Deposition: Hot Corrosion in Gas Turbine Engines

Abstract

The superalloys employed in industrial marine and aircraft gas turbine engines are among the strongest and most oxidation resistant structural materials known. Moreover, it is common practice to further increase the surface stability of hot turbine components by the use of protective coatings. Nevertheless accelerated oxidation and corrosion occurs and can limit the use life of gas turbine components. The principal constituents of the deposits that accumulate on turbine components that are associated with accelerated corrosion are alkali salts. The source of the alkali constituents are generally believed to be sea salt crystals, which can travel hundreds of miles with the prevailing winds, or salt water contamination of otherwise clean fuels. The objective of the studies reported herein is to relate the modes of deposition of salts with corrosion and investigate the role of char as it affects corrosion so that the appropriate steps can be taken to increase gas turbine life.