High-strength and high-heat-conductivity SiCp / Al composite material joint and preparation method thereof

Abstract

The invention provides a high-strength and high-heat-conductivity SiCp / Al composite material joint and a preparation method thereof, and relates to the technical field of welding, the method comprises the following steps: pretreating a to-be-welded surface of a SiCp / Al composite material to obtain a to-be-welded part; a middle layer, a diamond particle layer and a middle layer are sequentially arranged between the to-be-welded faces of the two to-be-welded parts, and an assembly part is obtained; wherein the middle layer is made of an Au-Si alloy; and under the vacuum condition, preset pressure is applied to the assembly part, the assembly part is heated to the welding temperature, heat preservation is conducted for preset time, the assembly part is cooled to the room temperature, and the SiCp / Al composite material connector is obtained. By adopting the method disclosed by the invention, the SiCp / Al composite material joint with relatively high strength and relatively high heat conductivity can be obtained.

Description

Technical Field

[0001] The present invention relates to the field of welding technology, and more particularly, to a high-strength and high-thermal-conductivity SiCp / Al composite joint and a preparation method thereof. Background Art

[0002] The SiCp / Al composite material is a multiphase composite structural material with aluminum or aluminum alloy as the matrix and silicon carbide particles (SiC) as the reinforcing phase. The SiCp / Al composite material has excellent properties such as light weight, high strength, high specific stiffness, and high thermal conductivity, and is an ideal raw material for preparing heat dissipation microchannel devices. The main method for preparing the heat dissipation microchannel is hot pressing diffusion welding. However, since the weldable temperature of the SiC ceramic particle reinforcing phase inside the base material is much higher than the melting point of the aluminum alloy matrix. The traditional hot pressing diffusion welding temperature needs to be above 90% of the melting point of the base material, otherwise it is impossible to drive the atomic diffusion and interface healing at the weld position, which will cause a large amount of deformation and damage to the microstructure during the welding process of the base material. In addition, there are a large number of "aluminum / ceramic" and "ceramic / ceramic" two non-welded regions in the joint obtained by hot pressing diffusion welding, resulting in low strength and low thermal conductivity of the joint, which cannot meet the application requirements of the heat dissipation microchannel. Therefore, for the hot pressing diffusion welding of SiCp / Al composite materials, how to obtain a SiCp / Al composite joint with higher strength and higher thermal conductivity has become an urgent technical problem to be solved. Summary of the Invention

[0003] The problem solved by the present invention is: for the hot pressing diffusion welding of SiCp / Al composite materials, how to obtain a SiCp / Al composite joint with higher strength and higher thermal conductivity.

[0004] To solve the above problems, the present invention provides a preparation method for a high-strength and high-thermal-conductivity SiCp / Al composite joint, including:

[0005] Step S1, pre-treat the welding surface of the SiCp / Al composite material to obtain a workpiece to be welded;

[0006] Step S2, sequentially arrange an intermediate layer, a diamond particle layer, and an intermediate layer between the welding surfaces of the two workpieces to be welded to obtain an assembled part; wherein, the material of the intermediate layer is an Au-Si alloy;

[0007] Step S3, under vacuum conditions, apply a preset pressure to the assembled part, heat the assembled part to the welding temperature, keep it warm for a preset time, and cool it to room temperature to obtain a SiCp / Al composite joint.

[0008] Optionally, in the step S1, the pre-treatment of the welding surface of the SiCp / Al composite material includes: sequentially grinding, cleaning, and drying the welding surface of the SiCp / Al composite material.

[0009] Optionally, in step S1, the pretreatment of the welding surface of the SiCp / Al composite material further includes: bombarding the dried welding surface with argon ions.

[0010] Optionally, the energy of the argon ion bombardment is 200 eV to 900 eV, and the time is 10 min to 60 min.

[0011] Optionally, in step S2, the thickness of the intermediate layer is 0.05 mm to 0.2 mm, and the mass fraction of Si atoms in the Au-Si alloy is 30% to 40%.

