Aluminum-based silicon carbide, method for preparing the same, heat sink, and device

Abstract

Embodiments of the present application provide an aluminum-based silicon carbide, a preparation method thereof, a heat dissipation member and equipment. The aluminum-based silicon carbide comprises mixed aluminum alloy particles and beta-silicon carbide particles. The beta-silicon carbide particles comprise first beta-silicon carbide particles with a D50 of 2-4 mu m and second beta-silicon carbide particles with a D50 of 6-12 mu m. The volume fraction of the first beta-silicon carbide particles in the beta-silicon carbide is 20-45%, and the volume fraction of the second beta-silicon carbide in the beta-silicon carbide is 55-80%. The beta-silicon carbide particles are spherical particles, and the sphericity of the spherical particles is greater than or equal to 0.80. The present application improves the plasticity of the obtained aluminum-based silicon carbide by adding spherical beta-silicon carbide particles with different D50 particle size ratios in the aluminum alloy.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of powder metallurgy, and particularly relates to an aluminum-based silicon carbide, a preparation method thereof, a heat dissipation piece and equipment. BACKGROUND

[0002] As a heat dissipation device, the VC heat plate can continuously evaporate and condense liquid working medium to realize heat dissipation of equipment. The evaporation and condensation efficiency of the liquid working medium mainly depends on the thermal conductivity of the plate materials on both sides of the VC heat plate. Therefore, in order to further improve the heat dissipation effect of the VC heat plate, a material with high thermal conductivity can be selected to prepare the VC heat plate.

[0003] The aluminum-based silicon carbide is a composite material prepared by taking an aluminum alloy as a matrix and silicon carbide as a reinforcing phase. The aluminum-based silicon carbide has advantages of high strength, high thermal conductivity and low thermal expansion coefficient, and is a better choice for preparing the VC heat plate.

[0004] However, the existing aluminum-based silicon carbide has the problem of low plasticity, which limits its application.

[0005] Therefore, it is urgent to develop an aluminum-based silicon carbide with high plasticity to provide more choices for the field of heat-conducting materials. SUMMARY

[0006] The embodiments of the present application provide an aluminum-based silicon carbide, a preparation method thereof, a heat dissipation piece and equipment, so as to improve the plasticity of the aluminum-based silicon carbide.

[0007] In a first aspect, the embodiments of the present application provide an aluminum-based silicon carbide, comprising: mixed aluminum alloy particles and beta-silicon carbide particles.

[0008] The beta-silicon carbide particles comprise first beta-silicon carbide particles with a D50 of 2-4 mu m and second beta-silicon carbide particles with a D50 of 6-12 mu m.

[0009] The volume fraction of the first beta-silicon carbide particles in the beta-silicon carbide is 20-45%, and the volume fraction of the second beta-silicon carbide in the beta-silicon carbide is 55-80%.

[0010] The beta-silicon carbide particles are spherical particles, and the sphericity of the spherical particles is greater than or equal to 0.80.

[0011] In a possible implementation, the volume fraction of the beta-silicon carbide particles in the aluminum-based silicon carbide is 5-15%.

[0012] In a possible implementation, the aluminum alloy particles comprise at least one of 6061 aluminum alloy particles and 6063 aluminum alloy particles.

[0013] And / or, the D50 of the aluminum alloy particles is 5-20 μm.

[0014] In a second aspect, the embodiments of the present application provide a preparation method of the above-mentioned aluminum-based silicon carbide, comprising:

[0015] pressing a mixture comprising an aluminum alloy precursor and β-silicon carbide particles to obtain a green body;

[0016] sintering the green body to obtain a sintered body;

[0017] extruding the sintered body to obtain an extruded body;

[0018] post-processing the extruded body to obtain the aluminum-based silicon carbide.

[0019] In a possible implementation, the aluminum alloy precursor comprises at least one of aluminum, aluminum-silicon alloy, and aluminum-magnesium alloy.

[0020] And / or, the particle size of the aluminum is 5-20 μm.

[0021] And / or, the particle size of the aluminum-silicon alloy is 10-20 μm.

[0022] And / or, the particle size of the aluminum-magnesium alloy is 10-20 μm.

[0023] And / or, the relative density of the green body is 85%-95%.

[0024] And / or, the density of the extruded body is 2.76 g / cm 3 -2.82 g / cm 3 .

[0025] In a possible implementation, the pressing comprises cold isostatic pressing, and the cold isostatic pressing comprises:

[0026] holding the green body at 200-300 MPa for 60-120 s;

[0027] And / or, before the sintering, the method further comprises a pure aluminum sheath and vacuum degassing.

[0028] The vacuum degassing comprises:

[0029] heating the green body to 400-500 ℃, and holding the green body at a vacuum degree less than or equal to 1×10 -3 Pa for 1-10 h;

[0030] And / or, the sintering comprises atmospheric sintering, and the atmospheric sintering comprises:

[0031] The green body is heated to 580-630℃ at a heating rate of 5-10℃ / min, and sintered for 6-10h.

[0032] In a possible implementation, the extrusion comprises:

[0033] First extrusion: the sintered body is extruded at an extrusion ratio (4-8):1 to obtain an extruded intermediate;

[0034] Second extrusion: the extruded intermediate is extruded at an extrusion ratio (10-25):1 to obtain an extruded body;

[0035] In the first extrusion, the temperature of the sintered body is 480-520℃, and the extrusion speed is 2-5mm / s;

[0036] In the second extrusion, the temperature of the extruded intermediate is 450-480℃;

[0037] The first extrusion and the second extrusion further comprise water mist cooling, and the cooling rate of the water mist cooling is greater than or equal to 50℃ / s.

[0038] In a possible implementation, the post-processing comprises water quenching and aging treatment;

[0039] In the water quenching, the temperature of the extruded body is 500-560℃, and the water quenching time is 20-30min;

[0040] The aging treatment is performed at a temperature of 170-180℃ for 7-9h.

[0041] In a third aspect, the embodiments of the present application provide a heat dissipation piece, comprising the aluminum-based silicon carbide or the aluminum-based silicon carbide prepared by the above preparation method.

