat accumulates inside the composite material, with the internal resin layer exhibiting a higher degree of reaction than the surface. Pressurization following prepolymerization at 180-220℃ maintains a certain degree of prepolymerization in the internal resin layer, providing some support. The inner layer of the composite material maintains a high volume fraction of resin, while the surface resin has a lower degree of prepolymerization, resulting in relatively high resin fluidity. Some resin is extruded under pressure, leading to a higher fiber volume content on the surface layer, achieving a gradient distribution of fiber fraction in the composite material.

[0023] In one embodiment of the present invention, in step S2, the fiber volume fraction in the obtained high-temperature resistant and high-thermal-conductivity composite material is 64-80% in the surface region and 45-60% in the core region. The surface prepreg mainly forms the surface region, and the core prepreg mainly forms the core region. The gradient transition zone formed between the surface layer and the core accounts for 20-50% of the material thickness.

[0024] The present invention also provides a high-temperature resistant and high-thermal-conductivity composite material obtained by the preparation method described above. The composite material exhibits an axial thermal conductivity ≥140 W / m·K and a flexural strength retention rate ≥80% under vacuum conditions at 300°C.

[0025] After 100 thermal cycles at -196℃ to +300℃, the thermal conductivity decreases by ≤3%.

[0026] Density ≤ 1.9 g / cm³ 3 Total mass loss (TML) < 0.5% (300℃ / 1000h).

[0027] This invention also provides an application of the aforementioned composite material in a spacecraft heat sink. The heat sink is connected to the spacecraft structure by welding or adhesive bonding, with a joint surface thermal resistance ≤0.5 K·cm. 2 / W.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0029] (1) Breakthrough in synergistic effect of high temperature resistance and high thermal conductivity. Traditional polymer-based materials (such as ordinary polyimide) generally have a thermal conductivity of less than 50 W / m·K at 300℃ and are easy to decompose. However, this invention achieves a thermal conductivity of ≥140 W / m·K at 300℃ (nearly 3 times higher) through the synergistic design of silane-modified matrix (SAPI) + high thermal conductivity carbon fiber (MPCF) and a thermal decomposition temperature of 550℃, which meets the requirements of long-term high-temperature service.

[0030] (2) Significantly improved stability in space environment. Existing carbon fiber reinforced composite materials are prone to performance degradation of >20% after vacuum thermal cycling (-196℃ to +300℃) due to interfacial debonding. However, this invention, through PSZ coating and gradient interface design, enables the material to achieve a thermal conductivity degradation of <5% after 30 thermal cycles, a flexural strength retention rate of >90%, and a mass loss of <1% after atomic oxygen irradiation, which is far superior to traditional materials (>5%).

[0031] (3) Lightweight design and structural functionality are integrated. Compared to aluminum-based composite materials (density > 2.7 g / cm³),... 3 The density of this invention is ≤1.9 g / cm³. 3 It reduces weight by more than 30%, perfectly meeting the lightweight and efficient heat dissipation requirements of spacecraft. Attached Figure Description

[0032] Other features, objects, and advantages of the present invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0033] Figure 1 This is a schematic diagram of the ply structure of Embodiment 1 of the present invention;

[0034] Figure 2 This is a schematic diagram of the layup structure in Embodiment 4 of the present invention. Detailed Implementation

[0035] The present invention will be described in detail below with reference to embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the invention in any way. It should be noted that those skilled in the art can make several adjustments and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0036] (1) The high thermal conductivity fiber reinforcement and surface treatment of the present invention. Mesophase pitch-based carbon fiber (MPCF) is used as the reinforcement, with an axial thermal conductivity ≥600 W / m·K. A polysilazane (PSZ) coating is deposited on the surface to enhance interfacial bonding and achieve a modulus buffer transition between the resin and the fiber. The fiber-matrix bonding strength is increased by 40%, and high-temperature debonding is reduced. The PSZ coating has the effect of resisting space irradiation and shielding atomic oxygen and gamma rays. The mass loss of the composite material after irradiation is <1%, and the oxidation rate under vacuum at 300℃ is reduced to 20% of that of the uncoated fiber.

[0037] (2) Interface gradient design. A transition layer (polysilazane) is introduced at the fiber-matrix (resin) interface to adjust the coefficient of thermal expansion (CTE) and chemical bonding strength, thereby reducing the interfacial thermal resistance by 30% and ensuring efficient heat transfer at high temperatures.

[0038] (3) Fiber volume content design and control. By controlling the layup design and molding process, the overall composition of the composite material component is controlled, thereby improving the thermal conductivity of the composite material.

