Low temperature high strength aluminum brazing method of al2o3 ceramic to stainless steel
By depositing Al and Cu layers on the surfaces of Al2O3 ceramics and stainless steel and performing low-temperature brazing under vacuum conditions, the problem of high-strength connection between Al2O3 ceramics and stainless steel was solved, achieving a low-energy-consumption and high-strength connection effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI DIANJI UNIV
- Filing Date
- 2026-04-22
- Publication Date
- 2026-06-09
Abstract
Description
Technical Field
[0001] This invention relates to the field of dissimilar material joining technology, and in particular to a low-temperature, high-strength aluminum brazing method for Al2O3 ceramic and stainless steel. Background Technology
[0002] Alumina (Al2O3) ceramics possess high hardness, high insulation, good corrosion resistance, and high-temperature resistance, making them an ideal matching material for stainless steel. Combining Al2O3 ceramics with stainless steel leverages the electrical insulation and corrosion resistance of ceramics with the excellent mechanical properties and machinability of stainless steel, offering broad application prospects in aerospace, electronic packaging, medical equipment, and smart city sensors.
[0003] Brazing is one of the most commonly used techniques for joining Al2O3 ceramics and stainless steel. However, due to the significant difference in the coefficients of thermal expansion between Al2O3 ceramics and stainless steel (Al2O3 is approximately 8 × 10⁻⁶), the bonding process is not feasible. -6 / K, stainless steel is approximately 17×10 -6 Furthermore, ceramic surfaces are difficult to wet with ordinary brazing filler metals. Currently, the common methods to solve the wetting problem between the brazing filler metal and the ceramic are active brazing filler metal method, which involves adding active elements to the filler metal, or ceramic metal activation method, which involves coating an active layer on the ceramic surface. However, both of these methods achieve wetting through the reaction of active elements on the ceramic, inevitably producing a reaction layer. This reaction layer will adversely affect the mechanical properties, airtightness, and corrosion resistance of the brazed joint. In addition, traditional active brazing methods usually need to be performed at temperatures above 800 ℃. For example, when using Ag-Cu-Ti filler metal to connect Al2O3 ceramics and stainless steel, the brazing temperature is usually 850 ℃~900 ℃. High-temperature brazing is not only energy-intensive and inefficient, but it also easily leads to coarsening of the stainless steel structure, performance degradation, and thermal damage to heat-sensitive components. Moreover, the thermal expansion coefficients of Al2O3 ceramics and stainless steel differ significantly, and large residual thermal stress is easily generated during the cooling process after high-temperature brazing, leading to weld cracking or reduced joint strength, or even fracture of the ceramic base material.
[0004] In recent years, researchers have attempted to address these issues by lowering the brazing temperature. For example, adding melting-reducing elements such as In and Sn to Ag-Cu-Ti brazing filler metals yielded low-temperature brazing filler metals with brazing temperatures ranging from 620 ℃ to 640 ℃, but the joint strength was only 20.28 MPa. Another study used SnZn-based active brazing filler metals for ultrasonic brazing of ceramics and aluminum alloys at 270 ℃ to 300 ℃, achieving low-temperature connections, but this technique requires ultrasonic assistance and is only suitable for small-sized components. However, none of the above solutions can simultaneously meet the dual requirements of low-temperature brazing (≤700 ℃) and high strength (≥100 MPa).
[0005] Therefore, there is an urgent need in this field to develop a connection technology that can braze Al2O3 ceramics and stainless steel at temperatures below 700 °C and achieve high connection strength (greater than 100 MPa). Summary of the Invention
[0006] To address the problems of excessive reaction layer and high brazing temperature in traditional Al2O3 ceramic-stainless steel brazing methods, this invention aims to provide a low-temperature, high-strength aluminum brazing method for Al2O3 ceramics and stainless steel. This method uses aluminum and its alloy foils as brazing filler metals, achieving a direct, high-strength connection between Al2O3 ceramics and stainless steel at brazing temperatures below 700°C.
[0007] The objective of this invention can be achieved through the following technical solutions: This invention provides a low-temperature, high-strength aluminum brazing method for Al2O3 ceramics and stainless steel, comprising the following steps: (S1) An Al layer and a Cu layer are sequentially deposited on the surface of the pretreated Al2O3 ceramic component to be welded; An Al layer and a Cu layer are sequentially deposited on the pretreated stainless steel component surface to be welded. (S2) Place the Al foil brazing filler metal between the Al2O3 ceramic component to be welded surface treated in step (S1) and the stainless steel component to be welded surface to obtain an Al2O3 ceramic-brazing filler metal-stainless steel assembly; (S3) The Al2O3 ceramic-brazing filler metal-stainless steel assembly obtained in step (S2) is placed in a vacuum brazing furnace for brazing treatment. After the treatment, it is cooled to room temperature to obtain an Al2O3 ceramic-stainless steel brazed joint.
