WO2014143244A1

WO2014143244A1 - Coating system for improved erosion protection of the leading edge of an airfoil

Info

Publication number: WO2014143244A1
Application number: PCT/US2013/073575
Authority: WO
Inventors: Sungbo SHIM, Jr.; Raymond Sinatra
Original assignee: Cybulsky, Michael
Priority date: 2013-03-13
Filing date: 2013-12-06
Publication date: 2014-09-18
Also published as: US20140272166A1

Abstract

A gas turbine engine includes airfoils. At least a portion of the airfoils are coated with a coating that provides for erosion and corrosion protection for the portion of the airfoils.

Description

COATING SYSTEM FOR IMPROVED EROSION PROTECTION OF THE LEADING EDGE OF AN AIRFOIL

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application Number 61 /779,722, filed 13 March 2013, the disclosure of which is now incorporated herein by reference.

Field of the Disclosure:

[0002] The present disclosure relates generally to coatings, and more specifically to coating systems to reduce erosion and corrosion in gas turbine engines.

BACKGROUND

[0003] Gas turbine engines are used to power aircraft, watercraft, power generators, and the like. Gas turbine engines typically include a compressor, a combustor, and a turbine. The compressors and turbine of the turbine engine can include turbine disks or turbine shafts, as well as a number of blades mounted to the turbine disks/shafts that extend radially outwardly therefrom into the gas flow path. Also included in the turbine engine are rotating, as well as static, seal elements that channel the airflow used for cooling certain components such as turbine blades and vanes. The airflow channeled by these rotating, as well as static, seal elements carry corrodant deposits to the turbine blades. As the maximum operating temperature of the turbine engine increases, the turbine blades are subjected to higher

temperatures. Debris entering the engine can present issues for the compressor and other components.

[0004] Alkaline sulfate, sulfites, chlorides, carbonates, oxides, and other corrodant salt deposits can be sources of erosion and corrosion. In addition, ingested dirt, fly ash, volcanic ash, concrete dust, sand, sea salt, etc. are a major source of erosion. This can lead to failure or premature removal and replacement of the compressor blades unless the damage is reduced or repaired. Conventional plasma vapor deposition (PVD) processes such as cathodic arc and E-beam PVD are widely used methods for depositing erosion resistant coatings on the airfoils of compressor blades and vanes. However, PVD processes such as cathodic arc and E-beam PVD typically introduce high residual stress on the leading edge of the compressor airfoils during the coating process. When high residual stress from the coating process is coupled with out-of-plane stress from the leading edge geometry and thermal expansion mismatch between coating and substrate, it can result in coating spallation in the as-coated condition providing insufficient leading edge erosion protection.

[0005] Coating methods and coating compositions for compressor blades and vanes that provide high angle solid particle erosion protection on the leading edge of compressor airfoils are desired. Coating methods and coating compositions that also provide lower angle solid particle erosion protection on the concave and convex sides of the airfoils are desired.

SUMMARY

[0006] The present application discloses one or more of the features recited in the appended claims and/or the following features which, alone or in any

combination, may comprise patentable subject matter.

[0007] A coating system in accordance with the present disclosure may include the application of an erosion resistant coating to a portion of a gas turbine engine blade. In some embodiments, the coating may be applied to a preselected exterior surface of the airfoil blades. The coating may be applied to the leading edge surface of the airfoil to increase the erosion resistance of the leading edge. The coating may also be applied to the concave side surface, the convex side surface, or combinations thereof.

[0008] In some embodiments, the coating may be formed from tungsten- tungsten carbide, tungsten carbide cobalt, cobalt-chrome-tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, or a diamond like carbon material. The process may also include a metallic bond coat layer positioned between the coating and the surface of the airfoil. The surface of the airfoil may also be nitrided or carburized before the application of the coating.

[0009] In some embodiments, the coating may be applied to the airfoil using high velocity oxygen fuel spray, high velocity air fuel spray, solution plasma spray, cold spray, chemical vapor deposition, electo spark deposition, plasma enhanced chemical vapor deposition, or air plasma spray method. [0010] In illustrative embodiments, a method for coating a portion of a gas turbine compressor component comprises the steps of providing a gas turbine compressor component, the component further comprising an airfoil section having an exterior surface and applying a coating layer to a preselected exterior surface selected from the group consisting of the leading edge surface, the concave side surface, the convex side, and combinations thereof to minimize weight, minimize fatigue debit, and minimize repair costs.

[0011 ] In some embodiments, the coating layer is selected from the group consisting of TiAIN, ΑΙΤΊΝ, ΤΊΑΙΝ/ΤΊΝ multilayer, TiAIN/Cr multilayer, tungsten- tungsten carbide, tungsten carbide cobalt, cobalt-chrome-tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon.

