Understanding the corrosion mechanism of iron artifacts using Mössbauer spectroscopy

Iron artifacts undergo complex corrosion processes, depending on the burial environment. Understanding the formation mechanism of corrosion products is crucial for preservation of artifacts and helps design strategies for future iron artifacts protection. Mössbauer spectroscopy was primarily utilized in this work to analyze the corrosion products formed on iron artifacts. The corrosion products were identified as consisting of goethite, lepidocrocite, magnetite, and maghemite. Low-temperature Mössbauer spectroscopy was performed for the accurate identification and quantitative analysis of superparamagnetic iron corrosion products. The results indicated that the surface corrosion products mainly consist of goethite and superparamagnetic goethite, with small amounts of lepidocrocite, magnetite, and/or maghemite. A cross-sectional analysis of the corrosion layers on an artifact was performed to better understand the corrosion products and their formation mechanisms. The products formed in different sections (metal, intermediate, and surface) of the corrosion layers on the iron artifact were identified, and a corrosion mechanism was proposed. The intermediate layer adjacent to the metal contains magnetite, maghemite, and lepidocrocite. The results presented in this study provide a deeper understanding of the iron corrosion process, laying a solid foundation for the development of an effective strategy for preserving iron artifacts.