Impact of convection-diffusion and flow-path interactions on the dynamic evolution of microstructure: Arc erosion behavior of Ag-SnO2 contact materials

Arc erosion behavior of Ag-30SnO(2) (wt.%) composite and its microstructural evolution is complex due to the interaction of gravity segregation with liquid evaporation. This paper was focused on understanding the dynamic microstructural evolution of Ag-30SnO(2) materials in the arc erosion systems. The micro-structures and arc erosion characteristics of Ag-30SnO(2) materials were investigated. Further, the movable and stationary contacts were selected as the models by phase identification and microstructure analysis.The arc erosion behaviors of Ag-SnO2 contact materials were studied using the computational fluid dynamics (CFD) method. Mathematical models and simulation results indicated that the dynamic microstructural evolution of movable and stationary contacts were strongly influenced by the convection-diffusion and the flow-path ((c(1)/l(1) ) + (C-g/l(g))). In stationary contact, the convection-diffusion can cause the much more fluctuation of del(del C-Ag ) and del(del C-SnO2) at the concavity of pyramid-likeconcentration curves. Thus, this flow-path with nearly linear, which led to the serious SnO2 enrichment in the surface of molten pool. In contrast, in movable contact, the relatively mild fluctuation of del(del C-Ag) and del(C-snO2) were induced by convection-diffusion in the pyramid-like concentration curves, as result, the serious Ag enrichment can be formed in the surface of molten pool due to the flow-path with gradually fluctuation. (C) 2018 Elsevier B.V. All rights reserved.