YSZ ceramic and aluminum-silicon alloy low-temperature connection glass soldering paste and connection method

Abstract

The invention discloses a YSZ ceramic and aluminum-silicon alloy low-temperature connection glass soldering paste and a connection method, the low-temperature connection glass soldering paste is prepared by mixing bismuthate glass powder and an organic carrier, and the mass ratio of the bismuthate glass powder to the organic carrier is (6-8): 1; wherein the bismuthate glass powder is prepared from the following raw materials in percentage by mass: 75 to 80 percent of Bi2O3, 10 to 15 percent of B2O3, 6 to 8 percent of SiO2 and 2 to 4 percent of CuO. Compared with the prior art, the bismuthate glass powder has excellent thermal stability and lower crystallization tendency during heating, so that the residual stress of a weld joint is reduced, the joint strength is improved, and the low-temperature connection process is simple, does not need metallization pretreatment, and is low in welding temperature, low in cost and environmentally friendly.

Description

TECHNICAL FIELD

[0001] The application relates to a low-temperature connecting glass solder paste for YSZ ceramic and aluminum-silicon alloy and a connecting method, and belongs to the technical field of dissimilar material connection. BACKGROUND

[0002] YSZ (Y2O3 reinforced ZrO2) ceramic is a high-performance ceramic with excellent mechanical properties, excellent high-temperature resistance, corrosion resistance and other advantages, and is widely used in aerospace, electronic engineering and medical care fields. Aluminum-silicon alloy has been widely used in the fields of automobile manufacturing and electronic packaging due to its light weight, high strength, and strong heat dissipation capacity. At present, the connecting piece of YSZ ceramic and aluminum-silicon alloy has been widely used in the fields of electronic packaging and semiconductor, for example, the IGBT heat dissipation substrate of new energy vehicles is a connecting piece with ceramic as the substrate and aluminum-silicon alloy as the heat dissipation layer. The composite connecting piece of YSZ ceramic and aluminum-silicon alloy is a key component for realizing the integration of "insulation-heat dissipation" function, and the connection reliability directly determines the service life and operation safety of the IGBT module.

[0003] However, in actual application, the connection of ceramic and metal, especially aluminum-based alloy, faces several common problems: on the one hand, the surface of ceramic is usually an oxide, which is chemically inert and has low surface energy, and is difficult to be wetted by most metal melts or solders; on the other hand, the thermal expansion coefficients of ceramic and aluminum alloy are quite different, and thermal stress concentration is easily generated during high-temperature brazing or welding, resulting in interface cracks, peeling or substrate damage.

[0004] In order to overcome the above problems, the existing technology mainly adopts the following solutions: 1. Metallization of ceramic or metal surface to improve wettability The most widely used method is to first perform pre-metallization treatment on the ceramic surface to be connected with the metal to form a metal film, so as to improve the wettability of the metal solder and realize the matching of the thermal expansion coefficients, and then realize reliable connection of the metal and the ceramic through metal brazing.

[0005] For example, Chinese patent CN118344170B provides a low-temperature connecting method for silicon carbide ceramic and heat dissipation copper plate, which performs metallization treatment on the surface of the pre-cleaned silicon carbide ceramic through magnetron sputtering technology, and short-time heat preservation at low temperature for the welding part, thereby realizing low-temperature connection of ceramic and metal. However, the metallization process in this method increases the welding cost and reduces the production efficiency.

[0006] 2. Glass / metal solder welding, if necessary, under vacuum or protective atmosphere to avoid oxidation Chinese patent CN113666766B proposes the infiltration connection of glass solder and YSZ ceramic, and a reliable YSZ ceramic joint is obtained by holding at more than 1300℃. However, the welding temperature of this method is already much higher than the melting point of aluminum-silicon alloy, which is not suitable for the connection of YSZ ceramic and aluminum-silicon alloy; in addition, Chinese patent application CN119897627A designs a metal solder mixed with copper powder and tin-bismuth solder powder, and realizes the low-temperature welding of ceramic and metal below 200℃ in a vacuum environment. However, this method has high requirements for the welding environment and cannot realize the welding of YSZ ceramic and aluminum-silicon alloy in a conventional atmospheric environment, and the welding production cost is high, which is difficult to scale up.

