Characterization of solid deposits formed from jet fuel degradation under pyrolytic conditions: Metal sulfides

Reaction of the organic sulfur compounds in Jet A with Fe- and Ni-based alloy substrates under pyrolytic conditions formed significant amounts of metal sulfides. Pyrrhotite (Fe_(1-x)S) and heazlewoodite (Ni ₃S₂) were formed on SS316 and Inconel 600 surfaces, respectively, in the short duration experiments. After extended periods of thermal stressing, an additional crystal phase, pentlandite (Fe,Ni) ₉S₈, was also observed on both surfaces. The lack of FeS₂ (pyrite) formation over extended periods of stressing indicates that the amount of sulfur reacting with the substrates decreased with the increasing thermal stressing time. A focused ion beam (FIB)/SEM analysis showed that the metal sulfide formation can extend up to 2 μm depth from the surface in 2 h of thermal stressing. The formation of metal sulfides on alloy surfaces degrades the alloy surfaces and affects solid carbon deposition from jet fuel.