[0042] In a fourth aspect, the embodiments of the present application provide a device, comprising the aluminum-based silicon carbide or the aluminum-based silicon carbide prepared by the above preparation method or the heat dissipation piece.

[0043] The aluminum-based silicon carbide and the preparation method, the heat dissipation piece and the device provided by the embodiments of the present application can improve the uniformity and the compactness of the aluminum-based silicon carbide, reduce the internal stress between the beta-silicon carbide and the aluminum alloy, optimize the thermal conductivity of the aluminum-based silicon carbide, and enhance the plasticity of the aluminum-based silicon carbide, by adjusting the volume fraction of the first beta-silicon carbide particles with D50=2-4μm to be 25-45%, the volume fraction of the second beta-silicon carbide particles with D50=6-12μm to be 55-85%, and making the sphericity of the beta-silicon carbide particles greater than or equal to 0.80. DETAILED DESCRIPTION

[0044] The exemplary embodiments will be described in detail below with reference to the attached drawings. The embodiments described in the following exemplary embodiments do not represent all the technical solutions consistent with the present application. Instead, they are only examples of devices and methods consistent with some aspects of the present application, as detailed in the appended claims.

[0045] In the prior art, when preparing aluminum-based silicon carbide, the silicon carbide particles are prone to agglomeration, resulting in uneven internal organization of the aluminum-based silicon carbide, which can significantly reduce the mechanical and thermal physical properties of the aluminum-based silicon carbide.

[0046] The aluminum-based silicon carbide and the preparation method thereof provided by the present application solve the technical problems of low plasticity and poor thermal conductivity caused by uneven mixing of β-silicon carbide in the aluminum alloy matrix by using the technical means of preparing aluminum-based silicon carbide by using double-particle-size-graded β-silicon carbide.

[0047] The technical solutions of the present application and how the technical solutions of the present application solve the above technical problems will be described in detail below with specific examples. The following specific examples can be combined with each other, and the same or similar concepts or processes can not be described again in some examples.

[0048] The present application provides an aluminum-based silicon carbide, comprising: mixed aluminum alloy particles and β-silicon carbide particles;

[0049] The β-silicon carbide particles comprise first β-silicon carbide particles with a D50 of 2-4 μm and second β-silicon carbide particles with a D50 of 6-12 μm;

[0050] The volume fraction of the first β-silicon carbide particles in the β-silicon carbide is 20-45%, and the volume fraction of the second β-silicon carbide in the β-silicon carbide is 55-80%;

[0051] The β-silicon carbide particles are spherical particles, and the sphericity of the spherical particles is greater than or equal to 0.80.

[0052] The present application uses β-silicon carbide particles including first β-silicon carbide particles with D50 of 2-4 μm and second β-silicon carbide particles with D50 of 6-12 μm to prepare aluminum-based silicon carbide, wherein the first β-silicon carbide particles with D50 of 2-4 μm as fine particle components with smaller particle size can fill the gaps of the second β-silicon carbide particles with D50 of 6-12 μm, improve the internal compactness of the aluminum-based silicon carbide, and reduce stress concentration and crack generation. Moreover, the second β-silicon carbide particles with D50 of 6-12 μm can span across both sides of the crack, hinder crack opening through interface shear force, and bear the main load to improve the rigidity and strength of the aluminum-based silicon carbide; the first β-silicon carbide particles with D50 of 2-4 μm can densely distribute at the front end of the crack, like a "nail" to hinder the forward advancement of the crack tip, significantly improve the crack propagation resistance, constrain the dislocation movement of the matrix, and improve the strength of the aluminum-based silicon carbide. By selecting β-silicon carbide with sphericity greater than or equal to 0.80, the stress concentration source can be eliminated, the generation of cracks can be blocked, and the flowability and compactness of the material melt can be improved. Moreover, the spherical β-silicon carbide has no preferred orientation during preparation, has high size stability, and can improve the isotropy of the mechanical properties of the aluminum-based silicon carbide. Finally, the toughness of the obtained aluminum-based silicon carbide is greatly improved.

[0053] By selecting the volume ratio of the first β-silicon carbide particles with D50 of 2-4 μm to be 20%-45% and the volume ratio of the second β-silicon carbide particles with D50 of 6-12 μm to be 55%-80%, the filling degree of the first β-silicon carbide particles to the second β-silicon carbide particles can be ensured to be sufficient to improve the compactness of the aluminum-based silicon carbide, and meanwhile, the dual grading state of the particle size of the β-silicon carbide particles in the aluminum-based silicon carbide can be ensured to achieve the ideal toughness improvement effect.

[0054] Exemplarily, the D50 of the first β-silicon carbide particles can be 2 μm, 3 μm, 4 μm, or a range formed by any two of them.

[0055] Exemplarily, the D50 of the second β-silicon carbide particles can be 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, or a range formed by any two of them.

[0056] Exemplarily, the volume fraction of the first β-silicon carbide particles in the β-silicon carbide particles can be 20%, 25%, 30%, 35%, 40%, 45%, or a range formed by any two of them.

[0057] Exemplarily, the volume fraction of the second β-silicon carbide particles in the β-silicon carbide particles can be 55%, 60%, 65%, 70%, 75%, 80%, or a range formed by any two of them.

[0058] In some other optional embodiments, the β-silicon carbide particles can also include particles with a D50 of 1.5 μm and particles with a D50 greater than 12 μm and less than or equal to 15 μm to perfect the interstices between the particles in the aluminum-based silicon carbide and further improve the compactness of the aluminum-based silicon carbide.

[0059] In some specific embodiments, the volume fraction of the β-silicon carbide particles in the aluminum-based silicon carbide is 5%-15%.

[0060] By selecting the volume fraction of the β-silicon carbide particles in the aluminum-based silicon carbide to be 5%-15%, the continuous plastic deformation capacity of the aluminum alloy matrix caused by the β-silicon carbide particles being divided into isolated parts can be avoided, and the phenomenon of straight-line crack penetration of the material caused by the agglomeration of the β-silicon carbide particles can also be avoided, thereby obtaining an aluminum-based silicon carbide with stronger plastic deformation capacity. Moreover, within this volume fraction range, the porosity of the obtained aluminum-based silicon carbide is good, the thermal conductivity of the aluminum-based silicon carbide can be further optimized, and the thermal expansion coefficient will not be excessively reduced.