[0007] In view of the above status, it is of significant engineering and industrial value to develop a connection process for YSZ-aluminum-silicon alloy at a relatively low temperature without metalizing pretreatment in an atmospheric environment. SUMMARY

[0008] In order to solve the above problems, a low-temperature connection glass solder paste for YSZ ceramic and aluminum-silicon alloy and a connection method are provided, which can realize reliable low-temperature (≤500℃) welding in an atmospheric environment by optimizing the formula of the glass solder and matching the segmented soldering process, and the welded joint has high room temperature shear strength, which can meet the actual use requirements.

[0009] The core characteristics of YSZ ceramic are ionic crystal structure, high surface energy, strong chemical inertness (acid and alkali resistant, difficult to react with conventional substances), and low thermal expansion coefficient. These characteristics make it difficult for conventional solders (such as metal solder and ordinary glass solder) to form a reliable interface bond, and the thermal expansion mismatch may cause cracking.

[0010] The core characteristics of aluminum-silicon alloy (taking Al50Si as an example) are metal crystal structure, easy oxidation at high temperature, and low melting point (solidus about 577℃, which will deform and melt when the temperature exceeds it). These characteristics make it impossible to use conventional high-temperature solders, and the oxidation layer will block the bonding between the solder and the substrate.

[0011] The present application effectively reduces the influence of the difference in thermal expansion coefficient between the two substrates by specifically designing the formula of the glass solder paste and the welding process, realizes stable welding at low temperature, and solves the contradictions of the characteristics of the two substrates through the synergy of the four components, and finally realizes reliable connection.

[0012] According to one aspect of the present application, a low-temperature connection glass solder paste for YSZ ceramic and aluminum-silicon alloy is provided, which is prepared by mixing bismuthate glass powder and organic carrier, and the mass ratio of bismuthate glass powder to organic carrier is (6-8):1; According to the present application, the bismuthate glass powder includes the following raw materials in terms of mass percentage: Bi2O375~80%, B2O310~15%, SiO26~8%, and CuO 2~4%.

[0013] Specifically, the glass solder paste of the present application simultaneously adds specific proportions of SiO2 and CuO, SiO2 is the basis of forming a glass phase in the glass solder paste system, and forms an irregular network structure of SiO4 (silicon-oxygen tetrahedron) glass phase. This network structure is the skeleton of the glass system to form glass, and the increase of the network polymerization degree can inhibit the formation of crystal nucleus, significantly reduce the crystallization tendency, and improve the joint performance. However, the inventors found that the addition of SiO2 can increase the softening temperature of the glass system and the viscosity in the wetting and spreading process (SiO4 network hinders molecular flow), and also increase the energy consumption in the melting process of the glass system.

[0014] To this end, the inventors add CuO to balance the soldering performance of the system. Cu 2+ As a network modifier, it can moderately break the dense network of SiO2, partially destroy the silicon-oxygen skeleton, and reduce the melt viscosity, so as to obtain better spreading and wetting of the substrate surface at a lower temperature (which is conducive to low-temperature brazing). At the same time, by adding an appropriate amount of CuO, the thermal expansion characteristics of the glass phase can be changed, the difference in the thermal expansion coefficient between YSZ / aluminum-silicon alloy can be reduced, and thus the thermal stress after cooling can be reduced, and the interface crack can be reduced. And CuO can synergistically act with SiO2, CuO can help to reduce the adverse crystallization, thereby improving the joint density and mechanical strength.

[0015] Further, by limiting the mass ratio of bismuthate glass powder and organic carrier, the flowability and degassing behavior of the solder paste are controlled. The powder / body ratio directly affects the flowability, gap filling ability and porosity left after the volatilization of the organic matter of the solder paste during the heating process. Limiting the ratio range can make the solder neither flow excessively nor have insufficient wetting. The best strength is obtained within the process window, and finally a dense and continuous glass layer is formed, thereby improving the mechanical properties of the joint.

[0016] Optionally, the mass ratio of Bi2O3 to B2O3 in the bismuthate glass powder is (5.5-8):1.

[0017] Specifically, by further limiting the mass ratio of Bi2O3 to B2O3 in the bismuthate glass powder, Bi2O3 is an oxide with high refractive index and low migration energy, which can significantly reduce the softening point of the glass and improve the wetting property. B2O3 acts as a glass network forming aid, and by controlling the ratio of the two, a balance between low temperature flowability and low crystallization tendency can be achieved. A higher proportion of Bi2O3 can enhance the thermal stability of the glass phase and reduce the crystallization defects during soldering.

