Hot gas path component having near wall cooling features
A method for providing micro-channels in a hot gas path component includes forming a first micro-channel in an exterior surface of a substrate of the hot gas path component. A second micro-channel is formed in the exterior surface of the hot gas path component such that it is separated from the first micro-channel by a surface gap having a first width. The method also includes disposing a braze sheet onto the exterior surface of the hot gas path component such that the braze sheet covers at least of portion of the first and second micro-channels, and heating the braze sheet to bond it to at least a portion of the exterior surface of the hot gas path component.
1. A method of providing micro-channels in a hot gas path component, the hot gas path component including a substrate having an exterior surface, said method comprising:
forming a first micro-channel in the exterior surface of the hot gas path component, the first micro-channel having a first channel width;
forming a second micro-channel in the exterior surface of the hot gas path component such that the second micro-channel is separated from the first micro-channel by a surface gap having a first width;
disposing a braze sheet comprising a first surface and an opposite second surface onto the exterior surface of the hot gas path component such that the braze sheet covers at least a portion of the first and second micro-channels, wherein the braze sheet is formed from a combined powder mixture of a high melting alloy powder and a low melting alloy powder, wherein a proportion of said low melting alloy powder varies between said first surface and said second surface; and
heating the braze sheet to bond the braze sheet to at least a portion of the exterior surface of the hot gas path component.
2. The method in accordance with claim 1 , wherein the first and second micro-channels have a substantially equal second width, and wherein the first width of the surface gap is equal to or greater than the second width of the first and second micro-channels.
3. The method in accordance with claim 1 , wherein heating the braze sheet to bond the braze sheet to at least a portion of the exterior surface comprises heating the braze sheet to bond the braze sheet to the surface gap.
4. The method in accordance with claim 1 , wherein a portion of the braze sheet suspended over each of the first and second micro-channels is subject to deformation at an operating temperature of the hot gas path component, and wherein forming the first and second micro-channels in the exterior surface comprises forming each of the first and second micro-channels with a second width configured to prevent the suspended portion of the braze sheet from drooping into the first and second micro-channels at the operating temperature of the hot gas path component.
5. The method in accordance with claim 1 , wherein disposing the braze sheet onto the exterior surface comprises disposing the braze sheet onto the exterior surface, wherein the braze sheet is fabricated by combining a low melting alloy powder and a high melting alloy powder to form a combined powder mixture.
6. The method in accordance with claim 5 , wherein the low melting alloy powder and the high melting alloy powder are mixed together at a weight ratio in the range between approximately 5:95 to approximately 95:5.
7. The method in accordance with claim 5 , wherein said low melting point powder is present at a lower proportion than said high melting point powder near said first surface.
8. The method in accordance with claim 1 , wherein forming the first and second micro-channels in the exterior surface comprises forming the first and second micro-channels with a second width in the range between approximately 0.040 in. (1.0 mm) and approximately 0.080 in. (2.0 mm).
9. The method in accordance with claim 1 , further comprising forming a recess in the substrate, wherein the first and second micro-channels are formed in the recess.
10. The method in accordance with claim 9 , wherein disposing the braze sheet onto the exterior surface of the hot gas path component comprises disposing the braze sheet within the recess such that the braze sheet covers at least of portion of the first and second micro-channels.
11. A hot gas path component comprising:
a substrate comprising a recess surface;
a first micro-channel formed in said recess surface;
a second micro-channel formed in said recess surface, said second micro-channel separated from said first micro-channel by a surface gap having a first width; and
a braze sheet comprising a first surface and an opposite second surface, said first surface bonded to at least a portion of said recess surface and covering at least a portion of said first and second micro-channels, said braze sheet formed from a combined powder mixture of a high melting alloy powder and a low melting alloy powder, wherein a proportion of said low melting alloy powder varies between said first surface and said second surface.
12. The hot gas path component in accordance with claim 11 , wherein said first and second micro-channels have a substantially equal second width, and wherein said first width of said surface gap is equal to or greater than said second width of said first and second micro-channels.
13. The hot gas path component in accordance with claim 11 , wherein said braze sheet is bonded to said surface gap.
14. The hot gas path component in accordance with claim 11 , wherein a portion of said braze sheet suspended over each of said first and second micro-channels is subject to deformation at an operating temperature of said hot gas path component, and wherein each of said first and second micro-channels comprise a second width configured to prevent said suspended portion of said braze sheet from drooping into said first and second micro-channels at the operating temperature of said hot gas path component.
15. The hot gas path component in accordance with claim 11 , wherein said low melting point powder is present at a higher proportion than said high melting point powder near said second surface.
16. The hot gas path component in accordance with claim 15 , wherein said low melting alloy powder and said high melting alloy powder are mixed together at an average weight ratio in the range between approximately 5:95 to approximately 95:5.
17. The hot gas path component in accordance with claim 11 , wherein said low melting point powder is present at a lower proportion than said high melting point powder near said first surface.
18. The hot gas path component in accordance with claim 11 , wherein said first and second micro-channels comprises a second width in the range between approximately 0.040 in. (1.0 mm) and approximately 0.080 in. (2.0 mm).
19. The hot gas path component in accordance with claim 11 , wherein said substrate comprises a recess formed in an outer surface of said substrate, said recess comprising said recess surface, and wherein said first and second micro-channels are formed within said recess.
20. The hot gas path component in accordance with claim 19 , wherein said braze sheet is disposed within said recess and bonded to at least a portion of said recess surface and covering at least a portion of said first and second micro-channels.