[0008] In one embodiment of the present invention, in step (S1), the pretreated Al2O3 ceramic component is specifically as follows: Polish and clean the surfaces of the Al2O3 ceramic components to be welded.
[0009] In one embodiment of the present invention, in step (S1), the pretreated stainless steel component is specifically as follows: Polish and clean the surfaces of stainless steel parts to be welded.
[0010] In one embodiment of the present invention, the cleaning is performed by ultrasonic cleaning with acetone for 10-15 minutes to remove surface oil and impurities.
[0011] In one embodiment of the present invention, in step (S1), the stainless steel is selected from 304 stainless steel, 316 stainless steel or 1Cr18Ni9Ti stainless steel.
[0012] In one embodiment of the present invention, in step (S1), the thickness of the Al layer is 0.1~2 μm; The thickness of the Cu layer is 50~500 nm.
[0013] In one embodiment of the present invention, in step (S2), the Al foil solder is pure Al foil or Al alloy foil.
[0014] In one embodiment of the present invention, in step (S2), during the brazing process, the vacuum level is higher than 5 × 10⁻⁶. -3 Pa, brazing temperature is 500~700 ℃, hold for 10~30 min.
[0015] In one embodiment of the present invention, in step (S3), during the brazing process, the brazing temperature is 660 °C and the holding time is 30 min.
[0016] In one embodiment of the present invention, in step (S3), the cooling rate during the cooling process is 5~10 °C / min.
[0017] In one embodiment of the present invention, in step (S3), the joint strength of the Al2O3 ceramic-stainless steel brazed joint is 60~115 MPa.
[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) Low brazing temperature: Compared with traditional Ag-Cu-Ti active brazing (850~900 ℃), the present invention reduces the brazing temperature to 500~700 ℃ (reduced by 150~400 ℃), which greatly reduces energy consumption and reduces thermal damage to stainless steel substrate and heat-sensitive components.
[0019] (2) High connection strength: The Al2O3 ceramic-stainless steel brazed joint prepared by the present invention has a room temperature shear strength of more than 100 MPa, and can reach up to 150 MPa, which far exceeds the strength level of existing low temperature brazing technology.
[0020] (3) Low residual thermal stress: Due to the low brazing temperature and the moderate thermal expansion coefficient of Al-based brazing filler metal, the residual thermal stress after welding is significantly reduced, and the joint is not prone to cracking.
[0021] (4) Environmentally friendly: The present invention uses Al-based solder that is free of Ag and Pb, avoiding the use of precious metals and toxic metals, which is in line with the development direction of green manufacturing. Detailed Implementation
[0022] The present invention will now be described in detail with reference to specific embodiments.
[0023] Unless otherwise specified, all reagents used in the following embodiments are commercially available reagents, and all detection methods and techniques used are conventional detection methods and techniques in the art.
