Enhanced mechanical properties and oxidation resistance of (Ti,W,Mo,Ta)(C,N)-doped binderless Ti(C,N)-based ceramics

Abstract

Binderless Ti(C,N)-based ceramics were fabricated via spark plasma sintering using Ti(C,N) and (Ti,W,Mo,Ta)(C,N) powders as starting materials. Thermal analysis results indicated that, compared with Ti(C,N) powders, the solid solution powders possessed higher activation energy for oxidation, reducing oxidation susceptibility during preparation and promoting densification during sintering. As the content of (Ti,W,Mo,Ta)(C,N) increased, the relative density and transverse rapture strength were continuously enhanced. The sample containing 80 wt % solid solution exhibited the highest hardness and fracture toughness. Additionally, the utilization of (Ti,W,Mo,Ta)(C,N) significantly enhanced oxidation resistance, which was attributed to its promotion of the anatase-to-rutile phase transformation of the oxidation products, owing to the incorporation of W, Mo, and Ta into the Ti(C,N). During the initial stage of oxidation, the oxidation products of (Ti,W,Mo,Ta)(C,N) rapidly transformed to rutile-type oxides with high stability. This mechanism inhibited volume changes and crack formation, resulting in dense and flat oxidized surfaces.