Service life of heat-resistant alloys with protective coatings in thermocyclic loading

A method to determine the resistance to thermocyclic loading of protective coatings is presented. Examples are given of how to use it to determine elements of the coating and the base metal structure where initial cracks are being formed at thermocyclic loading with given parameters — outer or inner regions of one-layer coatings, peeling-off of the coatings. The efficiency of plastic interlayers, which retard the formation of cracks out of the coating into the base metal for multi-layer electron-beam coatings, is established. The influence of chemical composition of the coating and the base metal, finish thermal treatment and long-duration isothermal holdings on the resistance of the coatings to thermal fatigue is shown.