Method for improving the TBC life of a single phase platinum aluminide bond coat by preoxidation heat treatment
AssigneeGeneral Electric Company
InventorIrene Spitsberg
Life of this patent
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Abstract
A thermal barrier coating system having an improved life as a result of a preoxidation treatment applied to a single phase platinum aluminide bond coat. After coating the substrate to form a diffusion platinum aluminum bond coat, the surface finish of the bond coat was grit blasted with an inert grit of preselected size at a preselected pressure to achieve a predetermined surface finish. After the grit blasting, but before application of the ceramic top coat of yttria-stabilized zirconia (YSZ), the coating was preoxidized to form a thin alumina scale by heat treating the diffusion platinum aluminide bond coat at an elevated temperature at a preselected partial pressure of oxygen.
Claims19
A method for coating a gas turbine component with a thermal barrier coating system by a controlled preoxidation heat treatment, comprising the steps of:
- providing a gas turbine component for use at high temperatures;
- applying a thin layer of platinum to at least a portion of the component;
- forming a single phase platinum aluminide by exposing the thin layer of platinum to a source of aluminum for a preselected time;
- then,
- providing the single phase platinum aluminide with a clean, uniform surface free of oxides, contaminants and local gradients of nickel, aluminum and platinum;
- then,
- preoxidizing the single phase platinum aluminide by heating the component in a preselected partial pressure of oxygen, wherein the preoxidation is accomplished by heating the component to a preselected temperature at a preselected rate so as to form a thin layer of pure alumina over the single phase platinum aluminide;
- followed by,
- applying a ceramic top coat over the thin layer of pure alumina.
A method for coating a gas turbine component with a thermal barrier coating system by a controlled preoxidation heat treatment, comprising the steps of:
- providing a gas turbine component for use at high temperatures;
- applying a thin layer of platinum to at least a portion of the component;
- forming a single phase platinum aluminide by exposing the thin layer of platinum to a source of aluminum for a preselected time;
- grit blasting the single phase platinum aluminide using a grit of preselected size at a preselected pressure for a time sufficient to achieve a surface finish of between about 32 Ra and 63 Ra;
- then,
- preoxidizing the single phase platinum aluminide by heating the component in a vacuum furnace at a preselected partial pressure of oxygen, wherein the preoxidation is accomplished by heating the component to a preselected temperature at a preselected rate so as to form a thin layer of pure alumina over the single phase platinum aluminide;
- followed by,
- applying a ceramic top coat over the thin layer of pure alumina.
Dependencies are inferred from the claim text.