Abstract: An anti-coking oxide film was prepared by a low oxygen partial pressure method for inner surface of cracking tube in service. The morphologies, composition and structure of the inner surface, the adhesion between the oxide film and the substrate and the anti-coking performance of the specimen were characterized by SEM, EDAX, X-ray diffraction, scratch tester. The results show that Fe and Ni content decreases after the process of low oxygen partial pressure. The oxide film is mainly composed of MnCr₂O₄ and Cr₂O₃ and the critical load between oxide films and substrates is 9.25 N. The anti-coking ratio reaches 69.92%, it proves that the oxide films can prevent catalytic filament cokes from deposition effectively.

Key words: Cracking tube in service, Low oxygen partial pressure, Oxide film, Anti-coking

摘要： 利用低氧分压法在已服役炉管的内表面制备防结焦氧化膜。用扫描电子显微镜（SEM）、能谱仪（EDAX）、X射线衍射仪（XRD）及划痕仪等实验手段，研究已服役炉管及氧化膜的形貌、组织结构、氧化膜与基体结合状况及氧化膜的抗结焦性能。结果表明，经过低氧分压处理后，已服役炉管试样表面的Fe，Ni元素含量降低，表面形成了以MnCr₂O₄和Cr₂O₃为主的氧化膜，氧化膜的临界载荷为9.25 N，结焦抑制率达到69.92%，具有明显的防催化结焦效果。

关键词: 已服役炉管 , 低氧分压 , 氧化膜 , 防结焦