Co包覆Al_2O_3/TiCp复相陶瓷抗热震性能及显微结构

Thermal Shock Resistance and Microstructure of Cobalt-coated Al_2O_3/TiCp Composites

采用急冷强度法对Al2 O3 TiC Co复相陶瓷在 2 2 5～ 10 2 5℃的范围进行了抗热震性试验。结果表明 ,温差 2 0 0℃时抗弯强度下降不明显 ,温差大于 30 0℃时抗弯强度开始明显下降。通过对热震后试样的相结构及微观结构的分析发现 ,当预热温度为 10 2 5℃ (即热震温差为 10 0 0℃ )时 ,试样发生了氧化反应 ,随着热震温差的升高 ,试样的显微结构越来越疏松 ,出现了较多的孔洞 ,这是导致材料热震后强度明显下降的一个主要原因。通过 4 0 0℃热震温差的循环热震实验 ,表明随着循环次数的增加 ,抗弯强度随着下降 ,但下降的幅度将逐渐减缓。

The thermal shock resistance of Al2O3-TiC-Co composites was measured by quenching test during 225-1025°C. The experiment results show that retained strength of the composites do not greatly decline when temperature difference is 200°C and significantly decline when temperature difference is equal to or over 300°C. X-ray diffraction analysis results show that the composites are oxidized at 1025°C. SEM observation indicates that the microstructures become more and more loose and more pores emerge with the temperature difference increasing. The residual strength of the composites after thermal shock decreases significantly due to the loosened microstructure and pores formation. The cyclic thermal shock experiments were carried out for ΔT=400°C. The experiment results indicate that retained strength of the composites decline and the decreasing ranges of strength gradually weaken with thermal shock times increasing.