热处理对无压烧结氮化硅的显微结构与强度的影响

THE EFFECT OF HEAT TREATMENT ON MICROSTRUCTURE AND STRENGTH OF PRESSURELESS SINTERED Si_3N_4

系统地研究了添加MgO·Al_2O_3和ZrO_2的无压烧结氮化硅经热处理后显微结构与强度的变化。结果表明:试样在纯净的氮气气氛中热处理时,晶界玻璃相中可析出堇青石晶体和顽火辉石晶体;热处理后的试样常温抗折强度有所降低而高温抗折强度大大提高。

Microstructure change and strength of pressureless sintered Si_3N_4 added with MgO·Al_2O_3 and ZrO_2 after heat-treatment are studied systematically. Theresults show that when samples are subject to heat treatment in pure N_2 gas, cordierite and enstatite can be separated from the grain boundary glass phases. The bending strength of crystallized samples is somewhat reduced at room temperature, but greatly increased at high temperature.