Aluminide-silicide coatings coated products
AssigneesA & A International, LLC, ROLLS-ROYCE plc
InventorsMehar C. Meelu, Alan T. Jones, Bruce G. McMordie
Life of this patent
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Abstract
An improved aluminide coating especially for heat resistant superalloy substrates. Slurry coating compositions of eutectic metal alloy powders and of non-eutectic metal powders. A process for coating the substrates and the coated metal parts. The coatings have improved resistance to developing cracks and to hot corrosion and oxidation.
Claims61
An aluminide-silicide coating on a heat-resistant superalloy substrate, the coating having a highly dispersed distribution of silicide phases throughout the coating's thickness, the coating having resistance to developing cracks and resistance to oxidation and hot corrosion conditions, the coating comprising a layer which comprises a continum of silicide and aluminide phases and a predominantly aluminide layer below and adjacent said layer, the coating being formed from a slurry comprising aluminum, silicon and a powder of a silicide-forming metal in an amount effective to promote the formation and dispersion in the coating of silicides corresponding to the metal.
The superalloy turbine part coated with an aluminide-silicide coating which coating has highly dispersed silicide phases throughout the coating's thickness and which coating comprises a layering layer having substantially continuous interleaved layers of aluminide and silicide phases, and sandwiched between the layering layer and a diffusion interface of the coating with the substrate, a predominately aluminide layer having pronounced silicide precipitates, which coating is formed from a slurry comprising aluminum, silicon, and a powder of a silicide-forming metal in an amount effective to promote the formation and dispersion in the coating of silicides corresponding to the metal.
A diffusion heat treated aluminide-silicide coating structure for a heat resistant alloy substrate containing major proportions of at least one of Ni or Co, the coating having a plurality of zones in depthwise series, including
- a silicon-rich surface zone,
- a pronounced layering zone comprising interleaved layers of aluminide and silicide phases, and
- a predominantly aluminide zone with pronounced silicide precipitates, located between the layering zone and a diffusion interface of the coating with the substrate,
- wherein the surface zone is at least 2 microns thick and the layering zone is at least four times the thickness of the surface zone, subject to a minimum thickness for the layering zone of 12 microns, the coating being formed from a slurry comprising aluminum and silicon, and a powder of a silicide-forming metal in an amount effective to promote the formation and dispersion in the coating of silicides corresponding to the metal.
A diffusion heat treated aluminide-silicide coating structure for a heat resistant alloy substrate containing major proportions of at least one of Ni and Co, the coating having a plurality of zones in depthwise series, including
- a surface zone having a maximum silicon content of less than 25 wt. %,
- a layering zone comprising alternate layers of aluminide and silicide phases, and
- a predominantly aluminide zone with pronounced silicide precipitates, located between the layering zone and a diffusion interface of the coating with the substrate,
- wherein the aluminum content in the layering zone and the aluminide zone is consistently more than 15 wt. % and not more than 30 wt. %.
A diffusion heat treated aluminide-silicide coating structure for a heat resistant alloy substrate containing major proportions of at least one of Ni and Co, the coating having a plurality of zones in depthwise series, including
- a surface zone having a maximum silicon content of less than 25 wt. %,
- a layering zone comprising alternate layers of aluminide and silicide phases, and
- a predominantly aluminide zone with pronounced silicide precipitates, located between the layering zone and a diffusion interface of the coating with the substrate,
- wherein in the layering aluminide zones the aluminum content is not more than 30 wt. % and the aluminum and silicon contents vary therein depthwise in approximately inverse proportion to each other.
A diffusion heat treated aluminide-silicide coating structure for a heat resistant alloy substrate containing major proportions of at least one of Ni and Co, and minor proportions of at least one of Ta and Ti, the coating having a plurality of zones in depthwise series, including
- a surface zone having a maximum silicon content of less than 25 wt. %,
- a layering zone comprising alternate layers of aluminide and silicide phases, and
- a predominantly aluminide zone with pronounced silicide precipitates, located between the layering zone and a diffusion interface of the coating with the substrate,
- wherein the surface zone includes at least one of Ta and Ti in amounts greater than the weight percentage content of the substrate material.
A superalloy turbine part having improved resistance to oxidation and to hot corrosion, which part is coated with an aluminide-silicide coating which coating has highly dispersed silicide phases throughout the coating's thickness and which coating comprises an outer layer which comprises silicon-rich and aluminum-rich phases and a predominantly aluminide layer below and adjacent said outer layer which contains pronounced silicide precipitates, the coating being formed from a slurry comprising aluminide and silicon, and a powder of a silicide-forming metal in an amount effective to promote the formation and dispersion in the coating of silicides corresponding to the metal.
A diffusion heat treated aluminide-silicide coating structure for a heat resistant alloy substrate containing major proportions of at least one of Ni and Co, the coating having a plurality of zones in depthwise series, including
- a surface zone having a maximum silicon content of less than 25 wt %,
- a layering zone comprising alternate layers of aluminide and silicide phases, and
- a predominantly aluminide zone with pronounced silicide precipitates, located between the layering zone and a diffusion interface of the coating with the substrate,
- wherein the surface zone includes at least one of Ta and Ti in amounts greater than the weight percentage content of the substrate material.
A superalloy part coated with an aluminide-silicide coating having a highly dispersed distribution of silicide phases throughout the coating, the coating comprising a layer which comprises a continuum of silicide and aluminide phases and a predominantly aluminide layer below and adjacent said layer, the coating being formed from a slurry comprising aluminum and silicon, and a powder of a silicide-forming metal in an amount effective to promote the formation and dispersion in the coating of silicides corresponding to the metal.
Dependencies are inferred from the claim text.