The effects of oxide additives on the mechanical characteristics of Ag–SnO2 electrical contact materials

Abstract

The effects of oxide additives such as WO3, Cu2O, In2O3, etc. on the mechanical characteristics of Ag-8wt.%SnO2 contact materials were investigated. The tensile tests of the Ag–SnO2 materials prepared by powder metallurgy method were carried out on a MZ.Ms tensile machine. The fracture morphologies of the tensile samples were studied by a Scanning Electron Microscope (SEM). The fracture mechanism was simulated and analyzed utilizing ANSYS software. The results revealed that the addition of oxide additives increased the ultimate strengths and elasticity moduli of the Ag-8wt.%SnO2 contact materials. The maximum strength was achieved on the sample with addition of Cu2O, which reached up to 134.6 MPa. The stress concentration around SnO2 particles was relaxed with adding oxide additives. The initiation and propagation of the intergranular cracks in Ag–SnO2 contact materials were inhibited. Accordingly, the plasticity and creep resistance of the prepared materials were markedly improved. It was interesting that no visible intergranular cracks were generated in the Ag-8wt.%SnO2 contact materials when the SnO2 particles were decreased to about 70 nm. The mechanical properties of the Ag-8wt.%SnO2 nanocomposites were dramatically improved by adding In2O3. The mechanism was quite different from the Ag–SnO2 materials containing micron-sized SnO2 particles.