Behaviour of NiAl air plasma sprayed coatings in chlorine-containing atmospheres

Chlorine-containing atmospheres are encountered in several industrial processes, leading to severe corrosion phenomena. The application of thermally sprayed protective coatings is one of the solutions to improve the resistance of steels to chlorine corrosion at high temperature and to promote their long-term resistance. Thermodynamic calculations allow the establishment of the stability areas of metals as well as their corresponding oxides and chlorides as a function of the chlorine and oxygen partial pressures of the atmosphere. The coefficient of thermal expansion of a cylindrical bulk NiAl specimen was measured using a L75/1550 dilatometer from Linseis. The diffusion experiments were carried out in a tube furnace made of alumina under argon.