High-temperature-resistant porcelainizable silicone resin composite material and preparation method thereof

Abstract

The application discloses a high-temperature-resistant and porcelainizable silicon resin composite material and a preparation method thereof, and belongs to the technical field of organic polymer materials. The silicon resin composite material is modified by polydopamine modified boron carbide and two kinds of low-melting-point glass powder, and the gradient synergy of the polydopamine modified boron carbide and the two kinds of low-melting-point glass powder can make the silicon resin composite material generate phase transition from a silicon dioxide phase to a B2SiO5 phase and then to a Mg2SiO4 phase in a high-temperature thermal aging process, and the B2SiO5 phase and the Mg2SiO4 phase can form a B2SiO5-Mg2SiO4 ceramic network, which, in cooperation with SiC, endows the composite material with excellent high-temperature mechanical properties. The silicon resin composite material provided by the application can generate phase transition at high temperature, the mechanical properties are significantly improved, good processing performance and mechanical strength are maintained, and the silicon resin composite material is suitable for high-performance structural parts and other composite material products in the field of aerospace.

Description

Technical Field

[0001] This invention belongs to the field of organic polymer materials technology, and particularly relates to a high-temperature resistant, ceramic-compatible silicone resin composite material and its preparation method. Background Technology

[0002] Silicone resin is the base resin for high-temperature resistant, ceramic-like silicone resin composites. There are many types, the most common being methylphenyl silicone resin, methyl silicone resin, and phenyl silicone resin. Methylphenyl silicone resin, due to the introduction of phenyl groups, has increased molecular chain rigidity and heat resistance, thus exhibiting good high-temperature resistance and mechanical properties. Under high-temperature environments, methylphenyl silicone resin maintains good structural stability, and its thermal decomposition temperature is relatively high, generally reaching 400-500℃. Simultaneously, it has good compatibility with fillers, uniformly dispersing them and improving the overall performance of the material. For example, in certain high-temperature components in the aerospace field, methylphenyl silicone resin is used as the matrix material, effectively withstanding high temperatures and mechanical loads. Methyl silicone resin is characterized by fast curing speed and high hardness. Its curing process is relatively simple, forming a hard protective film or product in a short time, and it is often used in applications requiring high curing speed and hardness, such as encapsulation materials for electronic devices. Phenyl silicone resin has excellent high-temperature resistance, with a thermal decomposition temperature exceeding 500℃, and also possesses good oxidation resistance. However, phenyl silicone resin is relatively brittle and prone to fracture when subjected to external impact. In applications requiring high-temperature oxidation resistance, such as lining materials for high-temperature furnaces, phenyl silicone resin can demonstrate its advantages.

[0003] Fillers play a crucial role in high-temperature resistant ceramicizable silicone resin composites, significantly improving material performance and meeting the needs of various applications. Ceramic powders are commonly used fillers, such as boron carbide (B4C), silicon carbide (SiC), silicon nitride (Si3N4), and alumina (Al2O3). Among them, boron carbide (B4C) is a ceramicizable filler known for its high hardness and lightweight properties. Its chemical and physical properties determine its unique position in numerous industrial applications. The high-temperature reactivity of boron carbide determines its application potential in extreme environments. Boron carbide has an extremely high melting point (approximately 2763℃), maintaining structural and property stability at high temperatures. Its excellent thermal stability at high temperatures makes it resistant to decomposition or phase transformation under high-temperature melting and mechanical stress. This characteristic makes it an indispensable material in aerospace and high-temperature industrial equipment. For example, Chinese patent CN117567155A uses at least one of polyethersulfone and polyacrylonitrile as polymer raw materials and adds boron carbide to prepare a boron carbide composite material with a low coefficient of thermal expansion and higher fracture energy, which can be applied to cutting tools, ballistic protection equipment, and high-temperature ceramic parts. Another example is Chinese patent CN116835987A, which uses carbon black powder and boron carbide to prepare a boron carbide-nano SiC ceramic composite material. This patent has a higher cost and a relatively complex processing technology. Although boron carbide begins to react with oxygen at temperatures above 400°C to generate boron oxide (B2O3) and carbon dioxide (CO2), and boron oxide can form a dense protective film on the material surface to further prevent oxygen penetration and thus slow down further oxidation of the material, at extremely high temperatures (above 1500°C), the oxide protective film may melt and be lost, leading to accelerated oxidation of boron carbide, ultimately resulting in a decrease in the high-temperature thermal aging resistance and insufficient mechanical strength of the silicone resin composite material. Summary of the Invention

[0004] To address the problems of cracking after high-temperature thermal aging, low mechanical strength, and complex preparation processes of current silicone resin composite materials, this invention proposes a high-temperature resistant, ceramic-compatible silicone resin composite material and its preparation method.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] This invention provides a high-temperature resistant, ceramic-compatible silicone resin composite material, comprising the following components by weight: 100 parts methylphenyl silicone resin, 15-20 parts modified boron carbide, 15-20 parts talc powder, 10-30 parts low-melting-point glass powder I, 10-30 parts low-melting-point glass powder II, 0.01-2.50 parts curing agent, and 0.1-5.0 parts release agent;

[0007] The modified boron carbide is polydopamine-modified boron carbide (PDA@B4C); the low-melting-point glass powder I and low-melting-point glass powder II have different melting points.