[0024] Example 1 This embodiment provides a low-temperature, high-strength aluminum brazing method for Al2O3 ceramics and stainless steel, including the following steps: (S1) Polish and clean the surface of the Al2O3 ceramic component to be welded (use acetone for ultrasonic cleaning for 10 min to remove surface oil and impurities) to obtain the pretreated Al2O3 ceramic component. Polish and clean the surface of the stainless steel part (304 stainless steel) to be welded (use acetone for ultrasonic cleaning for 10 minutes to remove surface oil and impurities) to obtain the pretreated stainless steel part. (S2) Place the pretreated Al2O3 ceramic component obtained in step (S1) into the magnetron sputtering chamber, and achieve a back-bottom vacuum of 5 × 10⁻⁶. -4 After Pa, Ar with a purity of 99.999% is introduced and the pressure is maintained at 0.6 Pa. The Al2O3 ceramic component in the vacuum chamber is baked at 400 °C for 30 min to remove gaseous impurities adsorbed on the substrate surface. Then, a 1 μm thick Al film is first sputtered and deposited on the surface of the component to be soldered, followed by a 100 nm thick Cu film. The pretreated stainless steel part prepared in step (S1) is placed in the magnetron sputtering chamber, and the back vacuum of the vacuum chamber reaches 5 × 10⁻⁶. -4 After Pa, Ar with a purity of 99.999% is introduced and the pressure is maintained at 0.6 Pa. The stainless steel parts in the vacuum chamber are baked at 400 °C for 30 min to remove gaseous impurities adsorbed on the substrate surface. Then, a 1 μm thick Al film is first sputtered and deposited on the surface of the parts to be soldered, followed by a 100 nm thick Cu film. (S3) After step (S2) is completed, the Al2O3 ceramic component and the stainless steel component are removed, and the Al foil solder (pure Al foil) is placed between the surface of the Al2O3 ceramic component to be soldered and the surface of the stainless steel component to be soldered, to obtain the Al2O3 ceramic-solder-stainless steel assembly. (S4) Place the Al2O3 ceramic-brazing filler metal-stainless steel assembly obtained in step (S3) into a vacuum brazing furnace and evacuate to a vacuum level of not less than 5 × 10⁻⁶. -3 Pa; Under vacuum conditions, the assembly was heated to a brazing temperature of 600 ℃ and held for 30 min, and then cooled to room temperature at a cooling rate of 5 ℃ / min to obtain an Al2O3 ceramic-stainless steel brazed joint with a brazing strength of 60 MPa.
[0025] Example 2 This embodiment provides a low-temperature, high-strength aluminum brazing method for Al2O3 ceramics and stainless steel, including the following steps: (S1) Polish and clean the surface of the Al2O3 ceramic component to be welded (use acetone for ultrasonic cleaning for 10 min to remove surface oil and impurities) to obtain the pretreated Al2O3 ceramic component. Polish and clean the surface of the stainless steel part (304 stainless steel) to be welded (use acetone for ultrasonic cleaning for 10 minutes to remove surface oil and impurities) to obtain the pretreated stainless steel part. (S2) Place the pretreated Al2O3 ceramic component obtained in step (S1) into the magnetron sputtering chamber, and achieve a back-bottom vacuum of 5 × 10⁻⁶. -4 After Pa, Ar with a purity of 99.999% is introduced and the pressure is maintained at 0.6 Pa. The Al2O3 ceramic component in the vacuum chamber is baked at 400 °C for 30 min to remove gaseous impurities adsorbed on the substrate surface. Then, a 1 μm thick Al film is first sputtered and deposited on the surface of the component to be soldered, followed by a 100 nm thick Cu film. The pretreated stainless steel part prepared in step (S1) is placed in the magnetron sputtering chamber, and the back vacuum of the vacuum chamber reaches 5 × 10⁻⁶. -4 After Pa, Ar with a purity of 99.999% is introduced and the pressure is maintained at 0.6 Pa. The stainless steel parts in the vacuum chamber are baked at 400 °C for 30 min to remove gaseous impurities adsorbed on the substrate surface. Then, a 1 μm thick Al film is first sputtered and deposited on the surface of the parts to be soldered, followed by a 100 nm thick Cu film. (S3) After step (S2) is completed, the Al2O3 ceramic component and the stainless steel component are removed, and the Al foil solder (pure Al foil) is placed between the surface of the Al2O3 ceramic component to be soldered and the surface of the stainless steel component to be soldered, to obtain the Al2O3 ceramic-solder-stainless steel assembly. (S4) Place the Al2O3 ceramic-brazing filler metal-stainless steel assembly obtained in step (S3) into a vacuum brazing furnace and evacuate to a vacuum level of not less than 5 × 10⁻⁶. -3 Pa; Under vacuum conditions, the assembly was heated to the brazing temperature of 620 ℃, held for 30 min, and then cooled to room temperature at a cooling rate of 5 ℃ / min to obtain an Al2O3 ceramic-stainless steel brazed joint with a brazed joint strength of 82 MPa.
