Preparation method of high-density graphite-based heat-dissipation and heat-proof composite material

Abstract

The application relates to a preparation method of a high-density graphite-based dissipation heat-resistant composite material. In order to solve the problems of high cost of the existing dissipation heat-resistant composite material and poor ablation resistance of the graphite dissipation heat-resistant composite material, the preparation method comprises the following steps: mixing multi-element dissipation agent raw materials, uniformly mixing the multi-element dissipation agent raw materials, loading the multi-element dissipation agent raw materials into a graphite crucible, processing a high-density graphite base into a shape to be prepared, mounting the high-density graphite base on a lifting rod of a vacuum infiltration furnace, preparing a dissipation agent alloy melt, and immersing the graphite base in the dissipation agent alloy melt to obtain the high-density graphite-based dissipation heat-resistant composite material. The high-density graphite-based dissipation heat-resistant composite material is prepared by using the vacuum infiltration method, high-purity graphite is used as the base, the composition of the dissipation agent alloy is adjusted, the dissipation agent is wetted with the graphite base, and the ablation resistance of the workpiece is improved. The application can be used for preparing aircraft engine nozzle throat liners, aircraft nose cones and wing leading edges and the like components.

Description

Technical Field

[0001] This invention is applicable to the field of lightweight ablation-resistant materials, and specifically relates to a method for preparing a graphite-based dissipative heat-resistant composite material. Background Technology

[0002] With the continuous development of aerospace, the working conditions at locations such as the nose cone, engine throat liner, and leading edge of aircraft are becoming increasingly harsh, and the performance requirements for ablation-resistant materials are constantly increasing. The working environment of ablation-resistant materials is usually above 3000℃, accompanied by severe particle erosion. The shape of ablation-resistant materials has a significant impact on the flight accuracy of aircraft, which requires them to have good ablation resistance, good mechanical properties and thermal shock resistance, as well as low density.

[0003] Dissipative heat-resistant materials are a class of materials infiltrating porous materials such as graphite and carbon-carbon composites using carbides, borides, and other substances with lower Gibbs free energy of oxidation than the matrix as dissipative agents. During ablation, these substances react with oxygen first, consuming oxygen on the workpiece surface and forming oxygen dissipation. Simultaneously, they absorb heat from the workpiece surface during liquefaction and vaporization, forming heat dissipation. Furthermore, the dense oxide ceramic layer formed on the workpiece surface by the dissipative agent effectively isolates the matrix from the oxidizing atmosphere, preventing oxygen diffusion into the matrix and providing excellent resistance to particle erosion, thus maintaining the workpiece's shape. The combined effect of these factors results in excellent ablation resistance in dissipative heat-resistant composite materials. While carbon-carbon porous materials are costly and have long preparation cycles, graphite exhibits good high-temperature mechanical properties. However, graphite is prone to oxidation above 500℃, resulting in low strength and poor resistance to particle erosion. Therefore, matrix modification of graphite is necessary to improve its ablation resistance. Summary of the Invention

[0004] In order to solve the problems of high cost and poor ablation resistance of existing dissipative heat-resistant composite materials, this invention proposes a method for preparing a high-density graphite-based dissipative heat-resistant composite material.

[0005] The preparation method of the high-density graphite-based dissipative heat-resistant composite material of the present invention is carried out according to the following method:

[0006] 1. Weigh out the raw materials of the multi-component dissipative agent, mix them evenly, and then put them into a graphite crucible;

[0007] The atomic ratio of silicon, boron, aluminum, molybdenum and zirconium in the multi-element dissipative agent is (10-18):(0-4):(0-4):(0-4):(0-4), and the multi-element dissipative agent contains at least three of boron, aluminum, molybdenum and zirconium.

[0008] 2. The high-density graphite matrix is ​​processed into the desired shape, and then ultrasonically cleaned and dried. After the sample is dried, a release agent is sprayed on the surface and dried. Finally, the high-density graphite matrix is ​​installed on the lifting rod of the vacuum melting furnace.

