Effect of ultra-fine TiC0.5N0.5 on the microstructure and properties of gradient cemented carbide

To increase the performance of cemented carbide, it was common to coat the wear surfaces with thin layers of hard materials. Cemented carbides with surface zone depleted of hard cubic phase and enriched in ductile binder phase were commonly used as the substrates. At the present, the so-called “gradient cemented carbides” were usually prepared by adding TiN or medium-sized TiCN, and a two-step sintering process including pre-sintering in nitrogen and gradient sintering in vacuum was usually adopted. In this paper, gradient cemented carbide based on WC–5.19 wt.%Ti–9.2 wt.%Co was prepared by simple vacuum sintering with the addition of 0.13 μm ultra-fine TiC0.5N0.5, compared with medium-sized TiN or TiCN. The result showed that gradient cemented carbide prepared with 0.13 μm ultra-fine TiC0.5N0.5 had better properties. With the increase of ultra-fine TiC0.5N0.5 content, the thickness of gradient surface zone decreased. TiCN coatings were deposited on gradient substrate and conventional substrate by moderate temperature chemical vapor deposition (MTCVD), respectively. Gradient substrate resulted in better adhesion and cutting performance.