Ancient and high development potential of welding technology, silver brazing introduction

【Summary Description】 Brazing (including micro-joining), diffusion welding and the derived transition liquid phase diffusion welding (TLP diffusion welding) and liquid phase interface diffusion welding (LID welding) should be the main joining methods studied by our special committee I. As for the scope of special connection, there is no clear definition, such as high-temperature self-propagating synthetic connection, which belongs to the special committee I or high-energy beam and special welding special committee (Ⅵ special committee); the explosion is divided into category I, Category V or pressure welding V is reasonable. Here, I mainly want to talk about the characteristics of brazing diffusion welding, which may sometimes involve high-temperature self-propagating synthetic connection, explosive welding, etc. First of all, the heating temperature of brazing and diffusion welding is generally much lower than the melting point of the substrate, so it has little effect on the physical and chemical properties of the substrate. The entire weldment is heated evenly, the stress and deformation are small, and it is easy to ensure the dimensional accuracy of the weldment. Secondly, brazing and related special joining techniques are highly productive. Brazing can complete the connection of multiple joints and parts at once. For example, the brazing seam length of the combustion chamber of the 750N liquid rocket engine manufactured by the former Soviet Union is 750m, which can be brazed at one time. For example, the stainless steel panel/corrugated plate core thrust chamber shell of the rocket engine is connected by brazing, and hundreds of welds are brazed at a time. Diffusion welding and explosive welding can achieve large-area structural connections, such as the manufacture of large composite laminates. Third, brazing technology can be used for weldments with complex structure, high precision requirements, poor joint openness, and poor accessibility. For example, vacuum brazing technology can realize the precise brazing of multi-layer aluminum alloy radar antennas and microwave devices with complex structures. However, the working blades and guide blades of the aero-engine high-pressure turbine with complex internal cooling channels can only be connected with high quality by brazing. Fourth, brazing and related special joining techniques are particularly suitable for the combined joining of various materials. It can not only connect regular metal materials, but also other metal materials that are difficult to connect by other welding methods, as well as non-metallic materials such as ceramics, glass, graphite, and diamond. In addition, the connection of dissimilar metals, metals and non-metallic materials is also easy. Therefore, many structures or materials that are difficult or even impossible to connect by other welding methods can be solved by brazing. The self-propagating high-temperature synthesis connection is particularly suitable for the connection of new structural materials, such as the connection of ceramics and metals, and the connection of intermetallic compounds such as NiAl and TiAl. Explosive welding can be used to join almost any metal, such as metals with different melting points (such as lead and tantalum), metals with different thermal expansion coefficients (such as titanium and stainless steel), and metals with different hardness and physical and chemical properties (such as copper and titanium, copper and aluminum, Copper and molybdenum, aluminum and stainless steel, etc.).). It can also be used to join non-metals and metals (such as ceramics and steel).

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The development history of brazing and special connection technology, and the application in various fields.

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According to different brazing process and temperature requirements, understand the corresponding type of silver solder paste.