Internal aluminide coating for vanes and blades and method of manufacture
A gas turbine engine component includes a substrate having first surface and a second surface disposed opposite the first surface, a plurality of holes extending through the substrate from the first surface to the second surface, the holes defined by a plurality of respective walls each extending from the first surface to the second surface, a metallic bond coat disposed on the first surface, and an aluminide coating disposed on the first surface, the second surface, and the walls. The metallic bond coat is disposed between the first surface and the aluminide coating and the walls are free of the metallic bond coat.
1. A method of coating a component of a gas turbine engine, the method comprising:
applying a metallic bond coat to a first surface of a substrate;
drilling a plurality of holes through the metallic bond coat and the substrate, wherein the plurality of holes open to the first surface and an oppositely disposed second surface of the substrate, the holes defined by a plurality of respective walls each extending from the first surface to the second surface; and
applying an aluminide coating to the first surface of the substrate, the walls of the holes, and the second surface of the substrate.
2. The method of claim 1 , wherein the plurality of holes are drilled using electrical discharge machining (EDM).
3. The method of claim 1 , and further comprising grinding the first surface of the substrate prior to applying the metallic bond coat.
4. The method of claim 1 , and further comprising shot peening the metallic bond coat before drilling the plurality of holes.
5. The method of claim 4 , and further comprising applying a ceramic coating to the first surface, wherein the aluminide coating is disposed between the metallic bond coat and the ceramic coating.
6. The method of claim 4 , wherein the ceramic coating has a columnar microstructure.
7. The method of claim 1 , wherein the metallic bond coat is MCrAlY coating.
8. The method of claim 1 , wherein the second surface is an internal surface and wherein the aluminide coating on the second surface has a thickness ranging from 12.7 to 38.1 micrometers (0.0005 inches to 0.0015 inches).
9. The method of claim 1 , wherein the first surface is an external surface and wherein the aluminide coating on the first surface has a thickness ranging from 25.4 to 76.2 micrometers (0.001 inches to 0.003 inches).
10. The method of claim 9 , wherein the component is a rotor blade.
11. The method of claim 1 , wherein a portion of the aluminide coating is diffused into the substrate on the walls of the holes and diffused into the metallic bond coat on the first surface.
12. The method of claim 1 , wherein the first surface is an external surface and the second surface is an internal surface.
13. The method of claim 12 , wherein the component is turbine blade or vane.