[0039] (4) The composite material obtained by this invention has an axial thermal conductivity ≥140W / m·K and a flexural strength retention rate ≥80% under vacuum conditions at 300℃; after 100 thermal cycles from -196℃ to +300℃, the thermal conductivity decreases by ≤5%; and the density is ≤1.9g / cm³. 3 Total mass loss (TML) < 0.5% (300℃ / 1000h).

[0040] Unless otherwise specified, percentage content and percentage concentration in this invention refer to mass percentage content and mass percentage concentration. Unless otherwise specified, all raw materials are commercially available.

[0041] Pitch-based carbon fiber (MPCF): Tianze TC-20 fiber, axial thermal conductivity ≥600W / m·K;

[0042] Silicon-containing aromatic yne-modified polyimide (SAPI) resin: East China University of Science and Technology PSI, the synthesis method refers to Example 1 of patent CN202111681806.8.

[0043] Example 1

[0044] This embodiment provides a high-temperature resistant and high-thermal-conductivity composite material, the preparation method of which is as follows:

[0045] (1) The pitch-based carbon fiber was vacuum treated at 400℃ to remove the surface protective layer. The treated carbon fiber was then immersed in a 3wt% polysilazane solution for 30 min and cured at 120℃ for 1 h to complete the surface treatment of the carbon fiber. A 40 g / m² polyimide modified with silane and arylene was prepared using a hot-melt film-forming machine. 2The adhesive film is divided into two parts: one part is composited with high thermal conductivity carbon fibers to prepare a hot-melt prepreg (fiber volume fraction 62±2%), and the other part remains in the form of the adhesive film. The designed layup method is unidirectional layup, with a total of 11 layers (e.g., ...). Figure 1 As shown), layers 1-3, 6, and 9-11 are hot-melt prepregs, and layers 4, 5, 7, and 8 are adhesive films, resulting in a preform (the thickness of the surface prepreg layer is 20%; the thickness of the prepreg in the core prepreg layer is 20%; the remaining 40% is the adhesive film in the core prepreg).

[0046] (2) After layup, the product is subjected to step-by-step heating and hot-pressing curing in the furnace according to the following process:

[0047] The temperature was raised to 80℃ for the first time and held for 1 hour; the temperature was raised to 150℃ for the second time and held for 1 hour; the temperature was raised to 220℃ for the third time and held for 3 hours; and the temperature was raised to 350℃ for the fourth time and held for 3 hours.

[0048] The pressure changes were as follows: the first temperature was raised to 80℃ and contact pressure was applied; the third temperature was raised to 220℃ and pressure was applied to 0.5MPa; after holding at this temperature for 3 hours, pressure was applied to 5MPa and held, finally yielding the high-temperature resistant and high-thermal-conductivity composite material.

[0049] Performance testing:

[0050] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 410℃, the thermal decomposition temperature in air atmosphere was 572℃, and the thermal conductivity was 177W / m·K.

[0051] The fiber volume content of the composite material was tested in the central region and the surface region. The results showed that the fiber volume content in the central region was 52% and the fiber volume content in the surface region was 70%.

[0052] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 81 MPa.

[0053] Example 2

[0054] This embodiment provides a high-temperature resistant and high-thermal-conductivity composite material, and the preparation method is as follows:

[0055] (1) The pitch-based carbon fiber was vacuum treated at 400℃ to remove the surface protective layer. The treated carbon fiber was then immersed in a 10wt% polysilazane solution for 30 min and cured at 120℃ for 1 h to complete the surface treatment of the carbon fiber. A 40 g / m² polyimide modified with silane and arylene was prepared using a hot-melt film-forming machine. 2The adhesive film is divided into two parts: one part is combined with high thermal conductivity carbon fiber to prepare a hot-melt prepreg (fiber volume fraction 62±2%), and the other part remains in the form of an adhesive film. The design of the layup is unidirectional layup, with a total of 11 layers. Among them, layers 1-3, 6, and 9-11 are hot-melt prepreg, and layers 4, 5, 7, and 8 are adhesive films, resulting in a preform (the thickness of the surface prepreg layer is 20%; the thickness of the prepreg in the core prepreg layer is 30%; the rest is the adhesive film in the core prepreg).

[0056] (2) After layup, the product is subjected to step-by-step heating and hot-pressing curing in the furnace according to the following process:

[0057] The temperature was raised to 80℃ for the first time and held for 1 hour; the temperature was raised to 150℃ for the second time and held for 1 hour; the temperature was raised to 220℃ for the third time and held for 3 hours; and the temperature was raised to 350℃ for the fourth time and held for 3 hours.

