Use of FTIR for the Quantitative Study of Corrosion Products of Iron Cultural Relics

Iron cultural relics are an important cultural heritage of humanity and are of great significance for studying the development and progress of human society. Conservators protect such cultural relics as much as possible to provide valuable physical materials for historical and cultural research. The characteristics of iron with high activity and easy corrosion make iron cultural relics one of the difficulties in conserving metal cultural relics. There are many studies on the protection and restoration of iron cultural relics and the qualitative analysis of iron rust products, while there are relatively few studies on the quantitative characterization of iron rust products. Furthermore, the complexity of corrosion products also increases the difficulty of quantitative analysis. In order to understand the composition of iron cultural relics rust products and evaluate their stability, it is necessary to establish a method for quantitative analysis of the rust products of iron cultural relics. In this study, five rust products (alpha-Fe2O3 Fe3O4, alpha-FeOOH, beta-FeOOH gamma-FeOOH) were used to simulate samples (three groups of binary mixture systems and a set of quaternary mixture systems) of iron artifacts. Infrared spectroscopy combined with the Classical Least Squares (CLS), Principal Components Regression (PCR) and Partial Least Squares (PLS) in TQ Analyst software was used to construct quantitative analysis models of four groups of mixtures, respectively. The results show that PCR and PLS are more suitable for establishing quantitative models of rust products of iron cultural relics among the three quantitative analysis models. Moreover, the root mean squared error of calibration (RMSEC) and root mean squared error of prediction (RMSEP) are small, and the correlation coefficient is close to 1. The quantitative models have good predictability and stability. The research results provide a basis for the quantitative analysis of the rust products of iron cultural relics and then the evaluation of the chemical stability of iron cultural relics.