Aluminum silicon carbide composite material and method of making same

Abstract

The application discloses an aluminum silicon carbide composite material and a preparation method thereof, and the method comprises the following steps: mixing boron-silicon fine powder and large-size silicon carbide particles to obtain large-size mixed material W1; mixing boron-silicon fine powder and small-size silicon carbide particles to obtain small-size mixed material W2; mixing the large-size mixed material W1 and paraffin to obtain material W3; mixing the small-size mixed material W2 and paraffin to obtain material W4; granulating the material W3 and the material W4 respectively to obtain material W5 and material W6; laying the material W5 and the material W6 in a sandwich structure, dry-pressing the sandwich structure to obtain a green body P0 of the sandwich structure; sintering the green body P0 to obtain a preform P1 of the silicon carbide-based porous ceramic with the sandwich structure; and infiltrating aluminum alloy into the preform P1 to obtain the aluminum silicon carbide composite material. The application solves the technical problems of low aluminum liquid infiltration and low physical and chemical performance of the composite material in the preparation of the high-thickness aluminum silicon carbide substrate by using the existing low-pressure vacuum infiltration method.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of new material preparation and packaging heat dissipation, and particularly relates to an aluminum silicon carbide composite material and a preparation method thereof. BACKGROUND

[0002] The aluminum silicon carbide composite material is a third-generation electronic packaging heat dissipation material, which is a non-oxide-metal composite material with high specific stiffness, adjustable thermal expansion coefficient and high thermal conductivity, and is used to solve the thermal failure problem of chips, transistors or semiconductors caused by high integration of electronic circuits. Compared with the preparation methods of powder metallurgy, stirring casting and pressure casting, the low-pressure vacuum infiltration method has the advantages of low cost, simple process, near net shape of the composite material, small internal stress and preparation of high aluminum silicon carbide material. Factors affecting the preparation of aluminum silicon carbide substrate / structural parts by low-pressure vacuum infiltration: 1, pressure difference between upper and lower cavities; 2, wettability between aluminum liquid and silicon carbide ceramic preform; 3, pore size and distribution of the silicon carbide ceramic preform. However, when the low-pressure vacuum infiltration method is used to prepare high-thickness (such as 20-30mm) aluminum silicon carbide substrates or structural parts, the aluminum liquid often fails to penetrate, and the physical and chemical properties of the composite material are low, thereby limiting the application of this method in the field of high-thickness aluminum silicon carbide substrates / structural parts. SUMMARY

[0003] In view of the deficiencies of the prior art, the purpose of the present application is to provide an aluminum silicon carbide composite material and a preparation method thereof, which solves the technical problems of low penetration of aluminum liquid and low physical and chemical and mechanical properties of the composite material when the existing low-pressure vacuum infiltration method is used to prepare high-thickness aluminum silicon carbide substrates.

[0004] The application adopts the following technical scheme:

[0005] A preparation method of an aluminum silicon carbide composite material, comprising the following processes:

[0006] Mixing boron-silicon fine powder and large-particle-size silicon carbide particles to obtain large-particle-size mixed material W1; mixing boron-silicon fine powder and small-particle-size silicon carbide particles to obtain small-particle-size mixed material W2; the particle size of the large-particle-size silicon carbide particles is larger than that of the small-particle-size silicon carbide particles;

[0007] Mixing the large-particle-size mixed material W1 with paraffin to obtain material W3; mixing the small-particle-size mixed material W2 with paraffin to obtain material W4;

[0008] Granulating the material W3 to obtain material W5; granulating the material W4 to obtain material W6;

[0009] Laying the sandwich structure by using the material W5 and the material W6, and drying and pressing the sandwich structure to obtain a green body P0 of the sandwich structure; wherein when laying the material, the material W5 is used to lay the middle layer of the sandwich structure, and the material W6 is used to lay the upper layer and the lower layer of the sandwich structure;

[0010] Sintering the green body P0 to obtain a preform P1 of the silicon carbide-based porous ceramic with a sandwich structure;

[0011] Impregnating the preform P1 with an aluminum alloy to obtain the aluminum silicon carbide composite material.

[0012] Preferably, in the large-particle-size mixture W1, the mass ratio of the silicon carbide particles to the borosilicon fine powder is 100:(1.5-2);

[0013] In the small-particle-size mixture W2, the mass ratio of the silicon carbide particles to the borosilicon fine powder is 100:(1.5-2);

[0014] The large-particle-size silicon carbide particles have a mesh number of 100-200 meshes, and 80 μm 50 <100 μm;

[0015] The small-particle-size silicon carbide particles have a mesh number of 400-600 meshes, and 30 μm 50 <40 μm;

[0016] The composition of the large-particle-size silicon carbide particles and the small-particle-size silicon carbide particles satisfies w(SiC)≥98%;

[0017] The particle size of the borosilicon fine powder is 0.3 μm 50 <0.8 μm, and the composition of the borosilicon fine powder satisfies 25%≤w(B2O3)≤30% and 70%≤w(SiO2)≤75%.