[0008] Technical Principle: This invention employs polydopamine-modified boron carbide and two types of low-melting-point glass powders to modify silicone resin composites. The gradient synergy of polydopamine-modified boron carbide and the two types of low-melting-point glass powders enables the silicone resin composite to undergo a phase transformation from silica phase to high-temperature resistant glass phase (B2SiO5 phase) and then to Mg2SiO4 phase during high-temperature thermal aging. Furthermore, the B2SiO5 phase and Mg2SiO4 phase can form a B2SiO5-Mg2SiO4 ceramic network, which, together with SiC, endows the composite with excellent high-temperature mechanical properties. Boron carbide, talc, and two types of low-melting-point glass powders with different melting points are used as ceramic fillers to achieve a segmented melting effect, improve interfacial adhesion, accelerate the ceramicization of the material, and enhance the mechanical properties of the silicone resin composite after high-temperature thermal aging. By introducing polydopamine to modify the surface of boron carbide, the interface between boron carbide and the silicone resin matrix is ​​improved, while the oxidation damage of boron carbide is reduced, effectively preventing cracking of the silicone resin composite.

[0009] By surface-modifying boron carbide with polydopamine, polydopamine-modified boron carbide PDA@B4C was obtained. The modified PDA@B4C can form a reinforcing interface layer with the resin matrix, generating an interface effect, thereby significantly improving the high temperature resistance and mechanical properties of silicone resin composites. Furthermore, the polydopamine layer can protect B4C from oxidation damage within a certain temperature range, preventing the formation of excessive B2O3 due to the oxidation reaction of B4C, which could lead to cracking of the silicone resin composite.

[0010] The low-melting-point glass powder I and low-melting-point glass powder II used can improve the interfacial adhesion between the filler and the matrix, and enhance the mechanical properties of silicone resin composites after high-temperature thermal aging. At the same time, the fluxing agent, such as low-melting-point glass powder, can generate a large amount of liquid phase after melting at high temperature, thereby forming a good ceramic structure, improving the thermal stability and mechanical properties of silicone resin composites. Low-melting-point glass powder can also control the ceramicization temperature of ceramicizable silicone resin composites and improve the residual rate of silicone resin composites after ablation.

[0011] The talc powder used decomposes into magnesium silicate and a large amount of SiO2 at a high temperature of 800℃. SiO2 can undergo a eutectic melting reaction with B2O3 to generate a high-temperature resistant borosilicate glass component, thereby improving the mechanical properties of the silicone resin composite material after high-temperature thermal aging.

[0012] Furthermore, the preparation method of the polydopamine-modified boron carbide includes the following steps: adding dopamine to a Tris-HCl solution to carry out a polymerization reaction to obtain a polydopamine solution; adding boron carbide powder to the polydopamine solution, and then stirring, filtering, washing and drying to obtain the polydopamine-modified boron carbide.

[0013] Furthermore, the boron carbide has a particle size of 1-10 micrometers; the mass ratio of dopamine to boron carbide is 1:60.

[0014] Furthermore, the particle size of the talc powder is 1000~1250 mesh.

[0015] Furthermore, the melting point of the low-melting-point glass powder I is 300~400℃; the melting point of the low-melting-point glass powder II is 400~780℃.

[0016] Furthermore, the curing agent is selected from at least one of N,N-dimethylbenzylamine, benzoic anhydride, benzoic acid, and basic lead carbonate.

[0017] Furthermore, the release agent is selected from calcium stearate, magnesium stearate, or zinc stearate.

[0018] This invention also provides a method for preparing a high-temperature resistant, ceramic-compatible silicone resin composite material as described above, comprising the following steps:

[0019] (1) Modified boron carbide, talc powder, low melting point glass powder I and low melting point glass powder II are mixed evenly to obtain a mixed filler; methyl phenyl silicone resin is preheated to a molten state to obtain molten methyl phenyl silicone resin;

[0020] (2) The mixed filler is added to the molten methylphenyl silicone resin in batches for the first physical blending, and then a curing agent and a release agent are added for the second physical blending. After the blending is completed, the mixture is cooled, crushed and molded to obtain the high-temperature resistant and ceramic-compatible silicone resin composite material.

[0021] Further, in step (1), the preheating temperature is 110~120℃; and / or,

[0022] In step (2), the first physical blending time is 20-30 minutes and the rotation speed is 50-200 rpm; the second physical blending time is 5-15 minutes and the rotation speed is 50-200 rpm.

[0023] Further, in step (2), the molding process is as follows: first, hot pressing at 180°C and 15MPa for 10~30 minutes, and then curing at 200°C for 4 hours.

