Study On Microstructure And Properties Of TiB₂ Bulk Ceramic Material Prepared By SPS

TiB2 single-phase ceramic material attracts increasing interest owing to its unique properties. It has been widely used as horniness phase in metallurgy, mechanical industry, military industry, chemical industry and electronic industry due to its high melting point, high strength, high hardness and high modulus of elasticity, especially its good mechanical property above 1000℃. Compared with other ceramic material, TiB2 single-phase ceramic material has good electrical conduction, so it can be electromachined. Nowadays, this material is intensively investigated because of it's high properties. However, it is difficult to sinter TiB2 single-phase ceramic material due to its bad sinter property.In this paper small-crystalline TiB2 bulk single-phase ceramic was prepared by spark plasma sintering (SPS). Ti/TiH2 nano powders were obtained through DC transferred arc plasma. Mechanical Alloyed (MA) was also used to make small size TiH2 powders. B nano-powders and Ti or TiH2 powders with different sizes were used as starting materials for SPS sintering. The effects of the sintering parameters on microstructure and properties were emphasized and the best technological parameters were obtained. The best sinter temperature is in the zone of 1550℃-1620℃, which is much lower than traditional methods and SPS method with TiB2 powder as reported.It was noted that there were three stages in the SPS process of preparing small-crystalline TiB2 bulk single-phase ceramic, which are primary stage, intermediate stage and terminal stage.X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM) were utilized to investigate the phase composition and the morphology characteristics of the products. According to XRD and SEM results, all the samples prepared by SPS are pure TiB2 without second phase. And some properties of the pure TiB2 samples (density, Vickers hardness, and flexural strength) were measured respectively. Results indicated that relative density of sintered TiB2 sample reaches 99.8%, the Vickers hardness reaches 31.9GPa and flexural strength reaches 373.5MPa.In conclusion, the properties of TiB2 bulks prepared by reacting composed SPS method are better than the products prepared by common sintering methods in many aspects, such as relative density, pure degree, mechanics properties et al. And it can be sintered at a lower temperature with short time and hence form low scale crystals. The experiments note that SPS process can short consolidation process. It is very important for preparation and appliance of TiB2 bulk single-phase ceramic with excellent properties and makes contribution to the research of TiB2 bulk single-phase ceramic.