Vacuum brazing technology for ceramic and metal parts

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Ceramics have excellent insulation, corrosion resistance, wear resistance and high temperature resistance, but they are brittle and have poor processing performance. Metal materials have excellent room temperature strength, toughness, electrical conductivity and thermal conductivity, and form an obvious complementary relationship with ceramic materials in terms of performance.

Performance Differences between Ceramics and Metals

The differences between ceramics and metals in physical and chemical properties are mainly manifested in: 1. Different chemical bond structures: ceramic materials are mainly composed of ionic bonds and covalent bonds, while metal materials are mainly composed of metallic bonds. The two are almost infiltrated, so the wettability of ceramic and metal materials needs to be considered. 2. Different linear expansion coefficients: When heat sealing or mechanical connection is used, there will be a large residual stress at the joint between ceramics and metals, which will weaken the mechanical properties of the joint and even cause the joint to be damaged and cracked. Therefore, the thermal stress relief problem at the joint needs to be considered. Ceramic and metal materials have great differences in performance. How can we give full play to their respective strengths and realize the close connection between the two into a whole? Countless researchers have continued to study and explore, and finally successfully achieved the connection between the two through multiple channels and methods.

Vacuum brazing technology

1.Choose the right brazing material: According to the characteristics of ceramics and metals, choose the right brazing material to ensure the strength and reliability of the connection. Currently, there are silver copper welding, pure copper welding, silver, gold tin welding, etc., which can generally meet the use temperature of different working conditions.

2.Interface reaction control: Control the interface reaction between ceramics and metals to reduce the formation of interface brittle phases and improve the toughness and reliability of the connection.

3.Connection process optimization: Optimize the connection process, including the coating of brazing material, the control of connection temperature and pressure, etc., to improve the connection quality and efficiency.

4.Choose the right brazing method. The common brazing methods are:

1) Vacuum brazing technology

Vacuum brazing technology is suitable for various ceramic and metal materials that need to be welded in an oxygen-free environment, such as alumina, silicon nitride, silicon carbide and other ceramic materials and stainless steel, titanium, nickel and other metal materials. Since there is no oxygen in a vacuum environment, there will be no oxidation and corrosion problems, and better welding quality can be obtained. The advantages of vacuum brazing technology are high connection strength, good sealing performance, and excellent high temperature resistance. At the same time, it can also avoid oxidation and corrosion problems and improve the durability of welded joints.

2) High temperature brazing technology

High temperature brazing technology is suitable for connecting various ceramic and metal materials, such as alumina, silicon nitride, silicon carbide and other ceramic materials and stainless steel, titanium, nickel and other metal materials. It is a welding technology that connects ceramic and metal at high temperature. Due to the different thermal expansion coefficients of ceramics and metals, welding needs to be performed at high temperature to reduce the impact of the difference in thermal expansion coefficients on welding quality. The advantages of high temperature brazing technology are high connection strength, good sealing performance, and excellent high temperature resistance. It is suitable for applications in harsh environments such as high temperature, high pressure, and corrosion.

Vacuum Brazing Furnace