Reaction Process and Influence of WC Content on Microstructure and Mechanical Properties of Ti(C, N)-Based Cermets

Abstract

The incorporation of WC promotes the sintering and grain refinement of Ti(C, N)-based cermets, leading to superior mechanical and functional properties. Herein, we present the reaction process of Co–Ti–C–BN–WC system and influence of WC content on microstructure and mechanical properties of Ti(C, N)-based cermets. The results reveal that Ti(C, N) is produced due to the combination of C/TiN or TiN/TiC, whereas TiB₂ is formed due to the reaction between B/TiB or Ti/B. Moreover, (W, Ti)(C, N) solid-solution is synthesized due to the reaction of W and C with TiN in the liquid state. In addition, XRD analysis indicates the presence of a small amount of CoW₂B₂ and Co₃C phases with WC content of 15 and 20 mass%. Furthermore, the content of core-ring structure gradually increases with the increase of WC content from 5 to 20 mass%. Also, the grain size increases from 0.364 µm to 0.484 µm with increasing WC content from 5 to 20 mass%. On the other hand, the porosity initially decreases with increasing WC content, followed by a gradual increase. Consequently, the microhardness, fracture toughness and bending strength initially increase with increasing WC content, followed by a decrease. The maximum microhardness, fracture toughness and bending strength are found to be 2010 HV₁₀, 7.21 MPa·m^1/2, and 725 MPa, respectively.

Fig. 6 The SEM-BSE morphology of Ti(C, N)–TiB₂–WC–Co cermets with different amounts of WC after sintering at 1400°C: (a) 0 mass%; (b) 5 mass%; (c) 10 mass%; (d) 15 mass%; and (e) 20 mass%.