升温热冲击环境下超高温陶瓷材料抗热震性能的热-损伤模型

A thermo-damage-dependent thermal shock resistance model for ultrahigh temperature ceramics for temperature rising thermal shock environment

在现有的抗热震理论基础上考虑到超高温陶瓷材料热物理性能对温度的敏感性及损伤在其使役历程中随温度的演化,建立了适用于升温服役环境下表征超高温陶瓷材料抗热震性能的热-损伤模型。该模型考虑了微裂纹尺寸、密度、热冲击环境温度等因素对材料抗热震性能的影响。利用此模型研究了超高温陶瓷材料在升温服役环境下损伤以微裂纹形核规律演化时对其抗热震性能的影响。从理论上验证了基于材料微结构设计思想在制备超高温陶瓷材料时,引进一定密度一定尺寸的微裂纹并控制其随温度演化规律以形核方式进行,既可以使材料保持较高的强度又能大幅度提升材料的抗热震性能。

A thermo-damage-dependent thermal shock resistance(TSR) model,which takes into account the sensitivities of thermo-physical properties to temperature and the evolution of the mechanisms of strength of ultra-high temperature ceramics(UHTCs) at elevated temperature is established.The model incorporates the effects of micro-crack size,density,damage evolution,and temperature on TSR of UHTCs.A detailed study about the effects of damage and its different nucleation laws on thermal shock performance of UHTCs is made by using this model.Results obtained show that through material microstructure design to introduce micro-cracks of a certain density and length into UHTCs while manufacturing and control damage evolution as the nucleation mode,not only the high strength of UHTCs can be kept,but also its TSR can be improved enormously.