The oxidation characterization and thermostability was studied using X-ray diffraction, Raman analysis and thermo gravimetric-differential scanning calorimetric analysis(TG-DSC). Controlled oxidation experiments were conducted for 30mins, 1hour and 4 hours. S-species were characterized and qualified on surface of corrosion particle combine XRD with Raman analysis. Mackinawite FeS transforms into greigite Fe3S4 readily with additional S8 under air atmosphere. Amorphous mackinawite is the initial phase during crystallization and its stability is poor. The thermal behavior of the corrosion is studied in heat rating 10 °C/min between ambient and 1000 °C using TG-DSC. The mass loss is mainly caused by the release of SO2 between 23 and 397 °C. The maximum exothermic intensity occur between 200 and 400 °C. Oxidation of mackiwite/greigite releases abundance of heat, which served as a trigger for spontaneously self-ignited.
Cai, X., Zhao, X., & Yao, H. (2014). Spontaneous combustion tendency of iron sulfide corrosion: Oxidation characterization and thermostability. In Procedia Engineering (Vol. 84, pp. 356–362). Elsevier Ltd. https://doi.org/10.1016/j.proeng.2014.10.444