[0018] Optionally, the mass ratio of SiO2 to CuO in the bismuthate glass powder is (6-7):(3-4).

[0019] Specifically, within a defined SiO2 / CuO ratio range, it can maintain the stability of the glass network while achieving good fluidity at low temperatures, thus balancing wettability and anti-crystallization ability.

[0020] Optionally, the organic carrier comprises terpineol, ethyl cellulose, ethyl acetate, 1,2-propanediol, and soybean lecithin, in a mass ratio of (60-62):(10-12):(13-15):(7.5-8):(7.5-8). Preferably, the mass ratio is 60:10:15:7.5:7.5.

[0021] In this application, terpineol serves as the main solvent, ensuring the dispersibility of the glass powder; ethyl cellulose acts as a thickener, preventing sagging after solder paste application; ethyl acetate acts as a co-solvent, reducing system viscosity and improving coating smoothness; 1,2-propanediol acts as a humectant, preventing the solder paste from drying rapidly in air; and soybean lecithin acts as a surfactant, reducing the contact angle between the solder and the base material. This ensures that the glass solder paste applied in this application does not sagging or dry out, and completely evaporates after preheating.

[0022] Optionally, the particle size of the bismuthate glass powder is 10~20μm.

[0023] Optionally, the preparation method involves mixing Bi2O3, B2O3, SiO2 and CuO powders in a certain proportion, heating and holding the mixture, water quenching, and grinding to obtain the bismuthate glass powder.

[0024] Optionally, the heating temperature is 1150-1170℃, the holding time is 60 minutes, and the material is then ground and sieved through a 1200-mesh sieve.

[0025] According to one aspect of this application, a low-temperature bonding method for YSZ ceramic and aluminum-silicon alloy is provided, using the aforementioned low-temperature bonding glass solder paste, comprising the following steps: (1) Grind, clean and dry the aluminum-silicon alloy surfaces to be welded; (2) The surface of YSZ ceramic to be welded is mechanically ground, cleaned, and dried; (3) The low-temperature bonding glass solder paste is evenly applied to the surfaces of YSZ ceramic and aluminum-silicon alloy to be welded, and then placed in opposite contact to obtain the welded joint; (4) After heating the connector to be welded to the welding temperature, heat preservation treatment is performed, and then cooling is performed to finally obtain the YSZ ceramic-aluminum-silicon alloy welded joint.

[0026] Specifically, in step (1), sanding is performed using 180, 800, and 1800 grit sandpaper in sequence, and the drying method in steps (1) and (3) is natural drying.

[0027] Optionally, the cleaning method in step (1) is to place the aluminum-silicon alloy in acetone solution and anhydrous ethanol in sequence for ultrasonic vibration cleaning, and the cleaning time is 10-15 min.

[0028] In step (2), the surface roughness of the YSZ ceramic to be welded is 0.07~0.09μm. Then, the YSZ ceramic is placed in acetone solution and anhydrous ethanol in sequence for ultrasonic vibration cleaning for 10-15 minutes.

[0029] Optionally, the coating thickness of the glass solder paste in step (3) is 180~200μm; In step (4), preheating is performed before welding. During preheating, the temperature is increased to 250°C at a rate of 5-8°C / min and held for 40-60 minutes. During welding, the temperature is increased to 420-500°C at a rate of 5-8°C / min and held for 20-40 minutes.

[0030] The beneficial effects of this application include, but are not limited to: 1. The low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys of this application adopts a quaternary system of bismuthate glass solder, which will not oxidize in the air environment. Compared with metal solder, it has better compatibility with ceramics, can fully wet the base material, and can form a connection through chemical bonding at low temperature (≤500℃) in the atmospheric environment. It does not require vacuum, inert atmosphere or metallization pretreatment, has low requirements for the welding environment, and effectively saves production costs.

[0031] 2. The low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys of this application has a high content of Bi2O3 and an appropriate amount of CuO. The synergistic effect of these two factors significantly reduces the viscosity of the glass melt and improves the wetting of the ceramic / aluminum substrate, resulting in a continuous and dense glass bonding layer. By adjusting the composition to control the thermal expansion characteristics of the glass phase, the difference in thermal expansion coefficient between the glass and aluminum-silicon alloys is reduced, which helps to reduce the risk of residual stress and interface cracks generated during cooling.

