摘要
研究了添加稀土氧化物热压氮化硅陶瓷及外加不同含量 Al_2O_3的热压氮化硅陶瓷的蠕变机制。前者的应力指数 n 值为1.5,显示了一种由晶界扩散和伴有空洞形成的晶界滑移同时控制的复合蠕变机制。后者视 Al_2O_3加入量不同。n 值从2.4增大至3.8,表现了一种由空洞生长引起的晶界分离所控制的蠕变机制。LaYO_3晶相从晶界玻璃相中的析出,使前者的 n 值降低至1.1,蠕变机制转为由单一的晶界扩散所控制。
The creep mechanisms of hot-pressed silicon nitride ceramics with rare-earthoxide additives without and with extra alumina in various amounts have been stu-died.Based on the stress exponent derived from the experimental result and micro-structure observation a compound mechanism of creep,or diffusional viscous flowas the controlling factor,and grain boundary sliding together with cavity forma-tion as the concurrent mechanism,is suggested for HPSN with rare-earth additives,while the grain boundary separation caused by cavitation is responsible to the HPSNwith rare-earth additives furthermore with extra alumina.LaYO_3 crystalline phasecan be separated out from the glassy phase of grain boundaries by heat treatment,and thus the stress exponent of the material drops,while the diffusional mechanismpredominates.
出处
《无机材料学报》
SCIE
EI
CAS
CSCD
北大核心
1991年第2期151-159,共9页
Journal of Inorganic Materials
关键词
氮化硅
陶瓷
稀土氧化物
蠕变
Creep
Creep mechanism
Silicon nitride
Rare-earth oxide additives
