Study on the Properties of Ag-Nb₂AlC Composite as an Electric Contact Material

Ag-Nb₂AlC composite materials with a Nb₂AlC volume percentage ranging from 10% to 40% were prepared using the spark plasma sintering method. The composite with 10% Nb₂AlC achieved a high density of 99.2%. The microhardness exhibited a peak value of 84.8 HV at a Nb₂AlC content of 30%. The conductivity of the composite material decreases linearly with an increase in Nb₂AlC content, ranging from 0.134 MS·cm^-1 to 0.086 MS·cm^-1. A three-dimensional laser scanning microscope was employed to characterize the morphology following arc erosion, and the erosion area was subsequently measured. Results indicated that arc erosion was concentrated on the Ag-20 vol.% Nb₂AlC composite material, resulting in a smaller circular erosion area. As Nb₂AlC content increased to 30% and 40%, the arc shifted, leading to an expansion of the erosion area. Notably, the Ag-30 vol.% Nb₂AlC composite material exhibited the highest arc energy (3.401 kJ). The eroded surface displayed spattered particles and a convex morphology. Additionally, EDS and Raman spectroscopic analyses revealed the formation of Nb₂O₅, Ag₂O, and Al₂O₃ on the surface. The arc erosion mechanism was analyzed from an electrical perspective, indicating that the formation of the arc is attributed to the development of a positive streamer and air breakdown within a strongly nonuniform field. Consequently, the surface atoms of Ag-Nb₂AlC absorb energy, leading to the formation of metal ions that combine with the ionized air to create oxides. This research lays a theoretical foundation for the application of silver-based electrical contact materials.