[0012] In some embodiments, the coating layer at the leading edge surface has a thickness from about 1 0 μπ) to about 1 00 μπ).

[0013] In some embodiments, the coating layer at the leading edge surface has a thickness from about 1 0 μπ) to about 75 μπ).

[0014] In some embodiments, the coating layer at the concave and convex surfaces is from about 5 μπ) to about 50 μπ).

[0015] In some embodiments, the method further includes the step of applying a metallic bond coat layer to the exterior surface of the airfoil before the coating layer.

[0016] In some embodiments, the metallic bond coat layer has a thickness from about 2.5 μπ) to about 1 0 μπ).

[0017] In some embodiments, the metallic bond coat layer is selected from the group consisting of Ni, Ti, and Cr.

[0018] In some embodiments, the process further includes the step of nitriding the surface of the airfoil.

[0019] In some embodiments, the nitrided depth is from about 1 0 μπ) to about 50 μηι.

[0020] In some embodiments, the process further includes the step of carburizing the surface of the airfoil.

[0021 ] In some embodiments, the carburized depth is from about 1 0 μπ) to about 50 μηι. [0022] In some embodiments, the coating is applied using coating spray methods from the group consisting of PVD, HVOF, HVAF, solution plasma spray, air plasma spray, cold spray, CVD, electro spark deposition, and PE-CVD.

[0023] In some embodiments, the coating powder size is less than 50 μ/η.

[0024] In some embodiments, the powder size is less than 20 μηη.

[0025] In some embodiments, the hardness of the coating layer is between about 1 ,200 Hv and about 2,00 Hv.

[0026] In some embodiments, the hardness of the coating layer is between about 1 ,400 Hv and about 1 ,600 Hv.

[0027] In some embodiments, the coating layer adds about 0.1 % to about 7% additional weight to the gas turbine compressor component.

[0028] In some embodiments, the coating layer adds about 0.1 % to about 3% additional weight to the gas turbine compressor component.

[0029] In some embodiments, an outer surface of the coating layer has a surface finish of about 3 μίηοΐπβε to about 25 μίηοΐπβε.

[0030] In some embodiments, the surface finish is about 5 μίηοΐπβε to about 1 5 μίηοΐπβε.

[0031 ] In some embodiments, the gas turbine compressor component is metallic.

[0032] In some embodiments, the gas turbine compressor component is made from one of a stainless steel alloy, a titanium alloy, and a nickel-based alloy.

[0033] In illustrative embodiments, a gas turbine compressor component comprises an airfoil including a leading edge, a concave surface, and a convex surface arranged to face opposite the concave surface, a first coating applied to the leading edge, and a second coating applied to the concave surface.

[0034] In some embodiments, the first coating and the second coating are selected from the group consisting of TiAIN, AITiN, TiAIN/TiN multilayer, TiAIN/Cr multilayer, tungsten-tungsten carbide, tungsten carbide cobalt, cobalt-chrome- tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon.

[0035] In some embodiments, the first coating is different than the second coating. [0036] In some embodiments, the second coating is applied to the convex surface.

[0037] In some embodiments, the gas turbine compressor component further comprises a third coating applied to the convex surface.

[0038] In some embodiments, the first coating, the second coating, and the third coating are selected from the group consisting of TiAIN, AITiN, TiAIN/TiN multilayer, TiAIN/Cr multilayer, tungsten-tungsten carbide, tungsten carbide cobalt, cobalt-chrome-tungsten carbide, chrome carbide-nickel, chrome carbide-nickel- chrome, and diamond like carbon.

[0039] In some embodiments, the first coating is different than the second and third coatings.

[0040] In some embodiments, the second coating is different than the first and third coatings.

[0041 ] In some embodiments, the first coating, the second coating, and the third coating are all different.

[0042] In some embodiments, the first coating has a thickness from about 1 0 μ/η to about 75 μ/η.

[0043] In some embodiments, the coating layer at the concave and convex surfaces is from about 5 μπ) to about 50 μ/η.

[0044] In some embodiments, the second coating is applied to the leading edge to locate the first coating between the second coating and the leading edge of the airfoil.

[0045] In some embodiments, the first coating and the second coating are selected from the group consisting of TiAIN, AITiN, TiAIN/TiN multilayer, TiAIN/Cr multilayer, tungsten-tungsten carbide, tungsten carbide cobalt, cobalt-chrome- tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon.

[0046] In some embodiments, the first coating is different than the second coating.