[0012] Optionally, in step S2, the thickness of the diamond particle layer is 0.01 mm to 0.1 mm, and the particle size of the diamond particles in the diamond particle layer is 300 mesh to 600 mesh.

[0013] Optionally, in step S3, the heating of the assembly to the welding temperature is achieved by applying a pulsed current, and the direction of the pulsed current is perpendicular to the welding surface of the SiCp / Al composite material.

[0014] Optionally, in step S1, the SiCp / Al composite material includes an aluminum matrix and SiC particle reinforcement phases, and the volume fraction of SiC particles in the SiCp / Al composite material is 15% to 70%.

[0015] Optionally, the aluminum matrix is selected from at least one of aluminum, 8011 aluminum alloy, 6061 aluminum alloy, 6063 aluminum alloy, 5A06 aluminum alloy, 5052 aluminum alloy, 4004 aluminum alloy, 4032 aluminum alloy, 3003 aluminum alloy, 2024 aluminum alloy, 2A12 aluminum alloy, and ZL101 aluminum alloy.

[0016] The present invention also provides a high-strength and high-thermal conductivity SiCp / Al composite material joint, which is prepared by using the preparation method of the high-strength and high-thermal conductivity SiCp / Al composite material joint as described above.

[0017] Compared with the related technologies, in the hot press diffusion welding of SiCp / Al composites, an Au-Si alloy interlayer, a diamond particle layer, and an Au-Si alloy interlayer are sequentially arranged between the welding surfaces of two SiCp / Al composite workpieces to be welded. Among them, under the action of the concentration gradient, the Si element in the Au-Si alloy interlayer will diffuse towards the SiCp / Al composite base material side and form a bond with the SiC particles at the interface through Si-Si bonds, thereby eliminating the two unwelded areas of "aluminum / ceramic" and "ceramic / ceramic", and greatly improving the strength of the SiCp / Al composite joint. In addition, as the welding process progresses, the Si element in the Au-Si alloy interlayer will completely diffuse to the interface and the SiCp / Al composite base material, resulting in the formation of a pure Au phase in the joint part, thereby making the SiCp / Al composite joint have a high thermal conductivity. Moreover, while the Si element diffuses into the SiCp / Al composite base material, the Al element in the base material will also diffuse into the interlayer. Al has good solid solubility in Au, so the Al element diffusing into the interlayer will form a gradient Au(Al) solid solution phase at the "base material / interlayer" interface, playing a good transition role between the base material and the pure Au phase, reducing the residual stress of the joint, and thus being beneficial to further improving the strength of the SiCp / Al composite joint. In addition, diamond particles are introduced between the two Au-Si alloy interlayers. Since diamond particles are insulators, under the action of the thermal field, the "diamond / Au-Si interlayer" interface will have an instantaneous high temperature due to excessive thermal resistance, resulting in the melting of the Au-Si alloy here. The melted Au-Si alloy will coat the diamond particles into the liquid phase to form a diamond particle-reinforced Au-based composite joint, thereby further improving the strength of the SiCp / Al composite joint. At the same time, due to the high thermal conductivity of diamond particles, the thermal conductivity of the SiCp / Al composite joint can be further improved. In summary, by using the method of the present invention, a SiCp / Al composite joint with high strength and high thermal conductivity can be obtained. Description of the Drawings

[0018] Figure 1 It is a schematic diagram when hot press diffusion welding is performed on the assembled parts in the embodiment of the present invention.

[0019] Description of the Reference Numerals:

[0020] 1. SiCp / Al composite material; 2. Interlayer; 3. Diamond particle layer; 4. Upper graphite punch; 5. Lower graphite punch; 6. Upper electrode; 7. Lower electrode. Detailed Embodiments

[0021] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following will describe in detail the specific embodiments of the present invention with reference to the accompanying drawings. Although some embodiments of the present invention are shown in the drawings, it should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments described herein. On the contrary, these embodiments are provided to more thoroughly and completely understand the present invention. It should be understood that the drawings and embodiments of the present invention are only for exemplary purposes and are not used to limit the protection scope of the present invention.

