Preparation and Sintering of Ultrafine B_4C Powders

A series of jet-milling experiments on B4C coarse powders with specific surface area of 0.52m2/g and median particle size of 20.4μm were carried out. Effects of jet-milling times, forming stress and sintering temperature on sintered densities of B4C were also studied. The results show that powders with particle size of less than 1μm can be obtained when jet-milled for more than 3 times. The powders jet-milled for 4 times, with specific surface area of 2.53m2/g and median particle size of 0.56μm, can be pressureless sintered to 78.6% TD at 2200℃ and 82.5% ＴD at 2250℃ for 1h, with average grain size of 28μm and 50μm, comprasive strength of 390MPa and 555MPa respectively.