A method for heterogeneous connection between ceramic and metal
By constructing multiple layers of metallization and intermediate buffer layers on the surfaces of ceramics and metals, the stress problem caused by the difference in thermal expansion coefficient and composition inhomogeneity between ceramics and metals during high-temperature brazing is solved, and the stability and sealing of the ceramic-metal connection at high temperatures are achieved.
Patent Information
- Application Number
- CN202411894047.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-20
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2044-12-20
AI Technical Summary
During the high-temperature brazing process, differences in thermal expansion coefficients and compositional inhomogeneities between ceramic and metal materials cause stress at the joints, affecting sealing and connection strength. Furthermore, the brazing filler metal is unevenly distributed, making it difficult to form a continuous and dense brazing layer.
A multi-layer metallization layer is constructed on the surface of ceramic and metal, and a metal intermediate buffer layer is added before brazing. A uniform brazing layer is formed through high-temperature sintering and vacuum brazing, combined with a protective layer to improve interface sealing and mechanical connection strength.
It effectively absorbs thermal stress, reduces wettability differences, forms a uniform and continuous brazing layer, improves the sealing and mechanical connection strength of the brazing interface, and enhances service life in harsh environments.
Smart Images
Figure CN119430983B_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the application field of ceramic-metal connection, and in particular to a method for heterogeneous connection of ceramic and metal. Background Art
[0002] Ceramic materials have excellent properties such as high insulation, high temperature resistance, corrosion resistance, oxidation resistance, high hardness, high strength, and wear resistance, but their plasticity, toughness, and ductility are extremely poor. Once the force exceeds the elastic strain limit (the strain is very small), they will quickly break. Metal materials have excellent mechanical properties such as conductivity, plasticity, toughness, ductility, and weldability, but under harsh working conditions, such as high temperatures above 700°C, the strength and chemical stability of metal materials decrease rapidly. Therefore, in applications with harsh working conditions such as aviation, military, nuclear energy, chemical industry, and machinery, it is the industry's unified understanding and practice to use the advantages of the two types of materials in a complementary manner (i.e., ceramic-metal connectors), which is also one of their core technologies. Ceramic-metal brazing, as a method of connecting ceramics and metals, has the advantages of high connection strength, good sealing, high high-temperature chemical stability, simple operation, high welding yield, and good uniformity. It is the mainstream solution for high-strength, high-wear-resistant, and high-temperature service parts in aviation, military, nuclear energy, and chemical industry.
[0003] There are great differences in the physical and chemical properties of ceramics and metal materials. First, the thermal expansion coefficients of ceramics and metal materials are usually quite different. During the high-temperature brazing process, huge stress will be generated at the joints, resulting in a rapid decline in the sealing, connection strength and other properties of the ceramic-metal connector. Second, there are great differences in the internal composition and near-surface chemical properties of ceramics and metal materials. During the high-temperature brazing process, the degree of wetting of the brazing material on the ceramic and metal surfaces will be different, which can easily cause uneven distribution of the brazing material and the inability to form a continuous, dense, non-porous brazing layer. In addition, during the high-temperature brazing process, the molten brazing material will diffuse elements and combine with metals and ceramics to form compounds. However, due to the large difference and complexity of the composition near the surface of ceramics and metal materials, the inconsistency of the element diffusion degree and path of the brazing material will lead to uneven composition and distribution of the compounds formed on the ceramic and metal surfaces. Summary of the Invention
[0004] The object of the present invention is to provide a method for heterogeneous connection between ceramic and metal, which can avoid the generation of cracks at the brazing interface and improve the sealing performance and mechanical connection strength of the brazing interface.
