Exothermic welding (also known as thermite welding) is a method that uses the superheated molten metal produced by the exothermic reaction between metal oxides and metal aluminium to heat the metal and achieve bonding. Exothermic welding was initiated at the end of the 19th century, when H. Goldschmidt discovered that the exothermic reaction of aluminium powder and metal oxide could be initiated by external heat source, and once the reaction was self-sustaining, the general formula of this reaction was: metal oxide + aluminium (powder) alumina + metal + heat energy. Exothermic welding can mainly weld pure copper, brass, bronze, copper, copper clad steel, pure iron, stainless steel, forged iron, galvanized steel, cast iron and so on. The welding process is simple to operate, does not need external power and heat sources, and has low welding cost, stable and reliable quality. Its conductivity is the same as that of base metal. It is very suitable for welding field cables and other metal components, and for connecting copper-core cables with steel structures or copper-core cables during installation of cathodic protection system.
Advantages of exothermic welding:
(1) The current cut-off of the welding joint is equal to that of the conductor.
(2) The welding joint is permanent and will not cause high resistance due to loosening or corrosion.
(3) Welding joints are as tough as copper, and are not affected by corrosive products.
(4) Welding joints can withstand repeated large surge (fault) currents without degradation;