Improved arc erosion resistance of Ag/SnO₂ composites fabricated by Ag melt-infiltration in the SnO₂ skeleton

The typical Ag-SnO₂ contact materials in which SnO₂ dispersing in the Ag matrix suffer a poor arc erosion resistance because the individual SnO₂ particles segregate and form a SnO₂-rich layer under repeated arcing. Here, we introduce an architectured Ag/SnO₂ composites in which individual SnO₂ particles are bonding into a skeleton, fabricated by a novel method: (i) creating a porous SnO₂ matrix by sintering SnO₂ powders with NaCl space-holders, (ii) then infiltrated by Ag melt in the air. 95% relative density is achieved for the Ag/SnO₂ composites. The microstructure evolution during the sintering and infiltration are investigated. 10,000 times make-and-break operations are conducted to evaluate the arc erosion resistance of the architectured composite, the temperature rise of the prepared Ag-60vol.%SnO₂ composite decreases ∼90% compared with the particle dispersed composites. The microstructure of the arc-erased layer is analyzed and reveals that the SnO₂ skeleton effectively suppresses the formation of the SnO₂-rich layer, providing good arc erosion resistance and the potential for long lifetime contacts.