[0058] The pressure changes were as follows: the first temperature was raised to 80℃ and contact pressure was applied; the third temperature was raised to 220℃ and pressure was applied to 0.5MPa; after holding at this temperature for 3 hours, pressure was applied to 5MPa and held, finally yielding the high-temperature resistant and high-thermal-conductivity composite material.

[0059] Performance testing:

[0060] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 410℃, the thermal decomposition temperature in air atmosphere was 572℃, and the thermal conductivity was 171W / m·K.

[0061] The fiber volume content of the composite material was tested in the central region and the surface region. The results showed that the fiber volume content in the central region was 52% and the fiber volume content in the surface region was 70%.

[0062] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 89 MPa.

[0063] Example 3

[0064] This embodiment provides a high-temperature resistant and high-thermal-conductivity composite material, and the preparation method is as follows:

[0065] (1) The pitch-based carbon fiber was vacuum treated at 400℃ to remove the surface protective layer. The treated carbon fiber was then immersed in a 3wt% polysilazane solution for 30 min and cured at 120℃ for 1 h to complete the surface treatment of the carbon fiber. A 75 g / m² polyimide modified with silane and arylene was prepared using a hot-melt film-forming machine. 2The adhesive film is divided into two parts: one part is combined with high thermal conductivity carbon fiber to prepare a hot-melt prepreg (fiber volume fraction 62±2%), and the other part remains in the form of an adhesive film. The design of the layup is unidirectional layup, with a total of 11 layers. Among them, layers 1-3, 6, and 9-11 are hot-melt prepreg, and layers 4, 5, 7, and 8 are adhesive films, resulting in a preform (the thickness of the surface prepreg layer is 20%; the thickness of the prepreg in the core prepreg layer is 30%; the rest is the adhesive film in the core prepreg).

[0066] (2) After layup, the product is subjected to step-by-step heating and hot-pressing curing in the furnace according to the following process:

[0067] The temperature was raised to 80℃ for the first time and held for 1 hour; the temperature was raised to 150℃ for the second time and held for 1 hour; the temperature was raised to 220℃ for the third time and held for 3 hours; and the temperature was raised to 350℃ for the fourth time and held for 3 hours.

[0068] The pressure changes were as follows: the first temperature was raised to 80℃ and contact pressure was applied; the third temperature was raised to 220℃ and pressure was applied to 0.5MPa; after holding at this temperature for 3 hours, pressure was applied to 5MPa and held, finally yielding the high-temperature resistant and high-thermal-conductivity composite material.

[0069] Performance testing:

[0070] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 409℃, the thermal decomposition temperature in air atmosphere was 566℃, and the thermal conductivity was 151W / m·K.

[0071] The fiber volume content was tested in the central and surface regions of the composite material. The results showed that the fiber volume content in the central region was 50% and the fiber volume content in the surface region was 64%.

[0072] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 80 MPa.

[0073] Example 4

[0074] This embodiment provides a high-temperature resistant and high-thermal-conductivity composite material, and the preparation method is as follows:

[0075] (1) The pitch-based carbon fiber was vacuum treated at 400℃ to remove the surface protective layer. The treated carbon fiber was then immersed in a 3wt% polysilazane solution for 30 min and cured at 120℃ for 1 h to complete the surface treatment of the carbon fiber. A 40 g / m² polyimide modified with silane and arylene was prepared using a hot-melt film-forming machine. 2 The adhesive film is divided into two parts: one part is composited with high thermal conductivity carbon fiber to prepare a hot-melt prepreg, and the other part remains in the form of the adhesive film. The designed layup method is unidirectional layup, with a total of 17 layers (e.g., ...). Figure 2As shown), layers 1-5, 7, 9, 11 and 13-17 are hot-melt prepreg, and layers 6, 8, 10 and 12 are adhesive films, resulting in a preform (the thickness of the surface prepreg layer is 18%; the thickness of the prepreg in the core prepreg layer is 30%; the remainder is the adhesive film in the core prepreg).

[0076] (2) After layup, the product is subjected to step-by-step heating and hot-pressing curing in the furnace according to the following process:

[0077] The temperature was raised to 80℃ for the first time and held for 1 hour; the temperature was raised to 150℃ for the second time and held for 1 hour; the temperature was raised to 220℃ for the third time and held for 3 hours; and the temperature was raised to 350℃ for the fourth time and held for 3 hours.

