Protective Coatings for Materials in High Temperature Technology — European R & D Needs —

Abstract

Protective coatings have long been used for materials in service at normal temperatures - paint and electrodeposits of Ni and Cr are familiar to all. The use of coatings on materials operating at elevated temperatures is much more recent, and was largely introduced for the protection of nozzle and rotor blades in aircraft gas turbines when the increasingly severe temperature conditions led to the most advanced creep-resisting alloys being insufficiently resistant to oxidation and sulphidation. A number of efficient coating systems have been developed successfully for this field of application, but they have not yet been widely adopted outside the gas- turbine field in spite of the fact that hot corrosion problems arise in a number of industrial processes, mainly in the field of energy generation, conversion and usage. These generally involve environments different from those for which the established coatings were developed. It is therefore the purpose of this note to consider whether protective coatings are applicable in these other fields of engineering, and to suggest the direction in which further research and development is required to bring this about.