Question

Mention one reason for the use of aluminum in thermite welding.

Answer 1

Thermite welding is a chemical welding process in which an exothermic reaction in which heat is produced, is used to supply the essential heat energy.

1)This reaction involves the burning of thermite, which is a mixture of fine aluminium powder and iron oxide in a ratio of about $1:3$ by weight.

2) Aluminium has a greater affinity for oxygen than iron. The reduction with aluminium is highly exothermic and generated the sufficient heat to melt the metal.

Thermite reaction:

$$\begin{gathered} 2\mathrm{Al}\left(\mathrm{s}\right)+{\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)\to {\mathrm{Al}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)+2\mathrm{Fe}\left(\mathrm{s}\right)+\mathrm{heat} \\ \mathrm{Aluminium}\mathrm{Iron}\mathrm{oxide}\mathrm{Aluminium}\mathrm{Iron} \\ \mathrm{oxide} \end{gathered}$$

That's why we use aluminium in thermite welding.