Study on the In-situ Fabricated Titanium Nitride-based Ceramic Cutting Tool Materials Reinforced by Titanium Diboride

摘要

The titanium diboride reinforced titanium nitride-based ceramic cutting tool composite materials were fabricated by a new technology namely in situ synthesis followed by hot-pressed sintering. The experimental results showed that the highest density and the best mechanical properties of the composite material were obtained when the content of Ni was 5wt%. X-ray diffraction (XRD) was used to identify the phases of the composite. Microstructures of the composite were observed by means of scanning electron microscope (SEM). It is concluded that the sintered material was pure, no harmful reaction products was found;;with the increase of Ni content, the proportion of short rod-like TiB_2 increased, fracture toughness of the composite materials were improved because lots of TiB_2 were pulled out;;bridging phenomenon of short rod-like particles and metal particles were observed in the crack propagating process. The main toughening mechanisms of the composites were deflection and bridging of the crack as well as grains' pulling out.