Method for joining single crystal aluminum by spark plasma sintering, single crystal aluminum weld joint
By performing plasma selective etching and low-temperature, low-pressure discharge plasma sintering on the welding surface of single-crystal aluminum, the problems of high temperature, long time consumption, and large deformation in single-crystal aluminum welding were solved, achieving a highly efficient and reliable welding effect.
Patent Information
- Application Number
- CN202310746543.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-25
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2043-06-25
AI Technical Summary
The spark plasma sintering technology has problems in welding single crystal aluminum, such as high welding temperature, long welding time, and large deformation due to the softness of aluminum, which leads to reduced welding quality.
Before welding, the surfaces of the workpieces to be welded are subjected to plasma selective etching. Through selective etching, the atoms on the surfaces to be welded are in the same bonding state, reducing the surface roughness to the angstrom level. Then, discharge plasma sintering is performed at low temperature and low pressure.
It improves welding efficiency, reduces welding time, lowers temperature and external pressure, improves welding quality, achieves a welding rate of 95-98%, and sintering time does not exceed 2 hours.
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Figure CN117001127B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of plasma sintering, in particular to a method for connecting single crystal aluminum by using spark plasma sintering and a single crystal aluminum welded joint. BACKGROUND
[0002] Spark plasma sintering (SPS) refers to the process of directly passing pulse current into a mold and powder particles or block samples to perform sintering or connection, also known as plasma activated sintering (PAS) or pulse current pressure sintering. SPS integrates plasma spark, hot pressing and resistance heating, and has many advantages compared with traditional sintering technology. However, there are still problems such as high welding temperature and long time consumption when using spark plasma sintering to weld single crystal aluminum. In addition, due to the softness of aluminum, the deformation during welding is large, which reduces the welding quality. SUMMARY
[0003] The present application solves at least one of the following problems: when using spark plasma sintering to weld single crystal aluminum, there are still problems such as high welding temperature and long time consumption, and in addition, due to the softness of aluminum, the deformation during welding is large, which reduces the welding quality.
[0004] To solve the above technical problems, the technical scheme adopted by the present application is as follows:
[0005] A method for connecting single crystal aluminum by using spark plasma sintering, comprising:
[0006] Step S1, surface cleaning treatment is performed on a single crystal aluminum sample to obtain a pretreated welding piece;
[0007] Step S2, surface treatment is performed on the welding surface of the pretreated welding piece to obtain an intermediate welding piece; the surface treatment includes plasma selective etching treatment;
[0008] Step S3, the welding surfaces of the intermediate welding pieces are overlapped and butted together, and spark plasma sintering treatment is performed to connect the intermediate welding pieces together to obtain a single crystal aluminum welded joint.
[0009] Optionally, in the step S2, the plasma gas used in the plasma selective etching treatment includes a first gas and O2, and the first gas includes at least one of CCl4 and CF4.
[0010] Optionally, in the step S2, the plasma gas includes CCl4 and O2, and the molar ratio of CCl4 to O2 in the plasma gas is (1-1.3):1.
[0011] Optionally, in the step S2, the plasma gas comprises CF4 and O2, and the molar ratio of CF4 to O2 in the plasma gas is (1-1.3) : 1.
[0012] Optionally, in the step S2, the plasma selective etching treatment is performed under the protection of argon by using atmospheric pressure inductive coupled plasma, and the power of the plasma selective etching treatment is 50-200 W, the temperature is 200-300 ℃, the time is 1-10 min, the voltage is 300-600 V, the beam current intensity is 50-200 mA, and the argon flow rate is 10-30 sccm.
[0013] Optionally, in the step S2, the surface treatment further comprises coating a protective liquid on the surface to be welded of the welding piece after the plasma selective etching treatment.
[0014] Optionally, in the step S3, the temperature of the discharge plasma sintering treatment is 350-500 ℃, the pressure is 5-15 MPa, and the time is 0.5-1 h.
[0015] Optionally, in the step S1, the surface cleaning treatment of the single-crystal aluminum sample comprises: sequentially cleaning the single-crystal aluminum sample with acetone, sodium hydroxide solution, anhydrous ethanol and nitric acid solution, polishing treatment, and cleaning again.