[0005] To achieve the above object, the present invention provides the following technical solutions:
[0006] A method for heterogeneous connection between ceramic and metal, comprising the following steps:
[0007] Step 1: Covering the metal surface with a metal plating layer;
[0008] Step 2: Use tungsten slurry, pure molybdenum powder or molybdenum-manganese composite powder to form a primary metallization layer on the surface of the ceramic to be brazed by high-temperature sintering;
[0009] Step 3: Forming a nickel layer, nickel-phosphorus layer, or nickel-boron layer with a thickness of less than 20 μm on the surface of the primary metallization layer by electroplating, vapor deposition, chemical plating, or sintering, which is referred to as the secondary metallization layer;
[0010] Step 4: Attaching a tertiary metallization layer on the surface of the secondary metallization layer by electroplating. The main component of the tertiary metallization layer is pure copper, pure nickel, pure silver, pure gold, pure aluminum, copper-gold alloy, nickel-silver alloy or nickel-gold alloy. The thickness of the tertiary metallization layer is 20 μm-100 μm.
[0011] Step 5: Degreasing and decontamination the metal and ceramic, drying and cooling them, applying a certain amount of solder on the surface of the tertiary metallization layer to form a ceramic side solder layer, and applying a certain amount of solder on the surface of the metal plating layer to form a metal side solder layer;
[0012] Step 6: Assemble the metal and the ceramic, and place a metal intermediate buffer layer structure in the gap between the ceramic side solder layer and the metal side solder layer, so that the ceramic side solder layer and the metal side solder layer together clamp the metal intermediate buffer layer structure to form a metal-ceramic assembly, wherein the main body of the metal intermediate buffer layer structure is pure nickel, pure copper, pure silver or pure aluminum, and the surface of the main body is attached with a plating layer with the same composition as the three metallization layers, and the metal intermediate buffer layer structure is a sheet, mesh or porous structure;
[0013] Step 7: Place the metal-ceramic assembly into a brazing furnace, evacuate the furnace, then heat it to 400-500°C and keep it for 15-20 minutes, then heat it to 1100-1200°C and keep it for 5-10 minutes, and finally cool it down to room temperature.
[0014] Specifically, the metal is a 310S stainless steel tube, the ceramic is an alumina ceramic tube, a countersunk hole is opened at the end of the 310S stainless steel tube, and the alumina ceramic tube is matched with the countersunk hole.
[0015] Specifically, the solder is BNi5, and the metal plating layer is pure nickel.
[0016] Specifically, in step 2, the high temperature sintering temperature is 1300°C-1800°C.
[0017] Specifically, in step seven, the brazing furnace is evacuated to a vacuum degree of 10 -4 -10 -5 pa.
[0018] Specifically, in step seven, the temperature is increased to 450° C. at a heating rate of 5° C. / min and kept at this temperature for 15-20 minutes, and then the temperature is increased to 1150° C. and kept at this temperature for 5-10 minutes.
[0019] Specifically, after completing step seven, a protective layer is formed on the exposed surface of the brazing seam by spraying, brushing or brazing.
[0020] Specifically, the protective layer is glass glue, ceramic glue or active solder.
[0021] Compared with the prior art, the present invention has the following beneficial effects:
[0022] First, this method can form a ceramic surface buffer layer (tertiary metallization layer) and an intermediate buffer layer (metal intermediate buffer layer structure). The combination of the two in different spaces and layers can effectively absorb the thermal stress generated by the difference in thermal expansion coefficients between ceramics and metals during brazing, thereby avoiding the formation of cracks at the brazing interface.
[0023] Second, by constructing a layer of the same coating (pure nickel in this embodiment) on the surface of the ceramic, metal, and intermediate buffer layer (metal intermediate buffer layer structure), the ceramic, metal, and intermediate buffer layer (metal intermediate buffer layer structure) have the same composition and interface chemical properties, thereby reducing the difference in wettability of the solder on each component and the difference in the degree of diffusion of the solder elements into the interior of each component, which helps to form a uniform, continuous, and non-porous brazing layer (ceramic side brazing layer and metal side brazing layer) between the surfaces of the ceramic, metal, and intermediate buffer layer (metal intermediate buffer layer structure) to improve the sealing and mechanical connection strength of the brazing interface. In addition, the coating is similar in composition to the solder and has good interface compatibility with the solder, which can effectively guide the uniform fluidity of the solder in the molten state, and plays an important role in the construction of a non-porous brazing layer.
