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JP-2026075052-A - Turbine blade outermost polishing layer using gradient ceramic

JP2026075052AJP 2026075052 AJP2026075052 AJP 2026075052AJP-2026075052-A

Abstract

[Problem] To provide a turbine blade comprising an airfoil body having the outermost radial surface relative to the turbine rotor, a bond coat on the outermost radial surface, and an outermost polished layer on the bond coat. [Solution] The blade comprises an airfoil body having the radially outermost surface relative to the turbine rotor, a bond coat on the radially outermost surface, and an outermost polished layer on the bond coat. The outermost polished layer may include a gradient oxide ceramic layer or a gradient metal ceramic layer. In either case, vacuum heat treatment of the outermost polished layer hardens the layer, increasing the friction ratio, improving the clearance between the blade tips, resulting in a smaller tip gap and less leakage compared to conventional systems. The heat-treated polished layer is also resistant to oxidation at high temperatures, such as over 1090°C (approximately 2000°F), caused by the increasing use of high-temperature fuels such as hydrogen. Vacuum heat treatment also results in improved thermal cycling tests. [Selection Diagram] Figure 3

Inventors

  • カラ、エクラヴィア
  • サフー、リトゥプルナ
  • コンター、マキシム
  • パブラ、スリンダー シン
  • セバスチャン マナバラン、アントニー エム．
  • ラジ、ラグル

Assignees

  • ジーイー・ベルノバ・テクノロジー・ゲーエムベーハー

Dates

Publication Date
20260507
Application Date
20250922
Priority Date
20241021

Claims (15)