[0078] The pressure changes were as follows: the first temperature was raised to 80℃ and contact pressure was applied; the third temperature was raised to 220℃ and pressure was applied to 0.5MPa; after holding at this temperature for 3 hours, pressure was applied to 5MPa and held, finally yielding the high-temperature resistant and high-thermal-conductivity composite material.

[0079] Performance testing:

[0080] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 410℃, the thermal decomposition temperature in air atmosphere was 572℃, and the thermal conductivity was 155W / m·K.

[0081] The fiber volume content of the composite material was tested in the central region and the surface region. The results showed that the fiber volume content in the central region was 58% and the fiber volume content in the surface region was 67%.

[0082] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 83 MPa.

[0083] Example 5

[0084] This embodiment provides a high-temperature resistant and high-thermal-conductivity composite material, and the preparation method is as follows:

[0085] (1) The pitch-based carbon fiber was vacuum treated at 400℃ to remove the surface protective layer. The treated carbon fiber was then immersed in a 3wt% polysilazane solution for 30 min and cured at 120℃ for 1 h to complete the surface treatment of the carbon fiber. A 40 g / m² polyimide modified with silane and arylene was prepared using a hot-melt film-forming machine. 2 The adhesive film is divided into two parts: one part is combined with high thermal conductivity carbon fiber to prepare a hot-melt prepreg, and the other part remains in the form of an adhesive film. The design of the layup is unidirectional layup, with a total of 11 layers. Among them, layers 1-3, 6, and 9-11 are hot-melt prepreg, and layers 4, 5, 7, and 8 are adhesive films, resulting in a preform (the thickness of the surface prepreg layer is 20%; the thickness of the prepreg in the core prepreg layer is 30%; the remainder is the adhesive film in the core prepreg).

[0086] (2) After layup, the product is subjected to step-by-step heating and hot-pressing curing in the furnace according to the following process:

[0087] The temperature was raised to 80℃ for the first time and held for 1 hour; the temperature was raised to 150℃ for the second time and held for 1.5 hours; the temperature was raised to 220℃ for the third time and held for 2 hours; and the temperature was raised to 350℃ for the fourth time and held for 2.5 hours.

[0088] The pressure changes were as follows: the first temperature was raised to 80℃ and contact pressure was applied; the third temperature was raised to 220℃ and pressure was applied to 0.5MPa; after holding at this temperature for 3 hours, pressure was applied to 5MPa and held, finally yielding the high-temperature resistant and high-thermal-conductivity composite material.

[0089] Performance testing:

[0090] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 404℃, the thermal decomposition temperature in air atmosphere was 565℃, and the thermal conductivity was 176W / m·K.

[0091] The fiber volume content of the composite material was tested in the central region and the surface region. The results showed that the fiber volume content in the central region was 52% and the fiber volume content in the surface region was 70%.

[0092] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 88 MPa.

[0093] Example 6

[0094] This embodiment provides a high-temperature resistant and high-thermal-conductivity composite material, and the preparation method is as follows:

[0095] (1) The pitch-based carbon fiber was vacuum treated at 400℃ to remove the surface protective layer. The treated carbon fiber was then immersed in a 5wt% polysilazane solution for 30 min and cured at 120℃ for 1 h to complete the surface treatment of the carbon fiber. A 50 g / m² polyimide modified with silane and acetylenes was prepared using a hot-melt film-forming machine. 2 The adhesive film is divided into two parts: one part is combined with high thermal conductivity carbon fiber to prepare a hot-melt prepreg, and the other part remains in the form of an adhesive film. The design of the layup is unidirectional layup, with a total of 11 layers. Among them, layers 1-3, 6, and 9-11 are hot-melt prepreg, and layers 4, 5, 7, and 8 are adhesive films, resulting in a preform (the thickness of the surface prepreg layer is 20%; the thickness of the prepreg in the core prepreg layer is 30%; the remainder is the adhesive film in the core prepreg).

[0096] (2) After layup, the product is subjected to step-by-step heating and hot-pressing curing in the furnace according to the following process:

[0097] The temperature was raised to 80℃ for the first time and held for 1 hour; the temperature was raised to 150℃ for the second time and held for 1 hour; the temperature was raised to 220℃ for the third time and held for 3 hours; and the temperature was raised to 350℃ for the fourth time and held for 4 hours.

