Lei Peng, Zhou Lizhen, Zhang Yu, Wang Fuli, Li Qinzhe, Liu Jiangyan, Xiang Xueyun, Wu Hang, Wang Wen, Wang Fuhui
Shenyang National Laboratory for Materials Science, Northeastern University, Shenyang 110819, China.
School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China.
Materials (Basel). 2024 May 14;17(10):2335. doi: 10.3390/ma17102335.
This study investigates the corrosion behavior of Ni-Cr binary alloys, including Ni-10Cr, Ni-15Cr, Ni-20Cr, Ni-25Cr, and Ni-30Cr, in a NaCl-KCl-MgCl molten salt mixture through gravimetric analysis. Corrosion tests were conducted at 700 °C, with the maximum immersion time reaching up to 100 h. The corrosion rate was determined by measuring the mass loss of the specimens at various time intervals. Verifying corrosion rates by combining mass loss results with the determination of element dissolution in molten salts using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). Detailed examinations of the corrosion products and morphology were conducted using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Micro-area elemental analysis on the corroded surfaces was performed using an energy dispersive spectrometer (EDS), and the elemental distribution across the corrosion cross-sections was mapped. The results indicate that alloys with lower Cr content exhibit superior corrosion resistance in the NaCl-KCl-MgCl molten salt under an argon atmosphere compared to those with higher Cr content; no corrosion products were retained on the surfaces of the lower Cr alloys (Ni-10Cr, Ni-15Cr). For the higher Cr alloys (Ni-20Cr, Ni-25Cr, Ni-30Cr), after 20 h of corrosion, a protective layer was observed in certain areas. The formation of a stable CrO layer in the initial stages of corrosion for high-Cr content alloys, which reacts with MgO in the molten salt to form a stable MgCrO spinel structure, provides additional protection for the alloys. However, over time, even under argon protection, the MgCrO protective layer gradually degrades due to chloride ion infiltration and chemical reactions at high temperatures. Further analysis revealed that chloride ions play a pivotal role in the corrosion process, not only facilitating the destruction of the CrO layer on the alloy surfaces but also possibly accelerating the corrosion of the metallic matrix through electrochemical reactions. In conclusion, the corrosion behavior of Ni-Cr alloys in the NaCl-KCl-MgCl molten salt environment is influenced by a combination of factors, including Cr content, chloride ion activity, and the formation and degradation of protective layers. This study not only provides new insights into the corrosion resistance of Ni-Cr alloys in high-temperature molten salt environments but also offers significant theoretical support for the design and optimization of corrosion-resistant alloy materials.
本研究通过重量分析研究了Ni-10Cr、Ni-15Cr、Ni-20Cr、Ni-25Cr和Ni-30Cr等Ni-Cr二元合金在NaCl-KCl-MgCl熔盐混合物中的腐蚀行为。腐蚀试验在700℃下进行，最大浸泡时间长达100小时。通过测量不同时间间隔下试样的质量损失来确定腐蚀速率。通过将质量损失结果与使用电感耦合等离子体发射光谱法（ICP-OES）测定熔盐中元素溶解相结合来验证腐蚀速率。使用X射线衍射（XRD）和扫描电子显微镜（SEM）对腐蚀产物和形态进行了详细检查。使用能量色散光谱仪（EDS）对腐蚀表面进行微区元素分析，并绘制了腐蚀横截面的元素分布图。结果表明，与高Cr含量合金相比，低Cr含量合金在氩气气氛下的NaCl-KCl-MgCl熔盐中表现出更好的耐腐蚀性；低Cr合金（Ni-10Cr、Ni-15Cr）表面没有残留腐蚀产物。对于高Cr合金（Ni-20Cr、Ni-25Cr、Ni-30Cr），腐蚀20小时后，在某些区域观察到了一层保护层。高Cr含量合金在腐蚀初期形成稳定的CrO层，该层与熔盐中的MgO反应形成稳定的MgCrO尖晶石结构，为合金提供了额外的保护。然而，随着时间的推移，即使在氩气保护下，MgCrO保护层也会由于氯离子渗透和高温下的化学反应而逐渐降解。进一步分析表明，氯离子在腐蚀过程中起着关键作用，不仅促进了合金表面CrO层的破坏，还可能通过电化学反应加速金属基体的腐蚀。总之，Ni-Cr合金在NaCl-KCl-MgCl熔盐环境中的腐蚀行为受多种因素综合影响，包括Cr含量、氯离子活性以及保护层的形成和降解。本研究不仅为Ni-Cr合金在高温熔盐环境中的耐腐蚀性提供了新的见解，也为耐腐蚀合金材料的设计和优化提供了重要的理论支持。