[0016] Optionally, the mass fraction of the sodium hydroxide solution is 5-10%, and the volume fraction of the nitric acid solution is 12-20%.
[0017] Compared with the prior art, the application carries out plasma selective etching treatment on the welding surface of the to-be-welded part before carrying out the discharge plasma sintering welding on the single crystal aluminum, the plasma selective etching treatment realizes selective etching by different selection of different bond state atoms, so that the atoms on the welding surface of the to-be-welded part are in the same bond state, the roughness of the welding surface of the to-be-welded part is reduced to the order of magnitude of angstrom, that is, the roughness of the welding surface of the to-be-welded part is lower, the number of atoms in mutual contact between the welding surfaces of the to-be-welded part is greatly increased, which is beneficial to the mutual diffusion of atoms during the subsequent discharge plasma sintering treatment of the single crystal aluminum, so that the welding efficiency is improved and the welding time is reduced; since the mutual diffusion effect of atoms is better, the temperature can be appropriately reduced during the welding by using the discharge plasma sintering technology; since the mutual diffusion effect of atoms is better, the external pressure for reducing the distance between atoms of the to-be-welded part can be appropriately reduced during the welding by using the discharge plasma sintering technology, the reduction of the external pressure is beneficial to reducing the deformation of aluminum and improving the welding quality. By using the method of the application, the elemental aluminum can be reliably connected under the condition of being lower than the traditional diffusion welding connection temperature by 100-150 DEG C, the welding rate can reach 95-98 %, and the sintering time is not more than 2h.
[0018] The application further provides a single crystal aluminum welding joint prepared by using the method for connecting single crystal aluminum by discharge plasma sintering as described above. BRIEF DESCRIPTION OF DRAWINGS
[0019] Figure 1 It is a flowchart of the method for connecting single crystal aluminum by discharge plasma sintering in the embodiments of the application. DETAILED DESCRIPTION
[0020] In order to make the above objectives, characteristics and advantages of the application more obvious and easy to understand, the specific embodiments of the application are described in detail below with reference to the drawings.
[0021] It should be noted that the features in the embodiments of the application can be combined with each other without conflict. The terms “contain”, “include”, “have”, “possess” have the meaning of non-limitation, that is, other steps and other components that do not affect the results can be added. The above terms cover the terms “consist of” and “consist essentially of”. Unless otherwise specified, the materials, devices and reagents are commercially available.
[0022] The essence of welding by the spark plasma sintering technology (SPS) is still diffusion connection, and the principle is that the surfaces of the materials in contact with each other are close to each other under the action of temperature and pressure, local plastic deformation occurs, interatomic diffusion occurs, and a diffusion layer is formed at the interface contact, so as to realize reliable connection. In order to improve the interatomic diffusion effect, the atoms between the materials need to be as close as possible. At present, the surface treatment technology applied to the welding parts is that the surface of the treated welding part is macroscopically smooth, but it is still uneven under the microscope, which leads to the fact that the welding parts are actually not in surface contact but in point contact at the micro level; a large number of randomly distributed atoms hinder each other, so that only part of the atoms can directly contact, and the diffusion effect between the atoms needs to be further improved. Therefore, the welding by the spark plasma sintering technology also has problems of high welding temperature and long time consumption; in addition, since aluminum is soft, in the process of diffusion welding by the spark plasma sintering technology (SPS), a large pressure is often applied during welding to shorten the distance between the atoms of the welding parts, which may cause excessive deformation of the metal and reduce the welding quality when welding soft metal materials such as aluminum.
[0023] Based on the above considerations, as shown in Figure 1 The embodiment of the present application provides a method for connecting single crystal aluminum by spark plasma sintering, which comprises the following steps:
[0024] Step S1, surface cleaning treatment is performed on a single crystal aluminum sample to obtain a pretreated welding part;
[0025] Step S2, surface treatment is performed on the welding surface of the pretreated welding part to obtain an intermediate welding part; the surface treatment comprises plasma selective etching treatment;
[0026] Step S3, the welding surfaces of the intermediate welding parts are overlapped and butted together, and spark plasma sintering treatment is performed to connect the intermediate welding parts together to obtain a single crystal aluminum welding joint.