[0098] The pressure changes were as follows: the first temperature was raised to 80℃ and contact pressure was applied; the third temperature was raised to 220℃ and pressure was applied to 1MPa; after holding at this temperature for 3 hours, pressure was applied to 5MPa and held; finally, the high-temperature resistant and high-thermal-conductivity composite material was obtained.

[0099] Performance testing:

[0100] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 411℃, the thermal decomposition temperature in air atmosphere was 572℃, and the thermal conductivity was 166W / m·K.

[0101] The fiber volume content was tested in the central and surface regions of the composite material. The results showed that the fiber volume content in the central region was 50% and the fiber volume content in the surface region was 66%.

[0102] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 89 MPa.

[0103] Example 7

[0104] This embodiment provides a high-temperature resistant and high-thermal-conductivity composite material, and the preparation method is as follows:

[0105] (1) The pitch-based carbon fiber was vacuum treated at 400℃ to remove the surface protective layer. The treated carbon fiber was then immersed in a 3wt% polysilazane solution for 30 min and cured at 120℃ for 1 h to complete the surface treatment of the carbon fiber. A 70 g / m² polyimide modified with silane and arylene was prepared using a hot-melt film-forming machine. 2 The adhesive film is divided into two parts: one part is combined with high thermal conductivity carbon fiber to prepare a hot-melt prepreg, and the other part remains in the form of an adhesive film. The design is a unidirectional layup with a total of 11 layers. Layers 1-3, 5-8, and 9-11 are hot-melt prepregs, and layers 4 and 7 are adhesive films, resulting in a preform (the thickness of the surface prepreg layer is 20%; the thickness of the prepreg in the core prepreg layer is 20%; the remainder is the adhesive film in the core prepreg).

[0106] (2) After layup, the product is subjected to step-by-step heating and hot-pressing curing in the furnace according to the following process:

[0107] The temperature was raised to 80℃ for the first time and held for 1 hour; the temperature was raised to 150℃ for the second time and held for 1 hour; the temperature was raised to 220℃ for the third time and held for 3 hours; and the temperature was raised to 350℃ for the fourth time and held for 3 hours.

[0108] The pressure changes were as follows: the first temperature was raised to 80℃ and contact pressure was applied; the third temperature was raised to 220℃ and pressure was applied to 0.5MPa; after holding at this temperature for 3 hours, pressure was applied to 5MPa and held, finally yielding the high-temperature resistant and high-thermal-conductivity composite material.

[0109] Performance testing:

[0110] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 411℃, the thermal decomposition temperature in air atmosphere was 569℃, and the thermal conductivity was 177W / m·K.

[0111] The fiber volume content of the composite material was tested in the central region and the surface region. The results showed that the fiber volume content in the central region was 59% and the fiber volume content in the surface region was 69%.

[0112] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 79 MPa.

[0113] Comparative Example 1

[0114] Variable adjustment: MPCF was not treated with PSZ coating, otherwise the same as in Example 1.

[0115] Performance testing:

[0116] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 405℃, the thermal decomposition temperature in air atmosphere was 555℃, and the thermal conductivity was 165W / m·K.

[0117] The fiber volume content was tested in the central and surface regions of the composite material. The results showed that the fiber volume content in the central region was 55% and the fiber volume content in the surface region was 70%.

[0118] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 53 MPa.

[0119] Comparative Example 2

[0120] Variable adjustment: The film layup design is cancelled (no 4, 5, 7, or 8 layers of film), and the rest is the same as in Example 1.

[0121] Performance testing:

[0122] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 378℃, the thermal decomposition temperature in air atmosphere was 566℃, and the thermal conductivity was 179W / m·K.

[0123] The fiber volume content of the composite material was tested in the central region and the surface region. The results showed that the fiber volume content in the central region was 63% and the fiber volume content in the surface region was 63%.

[0124] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 80 MPa.

[0125] Comparative Example 3

[0126] Variable adjustment: The silanine-containing polyimide (SAPI) resin was replaced with conventional polyimide without silanine, otherwise the same as in Example 1.

[0127] Performance testing:

[0128] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 360℃, the thermal decomposition temperature in air atmosphere was 552℃, and the thermal conductivity was 131W / m·K.

[0129] The fiber volume content of the composite material was tested in the central region and the surface region. The results showed that the fiber volume content in the central region was 30% and the fiber volume content in the surface region was 65%.

[0130] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 71 MPa.

[0131] Comparative Example 4

[0132] Variable adjustment: During the hot-press curing stage, the curing parameters are 80℃ / 2h + 350℃ / 6h. The pressurization process is to apply contact pressure at 80℃, then increase the temperature to 350℃ and pressurize to 5MPa, and maintain the pressure. The rest is the same as in Example 1.

