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.