Enhancing oxidation resistance of Cu during repeated melting by the in-situ formation of protective oxide films

Copper is readily oxidizable in the air, especially at high temperatures. The existing anti-oxidation methods are mainly based on coatings that cannot survive in the harsh environment of repeated melting. This work introduces the in-situ formation of protective films along grain boundaries to improve the oxidation resistance under repeated melting. The Pb is more favorable oxidized than Cu and applied as the protective materials. Under repeated melting, the Pb dissolves in liquid Cu, then precipitates a reticular structure that wrapping up Cu grains and absorbing local oxygens. The formed PbO acts as a diffusion barrier to oxygen. The low-voltage contact test showed the Cu-Pb composite provides better oxidation resistance with a decreased contact resistance and temperature rise compared with pure Cu samples after 5,000 times arcing.