烧结气氛对Al_2O_3/SiC纳米复合陶瓷显微组织的影响

Effect of sintering atmosphere on microstructure of Al_2O_3 /SiC nano-composite ceramics

为了提高氧化铝陶瓷的抗热震性,将具有热导率高、热膨胀系数低的SiC加入到Al2O3中,通过无压烧结工艺,在有气氛保护和无气氛保护条件下分别制备出氧化铝基抗热震陶瓷.采用扫描电子显微镜(SEM)对陶瓷进行组织结构分析,结果表明:在气氛保护条件下烧结的Al2O3/SiC复相陶瓷气孔比无气氛条件下烧结的明显减少,复相陶瓷基体内部气孔显著降低.这样的显微组织有利于缓解热应力和提高强度,对提高陶瓷的抗热震性具有重要的作用.

In order to improve the thermal-shock resistance of alumina ceramics,nano SiC powder with high heat conductivity and low thermal-expansion coefficient was added into Al2O3 matrix. The composite ceramics with good thermal-shock resistance was prepared using pressureless sintering technology under two atmosphere conditions with and without argon gas protection. The microstructural observation of the ceramics was carried out using SEM. The experimental result indicates that the Al2O3 /SiC composite ceramics sintered in protective atmosphere contains much less porosity than one sintered in normal atmosphere,and the porosity inside the ceramic matrix gets obviously decreased. Such microstructure is advantageous in relaxing thermal stress and enhancing the strength,and plays an important role in reinforcing the thermal-shock resistance of ceramics.