Abstract Corrosion behaviors of 316 stainless steel (316 ss) and Inconel 625 alloy in molten NaCl–KCl–ZnCl2 at 700°C and 900°C were investigated by immersion tests and electrochemical methods, including potentiodynamic polarization and electrochemical impedance spectroscopy. X-ray diffraction and scanning electron microscopy/energy dispersive spectroscopy were used to analyze the phases and microstructures of the corrosion products. Inconel 625 alloy and 316 ss exhibited high corrosion rates in molten chlorides, and the corrosion rates of these two alloys accelerated when the temperature increased from 700°C to 900°C. The results of the electrochemical tests showed that both alloys exhibited active corrosion in chloride molten salt, and the current density of 316 ss in chloride molten salt at 700°C was 2.756 mA/cm−2, which is about three times the value for Inconel 625 alloy; and the values of the charge transfer resistance (R t) for Inconel 625 were larger than those for 316 ss. The corrosion of these two alloys is owing to the preferred oxidation of Cr in chloride molten salt, and the corrosion layer was mainly ZnCr2O4 which was loose and porous and showed poor adherence to metal.

中文翻译：

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316不锈钢和Inconel 625合金在太阳能储能氯化物熔盐中的腐蚀行为

摘要 通过浸泡试验和电化学方法，包括动电位极化和电化学阻抗谱，研究了 316 不锈钢（316 ss）和 Inconel 625 合金在 700°C 和 900°C 熔融 NaCl-KCl-ZnCl2 中的腐蚀行为。X射线衍射和扫描电子显微镜/能量色散光谱用于分析腐蚀产物的相和微观结构。Inconel 625 合金和 316 ss 在熔融氯化物中表现出较高的腐蚀速率，当温度从 700°C 升高到 900°C 时，这两种合金的腐蚀速率加快。电化学测试结果表明，两种合金在氯化物熔盐中均表现出活性腐蚀，700℃氯化物熔盐中316 ss的电流密度为2.756 mA/cm-2，大约是 Inconel 625 合金价值的三倍；Inconel 625 的电荷转移电阻 (R t) 值大于 316 ss 的值。这两种合金的腐蚀是由于Cr在氯化物熔盐中的优先氧化，腐蚀层主要是疏松多孔的ZnCr2O4，对金属的附着力差。