Abstract :
Latest developments in relay applications are combining needs for low weld break forces, low arc erosion and material migration and excellent mechanical formability. This is due to trends like miniaturization, precious metal saving, and electrical loads with high inrush currents. Silver metal oxide contact materials were benchmarked, as they are widely used for those applications. Tensile tests were performed to compare mechanical workability. Advantages of pre-oxidized Ag-SnO2 materials were observed, especially at high total metal oxide contents. Model switch tests showed significantly reduced weld break forces on pre-oxidized Ag-SnO2 materials compared to powder metallurgical materials. Contact resistance and erosion/material transfer have been compared under ohmic-inductive load and showed a major influence of total metal oxide content. As shown by these tests, advanced contact materials based on Ag-SnO2 can combine the requested contact material properties for the diverse applications.
