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Chemistry · Glossary

What is Aluminothermic reduction?

Definition 6.9 University Chemistry — Year 2 · Chapter 6 — Ellingham Diagrams and Metallurgy

An aluminothermic reduction is the reduction of a metal oxide by aluminium powder, possible for every oxide whose line lies above that of alumina, and so exothermic that the mixture melts: FeX2OX3+2 Al→AlX2OX3+2 Fe\ce{Fe2O3 + 2Al -> Al2O3 + 2Fe} (thermite) welds rails; CrX2OX3+2 Al→AlX2OX3+2 Cr\ce{Cr2O3 + 2Al -> Al2O3 + 2Cr} makes chromium free of carbon.

Thermite welding of a rail: the reaction of iron oxide with aluminium in the crucible above the joint gives liquid iron, which runs down into the mould between the two rail ends. (Photograph: PetrS., CC BY-SA 3.0, Wikimedia Commons.)
Thermite welding of a rail: the reaction of iron oxide with aluminium in the crucible above the joint gives liquid iron, which runs down into the mould between the two rail ends. (Photograph: PetrS., CC BY-SA 3.0, Wikimedia Commons.)
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