超高温陶瓷热冲击损伤演化的同步辐射研究

Abstract: Thermal shock resistance is one of the most critical issues for ZrB2-SiC unltra-high temperature ceramics applied in hypersonic aircraft. However, the thermal shock resistance of ZrB2-SiC is poor resulting from its inherent brittleness. In the present work, an in situ investigation has been carried out on the damage evolution of ZrB2-SiC unltra-high temperature ceramics subjected to thermal shock by means of synchrotron radiation approach. A miniaturization instrument for thermal shock based on synchrotron radiation will be designed. Real-time, in situ observations on the thermal shock crack evolution inside the ceramics will be carried out. In order to realize optimization design, the effect of microscopic structure on the high thermal shock resistance both are studied and investigated. This proposed project aims on the critical issues of the ultra-high temperature ceramics and is expected to provide a technical guidance for the research and development of hypersonic aircraft.

抗热冲击性能是ZrB2-SiC超高温陶瓷应用于高超声速飞行器亟需解决的关键指标之一。由于ZrB2-SiC超高温陶瓷的固有脆性，导致其抗热冲击性能较差。本项目针对ZrB2-SiC系列超高温陶瓷，设计和研制基于同步辐射光源的小型热冲击加载平台，实时、在位观测热冲击作用下超高温陶瓷内部的裂纹演化，探讨超高温陶瓷的微观结构对其抗热冲击性能的影响机制，以实现具有高抗热冲击性能的材料微结构优化设计，为我国高超声速飞行器的发展提供技术指导。

针对典型的工程陶瓷Al2O3和超高温陶瓷材料ZrB2-SiC，采用水淬方式，系统开展了陶瓷的热冲击实验，给出了热冲击裂纹的定量表征方法，研究了结构特征尺寸、换热方式、介质温度等因素对陶瓷热冲击性能的影响。结合理论分析，探讨了径向厚度对临界热震温差的影响机制，提出了具有高抗热震性能圆/圆环形陶瓷构件的结构优化设计和换热方式选取方案，为陶瓷构件在高温环境中安全服役提供指导。基于陶瓷热震裂纹演化的统计细观损伤模型，通过对比分析热震裂纹终态特征反演陶瓷热震过程中的换热系数，获得了换热系数随介质温度和热震温差的变化规律，探讨了介质温度和热震温差对陶瓷热震性能的影响机制。.