Effect of CuO additives on the formation of SnO2-rich layers in Ag-SnO2 materials

Abstract

In order to investigate the effect of CuO additives on the formation of SnO2-rich layer in Ag-SnO2 contact materials, the laser rapid melting experiment was carried out on Ag-SnO2 contact materials for the purpose of simulating the rapid melting process of an instantaneously arc melted surface layer during arc erosion. The microstructure of laser melted and arc eroded Ag-SnO2 materials were investigated using scanning electron microscopy (SEM). The experimental results were also theoretical analyzed with two models dealing with the particle-dendrite interaction during solidification process. It was found that the Ag-SnO2 materials with CuO additives have found no SnO2-rich layer in the re-melted area and the SnO2 particles still stayed in Ag matrix because of the increasement of dragging force between Ag matrix and SnO2 particle. As the dragging force increase, the advance speed of SnO2 particles in front of S/L interface was lowered and SnO2 particles were apt to be engulfed by Ag matrix during solidification, so the CuO doped SnO2 particles were more difficulty to be pushed out of the Ag matrix than pure SnO2 particles. These results indicated that the effect of CuO additives on the formation of SnO2-rich layer in Ag-SnO2 contact materials was enhanced the wettability of SnO2 particles in Ag melt pool and restrained the SnO2 particles rise to the contacts surface.