摘要
对氮化硅结合碳化硅耐火材料 (SNBSC)表面等离子喷涂莫来石涂层的热震性能和相变过程进行了研究 ,结果表明仅一次高温热震 (>1 0 0 0℃ )莫来石涂层中就产生微细裂纹。物相分析表明等离子喷涂莫来石涂层由玻璃相、γ- Al2 O3、亚稳的四方相 (2∶ 1 )莫来石组成。在室温 1 30 0℃热震过程中 ,这些亚稳相转变成稳定的 (3∶ 2 )莫来石和 α- Al2 O3,同时也有少量的方石英析出。玻璃相在加热过程中的结晶导致体积发生收缩 ,这是涂层产生裂纹的关键原因。
The thermal shock resistance and phase transformation in mullite coating on Silicon Nitride Bonded Silicon Carbide Refractory (SNBSC) were studied. Results show that micro-cracks emerged after only one time of thermal shock above 1 000 ℃. XRD results indicate that plasma sprayed mullite coating consists of glass, α-Al 2O 3 and metastable (2∶1) mullite. When heated to 1 300 ℃, these metastable phases transformed into stable (3∶2) mullite,α-Al 2O 3 and cristobalite. The crystallization of glass, which is accompanied with volume shrinkage, is the main reason of these micro-cracks induced in the coating.
基金
国家自然科学基金资助 !(5960 2 0 0 8)
关键词
莫来石
等离子喷涂
相变
涂层
mullite
\ plasma spraying
\ phase transformation