[0032] 3. The low-temperature bonding method of YSZ ceramics and aluminum-silicon alloys in this application, in conjunction with glass solder paste of specific components, controls the welding temperature at 420~500℃, which is far below the solidus of aluminum-silicon alloys (577℃), thus avoiding alloy melting and deformation; in conjunction with the segmented preheating process, the organic carrier is fully volatilized, effectively reducing the porosity of the joint, improving the room temperature shear strength, and the process is simple and easy to control.

[0033] 3. The low-temperature joining method of YSZ ceramic and aluminum-silicon alloy of this application is simple, low-cost, and environmentally friendly. Moreover, the YSZ ceramic-aluminum-silicon alloy welded joint has high room temperature shear strength and dense microstructure, which ensures the reliability of the YSZ ceramic-aluminum-silicon alloy connection. Attached Figure Description

[0034] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 This is a microstructure diagram of the YSZ ceramic-aluminum-silicon alloy welded joint in Example 3 of this application; Figure 2 This is a microstructure diagram of the YSZ ceramic-aluminum-silicon alloy welded joint in Comparative Example 1 of this application; Figure 3 This is a microstructure diagram of the YSZ ceramic-aluminum-silicon alloy welded joint in Comparative Example 2 of this application; Figure 4 This is a microstructure diagram of the YSZ ceramic-aluminum-silicon alloy welded joint in Comparative Example 3 of this application; Explanation of symbols in the diagram: 1. Al50Si aluminum-silicon alloy; 2 and 7 are pores; 3 and 8 are glassy precipitates; 4. Zirconia matrix; 5. Yttrium oxide reinforcing phase; 6. Cracks. Detailed Implementation

[0035] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0036] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention. The preferred embodiments and materials in this patent are for illustrative purposes only.

[0037] In this application, YSZ ceramics are commercially available products, and Al50Si alloy is selected as the base material for the aluminum-silicon alloy.

[0038] Example 1 A low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys is prepared by mixing bismuthate glass powder and an organic carrier, wherein the mass ratio of bismuthate glass powder to organic carrier is (6-8):1. The bismuthate glass powder, by mass percentage, comprises the following raw materials: 75% Bi₂O₃, 15% B₂O₃, 6-8% SiO₂, and 2-4% CuO. The organic carrier includes terpineol, ethyl cellulose, ethyl acetate, 1,2-propanediol, and soybean lecithin, in a mass ratio of 60:10:15:7.5:7.5.

[0039] The preparation method involves mixing Bi2O3, B2O3, SiO2 and CuO powders in a roller mill according to a certain ratio, then placing the mixed powder in a muffle furnace and heating it to 1150℃ for 60 minutes to obtain molten glass. After that, the glass is quenched in water to obtain glass particles. The glass particles are then ground and sieved through a 1200-mesh sieve to obtain 10~20μm bismuthate glass powder.

[0040] A low-temperature bonding method for YSZ ceramic and aluminum-silicon alloy includes the following steps: (1) Grind, clean and dry the aluminum-silicon alloy surfaces to be welded; (2) The surface of YSZ ceramic to be welded is mechanically ground, cleaned, and dried; (3) Apply low-temperature bonding glass solder paste evenly to the surfaces of YSZ ceramic and aluminum-silicon alloy to be welded, and then place them in opposite contact to obtain the welded joints; (4) Place the connector to be welded in a muffle furnace, heat it to the welding temperature and then keep it warm, and then cool it to finally obtain the YSZ ceramic-aluminum-silicon alloy welded joint.

[0041] In step (1), the cleaning method involves ultrasonically cleaning the aluminum-silicon alloy by sequentially placing it in acetone solution and anhydrous ethanol for 12 minutes. In step (2), diamond grinding is used to polish the surface of the YSZ ceramic to be welded to a roughness of 0.07~0.09μm; then, the YSZ ceramic is ultrasonically cleaned by sequentially placing it in acetone solution and anhydrous ethanol for 12 minutes. In step (3), the coating thickness of the glass solder paste is 200μm. In step (4), preheating is performed before welding. During preheating, the temperature is increased to 250°C at a rate of 8°C / min and held for 40 min. During welding, the temperature is increased to 460°C at a rate of 8°C / min and held for 30 min.

