基于楔形劈裂法与有限元模拟的轻量方镁石-镁铝尖晶石耐火材料损伤演化及断裂机理研究

The lightweighting of refractory materials, which are used as the lining of high temperature furnaces, is effective for achieving the energy conservation and emission reduction of the high energy consumption industries, such as the steel, cement and petrochemical industries. However, the fracture mechanism and damage evolution of lightweight refractories are unrevealed as they are served under the high temperature and complex environment. In this project, the evolution of full-field strain and fracture behaviour of typical lightweight periclase-MA spinel refractory are investigated by wedge splitting test combining the digital image correlation technique. Firstly, the influence of the properties of lightweight aggregates (i.e. phase composition, content and pores structure) and the lightweight aggregate-matrix interface on the fracture behaviour are illustrated. The methods for improving the high temperature mechanical properties are proposed based on the amelioration of the physico-chemical conditions for the preparation of lightweight aggregates. Furthermore, the continuous heterogeneous FE model is built according to the high heterogeneity and the complex interface properties for realistically simulating the damage evolution under the high temperature and cyclic thermo-mechanical stress, and for revealing the fracture mechanism of lightweight refractories. Finally, a system for evaluating the fracture behaviour of lightweight refractory is established, which will contribute to the optimization and development of high-performance lightweight refractories, both for the periclase-MA spinel refractory and other types of lightweight refractory.

高温窑炉内衬耐火材料轻量化是实现钢铁、水泥及石化等高耗能行业节能减排的重要途径。针对轻量耐火材料在高温复杂服役环境下损伤演化难以定量直观研究，造成断裂机理不明的问题，本项目以典型的轻量方镁石-镁铝尖晶石耐火材料为研究对象，采用楔形劈裂法结合数字图像相关技术，研究耐火材料在载荷条件下的全场应变过程及断裂行为，揭示轻量骨料种类（物相组成、含量和孔结构）、轻量骨料-基质界面特性等微结构参数对材料断裂行为的影响规律；并通过优化制备轻量化骨料的物理化学条件，探明提高轻量耐火材料高温力学性能的有效途径；在此基础上，建立符合轻量耐火材料高异质性和复杂界面特征的有限元模型，真实模拟其在高温服役过程中冷热循环及载荷条件下的细观损伤演化，揭示材料断裂机理，最后建立轻量耐火材料断裂行为评价体系，为开发高强兼具高热震稳定性的新一代轻量方镁石-镁铝尖晶石质耐火材料奠定理论基础，也为开发其他轻量耐火材料提供理论指导。

高温窑炉内衬耐火材料轻量化是实现高耗能行业节能减排的重要途径。项目通过探究高温复杂服役环境下轻量耐火材料的损毁行为及强韧化机理，明确高强兼具高热震稳定性的轻量方镁石-尖晶石质耐火材料的开发路径。主要研究成果如下: 1）采用可控原位分解技术和组分调控，制备了不同气孔率的轻量陶瓷骨料及耐火材料。通过与致密材料相比，探明了孔径分布、物相组成等对轻量骨料裂纹弥散以及骨料-基质界面结合增强的作用机理。2）结合原位数字图像相关性以及断裂路径后分析方法，构建了轻量方镁石-镁铝尖晶石耐火材料细观断裂过程与宏观力学性能的相关性，探明骨料轻量化对裂纹路径的引导机理，揭示了轻量耐火材料增强机制。3）制备了核壳结构方镁石-镁铝尖晶石复合骨料及相应耐火材料，结合前两个内容实现了方镁石-镁铝尖晶石耐火材料骨料-基质-界面一体化调控依据。4）采用多尺度框架非均质模拟策略，建立了相应多组分仿真材料模型，探明了轻量化对能量耗散过程的影响机制，明确了轻量方镁石-镁铝尖晶石耐火材料在热-机械载荷条件下的断裂过程区发展以及决定因素。上述研究成果对于建立轻量耐火材料高温力学性能评价体系，开发新一代轻量方镁石-镁铝尖晶石耐火材料，不断满足高温工业节能减排要求具有重要的意义。