[0009] 3. Place the graphite crucible from step 1 under the high-density graphite matrix in the vacuum melting furnace;

[0010] 4. Close the vacuum melting furnace door and evacuate to a vacuum level of 1.0 × 10⁻⁶. -3 Below Pa, the vacuum melting furnace begins to heat up. After heating for 10 minutes, argon gas is introduced as a protective gas. Then, the temperature of the vacuum melting furnace is raised to 100-200°C above the melting point of the multi-element dissipant and held for 10-30 minutes to obtain the dissipant alloy melt. The lifting rod is lowered to immerse the high-density graphite matrix in the dissipant alloy melt and held for 10-20 minutes. Then, the lifting rod is raised to raise the high-density graphite matrix above the surface of the dissipant alloy melt. The power is turned off and the furnace is cooled to obtain a high-density graphite-based dissipative heat-resistant composite material.

[0011] The beneficial effects of this invention are as follows:

[0012] 1. This invention utilizes a vacuum melt infiltration method to prepare a high-density graphite-based dissipative heat-resistant composite material. This invention selects graphite with a density greater than 1.8 g / cm³. 3 Using high-purity graphite with a strength greater than 70 MPa as the matrix, and adjusting the composition of the dissipative alloy to ensure good wettability between the dissipative and the graphite matrix, capillary force is used to penetrate the molten dissipative alloy into the pores of the graphite matrix, enabling the low-cost fabrication of complex-shaped workpieces in a short period. In the ablation process, the high-density graphite-based dissipative heat-resistant composite material prepared by this invention allows aluminum, silicon, boron, molybdenum, and zirconium to react with oxygen before carbon, forming an oxide ceramic layer. Zirconia, with its high melting point, forms a high-strength framework. Silica, aluminum oxide, and boron oxide are liquid during ablation and can combine with zirconium dioxide to form a dense oxide ceramic film, protecting the matrix from thermochemical corrosion, improving the material's resistance to particle erosion, and enhancing the workpiece's ablation resistance.

[0013] 2. The present invention utilizes vacuum melting infiltration to prepare high-density graphite dissipative heat-resistant composite materials. The preparation cycle is short and the process is simple. The prepared materials have good mechanical properties, ablation resistance, and high density. They can be processed into workpieces with complex shapes, or they can be machined after preparation.

[0014] 3. The density of the high-density graphite dissipative heat-resistant composite material prepared by this invention is 2.4 g / cm³. 3 ~2.5g / cm 3It is a lightweight material, and its mechanical properties are 100 MPa stronger in three-point bending strength than the graphite matrix before impregnation, reaching the mechanical properties of carbon-carbon materials. After 60 s of ablation with an oxyacetylene flame at a heat flux density of 4.2 MW, the linear ablation rate decreased from 30 μm / s of the matrix to 1 μm / s.

[0015] 4. The high-density graphite dissipative heat-resistant composite material prepared by this invention can be used to prepare components such as the nozzle throat liner and gas rudder of aircraft engine, the nose cone and wing leading edge of aircraft, and the steering orifice plate of missile. Attached Figure Description

[0016] Figure 1 A scanning image of the graphite-based dissipative heat-resistant composite material prepared in Example 1;

[0017] Figure 2 The image shows the surface morphology of the graphite-based dissipative heat-resistant composite material prepared in Example 2 after ablation. Detailed Implementation

[0018] The technical solution of the present invention is not limited to the specific embodiments listed below, but also includes any reasonable combination of the specific embodiments.

[0019] Specific Implementation Method 1: The preparation method of the high-density graphite-based dissipative heat-resistant composite material in this implementation method is as follows:

[0020] 1. Weigh out the raw materials of the multi-component dissipative agent, mix them evenly, and then put them into a graphite crucible;

[0021] The atomic ratio of silicon, boron, aluminum, molybdenum and zirconium in the multi-element dissipative agent is (10-18):(0-4):(0-4):(0-4):(0-4), and the multi-element dissipative agent contains at least three of boron, aluminum, molybdenum and zirconium.

[0022] 2. The high-density graphite matrix is ​​processed into the desired shape, and then ultrasonically cleaned and dried. After the sample is dried, a release agent is sprayed on the surface and dried. Finally, the high-density graphite matrix is ​​installed on the lifting rod of the vacuum melting furnace.