[0047] These and other features of the present disclosure will become more apparent from the following description of the illustrative embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Fig. 1 is a perspective view of a turbine with portions broken away to show the vanes within the turbine;

[0049] Fig. 2 is a perspective view of a vane segment showing a series of airfoils;

[0050] Fig. 2A is a perspective view of a series of compressor blades with each compressor including an airfoil;

[0051] Fig. 3 is a sectional view taken along lines 3-3 of Fig. 2 showing an airfoil having the coating of the present disclosure formed on the leading edge of the airfoil;

[0052] Fig. 4 is a sectional view of an airfoil having the coating of the present disclosure formed on a surface of the leading edge of the airfoil;

[0053] Fig. 5 is a sectional view of an airfoil having the coating of the present disclosure formed on the leading edge and concave side of the airfoil;

[0054] Fig. 6 is a sectional view of an airfoil having the coating of the present disclosure formed on the leading edge and the concave and convex sides of the airfoil;

[0055] Fig. 7 is a sectional view of an airfoil having the coating of the present disclosure formed on the leading edge on an airfoil that has been nitrided or carburized and treated with a metallic bond coat layer.

[0056] Fig. 8 is a photograph of an airfoil sample showing erosion of the leading edge of the airfoil due to sand ingestion;

[0057] Fig. 9 is a photograph of another airfoil sample showing erosion to the leading edge of the airfoil; and

[0058] Fig. 10 includes photographs of test samples showing erosion of the leading edge of airfoil samples.

DETAILED DESCRIPTION OF THE DRAWINGS

[0059] For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to a number of illustrative embodiments illustrated in the drawings and specific language will be used to describe the same.

[0060] The present disclosure is directed to a coating system that provides an enhanced airfoil 14 including leading edge erosion protection for a turbine 1 1 , as shown in Figs. 1 -2A. More particularly, the present disclosure is directed to one or more coatings that provide enhanced high angle solid particle erosion protection on compressor airfoils 14, as shown, for example, in Figs. 3-7. The coating is primarily applied to the leading edge 12 of the airfoils 14, as shown in Figs. 3, 4, and 7. The coating(s) may also provide low angle solid particle erosion protection on the concave 16 and convex 18 sides of the airfoils 14, as shown in Figs 5 and 6.

[0061] The coating 31 , for example, formed on the leading edge 12 of the airfoils 14 is selected from group consisting of tungsten-tungsten carbide, tungsten carbide cobalt, cobalt-chrome-tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon. The coating 31 on the leading edge 12 is preferably applied by use of a high velocity oxygen fuel (HVOF) spray, a high velocity air fuel (HVAF) spray, a solution plasma spray, a cold spray, chemical vapor deposition (CVD), electro spark deposition, plasma enhanced chemical vapor deposition (PE-CVD), or air plasma spray method. By applying the coating 31 primarily to the leading edge 12, weight increase of the airfoils 14 is minimized. The coating 31 also provides increased corrosion resistance.

[0062] In one illustrative embodiment, airfoil 14 may have first coating 31 applied to leading edge 12 while a second coating 32 is applied to both concave surface 16 and convex surface 18 as shown in Fig. 3. In another illustrative embodiment, airfoil 14 may have first coating 31 applied to leading edge 12 while second coating 132 is applied over first coating and on both concave and convex surfaces 16 and 18 as shown in Fig. 4. In still yet another illustrative example, airfoil 14 may have a coating 231 applied to both leading edge 12 and concave surface 16 while omitting any coating on convex surface 18 as shown in Fig. 5. In another illustrative embodiment, airfoil 14 may have a coating 331 applied to leading edge 12, concave surface 16, and convex surface 18 as shown in Fig. 6. In still yet another illustrative example, airfoil 14 may have a first coating 431 applied to leading edge 12, concave surface 16, and convex surface 18 and a second coating 432 applied over first coating 431 at leading edge 12.

[0063] In still yet another example, airfoil 14 may have a first coating applied to leading edge 12, a second coating applied to concave surface 16, and a third coating applied to convex surface 18. The first, second, and third coatings may be all the same, all different, or any suitable combination thereof. [0064] In addition, the first coating may be applied to leading edge 1 2, concave surface 1 6, and convex surface 1 8. One or more coatings may be applied over the first coating on one or more of the leading edge 1 2, concave surface 16, and convex surface 18. In some examples, the first coating may be the same or different than the one or more coatings.

[0065] The coatings 31 , 32, 1 32, 231 , 331 , 431 , 432 discussed previously are selected from the group consisting of TiAIN, ΑΙΤΊΝ, TiAIN/TiN multilayer, TiAIN/Cr multilayer, tungsten-tungsten carbide, tungsten carbide cobalt, cobalt-chrome- tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon. The coatings 31 , 32, 1 32, 231 , 331 , 431 , 432 may be applied by applied by PVD, HVOF, HVAF, solution plasma spray, cold spray, CVD, electro spark deposition, or PE-CVD.