[0024] Compared with the prior art, the present invention has the following advantages and technical effects:

[0025] The high-temperature resistant, porcelain-like silicone resin composite material of this invention comprises methylphenyl silicone resin, modified boron carbide, talc, low-melting-point glass powder, a release agent, and a curing agent. This invention uses polydopamine to surface-modify boron carbide, and combines it with talc as a porcelain-forming filler. Low-melting-point glass powder is used as a flux and reinforcing filler. Through a mixing process, the composite material is uniformly compounded with the curing agent and release agent, ultimately yielding a silicone resin composite material with excellent high-temperature resistance. The silicone resin composite material provided by this invention undergoes a phase transformation at high temperatures, significantly improving its mechanical properties while maintaining good processability and mechanical strength. It is suitable for high-performance structural components and other composite material products in the aerospace field.

[0026] The high-temperature resistant, ceramic-like silicone resin composite material provided by this invention exhibits excellent mechanical properties after high-temperature thermal aging, with a significant improvement in flexural strength. It does not crack when heated to below 600°C. After thermal aging at 800°C for 0.5 hours, the flexural strength reaches 61.9 MPa, which is 38% higher than that of the untreated silicone resin composite material. After thermal aging at 800°C for 1 hour, the flexural strength of the high-temperature resistant, ceramic-like silicone resin composite material reaches 93.5 MPa, which is 108% higher than that of the untreated silicone resin composite material. Attached Figure Description

[0027] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0028] Figure 1 A schematic diagram of the in-situ self-polymerization process of dopamine;

[0029] Figure 2 The infrared spectra of boron carbide before and after modification in step (1) of Example 1 are shown.

[0030] Figure 3 The macroscopic morphology of the silicone resin composite materials prepared in Example 1 and Comparative Example 4 after static ablation at 400°C for 0.5 h and 1 h are shown. Y-6 is Comparative Example 4, Y-8 is Example 1, and so on.

[0031] Figure 4 The macroscopic morphology of the silicone resin composite materials prepared in Example 1 and Comparative Example 4 after static ablation at 600°C for 0.5 h and 1 h.

[0032] Figure 5 The macroscopic morphology of the silicone resin composite materials prepared in Example 1 and Comparative Example 4 after static ablation at 800°C for 0.5 h and 1 h.

[0033] Figure 6 The XRD pattern is shown for the high-temperature pyrolysis products of the high-temperature resistant and ceramic-compatible silicone resin composite material prepared in Example 1. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0035] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] This invention provides a high-temperature resistant, ceramic-compatible silicone resin composite material, comprising the following components by weight: 100 parts methylphenyl silicone resin, 15-20 parts modified boron carbide, 15-20 parts talc, 10-30 parts low-melting-point glass powder I, 10-30 parts low-melting-point glass powder II, 0.01-2.50 parts curing agent, and 0.1-5.0 parts release agent.

[0037] In a preferred embodiment, the modified boron carbide is polydopamine-modified boron carbide. Polydopamine (PDA) is a polymer obtained through dopamine polymerization (see schematic diagram of the in-situ self-polymerization process of dopamine). Figure 1 PDA can be synthesized under mild aqueous conditions simulating a marine environment. Due to the presence of multiple functional groups, PDA exhibits a strong affinity for various surfaces, and these functional groups can be attached to organic and inorganic materials. This invention utilizes polydopamine to surface-modify boron carbide. The resulting PDA@B4C can form a reinforcing interface layer with the resin matrix, generating an interfacial effect. This significantly improves the high-temperature resistance and mechanical properties of silicone resin composites. Furthermore, the polydopamine layer can protect B4C from oxidative damage within a certain temperature range, preventing the excessive production of B2O3 due to B4C oxidation, which could lead to cracking in the silicone resin composite.

[0038] In a preferred embodiment, the preparation method of the polydopamine-modified boron carbide includes the following steps: adding dopamine to a Tris-HCl solution to carry out a polymerization reaction to obtain a polydopamine solution; adding boron carbide powder to the polydopamine solution, and then stirring, filtering, washing and drying to obtain the polydopamine-modified boron carbide.

[0039] In a preferred embodiment, the pH of the Tris-HCl solution is 8.5; the concentration of the dopamine solution is 4 g / L. During the addition of dopamine to the Tris-HCl solution, an in-situ self-polymerization reaction of dopamine occurs, thereby obtaining a polydopamine solution.

[0040] In a preferred embodiment, the boron carbide has a particle size of 1-10 micrometers; the mass ratio of dopamine to boron carbide is 1:60; the stirring time is 24 hours, during which polydopamine modifies the surface of boron carbide.

[0041] In a preferred embodiment, the talc powder has a particle size of 1000-1250 mesh. At 800°C, the talc powder decomposes into magnesium silicate and a large amount of SiO2. SiO2 can undergo a eutectic melting reaction with B2O3 to generate a high-temperature resistant borosilicate glass component, thereby improving the mechanical properties of the silicone resin composite material after high-temperature thermal aging.