[0024] 3. Build a protective layer at the brazing joint of the brazed metal-ceramic assembly. The protective layer can be made of glass glue, ceramic glue, or active solder. The protective layer can prevent the molybdenum-manganese layer or solder layer at the brazing joint from being corroded by oxygen, water vapor, or other special gases in harsh operating environments over a long period of time, thereby extending the service life of the ceramic-metal assembly. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.
[0026] Figure 1This is a view before the stainless steel tube and the alumina ceramic tube are combined;
[0027] Figure 2 This is a view of the stainless steel tube and the alumina ceramic tube combined;
[0028] Figure 3 Schematic diagram of the structure of each layer at the brazing point.
[0029] In the picture:
[0030] 1. Ceramic; 2. Primary metallization layer; 3. Secondary metallization layer; 4. Tertiary metallization layer; 5. Ceramic side solder layer; 6. Metal intermediate buffer layer structure; 7. Metal side solder layer; 8. Metal plating layer; 9. Metal; 10. Protective layer. DETAILED DESCRIPTION
[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.
[0032] See Figure 1 In this embodiment, metal 9 is a 310S stainless steel tube, and ceramic 1 is an alumina ceramic tube. The 310S stainless steel tube has a countersunk hole at its end, into which the alumina ceramic tube fits. Alternatively, metal 9 can be made of Kovar alloy, nickel-based high-temperature alloy, or the like; ceramic 1 can be made of silicon carbide ceramic, zirconia ceramic, or the like.
[0033] The method for heterogeneous connection between ceramic and metal in this embodiment includes the following steps:
[0034] Step 1: Plate a metal coating 8 on the surface of the metal 9. In this embodiment, BNi5 is selected as the solder. BNi5 contains more than 70% nickel, so the metal coating 8 is pure nickel, and the melting point of pure nickel is not lower than that of the solder BNi5.
[0035] Step 2: Using tungsten slurry, pure molybdenum powder, or a molybdenum-manganese composite powder, a primary metallization layer 2 is formed on the surface of the ceramic 1 to be brazed by high-temperature sintering. The primary metallization layer 2 interpenetrates the surface of the ceramic 1 to be brazed, improving its adhesion. The formation of the primary metallization layer 2 alters the chemical properties of the ceramic 1 surface, transforming it from a non-metallic surface to a metallic one.
[0036] Step 3: A nickel layer, nickel-phosphorus layer, or nickel-boron layer with a thickness of less than 20 μm is formed on the surface of the primary metallization layer 2 by electroplating, vapor deposition, chemical plating, or sintering. This secondary metallization layer 3 protects the primary metallization layer 2 from corrosion by the brazing filler metal during subsequent brazing and improves wettability and bonding strength with the brazing filler metal.
[0037] Step 4: A tertiary metallization layer 4 is attached to the surface of the secondary metallization layer 3 by electroplating. The main components of the tertiary metallization layer 4 are pure copper, pure nickel, pure silver, pure gold, pure aluminum, copper-gold alloy, nickel-silver alloy or nickel-gold alloy. The main component of the tertiary metallization layer 4 is determined according to the main component of the solder selected subsequently. In this embodiment, BNi5 is selected as the solder, so the main component of the tertiary metallization layer 4 is pure nickel. The tertiary metallization layer 4 constructs a metal layer (pure nickel) on the surface of the secondary metallization layer 3 with a composition similar to that of the solder (BNi5) and a melting point not lower than that of the solder, so as to improve the compatibility with the solder during the subsequent brazing process and the consistency of the brazing interface properties, thereby helping to form a uniform and dense brazing layer.
[0038] The tertiary metallization layer 4 has a certain thickness, which is between 20-100 μm. Its purpose is to construct an elastic buffer layer on the surface of the ceramic 1 to absorb the thermal stress generated during the brazing process, slow down the generation of thermal cracks on the ceramic 1 interface and improve the mechanical stability of the ceramic 1 interface.
