Morphology-controllable synthesis and thermal decomposition of Ag and Ni oxalate for Ag-Ni alloy electrical contact materials

Abstract Two silver and nickel oxalate precursors with different morphologies (plates and particulates) were synthesized via precipitation of Ag + and Ni 2+ ions by C 2 O 4 2 − . In the case of high oxalate concentration and low pH value, the precursor was composed of Ag 2 C 2 O 4 hexagonal plates with NiC 2 O 4 ·2H 2 O plates adhered onto the surfaces. Low oxalate concentration and neutral pH resulted in the formation of irregular silver and nickel oxalate particles. Metallic Ag-Ni powders can be directly obtained at 400 °C in inert gas by thermal decomposition of the precursors. Finally, two Ag-matrix electrical contact materials reinforced by nickel with different morphologies (plates and particles) were prepared using the metallic Ag-Ni powders derived from the two typical precursors, respectively. Both samples show hardness and electrical conductivity that outperform the ASTM standard. The sample reinforced by Ni plates shows an even better performance of electrical conductivity. While the sample reinforced by dispersed nickel particles exhibits a better anti-arc and anti-erosion performance.