Faculty of Science and Technology, Energy and Resources Institute, Advanced Manufacturing Alliance, Charles Darwin University, Darwin, Northern Territory, Australia.
PLoS One. 2024 Aug 20;19(8):e0306164. doi: 10.1371/journal.pone.0306164. eCollection 2024.
Microbiologically Influenced Corrosion (MIC) poses a significant challenge to various industries, leading to substantial economic losses and potential safety hazards. Despite extensive research on the MIC resistance of various materials, there is a lack of studies focusing on High Chromium White Iron (HCWI) alloys, which are widely used in wear-resistant applications. This study addresses this knowledge gap by providing a comprehensive investigation of the MIC resistance of three HCWI alloys with varying chromium contents (22 wt%, 30.7 wt%, and 21 wt%) in the presence of Pseudomonas aeruginosa (P. Aeruginosa), a common bacterial species associated with MIC. The alloys were exposed to an artificial seawater medium inoculated with P.Aeruginosa for 14 days, and their corrosion behaviour was evaluated using electrochemical techniques, surface analysis, and microscopy. Electrochemical Impedance Spectroscopy (EIS) results revealed that the alloy with the highest chromium content (A2, 30.7 wt% Cr) exhibited superior MIC resistance compared to the other alloys (A1, 22 wt% Cr and M1, 21 wt% Cr). The enhanced performance of alloy A2 was attributed to the formation of a more stable and protective passive film, as well as the development of a more compact and less permeable biofilm. The EIS data, interpreted using equivalent circuit models, showed that alloy A2 had the highest charge transfer resistance and the lowest biofilm capacitance, indicating a more effective barrier against corrosive species. Bode plots further confirmed the superior corrosion resistance of alloy A2, with higher impedance values and phase angles at low frequencies compared to alloys A1 and M1. Scanning Electron Microscopy (SEM) and optical microscopy analyses corroborated these findings, showing that alloy A2 had the lowest pit density and size after 14 days of exposure. The insights gained from this study highlight the critical role of chromium content in the MIC resistance of HCWI alloys and have significant implications for the design and selection of materials for applications prone to microbial corrosion.
微生物影响腐蚀 (MIC) 对各种行业构成重大挑战，导致重大经济损失和潜在安全隐患。尽管对各种材料的 MIC 抗性进行了广泛研究，但缺乏针对高铬白口铁 (HCWI) 合金的研究，而这些合金广泛用于耐磨应用。本研究通过全面调查三种具有不同铬含量（22wt%、30.7wt%和 21wt%）的 HCWI 合金在铜绿假单胞菌 (P. Aeruginosa) 存在下的 MIC 抗性来填补这一知识空白，铜绿假单胞菌是一种与 MIC 相关的常见细菌。将合金暴露于接种有 P.Aeruginosa 的人工海水介质中 14 天，并使用电化学技术、表面分析和显微镜评估其腐蚀行为。电化学阻抗谱 (EIS) 结果表明，铬含量最高的合金（A2，30.7wt%Cr）与其他合金（A1，22wt%Cr 和 M1，21wt%Cr）相比，表现出优异的 MIC 抗性。合金 A2 的优异性能归因于更稳定和保护性的钝化膜的形成，以及更致密和更不易渗透的生物膜的发展。使用等效电路模型解释 EIS 数据表明，合金 A2 具有最高的电荷转移电阻和最低的生物膜电容，表明其对腐蚀性物质具有更有效的阻挡作用。Bode 图进一步证实了合金 A2 的卓越耐腐蚀性，与合金 A1 和 M1 相比，其在低频下具有更高的阻抗值和相位角。扫描电子显微镜 (SEM) 和光学显微镜分析证实了这一发现，表明合金 A2 在暴露 14 天后具有最低的点蚀密度和尺寸。本研究的结果突出了铬含量在 HCWI 合金 MIC 抗性中的关键作用，对设计和选择易受微生物腐蚀影响的应用材料具有重要意义。
