可加工性BN/Al_2O_3陶瓷基复合材料的制备  

Fabrication of machinable BN/Al_2O_3 ceramic composites

作　　者：李永利[1] 乔冠军[1] 金志浩[1] 

机构地区：[1]西安交通大学金属材料强度国家重点实验室,西安710049

出　　处：《中国有色金属学报》2002年第6期1179-1183,共5页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目 ( 5 0 0 72 0 17)

摘　　要：利用气相化学反应 ,以H3 BO3 和CO(NH2 ) 2 作为BN源 ,将纳米BN包覆到Al2 O3 颗粒表面 ,经热压烧结制备出高强韧可加工BN/Al2 O3 复合材料。材料的三点弯曲强度随BN含量的增加而缓慢降低 ,BN体积分数为30 %时 ,仍达到 44 6MPa;断裂韧性随BN含量的增加而得到显著改善 ,较单相氧化铝陶瓷提高近一倍。BN体积分数大于 2 0 %时 ,该复合材料可用WC钻头在普通台式钻床上钻孔 ,在小的轴向压力 (10N)下 ,钻孔速率大于 1mm/min ,钻孔边缘平整 ,没有崩裂现象 ,内壁光滑 ,粗糙度RZ=(6± 0 .5 ) μm。SEM观察显示 ,加工未带来明显的损伤。材料优异的力学性能及可加工性源自于基质中均匀分布的细小h BN的颗粒增韧机制及其易解理的层状结构特点。BN/Al 2O 3 ceramic composites with fine BN dispersions ranging from volume fraction 10% to 30% were successfully fabricated by hot-pressing the Al 2O 3 nanocomposite powders with nano-sized BN coating, which was developed through a chemical process using boric acid and urea as BN source. The fracture strength is decreased to a small degree compared to the Al 2O 3 monolithic ceramics, while the fracture toughness is considerably improved. The composites with BN volume fractions over 20 % are found to be easily drilled using WC drill bits without lubrication. SEM observations reveal that the holes are cleanly drilled with no evident cracking or chipping. The surface roughness (R Z) of drilled section is (6 ± 0.5) μm. High mechanical properties and the ease of machining are attributed to the fine microstructure owing to inhibition of matrix Al 2O 3 grain growth by the finer h-BN dispersions and the cleavage of fine h-BN dispersions with laminar structure and large aspect ratio.

关 键 词：复合材料 氧化铝 氮化硼 力学性能 可加工性 

分 类 号：TQ174.758[化学工程—陶瓷工业]