六方BN陶瓷的高压气-固自蔓延高温合成

h BN produced by high pressure gas solid self propagating high temperature synthesis

采用高压气固自蔓延高温合成技术制备了产物密度为１ ．７０ ｇ／ｃｍ３ 的六方ＢＮ（ｈＢＮ） 陶瓷，其最高抗弯强度和硬度分别为４２ ．８ ＭＰａ 和１０８（ＨＶ） ； 分析了氮气压力和初始孔隙率对反应物点燃和产物的影响， 发现在适当的初始孔隙率和氮气压力条件下， 可以合成没有裂纹的ｈＢＮ 陶瓷产物， 其范围为：４８ ％ ≤ρ≤５２ ％ ，９５ ＭＰａ ≤ｐ ≤１１０ ＭＰａ。同时发现产物中的片状ｈＢＮ 颗粒为各向同性，ｈＢＮ 产物纯度较高， 在高的氮气压力条件下合成的ｈＢＮ 颗粒较大。片状ｈＢＮ

h BN ceramics were prepared from powders of B and h BN by means of high pressure gas solid self propagating high temperature synthesis technology. The density of h BN ceramics is 1.70 g/cm 3, the bending strength and the hardness of h BN ceramics were 42.8 MPa and 108(HV) respectively. The nitrogen pressure and porosity of reactants that influence ignition and products have a best scope, 95 MPa≤ p ≤110 MPa, 48%≤ ρ ≤52%, in which the steady combustion products can be obtained. By X ray diffraction, scanning electron microscopy and transmission electron microscopy, the phase and microstructure were analyzed. The higher the nitrogen pressure, the larger the h BN particle. The distribution of h BN particles is anisotropic. There are branches and twists in the h BN particles.