[0027] It should be noted that the welding surfaces of the intermediate welding parts are overlapped and butted together, which means that the welding surfaces of a plurality of intermediate welding parts are overlapped and butted together, for example, the welding surfaces of two intermediate welding parts are overlapped and butted together. The plasma selective etching treatment is an advanced etching technology based on atomic level etching behavior and mechanism of plasma, which realizes selective etching by selecting different bond state atoms, and finally forms an equipotential surface in which all surface atoms are in the same state, that is, an atomic level perfect surface.
[0028] Compared with the prior art, the embodiment of the present application carries out plasma selective etching treatment on the welding surface of the welding piece before carrying out the discharge plasma sintering welding on the single crystal aluminum, the plasma selective etching treatment realizes selective etching by different selection of different bond state atoms, so that the atoms on the welding surface of the welding piece are in the same bond state, the roughness of the welding surface of the welding piece is reduced to the order of magnitude of angstrom, that is, the roughness of the welding surface of the welding piece is lower, the number of atoms in contact with each other between the welding surfaces of the welding piece is greatly increased, which is beneficial to the mutual diffusion of atoms during the subsequent discharge plasma sintering treatment on the single crystal aluminum, so that the welding efficiency is improved and the welding time is reduced; due to the better mutual diffusion effect of atoms, the temperature can be appropriately reduced during welding by using the discharge plasma sintering technology; due to the better mutual diffusion effect of atoms, the external pressure for reducing the distance between atoms of the welding piece can be appropriately reduced during welding by using the discharge plasma sintering technology, the reduction of the external pressure is beneficial to reducing the deformation of aluminum and improving the welding quality. By using the method of the present application, the elemental aluminum can be reliably connected at a temperature 100-150 DEG C lower than the traditional diffusion welding connection temperature, the welding rate can reach 95-98 %, and the sintering time is not more than 2 h.
[0029] In the embodiment of the present application, in the step S2, the plasma gas used in the plasma selective etching treatment includes a first gas and O2, and the first gas includes at least one of CCl4 and CF4. Al can better react with these plasma gases, for example, the reaction of Al etched by CCl4 and O2 is as follows:
[0030] 4Al + 3O2→ 2Al2O3↑
[0031] CCl4 + e→ CCl3 + + Cl + 2e
[0032] Al2O3 + 2Cl3 + → 2AlCl3↑ + CO + CO2↑
[0033] Al + 3Cl→ AlCl3↑
[0034] In the embodiment of the present application, in the step S2, the plasma gas includes CCl4 and O2, and the molar ratio of CCl4 to O2 in the plasma gas is (1-1.3):1.
[0035] In the embodiment of the present application, in the step S2, the plasma gas includes CF4 and O2, and the molar ratio of CF4 to O2 in the plasma gas is (1-1.3):1.
[0036] In the step S2, the plasma selective etching treatment is performed under the protection of argon by using atmospheric pressure inductive coupled plasma, the power of the plasma selective etching treatment is 50-200 W, the temperature is 200-300 ℃, the time is 1-10 min, the voltage is 300-600 V, the beam current intensity is 50-200 mA, and the argon flow is 10-30 sccm. The atomic selective etching technology based on plasma refers to that after the machining process such as grinding or polishing, the main influencing factor of the surface roughness of the material is the redundant atoms or atomic layers randomly distributed on a perfect crystal face. According to the different bonding states, the above-mentioned rough surface atoms can be divided into two categories: the atoms at the end of the step and the atoms in the step face. Since the end atoms and the in-plane atoms have different bonding states, their reaction activities are bound to be different, and this difference directly leads to different plasma etching rates. In the embodiment of the present application, by controlling the occurrence conditions of the plasma etching reaction, the etching rate difference of the material can be accurately controlled, so as to obtain a nearly perfect complete crystal surface, so that the surface roughness of the to-be-welded part is reduced to the order of angstrom or sub-angstrom, that is, a perfect atomic level surface is obtained. The argon is used for protection of the to-be-welded part to prevent oxidation.