[0022] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used in the present invention in the specification are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0023] The term "including" and its variants used herein are open-ended, that is, "including but not limited to"; the term "based on" is "at least partially based on"; the term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment"; the term "some embodiments" means "at least some embodiments"; the term "optionally" means "optional embodiment". The relevant definitions of other terms will be given in the following description. It should be noted that the concepts of "first", "second", etc. mentioned in the present invention are used to distinguish different objects and are not used to describe a specific order or primary-secondary relationship. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, unless otherwise specified, the meaning of "a plurality" is two or more. It should be noted that in the present invention, the deformation rate refers to the ratio of the volume or shape change of the joint part due to factors such as heat input, material properties, and process constraints after welding to the original geometric dimensions.

[0024] A method for preparing a high-strength and high-thermal conductivity SiCp / Al composite joint provided by an embodiment of the present invention includes:

[0025] Step S1: Pretreat the weldable surface of the SiCp / Al composite material 1 to obtain a workpiece to be welded;

[0026] Step S2: Sequentially arrange an intermediate layer, a diamond particle layer, and an intermediate layer between the weldable surfaces of the two workpieces to be welded to obtain an assembly. As Figure 1 shown, the arrangement order of each component in the assembly is the workpiece to be welded, the intermediate layer 2, the diamond particle layer 3, the intermediate layer 2, and the workpiece to be welded; wherein, the material of the intermediate layer 2 is an Au-Si alloy;

[0027] Step S3: Under vacuum conditions, apply a preset pressure to the assembly and heat the assembly to the welding temperature, keep it warm for a preset time, and then cool it to room temperature to obtain a SiCp / Al composite joint.

[0028] In the embodiment of the present invention, in the hot press diffusion welding of SiCp / Al composites, an Au-Si alloy intermediate layer, a diamond particle layer, and an Au-Si alloy intermediate layer are sequentially arranged between the weld surfaces of two SiCp / Al composite workpieces to be welded. Among them, under the action of the concentration gradient, the Si element in the Au-Si alloy intermediate layer will diffuse towards the SiCp / Al composite base material side, and form a bond with the SiC particles at the interface through Si-Si bonds, thereby eliminating the two unwelded regions of "aluminum / ceramic" and "ceramic / ceramic", and greatly improving the strength of the SiCp / Al composite joint. In addition, as the welding process progresses, the Si element in the Au-Si alloy intermediate layer will completely diffuse into the interface and the SiCp / Al composite base material, resulting in the formation of a pure Au phase in the joint part, so that the SiCp / Al composite joint has a high thermal conductivity. Moreover, while the Si element diffuses into the SiCp / Al composite base material, the Al element in the base material will also diffuse into the intermediate layer. Al has good solid solubility in Au, so the Al element diffusing into the intermediate layer will form a gradient Au(Al) solid solution phase at the "base material / intermediate layer" interface, playing a good transition role between the base material and the pure Au phase, reducing the residual stress of the joint, and thus being beneficial to further improving the strength of the SiCp / Al composite joint. In addition, diamond particles are introduced between the two Au-Si alloy intermediate layers. Since diamond particles are insulators, under the action of the thermal field, the "diamond / Au-Si intermediate layer" interface will have an instantaneous high temperature due to excessive thermal resistance, resulting in the melting of the Au-Si alloy here. The melted Au-Si alloy will coat the diamond particles into the liquid phase to form a diamond particle-reinforced Au-based composite joint, thereby further improving the strength of the SiCp / Al composite joint. At the same time, due to the high thermal conductivity of diamond particles, the thermal conductivity of the SiCp / Al composite joint can be further improved. In summary, by using the method of the embodiment of the present invention, a SiCp / Al composite joint with high strength and high thermal conductivity can be obtained.

[0029] In some embodiments of the present invention, in step S1, the pretreatment of the weld surface of the SiCp / Al composite 1 includes: sequentially grinding, cleaning, and drying the weld surface of the SiCp / Al composite 1.

