冻干法制备多孔氮化硼陶瓷及其成孔机理  

Preparation of Porous BN Ceramics by a Freeze-drying Technique and Their Pore-forming Mechanism

作　　者：石存兰[1] 薛文东[1] 刘晓光[1] 李勇[1] 孙加林[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083

出　　处：《硅酸盐学报》2015年第12期1701-1705,共5页Journal of The Chinese Ceramic Society

基　　金：北京市自然科学基金项目(2154052);中国博士后基金项目(2014M560044);中央高校基本科研基金项目(FRF-TP-14-004A1)资助

摘　　要：以h-BN为原料、MC为分散剂、PVA为结合剂、B2O3为烧结助剂,利用冷冻干燥法制备多孔BN陶瓷.对多孔陶瓷的物相和微观结构进行表征,分析了pH值对孔结构的影响.结果表明：冷冻干燥后的样品孔结构由树枝状孔和直通孔组成,平均孔径为30-150μm.pH值为10时,悬浮液Zeta电位最大,悬浮液分散性最好,冰晶生长过程中受到的阻力最小,样品平均孔径分布最均匀,体积密度和气孔率分别为0.4 g/cm^3和81.82％.1500℃烧结后,只有氮化硼的特征衍射峰.成孔机理为：冻干过程中水结冰后冰晶升华成孔,调节pH可改变浆料中颗粒的分散性以及冰晶生长过程中受到的阻力,从而影响孔结构的形成.Porous BN ceramics were prepared by a freeze-drying technique with h-BN as a raw material, MC as a dispersing agent,PVA as a binder, and B2O3 as a sintering aid. The effect of pH value of the ceramic slurry on the phase, pore structures and porosity ofporous BN ceramics was investigated. The results show that the aligned channels and dendritic pores with the pore size distributionrange of 30–150 μm are formed by the freeze-drying process. The sample fabricated from the slurry shows a homogeneousmicrostructure because that the absolute value of zeta potential is maximum when pH=10, correspondingly leading to the effectivedispersion of the ceramic particles in the slurry. The density and porosity of the sample at pH value of 10 are 0.4 g/cm^3 and 81.82 %,respectively. There is the pure BN phase in the sample sinterred at 1 500 ℃. The pore-forming mechanism can be ascribed to thesublimation of the ice crystals under vacuum during the freeze-drying process, where the dispersion of the particles in the suspensionand the resistance of the ice growth are both influenced by the pH of the suspension.

关 键 词：多孔氮化硼陶瓷 冷冻干燥法 微观结构 成孔机理 

分 类 号：TB321[一般工业技术—材料科学与工程]