Exploration of the Influence Mechanism of La Doping on the Arc Erosion Resistance of Ag/SnO₂ Contact Materials by a Laser-Simulated Arc

To explore the influence mechanism of La doping on the arc erosion resistance of Ag/SnO₂ contact materials, SnO₂ and La-doped SnO₂ are prepared by a chemical coprecipitation method, and then Ag/SnO₂ and La-doped Ag/SnO₂ contact materials are prepared by a powder metallurgy process. The microstructures and phase structures of the Ag/SnO₂ and La-doped Ag/SnO₂ contact materials before and after arc erosion are analyzed. A laser-simulated arc is used as the experimental arc to explore the micromorphology and physicochemical properties of SnO₂ and La-doped SnO₂ after laser-simulated arc erosion. The results show that the density, hardness and conductivity of the La-doped Ag/SnO₂ contact material all increase first and then decrease with an increasing La content, reaching their highest values at a La/Sn molar ratio of approximately 0.25. La doping improves the dispersion of SnO₂ in the Ag matrix and reduces the mass loss of the La-doped Ag/SnO₂ contact material during the arc erosion process. Under the action of a laser-simulated arc, although both parts of the SnO₂ and La-doped SnO₂ transform into SnO, most of the SnO₂ sample forms large aggregates, while the La-doped SnO₂ sample forms small, spherical particles that are well dispersed. Finally, a mechanism is proposed whereby La doping enhances the arc erosion resistance of Ag/SnO₂ contact materials.