Corrosion Science 255 (2025) 113073
Enhancing corrosion resistance of Ti2AlC MAX phase through Sn solid solution in harsh acidic environments
Jiayue Zhang#,Yan Zhang#, Zhenyu Wang, Guanshui Ma*, Anfeng Zhang, Kwang-Ryeol Lee, Aiying Wang*
When proton exchange membrane fuel cells (PEMFCs) run in the harsh acidic environment at 60-80 ℃, metallic bipolar plates are prone to dissolution and corrosion, leading to increased interfacial contact resistance (ICR) and a decrease in output power energy. In this work, high-purity Ti2AlC MAX phase coatings, with and without Sn solid solution, were fabricated on 316 L stainless steel using a multiple sputtering technique followed by a subsequent heat treatment process. Effect of Sn modification on the corrosion resistance and electrical conductivity of coatings was particularly focused on under simulated PEMFCs conditions. The results indicated that the Ti2(Al, Sn)C coating significantly improved electrical conductivity and corrosion resistance compared to the pristine Ti2AlC coating. The observed phenomena in Ti2(Al, Sn)C coating could be attributed to the unique appearance of passivation layer, where three layers—TiO2, Al2O3 and SnO2— were identified distinctly. One benefit was that the outermost SnO2, resulting from the oxidation of Sn, partially inhibited the penetration of corrosive media. This enhancement improved the protective efficiency of the subsequent Al2O3 layer, which has a higher density than that of TiO2 layer. On the other hand, the microstructure evolution of the passivation film was also well consistent with the capability of atomic diffusion, as indicated by the atomic vacancy formation energy and the migration energy by density functional theory simulation. As a result, the unusual layered oxides in the Ti2(Al, Sn)C coating enhanced the corrosion resistance and ICR value of the coatings compared to the pristine Ti2AlC coating.
URL：https://doi.org/10.1016/j.corsci.2025.11307
AI解读进展：
一、研究背景
质子交换膜燃料电池（PEMFC）在 60–80 ℃ 的酸性环境下运行，金属双极板易发生溶解与腐蚀，导致界面接触电阻（ICR）升高和功率衰减。MAX 相涂层因兼具金属导电性与陶瓷稳定性被视为潜在候选，但其在强酸环境下形成的钝化膜结构与防护效率仍有待提升。本工作提出了一种通过元素固溶调控 MAX 相氧化行为与钝化结构的新策略，为 PEMFC 金属双极板防护涂层的设计提供了新解决思路，也为多层功能协同钝化膜的构筑及其原子尺度调控机理研究提供了重要参考。
二、创新思路
本研究通过 Sn 元素固溶调控 Ti₂AlC MAX 相涂层的氧化与钝化行为，在不牺牲电导性的前提下，主动构建多层协同防护的钝化结构，从材料设计层面破解金属双极板“耐蚀性–低 ICR”难以兼顾的关键难题。相比“单纯提高致密度或厚度”的常规思路，本工作通过元素固溶调控氧化行为实现“高耐蚀性 + 低 ICR”兼顾性能提升，路径新颖。
三、研究结果
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成功制备 Sn 固溶的 Ti₂(Al,Sn)C 高纯 MAX 相涂层，并在 PEMFC 模拟工况下表现出显著优于 Ti₂AlC 的耐蚀性和更低的 ICR；
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与传统 Ti₂AlC 主要形成 TiO₂/Al₂O₃ 混合氧化层不同，首次发现Ti₂(Al,Sn)C 涂层表面形成了SnO₂/Al₂O₃/TiO₂ 三层分离的钝化膜结构，其中外层 SnO₂ 抑制腐蚀介质渗透，中间致密 Al₂O₃ 层提供主要防护；
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结合第一性原理计算，从原子空位形成能和迁移能垒角度，分析了Sn、Al、Ti 原子扩散顺序对氧化动力学影响规律，揭示了Sn固溶诱导“分层钝化膜“的形成机理，与实验结果高度一致。
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