[0023] 3. Place the graphite crucible from step 1 under the high-density graphite matrix in the vacuum melting furnace;

[0024] 4. Close the vacuum melting furnace door and evacuate to a vacuum level of 1.0 × 10⁻⁶. -3Below Pa, the vacuum melting furnace begins to heat up. After heating for 10 minutes, argon gas is introduced as a protective gas. Then, the temperature of the vacuum melting furnace is raised to 100-200°C above the melting point of the multi-element dissipant and held for 10-30 minutes to obtain the dissipant alloy melt. The lifting rod is lowered to immerse the high-density graphite matrix in the dissipant alloy melt and held for 10-20 minutes. Then, the lifting rod is raised to raise the high-density graphite matrix above the surface of the dissipant alloy melt. The power is turned off and the furnace is cooled to obtain a high-density graphite-based dissipative heat-resistant composite material.

[0025] The beneficial effects of this embodiment are:

[0026] 1. This embodiment utilizes a vacuum melt infiltration method to prepare a high-density graphite-based dissipative heat-resistant composite material. This embodiment selects graphite with a density greater than 1.8 g / cm³. 3 High-purity graphite with a strength greater than 70 MPa is used as the matrix. The composition of the dissipative alloy is adjusted to ensure good wettability between the dissipative and the graphite matrix. Then, capillary force is used to infiltrate the molten dissipative alloy into the pores of the graphite matrix, allowing for the low-cost fabrication of complex-shaped workpieces within a short period. In the ablation process, the high-density graphite-based dissipative heat-resistant composite material prepared in this embodiment exhibits the following properties: aluminum, silicon, boron, molybdenum, and zirconium react with oxygen before carbon to form an oxide ceramic layer. Zirconia, with its high melting point, forms a high-strength framework. Silica, aluminum oxide, and boron oxide are liquid during ablation and can combine with zirconium dioxide to form a dense oxide ceramic film, protecting the matrix from thermochemical corrosion, improving the matrix's resistance to particle erosion, and enhancing the workpiece's ablation resistance.

[0027] 2. This embodiment utilizes vacuum melting infiltration to prepare high-density graphite dissipative heat-resistant composite materials. The preparation cycle is short, the process is simple, and the prepared materials have good mechanical properties, ablation resistance, and high density. They can be processed into workpieces with complex shapes, or they can be machined after preparation.

[0028] 3. The density of the high-density graphite dissipative heat-resistant composite material prepared in this embodiment is 2.4 g / cm³. 3 ~2.5g / cm 3 It is a lightweight material, and its mechanical properties are 100 MPa stronger in three-point bending strength than the graphite matrix before impregnation, reaching the mechanical properties of carbon-carbon materials. After 60 s of ablation with an oxyacetylene flame at a heat flux density of 4.2 MW, the linear ablation rate decreased from 30 μm / s of the matrix to 1 μm / s.

[0029] 4. The high-density graphite dissipative heat-resistant composite material prepared in this embodiment can be used to prepare components such as the nozzle throat liner and gas rudder of aircraft engine, the nose cone and wing leading edge of aircraft, and the steering orifice plate of missile.

[0030] Specific Implementation Method Two: This implementation method differs from Specific Implementation Method One in that the atomic ratio of silicon, boron, aluminum, molybdenum, and zirconium in the multi-element dissipative agent described in step one is 18:2:2:1:1.

[0031] Specific Implementation Method 3: This implementation method differs from Specific Implementation Method 1 or 2 in that the raw materials mentioned in step 1 are aluminum powder, silicon powder, boron powder, molybdenum powder, and zirconium disilicide powder.

[0032] Specific Implementation Method Four: This implementation method differs from one of Specific Implementation Methods One to Three in that the particle size of the aluminum powder, silicon powder, boron powder, molybdenum powder, and zirconium disilicide powder mentioned in step one is less than 3 mm.

[0033] Specific Implementation Method Five: This implementation method differs from Specific Implementation Methods One to Four in that the density of the high-density graphite matrix described in step two is greater than 1.8 g / cm³. 3 The porosity is 10%–15%, and the three-point bending strength is greater than 70 MPa.

[0034] Specific Implementation Method Six: This implementation method differs from one of the specific implementation methods one to five in that the ultrasonic cleaning time in step two is 10 minutes.

[0035] Specific Implementation Method Seven: This implementation method differs from Specific Implementation Methods One to Six in that the drying time in step two is 30 min to 2 h, and the temperature is 80℃ to 100℃.

[0036] Specific Implementation Method Eight: This implementation method differs from one of the specific implementation methods one to seven in that the graphite crucible described in step three is located 100mm to 200mm below the high-density graphite matrix.