[0039] Step 5: Degrease and decontaminate the metal 9 and the ceramic 1, dry and cool them, and then apply a certain amount of BNi5 solder on the surface of the tertiary metallization layer 4 (in this embodiment, the tertiary metallization layer 4 is pure nickel) to form a ceramic side solder layer 5, and apply a certain amount of solder on the surface of the metal plating layer 8 (in this embodiment, the metal plating layer 8 is pure nickel) to form a metal side solder layer 7.
[0040] Step 6: Assemble the metal 9 and the ceramic 1, and place a metal intermediate buffer layer structure 6 in the gap between the ceramic side solder layer 5 and the metal side solder layer 7 (refer to Figure 3 ), so that the ceramic side brazing material layer 5 and the metal side brazing material layer 7 together clamp the metal intermediate buffer layer structure 6 to form a metal-ceramic assembly (such as Figure 2 (As shown). In this embodiment, the main body of the metal intermediate buffer layer structure 6 is pure nickel. As an alternative embodiment, the main body of the metal intermediate buffer layer structure 6 can be pure copper, pure silver, or pure aluminum. The surface of this main body is coated with a coating with the same composition as the tertiary metallization layer 4. The metal intermediate buffer layer structure 6 has a sheet, mesh, or porous structure.
[0041] The metal intermediate buffer layer structure 6 having a certain thickness serves as a buffer layer. By spatially cooperating with the tertiary metallization layer 4 which also serves as a buffer layer, it can absorb thermal stress during the subsequent brazing process and improve the stability of the brazing interface.
[0042] Step 7: Place the metal-ceramic assembly into a brazing furnace, evacuate the furnace, then heat it to 400-500°C and keep it for 15-20 minutes, then heat it to 1100-1200°C and keep it for 5-10 minutes, and finally cool it down to room temperature.
[0043] Step 8: See Figure 3 A protective layer 10 is formed on the exposed surface of the brazing joint by spraying, brushing, or brazing. Protective layer 10 can be made of glass glue, ceramic glue, or active solder. Protective layer 10 protects the molybdenum-manganese layer or solder layer at the brazing joint from long-term corrosion by oxygen, moisture, or other special gases in harsh operating environments, thereby extending the service life of the ceramic-metal assembly.
[0044] Specifically, in step 2, the high temperature sintering temperature is 1300°C-1800°C.
[0045] Specifically, in step seven, the brazing furnace is evacuated to a vacuum degree of 10 -4 -10 -5 pa.
[0046] Specifically, in step seven, the temperature is increased to 450° C. at a heating rate of 5° C. / min and kept at this temperature for 15-20 minutes, and then the temperature is increased to 1150° C. and kept at this temperature for 5-10 minutes.
[0047] Alternatively, the brazing material may be silver-based, copper-based, aluminum-based, or gold-based, in the form of paste, foil, or wire. It is used as a connecting material to connect ceramics and metal base materials via vacuum brazing or atmosphere brazing.
[0048] Correspondingly, the metal plating layer 8 can be pure copper, pure nickel, pure silver, pure gold, pure aluminum, etc. Its specific composition is determined according to the composition of the solder. Its purpose is to construct a metal layer on the surface of the metal 9 with a composition similar to that of the solder to improve the interface compatibility with the solder.
[0049] The beneficial effects of the present invention are as follows:
[0050] First, this method can form a ceramic surface buffer layer (tertiary metallization layer 4) and an intermediate buffer layer (metal intermediate buffer layer structure 6). The cooperation of the two at different spaces and levels can effectively absorb the thermal stress generated by the difference in thermal expansion coefficients during the brazing process between the ceramic 1 and the metal 9, thereby avoiding the formation of cracks at the brazing interface;
[0051] Second, by constructing a layer of the same coating (pure nickel in this embodiment) on the surface of the ceramic 1, the surface of the metal 9, and the surface of the intermediate buffer layer (metal intermediate buffer layer structure 6), the ceramic 1 surface, the metal 9 surface, and the intermediate buffer layer (metal intermediate buffer layer structure 6) have the same composition and interface chemical properties, thereby reducing the difference in wettability of the solder on each component and the difference in the degree of diffusion of the solder elements into the interior of each component, which helps to form a uniform, continuous, and non-porous brazing layer (ceramic side brazing layer 5 and metal side brazing layer 7) between the surfaces of the ceramic 1, metal 9, and the intermediate buffer layer (metal intermediate buffer layer structure 6), thereby improving the sealing and mechanical connection strength of the brazing interface. In addition, the coating has a similar composition to the solder and has good interface compatibility with the solder, which can effectively guide the uniform fluidity of the solder in the molten state, playing an important role in the construction of a non-porous brazing layer.