[0026] Example 3 This embodiment provides a low-temperature, high-strength aluminum brazing method for Al2O3 ceramics and stainless steel, including the following steps: (S1) Polish and clean the surface of the Al2O3 ceramic component to be welded (use acetone for ultrasonic cleaning for 10 min to remove surface oil and impurities) to obtain the pretreated Al2O3 ceramic component. Polish and clean the surface of the stainless steel part (304 stainless steel) to be welded (use acetone for ultrasonic cleaning for 10 minutes to remove surface oil and impurities) to obtain the pretreated stainless steel part. (S2) Place the pretreated Al2O3 ceramic component obtained in step (S1) into the magnetron sputtering chamber, and achieve a back-bottom vacuum of 5 × 10⁻⁶. -4 After Pa, Ar with a purity of 99.999% is introduced and the pressure is maintained at 0.6 Pa. The Al2O3 ceramic component in the vacuum chamber is baked at 400 °C for 30 min to remove gaseous impurities adsorbed on the substrate surface. Then, a 1 μm thick Al film is first sputtered and deposited on the surface of the component to be soldered, followed by a 100 nm thick Cu film. The pretreated stainless steel part prepared in step (S1) is placed in the magnetron sputtering chamber, and the back vacuum of the vacuum chamber reaches 5 × 10⁻⁶. -4 After Pa, Ar with a purity of 99.999% is introduced and the pressure is maintained at 0.6 Pa. The stainless steel parts in the vacuum chamber are baked at 400 °C for 30 min to remove gaseous impurities adsorbed on the substrate surface. Then, a 1 μm thick Al film is first sputtered and deposited on the surface of the parts to be soldered, followed by a 100 nm thick Cu film. (S3) After step (S2) is completed, the Al2O3 ceramic component and the stainless steel component are removed, and the Al foil solder (pure Al foil) is placed between the surface of the Al2O3 ceramic component to be soldered and the surface of the stainless steel component to be soldered, to obtain the Al2O3 ceramic-solder-stainless steel assembly. (S4) Place the Al2O3 ceramic-brazing filler metal-stainless steel assembly obtained in step (S3) into a vacuum brazing furnace and evacuate to a vacuum level of not less than 5 × 10⁻⁶. -3 Pa; Under vacuum conditions, the assembly was heated to the brazing temperature of 640 ℃, held for 30 min, and then cooled to room temperature at a cooling rate of 5 ℃ / min to obtain an Al2O3 ceramic-stainless steel brazed joint with a brazed joint strength of 98 MPa.
[0027] Example 4 This embodiment provides a low-temperature, high-strength aluminum brazing method for Al2O3 ceramics and stainless steel, including the following steps: (S1) Polish and clean the surface of the Al2O3 ceramic component to be welded (use acetone for ultrasonic cleaning for 10 min to remove surface oil and impurities) to obtain the pretreated Al2O3 ceramic component. Polish and clean the surface of the stainless steel part (304 stainless steel) to be welded (use acetone for ultrasonic cleaning for 10 minutes to remove surface oil and impurities) to obtain the pretreated stainless steel part. (S2) Place the pretreated Al2O3 ceramic component obtained in step (S1) into the magnetron sputtering chamber, and achieve a back-bottom vacuum of 5 × 10⁻⁶. -4 After Pa, Ar with a purity of 99.999% is introduced and the pressure is maintained at 0.6 Pa. The Al2O3 ceramic component in the vacuum chamber is baked at 400 °C for 30 min to remove gaseous impurities adsorbed on the substrate surface. Then, a 1 μm thick Al film is first sputtered and deposited on the surface of the component to be soldered, followed by a 100 nm thick Cu film. The pretreated stainless steel part prepared in step (S1) is placed in the magnetron sputtering chamber, and the back vacuum of the vacuum chamber reaches 5 × 10⁻⁶. -4 After Pa, Ar with a purity of 99.999% is introduced and the pressure is maintained at 0.6 Pa. The stainless steel parts in the vacuum chamber are baked at 400 °C for 30 min to remove gaseous impurities adsorbed on the substrate surface. Then, a 1 μm thick Al film is first sputtered and deposited on the surface of the parts to be soldered, followed by a 100 nm thick Cu film. (S3) After step (S2) is completed, the Al2O3 ceramic component and the stainless steel component are removed, and the Al foil solder (pure Al foil) is placed between the surface of the Al2O3 ceramic component to be soldered and the surface of the stainless steel component to be soldered, to obtain the Al2O3 ceramic-solder-stainless steel assembly. (S4) Place the Al2O3 ceramic-brazing filler metal-stainless steel assembly obtained in step (S3) into a vacuum brazing furnace and evacuate to a vacuum level of not less than 5 × 10⁻⁶. -3 Pa; Under vacuum conditions, the assembly was heated to the brazing temperature of 660 ℃ and held for 30 min, and then cooled to room temperature at a cooling rate of 5 ℃ / min to obtain an Al2O3 ceramic-stainless steel brazed joint with a brazed joint strength of 115 MPa.