[0037] Specific Implementation Method Nine: This implementation method differs from Specific Implementation Methods One to Eight in that the argon gas introduced in step four is pressurized to 1 atm inside the furnace.

[0038] Specific Implementation Method 10: This implementation method differs from Specific Implementation Methods 1 to 9 in that the heating rate in step 4 is 30℃ / min.

[0039] Example 1

[0040] The high-density graphite-based dissipative heat-resistant composite material of this embodiment is prepared according to the following method:

[0041] 1. Weigh out the raw materials of the multi-component dissipative agent, mix them evenly, and then put them into a graphite crucible;

[0042] The atomic ratio of silicon, boron, aluminum, molybdenum and zirconium in the multi-component dissipative agent is 18:2:2:1:1;

[0043] The raw materials are aluminum powder, silicon powder, boron powder, molybdenum powder, and zirconium disilicide powder;

[0044] The particle size of the aluminum powder, silicon powder, boron powder, molybdenum powder, and zirconium disilicide powder is less than 3 mm.

[0045] 2. The high-density graphite matrix is ​​processed into the desired shape, and then ultrasonically cleaned and dried. After the sample is dried, a release agent is sprayed on the surface and dried. Finally, the high-density graphite matrix is ​​installed on the lifting rod of the vacuum melting furnace.

[0046] The density of the high-density graphite matrix is ​​1.90 g / cm³. 3 The porosity is 12%, and the three-point bending strength is greater than 70 MPa;

[0047] The ultrasonic cleaning time is 10 minutes;

[0048] The drying time is 30 minutes and the temperature is 80°C;

[0049] 3. Place the graphite crucible from step 1 under the high-density graphite matrix in the vacuum melting furnace;

[0050] The graphite crucible is located 100 mm below the high-density graphite matrix;

[0051] 4. Close the vacuum melting furnace door and evacuate to a vacuum level of 1.0 × 10⁻⁶. -3 Pa, the vacuum melting furnace starts to heat up, and after heating for 10 minutes, argon gas is introduced as a protective gas; then the temperature of the vacuum melting furnace is raised to 1600 and held for 10 minutes to obtain the dissipant alloy melt; the lifting rod is lowered to immerse the high-density graphite matrix in the dissipant alloy melt, and held for 10 minutes, then the lifting rod is raised to raise the high-density graphite matrix to 100 mm above the surface of the dissipant alloy melt, the power is turned off, the furnace is cooled, and a high-density graphite-based dissipative heat-resistant composite material is obtained;

[0052] In step four, argon gas is introduced until the pressure inside the furnace is 1 atm.

[0053] The heating rate described in step four is 20°C / min;

[0054] The high-density graphite-based dissipative heat-resistant composite material prepared in Example 1 has a density of 2.4 g / cm³. 3 The weight increase was 26.3% compared to the matrix; the thermal conductivity was 91.18 W / (mK), an increase of 30.95% compared to the matrix (74.97 W / (mK)); the three-point bending strength increased from 74.72 MPa of the matrix to 176.94 MPa, reaching some of the mechanical properties of carbon-carbon composite materials. Figure 1 The SEM image of the prepared graphite-based dissipative heat-resistant composite material shows that the graphite pores have been filled with alloy. The graphite-based dissipative heat-resistant composite material prepared in Example 1 exhibits a performance of 4.2 MW / mm². 2In the oxyacetylene flame test, after 60 seconds of ablation, the linear ablation rate decreased from 30 μm / s of the substrate to 1 μm / s.

[0055] Example 2

[0056] The high-density graphite-based dissipative heat-resistant composite material of this embodiment is prepared according to the following method:

[0057] 1. Weigh out the raw materials of the multi-component dissipative agent, mix them evenly, and then put them into a graphite crucible;

[0058] The atomic ratio of silicon, aluminum, boron, and zirconium in the multi-component dissipative agent is 9:2:1:1;

[0059] The raw materials are aluminum powder, silicon powder, boron powder and zirconium disilicide powder;

[0060] The particle size of the aluminum powder, silicon powder, boron powder and zirconium disilicide powder is less than 3 mm;

[0061] 2. The high-density graphite matrix is ​​processed into the desired shape, and then ultrasonically cleaned and dried. After the sample is dried, a release agent is sprayed on the surface and dried. Finally, the high-density graphite matrix is ​​installed on the lifting rod of the vacuum melting furnace.

