Write about the processes of thermite welding.
Answers
Thermite welding is similar like a casting process in which the molten state of metal is created by the chemical reaction. Its working can be summarized as follow. First both the work pieces which are needed to be weld, are cleaned. Now a wax pattern is created around the weld cavity.
Answer:
Reduction of ferric oxide by Aluminium is used in thermite welding. A mixture of ferric oxide and aluminium powder is called thermite. It is placed in crucible made up of silica. It is ignited with the help of magnesium ribbon attached to magnesium powder and barium peroxide which constitutes starting plug. Upon ignition, magnesium burns in the presence of Barium peroxide which helps ignition. As a result of heat produced, aluminium present in thermite reduce ferric oxide to iron.
Here, ∆ means heat.
2Al + Fe2O3 --∆--> Al2O3 + 2Fe + heat.
The heat evolved keeps iron in molten state. It escapes from the tapping hole and fills the gap of the broken articles.