| Abstract: | | 1. |
With thermal cycling loading for coated specimens microracks occur in brittle coating layers, and conditions for their formation depend not only on coating composition, but also on the composition of the metal being protected, and operating conditions (time, temperature).
| | 2. |
Propagation of thermal fatigue microcracks into the basic metal is determined not only by the difference in linear thermal expansion coefficients, elasticity moduli of the coating and basic metal, but it also depends on the thickness of the coating, cycle parameters, aggressivity of the corrosive medium, relative position of the cracks formed, and the level of heterogenetiv for the coating itself.
| | 3. |
In order to provide reliable protection for turbine blades from corrosion, coating selection should be carried out with reference to actual operating conditions and the grade taking account of chemical composition) of the basic material.
| | 4. |
Numerical evaluation of the features of surface microcrack growth from coatings into the basic metal with thermal cycling loading should be carried out on the basis of threshold aggressivity of the corrosive medium.
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I. I. Polzynov Central Institute of Boiler Turbines, Leningrad. Translated from Problemy Prochnosti, No. 12, pp. 30–35, December, 1988. |
