Activated Sintering of TiC–TiB2 SHS–Powders

This work is part of a research project directed to the manufacture of high performance cutting tools by consolidation of ceramic powders produced by SHS (Self-propagating High Temperature Synthesis). The process used here was based on low/medium cost raw materials. The reaction of TiO2 and B4C with carbon and magnesium took place in argon atmosphere, yielding a TiC-TiB2 powder. In view of further liquid phase sintering as a TiC-TiB2 metal-bonded cermet, an extensive investigation on the sintering additives was performed. The most suitable metallic binders turned out to be Ni and Fe. The best results were achieved through addition of Mo2C as wettability activator to the metallic Ni phase. In particular, the vacuum sintering of the system 60%TiC-40%TiB2 with a binder addition of 15%Ni-7.5%Mo2C led to the achievement of cermets characterised by a sintered density of 95% of theoretical density and homogeneous microstructure. The hardness measurement on the sintered samples showed the achievement of good results (1650 HV), qualifying the new developed cermet compositions as suitable for cutting tools and wear-resistant applications.