Damage tolerant cooling of high temperature mechanical system component including a coating
An article may include a substrate, a plurality of cooling holes in the substrate, wherein each of the plurality of cooling holes defines substantially the same diameter measured parallel to an outer surface of the substrate, and a coating on the surface of the substrate. In accordance with these examples, the coating covers and substantially blocks a first set of cooling holes from the plurality of cooling holes and leaves a second set of cooling holes from the plurality of cooling holes substantially uncovered. In some examples, an article including a substrate, a plurality of cooling holes in the substrate, and a coating on the substrate. In accordance with these examples, the coating covers and partially occludes each cooling hole of the plurality of cooling holes, and the coating does not extend into any of the plurality of cooling holes.
1. A method comprising:
forming a plurality of cooling holes in a substrate, wherein each cooling hole of the plurality of cooling holes defines a diameter D 1 measured parallel to a surface of the substrate;
applying a material to occlude the plurality of cooling holes while leaving the surface of the substrate substantially uncovered;
forming an oxide-based thermal barrier or oxide-based environmental barrier coating on the surface of the substrate and a surface of the material; and
forming a respective aperture in the oxide-based thermal barrier or oxide-based environmental barrier coating at each of a plurality of respective locations corresponding to respective locations of the plurality of cooling holes such that the oxide-based thermal barrier or oxide-based environmental barrier coating covers and partially occludes each cooling hole of the plurality of cooling holes, wherein each aperture of the plurality of apertures defines a diameter D 2 above the respective cooling hole, wherein the diameter D 2 is measured parallel to the outer surface of the substrate, and wherein D 2 of the respective aperture in the oxide-based thermal barrier or oxide-based environmental barrier coating is smaller than D 1 of the respective cooling hole; and
after forming the respective aperture in the oxide-based thermal barrier or oxide-based environmental barrier coating at each of the plurality of respective locations corresponding to respective locations of the plurality of cooling holes, heating the substrate and the oxide-based thermal barrier or oxide-based environmental barrier coating to remove remaining material from the plurality of cooling holes.
2. The method of claim 1 , wherein applying the material to occlude the plurality of cooling holes while leaving the surface of the substrate substantially uncovered comprises:
applying the material to occlude the plurality of cooling holes, wherein the material at least partially covers the surface of the substrate; and
removing the material from the surface of the substrate to leave the surface of the substrate substantially uncovered.
3. The method of claim 1 , wherein the material comprises a curable polymer.
4. The method of claim 1 , wherein forming the oxide-based thermal barrier or oxide-based environmental barrier coating on the surface comprises plasma spraying the oxide-based thermal barrier or oxide-based environmental barrier coating on the surface of the substrate.
5. The method of claim 1 , wherein forming the respective aperture in the oxide-based thermal barrier or oxide-based environmental barrier coating at each of the plurality of respective locations corresponding to respective locations of the plurality of cooling holes comprises drilling the respective aperture in the oxide-based thermal barrier or oxide-based environmental barrier coating at each of the plurality of respective locations corresponding to respective locations of the plurality of cooling holes.
6. The method of claim 1 , wherein:
the plurality of cooling holes comprises a first plurality of cooling holes;
the method further comprises:
forming a second plurality of cooling holes in the substrate, wherein the second plurality of cooling holes are interleaved with the first plurality of cooling holes;
applying the material to occlude the plurality of cooling holes while leaving the surface of the substrate substantially uncovered comprises applying the material to occlude the first plurality of cooling holes and the second plurality of cooling holes while leaving the surface of the substrate substantially uncovered;
forming the respective aperture in the oxide-based thermal barrier or oxide-based environmental barrier coating at each of the plurality of respective locations corresponding to respective locations of the plurality of cooling holes comprises forming the respective aperture in the oxide-based thermal barrier or oxide-based environmental barrier coating at each of the plurality of respective locations corresponding to respective locations of the first plurality of cooling holes such that the oxide-based thermal barrier or oxide-based environmental barrier coating covers and partially occludes each cooling hole of the first plurality of cooling holes; and
apertures are not formed in the oxide-based thermal barrier or oxide-based environmental barrier coating at locations corresponding to respective locations of the second plurality of cooling holes.