Arc erosion dynamic of island- and skeleton-restricted microstructure evolution modes in Ag–CuO contact materials

Abstract

Tuning the microstructure to optimize the arc erosion properties of contact materials via the dynamic model is quite important for their application in switches. In this work, we prepared Ag–CuOS (with skeleton CuO) and Ag–CuOI (with island CuO) materials to investigate the effects of microstructure on arc erosion resistance. In parallel, the three-dimensional models of Ag–CuO contacts are reconstructed by phase identification and microstructure analysis, then the arc erosion dynamic of microstructure evolution modes are tracked and studied using computational fluid dynamics (CFD) simulations. Simulation and experiment results both show that the repetitive thermal impact can cause the formation of crater surface and smooth surface in Ag–CuOI and Ag–CuOS, respectively. The local gap of Ag–CuOS contact can work as the driving force to reconstruct CuO skeleton, the newly formed CuO with anisotropic microstructure that can restrict the segregation and evaporation of Ag in molten pool. For the Ag–CuOI contact, the arc erosion merely restructures the initial island of CuO, and the continuous erosion is hardly restricted by this microstructure. Subsequently, we further quantify and evaluate the microstructural continuity of CuO. The results indicate that the CuO microstructure of Ag–CuOS shows a lower continuity coefficient (αnc) and a better continuity than that of Ag–CuOI during the arc erosion process.