微观形貌调控对铀熔炼坩埚材料CaO-Y2O3-ZrO2抗热震性的影响研究

Uranium, which is highly reactive, is an important nuclear energy resource in nuclear industry. Smelting is an important step in uranium cycle because crucible performances directly affect the melting efficiency and product properties. It shows great signification that exploring suitable refractory crucible materials with high thermal shock resistance. Considering the requirements of uranium compatibility, refractoriness and thermal shock resistance, the proposal intends to employ efforts on the composition design of CaO-Y2O3-ZrO2 ternary composites, sample preparation, and to reveal the mechanism of thermal shock resistance. Investigating the thermal expansion, thermal conductivity of composite material from composition and structure. Understanding the evolution process of composition, structure and properties during the cycle thermal shock. Emphasizing the effect of microstructure modulation for thermal shock resistance of composite materials. Based on classical thermal shock theory, deriving the mechanism of crack formation and propagation. To establish a model of thermal shock resistance in CaO-Y2O3-ZrO2 ternary composites with practical value.

铀是核工业中的重要核能资源，其化学性质活泼。熔炼是铀循环周期中的重要步骤，坩埚性能直接影响熔炼效率及成品性能，因此探索抗热震性良好，耐高温的坩埚材料具有重要意义。综合考虑坩埚材料与铀的相容性、耐火度及抗热震性的要求，本项目拟开展CaO-Y2O3-ZrO2三元复合材料的成分设计、制备及其抗热震性机理研究。探索复合材料的成分、结构对热膨胀系数、热导率等性能的影响。掌握循环热冲击过程中成分、结构和性能的演化，重点关注微观形貌调控对复合材料抗热震性的影响。结合已有的热震理论，获得裂纹形成、扩展的机制，建立较具实用价值的CaO-Y2O3-ZrO2复合材料的抗热震性模型。

针对铀熔炼应用需求，本项目从典型的坩埚材料CaO着手，选择了与铀具有良好的相容性的Y2O3作为主复合相，并探索了ZrO2对复合材料性能的影响。CaO-Y2O3-ZrO2复合陶瓷采用固相烧结法制备，结合成分设计对其微观形貌、烧结特性、水化抗性和力学性能进行了调控，并开展了抗热震性分析。结果表明Y2O3将与CaO形成两相结构，且陶瓷微观形貌随Y含量变化而发生改变。适量Y2O3可以实现CaO陶瓷的晶界强化，提高其水化抗性和力学性能，同时有助于改善材料的抗热震性。而引入ZrO2将导致CaZrO3和Ca-Y-O复合物的生成，使得复合陶瓷的致密度降低，整体性能有所劣化。总体而言，基于优化的成分设计，CaO基复合陶瓷展现出了良好的抗热震性，有望成为一种良好的金属熔炼用坩埚材料。