Anti-arc erosion capability and mechanism of Ag-Ni-La2Sn2O7 composites in different atmospheres
La2Sn2O7 powder was prepared by chemical coprecipitation method,and Ag-Ni-La2Sn2O7(85∶12∶3)composites were prepared by vacuum hot-pressing sintering method.Arc erosion experiments of the Ag-Ni-La2Sn2O7 composites were carried out in air,N2 and SF6 atmospheres,respectively.The surface morphology of the composites after arc erosion was analyzed by thermal field emission scanning electron microscopy(SEM)and three-dimensional laser confocal scanning microscopy(3D LSCM),and the composition of the samples after arc erosion was analyzed using energy dispersive spectrometer(EDS)and X-ray photoelectron spectroscopy(XPS).The behavior and mechanism of arc erosion of the Ag-Ni-La2Sn2O7 composites in different atmospheres were analyzed.The results show that the Ag-Ni-La2Sn2O7 composites have a large erosion area and small surface roughness in air and N2 atmosphere,while the erosion area significantly decreases in SF6 atmosphere,accompanied by an increase in surface roughness.After arc erosion in an air atmosphere,all metal elements are oxidized,generating Ag2O,NiO,La2O3 and SnO2.In an N2 atmosphere,due to insufficient O2-,La2O3,Ni and some SnO2 are generated after arc erosion,while the remaining Sn and Ag remain in a metallic state.In an SF6 atmosphere,the metal elements are fluorinated after arc erosion,generating AgF,NiF2,LaF3 and SnF4.