[0018] Preferably, when mixing the large-particle-size mixture W1 with paraffin to obtain the material W3, the mass ratio of the material W1 to the paraffin is 100:(6-10), the temperature is 110-120°C, and the time is 2-4 h;

[0019] When mixing the small-particle-size mixture W2 with paraffin to obtain the material W4, the mass ratio of the material W2 to the paraffin is 100:(6-10), the temperature is 110-120°C, and the time is 2-4 h.

[0020] Preferably, the mesh number of the material W5 is less than or equal to 80 meshes, and the mesh number of the material W6 is less than or equal to 80 meshes.

[0021] Preferably, when laying the sandwich structure by using the material W5 and the material W6, the mass ratio of the upper layer, the middle layer and the lower layer is (7-11):(6-8):(7-11);

[0022] When laying the sandwich structure by using the material W5 and the material W6, the material W6 is laid in the mold to form a lower layer, the lower layer is scraped flat, then the material W5 is laid on the lower layer to form an intermediate layer, the intermediate layer is scraped flat, then the material W6 is laid on the intermediate layer to form an upper layer, and the upper layer is scraped flat, so that the sandwich structure is obtained.

[0023] Preferably, when the sandwich structure is subjected to dry pressing, the axial pressure is 2-5 MPa, and the pressure holding time is 5-15 s.

[0024] Preferably, when the green body P0 is subjected to sintering, the sintering temperature is 1050-1150℃, and the sintering time is 20 min-35 min.

[0025] The specific process of heating during sintering includes:

[0026] Rising from 0℃ to 200℃, taking 2-3h; rising from 200℃ to 400℃, taking 2-4h; keeping at 400℃ for 3-6h; rising from 400℃ to 600℃, taking 2-3h; keeping at 600℃ for 4-5h; rising from 600℃ to the sintering temperature, taking 2-2.5h.

[0027] Preferably, when the preform P1 is impregnated with aluminum alloy, the aluminum alloy is a quenched and tempered aluminum alloy, and the impregnation process specifically includes:

[0028] The preform P1 is placed in the mold and preheated together to 690-710℃;

[0029] The ZL101 aluminum alloy is melted, when the temperature of the ZL101 aluminum alloy liquid reaches 670-690℃, magnesium is added to the ZL101 aluminum alloy liquid, and then heated together to 690-710℃ and the magnesium is melted, so that the quenched and tempered aluminum alloy is obtained, wherein the mass of the added magnesium is 0.5wt%-0.7wt% of the mass of the ZL101 aluminum alloy liquid;

[0030] The preheated preform P1 and the mold are impregnated with the quenched and tempered aluminum alloy in a protective atmosphere vacuum pressure impregnation furnace, the vacuum degree of the protective atmosphere vacuum pressure impregnation furnace is -90pa, the impregnation pressure is 1.5-3MPa, and the pressure holding time is 15-20min.

[0031] The application further provides an aluminum silicon carbide composite material prepared by the preparation method.

[0032] Preferably, the physicochemical parameters of the aluminum silicon carbide composite material are as follows:

[0033] The volume percentage of silicon carbide-based porous ceramic preform to aluminum alloy in aluminum-silicon carbide composite material is (50-70): (30-50), the porosity of silicon carbide-based porous ceramic preform is 30%-50%, and the three-point bending strength of silicon carbide-based porous ceramic is greater than 6MPa.

[0034] The aluminum-silicon carbide composite material has a volume fraction greater than 99.5% and a density less than 3.5 g / cm³. 3 The three-point bending strength is 340-380 MPa, the thermal conductivity is greater than 195 W / m·K, and the coefficient of thermal expansion is less than 7.5 ppm / ℃;

[0035] The thickness of the aluminum silicon carbide composite material is 20-30 mm.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] In the preparation method of this invention, silicon carbide particles of two sizes, large and small, are used. During the material distribution, materials of large-small-large particle sizes are stacked sequentially from bottom to middle to top to obtain a sandwich structure. The sandwich structure preform is then sintered to obtain a preform of silicon carbide-based porous ceramic with a sandwich structure. In the preform of silicon carbide-based porous ceramic with a sandwich structure, the pore size is distributed in a state where the upper and lower layers are large and the middle layer is small. The preform of silicon carbide-based porous ceramic with a sandwich structure forms a capillary effect from bottom to middle and top to middle, which makes it easy for aluminum alloy liquid to penetrate into the middle layer from the upper and lower layers. This makes the entire silicon carbide-based porous ceramic preform easy to be penetrated by aluminum alloy liquid, thereby improving the physical, chemical and mechanical properties of the aluminum silicon carbide composite material. This results in a high-thickness aluminum silicon carbide substrate / structure with excellent performance and high density, breaking the limitation of the application of low-pressure vacuum impregnation method in the field of high-thickness aluminum silicon carbide substrate / structure.