[0042] In a preferred embodiment, the low-melting-point glass powder I and low-melting-point glass powder II have different melting points. By employing low-melting-point glass powder I and low-melting-point glass powder II with different melting points, this invention can improve the interfacial adhesion between the filler and the matrix, thereby enhancing the mechanical properties of the silicone resin composite material after high-temperature thermal aging. Simultaneously, this type of flux, low-melting-point glass powder, can generate a large amount of liquid phase after melting at high temperatures, thus forming a good ceramic structure, improving the thermal stability and mechanical properties of the silicone resin composite material. Furthermore, low-melting-point glass powder can also control the ceramization temperature of the ceramicizable silicone resin composite material, increasing the residual rate of the silicone resin composite material after ablation.

[0043] In a preferred embodiment, the melting point of the low-melting-point glass powder I is 300~400℃, more preferably 300~350℃; and the melting point of the low-melting-point glass powder II is 400~780℃, more preferably 550~780℃.

[0044] In a preferred embodiment, the curing agent is selected from at least one of N,N-dimethylbenzylamine, benzoic anhydride, benzoic acid, and basic lead carbonate.

[0045] In a preferred embodiment, the release agent is selected from calcium stearate, magnesium stearate, or zinc stearate.

[0046] This invention also provides a method for preparing a high-temperature resistant, ceramic-compatible silicone resin composite material as described above, comprising the following steps:

[0047] (1) Modified boron carbide, talc powder, low melting point glass powder I and low melting point glass powder II are mixed evenly to obtain a mixed filler; methyl phenyl silicone resin is preheated to a molten state to obtain molten methyl phenyl silicone resin;

[0048] (2) The mixed filler is added to the molten methylphenyl silicone resin in batches for the first physical blending, and then a curing agent and a release agent are added for the second physical blending. After the blending is completed, the mixture is cooled, crushed and molded to obtain the high-temperature resistant and ceramic-compatible silicone resin composite material.

[0049] In a preferred embodiment, in step (1), the preheating temperature is 110~120℃.

[0050] In a preferred embodiment, in step (2), the batch addition is performed 3 to 6 times.

[0051] In a preferred embodiment, in step (2), the first physical blending time is 20-30 minutes and the rotation speed is 50-200 rpm; the first physical blending time is 5-15 minutes and the rotation speed is 50-200 rpm.

[0052] In a preferred embodiment, in step (2), pigments may also be added as needed, along with the curing agent and release agent.

[0053] In a preferred embodiment, in step (2), the molding process is as follows: first, hot pressing at 180°C and 15MPa for 10~30 minutes, and then curing at 200°C for 4 hours.

[0054] In this embodiment of the invention, room temperature refers to "25±2℃".

[0055] Unless otherwise specified, all raw materials used in the embodiments of this invention were purchased through commercial channels.

[0056] In the following examples and comparative examples, low-melting-point glass powder I and low-melting-point glass powder II were purchased from Anmi Micro-Nano New Materials Co., Ltd.

[0057] Example 1

[0058] A method for preparing a high-temperature resistant, ceramic-compatible silicone resin composite material, comprising the following steps:

[0059] (1) Prepare 1L of Tris-HCl buffer solution with pH 8.5, add 4g of dopamine to obtain a dopamine solution with a concentration of 4g / L; add 240g of boron carbide with a particle size of 1~10 micrometers to the obtained dopamine solution, stir at room temperature for 24h, and then filter, wash and dry to obtain PDA@B4C;

[0060] (2) Mix 15 parts of PDA@B4C prepared in step (1), 20 parts of talc powder with a particle size of 1000~1250 mesh, 20 parts of low melting point glass powder I with a melting point of 350℃ and 20 parts of low melting point glass powder II with a melting point of 550℃ evenly to obtain a mixed filler; preheat 100 parts of methylphenyl silicone resin to a molten state in a mixer at a preheating temperature of 110℃ to obtain molten methylphenyl silicone resin;

[0061] (3) The mixed filler obtained in step (2) is added to the molten methylphenyl silicone resin in 5 portions. The speed of the internal mixer is set to 200 rpm and the mixing is carried out for 25 minutes. Then, 1.5 parts of basic lead carbonate and 1.2 parts of calcium stearate are added and the mixing is continued at 200 rpm for 15 minutes. The product after mixing is taken out from the internal mixer, cooled, and pulverized to obtain organosilicon resin composite powder.

[0062] (4) The silicone resin composite material powder obtained in step (3) is molded. The molding process is as follows: hot pressing at 180℃ and 15MPa for 10 minutes, and then curing at 200℃ for 4 hours to obtain a sample of 80mm×10mm×4mm, which is a high-temperature resistant and ceramicizable silicone resin composite material.

[0063] Figure 2 The infrared spectra of boron carbide before and after modification in step (1) of Example 1 are shown. Figure 2 The successful modification of B4C surface by PDA was confirmed.

