乙烯作为世界上产量最大的石化原料，其生产水平和产量是评价一个国家石化行业乃至整个国家经济和科技发展水平的重要指标。乙烯裂解炉是制备乙烯的核心设备，而作为其关键部件的裂解炉管，需长时间服役于高温燃气灼烧、复杂高温活性裂解气等构成的极端环境。碳化硅基复合陶瓷是最被寄予厚望的能大幅提高裂解效率、减少结焦和清焦作业、延长服役寿命的新一代炉管材料。本项目以此为背景，针对极端服役环境下碳化硅基复合陶瓷炉管需预先突破的关键基础科学问题，开展碳化硅基复合陶瓷炉管材料在单一高温长时条件下组织性能演化规律，以及典型乙烯裂解的管外燃气流加热、管内活性裂解气环境下材料表面化学反应机理研究，并进行模拟工况下的服役寿命预测。本项目的成果可丰富极端环境下先进高温陶瓷材料服役行为方面的学术理论体系，为未来新型乙烯裂解陶瓷炉管的研发提供坚实的理论基础和有益借鉴，对推动其在化工等领域的应用具有重大意义。

Ethylene is a raw petrochemical material with the largest yield by volume in the world, and its production quality and yield are the key index for evaluating the development level of the petrochemical industry and even the overall economy, science and technology of a country. The cracking furnace is the core equipment for the production of ethylene. As its critical component, the ethylene cracking furnace tube has to bear long-term extreme conditions including exterior burning by high temperature gas, complicated interior erosion by high-temperature reactive pyrolysis gases, and etc. Silicon carbide-based ceramic composites are highly regarded as the next generation furnace tube materials to substantially improve the efficiency of ethylene cracking, reduce the burden for coking and cleaning operation, and extend the lifetime performance of furnace tubes. In this background, this project is aimed at systematically exploiting and solving the critical and fundamental scientific problems for silicon carbide-based ceramic composite tubes working under extreme conditions. Series of research would be carried out to investigate the time-dependent evolution of the microstructures and performances of silicon carbide-based ceramic composite tubes under long-term high-temperature service conditions, the mechanisms of chemical reactions occurring on both the outer skin of the tube heated by the gas and the inner skin of the tube eroded by reactive pyrolysis gases under typical conditions for ethylene cracking, and the lifetime prediction for tubes with a combination of experiment and numerical simulations. The successful accomplishment of this project would not only enrich the theoretical framework of advanced ceramic materials under extreme conditions, but also provide theoretical guidance and technical supports for the future design of novel ceramic composite tubes for ethylene cracking. Moreover, the proposed research is of significant importance in that it can facilitate the engineering applications of silicon carbide-based ceramic composite tubes in the chemical industry as well as other fields.