摘要
本文介绍用非均相沉淀法制备的纳米SiC－Al2O3复合粉体经放电等离子超快速烧结得到晶内型的纳米复相陶瓷，超快速烧结的升温速率为600℃／min，在烧结温度不保温，迅即在3min内冷却至600℃以下．与热压烧结相比，可降低烧结温度200℃以上．力学性能研究结果表明，在1450℃超快速烧结得到的纳米复相陶瓷的抗弯强度高达1000MPa，维氏硬度为19GPa，断裂韧性也比Al2O3有所提高．TEM像显示纳米SiC颗粒大多分布在Al2O3母体晶粒内，而断裂表面的SEM像表明，穿晶断裂是其主要的断裂模式，这是所制备的纳米复相陶瓷力学性能大幅提高的主要原因．
Heterogeneous precipitation methods were used to produce 5 vol % SiC-Al2O3 nanocompositepowder, from aqueous suspension of Nano-SiC (70 nm), aqueous solution of aluminium chlorideand ammonia. The SiC-A12O3 nanocomposites were superfast densified by spark plasma sintering(SPS) process with heating to a sintering temperature range from 1350 to 1550℃, at a heatingrate of 600℃/min, without holding time, and then fast cooling to 600℃ within 2-3 minutes;and high density nanocomposites were obtained. The expermental results show that bendingstregth of 5 vol% SiC-A12O3 nanocomposites sintered at 1450℃ is as high as 1000 MPa, whileviaaers hardness about 19 GPa. fracture toughness of the sample sintered at 1500 ℃ is about 4MPa.ml/2, a little bit higher than that of A12O3 ceramics. Microstructure studies show that nanoSiC particles are mainly located in Al2O3 grains and the fracture mode of the nanocompositesis mainly transgranular fracture. Due to the eXPansion coefficient mismatch and most' of SiCparticles located in Al2O3 gains, the tensile stress, which weakens matrix grains and originates thetransgranular fracture, will appear when the samples cool down from the sintering temperature.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
1999年第1期55-60,共6页
Journal of Inorganic Materials
基金
国家攀登计划纳米材料科学项目
关键词
碳化硅
施电等离子烧结
纳米粉体
复合陶瓷
SiC nanocomposites, superfast densification, spark plasma sintering