[0064] Example 2

[0065] A method for preparing a high-temperature resistant, ceramic-compatible silicone resin composite material, comprising the following steps:

[0066] (1) Prepare 1L of Tris-HCl buffer solution with pH 8.5, add 4g of dopamine to obtain a dopamine solution with a concentration of 4g / L; add 240g of boron carbide with a particle size of 1~10 micrometers to the obtained dopamine solution, stir at room temperature for 24h, and then filter, wash and dry to obtain PDA@B4C;

[0067] (2) Mix 20 parts of PDA@B4C prepared in step (1), 15 parts of talc powder with a particle size of 1000~1250 mesh, 20 parts of low melting point glass powder I with a melting point of 350℃ and 20 parts of low melting point glass powder II with a melting point of 550℃ evenly to obtain a mixed filler; preheat 100 parts of methylphenyl silicone resin to a molten state in a mixer at a preheating temperature of 120℃ to obtain molten methylphenyl silicone resin;

[0068] (3) The mixed filler obtained in step (2) is added to the molten methylphenyl silicone resin in three parts. The speed of the internal mixer is set to 200 rpm and the mixture is mixed for 30 minutes. Then, 1.0 part of N,N-dimethylbenzylamine and 1.0 part of magnesium stearate are added and the mixture is mixed for another 15 minutes at 200 rpm. The mixed product is taken out of the internal mixer, cooled, and pulverized to obtain organosilicon resin composite powder.

[0069] (4) The silicone resin composite material powder obtained in step (3) is molded. The molding process is as follows: hot pressing at 180℃ and 15MPa for 10 minutes, and then curing at 200℃ for 4 hours to obtain a sample of 80mm×10mm×4mm, which is a high-temperature resistant and ceramicizable silicone resin composite material.

[0070] Example 3

[0071] A method for preparing a high-temperature resistant, ceramic-compatible silicone resin composite material, comprising the following steps:

[0072] (1) Prepare 1L of Tris-HCl buffer solution with pH 8.5, add 4g of dopamine to obtain a dopamine solution with a concentration of 4g / L; add 240g of boron carbide with a particle size of 1~10 micrometers to the obtained dopamine solution, stir at room temperature for 24h, and then filter, wash and dry to obtain PDA@B4C;

[0073] (2) Mix 15 parts of PDA@B4C prepared in step (1), 18 parts of talc powder with a particle size of 1000~1250 mesh, 15 parts of low melting point glass powder I with a melting point of 350℃ and 25 parts of low melting point glass powder II with a melting point of 550℃ evenly to obtain a mixed filler; preheat 100 parts of methylphenyl silicone resin to a molten state in a mixer at a preheating temperature of 110℃ to obtain molten methylphenyl silicone resin;

[0074] (3) The mixed filler obtained in step (2) is added to the molten methylphenyl silicone resin in three parts. The speed of the internal mixer is set to 200 rpm and the mixing is carried out for 20 minutes. Then, 2.5 parts of benzoic acid and 5.0 parts of calcium stearate are added and the mixing is continued at 200 rpm for 15 minutes. The product after mixing is taken out from the internal mixer, cooled, and pulverized to obtain organosilicon resin composite powder.

[0075] (4) The silicone resin composite material powder obtained in step (3) is molded. The molding process is as follows: hot pressing at 180℃ and 15MPa for 10 minutes, and then curing at 200℃ for 4 hours to obtain a sample of 80mm×10mm×4mm, which is a high-temperature resistant and ceramicizable silicone resin composite material.

[0076] Example 4

[0077] A method for preparing a high-temperature resistant, ceramic-compatible silicone resin composite material, comprising the following steps:

[0078] (1) Prepare 1L of Tris-HCl buffer solution with pH 8.5, add 4g of dopamine to obtain a dopamine solution with a concentration of 4g / L; add 240g of boron carbide with a particle size of 1~10 micrometers to the obtained dopamine solution, stir at room temperature for 24h, and then filter, wash and dry to obtain PDA@B4C;

[0079] (2) Mix 20 parts of PDA@B4C prepared in step (1), 20 parts of talc powder with a particle size of 1000~1250 mesh, 25 parts of low melting point glass powder I with a melting point of 350℃ and 10 parts of low melting point glass powder II with a melting point of 550℃ evenly to obtain a mixed filler; preheat 100 parts of methylphenyl silicone resin to a molten state in a mixer at a preheating temperature of 110℃ to obtain molten methylphenyl silicone resin;

[0080] (3) The mixed filler obtained in step (2) is added to the molten methylphenyl silicone resin in 5 portions. The speed of the internal mixer is set to 200 rpm and the mixing is carried out for 30 minutes. Then, 1.0 part of benzoic anhydride and 1.0 part of zinc stearate are added and the mixing is continued at 200 rpm for 15 minutes. The product after mixing is taken out from the internal mixer, cooled, and pulverized to obtain organosilicon resin composite material powder.

[0081] (4) The silicone resin composite material powder obtained in step (3) is molded. The molding process is as follows: hot pressing at 180℃ and 15MPa for 10 minutes, and then curing at 200℃ for 4 hours to obtain a sample of 80mm×10mm×4mm, which is a high-temperature resistant and ceramicizable silicone resin composite material.

