ZrB2-SiC基超高温陶瓷材料的强韧化与热冲击行为研究

The low damage tolerance and poor resistance to thermal shock performance of ultra-high temperature ceramics (UHTCs) have become the fatal weaknesses which restrict their excellent combined high temperature performance to engineering applications. This project focuses on strengthening-toughening mechanism and thermal shock behavior of ZrB2-SiC-based ultra-high temperature ceramics. The coupled mechanisms among microstructure, thermal-physical properties , thermal load and thermal shock resistance will be clarified by combinedly using the theoretical analysis, numerical simulation, experimental design and verification methods. The main controlling parameters impacting the thermal shock resistance of ultra-high temperature ceramics will be investigated to establish the scientific characterization and evaluation of thermal shock resistance for UHTCs. Ultra-high temperature ceramics having high damage tolerance and excellent thermal shock resistance will be obtained by optimizing materials microstructure and processing. The goals of this project are to make a breakthrough in the basic theory and experimental innovation of the thermal shock resistance for UHTCs and to gain the design, fabrication and performance evaluation of the new kind of UHTCs with high reliability and excellent comprehensive properties, which provies a theoretical basis and implementation for the strengthening/toughening and engineering applications of ultra-high temperature ceramics.

超高温陶瓷材料较低的损伤容限和较差的抗热冲击性能制约了其优异的高温综合性能的发挥和工程的应用，本项目重点研究ZrB2-SiC基超高温陶瓷材料的强韧化与热冲击行为，采用理论推导、数值模拟、实验设计与验证相结合的方法，探明材料微结构、热物性参量、载荷加载条件与热冲击性能之间的耦合响应机理，揭示影响超高温陶瓷材料热冲击性能主要控制参量，建立科学的超高温陶瓷材料热冲击性能表征与评价方法，优化出具有损伤容限高、热冲击性能优异的超高温陶瓷材料的微结构设计与制备方法，力求在超高温陶瓷材料抗热冲击的基础理论和实验创新上有所突破，最终实现可靠性高、综合性能优异的新型超高温陶瓷材料的设计、制备和性能评价，为超高温陶瓷材料的强韧化和工程应用提供理论依据和实现方法。

本课题以高超声速飞行器、空天飞机、可重复使用跨大气层飞行器关键热端部件对超高温陶瓷材料的需求为背景，针对超高温陶瓷材料较低的损伤容限和较差的抗热冲击性能这一技术瓶颈，开展了超高温陶瓷材料抗热冲击性能的表征与评价和超高温陶瓷的新型强韧化方法方面的研究。通过2013至2015年三年的实验和基础理论研究，揭示了热物理参量、微结构和尺寸效应对超高温陶瓷材料热冲击性能的影响规律，建立了超高温陶瓷材料抗热冲击性能表征与评价方法；获得了粉体粒径、烧结温度以及烧结工艺对纳米ZrB2基超高温陶瓷材料烧结性能的影响规律，实现了纳米超高温陶瓷材料低温致密化及微结构精确控制；采用纳米粉体制备了碳纤维增韧超高温陶瓷复合材料，解决了碳纤维性能退化的难题，显著提高了超高温陶瓷材料的破坏应变，阐明了该材料的强韧化机制，为提升超高温陶瓷的损伤容限和抗热冲击性能提供了一种崭新的途径；阐明了碳纤维增韧超高温陶瓷复合材料的热冲击和抗氧化行为，获得了综合性能优异的超高温陶瓷材料，为该材料在航空航天领域的工程应用提供了理论和技术支撑。