Coatings are mandatory to protect hot components in turboengines and e
nergy producing systems. The materials or alloys of these components a
re, indeed, subjected to a number of attacks which include oxidation,
sulphidation, carburisation, chlorination, fluorination, hot corrosion
by molten salt deposits and erosion/corrosion. Since 40 years a consi
derable number of coatings have been perfected to answer this problem.
In this paper the wealth of available coatings and coating deposition
processes are reviewed and a classification is proposed to shed some
light in this maze of coatings.