[0038] Furthermore, the aluminum alloy used in this invention is a tempered aluminum alloy, that is, pure magnesium is added to the ZL101 aluminum alloy liquid, which can increase the magnesium content in the ZL101 aluminum alloy liquid, reduce the surface tension of the ZL101 aluminum alloy liquid, reduce the wetting angle between the ZL101 aluminum alloy liquid and silicon carbide particles, which is beneficial for the aluminum to penetrate the entire silicon carbide-based porous ceramic preform. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the structure of the preform of silicon carbide-based porous ceramic with a sandwich structure obtained by the present invention;

[0040] Figure 2 The image shows the metallographic structure of the aluminum silicon carbide composite material with a sandwich structure obtained in Example 3 of this invention.

[0041] In the diagram, 1 is the top layer, 2 is the middle layer, and 3 is the bottom layer. Detailed Implementation

[0042] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0043] The preparation method of the aluminum silicon carbide composite material of the present invention includes the following steps:

[0044] S1. Sift the silicon carbide particles to obtain silicon carbide particles of 100-200 mesh and 400-600 mesh. The particle size of the 100-200 mesh silicon carbide particles is 80 μm. <D 50 <100μm, the particle size of silicon carbide particles with a mesh size of 400-600 is 30μm. <D 50 <40μm; the composition of the silicon carbide particles satisfies: w(SiC)≥98%; the particle size of the borosilicate powder is 0.3μm. <D 50 <0.8μm, the borosilicate fine powder composition meets the following requirements: 25%≤w(B2O3)≤30%, 70%≤w(SiO2)≤75%;

[0045] The 100-200 mesh silicon carbide particles and borosilicate fine powder are mixed in a medium-low speed horizontal mixer to obtain a large particle size mixture W1; wherein the rotation speed of the medium-low speed horizontal mixer is 300-500 r / min and the mixing time is 150 min-300 min; in the large particle size mixture W1, the mass ratio of silicon carbide particles to borosilicate fine powder is 100:(1.5-2).

[0046] The 400-600 mesh silicon carbide particles and borosilicate fine powder are mixed in a medium-low speed horizontal mixer to obtain a small particle size mixture W2; wherein the rotation speed of the medium-low speed horizontal mixer is 300-500 r / min and the mixing time is 150 min-300 min; in the small particle size mixture W2, the mass ratio of silicon carbide particles to borosilicate fine powder is 100:(1.5-2);

[0047] S2. Take the material W1 from step S1 and put it into a kneader at a mass ratio of 100:(6-10) and heat and knead to obtain material W3. The kneading temperature is 110-120℃ and the time is 2-4h.

[0048] S3. Take the material W2 from step S1 and put it into a kneader at a mass ratio of 100:(6-10) and heat and knead it to obtain material W4. The kneading temperature is 110-120℃ and the time is 2-4h.

[0049] S4. Take the material W3 from step S2 and pass it through a gyratory granulator to obtain material W5; take the material W4 from step S3 and pass it through a gyratory granulator to obtain material W6; wherein, the rotation speed of the gyratory granulator is 40-50 r / min and the screen is 80 mesh.

[0050] S5. Take materials W5 and W6 from step S4, place them in a dry pressing mold, and then dry press to obtain a blank P0. The material placement process is as follows: the material placement sequence is bottom → middle → top, stacking materials of large-small-large particle size in sequence. That is, first lay a layer of material W5 in the mold as the lower layer of the sandwich structure, then lay a layer of material W6 as the middle layer of the sandwich structure, and then lay a layer of material W5 as the upper layer of the sandwich structure. When placing each layer of material, scraper is used to smooth it. The mass ratio of the upper layer, middle layer and lower layer is (7-11):(6-8):(7-11). The axial pressure during dry pressing is 2-5MPa and the holding time is 5-15s.

[0051] S6. Take the preform P0 from step S5 and place it in a resistance furnace for sintering to obtain a silicon carbide-based porous ceramic preform P1 with a sandwich structure; wherein the specific heating process during sintering includes:

[0052] The heating process involves raising the temperature from 0℃ to 200℃ in 2-3 hours; raising the temperature from 200℃ to 400℃ in 2-4 hours; holding the temperature at 400℃ for 3-6 hours; raising the temperature from 400℃ to 600℃ in 2-3 hours; holding the temperature at 600℃ for 4-5 hours; and raising the temperature from 600℃ to the sintering temperature of 1050-1150℃ in 2-2.5 hours, holding the temperature at the sintering temperature for 20-35 minutes.

[0053] S7. Take the silicon carbide-based porous ceramic preform P1 obtained in step S6, place it into a graphite mold, and then put them together into a pit-type resistance furnace for preheating; wherein, the thickness of the graphite mold is 25-35mm.

[0054] S8. Place the silicon carbide-based porous ceramic preform P1, which has been preheated in step S7, into a graphite mold and place the whole thing in a resistance vacuum pressure impregnation furnace under a protective atmosphere to impregnate aluminum alloy, thereby obtaining an aluminum silicon carbide composite material preform P2, which is the aluminum silicon carbide composite material of the present invention.

[0055] In a preferred embodiment of the present invention, in S8, the protective atmosphere is nitrogen or argon, preferably nitrogen. When nitrogen is used as the protective atmosphere, the purity of nitrogen is ≥99.999%, and the vacuum degree in the nitrogen atmosphere vacuum pressure impregnation furnace is -90 Pa.