  1. A turbine blade (114), A blade-shaped section body (124) having the outermost radial surface (160) relative to the turbine rotor (108), The bond coat (172) on the radially outermost surface (160), The outermost polished layer (170) on the bond coat (172), wherein the outermost polished layer (170) is A first layer (180A, 182A) on the bond coat (172) comprising 100% by weight of a first ceramic and 0% by weight of a second ceramic different from the first ceramic, wherein the first ceramic comprises a first layer (180A, 182A) consisting of 8% by weight of yttria-stabilized zirconia (8YSZ), A second layer (180B, 182B) on the first layer (180A, 182A) comprising 65-85% by weight of the first ceramic and 15-35% by weight of the second ceramic, A third layer (180C, 182C) on the second layer (180B, 182B) comprising 40-60 wt% of the first ceramic and 40-60 wt% of the second ceramic, A fourth layer (180D, 182D) on the third layer (180C, 182C) comprising 5 to 25% by weight of the first ceramic and 75 to 95% by weight of the second ceramic, A turbine blade (114) comprising a fifth layer (180E, 182E) on a fourth layer (180D, 182D) containing 0 wt% of the first ceramic and 100 wt% of the second ceramic, and an outermost polished layer (170) containing a gradient oxide ceramic layer (174).
  2. The turbine blade (114) according to claim 1, wherein the bond coat (172) comprises at least one of cobalt-nickel-chromium-aluminum-yttrium (CoNiCrAlY), nickel-chromium-aluminum-yttrium (NiCrAlY), nickel-cobalt-chromium-aluminum-yttrium (NiCoCrAlY), and cobalt-chromium-aluminum-yttrium (CoCrAlY).
  3. The turbine blade ( 114) according to claim 1, wherein the second ceramic comprises one of pure alumina ( Al₂O₃ ) or zirconia-reinforced alumina (ZTA).
  4. The turbine blade (114) according to claim 1, wherein the bond coat (172) has a thickness of 85 to 125 micrometers (μm) (T1, T4), each of the first to fourth layers (180A, 180B, 180C, 180D, 182A, 182B, 182C, 182D) has a thickness of 55 to 75 μm (T2, T5), and the fifth layer (180E, 182E) has a thickness of 100 to 125 μm (T3, T6).
  5. The turbine blade (114) according to claim 1, wherein the outermost polished layer (170) is formed using thermal plasma spraying and post-formation vacuum heat treatment, which includes exposing the gradient oxide ceramic layer (174) to a temperature exceeding 1000°C for a period of at least one hour, and then cooling the gradient oxide ceramic layer (174).
  6. A method for forming an outermost polished layer (170) for the radial outermost surface (160) of a turbine blade (114), Forming a bond coat (172) on the radially outermost surface (160) of the turbine blade (114), To form one of a gradient oxide ceramic layer (174) and a gradient metal ceramic layer (176) on the bond coat (172) on the radially outermost surface (160) of the turbine blade (114), A method comprising heat-treating one of the gradient oxide ceramic layer (174) and the gradient metal ceramic layer (176) on the radial outermost surface (160) of the turbine blade (114).
  7. The method according to claim 6, wherein the heat treatment includes a vacuum heat treatment comprising exposing the outermost polished layer (170) to a temperature exceeding 1000°C for a period of at least one hour, and then cooling the outermost polished layer (170).
  8. The method according to claim 7, wherein the vacuum heat treatment includes raising the temperature of the outermost polished layer (170) to a temperature exceeding 1200°C for a period of at least 1.5 hours, and then cooling the outermost polished layer (170).
  9. The method according to claim 6, wherein the heat treatment includes exposing the outermost polished layer (170) to a temperature of 750°C to 1000°C in air for a period of 30 minutes to 4 hours.
  10. The method according to claim 6, wherein the bond coat (172) comprises at least one of the following: cobalt-nickel-chromium-aluminum-yttrium (CoNiCrAlY), nickel-chromium-aluminum-yttrium (NiCrAlY), nickel-cobalt-chromium-aluminum-yttrium (NiCoCrAlY), and cobalt-chromium-aluminum-yttrium (CoCrAlY).
  11. The outermost polished layer (170) is A first layer (180A, 182A) on the bond coat (172) comprising 100% by weight of a first ceramic and 0% by weight of a second ceramic different from the first ceramic, wherein the first ceramic comprises a first layer (180A, 182A) consisting of 8% by weight of yttria-stabilized zirconia (8YSZ), A second layer (180B, 182B) on the first layer (180A, 182A) comprising 65-85% by weight of the first ceramic and 15-35% by weight of the second ceramic, A third layer (180C, 182C) on the second layer (180B, 182B) comprising 40-60 wt% of the first ceramic and 40-60 wt% of the second ceramic, A fourth layer (180D, 182D) on the third layer (180C, 182C) comprising 5 to 25% by weight of the first ceramic and 75 to 95% by weight of the second ceramic, The method according to claim 6, comprising a gradient oxide ceramic layer (174) including a fifth layer (180E, 182E) on a fourth layer (180D, 182D) which includes 0 wt% of the first ceramic and 100 wt% of the second ceramic.
  12. The method according to claim 11, wherein the second ceramic comprises one of pure alumina ( Al₂O₃ ) or zirconia - reinforced alumina (ZTA).
  13. The method according to claim 11, wherein the bond coat (172) has a thickness of 85 to 125 micrometers (μm) (T1, T4), each of the first to fourth layers (180A, 180B, 180C, 180D, 182A, 182B, 182C, 182D) has a thickness of 55 to 75 μm (T2, T5), and the fifth layer (180E, 182E) has a thickness of 100 to 125 μm (T3, T6).
  14. The outermost polished layer (170) is A first layer (180A, 182A) on the bond coat (172) is made of a first ceramic consisting of 8 wt% yttria-stabilized zirconia (8YSZ) having a porosity of 5-25%, A second layer (180B, 182B) on top of the first layer (180A, 182A) comprising 65-85% by weight of metal and 15-35% by weight of a second ceramic, A third layer (180C, 182C) on the second layer (180B, 182B) comprising 40-60% by weight of the metal and 40-60% by weight of the second ceramic, The method according to claim 6, comprising a gradient metal-ceramic layer (176) including a fourth layer (180D, 182D) on the third layer (180C, 182C) containing 5 to 25% by weight of the metal and 75 to 95% by weight of the second ceramic, and a fifth layer on the fourth layer (180D, 182D) containing 0% by weight of the metal and 100% by weight of the second ceramic.
  15. The method according to claim 14, wherein the second ceramic, unlike the first ceramic, comprises one of pure alumina ( Al₂O₃ ) or zirconia - reinforced alumina (ZTA).

