Thermal barrier coating system for superalloy components

DETAILED DESCRIPTION OF THE DRAWINGS FIG.
1 is a schematic cross-sectional line drawing showing a coating in accordance with my present invention, wherein the aluminide coating 5 is applied to the superalloy substrate 6 and an adherent alumina scale layer 7 is formed on the aluminide coating 5.
The columnar grain ceramic layer 8 overlays the alumina layer 7.
FIG.
2 is a photomicrograph of a zirconia insulative layer deposited on superalloy substrate in accordance with my present invention.
In this thermal barrier coating system, a diffusion aluminide oxidation resistant layer 10 was deposited directly on the Mar-M247 superalloy substrate 12 and a yttria-stabilized zirconia thermal barrier coating 14 was applied to the substrate.
As may be seen from FIG.
2, a thin alumina film 16 is formed between the diffusion aluminide coating and the zirconia coating.
The Hf content of the superalloy substrate enhances the adhesion of the alumina layer formed on the aluminide and to which the zirconia layer is adherred.
FIG.
3 is a photograph of a turbo-prop engine turbine showing high pressure turbine blades mounted in disc 20.
Blades 22 and 24 shown as whitish, have been coated in accordance with my present invention with yttria-stabilized zirconia.
The blades are shown subsequent to 240 hours service in a TPE 331-10 Turbo-prop Engine.
EXAMPLE 1 TPE 331-10 turboprop engine high pressure turbine blades of IN-100 alloy were coated with a diffusion aluminide plus EB-PVD yttria-stabilized zirconia system.
The commercially available Chromalloy RT-21 pack cementation diffusion nickel aluminide coating was applied to a nominal thickness of 2 mils.
Following application of the diffusion aluminide coating layer, the yttria (approximately 20%) stabilized zirconia coating layer was applied to the surface of the aluminide coated blades, by the commercial Airco Temescal EB-PVD process.
The thickness of the zirconia coating was also 2 mils.
The ceramic coating was applied by evaporating a yttria-stabilized zirconia ingot with power provided by a high-energy electron beam gun focused magnetically onto the zirconia target, which was the vapor source