Sulfidation

A chemical reaction of a metal or an alloy with some form of sulfur present in the surrounding environment. Sulfidation attack is a form of accelerated oxidation that can result in rapid degradation of the substrate material due to a loss of corrosion protection. No gas turbine engine is free from sulfidation, because sulfur is usually present in fuel. This corrosive reaction starts at the turbine blade root, then spreads to shrouds and the blade airfoils. Sulfidation is a critical turbine reliability issue that requires regular inspection of hot section parts.