[0082] Example 5

[0083] A method for preparing a high-temperature resistant, ceramic-compatible silicone resin composite material, comprising the following steps:

[0084] (1) Prepare 1L of Tris-HCl buffer solution with pH 8.5, add 4g of dopamine to obtain a dopamine solution with a concentration of 4g / L; add 240g of boron carbide with a particle size of 1~10 micrometers to the obtained dopamine solution, stir at room temperature for 24h, and then filter, wash and dry to obtain PDA@B4C;

[0085] (2) Mix 15 parts of PDA@B4C prepared in step (1), 20 parts of talc powder with a particle size of 1000~1250 mesh, 20 parts of low melting point glass powder I with a melting point of 350℃ and 20 parts of low melting point glass powder II with a melting point of 550℃ evenly to obtain a mixed filler; preheat 100 parts of methylphenyl silicone resin to a molten state in a mixer at a preheating temperature of 120℃ to obtain molten methylphenyl silicone resin;

[0086] (3) The mixed filler obtained in step (2) is added to the molten methylphenyl silicone resin in 6 portions. The speed of the internal mixer is set to 200 rpm and the mixing is carried out for 30 minutes. Then, 2.0 parts of basic lead carbonate and 3.0 parts of zinc stearate are added and the mixing is continued at 200 rpm for 15 minutes. The product after mixing is taken out from the internal mixer, cooled, and pulverized to obtain organosilicon resin composite material powder.

[0087] (4) The silicone resin composite material powder obtained in step (3) is molded. The molding process is as follows: hot pressing at 180℃ and 15MPa for 10 minutes, and then curing at 200℃ for 4 hours to obtain a sample of 80mm×10mm×4mm, which is a high-temperature resistant and ceramicizable silicone resin composite material.

[0088] Comparative Example 1

[0089] A method for preparing a silicone resin composite material, comprising the following steps:

[0090] (1) 100 parts of methylphenyl silicone resin were preheated to a molten state in a mixer at a preheating temperature of 120°C to obtain molten methylphenyl silicone resin.

[0091] (2) Add 100 parts of 3000 mesh quartz powder in 5 portions to the molten methyl phenyl silicone resin obtained in step (1). Set the internal mixer roller speed to 200 rpm and mix for 30 minutes. Then add 1.5 parts of basic lead carbonate and 1.2 parts of calcium stearate and continue mixing at 200 rpm for 15 minutes. Take the mixed product out of the internal mixer, cool it, and pulverize it to obtain organosilicon resin composite powder.

[0092] (3) The silicone resin composite material powder obtained in step (2) is molded. The molding process is as follows: hot pressing at 180℃ and 15MPa for 10 minutes, and then curing at 200℃ for 4 hours to obtain a sample of 80mm×10mm×4mm, which is the silicone resin composite material.

[0093] Comparative Example 2

[0094] A method for preparing a silicone resin composite material, comprising the following steps:

[0095] (1) Mix 15 parts of boron carbide with a particle size of 1-10 micrometers, 20 parts of talc powder with a particle size of 1000-1250 mesh and 40 parts of low melting point glass powder I with a melting point of 350℃ evenly to obtain a mixed filler; preheat 100 parts of methylphenyl silicone resin to a molten state in a mixer at a preheating temperature of 120℃ to obtain molten methylphenyl silicone resin.

[0096] (2) The mixed filler obtained in step (1) is added to the molten methylphenyl silicone resin in 5 portions. The speed of the internal mixer is set to 200 rpm and the mixing is carried out for 30 minutes. Then, 1.5 parts of basic lead carbonate and 1.2 parts of calcium stearate are added and the mixing is continued at 200 rpm for 15 minutes. The product after mixing is taken out from the internal mixer, cooled, and pulverized to obtain organosilicon resin composite powder.

[0097] (3) The silicone resin composite material powder obtained in step (2) is molded. The molding process is as follows: hot pressing at 180℃ and 15MPa for 10 minutes, and then curing at 200℃ for 4 hours to obtain a sample of 80mm×10mm×4mm, which is the silicone resin composite material.

[0098] Comparative Example 3

[0099] A method for preparing a silicone resin composite material, comprising the following steps:

[0100] (1) Mix 15 parts of boron carbide with a particle size of 1-10 micrometers, 20 parts of talc powder with a particle size of 1000-1250 mesh, and 40 parts of low melting point glass powder II with a melting point of 550℃ evenly to obtain a mixed filler; preheat 100 parts of methylphenyl silicone resin to a molten state in a mixer at a preheating temperature of 120℃ to obtain molten methylphenyl silicone resin.

[0101] Steps (2) to (3) are the same as in Comparative Example 2.

[0102] Comparative Example 4

[0103] A method for preparing a silicone resin composite material, comprising the following steps:

[0104] (1) Mix 15 parts of boron carbide with a particle size of 1-10 micrometers, 20 parts of talc powder with a particle size of 1000-1250 mesh, 20 parts of low melting point glass powder I with a melting point of 350℃ and 20 parts of low melting point glass powder II with a melting point of 550℃ evenly to obtain a mixed filler; preheat 100 parts of methylphenyl silicone resin to a molten state in a mixer at a preheating temperature of 110℃ to obtain molten methylphenyl silicone resin.