[0030] In some embodiments of the present invention, preferably, in the step S1, the pretreatment of the welding surface of the SiCp / Al composite material includes: successively grinding, cleaning, drying, and argon ion bombardment of the welding surface of the SiCp / Al composite material. In this embodiment, by activating and modifying the welding surface of the SiCp / Al composite material through argon ion bombardment, the surface energy of the atoms on the surface of the SiCp / Al composite material base metal is increased, the welding temperature is reduced, the possibility of plastic deformation of the SiCp / Al composite material base metal can be reduced, and thus the deformation rate of the SiCp / Al composite material joint can be further reduced. In addition, by activating and modifying the welding surface of the SiCp / Al composite material through argon ion bombardment, the wettability between the intermediate layer alloy and the base metal surface is also improved, the diffusion rate of Al in the base metal and the Au-Si intermediate layer is increased, the welding time is shortened, which is beneficial to further improving the welding efficiency.

[0031] In some embodiments of the present invention, the energy of the argon ion bombardment is 200 eV to 900 eV, and the time is 10 min to 60 min.

[0032] In some embodiments of the present invention, in the step S2, the thickness of the intermediate layer is 0.05 mm to 0.2 mm, and the mass fraction of Si atoms in the Au-Si alloy is 30% to 40%.

[0033] In some embodiments of the present invention, in the step S2, the thickness of the diamond particle layer is 0.01 mm to 0.1 mm, and the particle size of the diamond particles in the diamond particle layer is 300 mesh to 600 mesh.

[0034] In some embodiments of the present invention, in the step S3, the heating of the assembly to the welding temperature is achieved by the action of a pulsed current, and the direction of the pulsed current is perpendicular to the welding surface of the SiCp / Al composite material. In this embodiment, the plasma activation effect generated by the pulsed current can further reduce the diffusion welding temperature of the SiCp / Al composite material, avoid the severe deformation of the SiCp / Al composite material under the action of high temperature and high pressure, prevent the large deformation of the welded joint, and is beneficial to further reducing the deformation rate of the SiCp / Al composite material joint.

[0035] In some embodiments of the present invention, in the step S3, the duty cycle of the pulsed current is 25% to 100%, the nominal peak current density is 3 A / mm 2 to 8 A / mm 2 , and the frequency is 50 Hz to 100 Hz.

[0036] In some embodiments of the present invention, in step S1, the SiCp / Al composite material includes an aluminum matrix and a SiC particle reinforcement phase. The volume fraction of SiC particles in the SiCp / Al composite material is 15% to 70%, and the size of the SiC particles is in the micron range.

[0037] In some embodiments of the present invention, the aluminum matrix is selected from at least one of aluminum, 8011 aluminum alloy, 6061 aluminum alloy, 6063 aluminum alloy, 5A06 aluminum alloy, 5052 aluminum alloy, 4004 aluminum alloy, 4032 aluminum alloy, 3003 aluminum alloy, 2024 aluminum alloy, 2A12 aluminum alloy, and ZL101 aluminum alloy.

[0038] In some embodiments of the present invention, in step S3, the welding temperature is 420°C to 480°C, the preset time is 30 min to 60 min, and the preset pressure is 3 MPa to 15 MPa.

[0039] The embodiments of the present invention also provide a high-strength and high-thermal-conductivity SiCp / Al composite material joint, which is prepared by using the preparation method of the high-strength and high-thermal-conductivity SiCp / Al composite material joint as described above.

[0040] The present invention will be further described below in conjunction with specific embodiments.

[0041] Example 1

[0042] A1. Pretreat the welding surface of the SiCp / Al composite material 1 to obtain a workpiece to be welded. Among them, the pretreatment of the welding surface of the SiCp / Al composite material includes: successively grinding, cleaning, and drying the welding surface of the SiCp / Al composite material. The SiCp / Al composite material includes an aluminum matrix and a SiC particle reinforcement phase. The aluminum matrix is aluminum, and the ceramic reinforcement phase is micron-sized SiC particles. The volume fraction of SiC particles in the SiCp / Al composite material is 15% to 70%. The SiCp / Al composite material is a cylinder with a diameter of 55 mm and a height of 10 mm.