[0056] As a preferred embodiment of the present invention, in the above technical solution, the aluminum alloy liquid used for impregnation is a quenched and tempered aluminum alloy, which is prepared by ZL101 aluminum alloy and magnesium. The specific preparation process is as follows: ZL101 aluminum alloy is melted, and when the temperature of the ZL101 aluminum alloy liquid reaches 670-690℃, magnesium is added to the ZL101 aluminum alloy liquid, and then heated together to 690-710℃ to melt the magnesium, thereby obtaining the quenched and tempered aluminum alloy. Correspondingly, in step S7, the preheating temperature of the silicon carbide-based porous ceramic preform P1 is 690-710℃.

[0057] As a preferred embodiment of the present invention, in the above embodiment, the purity of magnesium is ≥99.99%, and the mass of magnesium added is 0.5wt%-0.7wt% of the mass of ZL101 aluminum alloy liquid.

[0058] In a preferred embodiment of the present invention, the impregnation pressure is 1.5-3 MPa and the pressure holding time is 15-20 min.

[0059] As a preferred embodiment of the present invention, the blank P2 obtained in step S8 can also be processed by post-machining and sandblasting to obtain a high-thickness aluminum silicon carbide substrate / structural component P3. The machining methods can include wire cutting, milling, and / or grinding, and the sandblasting abrasive used is white corundum with a mesh size of 300.

[0060] The aluminum silicon carbide composite material prepared by the above preparation method of the present invention can reach a thickness of 20-30 mm. The main components of the aluminum silicon carbide composite material include a preform of silicon carbide-based porous ceramic with a sandwich structure and an aluminum alloy. The physicochemical parameters of the aluminum silicon carbide composite material meet the following requirements: the volume percentage of silicon carbide-based porous ceramic preform to aluminum alloy is (50-70):(30-50), the porosity of silicon carbide-based porous ceramic preform is 30%-50%, and the three-point bending strength of silicon carbide-based porous ceramic is greater than 6 MPa.

[0061] The aluminum-silicon carbide composite material has a volume fraction greater than 99.5% and a density less than 3.5 g / cm³. 3 The three-point bending strength is 340-380 MPa, the thermal conductivity is greater than 195 W / m·K, and the coefficient of thermal expansion is less than 7.5 ppm / ℃.

[0062] The above parameters were measured based on the following standards: density (porosity), pore size distribution, three-point bending strength, thermal conductivity, and coefficient of thermal expansion. The data were obtained from the following standards: "Test Method for Apparent Porosity and Bulk Density of Ceramic Green Body (QB / T 1642-2012)", "Test Method for Pore Diameter of Porous Ceramic Channels (GB / T 1967-1996)", "Stress-Strain Test Method (GB / T38978-2020)", "Measurement of Thermal Diffusion Coefficient or Thermal Conductivity by Flash Method (GBT 22588-2008)" and "Test Method for Linear Expansion System of Solid Materials (GJB 332A-2004)".

[0063] Example 1

[0064] The preparation method of the aluminum silicon carbide composite material in this embodiment specifically includes the following steps:

[0065] S1. Large-diameter silicon carbide particles and borosilicate powder are mixed at a mass ratio of 100:1.5. The mixture is then blended using a medium-low speed horizontal mixer at a speed of 300 r / min for 150 min. The resulting material is W1; wherein the particle size of the large-diameter silicon carbide particles is D. 50 =100μm, the composition of large-diameter silicon carbide particles satisfies: w(SiC) = 99.5%; the particle size of borosilicate fine powder is D 50 =0.8μm, the borosilicate fine powder composition satisfies: w(B2O3) = 25%, w(SiO2) = 75%.

[0066] S2. Small-diameter silicon carbide particles and borosilicate powder are mixed a second time at a mass ratio of 100:1.5 using a medium-low speed horizontal mixer. During mixing, the mixer speed is 300 r / min and the mixing time is 150 min. After mixing, material W2 is obtained; wherein the particle size of the small-diameter silicon carbide particles is D. 50 =40μm, the composition of small-diameter silicon carbide particles satisfies: w(SiC) = 99.5%; the particle size of borosilicate fine powder is D 50 =0.8μm, the borosilicate fine powder composition satisfies: w(B2O3) = 25%, w(SiO2) = 75%.

[0067] S3. Take the material W1 obtained in step S1 and paraffin wax and mix them in a mass ratio of material W1: paraffin wax = 100: 10 for the third time. Put material W1 and paraffin wax into a kneader and heat and mix them at a temperature of 110℃ for 2 hours to obtain material W3.

[0068] S4. Take the material W2 obtained in step S1 and paraffin wax and mix them in a mass ratio of material W2: paraffin wax = 100: 10 for the fourth time. Put the material W2 and paraffin wax into a kneader and heat and mix them at a temperature of 110℃ for 2 hours to obtain material W4.

[0069] S5. Take material W3 and place it in a gyratory granulator. After granulation through an 80-mesh sieve, material W5 is obtained. Take material W4 and place it in a gyratory granulator. After granulation through an 80-mesh sieve, material W6 is obtained.