[0062] The density of the high-density graphite matrix is ​​1.90 g / cm³. 3 The porosity is 12%, and the three-point bending strength is greater than 70 MPa;

[0063] The ultrasonic cleaning time is 10 minutes;

[0064] The drying time is 30 minutes and the temperature is 80°C;

[0065] 3. Place the graphite crucible from step 1 under the high-density graphite matrix in the vacuum melting furnace;

[0066] The graphite crucible is located 100 mm below the high-density graphite matrix;

[0067] 4. Close the vacuum melting furnace door and evacuate to a vacuum level of 1.0 × 10⁻⁶. -3 Below Pa, the vacuum melting furnace begins to heat up. After heating for 10 minutes, argon gas is introduced as a protective gas. Then, the temperature of the vacuum melting furnace is raised to 1700℃ and held for 10 minutes to obtain the dissipant alloy melt. The lifting rod is lowered to immerse the high-density graphite matrix in the dissipant alloy melt and held for 10 minutes. Then, the lifting rod is raised to raise the high-density graphite matrix to 50 mm above the surface of the dissipant alloy melt. The power is turned off and the furnace is cooled to obtain a high-density graphite-based dissipative heat-resistant composite material.

[0068] In step four, argon gas is introduced until the pressure inside the furnace is 1 atm.

[0069] The heating rate described in step four is 30℃ / min;

[0070] The graphite-based dissipative heat-resistant composite material prepared in Example 2 has a density of 2.39 g / cm³. 3 The weight increase was 25.7% compared to the matrix; the thermal conductivity was 90.06 W / (mK), an increase of 20.12% compared to the matrix's 74.97 W / (mK); the three-point bending strength was 175 MPa, significantly higher than that of the high-density graphite matrix (74.72 MPa). According to GJB 323A-96, oxyacetylene ablation experiments were conducted. Under oxyacetylene ablation conditions, after 90 s of ablation, the linear ablation rate was only 0.68 μm / s. Figure 2 This is a surface morphology image after 90 seconds of ablation.

Claims

1. A method for preparing a high-density graphite-based dissipative heat-resistant composite material, characterized in that: The preparation method of high-density graphite-based dissipative heat-resistant composite material is as follows:

1. Weigh out the raw materials of the multi-component dissipative agent, mix them evenly, and then put them into a graphite crucible; The atomic ratio of silicon, boron, aluminum, molybdenum, and zirconium in the multi-component dissipative agent is 18:2:2:1:1; The raw materials are aluminum powder, silicon powder, boron powder, molybdenum powder, and zirconium disilicide powder; The particle size of the aluminum powder, silicon powder, boron powder, molybdenum powder, and zirconium disilicide powder is less than 3 mm.

2. The high-density graphite matrix is ​​processed into the desired shape, and then ultrasonically cleaned and dried. After the sample is dried, a release agent is sprayed on the surface and dried. Finally, the high-density graphite matrix is ​​installed on the lifting rod of the vacuum melting furnace. The density of the high-density graphite matrix is ​​1.90 g / cm³. 3 The porosity is 12%, and the three-point bending strength is greater than 70 MPa; The ultrasonic cleaning time is 10 minutes; The drying time is 30 minutes and the temperature is 80°C; 3. Place the graphite crucible from step 1 under the high-density graphite matrix in the vacuum melting furnace; The graphite crucible is located 100 mm below the high-density graphite matrix; 4. Close the vacuum melting furnace door and evacuate to a vacuum level of 1.0 × 10⁻⁶. -3 Pa, the vacuum melting furnace starts to heat up, and after heating for 10 minutes, argon gas is introduced as a protective gas; then the temperature of the vacuum melting furnace is raised to 1600 and held for 10 minutes to obtain the dissipant alloy melt; the lifting rod is lowered to immerse the high-density graphite matrix in the dissipant alloy melt, and held for 10 minutes, then the lifting rod is raised to raise the high-density graphite matrix to 100 mm above the surface of the dissipant alloy melt, the power is turned off, the furnace is cooled, and a high-density graphite-based dissipative heat-resistant composite material is obtained; In step four, argon gas is introduced until the pressure inside the furnace is 1 atm. The heating rate described in step four is 20°C / min; The density of the prepared high-density graphite-based dissipative heat-resistant composite material is 2.4 g / cm³. 3 The thermal conductivity is 91.18 W / (mK), and the three-point bending strength is 176.94 MPa.

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