Contact resistance characteristics of Ag-SnO2 contact materials with high SnO2 content

The contact resistance and surface morphologies characteristics of Ag-SnO2 contact materials with high SnO2 content was investigated in make-and-break operations. The microstructure and arc eroded surface morphologies of Ag-SnO2 samples were researched by Scanning Electron Microscopy (SEM). The surface profiles and average surface roughness Sa of arc eroded Ag-SnO2 samples were also analyzed by Scanning Laser Microscope (SLM) 3D surface technique. With the SnO2 content increase from 15 wt.% to 30 wt.%, it was found that contact resistance of Ag-SnO2 materials increased by 33% and stabilize in 5 mΩ when contact force over than 70 N. The surface morphologies of arc eroded Ag-SnO2 samples were stable and uniform compared with the original samples. The theoretical analysis and experimental results of contact resistance characteristic indicated that contact force is the predominant factor for the contact resistances of Ag-SnO2 materials with high SnO2 content and contact resistance of high SnO2 content Ag-SnO2 materials can be reduced significantly by increasing the contact force.