[0070] S6. Take materials W5 and W6 from step S4, place them in a dry pressing mold, and then dry press to obtain a preform P0. The material placement process is as follows: the material placement sequence is bottom → middle → top, stacking materials of large-small-large particle size in sequence. That is, first lay a layer of material W5 in the mold as the lower layer of the sandwich structure, then lay a layer of material W6 as the middle layer of the sandwich structure, and then lay a layer of material W5 as the upper layer of the sandwich structure. Each layer of material is smoothed with a scraper during placement. The mass ratio of the upper layer, middle layer, and lower layer is 7:6:7. The axial pressure during dry pressing is 2MPa, and the holding time is 5s to obtain the preform P0.

[0071] S7. Place the preform P0 obtained in step S6 in a resistance furnace and sinter it to the target temperature using a programmed heating method to obtain a porous ceramic preform P1 with a "sandwich" structure; the specific heating process during sintering includes:

[0072] The process involves heating from 0℃ to 200℃ in 3 hours; heating from 200℃ to 400℃ in 4 hours; holding at 400℃ for 6 hours; heating from 400℃ to 600℃ in 2 hours; holding at 600℃ for 4 hours; and heating from 600℃ to the sintering temperature of 1050℃ in 2 hours, followed by holding at 1050℃ for 20 minutes.

[0073] S8. Place the porous ceramic preform P1 with a "sandwich" structure obtained in step S7 into a nitrogen atmosphere vacuum pressure impregnation furnace, and program it to the target parameters to obtain an aluminum silicon carbide-based composite material preform P2. Specifically, the vacuum degree in the nitrogen atmosphere vacuum pressure impregnation furnace is -90 Pa, the temperature of the ZL101 aluminum alloy liquid is 690℃, the purity of nitrogen is ≥99.999%, the purity of magnesium is ≥99.99%, the amount of magnesium added is 0.5% of the mass of ZL101 aluminum alloy, the temperature of the ZL101 aluminum alloy liquid when magnesium is added is 670℃, the impregnation pressure is 1.5 MPa, and the holding time is 15 min to obtain the aluminum silicon carbide-based composite material preform P2.

[0074] S9. After the aluminum silicon carbide-based composite material preform P2 obtained in step S8 is subjected to machining processes such as wire cutting, milling, and grinding, the surface is sandblasted with 300-mesh white corundum sand to obtain aluminum silicon carbide-based product P3.

[0075] The aluminum silicon carbide composite material obtained in this embodiment has a thickness of 20 mm and a sandwich structure. The physicochemical parameters meet the following requirements: the volume percentage of silicon carbide-based porous ceramic preform to aluminum alloy is 50:50; the porosity of silicon carbide-based porous ceramic preform is 50%; and the three-point bending strength of silicon carbide-based porous ceramic is 6 MPa.

[0076] The aluminum-silicon carbide composite material has a volume fraction of 99.5% and a density of 2.93 g / cm³. 3 The three-point bending strength is 320MPa, the thermal conductivity is 185W / m·K, and the coefficient of thermal expansion is 9ppm / ℃.

[0077] Example 2

[0078] The preparation method of the aluminum silicon carbide composite material in this embodiment specifically includes the following steps:

[0079] S1. Large-diameter silicon carbide particles and borosilicate powder are mixed at a mass ratio of 100:1.8. The mixture is then blended using a medium-low speed horizontal mixer at a speed of 400 r / min for 200 min. The resulting material is W1; wherein the particle size of the large-diameter silicon carbide particles is D. 50 =90μm, the composition of large-diameter silicon carbide particles satisfies: w(SiC) = 99.5%; the particle size of borosilicate fine powder is D 50 =0.6μm, the borosilicate fine powder composition satisfies: w(B2O3) = 28%, w(SiO2) = 72%.

[0080] S2. Small-diameter silicon carbide particles and borosilicate powder are mixed a second time at a mass ratio of 100:1.8 using a medium-low speed horizontal mixer. During mixing, the mixer speed is 400 r / min and the mixing time is 200 min. After mixing, material W2 is obtained; wherein the particle size of the small-diameter silicon carbide particles is D. 50 =35μm, the composition of small-diameter silicon carbide particles satisfies: w(SiC) = 99.5%; the particle size of borosilicate fine powder is D 50 =0.6μm, the borosilicate fine powder composition satisfies: w(B2O3) = 28%, w(SiO2) = 72%.

[0081] S3. Take the material W1 obtained in step S1 and paraffin wax and mix them in a third batch according to the mass ratio: material W1 paraffin wax = 100: 8. Put the material W1 and paraffin wax into a kneader and heat and mix them. The mixing temperature is constant at 115℃ and the time is 3h to obtain material W3.

[0082] S4. Take the material W2 obtained in step S1 and paraffin wax and mix them in a mass ratio of material W2:paraffin wax = 100:8 for the fourth time. Put the material W1 and paraffin wax into a kneader and heat and mix them at a temperature of 115℃ for 3 hours to obtain material W4.

[0083] S5. Take material W3 and place it in a gyratory granulator. After granulation through an 80-mesh sieve, material W5 is obtained. Take material W4 and place it in a gyratory granulator. After granulation through an 80-mesh sieve, material W6 is obtained.

