Self-propagating high temperature synthesis (SHS) is a new technology of synthetic materials, and SHS welding is a novel application field. SHS Welding is the technology of using the exothermic and product of SHS reaction. By using the combustion synthesis technology, the pressed powders are placed between the welded materials, the high-temperature reaction heat synthesized by the powder combustion and the synthetic products are used as filler materials to realize the connection between the welded materials under the pressure action.
The reaction process is similar to sintering, and the purpose of pressurization is to obtain a high density welded joint.
In general, SHS Welding has three processes: ignition, pressure, insulation.
1, many ways of ignition, such as arc, Spark, flame, strong current, high-temperature furnace, electron beam, laser, high-temperature radiation and microwave, chemical furnace. 2, pressure size and pressure time is the key to success or failure of welding. If the composite material of SHS is not pressurized, the pores of the material itself and the gas produced in the reaction will cause a lot of pores.
2，The reactants are not allowed to remain in the weld, and therefore must be compacted, usually by pressure during the reaction process.
3, pure pressure may not obtain high-density, should be at the same time insulation.
Compared with other welding methods, SHS welding has many advantages, mainly:
1, because the reaction is exothermic, the material can only be heated to a temperature below the melting point of hundreds of degrees Celsius, thus saving energy.
2, the solder can be added to enhance the phase, such as enhanced particles, short fiber, whisker, etc. to form composite materials.
3, welding is a synthetic gradient material, as solder to weld special materials, to overcome the parent material in the chemical, mechanical and physical properties of the mismatch.
4, SHS welding process of local heat release, can reduce the heat affected zone, to avoid the heat sensitive material microstructure damage, maintain the material performance.
5, because the green can be pressed into any shape, so SHS welding easily welded made products not easy to manufacture. 6. SHS welding is suitable for surface treatment of materials. SHS welding can be ceramic-ceramic, metal-ceramic, metal-metal welding.