[0037] In the step S2, the surface treatment further includes coating a protective liquid on the to-be-welded surface of the to-be-welded part after the plasma selective etching treatment, and the protective liquid is washed off before the intermediate to-be-welded part is welded. Illustratively, the protective liquid includes at least one of terpineol and ethylene glycol. Coating the protective liquid on the to-be-welded surface of the to-be-welded part after the plasma selective etching treatment can prevent the surface of the to-be-welded part from being oxidized in the air, so that an oxide layer is not generated on the surface of the to-be-welded part before welding, and the subsequent welding effect is affected. Coating the protective liquid on the to-be-welded surface of the to-be-welded part after the plasma selective etching treatment can prevent the surface of the to-be-welded part from being oxidized before welding, so that the welding quality is higher.
[0038] In the step S3, the intermediate to-be-welded part is subjected to a discharge plasma sintering treatment by using an SPS diffusion furnace, the temperature of the discharge plasma sintering treatment is 350-500 ℃, the pressure is 5-15 MPa, and the time is 0.5-1 h. The temperature of the discharge plasma sintering treatment should be lower than the softening temperature of aluminum, and due to the existence of the electroplastic effect in the SPS diffusion welding process, the actual welding temperature should be lower. Illustratively, the heating process of the discharge plasma sintering treatment is as follows: first, heating from room temperature to 200 ℃ at a speed of 50-100 ℃ / min, and then heating from 200 ℃ to the set temperature of the discharge plasma sintering treatment at a speed of 20-50 ℃ / min. The temperature change in the above-mentioned heating process is more stable, which is more conducive to welding.
[0039] In the step S1, the surface cleaning treatment of the single crystal aluminum sample comprises: sequentially cleaning the single crystal aluminum sample with acetone, sodium hydroxide solution, anhydrous ethanol and nitric acid solution, polishing treatment, and cleaning again. The mass fraction of the sodium hydroxide solution is 5-10%, and the volume fraction of the nitric acid solution is 12-20%.
[0040] The application will be further described in connection with specific examples. It should be understood that the examples are only used for illustrating the application and not used for limiting the scope of the application.
[0041] Example 1
[0042] 1.1, sequentially clean the single crystal aluminum sample with acetone, sodium hydroxide solution, anhydrous ethanol and nitric acid solution, polish treatment, and clean again to obtain a pretreated welding part; the mass fraction of the sodium hydroxide solution is 10%, and the volume fraction of the nitric acid solution is 15%.
[0043] 1.2, the ion selective etching treatment is performed on the welding surface of the pretreated welding part, and then the terpineol is coated to obtain an intermediate welding part; wherein the plasma gas used in the plasma selective etching treatment comprises CCl4 and O2, the molar ratio of CCl4 to O2 in the plasma gas is 1.2:1, the plasma selective etching treatment is performed under atmospheric pressure inductive coupled plasma under the protection of argon, the power of the plasma selective etching treatment is 100W, the temperature is 250℃, the time is 5min, the voltage is 450V, the beam current intensity is 100mA, and the argon flow rate is 20sccm.
[0044] 1.3, the terpineol on the surface of the intermediate welding part is washed away, the welding surfaces of two intermediate welding parts are overlapped and butted together, and the discharge plasma sintering treatment is performed to connect the intermediate welding parts together to obtain a single crystal aluminum welded joint; wherein the discharge plasma sintering treatment is performed in an SPS diffusion furnace, the temperature of the discharge plasma sintering treatment is 400℃, the pressure is 10MPa, and the time is 1h.
[0045] The single crystal aluminum welded joint obtained in example 1 is 95.1%.
[0046] Example 2
[0047] 2.1, sequentially clean the single crystal aluminum sample with acetone, sodium hydroxide solution, anhydrous ethanol and nitric acid solution, polish treatment, and clean again to obtain a pretreated welding part; the mass fraction of the sodium hydroxide solution is 10%, and the volume fraction of the nitric acid solution is 15%.
