Effects of interfacial wettability on arc erosion behavior of Zn2SnO4/Cu electrical contacts

Interface wettability is a vital role in directly impacting the electrical contact characteristics of oxides/Cu-based composites under arc erosion. Exploring its influence mechanism, especially at atomic/electronic scales, is significant but challenging for the rational design of oxides/Cu contacts. Here, we designed Zn2SnO4/Cu electrical contacts aiming to solve the poor wettability of SnO2/Cu composites. It was found that Zn2SnO4 could remarkably improve the arc resistance of Cu-based electrical contacts, which was benefited by the excellent interface wettability of Zn2SnO4/Cu. The characterization of eroded surface indicated that Zn2SnO4 particles distributed uniformly on the contact surface, leading to stable electrical contact characteristic. Nevertheless, SnO2 considerably deteriorated the arc resistance of SnO2/Cu composite by agglomerating on the surface. The effect mechanism of wettability on arc resistance was investigated through density function theory (DFT) study. It revealed that strong polar covalent bonds across the Zn2SnO4/Cu interface contributed to improving the interfacial adhesion strength/wettability and thus significantly enhanced the arc resistance. For binary SnO2/Cu interface, ionic bonds resulted in weak interface adhesion, giving rise to deterioration of electrical contact characteristic. This work discloses the bonding mechanism of oxide/Cu interfaces and paves an avenue for the rational design of ternary oxide/Cu-based electrical contact materials. (C) 2021 Published by Elsevier Ltd on behalf of Chinese Society for Metals.