[0133] Performance testing:

[0134] The temperature resistance and thermal conductivity of the composite material were tested. The results showed that the glass transition temperature of the composite material was 409℃, the thermal decomposition temperature in air atmosphere was 569℃, and the thermal conductivity was 127W / m·K.

[0135] The fiber volume content of the composite material was tested in the central region and the surface region. The results showed that the fiber volume content in the central region was 63% and the fiber volume content in the surface region was 63%.

[0136] The interlaminar shear strength of the composite material was tested according to JC / T 773, and the interlaminar shear strength was 54 MPa.

[0137] The specific embodiments of the present invention have been described above. It should be understood that the present invention is not limited to the specific embodiments described above, and those skilled in the art can make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a high-temperature resistant and high-thermal-conductivity composite material, characterized in that, Includes the following steps: S1. Impregnate pitch-based carbon fiber in a polysilazane solution, remove and cure to obtain surface-treated pitch-based carbon fiber; S2. A prepreg is prepared by hot-melt method, which involves combining surface-treated pitch-based carbon fibers with an adhesive film. The adhesive film is prepared by hot-melt method using silane-modified polyimide. S3. The prepreg and the polyimide film modified with silane are unidirectionally laid up, and the surface prepreg layer, the core prepreg layer and the surface prepreg layer are laid up in sequence to obtain the preform; the surface prepreg layer is obtained by directly laying up the prepreg, and the core prepreg layer is obtained by alternately laying up the film and the prepreg, and both sides of the obtained core prepreg layer are film. S4. The preform is subjected to stepped heating and hot pressing curing to obtain the high temperature resistant and high thermal conductivity composite material. In step S1, the polysilazane content in the polysilazane solution is 2-10 wt%. In step S4, during the stepped heating and hot-pressing curing process, the temperature changes are as follows: the first temperature is raised to 80-100℃ and held for 1-2 hours; the second temperature is raised to 130-150℃ and held for 1-2 hours; the third temperature is raised to 180-220℃ and held for 1-3 hours; and the fourth temperature is raised to 340-370℃ and held for 2-5 hours. The pressure changes are as follows: after the first temperature increase, contact pressure is applied and the temperature is held; after the third temperature increase, pressure is applied to 0.5-1MPa and the temperature is held; after holding the temperature, pressure is applied to 4-6MPa, and the fourth temperature increase begins.

2. The method for preparing the high thermal conductivity composite material according to claim 1, characterized in that, In step S1, the diameter of the pitch-based carbon fiber is 14±2μm; And / or, the axial thermal conductivity of pitch-based carbon fibers is ≥600 W / m·K.

3. The method for preparing the high thermal conductivity composite material according to claim 1, characterized in that, In step S1, the soaking time is 25-35 minutes; And / or, the curing temperature is 115-135℃, and the time is 0.5-2h.

4. The method for preparing the high thermal conductivity composite material according to claim 1, characterized in that, The surface-treated pitch-based carbon fiber obtained in step S1 is coated with polysilazane to form a polysilazane interface layer; the thickness of the polysilazane interface layer is 30-100 nm.

5. The method for preparing the high thermal conductivity composite material according to claim 1, characterized in that, In the prepreg obtained in step S2, the volume fraction of pitch-based carbon fiber is 50-70%.

6. The method for preparing the high thermal conductivity composite material according to claim 1, characterized in that, In step S3, the thickness of the surface prepreg layer is 5%-20% of the preform thickness; the thickness of the prepreg in the core prepreg layer is 10%-30% of the preform thickness; the remainder is the adhesive film in the core prepreg. And / or, the alternation of the ply is 1-5 times.

7. The method for preparing the high thermal conductivity composite material according to claim 1, characterized in that, In step S4, the fiber volume fraction in the obtained high temperature resistant and high thermal conductivity composite material is 64-80% in the surface region and 45-60% in the central region.

8. A high thermal conductivity composite material obtained by the preparation method according to claim 1, characterized in that, The composite material exhibits an axial thermal conductivity ≥140 W / m·K and a flexural strength retention rate ≥80% under vacuum conditions at 300℃. And / or, after 100 thermal cycles at -196℃ to +300℃, the thermal conductivity decreases by ≤3%; And / or, density ≤ 1.9 g / cm³ 3 Total mass loss <0.5%.

9. The application of a high thermal conductivity composite material obtained by the preparation method as described in claim 1 in a spacecraft heat sink.

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