What is thermit welding process?

Thermit welding (TW) is a process that uses heat from an exothermic reaction to produce coalescence between metals. The name is derived from ‘thermite’ the generic name given to reactions between metal oxides and reducing agents.

What is alumino thermite welding?

The generic alumino-thermic reaction is based primarily around the principle of the reduction of heavy metal oxides by aluminium. In the case of the Thermit welding process, the heavy metal oxides are those of iron producing end products of aluminium oxide, Al2O3, and iron, both in liquid form.

What is alumino-thermic welding where is it used?

The aluminothermic reaction is used for the production of several ferroalloys, for example ferroniobium from niobium pentoxide and ferrovanadium from iron, vanadium(V) oxide, and aluminium.

What is thermit welding with pressure?

Pressure Thermit Welding: In this process the superheated molten metal and the slag produced by the exothermic reaction of thermit are poured into a mould surrounding the metal pieces to be welded.

What is used in the thermit welding process?

In thermit welding process, a thermite material which is a composition of a metal oxide, aluminium and fuel is used to achieve exothermic reaction. A reaction between the metal oxide (mostly iron (iii) oxide) and aluminium powder is takes place.

How is molten steel used in aluminothermic welding?

In the aluminothermic welding process, molten steel is poured into a mould surrounding the gap between the rail ends to be joined. The rail ends are connected by the liquid metal. The principle of aluminothermic welding is based on an exothermic chemical reaction of aluminium powder and iron oxide, producing sufficient heat to cause melting.

How is aluminum used in the alumino thermite process?

All components for the aluminothermic process are used as powders or granules. Once the reaction is initiated by an external heat source, the aluminum reduces the oxygen from the metal-oxide, which will result in a liquid superheated aluminum-oxide Al2O3.

How is alumino thermic welding used in Indian Railways?

1.3 On Indian Railways Alumino-Thermic welding with short pre-heating process by using high silica sand mould (carbon dioxide dried) is being followed at present for welding rails of different chemistry and sections. Short pre-heating is mostly being done by air-petrol fuel mixture.