Transactions of Nonferrous Metals Society of China The Chinese Journal of Nonferrous Metals

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中国有色金属学报

ZHONGGUO YOUSEJINSHU XUEBAO

第12卷    第6期    总第51期    2002年12月

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文章编号:1004-0609(2002)06-1179-05
可加工性BN/Al2O3陶瓷基复合材料的制备
李永利, 乔冠军, 金志浩

(西安交通大学 金属材料强度国家重点实验室,
西安 710049
)

摘 要: 利用气相化学反应, 以H3BO3和CO(NH2)2作为BN源, 将纳米BN包覆到Al2O3颗粒表面,经热压烧结制备出高强韧可加工BN/Al2O3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446MPa; 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20%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。

 

关键字: 复合材料; 氧化铝; 氮化硼;力学性能; 可加工性

Fabrication of machinable BN/Al2O3 ceramic composites
LI Yong-li, QIAO Guan-jun, JIN Zhi-hao

State Key Laboratory for Mechanical Behavior of Materials, Xi′an Jiaotong University,Xi′an 710049, China

Abstract:BN/Al2O3 ceramic composites with fine BN dispersions ranging from volume fraction 10% to 30% were successfully fabricated by hot-pressing the Al2O3 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 Al2O3 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 (RZ) 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 Al2O3 grain growth by the finer h-BN dispersions and the cleavage of fine h-BN dispersions with laminar structure and large aspect ratio.

 

Key words: composites; alumina; boron nitride; mechanical properties; machinability

ISSN 1004-0609
CN 43-1238/TG
CODEN: ZYJXFK

ISSN 1003-6326
CN 43-1239/TG
CODEN: TNMCEW

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