Microstructure and mechanical properties of 3-D Ti-Si-N bulk materials synthesized by spark plasma sintering

Ti-Si-N coating has been widely reported with good thermal stability and excellent mechanical properties as protecting material for cutting tools. However, the coating thickness is usually in the range of 3-10 um by using PVD or CVD fabricating technique, which is not enough for the severe cutting environment. If the 2 dimensional ( 2-D ) Ti-Si-N film can be fabricated into 3-D bulk ceramic material, it should be a good candidate for high-speed or dry cutting conditions. In this paper, we try to investigate the relationship between microstructure and performance of Ti-Si-N bulk materials with different Si3N4 concentration synthesized by spark plasma sintering (SPS). The microstructure, relative density and Vickers hardness were determined to investigate the effect of varied Si3N4 contents. The results showed that Ti-Si-N bulk material exhibited typical nanocrystalline-amorphous structure similar with Ti-Si-N coating and outstanding mechanical performance. A maximum hardness of 2500HV0.05 could be obtained at 10 at.% Si3N4 content and the increasing Si3N4content will lower the relative density and hardness continually.