The THERMIT® reaction Fe2O3 + 2 Al => 2 Fe + Al2O3 is the reduction of iron oxide by powdered aluminium. The intense heat from the reaction results in the production of liquid metal, which is used to weld rails together without external energy.
These raw materials are thoroughly mixed with alloy additions to produce the THERMIT® portion, which is formulated to match the chemical, metallurgical and mechanical properties of the rail.
The THERMIT® portion is charged into a refractory crucible and the THERMIT® reaction initiated by the use of an igniter. On completion of the THERMIT® reaction, the liquid steel is automatically discharged from the bottom of the crucible into a refractory mould which encloses the rail ends. The mould incorporates geometric features that control the casting and solidification processes.
After cooling of the THERMIT® steel a further heat treatment can be carried out to improve its mechanical properties.
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