THERMAL FATIGUE RESISTANCE OF PROTECTIVE COATINGS FOR GAS-TURBINE BLADES

Results of the investigation of thermocyclic strength of flat corset-t ype specimens (hour-glass-shape) (Getsov, L. B. et al., Industr. Lab., 1982, 7, 44) from nine heat resistant alloys on a nickel base with p rotective coatings: electron-beam, i.e. single-layer system M-Cr-Al-Y, multilayer, dual-layer, diffusion, slurry and plasma spray coatings a re represented. It is shown that the service life of electron-beam coa tings is considerably higher than that of the pack cementation and slu rry alumosilicide coatings. Dual-layer overlay coatings with an extern al ceramic layer have the optimum characteristics. Regularities are es tablished for microcrack initiation and propagation in coatings and hi gh-temperature alloys, depending upon the technology of the coating's deposition and test conditions.