[0052] Third, a protective layer 10 is constructed at the brazing joint of the brazed metal-ceramic assembly. The protective layer 10 can be made of glass glue, ceramic glue, or active solder. This layer can protect the molybdenum-manganese layer or solder layer at the brazing joint from long-term corrosion by oxygen, moisture, or other special gases in harsh operating environments, thereby extending the service life of the ceramic-metal assembly.
[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention in any form. Although the present invention has been disclosed as above in terms of preferred embodiments, they are not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A method for heterogeneous connection between ceramic and metal, characterized in that: The following steps are involved: Step 1: Cover the metal surface with a metal plating layer. The metal is a 310S stainless steel tube, and the ceramic is an alumina ceramic tube. A countersunk hole is opened at the end of the 310S stainless steel tube, and the alumina ceramic tube is matched with the countersunk hole. Step 2: Use tungsten slurry, pure molybdenum powder or molybdenum-manganese composite powder to form a primary metallization layer on the surface of the ceramic to be brazed by high-temperature sintering; Step 3: Forming a nickel layer, nickel-phosphorus layer, or nickel-boron layer with a thickness of less than 20 μm on the surface of the primary metallization layer by electroplating, vapor deposition, chemical plating, or sintering, which is referred to as the secondary metallization layer; Step 4: Attaching a tertiary metallization layer on the surface of the secondary metallization layer by electroplating. The main component of the tertiary metallization layer is pure copper, pure nickel, pure silver, pure gold, pure aluminum, copper-gold alloy, nickel-silver alloy or nickel-gold alloy. The thickness of the tertiary metallization layer is 20 μm-100 μm. Step 5: Degreasing and decontamination the metal and ceramic, drying and cooling them, applying a certain amount of solder on the surface of the tertiary metallization layer to form a ceramic side solder layer, and applying a certain amount of solder on the surface of the metal plating layer to form a metal side solder layer; Step 6: Assemble the metal and the ceramic, and place a metal intermediate buffer layer structure in the gap between the ceramic side solder layer and the metal side solder layer, so that the ceramic side solder layer and the metal side solder layer together clamp the metal intermediate buffer layer structure to form a metal-ceramic assembly, wherein the main body of the metal intermediate buffer layer structure is pure nickel, pure copper, pure silver or pure aluminum, and the surface of the main body is attached with a plating layer with the same composition as the three metallization layers, and the metal intermediate buffer layer structure is a sheet, mesh or porous structure; Step 7: Place the metal-ceramic assembly into a brazing furnace, evacuate the furnace, then heat it to 400-500°C and keep it warm for 15-20 minutes, then heat it to 1100-1200°C and keep it warm for 5-10 minutes, and finally cool it down to room temperature with the furnace. A protective layer is formed on the exposed surface of the brazing seam by spraying, brushing or brazing. The protective layer is made of glass glue, ceramic glue or active solder.
2. The method for heterogeneous joining of ceramic and metal according to claim 1, characterized in that: The brazing filler metal is BNi5 and the metal plating layer is pure nickel.
3. The method for heterogeneous joining of ceramic and metal according to claim 1, characterized in that: In step 2, the high temperature sintering temperature is 1300°C-1800°C.
4. The method for heterogeneous joining of ceramic and metal according to claim 1, characterized in that: In step 7, the brazing furnace is evacuated to a vacuum degree of 10 -4 -10 -5 pa.
5. The method for heterogeneous joining of ceramic and metal according to claim 1, characterized in that: In step seven, the temperature is increased to 450°C at a heating rate of 5°C / min and kept at this temperature for 15-20 min, and then the temperature is increased to 1150°C and kept at this temperature for 5-10 min.