WC+Co+graphene platelet composites with improved mechanical, tribological and thermal properties

WC+Co+graphene platelet (GPL) composites were processed by sintering at 1380 °C in argon and the influence of GPLs addition on the microstructure development as well as mechanical, tribological and thermal properties was investigated. A homogeneous distribution of GPLs could be achieved in the systems which resulted in a decreased WC grain size and an increased density for the systems with 0.35 vol% and 0.70 vol% GPLs content. With respect to the mechanical properties, the optimal GPLs content was 0.70 vol%, which led to the highest hardness of 1784.73 kgf/mm 2 , the highest bending strength of 2198.6 MPa and a high indentation crack resistance of 11.06 MPa·m 1/2 . The GPLs clusters in combination with porous regions acted as defects/fracture points. Further, the main toughening mechanisms included crack deflection, crack bridging and crack branching. The composites demonstrated improved tribological properties in comparison to the WC+Co system. The friction coefficient and wear rate decrease from 0.407 to 0.343 and 2.67 × 10 −6 mm 3 (m·N) −1 to 1.38 × 10 −6 mm 3 (m·N) −1 , respectively. It is attributed to the formation of tribofilm and enhanced mechanical properties of composites. The thermal conductivity of the composites was significantly enhanced from 85.2 W/(m·K) to 110.8 W/(m·K) on increasing the GPLs content.