[0042] Example 2 The difference between this implementation method and Example 1 is that in step (1), 77% Bi2O3, 13% B2O3, 7% SiO2 and 3% CuO powders are weighed according to their mass percentages. Other steps are the same, and finally YSZ ceramic-aluminum-silicon alloy welded joints are obtained. The room temperature shear strength is shown in Table 1.

[0043] Example 3 The difference between this implementation method and Example 1 is that in step (1), 80% Bi2O3, 10% B2O3, 7% SiO2 and 3% CuO powders are weighed according to their mass percentages. The other steps are the same, and the YSZ ceramic-aluminum-silicon alloy welded joint is finally obtained. Its room temperature shear strength is shown in Table 1.

[0044] Table 1. Process parameters and room temperature shear strength of welded joints in Examples 1-3

[0045] As shown in Table 1, within the parameter range specified in this application, the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint varies with the content of each raw material in the bismuthate glass powder. When the total mass percentage of Bi2O3 and B2O3 is constant, the higher the value of Bi2O3 / B2O3, the higher the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint. When the mass ratio of Bi2O3 to B2O3 is 8:1, the room temperature shear strength reaches a maximum of 15.82 MPa.

[0046] The YSZ ceramic-aluminum-silicon alloy welded joint of Example 3 was observed using a scanning electron microscope (SEM), and its microstructure was obtained as shown in the figure below. Figure 1 As shown, by Figure 1 It can be seen that the YSZ ceramic-aluminum-silicon alloy welded joint has a dense structure, with no unwelded areas and no cracks.

[0047] Example 4 The difference between this implementation method and Example 3 is that in step (1), 80% Bi2O3, 10% B2O3, 6% SiO2 and 4% CuO powders are weighed according to their mass percentages. Other steps are the same, and finally YSZ ceramic-aluminum-silicon alloy welded joints are obtained. The room temperature shear strength is shown in Table 2.

[0048] Example 5 The difference between this implementation method and Example 3 is that in step (1), 80% Bi2O3, 10% B2O3, 8% SiO2 and 2% CuO powders are weighed according to their mass percentages. Other steps are the same, and finally YSZ ceramic-aluminum-silicon alloy welded joints are obtained. The room temperature shear strength is shown in Table 2.

[0049] Table 2. Process parameters and room temperature shear strength of welded joints in Examples 3-5

[0050] As shown in Table 2, within the parameter range specified in this application, the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint varies with the content of each raw material in the bismuthate glass powder. Among them, when the total mass percentage of SiO2 and CuO is constant, the YSZ ceramic-aluminum-silicon alloy welded joint has the highest room temperature shear strength when the mass ratio of SiO2 to CuO is 7:3.

[0051] Example 6 The difference between this implementation method and Example 3 is that in step (5), the welding temperature is 420℃, and the other steps are the same. Finally, a YSZ ceramic-aluminum-silicon alloy welded joint is obtained, and its room temperature shear strength is measured as shown in Table 3.

[0052] Example 7 The difference between this implementation method and Example 3 is that in step (5), the welding temperature is 500℃, and the other steps are the same. Finally, a YSZ ceramic-aluminum-silicon alloy welded joint is obtained, and its room temperature shear strength is measured as shown in Table 3.

[0053] Table 3. Process parameters and room temperature shear strength of welded joints in Examples 3, 6-7

[0054] As shown in Table 3, within the parameter range specified in this application, the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint first increases and then decreases with the increase of temperature during the welding process. When the temperature is 460℃, the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint is the highest, reaching 15.82MPa.

[0055] Example 8 The implementation method differs from that of Example 3 in that: in step (5), the welding process is kept at a temperature of 20 min, and the other steps are the same. Finally, a YSZ ceramic-aluminum-silicon alloy welded joint is obtained, and its room temperature shear strength is measured as shown in Table 4.

[0056] Example 9 The implementation method differs from that of Example 3 in that: in step (5), the welding process is kept at a temperature of 40 min, and the other steps are the same. Finally, a YSZ ceramic-aluminum-silicon alloy welded joint is obtained, and its room temperature shear strength is measured as shown in Table 4.