[0061] Illustratively, the volume fraction of the β-silicon carbide particles in the aluminum-based silicon carbide can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, or a range formed by any two of them.

[0062] In some specific embodiments, the aluminum alloy particles include at least one of 6061-series aluminum alloy particles and 6063-series aluminum alloy particles.

[0063] 6061-series aluminum alloy and 6063-series aluminum alloy both contain Si and Mg elements, wherein the presence of Si can preferentially react with C to form a thermodynamically stable phase Al4SiC4, instead of easily hydrolyzed Al4C3, thereby improving the interface stability of the aluminum-based silicon carbide from the source. Mg can selectively adsorb and react on the surface of β-silicon carbide, removing the oxide layer on its surface, so that aluminum and β-silicon carbide are in direct contact and have better mixing. More importantly, 6061-series aluminum alloy and 6063-series aluminum alloy belong to precipitation strengthening type aluminum alloy, and after solid solution and artificial aging treatment, nanoscale β''-Mg2Si phase with a size much smaller than that of the β-silicon carbide particles can be precipitated, forming a double-scale reinforcement: β-silicon carbide particles bear the main load, improve the stiffness of the aluminum-based silicon carbide, and nanoscale precipitated phase β''-Mg2Si phase pins dislocations, improves the strength of the aluminum-based silicon carbide, and the 6061-series aluminum alloy and 6063-series aluminum alloy matrix retains the plastic deformation capacity, thereby improving the toughness of the aluminum-based silicon carbide. Therefore, using 6061-series aluminum alloy and 6063-series aluminum alloy as the matrix can obtain an aluminum-based silicon carbide with higher mechanical strength.

[0064] In some specific embodiments, the D50 of the aluminum alloy particles is 5 μm-20 μm.

[0065] When the particle size of the aluminum alloy particles is much larger than the particle size of the β-silicon carbide particles, the β-silicon carbide particles will be "submerged" in the larger aluminum alloy grains, forming an "island effect" and losing load transfer capability. When the particle size of the aluminum alloy particles is much smaller than the particle size of the β-silicon carbide particles, the fine aluminum alloy grains cannot effectively wrap the large β-silicon carbide particles, resulting in weakening of the interfacial bonding force. In order to ensure that the dislocation movement inside the aluminum-based silicon carbide is not hindered, and to obtain aluminum-based silicon carbide with stronger plasticity, aluminum alloy particles with D50 of 5 μm-20 μm can be selected.

[0066] Exemplarily, the D50 of the aluminum alloy particles can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or a range formed by any two of them.

[0067] The aluminum-based silicon carbide provided by the embodiments of the present application is prepared by including β-silicon carbide particles with D50=2 μm-4 μm and D50=6 μm-12 μm, which improves the compactness of the aluminum-based silicon carbide, reduces the internal stress between the β-silicon carbide and the aluminum alloy, and achieves the technical effect of enhancing the plasticity of the aluminum-based silicon carbide.

[0068] The present application also provides a preparation method of the above-mentioned aluminum-based silicon carbide, which comprises:

[0069] pressing a mixture comprising an aluminum alloy precursor and β-silicon carbide particles to obtain a green body;

[0070] sintering the green body to obtain a sintered body;

[0071] extruding the sintered body to obtain an extruded body;

[0072] post-treating the extruded body to obtain the aluminum-based silicon carbide.

[0073] In some specific embodiments, the aluminum alloy precursor comprises at least one of aluminum, aluminum-silicon alloy, and aluminum-magnesium alloy.

[0074] In the preparation of raw materials, the aluminum alloy precursor can be pure aluminum, can include aluminum alloys of multiple elements, and can also be binary alloys of aluminum and other elements. Because Si can effectively reduce the surface tension of the aluminum melt and significantly improve the wettability of the aluminum melt to the β-silicon carbide particles. Mg is also an effective wetting promoter that can react with the oxide film (Al2O3) on the surface of the melt or the surface of the β-silicon carbide particles to form MgO or MgAl2O4, thereby destroying the oxide layer that hinders wetting and also reducing the surface tension of the melt. However, aluminum alloys that include multiple elements have complex compositions, in addition to the main alloying elements, they also contain multiple trace elements. These elements can not help improve wettability, or even interfere with the wetting promotion of Si or Mg, or bring other negative effects (such as the formation of harmful phases). Therefore, in order to obtain aluminum-based silicon carbide with better performance, the present application selects aluminum, aluminum-silicon alloy, aluminum-magnesium alloy, etc. with simple element composition and high purity to prepare aluminum-based silicon carbide. Specifically, the aluminum-silicon alloy can be an Al-20Si alloy, and the aluminum-magnesium alloy can be an Al-20Mg alloy. It should be noted that according to actual needs, single elements or alloys of the element and aluminum with the addition of other elements, such as copper, etc. can also be selected as raw materials, which are not limited further herein.

[0075] In some specific embodiments, the particle size of the aluminum as the aluminum alloy precursor is 5 μm-20 μm.

[0076] Since the density of β-silicon carbide is higher than the density of aluminum, the aluminum with a particle size of 5 μm-20 μm is mixed with the above-mentioned double-particle-size graded β-silicon carbide. On the one hand, it can achieve more uniform mixing and improve the density of the aluminum-based silicon carbide. On the other hand, by selecting the particle size to control the specific surface area of the aluminum, the interfacial reaction kinetics during mixing can be controlled, the generation of harmful phases can be reduced, and aluminum-based silicon carbide with more excellent performance can be obtained.

[0077] Illustratively, the particle size of the aluminum can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or a range formed by any two of them.

[0078] In some specific embodiments, the particle size of the aluminum-silicon alloy is 10 μm-20 μm.

[0079] The diffusion of Si elements in the aluminum-silicon alloy is slow, and by controlling the particle size of the aluminum-silicon alloy used, the silicon segregation phenomenon can be avoided and the formation of Al4C3 can be inhibited.

[0080] Exemplarily, the particle size of the aluminum-silicon alloy can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or a range defined by any two of them.