Description

This disclosure generally relates to coatings. More specifically, this disclosure relates to the outermost polished layer of a turbine blade using ceramics. In a gas turbine, air is pressurized by a compressor and used to burn fuel in a combustor, generating a flow of high-temperature combustion gases. These gases flow downstream through one or more turbines, from which energy can be extracted. In such turbines, rows of turbine blades, spaced circumferentially, extend radially outward from a supporting rotor disk. Each blade typically includes a dovetail that allows for assembly and disassembly of the blade in a corresponding dovetail slot in the rotor disk, as well as an airfoil body extending radially outward from the dovetail. The airfoil body has substantially concave positive pressure sidewalls and substantially convex negative pressure sidewalls, extending axially between the corresponding leading and trailing edges and radially between the root and tip. Within a turbine engine, the shroud is a ring of material surrounding the rotating blades. The shroud is stationary and may be formed of a ceramic matrix composite (CMC) protected with an environmentally resistant coating (EBC) to avoid oxidation and thinning in the presence of high-temperature gas flow. Alternatively, the shroud may include metal components protected with a thermal barrier coating (TBC) to avoid oxidation and thinning in the presence of high-temperature air flow. The performance and efficiency of a turbine can be improved by reducing the space between the radial outermost surface of the rotating turbine blades, i.e., the tip and the stationary shroud, thereby restricting the flow of gas over or around the blade tip, and potentially bypassing the blade. For example, blades can be configured so that their tips fit close to the shroud during engine operation. Therefore, generating and maintaining a small tip clearance is particularly desirable for efficiency purposes. During engine operation, the blade tip may rub against the shroud, thereby increasing the gap, resulting in a loss of efficiency, and potentially damaging or destroying the blade set. To reduce efficiency losses, a polishing layer can be provided on the tip to help form a tight contact tolerance with the shroud. In one example, the polishing layer is formed as a continuous but rough ceramic layer, which is typically very hard. Some current techniques use polishing layers containing cubic zirconia (cZ) and hafnia ( HfO₂ ). Other current techniques use a polishing layer containing cubic boron nitride (cBN) in a laser-clad soft nickel borosilicon (NiBSi) matrix on the radially outermost surface of the blade. Hard ceramic materials provide a cutter blade effect from the radially outermost surface of the airfoil blade to the shroud. The use of the above ceramic materials has several drawbacks. For example, the ceramic forming process, such as for cBN and NiBSi matrices, has variables that affect quality, which are difficult to control. Another drawback of the listed ceramic materials, particularly cBN materials, is that, with the increasing use of higher-temperature fuels such as hydrogen, they tend to oxidize at temperatures exceeding the current operating temperatures of turbine engines, for example, 1090°C (approximately 2000°F). Oxidation reduces the hardness of the ceramic and its ability to cut into the shroud and form a seal. Oxidation can also occur during manufacturing, and the rub-in process must be carried out quickly during commissioning to avoid damage to the polished layer. All aspects, examples, and features described below can be combined in any technically possible way. One aspect of the present disclosure is a turbine blade comprising an airfoil body having a radially outermost surface with respect to a turbine rotor, a bond coat on the radially outermost surface, and an outermost polished layer on the bond coat, the outermost polished layer comprising a first layer on the bond coat comprising 100% by weight of a first ceramic and 0% by weight of a second ceramic different from the first ceramic, the first ceramic comprising a first layer consisting of 8% by weight of yttria-stabilized zirconia (8YSZ), and 65-85% by weight of the first ceramic and 15-35% by weight The present invention provides a turbine blade comprising an outermost polished layer containing a graded oxide ceramic layer, which includes a second layer on a first layer containing a second ceramic by weight of %; a third layer on the second layer containing 40-60 wt% of the first ceramic and 40-60 wt% of the second ceramic; a fourth layer on the third layer containing 5-25 wt% of the first ceramic and 75-95 wt% of the second ceramic; and a fifth layer on the fourth layer containing 0 wt% of the first ceramic and 100 wt% of the second ceramic. Another aspect of this disclosure includes any of the aforementioned aspects, wherein the bond coat comprises at least one of the following: cobalt-nickel-