Microstructure, mechanical and tribological properties of multilayer graphene reinforced WC-10Ni3Al prepared by microwave sintering

Abstract

The multilayer graphene (MLG) reinforced WC-10Ni3Al cemented carbide was prepared by microwave sintering. The effects of the sintering temperature and MLG content on the microstructure and mechanical properties of the WC-10Ni3Al cemented carbide were investigated. The promotion effect and strengthening mechanism of MLG on WC-10Ni3Al by microwave sintering were explored. The tribological properties of WC-10Ni3Al and Ti6Al4V(TC4) were studied, and the wear mechanism of WC-10Ni3Al was revealed. The experiment result show that the WC-10Ni3Al-0.5 wt.% MLG sample sintered at 1450 °C had its greatest mechanical properties with a relative density of 96.9%, hardness of 1430 HV, flexural strength of 1410 MPa and fracture toughness of 15.7 MPa mm1/2, which were 4.2%, 12.2%, 24.4%, and 29.6% greater than those of the sample without MLG added, respectively. The reinforcing and toughening mechanisms of adding MLG in WC-10Ni3Al samples consist of fine crystal strengthening, crack bridging and deflection, MLG pulling out and bridging. The results of friction experiment show that the friction coefficient and wear rate of the WC-10Ni3Al samples were lower than those of YG8 (WC-8 wt. % Co cemented carbide). The WC-10 Ni3Al-0.5 wt.% MLG sample obtained the lowest friction coefficient of 0.35 and the lowest wear rate of 1.69 × 10−5 mm3N−1m−1. A stable solid lubrication film was produced on the friction surface of the WC-10Ni3Al samples, which was conducive to reducing the breakage and wear of WC grains. MLG can enhance the stability of solid lubrication film and reduce its friction coefficient.