[0084] S6. Take materials W5 and W6 from step S4, place them in a dry pressing mold, and then dry press to obtain a preform P0. The material placement process is as follows: the material placement sequence is bottom → middle → top, stacking materials of large-small-large particle size in sequence. That is, first lay a layer of material W5 in the mold as the lower layer of the sandwich structure, then lay a layer of material W6 as the middle layer of the sandwich structure, and then lay a layer of material W5 as the upper layer of the sandwich structure. Each layer of material is smoothed with a scraper. The mass ratio of the upper, middle, and lower layers is 9:7:9. The axial pressure during dry pressing is 3.5 MPa, and the holding time is 10 s to obtain the preform P0.

[0085] S7. Place the preform P0 obtained in step S6 in a resistance furnace and sinter it to the target temperature using a programmed heating method to obtain a porous ceramic preform P1 with a "sandwich" structure; the specific heating process during sintering includes:

[0086] The heating process takes 2.5 hours to raise the temperature from 0℃ to 200℃; 3 hours to raise the temperature from 200℃ to 400℃; and 4.5 hours to hold the temperature at 400℃. The heating process also takes 2.5 hours to raise the temperature from 400℃ to 600℃; and 4.5 hours to hold the temperature at 600℃. The heating process takes 130 minutes to raise the temperature from 600℃ to the sintering temperature of 1100℃; and 25 minutes to hold the temperature at 1100℃.

[0087] S8. Place the porous ceramic preform P1 with a "sandwich" structure obtained in step S7 into a nitrogen atmosphere vacuum pressure impregnation furnace, and program it to the target parameters to obtain an aluminum silicon carbide-based composite material preform P2. Specifically, the vacuum degree in the nitrogen atmosphere vacuum pressure impregnation furnace is -90 Pa, the temperature of the ZL101 aluminum alloy liquid is 700℃, the purity of nitrogen is ≥99.999%, the purity of magnesium is ≥99.99%, the amount of magnesium added is 0.6% of the mass of ZL101 aluminum alloy, the temperature of the ZL101 aluminum alloy liquid when magnesium is added is 690℃, the impregnation pressure is 2 MPa, and the holding time is 17 min to obtain the aluminum silicon carbide-based composite material preform P2.

[0088] S9. After the aluminum silicon carbide-based composite material preform P2 obtained in step S8 is subjected to machining processes such as wire cutting, milling, and grinding, the surface is sandblasted with 300-mesh white corundum sand to obtain aluminum silicon carbide-based product P3.

[0089] The aluminum-silicon carbide composite material obtained in this embodiment has a thickness of 25 mm and a sandwich structure. The physicochemical parameters meet the following requirements: the volume percentage of silicon carbide-based porous ceramic preform to aluminum alloy is 65:35; the porosity of silicon carbide-based porous ceramic preform is 35%; and the three-point bending strength of silicon carbide-based porous ceramic is 7.5 MPa.

[0090] The aluminum-silicon carbide composite material has a volume fraction of 99.7% and a density of less than 3.01 g / cm³. 3 The three-point bending strength is 360MPa, the thermal conductivity is 197W / m·K, and the coefficient of thermal expansion is 8ppm / ℃.

[0091] Example 3

[0092] The preparation method of the aluminum silicon carbide composite material in this embodiment specifically includes the following steps:

[0093] S1. Large-diameter silicon carbide particles and borosilicate powder are mixed at a mass ratio of 100:2. The mixture is then blended using a medium-low speed horizontal mixer at a speed of 500 r / min for 300 min. The resulting material is W1; wherein the particle size of the large-diameter silicon carbide particles is D. 50 =80μm, the composition of large-diameter silicon carbide particles satisfies: w(SiC = 99.5%); the particle size of borosilicate fine powder is D 50 =0.3μm, the borosilicate fine powder composition satisfies: w(B2O3) = 30%, w(SiO2) = 70%.

[0094] S2. Small-diameter silicon carbide particles and borosilicate powder are mixed a second time at a mass ratio of 100:1.8 using a medium-low speed horizontal mixer. During mixing, the mixer speed is 500 r / min and the mixing time is 300 min. After mixing, material W2 is obtained; wherein the particle size of the small-diameter silicon carbide particles is D. 50 =30μm, the composition of small-diameter silicon carbide particles satisfies: w(SiC) = 99.5%; the particle size of borosilicate fine powder is D 50 =0.3μm, the borosilicate fine powder composition satisfies: w(B2O3) = 30%, w(SiO2) = 70%.

[0095] S3. Take the material W1 obtained in step S1 and paraffin wax and mix them in a mass ratio of material W1: paraffin wax = 100: 6 for the third time. Put the material W1 and paraffin wax into a kneader and heat and mix them. The mixing temperature is 120℃ and the time is 4h to obtain material W3.

[0096] S4. Take the material W2 obtained in step S1 and paraffin wax and mix them in a mass ratio of material W2: paraffin wax = 100: 6 for the fourth time. Put material W2 and paraffin wax into a kneader and heat and mix them at a constant temperature of 120℃ for 4 hours to obtain material W4.