[0081] In some specific embodiments, the particle size of the aluminum-magnesium alloy is 10 μm-20 μm.

[0082] The Mg element in the aluminum-magnesium alloy can promote interface wetting but is easy to oxidize, and therefore, the particle size of the aluminum-magnesium alloy needs to be controlled to reduce the possibility of oxidation.

[0083] Exemplarily, the particle size of the aluminum-magnesium alloy can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm, or a range defined by any two of them.

[0084] The present application balances the complex interaction between the reinforcing phase and the matrix at the microscale by regulating the particle size of the aluminum alloy precursor used in combination with the β-silicon carbide with a double particle size gradation, and obtains an aluminum-based silicon carbide with better performance.

[0085] In some specific embodiments, the green body obtained by pressing the mixture comprising the aluminum alloy precursor and the β-silicon carbide particles has a relative density of 85%-95%.

[0086] The relative density of the green body represents the strength of the binding force between the particles in the green body. By pressing the green body to have a relative density of 85%-95%, it is ensured that there are connected pore channels needed for sintering in the green body, so that the gas generated in the green body during sintering can be timely discharged, and a sintered body with better density is obtained, and the sintering process will not cause excessive deformation and cracking.

[0087] Exemplarily, the relative density of the green body can be 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, or a range defined by any two of them.

[0088] In some specific embodiments, the density of the extruded body is 2.76 g / cm 3 -2.82 g / cm 3 .

[0089] The density of the aluminum-based silicon carbide reflects the size of the porosity, and affects the strength, rigidity, thermal conductivity, toughness and other properties. In order to ensure that the aluminum-based silicon carbide has sufficient strength, the specific strength, specific rigidity, thermal conductivity and toughness need to be maximized by controlling the density. During the preparation process, the density of the green body will change sharply after sintering and extrusion, and the density of the extruded body will change to a negligible extent after post-processing. Therefore, the density of the aluminum-based silicon carbide can be obtained by controlling the density of the extruded body. Through the experiments of the inventor, when the density of the extruded body after sintering and extrusion is 2.76g / cm 3 -2.82g / cm 3 , the aluminum-based silicon carbide with higher strength, better toughness and better thermal conductivity can be obtained.

[0090] Exemplarily, the density of the extruded body can be 2.76g / cm 3 , 2.77g / cm 3 , 2.78g / cm 3 , 2.79g / cm 3 , 2.80g / cm 3 , 2.81g / cm 3 , 2.82g / cm 3 , or a range consisting of any two of them.

[0091] In some specific embodiments, the pressing includes cold isostatic pressing; the cold isostatic pressing includes: placing the green body under a pressure of 200MPa-300MPa for 60s-120s.

[0092] By selecting cold isostatic pressing to obtain the green body, the relative density difference of each part of the green body can be controlled to be less than 1%, and the density uniformity is improved. Moreover, by selecting the pressure of the cold isostatic pressing to be in the range of 200MPa-300MPa and the holding time to be in the range of 60s-120s, the delamination and layer cracking can be inhibited, the strength of the green body is improved, and a good foundation is provided for subsequent sintering and extrusion, thereby reducing problems such as sintering deformation and cracking and improving the yield. In addition, in order to avoid damage to the particle structure in the green body, density unevenness and residual stress accumulation, a pressure increasing rate less than or equal to 20MPa / min is used to reach the target pressure, and a pressure decreasing rate less than or equal to 30MPa / min is used to stabilize the volume of the green body.

[0093] Exemplarily, the pressure of the cold isostatic pressing can be 200MPa, 210MPa, 220MPa, 230MPa, 240MPa, 250MPa, 260MPa, 270MPa, 280MPa, 290MPa, 300MPa, or a range consisting of any two of them; and the holding time of the cold isostatic pressing can be 60s, 70s, 80s, 90s, 100s, 110s, 120s, or a range consisting of any two of them.

[0094] In some embodiments, the green body can be further subjected to a pure aluminum sheath and vacuum degassing before sintering.

[0095] The pure aluminum sheath refers to using pure aluminum as an outer shell to encapsulate the green body, and then vacuuming the sheath to remove oxygen, preventing the green body from being oxidized at high temperature during sintering, and inhibiting the reaction between aluminum and β-silicon carbide. Moreover, pure aluminum has strong ductility, and the plastic deformation ability of the pure aluminum sheath can make the internal green body flow uniformly, solving the dispersion problem of β-silicon carbide. Specifically, the thickness of the pure aluminum sheath is 2 mm-5 mm, and exemplarily can be 2 mm, 3 mm, 4 mm, 5 mm, or a range formed by any two of them. In some optional embodiments, the step of vacuum degassing the green body after the pure aluminum sheath includes: heating the green body to 400℃-500℃, and maintaining at a vacuum degree less than or equal to 1×10 -3 Pa for 1h-10h.

[0096] Exemplarily, the temperature of vacuum degassing can be 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, 500℃, or a range formed by any two of them; the vacuum degree can be 0.1×10 -3 Pa, 0.2×10 -3 Pa, 0.3×10 -3 Pa, 0.4×10 -3 Pa, 0.5×10 -3 Pa, 0.6×10 -3 Pa, 0.7×10 -3 Pa, 0.8×10 -3 Pa, 0.9×10 -3 Pa, 1.0×10 -3 Pa, or a range formed by any two of them.

[0097] In other embodiments, the vacuum degassing can also include stepwise heating to achieve the effect of removing moisture and organic matter, specifically, it can be: first, at room temperature, the pressure in the sheath is extracted to 5×10 -2 Pa, and heated to 100℃-160℃ for 1h to remove water vapor, then heated to 260℃-350℃ for 6h to remove organic matter, and finally, vacuumed to a pressure in the sheath less than or equal to 1.0×10 -3 Pa, and heated to 450℃ for 1h-6h to achieve further degassing.

[0098] In some embodiments, the sintering includes atmospheric sintering, and the atmospheric sintering includes: heating the green body to 580℃-630℃ at a heating rate of 5℃ / min-10℃ / min, and sintering for 6h-10h.

[0099] After the green body is sleeved and vacuumized, the inert gas protection during sintering of the green body can be omitted, and atmospheric sintering can be used to further reduce the preparation cost.