[0057] Table 4. Process parameters and room temperature shear strength of welded joints in Examples 3, 8-9

[0058] As shown in Table 4, within the parameter range specified in this application, the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint first increases and then decreases with the increase of the holding time during the welding process. When the holding time is 30 min, the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint is the highest, reaching 15.82 MPa.

[0059] In summary, the optimal conditions for brazing YSZ ceramics and aluminum-silicon alloys in this application are: a temperature of 250°C and a holding time of 40 min during the preheating process, and a temperature of 460°C and a holding time of 30 min during the welding process.

[0060] Example 10 The difference between this implementation method and Example 3 is that in step (4), the mass ratio of bismuthate glass powder to organic carrier is 6:1, and the other steps are the same. Finally, YSZ ceramic-aluminum-silicon alloy welded joint is obtained, and its room temperature shear strength is shown in Table 5.

[0061] Example 11 The difference between this implementation method and Example 3 is that in step (4), the mass ratio of bismuthate glass powder to organic carrier is 8:1, and the other steps are the same. Finally, YSZ ceramic-aluminum-silicon alloy welded joint is obtained, and its room temperature shear strength is shown in Table 5.

[0062] Table 5. Process parameters and room temperature shear strength of welded joints in Examples 3, 10, and 11.

[0063] As shown in Table 5, within the parameter limits specified in this application, the YSZ ceramic-aluminum-silicon alloy welded joint exhibits the highest room temperature shear strength of 15.82 MPa when the mass ratio of bismuthate glass powder to organic carrier is 7:1.

[0064] Comparative Example 1 The difference between this implementation method and Example 3 is that in step (1), 80% Bi2O3, 10% B2O3, and 10% SiO2 powders are weighed according to their mass percentages, i.e., no CuO is added. The other steps are the same, and finally, a YSZ ceramic-aluminum-silicon alloy welded joint is obtained. Its room temperature shear strength is shown in Table 6. The YSZ ceramic-aluminum-silicon alloy welded joint is observed by scanning electron microscopy (SEM), and its microstructure is shown in Table 6. Figure 2 As shown.

[0065] Table 6. Process parameters and room temperature shear strength of the welded joints of Example 3 and Comparative Example 1

[0066] As shown in Table 6, the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint in Comparative Example 1 is 0 MPa, indicating that a reliable connection has not been formed; Figure 2 It can be seen that cracking occurred on the side of the weld near the YSZ ceramic. This was because the absence of CuO changed the coefficient of thermal expansion of the glass solder, resulting in a mismatch in the coefficient of thermal expansion between it and the YSZ ceramic. This caused thermal stress concentration and cracking, which compromised the joint performance.

[0067] Comparative Example 2 The difference between this implementation method and Example 3 is that in step (4), the mass ratio of bismuthate glass powder to organic carrier is 9:1, while the other steps are the same. Finally, a YSZ ceramic-aluminum-silicon alloy welded joint is obtained, and its room temperature shear strength is shown in Table 7. The YSZ ceramic-aluminum-silicon alloy welded joint is then observed using a scanning electron microscope (SEM), and its microstructure is shown in Table 7. Figure 3 As shown.

[0068] Table 7. Process parameters and room temperature shear strength of the welded joints in Example 3 and Comparative Example 2

[0069] As shown in Table 7, the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint in Comparative Example 2 is 7.15 MPa, which is significantly lower than the shear strength of the joint prepared in Example 3; Figure 3 It is known that there are a large number of pores in the weld. The reason is that there is too little organic carrier and the weld fluidity is poor, which cannot fully wet the surface of the base material. This leads to the formation of a large number of pores during the welding process, which harms the weld quality and reduces the joint strength.

[0070] Comparative Example 3 The difference between this implementation method and Example 3 is that in step (5), the welding temperature is 550℃, while the other steps are the same. The YSZ ceramic-aluminum-silicon alloy welded joint is finally obtained, and its room temperature shear strength is shown in Table 8. Furthermore, the YSZ ceramic-aluminum-silicon alloy welded joint is observed microscopically using a scanning electron microscope (SEM), and its microstructure is shown in the figure below. Figure 4 As shown.

