Articles for high temperature service
Articles coated via a plasma spray process, and methods for making such articles, are presented. For example, one embodiment is an article comprising a substrate comprising a top surface and a channel disposed in the substrate. The channel is defined by an internal channel surface disposed beneath the top surface and having a terminal end at an orifice at the top surface. A coating is disposed on the top surface and on at least a portion of the internal channel surface. A coating thickness at any point on the internal channel surface is less than a nominal coating thickness on the top surface, and the coating comprises a plurality of at least partially melted and solidified particles.
1. An article comprising:
a substrate comprising a top surface and a channel disposed in the substrate, the channel defined by an internal channel surface disposed beneath the top surface and having a terminal end at an orifice at the top surface; and
a coating disposed on the top surface and on at least a portion of the internal channel surface, wherein a coating thickness at any point on the internal channel surface is less than a nominal coating thickness on the top surface, and wherein the coating comprises a plurality of at least partially melted and solidified particles,
wherein the coating comprises a matrix comprising a substantially equiaxed grain morphology; and a plurality of vertically oriented cracks disposed in the matrix, and wherein the coating comprises a ceramic material or a metal material.
2. The article of claim 1 , wherein the channel is disposed at a non-zero angle relative to a normal to the top surface.
3. The article of claim 2 , wherein the coating disposed on a portion of the internal channel extending from the top surface to a throat threshold has a tapered thickness.
4. The article of claim 2 , wherein a thickness of the coating disposed at a throat threshold is less than about 10% of a channel diameter.
5. The article of claim 1 , wherein the orifice has a diameter of up to about 2.5 millimeters.
6. The article of claim 1 , wherein the orifice has a diameter of up to about 1.25 millimeters.
7. The article of claim 1 , wherein the ceramic material comprises material selected from the group consisting of stabilized zirconia, zirconates, and stabilized oxides.
8. The article of claim 1 , wherein the metal material comprises aluminum, nickel, MCrAlY, or an aluminide material.
9. The article of claim 1 , wherein the coating comprises a composite material, the composite comprising the metal and the ceramic.
10. The article of claim 1 , wherein the nominal coating thickness on the top surface is up to about 0.8 millimeters.
11. The article of claim 1 , further comprising an internal cooling system comprising the channel, wherein the channel defines a flow path for a fluid.
12. The article of claim 11 , wherein the coating disposed on the internal channel surface has a thickness such that an air flow through the channel out of the orifice is at least about 80% of an air flow through an uncoated channel of substantially identical channel dimensions for similar air flow conditions.
13. The article of claim 1 , wherein the top surface comprises a plurality of the channels.
14. The article of claim 1 , wherein the article is a component of a gas turbine assembly.
15. The article of claim 14 , wherein the article is a rotating airfoil, a stationary airfoil, a shroud, a combustion liner, or a combustor splash plate.
16. The article of claim 1 , wherein the coating disposed on the internal channel surface is in an as-produced condition.
17. A component for a turbine assembly, comprising:
a substrate comprising a top surface and an internal cooling system, the cooling system comprising a plurality of channels disposed in the substrate at a non-zero angle relative to a normal to the top surface, each channel defined by an internal channel surface disposed beneath the top surface and having a terminal end at an orifice at the top surface; and
a coating disposed on the top surface and on at least a portion of the internal channel surfaces, wherein a coating thickness at any point on the internal channel surfaces is less than a nominal coating thickness on the top surface, and wherein the coating comprises a plurality of at least partially melted and solidified particles,
and wherein the coating comprises a matrix comprising a substantially equiaxed grain morphology; and a plurality of vertically oriented cracks disposed in the matrix.
18. The component of claim 17 , wherein the coating comprises a ceramic material or a metal material.
19. The component of claim 17 , wherein the coating comprises a ceramic material selected from the group consisting of stabilized zirconia, zirconates, and stabilized oxides.
20. The component of claim 17 , wherein the coating comprises a metal material comprising aluminum, nickel, MCrAlY, or an aluminide material.