[0097] S5. Take material W3 and place it in a gyratory granulator. After granulation through an 80-mesh sieve, material W5 is obtained. Take material W4 and place it in a gyratory granulator. After granulation through an 80-mesh sieve, material W6 is obtained.

[0098] S6. Take materials W5 and W6 from step S4, place them in a dry pressing mold, and then dry press to obtain a preform P0. The material placement process is as follows: the material placement sequence is bottom → middle → top, stacking materials of large-small-large particle size in sequence. That is, first lay a layer of material W5 in the mold as the lower layer of the sandwich structure, then lay a layer of material W6 as the middle layer of the sandwich structure, and then lay a layer of material W5 as the upper layer of the sandwich structure. Each layer of material is smoothed with a scraper. The mass ratio of the upper layer, middle layer and lower layer is 11:8:11. The axial pressure during dry pressing is 5MPa, and the holding time is 15s to obtain the preform P0.

[0099] S7. Place the preform P0 obtained in step S6 into a resistance furnace for sintering, and program the temperature to the target temperature to obtain a porous ceramic preform P1 with a "sandwich" structure; wherein the specific heating process during sintering includes:

[0100] The process involves heating from 0℃ to 200℃ in 2 hours; heating from 200℃ to 400℃ in 2 hours; holding at 400℃ for 3 hours; heating from 400℃ to 600℃ in 3 hours; holding at 600℃ for 5 hours; and heating from 600℃ to the sintering temperature of 1150℃ in 2.5 hours, followed by holding at 1150℃ for 35 minutes.

[0101] S8. Place the porous ceramic preform P1 with a "sandwich" structure obtained in step S7 into a nitrogen atmosphere vacuum pressure impregnation furnace, and program it to the target parameters to obtain an aluminum silicon carbide-based composite material preform P2. Specifically, the vacuum degree in the nitrogen atmosphere vacuum pressure impregnation furnace is -90 Pa, the temperature of the ZL101 aluminum alloy liquid is 710℃, the purity of nitrogen is ≥99.999%, the purity of magnesium is ≥99.99%, the amount of magnesium added is 0.7% of the mass of ZL101 aluminum alloy, the temperature of the ZL101 aluminum alloy liquid when magnesium is added is 685℃, the impregnation pressure is 3 MPa, and the holding time is 20 min to obtain the aluminum silicon carbide-based composite material preform P2.

[0102] S9. After the aluminum silicon carbide-based composite material preform P2 obtained in step S8 is subjected to machining processes such as wire cutting, milling, and grinding, the surface is sandblasted with 300-mesh white corundum sand to obtain aluminum silicon carbide-based product P3.

[0103] The aluminum-silicon carbide composite material obtained in this embodiment has a thickness of 30 mm and a sandwich structure. The physicochemical parameters meet the following requirements: the volume percentage of silicon carbide-based porous ceramic preform to aluminum alloy is 70:30; the porosity of silicon carbide-based porous ceramic preform is 30%; and the three-point bending strength of silicon carbide-based porous ceramic is 9 MPa.

[0104] The aluminum-silicon carbide composite material has a volume fraction of 99.8% and a density of less than 3.04 g / cm³. 3 The three-point bending strength is 380MPa, the thermal conductivity is 210W / m·K, and the coefficient of thermal expansion is 7ppm / ℃.

[0105] The metallographic structure of the aluminum silicon carbide composite material prepared in this embodiment is shown in the figure below. Figure 2 As shown, the silicon carbide particles and pores in the upper and lower layers are relatively large, while those in the middle layer are relatively small, forming an internal capillary structure with "upper layer → middle layer" and "lower layer → middle layer". There are no transition layers between the upper / middle layer and the lower / middle layer. The molten aluminum alloy in the upper, middle, and lower layers is completely infiltrated into the silicon carbide ceramic preform, tightly coating the surface of the silicon carbide particles and being uniformly distributed without defects such as cracks or shrinkage cavities.

