Zr3Al3C5纳米层状化合物改性核用ZrC陶瓷的制备与性能研究

Zirconium carbide with high melting point and anti-corrosive to fission products is an important material for the next generation advanced nuclear systems. The key issues in the research field of ZrC ceramics for the application in nuclear industry mainly includes the fast sintering of ZrC ceramics at low temperature and the improvement of its mechanical reliability, thermophyscial properties and the irradiation resistance. In this project, Zr3Al3C5 ternary layered compounds with inherent weak planes is proposed to incorporate in ZrC ceramics. Vacuum evaporation will be used to realize the controllable growth of Al coating on the ZrC particles. ZrC-Al in situ reactions and reactive spark plasma sintering (R-SPS) will be adopted to decrease the sintering temperature and shorten the sintering time, and cause the homogenous formation of nanosized Zr3Al3C5 platelets in ZrC matrix. The above approaches are believed to be effective to increase the mechanical and thermophysical properties. Also, it will result in more heterointerfaces and inherent weak planes. These interfaces can trap and reflect the irradiation induced defects, and consequently improve the irradiation resistance of ZrC ceramics. Afterwards, the microstructure and properties of this material before and after irradiation test will be studied. The relationship between the microstructure and the irradiation damage of ZrC ceramics, as well as the effect of the nanosized layered interphase on the irradiation resistance of ZrC ceramics will be deeply investigated. Based on this study, we expect to provide some theoretical and experimental fundamentals for the application of ZrC ceramics in the advanced nuclear energy systems.

碳化锆（ZrC）具有熔点高、耐核裂变产物腐蚀等优点，是先进核能系统的重要候选材料。如何实现核用ZrC陶瓷的低温、快速致密化，并综合提升其力学可靠性、热物理性能和抗辐照性能，是该材料研究领域亟需解决的难点问题。本项目拟采用具有内禀弱结合面的Zr3Al3C5层状化合物改性ZrC陶瓷，利用真空蒸镀技术实现ZrC粉体表面铝（Al）包覆层的可控制备，并结合反应放电等离子体烧结法实现材料的低温、快速致密化和层状化合物在ZrC基体内的纳米级原位均匀合成，从而改善ZrC陶瓷的力学和热物理性能，并达到显著增加材料内部异质晶界和内禀弱结合面的目的。利用界面捕获、反射辐照缺陷的能力，提升材料的抗辐照性能。在此基础上，通过研究材料受辐照后微结构与性能的变化，深入剖析材料组织结构特征与其辐照损伤的内在关系，明确纳米层状界面相提升ZrC陶瓷抗辐照性能的物理机制，为该材料在先进核能系统中的应用奠定理论与实验基础。

碳化锆（ZrC）具有熔点高、耐核裂变产物腐蚀等优点，是先进核能系统的重要候选材料。项目以核用ZrC陶瓷的低温、快速致密化及其力学可靠性、抗辐照性能等协同提升为研究目标，利用自主合成的、高纯ZrC超细粉体和Al为主要原料，通过不同工艺路径制备了Zr3Al3C5层状相改性的ZrC陶瓷，并同时制备了片层状石墨改性的ZrC陶瓷、SiC颗粒改性的ZrC陶瓷，以及单相ZrC陶瓷作为对比材料。研究了ZrC1-x-Zr3Al3C5、ZrC1.0-C、ZrC1-x-SiC复相陶瓷及单相ZrC1.0陶瓷的力学性能和抗辐照性能。通过对材料相组成、显微结构的深入分析，探讨了影响层状相改性ZrC陶瓷的断裂韧性和抗辐照性能的内在因素。Zr3Al3C5层状相和材料内部原位生成的含有大量碳空位的ZrC1-x相共同作用，协同提升了ZrC陶瓷断裂韧性与抗辐照性能。进一步通过少量的Al、Si共添加，成功在1400℃的低温下实现了ZrC1-x-Zr3Al3C5-SiC陶瓷的致密化，满足了核工业领域对惰性基体燃料加工温度应低于1500℃以避免核素挥发的设计需求。在此基础上，项目又结合陶瓷领域发展前沿，通过对材料组分的高熵化设计，制备了有望展现优异抗辐照性能的(Ti0.2Zr0.2Hf0.2Nb0.2Ta0.2)C等新型陶瓷材料。项目研究成果可为ZrC陶瓷在先进核能系统中的应用奠定理论与实验基础。