Rolls-royce Corporation

Chromalloy United Kingdom Limited

Rodney G Wing

David S Rickerby

Stanley R Bell

A high rhenium containing single crystal superalloy (30) is chromized, or coated with cobalt, before the conventional aluminising process steps to modify the surface of the high rhenium containing single crystal superalloy to prevent the formation of topologically close packed phases at the interface between the aluminide coating (32) and the rhenium containing single crystal superalloy. The invention is particularly applicable to platinum aluminide coatings, platinum aluminide-silicide coatings and aluminide-silicide coatings.

Method of aluminising a superalloy

A ceramic thermal barrier coating layer for a superalloy article is caused to adhere to the superalloy article by applying platinum to the superalloy article and heat treating at a temperature of 1100.degree. C. to 1200.degree. C. for one hour. This causes aluminum to diffuse from the superalloy article into the platinum to form a platinum enriched outer layer which generally includes a platinum enriched gamma phase and a platinum enriched gamma prime phase. An alumina layer is formed between the platinum enriched outer layer and a ceramic coating. The platinum enriched gamma phase and the platinum enriched gamma prime phase in the outer layer reduces the migration of transition metal elements to the ceramic coating to enable a very pure alumina layer to be formed.

Article including thermal barrier coated superalloy substrate

A multi-layer thermal barrier coating (42) for a superalloy article (40) comprises a platinum enriched superalloy layer (44), an MCrAlY bond coating (46) on the platinum enriched superalloy layer (44), a platinum enriched MCrAlY layer (48) on the MCrAlY bond coating (46), a platinum aluminide coating (50) on the platinum enriched MCrAlY layer (48), an oxide layer (54) on the platinum aluminide coating (50) and a ceramic thermal barrier coating (56) on the oxide layer (54). The platinum aluminide coating (50) and the platinum enriched MCrAlY layer (48) reduce movement of transition metals from the superalloy substrate (40) and the MCrAlY bond coating (46) to the oxide layer (54) so that the oxide layer is very pure alumina. The platinum enriched superalloy layer (44) reduces movement of aluminium from the MCrAlY bond coating (46) to the superalloy substrate (40) so that the oxide layer (54) remains pure alumina to improve long term adhesion of the ceramic thermal barrier coating (56), and additionally reduces movement of transition metals from the superalloy substrate (40) to the oxide layer (54).

Thermal barrier coating for a superalloy article and a method of

Method of applying a thermal barrier coating to a superalloy article and

A circumferential array of aerofoil blades (11) comprising an aerofoil portion and a root portion is mounted on the periphery of a disc (14), sealed in place under vacuum and subsequently hot isostatically pressed to achieve diffusion bonding across the interface between the array (11) and the disc (14). Each of the root portion of the array (11) and the disc (14) is provided with axially extending flanges (12, 13, 15 and 16) at its axial ends. The flanges (12, 13, 15 and 16) are so dimensioned that when the array (11) is mounted on the disc (14) the flanges (12, 13, 15 and 16) engage each other in close fitting relationships in such a way that the array (11) and the disc (14) have an enclosed annular chamber radially spacing them apart. Annular chambers (18, 19) are provided at the interfaces of the confronting flanges (12, 13, 15 and 16), and the regions of the interfaces between the chambers (18) and the free axial ends of the flanges (12, 13, 15 and 16) are sealed by vacuum brazing. The outermost chambers (18) prevent the braze material from penetrating the interface between the array (11) and the disc (14), and from penetrating the second annular chambers (19). During hot isostatic pressing an enclosed annular chamber (20) collapses and diffusion bonding occurs between the array (11) and the disc (14) as well as between the flanges (12, 13, 15 and 16). The second annular chambers (19) are designed to collapse to provide a visual indication of the success of the pressing step.

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Nottingham, United Kingdom

Rodney G Wing