Enhancement of Arc Erosion and Welding Resistance in Ag‐SnO₂ Contacts through WO₃ and Ag₂WO₄ Additives

To improve both welding and arc erosion resistance of AgSnO 2 contact material, the WO 3 and Ag 2 WO 4 are designed as additives with consideration of the arc extinction ability of WO 3 and the expected improvement of interface between Ag and SnO 2 through Ag 2 WO 4 . The Ag‐8 wt%SnO 2 contact materials without, and with WO 3 and Ag 2 WO 4 additions are prepared, and the electrical contact tests are performed for 10 000 switching operations at 24 V/20 A. The microstructure, eroded morphology, arc characteristics, material transfer, and welding behavior are investigated, and the arc erosion mechanism is discussed as well. The results show that both WO 3 and Ag 2 WO 4 have a good combination with Ag and SnO 2 , and the melting and coating effects of Ag 2 WO 4 happen during sintering owing to its low melting point. Compared with the material without addition, the mass loss rate decreases by over 50% with WO 3 addition, and it further decreases to near the zero with Ag 2 WO 4 addition. Moreover, the WO 3 and Ag 2 WO 4 additions also results in the decrease of welding force. The good performance can be attributed to the generated Ag 2 WO 4 , which is helpful for the dispersed distribution of SnO 2 at the eroded area.