Environmental effects on slow crack growth in silicon nitride. [Effects of sodium sulfate at 1573)sup 0)K]

摘要: Slow crack growth measurements are being conducted to determine velocity versus stress intensity as a function of chemical environment in advanced ceramic materials. Controlled, artificial flaws placed the flat tensile faces hot pressed Si/sub 3/N/sub 4/ specimens (2.3 x 2.3 21.6 mm gage) and oriented open mode I on loading. Tests have been performed air without coating sodium sulfate at 1573/sup 0/K. results indicate that slow presence is about twice fast air. 5 refs., figs