[0106] As can be seen from the above solution, the present invention solves the problem that aluminum liquid cannot penetrate the thick silicon carbide ceramics and the physical and chemical properties of the finished product are low when using low-pressure vacuum impregnation.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an aluminum-silicon carbide composite material, characterized in that, The process includes the following: Borosilicate fine powder is mixed with large-particle-size silicon carbide particles to obtain a large-particle-size mixture W1; borosilicate fine powder is mixed with small-particle-size silicon carbide particles to obtain a small-particle-size mixture W2; the particle size of the large-particle-size silicon carbide particles is larger than the particle size of the small-particle-size silicon carbide particles; wherein, the composition of the borosilicate fine powder satisfies: 25% ≤ w (B2O3)≤30%, 70%≤ w (SiO2)≤75%; Large-particle-size mixture W1 is mixed with paraffin wax to obtain material W3; small-particle-size mixture W2 is mixed with paraffin wax to obtain material W4. The material W3 is granulated to obtain material W5; the material W4 is granulated to obtain material W6. Using the materials W5 and W6, a sandwich structure is laid out, and the sandwich structure is dry-pressed to obtain a sandwich structure blank P0; wherein, when laying the materials, the middle layer of the sandwich structure is laid out with material W6, and the upper and lower layers of the sandwich structure are laid out with material W5. The green body P0 is sintered to obtain a preform P1 of silicon carbide-based porous ceramic with a sandwich structure; The preform P1 is impregnated with aluminum alloy to obtain the aluminum silicon carbide composite material; When impregnating the preform P1 with aluminum alloy, a quenched and tempered aluminum alloy is used, and the impregnation process specifically includes: Place the preform P1 in the mold and preheat it together to 690-710℃; ZL101 aluminum alloy is melted. When the temperature of the ZL101 aluminum alloy melt reaches 670-690℃, magnesium is added to the ZL101 aluminum alloy melt, and then the mixture is heated together to 690-710℃ to melt the magnesium, thereby obtaining the quenched and tempered aluminum alloy. The mass of the added magnesium is 0.5wt%-0.7wt% of the mass of the ZL101 aluminum alloy melt. The preheated preform P1 and the mold are impregnated together in a protective atmosphere vacuum pressure impregnation furnace with tempered aluminum alloy. The vacuum degree of the protective atmosphere vacuum pressure impregnation furnace is -90pa, the impregnation pressure is 1.5-3MPa, and the holding time is 15-20min.

2. The method for preparing an aluminum-silicon carbide composite material according to claim 1, characterized in that: In the large particle size mixture W1, the mass ratio of silicon carbide particles to borosilicate powder is 100:(1.5-2). In the small particle size mixture W2, the mass ratio of silicon carbide particles to borosilicate powder is 100:(1.5-2). Large-diameter silicon carbide particles have a mesh size of 100-200 mesh and an 80μm diameter. <D 50 <100μm; Small-diameter silicon carbide particles have a mesh size of 400-600 mesh and a diameter of 30 μm. <D 50 <40μm; The compositions of large-diameter and small-diameter silicon carbide particles satisfy the following: w (SiC)≥98%; The particle size of the borosilicate powder is 0.3 μm. <D 50 <0.8μm.

3. The method for preparing an aluminum-silicon carbide composite material according to claim 1, characterized in that: When large particle size mixture W1 is mixed with paraffin to obtain material W3, the mass ratio of material W1 to paraffin is 100:(6-10), the temperature is 110-120℃, and the time is 2-4h. When small particle size mixture W2 is mixed with paraffin to obtain material W4, the mass ratio of material W2 to paraffin is 100:(6-10), the temperature is 110-120℃, and the time is 2-4h.

4. The method for preparing an aluminum-silicon carbide composite material according to claim 1, characterized in that: Material W5 has a mesh size of 80 mesh or less, and material W6 has a mesh size of 80 mesh or less.

5. The method for preparing an aluminum-silicon carbide composite material according to claim 1, characterized in that, When using materials W5 and W6 to lay the sandwich structure, the thickness ratio of the upper layer, the middle layer and the lower layer is (7-11):(6-8):(7-11). When using materials W5 and W6 to lay the sandwich structure, first lay the lower layer with material W5 in the mold, and after leveling the lower layer, lay the middle layer with material W6 on top of the lower layer, and after leveling the middle layer, lay the upper layer with material W5 on top of the middle layer, and after leveling the upper layer, to obtain the sandwich structure.

6. The method for preparing an aluminum-silicon carbide composite material according to claim 1, characterized in that, When dry pressing the sandwich structure, the axial pressure is 2-5 MPa and the holding time is 5-15 s.

7. The method for preparing an aluminum-silicon carbide composite material according to claim 1, characterized in that, When sintering the blank P0, the sintering temperature is 1050-1150℃ and the sintering time is 20min-35min; The specific heating process during sintering includes: The heating process takes 2-3 hours to raise the temperature from 0℃ to 200℃; 2-4 hours to raise the temperature from 200℃ to 400℃; 3-6 hours to hold at 400℃; 2-3 hours to raise the temperature from 400℃ to 600℃; 4-5 hours to hold at 600℃; and 2-2.5 hours to raise the temperature from 600℃ to the sintering temperature.

8. An aluminum-silicon carbide composite material, characterized in that, The aluminum silicon carbide composite material is prepared by the preparation method according to any one of claims 1-7.

9. The aluminum-silicon carbide composite material according to claim 8, characterized in that, The physicochemical parameters of the aluminum silicon carbide composite material are as follows: The volume percentage of silicon carbide-based porous ceramic preform to aluminum alloy in aluminum-silicon carbide composite material is (50~70):(30~50), the porosity of silicon carbide-based porous ceramic preform is 30%~50%, and the three-point bending strength of silicon carbide-based porous ceramic is greater than 6MPa. The aluminum-silicon carbide composite material has a volume fraction greater than 99.5% and a density less than 3.5 g / cm³. 3 The three-point bending strength is 340~380MPa, the thermal conductivity is greater than 195W / m·K, and the coefficient of thermal expansion is less than 7.5ppm / ℃; The thickness of the aluminum silicon carbide composite material is 20-30 mm.

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