[0048] 2.2, the surface of the pre-welding part is treated by plasma selective etching, and then coated with ethylene glycol to obtain an intermediate welding part; wherein the plasma gas used in the plasma selective etching treatment includes CCl4 and O2, the molar ratio of CCl4 and O2 in the plasma gas is 1.3:1, the plasma selective etching treatment is carried out under the protection of argon by using atmospheric pressure inductively coupled plasma, the power of the plasma selective etching treatment is 150W, the temperature is 200℃, the time is 7min, the voltage is 400V, the beam current intensity is 80mA, and the argon flow rate is 25sccm.
[0049] 2.3, the ethylene glycol on the surface of the intermediate welding part is washed away, the surfaces of the two intermediate welding parts to be welded are overlapped and butted together, and then treated by discharge plasma sintering to connect the intermediate welding parts together to obtain a single crystal aluminum welding joint; wherein the discharge plasma sintering treatment is carried out in an SPS diffusion furnace, the temperature of the discharge plasma sintering treatment is 450℃, the pressure is 8MPa, and the time is 0.8h.
[0050] The single crystal aluminum welding joint obtained in Example 2 is 98.2%.
[0051] In addition, it should be noted that although the present application is disclosed as above, the protection scope of the present application is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present application, and these changes and modifications will fall within the protection scope of the present application.
Claims
1. A method of spark plasma sintering bonding of single crystal aluminum, characterized by, The application relates to a method for connecting single-crystal aluminum by using a discharge plasma sintering method. The method comprises the following steps: S1, performing surface cleaning treatment on a single-crystal aluminum sample to obtain a pretreated welding piece; S2, performing surface treatment on a welding surface of the pretreated welding piece to obtain an intermediate welding piece; the surface treatment comprises plasma selective etching treatment; the plasma gas used in the plasma selective etching treatment comprises a first gas and O2, wherein the first gas comprises at least one of CCl4 and CF4; the plasma selective etching treatment is performed under the protection of argon gas by using atmospheric pressure inductive coupling plasma, and the power of the plasma selective etching treatment is 50-200 W, the temperature is 200-300 DEG C, the time is 1-10 min, the voltage is 300-600 V, the beam current intensity is 50-200 mA, and the argon gas flow is 10-30 sccm; S3, superimposing and butting the welding surfaces of the intermediate welding pieces to each other to perform discharge plasma sintering treatment so as to connect the intermediate welding pieces to each other to obtain a single-crystal aluminum welding joint; the temperature of the discharge plasma sintering treatment is 350-500 DEG C, the pressure is 5-15 MPa, and the time is 0.5-1 h. In the step S2, the plasma gas comprises CCl4 and O2, and the molar ratio of CCl4 to O2 in the plasma gas is (1-1.3):
1. In the step S2, the plasma gas comprises CF4 and O2, and the molar ratio of CF4 to O2 in the plasma gas is (1-1.3):
1.
2. The method of connecting single crystal aluminum by spark plasma sintering according to claim 1, characterized in that, In the step S2, the surface treatment further comprises coating a protective liquid on the welding surface of the welding piece after the plasma selective etching treatment.
3. The method of connecting single crystal aluminum by spark plasma sintering according to claim 1, characterized in that, In the step S1, the surface cleaning treatment on the single-crystal aluminum sample comprises the following steps: sequentially cleaning the single-crystal aluminum sample with acetone, a sodium hydroxide solution, anhydrous ethanol and a nitric acid solution, polishing treatment, and cleaning again.
4. The method of connecting single crystal aluminum by spark plasma sintering according to claim 1, characterized in that, The mass fraction of the sodium hydroxide solution is 5-10%, and the volume fraction of the nitric acid solution is 12-20%.
5. The method of connecting single crystal aluminum by spark plasma sintering according to claim 1, wherein The single-crystal aluminum welding joint is prepared by using the method for connecting single-crystal aluminum by using a discharge plasma sintering method.
6. The method of connecting single crystal aluminum by spark plasma sintering according to claim 5, characterized in that, 7. A single crystal aluminum weld joint, characterized by,
Citation Information
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