[0100] Exemplarily, the temperature of the atmospheric sintering can be 580℃, 590℃, 600℃, 610℃, 620℃, 630℃, or a range formed by any two of them; the time of the atmospheric sintering can be 6h, 7h, 8h, 9h, 10h, or a range formed by any two of them.

[0101] In some specific embodiments, the extrusion comprises: primary extrusion: the sintered body is extruded at an extrusion ratio (4-8): 1 to obtain an extruded intermediate;

[0102] Secondary extrusion: the extruded intermediate is extruded at an extrusion ratio (10-25): 1 to obtain an extruded body.

[0103] By primary extrusion of the sintered body at an extrusion ratio of (4-8): 1, not only can the preliminary mixing and densification be achieved, but also a larger plastic deformation and a more uniform stress or strain field can be provided for the sintered body, which can more effectively break the residual β-SiC agglomerates and promote the flow and redistribution of the particles in the aluminum matrix, achieving a higher level of uniform dispersion, playing a role in improving the strength and modulus and obtaining isotropic properties. Then secondary extrusion at an extrusion ratio of (10-25): 1 can provide continuous plastic deformation, so that the matrix metal can more tightly wrap the β-SiC particles, increase the mechanical interlocking, help to extrude the gas or impurities at the interface, and reduce the interface defects. More importantly, it can induce dynamic recrystallization of the aluminum matrix to generate equiaxed grains with a particle size of less than or equal to 5μm, further improving the toughness of the aluminum-based silicon carbide. Moreover, through the inventor's experiments, it is found that by extruding the sintered body twice to form a plate with a thickness of 1mm-6mm, the particles inside the plate can be aligned along the plane of the extruded body, improving the in-plane thermal conductivity of the extruded body.

[0104] Exemplarily, the extrusion ratio of the primary extrusion can be 4:1, 5:1, 6:1, 7:1, 8:1, or a range formed by any two of them; the extrusion ratio of the secondary extrusion can be 10:1, 12:1, 15:1, 17:1, 20:1, 22:1, 25:1, or a range formed by any two of them.

[0105] In some embodiments, the temperature of the sintered body during the first extrusion is 480-520°C, and the extrusion speed is 2-5 mm / s. For example, the temperature of the sintered body during the first extrusion can be 480°C, 490°C, 500°C, 510°C, 520°C, or a range defined by any two of them. The extrusion speed during the first extrusion can be 2 mm / s, 3 mm / s, 4 mm / s, 5 mm / s, or a range defined by any two of them.

[0106] In some embodiments, the temperature of the extruded intermediate during the second extrusion is 450-480°C, for example, 450°C, 460°C, 470°C, 480°C, or a range defined by any two of them. The extrusion temperature during the second extrusion can be adjusted according to the required specifications of the product, for example, 0.5-5 mm / s.

[0107] In some embodiments, water mist cooling is further included between the first extrusion and the second extrusion, and the cooling rate of the water mist cooling is greater than or equal to 50°C / s.

[0108] By performing water mist cooling after the first extrusion and maintaining a cooling rate of greater than or equal to 50°C / s, the material temperature can be quickly reduced to a temperature range in which the Al-SiC interfacial reaction is significantly slowed down or even substantially stopped, thereby maximizing the inhibition or prevention of the formation of harmful Al4C3 phase during the waiting and transportation process between the two extrusions, and effectively "freezing" the fine-grained structure formed by the first extrusion, preventing grain coarsening during this period before the second extrusion, and laying a foundation for further refining the structure in the subsequent second extrusion. In addition, by maintaining a cooling rate of greater than or equal to 50°C / s, a large number of solute atoms dissolved at high temperature have a concentration far exceeding the equilibrium solid solubility that the aluminum matrix can accommodate at room temperature after rapid cooling, obtaining a supersaturated solid solution to provide vacancies for the diffusion of strengthening phases in subsequent aging treatment.

[0109] For example, the cooling rate of the water mist cooling can be 50°C / s, 55°C / s, 60°C / s, 65°C / s, 70°C / s, 75°C / s, or a range defined by any two of them.

[0110] In some embodiments, the post-processing includes water quenching and aging treatment. During the water quenching, the temperature of the extruded body is 500-600°C, and the water quenching time is 20-30 min. The aging treatment temperature is 170-180°C, and the treatment time is 7-9 h.

[0111] The over-saturated solid solution state at high temperature is frozen by water quenching of the extruded body, thereby creating a material basis for subsequent aging strengthening. Then, the over-saturated solid solution retained by water quenching is allowed to precipitate a large number of fine and dispersed strengthening phases at a lower temperature, thereby significantly improving the strength and hardness of the material.

[0112] Exemplarily, the temperature of the extruded body during the water quenching treatment can be 500℃, 510℃, 520℃, 530℃, 540℃, 550℃, 560℃, or a range formed by any two of them; the time of the water quenching treatment can be 20min, 21min, 22min, 23min, 24min, 25min, 26min, 27min, 28min, 29min, 30min, or a range formed by any two of them.

[0113] Exemplarily, the temperature of the aging treatment can be 170℃, 171℃, 172℃, 173℃, 174℃, 175℃, 176℃, 177℃, 178℃, 179℃, 180℃, or a range formed by any two of them; the time of the aging treatment can be 7h, 8h, 9h, or a range formed by any two of them.

[0114] The preparation method provided in the embodiments of the present application enables the green body to be sintered in an atmospheric environment without element oxidation through the means of a cover and vacuum degassing, and then the sintered body is extruded twice, so that the density of the aluminum-based silicon carbide is greater than or equal to 99.5%, and the in-plane thermal conductivity of the aluminum-based silicon carbide as a plate is improved, thereby realizing synchronous improvement of toughness and thermal conductivity.

[0115] The embodiments of the present application also provide a heat dissipation piece comprising the aluminum-based silicon carbide or the aluminum-based silicon carbide prepared by the above preparation method. The heat dissipation piece has excellent toughness, use strength and thermal conductivity.

