Abstract Tritium permeation barrier (TPB) coating technology is one of the most effective methods to solve the problem of permeation and leakage of tritium through the structural materials to the coolant, environment, and other functional components in tritium breeder blanket modules (TBMs). Alumina coatings prepared by in-situ oxidation of aluminized steel shows a high permeation reduced factor (PRF) and self-healing ability. However, to eliminate the Al5Fe2 phase in the aluminizing process, the stainless-steel substrate is often heat treated under high temperature conditions for a long time which leads to the degeneration of steel. In this work, a gradient alumina TPB coating was prepared on 316 L stainless steel by aluminizing process at low temperature. The influence of Al5Fe2 on the formation of Al2O3 is studied. The mechanism for the different growth behavior of Al2O3 in the polished and unpolished samples is also discussed. Compared to the polished samples, the existence of porous Al5Fe2 layer in unpolished sample changes the diffusion behavior of Al and leads to the formation of an un-continuous and rough Al2O3 layer.

中文翻译：

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渗铝不锈钢的原位氧化形成氧化铝作为氚渗透阻隔涂层

摘要 氚渗透屏障（TPB）涂层技术是解决氚通过结构材料渗透和泄漏到氚增殖毯模块（TBM）中的冷却剂、环境和其他功能部件的问题的最有效方法之一。通过对镀铝钢进行原位氧化制备的氧化铝涂层显示出高渗透降低系数 (PRF) 和自愈能力。然而，为了消除渗铝过程中的Al5Fe2相，不锈钢基体往往在高温条件下进行长时间的热处理，导致钢的变质。在这项工作中，通过低温渗铝工艺在 316 L 不锈钢上制备了梯度氧化铝 TPB 涂层。研究了Al5Fe2对Al2O3形成的影响。还讨论了抛光和未抛光样品中 Al2O3 不同生长行为的机制。与抛光样品相比，未抛光样品中多孔 Al5Fe2 层的存在改变了 Al 的扩散行为，导致形成不连续和粗糙的 Al2O3 层。