[0028] Comparative Example 1 This comparative example is the same as Example 4 except that pure Al foil is not added.
[0029] The results showed that the brazed joints had low strength, and some could not even be welded. This was because the deposited Al and Cu layers were very thin. On the one hand, the weld area was very thin, making it difficult to coordinate the thermal stress between the Al2O3 ceramic component and the stainless steel component. On the other hand, the solder could not completely fill the weld area after melting, and voids were prone to appear in local areas.
[0030] Comparative Example 2 This comparative example is the same as Example 4 except that the brazing temperature is 490 °C.
[0031] The results showed that the brazed joint had low strength. This was due to the low brazing temperature, which led to the formation of intermetallic compounds and eutectic structures in the weld, resulting in greater brittleness of the brazed joint.
[0032] Comparative Example 3 This comparative example is the same as Example 4 except that the brazing temperature is 900 °C.
[0033] The results showed that, on the one hand, the high brazing temperature resulted in significant thermal stress between the Al2O3 ceramic and stainless steel components, leading to low brazing joint strength; on the other hand, the high temperature altered the microstructure of the stainless steel, resulting in reduced performance.
[0034] When the brazing temperature is 500~600 ℃, the Al foil brazing filler metal is selected from aluminum alloy foil.
[0035] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the interpretation of the present invention, without departing from the scope of the invention, should be within the protection scope of the present invention.
Claims
1. A low-temperature, high-strength aluminum brazing method for Al2O3 ceramics and stainless steel, characterized in that, Includes the following steps: (S1) An Al layer and a Cu layer are sequentially deposited on the surface of the pretreated Al2O3 ceramic component to be welded; An Al layer and a Cu layer are sequentially deposited on the pretreated stainless steel component surface to be welded. (S2) Place the Al foil brazing filler metal between the Al2O3 ceramic component to be welded surface treated in step (S1) and the stainless steel component to be welded surface to obtain an Al2O3 ceramic-brazing filler metal-stainless steel assembly; (S3) The Al2O3 ceramic-brazing filler metal-stainless steel assembly obtained in step (S2) is placed in a vacuum brazing furnace for brazing treatment. After the treatment, it is cooled to room temperature to obtain an Al2O3 ceramic-stainless steel brazed joint.
2. The method for low-temperature high-strength aluminum brazing of Al2O3 ceramic and stainless steel according to claim 1, characterized in that, In step (S1), the pretreated Al2O3 ceramic components are as follows: Polish and clean the surfaces of the Al2O3 ceramic components to be welded.
3. The method for low-temperature high-strength aluminum brazing of Al2O3 ceramic and stainless steel according to claim 1, characterized in that, In step (S1), the pre-treated stainless steel parts are as follows: Polish and clean the surfaces of stainless steel parts to be welded.
4. The low-temperature high-strength aluminum brazing method for Al2O3 ceramic and stainless steel according to claim 1, characterized in that, In step (S1), the stainless steel is selected from one of 304 stainless steel, 316 stainless steel or 1Cr18Ni9Ti stainless steel.
5. The method for low-temperature high-strength aluminum brazing of Al2O3 ceramic and stainless steel according to claim 1, characterized in that, In step (S1), the thickness of the Al layer is 0.1~2 μm; The thickness of the Cu layer is 50~500 nm.
6. The method for low-temperature high-strength aluminum brazing of Al2O3 ceramic and stainless steel according to claim 1, characterized in that, In step (S2), the Al foil brazing filler metal is pure Al foil or Al alloy foil.
7. The method for low-temperature high-strength aluminum brazing of Al2O3 ceramic and stainless steel according to claim 1, characterized in that, In step (S2), during the brazing process, the vacuum level is higher than 5×10⁻⁶. -3 Pa, brazing temperature is 500~700 ℃, hold for 10~30 min.
8. The method for low-temperature high-strength aluminum brazing of Al2O3 ceramic and stainless steel according to claim 1, characterized in that, In step (S3), during the brazing process, the brazing temperature is 660 ℃ and the holding time is 30 min.
9. A method for low-temperature high-strength aluminum brazing of Al2O3 ceramic and stainless steel according to claim 1, characterized in that, In step (S3), the cooling rate is 5~10 ℃ / min during the cooling process.
10. A method for low-temperature high-strength aluminum brazing of Al2O3 ceramic and stainless steel according to claim 1, characterized in that, In step (S3), the joint strength of the Al2O3 ceramic-stainless steel brazed joint is 60~115MPa.