[0043] A2. As Figure 1 shown, an intermediate layer 2, a diamond particle layer 3, and an intermediate layer 2 are successively arranged between the welding surfaces of the two workpieces to be welded to obtain an assembled part. Among them, the material of the intermediate layer 2 is Au-Si alloy, the mass fraction of Si atoms in the Au-Si alloy is 35%, and the thickness of the intermediate layer is 0.1 mm. The thickness of the diamond particle layer is 0.05 mm, and the particle size of the diamond particles in the diamond particle layer is 450 mesh.

[0044] A3. Place the assembly in a diffusion welding device. After evacuating the air, apply a vertical pressure to the assembly through the upper graphite pressure head 4 and the lower graphite pressure head 5, and heat the assembly to the welding temperature under the action of a pulsed current. Keep the temperature for a preset time, and then cool it to room temperature to obtain a SiCp / Al composite joint. Among them, the direction of the pulsed current is perpendicular to the welding surface of the SiCp / Al composite material. The pulsed current is introduced by connecting the upper electrode 6 and the lower electrode 7 to an external pulsed power supply. The duty cycle of the pulsed current is 50%, and the nominal peak current density is 5 A / mm 2 , and the frequency is 75 Hz; the welding temperature is 450 °C, the preset time is 45 min, and the preset pressure is 9 MPa.

[0045] It should be noted that Figure 1 in, the thick arrow on the upper side represents the vertical downward pressure applied to the assembly, the thick arrow on the lower side represents the vertical upward pressure applied to the assembly, and the vertical downward dotted arrow represents the direction of the pulsed current.

[0046] Example 2

[0047] The difference from Example 1 is that:

[0048] In step A1, the pretreatment of the welding surface of the SiCp / Al composite material includes: sequentially grinding, cleaning, drying, and argon ion bombardment of the welding surface of the SiCp / Al composite material; the energy of the argon ion bombardment is 550 eV, and the time is 35 min.

[0049] Step A3 is: Place the assembly in a diffusion welding device. After evacuating the air, apply a vertical pressure to the assembly through the upper graphite pressure head 4 and the lower graphite pressure head 5, and heat the assembly to the welding temperature under the action of thermal radiation. Keep the temperature for a preset time, and then cool it to room temperature to obtain a SiCp / Al composite joint. Among them, the welding temperature is 450 °C, the preset time is 45 min, and the preset pressure is 9 MPa.

[0050] Example 3

[0051] The difference from Example 1 is that:

[0052] In step A1, the pretreatment of the welding surface of the SiCp / Al composite material includes: sequentially grinding, cleaning, drying, and argon ion bombardment of the welding surface of the SiCp / Al composite material; the energy of the argon ion bombardment is 550 eV, and the time is 35 min.

[0053] Comparative Example 1

[0054] The difference from Example 3 is that:

[0055] Step A2 is: only a diamond particle layer is provided between the welding surfaces of the two workpieces to be welded, obtaining an assembly; wherein, the thickness of the diamond particle layer is 0.05 mm, and the particle size of the diamond particles in the diamond particle layer is 450 mesh.

[0056] Comparative Example 2

[0057] The difference from Example 3 is:

[0058] A2. Only two intermediate layers 2 are provided between the welding surfaces of the two workpieces to be welded, obtaining an assembly; wherein, the material of the intermediate layer is Au-Si alloy, the mass fraction of Si atoms in the Au-Si alloy is 35%, and the thickness of the intermediate layer is 0.1 mm.

[0059] Experimental Example

[0060] The deformation rate shear strength and thermal conductivity of the SiCp / Al composite material joints prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were detected, and the results are shown in Table 1. It can be seen from Table 1 that compared with Comparative Examples 1 to 2, the SiCp / Al composite material joints prepared in Examples 1 to 3 have higher thermal conductivity and higher shear strength. Compared with Example 1, the SiCp / Al composite material joint prepared in Example 3 has higher thermal conductivity, higher shear strength, and lower deformation rate, indicating that argon ion bombardment of the SiCp / Al composite material joint is beneficial to further improving the thermal conductivity and shear strength of the SiCp / Al composite material joint, and is beneficial to further reducing the deformation rate of the SiCp / Al composite material joint. Compared with Example 2, the SiCp / Al composite material joint prepared in Example 3 has higher thermal conductivity, higher shear strength, and lower deformation rate, indicating that heating the assembly to the welding temperature under the action of pulsed current is beneficial to further improving the thermal conductivity and shear strength of the SiCp / Al composite material joint, and is beneficial to further reducing the deformation rate of the SiCp / Al composite material joint.

