Effect of CNTs content on the mechanical and arc-erosion performance of Ag-CNTs composites

Abstract

Adding strengthening phase is an important way to improve the arc erosion and anti-welding performance of Ag-based electrical contact materials. Ag-CNTs composites with different contents of CNTs were prepared by electroless silver plating, high-energy milling and powder metallurgy. The effect of CNTs addition on strengthening mechanism and arc erosion behavior of Ag-CNTs were investigated. The results show that agglomerating degree of the CNTs increases with the increase of content. CNTs distribute mainly at the grain boundaries and partially in the grains along the processing direction. The processing can disintegrate CNTs clusters which is beneficial for the dispersion of CNTs. With the increase of CNTs content, strength of the composite first increases then decreases while the elongation and electrical resistivity decreases.. The maximum yield strength (245 MPa) and tensile strength (296 MPa) was achieved when the CNTs content was 8 vol%. The electrical breakdown tests show that the addition of CNTs can obviously stabilize the arc and reducing welding. Materials transfer from the anode to the cathode and the transfer mass first decreases then increases with the CNTs content increasing. The Ag-CNTs composite with 8 vol% CNTs added presents the desired properties of stable arc and no obvious craters or pips on the eroded surface. Excessively high CNTs content will lead to the decreasing of strength and serious arc erosion.