Research On The Properties Of Nano-TiN Modified TiC-based Cermets And Their Cutters

TiC-based cermets have been widely used as a tool material in mechanical processing owing to its outstanding physical, mechanical and wear-resistant properties. In this thesis, the author developed the experimental research and theoretical analysis. Cermets cutters were designed and prepared, so it can be used in high speed cutting of metals and the wear mechanism of cermets cutter can be further consummated.First, research on the effect of Mo,Co addition on the properties and microstructure of cermets was done. Results reveal that different Mo addition makes the width, integrity and homogeneity of "SS" phase and the composition, quantity and distribution of binder change; consequently, the mechanical properties were affected. However, addition of Co has little effect.Second, 48TiC-10TiN(nm)-15WC-16Mo-5Co-5Ni-lC cermets cutters were prepared. By cutting normalized 45 steel and gray cast-iron with different kinds of tools (i.e., YG8, YT15 and 20Ni cermets), it has been found that under most cutting conditions 5Co+5Ni cutter is the best one. The main failure mode of this cutter is wear. Tipping happens only under big cutting quantities.Last, EDS analysis of surface composition of cutters and cuttings was done. The wear patterns of cutters were also observed. It has been found that when this cutter is used to cut normalized 45 steel and gray cast-iron, high temperature oxidization and diffusion phenomena appear active. So the properties of the cutter are decreased and the result is that wear quantity increases and cutter fails more quickly.