[0071] Table 8. Process parameters and room temperature shear strength of the welded joints of Example 3 and Comparative Example 3

[0072] As shown in Table 8, the room temperature shear strength of the YSZ ceramic-aluminum-silicon alloy welded joint in Comparative Example 3 is 9.44 MPa. The shear strength decreases significantly after the temperature exceeds the range specified in this application. Figure 4 It is known that there is a serious crystallization phenomenon at the joint. The reason is that the welding temperature increases the rate of atomic diffusion, promotes the formation of crystal nuclei, and thus increases the tendency to crystallize. The thermal expansion coefficients of the crystalline phase and the glass phase are quite different, which leads to a drastic change in the thermal expansion coefficient and a mismatch, which has an adverse effect on the joint performance.

[0073] In summary, the glass solder paste prepared using the raw materials specified in this application and the low-temperature joining process for welding YSZ ceramic and aluminum-silicon alloy exhibit high shear strength and excellent mechanical properties. Furthermore, this process does not require vacuum, inert atmosphere, or metallization pretreatment, has low requirements for the welding environment, saves production costs, and is conducive to industrial promotion.

[0074] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0075] The above description is merely an embodiment of this application and is not intended to limit the scope of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of the claims of this application.

Claims

1. A low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys, characterized in that, It is prepared by mixing bismuthate glass powder and organic carrier, with a mass ratio of bismuthate glass powder to organic carrier of (6-8):1; The bismuthate glass powder comprises the following raw materials by mass percentage: 75-80% Bi2O3, 10-15% B2O3, 6-8% SiO2, and 2-4% CuO.

2. The low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys according to claim 1, characterized in that, The mass ratio of Bi2O3 to B2O3 in the bismuthate glass powder is (5.5-8):

1.

3. The low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys according to claim 1, characterized in that, The mass ratio of SiO2 to CuO in the bismuthate glass powder is (6-7):(3-4).

4. The low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys according to claim 1, characterized in that, The organic carrier comprises terpineol, ethyl cellulose, ethyl acetate, 1,2-propanediol and soybean lecithin, in a mass ratio of (60-62):(10-12):(13-15):(7.5-8):(7.5-8).

5. The low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys according to claim 1, characterized in that, The particle size of the bismuthate glass powder is 10~20μm.

6. The low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys according to claim 1, characterized in that, The preparation method involves mixing Bi2O3, B2O3, SiO2 and CuO powders in a certain proportion, heating and holding the mixture, water quenching and grinding to obtain the bismuthate glass powder.

7. The low-temperature bonding glass solder paste for YSZ ceramics and aluminum-silicon alloys according to claim 6, characterized in that, The heating temperature is 1150-1170℃, and the temperature is maintained for 60 minutes. After grinding, the mixture is sieved through a 1200-mesh sieve.

8. A low-temperature bonding method for YSZ ceramic and aluminum-silicon alloy, characterized in that, Using the low-temperature bonding glass solder paste as described in any one of claims 1-7, the method includes the following steps: (1) Grind, clean and dry the aluminum-silicon alloy surfaces to be welded; (2) The surface of YSZ ceramic to be welded is mechanically ground, cleaned, and dried; (3) The low-temperature bonding glass solder paste is evenly applied to the surfaces of YSZ ceramic and aluminum-silicon alloy to be welded, and then placed in opposite contact to obtain the welded joint; (4) After heating the connector to be welded to the welding temperature, heat preservation treatment is performed, and then cooling is performed to finally obtain the YSZ ceramic-aluminum-silicon alloy welded joint.

9. The low-temperature joining method between YSZ ceramic and aluminum-silicon alloy according to claim 8, characterized in that, The cleaning method in step (1) is to place the aluminum-silicon alloy in acetone solution and anhydrous ethanol in sequence for ultrasonic vibration cleaning, and the cleaning time is 10-15 minutes. In step (2), the surface roughness of the YSZ ceramic to be welded is 0.07~0.09μm. Then, the YSZ ceramic is placed in acetone solution and anhydrous ethanol in sequence for ultrasonic vibration cleaning for 10-15 minutes.

10. The low-temperature joining method between YSZ ceramic and aluminum-silicon alloy according to claim 8, characterized in that, In step (3), the coating thickness of the glass solder paste is 180~200μm; In step (4), preheating is performed before welding. During preheating, the temperature is increased to 250°C at a rate of 5-8°C / min and held for 40-60 minutes. During welding, the temperature is increased to 420-500°C at a rate of 5-8°C / min and held for 20-40 minutes.

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