ZrB_2-20%SiC超高温陶瓷抗热震性能研究

The Thermal Shock Resistance of ZrB_2-SiC Ultra-high Temperature Ceramics

采用放电等离子烧结工艺在1850℃烧结温度、升温速度200℃/min、保温3min、压力50MPa条件下制备了ZrB_2-20%SiC(体积分数,下同)超高温陶瓷材料。通过不同温度下单次和5次重复热震(水淬试验)后测试材料的残余强度来评价ZrB_2-SiC陶瓷材料的抗热震性能,通过SEM分析研究材料的热震损伤机制。研究结果表明,随着热震温度的提高,ZrB_2-SiC材料热震后的残余强度逐渐降低,但1400℃热震后形成的玻璃相,对裂纹有修补、愈合的作用,提高了试样的残余强度。单次热震的损伤机制主要是微裂纹的产生。5次热震后试样的残余强度与相同温度下的单次热震相比要低很多,5次热震的损伤机制是氧化和微裂纹的共同作用。ZrB_2-SiC材料的抗热震试验结果显示了该材料具有优异的抗热震性能。

ZrB2-20vol.%SiC ultra-high temperature ceramics were prepared by spark plasma sintering technique （SPS）. The thermal shock experiments were tested by water quenching for one time and five times. The residual bending strength of the samples was tested at different temperatures of thermal shock. The thermal shock resistance of ZrB2-20vol.%SiC ceramics was characterized. The microstructure of the samples was examined by SEM and the thermal shock damage mechanism of the material was analyzed. The results showed that with the increase of the temperature of thermal shock, the residual strength ofthe samples after thermal shock decreased. After thermal shock at 1400℃, the glass inclusions formed were found to heal the cracks and led to the increase of the residual strength of the samples. The thermal shock damage mechanism of the material for one time thermal shock was appearance of cracks. The residual bending strength of the samples after thermal shock for five times was much lower than that of the thermal shocked samples for one time. The thermal shock damage mechanism of the material for five-time thermal shock was coaction of cracks and oxidation.