Arc-Erosion Behavior and Mechanism of Ag/ZnO/La2Sn2O7 Composites in N2, CO2 and Their Mixtures with c-C4F8

Abstract:

La₂Sn₂O₇ powder was synthesized via chemical co-precipitation, and the Ag/ZnO/La₂Sn₂O₇ composites were prepared by hot-pressed sintering. The arc-erosion behavior and mechanisms of the composites were investigated at a constant voltage of 7 kV in CO₂, N₂, CO₂/c-C₄F₈, and N₂/c-C₄F₈ mixtures. The results show that the difference in arc breakdown current is very small across different atmospheres, while the erosion area, arc energy, and arc duration in mixed gas are clearly smaller than those in CO₂ and N₂. As the content of c-C₄F₈ rises, the breakdown strength in mixed gas increases gradually and is higher than that in CO₂ and N₂. The optical images of the arc show that the arc volume in mixed gas is obviously smaller than that in single-gas CO₂ or N₂, and the arc volume decreases gradually with the increase in c-C₄F₈ content. The erosion morphology analysis indicates that more pores, spattered particles, and cracks are present in the composites after arc-erosion in CO₂ and N₂. In the gas mixture, the erosion area is the smallest in the N₂/c-C₄F₈ (80/20) mixture, and particles and pores are significantly reduced. The low arc energy observed in N₂/c-C₄F₈ mixtures significantly reduces arc volume and erosion area. X-ray photoelectron spectroscopy results reveal partial decomposition of La₂Sn₂O₇ into La₂O₃ and SnO₂, while AgF and CF_x compounds are identified on eroded surfaces in c-C₄F₈ containing mixtures.