[0105] Steps (2) to (3) are the same as in Example 1.

[0106] The flexural strength of the silicone resin composites prepared in Examples 1-5 and Comparative Examples 1-4 after different heat aging was tested according to the national standard GB / T9341-2008, and the test data are shown in Table 1; the impact strength of the silicone resin composites prepared in Examples 1-5 and Comparative Examples 1-4 after different heat aging was tested according to the national standard GB / T 229-2020, and the test data are shown in Table 2.

[0107] Table 1. Flexural strength (MPa) of silicone resin composites prepared in Examples 1-5 and Comparative Examples 1-4 after different thermal aging.

[0108]

[0109] Table 2 Impact strength (KJ / m) of silicone resin composite materials prepared in Examples 1-5 and Comparative Examples 1-4 after different heat aging. 2 )

[0110]

[0111] Note: In Tables 1 and 2, "-" indicates that the sample is damaged and data cannot be obtained.

[0112] As shown in Tables 1 and 2, the high-temperature resistant, ceramic-like silicone resin composite material prepared in Example 1 exhibits a flexural strength of 93.49 MPa after heat aging at 800℃ for 1 h (a 108% increase compared to the untreated group), demonstrating the antioxidant protective effect of polydopamine on boron carbide. The high-temperature resistance of the silicone resin composite materials prepared in Comparative Examples 1-3 is lower than that of Comparative Example 4 and Examples 1-5 due to the lack of segmented melting effect. The high-temperature resistant, ceramic-like silicone resin composite material prepared in Example 1 achieves an impact strength of 3.97 KJ / m² after heat aging at 800℃ for 1 h (far exceeding other groups), confirming that polydopamine modification improves interfacial bonding. Furthermore, the combination of dual low-melting-point glass powder + talc powder (Comparative Example 4 and Examples 1-5) is significantly superior to the single-component system (Comparative Examples 1-3).

[0113] To investigate the ablation resistance and dimensional stability at high temperatures of the silicone resin composite material prepared with polydopamine-modified boron carbide (Example 1) and the silicone resin composite material prepared with unmodified boron carbide (Comparative Example 4), static thermal radiation was used to test Comparative Example 4 (Y-6) and Example 1 (Y-8). The results are shown in [Figure 1]. Figures 3-5 .

[0114] Figure 3 The macroscopic morphologies of the silicone resin composite materials prepared in Example 1 and Comparative Example 4 after static ablation at 400°C for 0.5 h and 1 h are shown. Y-6 represents Comparative Example 4, and Y-8 represents Example 1, and so on. Figure 3It can be seen that all composite material samples basically maintained their original morphology and size, but most samples had cracks on their surface. This is mainly attributed to the cracking reaction of the silicone resin matrix in the samples at high temperature, which generates small molecule gases, increasing the internal pressure of the material. In addition, the material is subjected to thermal stress at high temperature, resulting in cracks on the material surface. When the temperature is 400℃ and the holding time is 0.5h, there are no obvious cracks on the front of the Comparative Example 4 sample, but short cracks appear on the side, while no cracks appear on the front or side of the Example 1 sample. After increasing the holding time to 1h (400℃, 1h), long cracks appear on the front and side of the Comparative Example 4 sample, while there are still no obvious cracks on the front and side of the Example 1 sample. This indicates that the ablation resistance of Example 1 is better than that of Comparative Example 4. This is because PDA@B4C has better oxidation resistance than B4C at high temperature.

[0115] Figure 4 The macroscopic morphology of the silicone resin composite materials prepared in Example 1 and Comparative Example 4 after static ablation at 600°C for 0.5 h and 1 h are shown. Figure 4 It can be seen that when the temperature is 600℃ and the holding time is 0.5h, long cracks appear on both the front and side of the Comparative Example 4 sample, while short cracks appear only on the side of the Example 1 sample. That is, the high temperature of 600℃ still causes less damage to Example 1 than to Comparative Example 4. However, after increasing the holding time to 1h (600℃, 1h), the cracks in the Comparative Example 4 sample healed. This should be attributed to the oxidation reaction of B4C at high temperature, and the generated B2O3 reacts with the silicon oxide in the composite material to form a eutectic melt, which forms a highly viscous melt. These melts flow and migrate at high temperature, filling the cracks.

[0116] Figure 5 The macroscopic morphology of the silicone resin composite materials prepared in Example 1 and Comparative Example 4 after static ablation at 800°C for 0.5 h and 1 h are shown. Figure 5 It can be seen that when the temperature is 800℃ and the holding time is 0.5h, all samples turn black, the white B2O3 on the surface disappears, and cracks reappear on the sides of the samples of Comparative Example 4 and Example 1. This is mainly attributed to the cracking reaction of the silicone resin matrix of the samples at high temperature, the carbonization of organic components, and the insufficient time of the eutectic melt to fully regulate the internal stress at high temperature, thus causing cracks on the material surface. After increasing the holding time to 1h (800℃, 1h), long cracks reappear on the front of the sample of Comparative Example 4, and the cracks on the side have healed. However, no cracks are generated on the front of the sample of Example 1, only short cracks on the side. This is because when the temperature rises to 800℃, the flow and filling of the B2O3 and SiO2 eutectic melt generated by the oxidation of B4C at 600℃ in the composite material achieves partial healing of the cracks.

