Cadmium is used in Silver-Cadmium-Oxide (AgCdO) electrical power switching contacts because it provides the best known performance for switching off electrical current quickly and cleanly, and avoiding contact welding and premature failure. CdO particles are finely distributed in Ag matrix. Under the action of arc, CdO decomposes and vaporizes, which cools down the contact surface, so as to lower the arc energy and extinguish the arc.

AgCdO (current contact material in aerospace industry) is one of the most widely used contact materials in the world because of its outstanding performance. Nevertheless, due to environmental considerations, it will soon be completely forbidden by European environmental directives.

Recent investigations have led to the development and implementation of new environmentally friendly electrical contact materials in which the toxic CdO is replaced by less harmful metal oxides, while maintaining the good final properties. It was found that the Ag-SnO2 composite material meets most of the required properties.