Self-propagating high-temperature synthesis is a synthetic material, and the welding of ceramic composite pipes is a new application of the process. Ceramic composite pipe welding is the technology of SHS reaction of heat dissipation and its products to welding. Applying combustion synthesis technology, the molded and formed powder is placed between the materials to be welded, and the connection between the materials to be welded is realized under pressure by using the high-temperature reaction heat of combustion synthesis of the powder body and the synthesis products as filler materials. This reaction process is similar to sintering, and the purpose of pressurization is to obtain welded joints with high densities.
Generally speaking, there are three processes in ceramic composite pipe welding: ignition, increasing pressure, and insulation.
1. There are many ways of ignition, such as electric arc, electric spark, flame, strong current, high temperature furnace, electron beam, laser, high temperature radiation and microwave, chemical furnace, etc.
2. Increase the size of the pressure and pressurization time is the key to success or failure of welding. Ceramic composite pipe synthesis material if not pressurized, due to the pores of the material itself and the gas produced in the reaction, will lead to a large number of pores. It is not allowed to leave the reaction material in the weld, so densification, the usual method is to pressurize during the reaction.
3. Simply increasing the pressure may not be obtained, should be accompanied by insulation.
Compared with other welding methods, ceramic composite pipe welding has many advantages, mainly:
1. Due to the reaction heat dissipation, the material only needs to be heated to a few hundred centigrades below the melting point, which can save energy.
2. Welding material can be added to the reinforcing phase, such as reinforcing particles, short fibers, whiskers, etc., to form a composite material.
3. Welding is available to synthesize gradient materials, as solder to weld dissimilar materials to overcome the mismatch between the parent material in chemical, mechanical and physical properties.
4. Ceramic composite pipe welding process of local heat dissipation, can reduce the heat-affected zone, to avoid damage to the microstructure of heat-sensitive materials, to maintain the performance of the material.
5. Because the raw billet can be pressed into any shape, thus ceramic composite pipe welding easy to weld into products that are not easy to manufacture.