[0116] The embodiments of the present application also provide a device comprising the aluminum-based silicon carbide or the aluminum-based silicon carbide prepared by the above preparation method or the heat dissipation piece, and the device has good heat dissipation.

[0117] The technical solutions of the present application are further illustrated below by using specific examples and comparative examples.

[0118] Example 1

[0119] A β-SiC / 6061 aluminum-based silicon carbide composite material, the raw materials of which include: β-SiC particle volume fraction 14.5% (mass fraction 16.63%), Al powder (mass fraction 76.45%), Cu powder (mass fraction 0.25%), Al-20Si alloy powder (mass fraction 2.5%), and Al-20Mg alloy powder (mass fraction 4.17%).

[0120] Wherein, the purity of the β-SiC particles is ≥99.5%, the sphericity is 0.8, including first β-SiC particles with D50=2μm and second β-SiC particles with D50=6μm, the volume ratio of the first β-SiC particles to the second β-SiC particles is 3:7; the D50 of the aluminum powder is 13μm; the D50 of the copper powder is 18μm; the D50 of the Al-20Si alloy is 10μm; the D50 of the Al-20Mg alloy powder is 10μm.

[0121] The preparation method is as follows:

[0122] 1. Powder mixing: the above raw materials are put into a 50L high-speed double-motion mixer according to the volume fraction ratio, the loading ratio is 50%, and the rotation speed is 50rpm to obtain mixed powder.

[0123] 2. Cold isostatic pressing: the mixed powder is put into a φ290×455mm polyurethane soft mold and vibrated, then packaged into a cold isostatic pressing machine, the pressure of the cold isostatic pressing machine is increased to 250MPa at a pressure increasing rate of 20MPa / min, and the pressure is maintained for 90s, then the pressure is released at a pressure releasing rate of 25MPa / min, to obtain a green body with a size of φ222mm×350mm and a relative density of 92%.

[0124] 3. Vacuum degassing: the green body is sleeved with pure aluminum, the wall thickness of the pure aluminum sleeve is 2mm, the end cap is processed by a lathe and then welded by TIG (tungsten inert gas welding), the penetration depth of the weld is 2.5mm, the helium detection is qualified, then vacuum degassing is carried out, the pipe clamping is packaged after the degassing is qualified. The vacuum degassing procedure is: room temperature is extracted to 5×10 -2 Pa; 100℃×1h water vapor removal; 350℃×6h organic matter removal; vacuum degree ≤1×10 -3 Pa, 450℃×3h.

[0125] 4. Atmospheric sintering: the sleeved green body after vacuum degassing is sintered at 625℃ for 4h to obtain a sintered body with a relative density of 95%.

[0126] 5. Extrusion: one-time extrusion: the one-time extrusion is carried out by using a 1800T horizontal extruder, the extrusion ratio is 4:1, the 500℃ sintered body is put into a 450℃ mold, the ϕ230mm extrusion cylinder at 420℃ is used, and the one-time extrusion is carried out at an extrusion speed of 2.5mm / s to obtain a ϕ115mm round bar;

[0127] The obtained round bar is subjected to online water mist cooling at a cooling rate of 50-100℃ / s;

[0128] Secondary extrusion: after slitting the car body, the round bar at 475℃ is subjected to secondary extrusion with an extrusion ratio of 25:1 and an extrusion speed of 4.5 mm / s, to obtain an extruded body with a width of 100 mm and a thickness of 2 mm, and the density of the extruded body is 2.80 g / cm³.

[0129] 6. Post-processing: the extruded body is rolled to a thickness of 0.1 mm, the edge crack is <10 mm, and the extruded body is subjected to water quenching at 520℃ for 0.4 h, aging treatment at 175℃ for 8 h, and air cooling, to obtain β-SiC / 6061 aluminum-based silicon carbide.

[0130] Performance: yield strength 320 MPa, elongation 12.2%, thermal conductivity 192 W / (m•K), and elastic modulus 95 GPa.

[0131] Example 2

[0132] A β-SiC / 6063 aluminum-based silicon carbide, the raw materials comprising: β-SiC particles with a volume fraction of 12.5% (mass fraction 14.39%), aluminum powder (mass fraction 80.48%), Al-20Si alloy powder (mass fraction 1.71%), and Al-20Mg alloy powder (mass fraction 3.42%).

[0133] The purity of the β-SiC particles is ≥99.5%, the sphericity is 0.8, and the β-SiC particles include first β-SiC particles with a D50 of 2 μm and second β-SiC particles with a D50 of 6 μm, and the volume ratio of the first β-SiC particles to the second β-SiC particles is 4:6; the D50 of the aluminum powder is 10 μm; the D50 of the Al-20Si alloy is 10 μm; and the D50 of the Al-20Mg alloy powder is 10 μm.

[0134] The preparation method is the same as that of Example 1.

[0135] Example 3

[0136] A β-SiC / 6061 aluminum-based silicon carbide composite material, the raw materials comprising: β-SiC particles with a volume fraction of 15.0% (mass fraction 17.19%), aluminum powder (mass fraction 75.94%), copper powder (mass fraction 0.25%), Al-20Si alloy powder (mass fraction 2.48%), and Al-20Mg alloy powder (mass fraction 4.14%).

[0137] Wherein, the purity of the β-SiC particles is ≥99.5%, the sphericity is 0.8, including first β-SiC particles with D50=2.5 μm and second β-SiC particles with D50=10 μm, the volume ratio of the first β-SiC particles to the second β-SiC particles is 2:8; the D50 of the aluminum powder is 13 μm; the D50 of the copper powder is 20 μm; the D50 of the Al-20Si alloy is 15 μm; the D50 of the Al-20Mg alloy powder is 15 μm.

[0138] The preparation process is the same as that of Example 1.

[0139] Example 4

[0140] A β-SiC / 6061 aluminum-based silicon carbide, the rest of the raw materials and the preparation method are the same as those of Example 1, except that the D50 of the first β-SiC particles is 4 μm and the D50 of the second β-SiC particles is 12 μm.

[0141] Example 5

[0142] A β-SiC / 6061 aluminum-based silicon carbide, the rest of the raw materials and the preparation method are the same as those of Example 1, except that the volume fraction of the β-SiC particles is 5%.

