Properties and microstructure of nickel/graphite composites fabricated by electroless nickel plating and spark plasma sintering

Electroless plating was adopted to produce Ni-P-coated graphite powder which was subsequently used to prepare nickel/graphite composites via spark plasma sintering (SPS). Effects of sintering parameters on the microstructure and mechanical properties of the composites were investigated. Sintering temperature has a significant effect on the distribution of nickel, and coarsening of Ni3P precipitations occurs with the extension of holding time. Fully dense nickel/graphite composite with the interpenetrating network was achieved by SPS at 750 degrees C for 10 min as optimal conditions. The network consists of nickel and fine Ni3P particles. The flexure strength and hardness of the composite containing 68.2 vol.% graphite reached up to 157 MPa and 57.8 HV, respectively. The tribological properties of the composite obtained at optimal condition were characterized. Under applied load of 30-50 N and sliding speed of 1.55 m/s, the composite exhibited very low wear rate in the order of 10(-8) mm(3).N-1 m(-1) and stable friction coefficient from 0.12 to 0.18. The wear mechanism involved is delamination wear, oxidation wear and abrasive wear. [GRAPHICS] .