B4C超细粉末的制备及烧结

采用气流粉碎对Ｂ_４Ｃ粗粉（比表面积０．５２ｍ^２／ｇ，中位粒径２０．４μｍ）进行了一系列粉碎实验，研究了气流粉碎次数、成形压力和烧结温度对烧结密度的影响．结果表明，当粉碎次数达到３次后，可获得＜１μｍ的Ｂ_４Ｃ超细粉末．经过４次气流粉碎的Ｂ_４Ｃ超细粉末的比表面积为２．５３ｍ^２／ｇ，中位粒径为０．５６μｍ；粉末分别于２２００和２２５０℃压烧结１ｈ，其烧结密度分别达到理论密度的７８．６％和８２．５％，平均晶粒尺寸分别为２８和５０μｍ抗压强度分别为３９０和５５５ＭＰａ．

Preparation and Sintering of Ultrafine B4C Powders

A series of jet-milling experiments on B₄C coarse powders with specific surface area of 0.52m^2/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.