Key role of Ti₂SnC surface oxides in tailoring interfacial diffusion behavior and electrical contact properties of Ag-based composites

To clarify the role of Ti₂SnC surface oxides in the arc erosion resistance of Ag-based electrical contacts, a preoxidation strategy is employed to construct a controllable oxide layer at the Ag/Ti₂SnC interface. The results show that preoxidation induces surface decomposition of Ti₂SnC, leading to the in situ formation of a TiO₂-dominated oxide layer and promoting the diffusion of Sn into the Ag matrix. Although such interfacial reconstruction decreases the initial density, tensile strength, and electrical conductivity, it enhances local solid-solution strengthening and increases interfacial hardness. After 10,000 arc discharge cycles, the preoxidized Ag/Ti₂SnC@TiO₂ composite exhibits lower mass loss, shorter average arcing time, and lower arc energy. Combined with the post-erosion surface morphology, the results suggest that the preformed oxide interface regulates interfacial diffusion behavior, which further affects arc-root attachment and migration, thereby suppressing localized arc action and molten Ag splashing. This study reveals the role of Ti₂SnC surface oxides in regulating interfacial structure and arc erosion behavior, providing insights into the interfacial design of Ag/MAX-phase electrical contact materials.