[0143] Example 6

[0144] A β-SiC / 6061 aluminum-based silicon carbide, the rest of the raw materials and the preparation method are the same as those of Example 1, except that the volume fraction of the β-SiC particles is 4%.

[0145] Example 7

[0146] A β-SiC / 6061 aluminum-based silicon carbide, the rest of the raw materials and the preparation method are the same as those of Example 1, except that the volume fraction of the β-SiC particles is 10%.

[0147] Example 8

[0148] A β-SiC / 6061 aluminum-based silicon carbide, the rest of the raw materials and the preparation method are the same as those of Example 1, except that the volume fraction of the β-SiC particles is 16%.

[0149] Comparative Example 1

[0150] A β-SiC / 6061 aluminum-based silicon carbide, the rest of the raw materials and the preparation method are the same as those of Example 1, except that the volume ratio of the first β-SiC particles with D50=2 μm to the second β-SiC particles with D50=6 μm is 1:1.

[0151] Comparative Example 2

[0152] A β-SiC / 6061 aluminum matrix silicon carbide, the rest of the raw materials and the preparation method are the same as example 1, except that the volume ratio of the first β-SiC particles with D50=2μm and the second β-SiC particles with D50=6μm is 1:9.

[0153] Comparative example 3

[0154] A β-SiC / 6061 aluminum matrix silicon carbide, the rest of the raw materials and the preparation method are the same as example 1, except that the D50 of the first β-SiC particles is 5μm and the D50 of the second β-SiC particles is 13μm.

[0155] Comparative example 4

[0156] A β-SiC / 6061 aluminum matrix silicon carbide, the rest of the raw materials and the preparation method are the same as example 1, except that the D50 of the first β-SiC particles is 1μm and the D50 of the second β-SiC particles is 5μm.

[0157] Comparative example 5

[0158] An α-SiC / 6061 aluminum matrix silicon carbide, the rest of the raw materials and the preparation method are the same as example 3, except that α-SiC particles with D50=10μm are used instead of β-SiC particles.

[0159] Comparative example 6

[0160] A β-SiC / 6061 aluminum matrix silicon carbide, the rest of the raw materials and the preparation method are the same as example 1, except that the D50 of the β-SiC particles is 6μm, there is no double particle size grading, and the total addition volume fraction is 12.5%.

[0161] Comparative example 7

[0162] A β-SiC / 6061 aluminum matrix silicon carbide, the rest of the raw materials and the preparation method are the same as example 1, and the sphericity of the spherical particles is 0.5.

[0163] The materials obtained in examples 1-8 and comparative examples 1-7 above were tested for the following properties:

[0164] Density: tested according to the provisions of GB / T3850-2015;

[0165] Yield strength: sample size was prepared according to GB / T16865, and then tested according to the test method in GB / T228.2021;

[0166] Elongation: sample size was prepared according to GB / T16865, and then tested according to the test method in GB / T228.2021;

[0167] Elastic modulus: tested according to the provisions of GB / T22315-2008;

[0168] Thermal conductivity: tested according to the provisions of GB / T22588-2008;

[0169] Edge crack length: the extrusion body is rolled to a thickness of 0.1 mm, the edge crack is observed, and the edge crack length of a side of the extrusion body is tested.

[0170] The test results are shown in Table 1:

[0171] Table 1

[0172]

[0173] As can be seen from the results in Table 1, the aluminum-based silicon carbide provided by the application has excellent plasticity, toughness and thermal conductivity, and when used for preparing VC vapor chamber, its thermal conductivity is better than that of stainless steel / aluminum composite material; and its density is lower, which can reduce the use weight to 32% of copper, and it is an excellent VC vapor chamber material.

[0174] The aluminum-based silicon carbide material obtained in Examples 1-8 has a yield strength of not less than 290 MPa, an elongation of not less than 8.9%, an elastic modulus of not less than 80 GPa, a thermal conductivity of not less than 170 W / (m•K), and a single-edge crack length of not more than 12 mm.

[0175] Compared with Comparative Examples 1 and 2, the aluminum-based silicon carbide obtained in Example 1 has better yield strength, elongation and thermal conductivity, and smaller single-edge crack length. This shows that when the volume fraction of the first β-SiC particles with smaller particle size is in the range of 20%-45% and the volume fraction of the second β-SiC particles with smaller particle size is in the range of 55%-80%, the plasticity and thermal conductivity of the obtained aluminum-based silicon carbide are better. Analyzing the reason, when the volume fraction of the first β-SiC particles with smaller particle size is larger, the particle size of the β-SiC particles in the system is close to a single fine particle size, the particle spacing is small, and the crack is easy to expand; when the volume fraction of the second β-SiC particles with larger particle size is larger, the particle spacing is larger, the small particles are insufficient, which leads to insufficient material density, and finally the plasticity and thermal conductivity of the aluminum-based silicon carbide are poor.

[0176] Compared with Comparative Example 3 and Comparative Example 4, the aluminum-based silicon carbide obtained in Example 1 has higher yield strength, elongation, elastic modulus and thermal conductivity, and smaller single-side edge crack length, which shows that when the D50 particle size of the first β-SiC particles is 2-4 μm and the D50 particle size of the second β-SiC particles is 6-12 μm, the aluminum-based silicon carbide has better plasticity, rigidity and thermal conductivity. The reason is that when the D50 particle size of the first β-SiC particles and the D50 particle size of the second β-SiC particles are too large or too small, the filling effect of the β-SiC particles in the aluminum-based alloy and the porosity thereof are affected, which results in that the plasticity and rigidity of the aluminum-based silicon carbide cannot be improved well, and the thermal conductivity is also affected.

[0177] Compared with Comparative Example 5, the aluminum-based silicon carbide obtained in Example 3 has higher yield strength, elongation, elastic modulus and thermal conductivity, and smaller single-side edge crack length, which shows that the aluminum-based silicon carbide prepared by using the β-SiC particles with double particle size distribution has better plasticity, rigidity and thermal conductivity. The reason is that the α-SiC particles have higher hardness and lower toughness, and are mostly in the form of flake or needle, which cannot grow into equiaxed particles in the preparation process, and cannot be uniformly dispersed, which affects the distribution of internal stress of the material, and thus affects the plasticity, rigidity and thermal conductivity of the material.

