In this work, stainless steel blank tube and TiN-coated tube obtained by atmospheric-pressure chemical vapor deposition were used to explore the carburization during the repeated coking and decoking process. Various analytical techniques including scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Raman spectroscopy were applied to analyze the morphology, composition, and type of coke. To protect the pipeline, the on-line decoking method was used to determine the amount of coke. During the coking experiment, it was observed that carburization and metal outdiffusion occurred on the inner surface of the microchannel by scanning the cross section of reaction sheets. Moreover, the coke mass of the blank tube in the next coking experiment increased evidently after the previous coking and decoking cycle. However, under the same experimental condition, TiN coatings transforming into TiO₂–TiC_xN_y–TiN multilayer films could still maintain anticoking performance because it alleviated the carburization and metal outdiffusion.

中文翻译：

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反复炼焦过程中渗碳的研究

在这项工作中，通过大气压化学气相沉积获得的不锈钢管坯和TiN涂层管被用于探索在重复焦化和除焦过程中的渗碳。包括扫描电子显微镜，能量色散X射线光谱和拉曼光谱在内的各种分析技术被用于分析焦炭的形态，组成和类型。为了保护管道，使用在线除焦方法确定焦炭量。在焦化实验期间，通过扫描反应片的横截面观察到在微通道的内表面上发生了渗碳和金属向外扩散。此外，在之前的焦化和除焦循环之后，下一次焦化实验中的空白管的焦炭质量明显增加。然而，_2- TiC _x N _y -TiN多层膜仍可以保持抗焦化性能，因为它可以减轻渗碳和金属扩散。