摘要
以尿素和硼酸为氮化硼源 ,利用氢气还原法在亚微米级氧化铝粉末表面均匀包覆一层纳米级BN ,包裹层的厚度可通过BN含量来调节。当氮气压力为 0 .5 2～ 0 .5 3MPa时 ,复合粉经 14 0 0℃至 160 0℃热处理 ,中间产物Al-O -B分解得到BN ,同时BN由t(turbostratic)相转变为h(hexagonal)相。 15 0 0℃处理可得到包裹紧密的h -BN -Al2 O3纳米复合粉。以氮化硅为烧结助剂 ,3 0 %BN -Al2 O3(involume)复合粉在 170 0℃热压烧结即可得到几乎完全致密化的纳米复相陶瓷 ,表观气孔率接近于零。材料的抗弯强度为 44 6MPa ,可用硬质合金钻头轻易钻孔。
Al 2O 3 powders coated with nanometer t (turbostratic)_BN were prepared through chemical processes using boric acid and urea. The t-BN coatings were turned into h-BN coatings in nitrogen environment with a pressure of 0.52-0.53 MPa by heating the nanocomposite powders up to 1 400-1 600 ℃ or by hot_pressing. The semi_finished compounds of Al-O-B reacted with N 2, and BN was obtained. With 10% Si 3N 4 (in mass) as sintering aids, the Al 2O 3/30%BN (in volume) nanocomposite powders were hot_pressed at 1 700 ℃ which was 150 ℃ lower than that without sintering aids, and the materials with almost no pore were obtained. The hot_pressed body has a high fracture strength of 446 MPa and can be drilled easily using hard alloy drill tip.
出处
《硅酸盐学报》
EI
CAS
CSCD
北大核心
2002年第4期491-495,共5页
Journal of The Chinese Ceramic Society
基金
国家自然科学基金资助项目 (5 0 0 72 0 17)~~