[0178] Compared with Comparative Example 6, the aluminum-based silicon carbide obtained in Example 1 has higher yield strength, elongation, elastic modulus and thermal conductivity, and smaller single-side edge crack length, which shows that the aluminum-based silicon carbide prepared by using the β-SiC particles with double particle size distribution has better plasticity, rigidity and thermal conductivity. The reason is that the β-SiC particles with single particle size have a large number of pores in the alloy matrix, and cannot be dispersed well. In the double particle size distribution, the particles with relatively large particle size can form a skeleton and bear the main load, and the particles with relatively small particle size can fill the gaps formed by the large particles, and the two work together to significantly enhance the plasticity, rigidity and thermal conductivity of the aluminum-based silicon carbide.

[0179] Compared with Comparative Example 7, the aluminum-based silicon carbide obtained in Example 1 has higher yield strength, elongation, elastic modulus and thermal conductivity, and smaller single-side edge crack length, which shows that the aluminum-based silicon carbide prepared by using the β-SiC particles with a sphericity greater than or equal to 0.8 has better plasticity, rigidity and thermal conductivity. The reason is that the smaller the sphericity of the β-SiC particles, the more the edges and corners on the surface of the β-SiC particles, and the edges and corners form natural stress concentration points, which preferentially induce micro-cracks under load, resulting in damage to the material structure, and finally the mechanical properties and thermal conductivity are damaged.

[0180] It should be understood that many of the materials and devices exemplified in this disclosure are articles of manufacture (i.e., articles of manufacture) according to this disclosure. The articles of manufacture can be employed as such to provide advantageous results. The articles of manufacture can also be employed in the practice or testing of the present disclosure. The articles of manufacture can also be employed in the practice or testing of other examples of the present disclosure. The articles of manufacture employed as such for practicing the present disclosure: include those devices and those manufacturing techniques that are known to those of skill in the art in this field. The articles of manufacture employed as such for practicing the present disclosure: include those devices and those manufacturing techniques that are analogous to those devices and those manufacturing techniques that are known to those of skill in the art in this field. The articles of manufacture employed as such for practicing the present disclosure: include those devices and those manufacturing techniques that are later developed by those of skill in the art in this field and are equivalent to those devices and those manufacturing techniques that are known to those of skill in the art in this field.

Claims

1. An aluminum-based silicon carbide characterized by, The mixture comprises aluminum alloy particles and β-silicon carbide particles; The β-silicon carbide particles comprise first β-silicon carbide particles with a D50 of 2 μm-4 μm and second β-silicon carbide particles with a D50 of 6 μm-12 μm; The first β-silicon carbide particles account for 20%-45% of the volume fraction of the β-silicon carbide, and the second β-silicon carbide accounts for 55%-80% of the volume fraction of the β-silicon carbide; The β-silicon carbide particles are spherical particles, and the sphericity of the spherical particles is greater than or equal to 0.

80.

2. The aluminum-based silicon carbide of claim 1, wherein, The β-silicon carbide particles account for 5%-15% of the volume fraction of the aluminum-based silicon carbide.

3. The aluminum-based silicon carbide according to claim 1 or 2, characterized in that, The aluminum alloy particles comprise at least one of 6061-series aluminum alloy particles and 6063-series aluminum alloy particles; And / or, the D50 of the aluminum alloy particles is 5 μm-20 μm.

4. A method of producing the aluminum-based silicon carbide of any one of claims 1 to 3, characterized by, The method comprises: pressing the mixture comprising aluminum alloy particles and β-silicon carbide particles to obtain a green body; sintering the green body to obtain a sintered body; extruding the sintered body to obtain an extruded body; post-processing the extruded body to obtain the aluminum-based silicon carbide.

5. The method of claim 4, wherein the aluminum-based silicon carbide is prepared by the steps of: mixing a silicon source and an aluminum source; and heating the mixture to a temperature of 1,000°C to 1,500°C in a non-oxidizing atmosphere. The relative density of the green body is 85%-95%; and / or the density of the extruded body is 2.76 g / cm 3 - 2.82 g / cm 3 .

6. The method for preparing aluminum-based silicon carbide according to claim 4, characterized in that, The pressing comprises cold isostatic pressing, and the cold isostatic pressing comprises: holding the green body at 200 MPa-300 MPa for 60 s-120 s; And / or, before the sintering, further comprising pure aluminum cladding and vacuum degassing; The vacuum degassing comprises: heating the green body to 400-500°C, holding for 1-10h at a vacuum degree less than or equal to 1x10 -3 Pa; And / or, the sintering comprises atmospheric sintering, and the atmospheric sintering comprises: heating the green body to 580 ℃-630 ℃ at a heating rate of 5 ℃ / min-10 ℃ / min, and sintering for 6 h-10 h.

7. The method for preparing aluminum-based silicon carbide according to claim 4, characterized in that, The extrusion comprises: primary extrusion: extruding the sintered body at an extrusion ratio (4-8):1 to obtain an extruded intermediate; secondary extrusion: extruding the extruded intermediate at an extrusion ratio (10-25):1 to obtain an extruded body; During the primary extrusion, the temperature of the sintered body is 480 ℃-520 ℃, and the extrusion speed is 2 mm / s-5 mm / s; And / or, during the secondary extrusion, the temperature of the extruded intermediate is 450 ℃-480 ℃; And / or, between the primary extrusion and the secondary extrusion, further comprising water mist cooling, and the cooling rate of the water mist cooling is greater than or equal to 50 ℃ / s.

8. The method for preparing aluminum-based silicon carbide according to claim 4, characterized in that, The post-processing comprises water quenching treatment and aging treatment; During the water quenching treatment, the temperature of the extruded body is 500 ℃-560 ℃, and the time of the water quenching treatment is 20 min-30 min; The temperature of the aging treatment is 170 ℃-180 ℃, and the treatment time is 7 h-9 h.

9. A heat dissipation piece comprising the aluminum-based silicon carbide according to any one of claims 1-3 or prepared by the preparation method according to any one of claims 4-8.

Images