Modified heat–resistance for protective coatings for nickle–based superalloys

The paper presents a review of heat–resistant coatings manufacture techniques for Ni–base superalloys. Modern techniques such as: Electron Beam Physical Vapor Deposition (EB–PVD), Low–Pressure Plasm Spray and modified (AltPt, Ale) aluminide coatings are described. Experimentally based results show the microstructure of Al–Cr and Al–Si coatings obtained by pack cementation technique. The coatings changes during their high–temperature service are utilized to determine the distribution of selected elements in coatings both before and after high temperature annealing. High hot–corrosion resistance of Si–modified aluminide coatings have been confirmed. Both microstructure and phase composition of the Al–Cr and Al–Si coatings depend on the chemical composition of the powder mixture applied in pack cementation technique. Chromium forms stable compounds with Al in the mixture while Si appears in the coating layers in a form of precipitation particles with elevated content of Mo, W, Ti and Cr. The Al–Si coatings s...