Mechanical properties and wear resistance of functionally graded WC–Co

Functionally graded tungsten carbide–cobalt (FG WC–Co) composites were fabricated using a carburization process that preferentially segregated cobalt away from the free surface, establishing a compositional gradient into the bulk of the material. The resulting surface, which is harder due to increased WC content, has potentially broad application in tools for rock drilling and metal machining. The microstructure and mechanical properties of FG WC-10 wt.% Co and FG WC-16 wt.% Co samples were compared to conventional WC–Co for hardness, wear, fracture toughness, transverse rupture strength (TRS), impact, compression strength, and compressive fatigue. The increased surface hardness of the functionally graded materials resulted in substantially improved wear resistance, from 40% to 80%, compared to their conventional homogeneous WC–Co counterparts at equivalent levels of hardness, strength, and fracture toughness. FG WC–Co also exhibited improved impact and compressive fatigue resistance in a cutting element with a dome-topped geometric shape.

► Functionally graded WC–Co (FG WC–Co) was created by surface hardening/toughening of conventional WC–Co.
► Hardness, strength, wear resistance, toughness, impact and fatigue resistance of FG WC–Co were evaluated.
► FG WC–Co demonstrated substantially higher hardness hear surface and a 40 to 80% improvement in wear resistance.
► FG WC–Co showed improved impact and compressive fatigue resistance.