[0061] Table 1

[0062]

[0063]

[0064] Although the present invention is disclosed as above, the protection scope of the present invention is not limited thereto. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention, and these changes and modifications will all fall within the protection scope of the present invention.

Claims

1. A method for preparing a high-strength, high-thermal-conductivity SiCp / Al composite material joint, characterized in that: include: Step S1, pre-treating the surface to be welded of the SiCp / Al composite material (1) to obtain a welded part; Step S2, sequentially arranging an intermediate layer (2), a diamond particle layer (3) and an intermediate layer (2) between the surfaces to be welded of the two parts to be welded, to obtain an assembly part; wherein the material of the intermediate layer (2) is Au-Si alloy; Step S3: Under vacuum conditions, applying a preset pressure to the assembly, heating the assembly to a welding temperature, keeping the temperature for a preset time, and cooling to room temperature to obtain a SiCp / Al composite material joint.

2. The method for preparing a high-strength, high-thermal-conductivity SiCp / Al composite material joint according to claim 1, characterized in that: In the step S1, the pretreatment of the surface to be welded of the SiCp / Al composite material includes: grinding, cleaning and drying the surface to be welded of the SiCp / Al composite material in sequence.

3. The method for preparing a high-strength, high-thermal-conductivity SiCp / Al composite material joint according to claim 2, characterized in that: In the step S1, the pretreatment of the surface to be welded of the SiCp / Al composite material further includes: bombarding the dried surface to be welded with argon ions.

4. The method for preparing a high-strength, high-thermal-conductivity SiCp / Al composite material joint according to claim 3, characterized in that: The energy of the argon ion bombardment is 200 eV to 900 eV, and the time is 10 min to 60 min.

5. The method for preparing a high-strength, high-thermal-conductivity SiCp / Al composite material joint according to claim 1, characterized in that: In the step S2, the thickness of the intermediate layer (2) is 0.05 mm to 0.2 mm, and the mass fraction of Si atoms in the Au-Si alloy is 30% to 40%.

6. The method for preparing a high-strength, high-thermal-conductivity SiCp / Al composite material joint according to claim 1, characterized in that: In the step S2, the thickness of the diamond particle layer (3) is 0.01 mm to 0.1 mm, and the particle size of the diamond particles in the diamond particle layer (3) is 300 mesh to 600 mesh.

7. The method for preparing a high-strength, high-thermal-conductivity SiCp / Al composite material joint according to claim 1, characterized in that: In the step S3, the heating of the assembly to the welding temperature is achieved by pulse current, and the direction of the pulse current is perpendicular to the surface to be welded of the SiCp / Al composite material.

8. The method for preparing a high-strength, high-thermal-conductivity SiCp / Al composite material joint according to claim 1, characterized in that: In step S1, the SiCp / Al composite material includes an aluminum matrix and a SiC particle reinforcement phase, and the volume fraction of SiC particles in the SiCp / Al composite material is 15% to 70%.

9. The method for preparing a high-strength, high-thermal-conductivity SiCp / Al composite material joint according to claim 8, characterized in that: The aluminum matrix is ​​selected from at least one of aluminum, 8011 aluminum alloy, 6061 aluminum alloy, 6063 aluminum alloy, 5A06 aluminum alloy, 5052 aluminum alloy, 4004 aluminum alloy, 4032 aluminum alloy, 3003 aluminum alloy, 2024 aluminum alloy, 2A12 aluminum alloy and ZL101 aluminum alloy.

10. A high-strength, high-thermal-conductivity SiCp / Al composite material joint, characterized in that: The method for preparing a high-strength and high-thermal-conductivity SiCp / Al composite material joint is used.

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