| Because of the attractive properties (such as high electrical conductivity,melting temperature,hardness,oxidation resistance and wear resistance),TiBj is used for a variety of applications. The major limitation in more widespread use of TiB2 is poor sinterability and brittleness in normal temperature. Nano-phase materials have been shown to exhibit significant improvements in fracture stress and ductility over their coarse-grain counterparts. So consolidated nano-TiBi may exhibit greater ductility,fracture toughness and ease of densification than conventional coarse-grained TiBi. Compared with coarse-grained TiB2,nanocrystalline TiBi may be more readily consolidated to high densities,thereby affording increased toughness without sacrifices in strength and hardness. TiBa nano-ceramic is a promising structure dmaterial.In this paper,titanium diboride (TiB2) powder synthesized by Self-Propagating High-Temperature Synthesis (SHS) was used as raw material. Mechanical alloying combining with purging of impurity technique was applied to fabricate nanocrystalline TiB2 powders. In addition,the particle size of powders milled for various time > mechanism of acid washing and thermodynamics performance of TiB2 nano-powder were studied. Furthermore,TiB2 nano-powder was sintered with Spark plasma sintering (SPS) method and the micro structure of samples,including the grain size were tested. At the same time,the mechanism of sintering process was analyzed.The results of analysis of powders with different milling time showed following milling processing,the particle size of TiB2 was decrease. But the trend of reducing was lower. The analysis of element indicated that WC impurity was inducted during the process of goal milling. Based on the TEM results of powder milled for 100h,the particle size of TiB2was about 150nm and there were also some large grains. The shape of powder was anomalous.The WC impurity was eliminated and pure TiB2 nanocrystalline powder wasachieved by acid washing process. The analysis of particle size showed that theparticle size of TiB2 nano-powder was about 50 nm. The grains of TiBi were uniform and the shape of grain was hexagon. The results of EPMA indicated there were some impurities in the powder after washing by acid. The contents of impurities were very little. Different thermal analysis proved that the thermodynamics performance of TiB2 nano-powder was very steady in vacuum. In air, the reactions were happened between 450-500.The reaction caused the increase of systematic quality.The TiB2 nano-crystalline powder was sintered by SPS technique under following conditions: sintering temperature: 1500, pressure: 30MPa, sintering atmosphere: vacuum, sintering temperature: 1 min. With different heating rate or sintering temperature, we achieved a series of sintering samples. The analysis of microstructure of samples showed that the grain of TiBa ceramics fabricated by nano-crystalline powders were very small. The distributing of grain size was uniform. The grain size of the sample sintered at 1500 was about 1-2 micron. Reducing heating rate enhanced the density of sample. But the grain size of sample with low heating rate was larger than that of high heating rate. With the heating rate of 200/min, the sintering sample had finest microstructure.The TiB2 micro-powder was sintered by SPS. The influence of sintering temperature or heating rate on the relative density and grain size was studied. The mechanism of SPS sintering process was analysis. We observed that they're some melt on the surface of TiB2 powder at the temperature far low than the melt point of TiB2, which indicated that there spark point between the particles during the SPS sintering process. The spark brought partial high temperature that caused the melting of TiB2.
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