含表面应力集中超高温陶瓷材料热冲击可靠性的研究

目的研究含表面应力集中的超高温陶瓷材料在热冲击环境下的可靠性。方法针对超高温陶瓷材料,研究了其威布尔分布规律和含不同切口半径的材料可靠性,并建立了其在热冲击载荷作用下的可靠性评价方法。结果对于切口不完全敏感的材料,切口件的可靠性并不是随着切口半径的减小而单调增大,对于研究的三种切口半径试样(r=0.1、0.25、0.5 mm),r=0.1 mm的试样存活率最小,r=0.25 mm的试样存活率最大。淬火初期阶段,表面含切口的材料存活率在0.04 s内急剧降低至0,0.04～0.1 s时存活率维持在0,0.1 s后存活率迅速上升,约0.28s后存活率增大为1。结论建立的评价方法可以作为超高温陶瓷材料在热冲击环境下应用可靠性的有效评估手段,对其进一步被广泛应用具有重要意义。

Thermal Shock Reliability for Ultra-high Temperature Ceramics with Stress Concentration on Surface

The work aims to investigate thermal shock reliability of ultra-high temperature ceramics with stress concentration on surface. The Weibull distribution and the reliability of ultra-high temperature ceramic materials with different notch radius were studied, and the evaluation method of reliability of ultra-high temperature ceramic materials under thermal shock load was established. For materials with incomplete notch sensitivity, the reliability of notched sample did not increase monotonously with the decrease of notch radius. For the three kinds of specimens with notch radius (r=0.1, 0.25, 0.5 mm), the survival rate of specimens with 0.1 mm notch radius was the lowest, and that of specimens with 0.25 mm notch radius was the highest. the survival rate of materials with notch on the surface in the initial stage of quenching decreased to 0 rapidly within 0.04 s, then maintained at 0 within 0.04~0.1 s and finally increased rapidly after 0.1 s and increased to 1 after 0.28 s. The established evaluation method can be used as an effective evaluation method for the application reliability of UHT ceramic materials, which is of great significance for the further application of UHT ceramic materials.