[0117] Phase analysis of the pyrolysis products of the high-temperature resistant, ceramic-like silicone resin composite material prepared in Example 1 after static ablation at different temperatures was performed by X-ray diffraction (XRD). The results are shown in the figure. Figure 6 .

[0118] Figure 6 The image shows the XRD pattern of the high-temperature pyrolysis products of the high-temperature resistant, ceramic-compatible silicone resin composite material prepared in Example 1. From... Figure 6 It can be seen that at 400℃, the main crystalline phase is silicon dioxide generated by the pyrolysis reaction of B4C and the silicone resin side chain. When the temperature rises to 600℃, the PDA coating fails, the oxidation reaction of B4C is no longer restricted, and a large amount of B2O3 begins to be generated. The XRD pattern shows that some B4C diffraction peaks have disappeared, which is evidence of the large-scale oxidation reaction of B4C. At the same time, a weak diffraction peak is also detected in the XRD pattern. This diffraction peak belongs to B2SiO5 (B2O3-SiO2 in the figure), indicating that B2O3 and SiO2 have undergone a eutectic reaction to generate a high-temperature resistant glass phase. When the temperature rises to 800℃, the oxidation of B4C intensifies, and its main peak intensity decreases significantly, while the diffraction peak intensity of B2SiO5 reaches its peak value and reacts with MgO in the low-melting-point glass powder to generate Mg2SiO4, forming a continuous ceramic network. Furthermore, XRD patterns confirmed the interfacial reaction between B4C and free silicon generated from the cracking of silicone resin (B4C+3Si→SiC+3B). This phase transformation is directly related to the improvement of material properties: the synergistic effect of the B2SiO5-Mg2SiO4 ceramic network and SiC endows the composite material with excellent high-temperature mechanical properties (bending strength of 93.5MPa at 800℃), while the interface optimization effect of PDA modification further enhances the oxidation resistance and structural stability of the material at extreme temperatures.

[0119] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-temperature resistant, ceramic-compatible silicone resin composite material, characterized in that, The product contains the following components by weight: 100 parts methyl phenyl silicone resin, 15-20 parts modified boron carbide, 15-20 parts talc powder, 10-30 parts low melting point glass powder I, 10-30 parts low melting point glass powder II, 0.01-2.50 parts curing agent, and 0.1-5.0 parts release agent. The modified boron carbide is polydopamine-modified boron carbide; The low-melting-point glass powder I and the low-melting-point glass powder II have different melting points; The preparation method of the polydopamine-modified boron carbide includes the following steps: adding dopamine to Tris-HCl solution to carry out a polymerization reaction to obtain a polydopamine solution; adding boron carbide powder to the polydopamine solution, and then stirring, filtering, washing and drying to obtain the polydopamine-modified boron carbide. The boron carbide has a particle size of 1-10 micrometers; the mass ratio of dopamine to boron carbide is 1:60; The melting point of the low-melting-point glass powder I is 300~400℃; the melting point of the low-melting-point glass powder II is 400~780℃.

2. The high-temperature resistant, ceramic-compatible silicone resin composite material according to claim 1, characterized in that, The talc powder has a particle size of 1000~1250 mesh.

3. The high-temperature resistant, ceramic-compatible silicone resin composite material according to claim 1, characterized in that, The curing agent is selected from at least one of N,N-dimethylbenzylamine, benzoic anhydride, benzoic acid, and basic lead carbonate.

4. The high-temperature resistant, ceramic-compatible silicone resin composite material according to claim 1, characterized in that, The release agent is selected from calcium stearate, magnesium stearate, or zinc stearate.

5. A method for preparing a high-temperature resistant, ceramic-compatible silicone resin composite material as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Modified boron carbide, talc powder, low melting point glass powder I and low melting point glass powder II are mixed evenly to obtain a mixed filler; methyl phenyl silicone resin is preheated to a molten state to obtain molten methyl phenyl silicone resin; (2) The mixed filler is added to the molten methylphenyl silicone resin in batches for the first physical blending, and then a curing agent and a release agent are added for the second physical blending. After the blending is completed, the mixture is cooled, crushed and molded to obtain the high-temperature resistant and ceramic-compatible silicone resin composite material.

6. The preparation method according to claim 5, characterized in that, In step (1), the preheating temperature is 110~120℃; and / or, In step (2), the first physical blending time is 20-30 minutes and the rotation speed is 50-200 rpm; the second physical blending time is 5-15 minutes and the rotation speed is 50-200 rpm.

7. The preparation method according to claim 5, characterized in that, In step (2), the molding process is as follows: first, hot press at 180℃ and 15MPa for 10~30 minutes, and then cure at 200℃ for 4 hours.

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