Durable thermal barrier coating having low thermal conductivity
View Patent ↗This invention provides a thermal barrier ceramic coating for application to a metallic article, with the ceramic coating having a formula of Nd x Zr 1-x O y with Z dissolved in, where 0<x<0.5 and 1.75<y<2 and wherein Z is an oxide of a metal selected from the group consisting of Y, Mg, Ca, Hf and mixtures thereof. In one embodiment Nd is added at a level up to 7 mole %. In another embodiment Z is yttrium and is added at a level of at least 6 wt %.
1. A metallic article comprising a metallic substrate and a thermal barrier ceramic coating on its surface with the ceramic coating consisting essentially of a formula of Nd x Zr 1-x O y with yttria and hafnia added and dissolved in, where 0<x<0.5 and 1.75<y<2 with up to 7 moles % of Nd 2 O 3 in the ceramic coating.
2. Article of claim 1 wherein with at least 6 wt % of yttria is added and dissolved in.
3. Article of claim 2 with 0.5 to 6 wt % hafnia is added and dissolved in.
4. Article of claim 2 with from 2 to 7 mole % of Nd 2 O 3 and 6 to 10 wt % of yttria dissolved in.
5. Article of claim 4 with 1.5 to 4 wt % of hafnia is added and dissolved in.
6. Article of claim 5 with 7 mole % Nd 2 O 3 and 5 mole % Y 2 O 3 dissolved in.
7. Article of claim 5 with 10 mole % of Nd 2 O 3 and 6 wt % Y 2 O 3 added and dissolved in.
8. Article of claim 1 further comprising a metallic bond coat between the ceramic coating and the metallic substrate.
9. Article of claim 8 wherein the metallic bond coat is a MCrAlY, wherein M is selected from Ni and/or Co.
10. Article of claim 8 wherein the metallic bond coat is an intermetallic aluminide.
11. Article of claim 8 wherein the protective ceramic top coat has a thickness of about 5 to 50 μm.
12. Article of claim 1 wherein the ceramic coating has a columnar microstructure.
13. Article of claim 12 wherein the columnar microstructure is a straight or a saw tooth structure.
14. Article of claim 1 wherein the ceramic coating has a layered microstructure with interface boundaries between the layers.
15. Article of claim 1 further comprising a protective ceramic top coat overlaying the ceramic coating.
16. Article of claim 15 wherein the protective ceramic top coat is the ceramic coating with a dense columnar microstructure.
17. Article of claim 15 wherein the protective ceramic top coat is 6 to 8 wt % YSZ.
18. Article of claim 1 wherein the ceramic coating has a thermal conductivity of from about 0.78 to 1.02 W/mK from 600° C. to 1100° C.
19. Article of claim 1 wherein the ceramic coating has been applied by EBPVD, air plasma spray or HVOF.
20. Article of claim 1 wherein the metallic article is a turbine component.
21. Article of claim 20 wherein the turbine component has a metallic substrate of a nickel or cobalt based superalloy.
22. Article of claim 1 wherein the ceramic coating has a thickness within the range of about 5 to 500 μm.
23. A metallic article comprising a metallic substrate and a thermal barrier ceramic coating on its surface, the ceramic coating consisting essentially of a formula of Nd x Zr 1-x O y with yttria and hafnia added and dissolved in wherein 0<x<0.5 and 1.75<y<2, with at least 6 wt % of yttria dissolved in.
24. Article of claim 23 with 0.5 to 6 wt % hafnia is added and dissolved in.
25. Article of claim 23 having 6 to 10 wt % of yttria dissolved in and 2 to 15 mole % Nd 2 O 3 .
26. Article of claim 25 with 1.5 to 4 wt % of hafnia is added and dissolved in.
27. Article of claim 26 with 7 mole % Nd 2 O 3 and 5 mole % Y 2 O 3 dissolved in.
28. Article of claim 26 with 10 mole % of Nd 2 O 3 and 6 wt % Y 2 O 3 added and dissolved in.
29. Article of claim 23 wherein the ceramic has a non-pyrochlore crystal structure.
30. Article of claim 23 further comprising a metallic bond coat between the ceramic coating and the metallic substrate.
31. Article of claim 30 wherein the metallic bond coat is a MCrAlY, wherein M is selected from Ni and/or Co.
32. Article of claim 30 wherein the metallic bond coat is intermetallic aluminide.
33. Article of claim 23 wherein the ceramic coating has a columnar microstructure.
34. Article of claim 33 wherein the columnar microstructure is a straight or a saw tooth structure.
35. Article of claim 23 wherein the ceramic coating has a layered microstructure with interface boundaries between layers.
36. Article of claim 23 further comprising a protective ceramic top coat overlaying the ceramic coating.
37. Article of claim 36 wherein the protective ceramic top coat is the ceramic coating with a dense columnar microstructure.
38. Article of claim 36 wherein the protective ceramic top coat is 6–8 wt % YSZ having a thickness of about 5 to 50 μm.
39. Article of claim 23 wherein the ceramic coating has a thermal conductivity of from about 0.72 to 1.02 W/mK from 600° C. to 1100° C.
40. Article of claim 23 wherein the ceramic coating has been applied by EBPVD, air plasma spray or HVOF.
41. Article of claim 23 wherein the metallic article is a turbine component.
42. Article of claim 41 wherein the turbine component has a metallic substrate of a nickel or cobalt based superalloy.
43. A method for applying a thermal barrier ceramic coating to a metallic article comprising:
forming a ceramic consisting essentially of a formula Nd x Zr 1-x O y with yttria and hafnia added and dissolved in, wherein 0<x<0.5 and 1.75<y<2 with at least 6 wt % of yttria is added and dissolved in, by doping yttria, hafnia and neodymia into a zirconia ceramic; and
applying the ceramic as a coating onto the metallic article.
44. Method of claim 43 wherein the ceramic is applied by electron beam physical vapor deposition.
45. Method of claim 43 with 0.5 to 6 wt % hafnia added and dissolved into a zirconia ceramic.
46. Method of claim 45 wherein 7 mole % of Nd 2 O 3 and 5 mole % Y 2 O 3 are doped into ZrO 2 .
47. Article of claim 45 with 10 mole % of Nd 2 O 3 and 6 wt % Y 2 O 3 added and dissolved in.
48. Article of claim 47 with 1.5 to 4 wt % of hafnia added and dissolved in.