[0066] Conventional PVD processes such as cathodic arc and E-beam PVD are widely used methods for depositing erosion resistant coatings. However, PVD processes such as cathodic arc and E-beam PVD typically introduce high residual stress on the leading edge of the compressor airfoils during the coating process. When high residual stress from the coating process is coupled with out-of-plane stress from the leading edge geometry and thermal expansion mismatch between coating and substrate, it can result in coating spallation in the as-coated condition and insufficient leading edge erosion protection during engine operation. Coatings applied by HVOF, HVAF, solution plasma spray, cold spray, CVD, electro spark deposition, and PE-CVD can introduce lower residual stresses on the leading edge 1 2 of the compressor airfoil 14 when the right coating materials are used, which leads to better high angle solid particle erosion protection on the leading edge 1 2.

[0067] If coating spray methods such as HVOF, HVAF, solution plasma spray, and cold spray are used, a powder size less than 50 μ/η is used normally to obtain a smooth surface finish. The powder size is preferably smaller than 20 μπ) to obtain the desired finish on the airfoil 14. For both the leading edge coatings 1 2 and the convex 1 8 and the concave 1 6 side coatings, Ni, Ti, Cr, or other metallic bond coat layers 24 can be used between the coatings and the airfoil 14. The surface of the airfoil 14 can be nitrided and carburized 431 before the application of the coating 432 to improve corrosion and erosion resistance, as shown, for example, in Fig. 7. [0068] In one example, the thickness of the coating 31 , 231 , 331 , 432 on the leading edge 1 2 is from about 10 μπ) to about 1 00 μπ). In another example, the thickness of the coating 31 , 231 , 331 , 432 on the leading edge 1 2 is from about 35 μ/η to about 75 μπ). The thickness of the coating 32, 1 32, 231 , 331 on the concave 1 6 and convex side 1 8, for example, is from about 5 μπ) to about 50 μπ). In another example, the thickness of the coating 32, 1 32, 231 , 331 on the concave 1 6 and convex 1 8 sides is from about 15 μ/η ΐο about 35 μπ). The thickness of the metallic bond coat layer 431 , for example, is from about 2.5 μπ) to about 1 0 μπ). The nitrided or carburized depth on the airfoil 14, for example, is from about 10 μ/η ΐο about 50 μηι.

[0069] Fig. 8 is a photograph of an airfoil sample showing erosion of the leading edge of the airfoil due to sand ingestion. In this photograph, the leading edge 1 2 of the airfoil 14 was coated with TiN applied by cathodic arc physical vapor deposition (PVD). As can be seen the Leading Edge Preferential Erosion (LEPER) is present and is detrimental to gas turbine performance. Another airfoil sample showing erosion to the leading edge of the airfoil is shown in Fig. 9. The leading edge 1 2 of the airfoil 14 was treated with TiAIN applied by cathodic arc physical vapor deposition (PVD). As can be seen, Leading Edge Preferential Erosion (LEPER) is present in the edge of the airfoil.

[0070] A series of photographs of erosion test result samples are shown in Fig. 1 0 from testing performed by the University of Cincinnati. In these tests, the leading edges of the airfoil samples were subjected to a particulate applied in a series of stages. In the first stage, 0.995Kg of 95% Arizona Road Dust (ARD) A4 (silica based sand with 80 μιτι nominal diameter) with 5% Mil E-5007C crushed quartz (75-1 00 μιτι) was used. The photographs taken at stage one indicate the amount of erosion that has occurred to the leading edge of the test samples. The samples were subjected to multiple stages of erosion testing including a ninth stage where 1 .1 Kg of ARD A4 was used. The photographs taken at stage nine indicate the amount of erosion that occurred to the leading edge of the test samples. As can be seen, the tungsten carbide tungsten (WC/W) sample applied with the chemical vapor deposition (CVD) method shows a clean edge with no erosion. The coating microstructure is tungsten carbide (WC) particles dispersed in tungsten (W). [0071] In one example, the coatings 31 , 32, 132, 231 , 331 , 431 , 432 may have a hardness of between about 1 ,200 Hv and about 2,00 Hv. In another example, the hardness is between about 1 ,400 Hv and about 1 ,600 Hv.

[0072] In an example, the coatings add about 0.1 % to about 7% additional weight to the gas turbine compressor component. In another example, the coating adds about 0.1 % to about 3% additional weight to the gas turbine compressor component.

[0073] In still yet another example, the coatings 31 , 32, 132, 231 , 331 , 431 , 432 have an exterior surface as shown in Figs. 3-7. In one example, the exterior surface has a roughness of about 3 μίηοΐπβε to about 25 μίηοΐπβε. In another example, the roughness is about 5 μίηοΐπβε to about 15 μίηοΐπβε.

[0074] In one illustrative example, airfoil 14 is made from a metallic substrate. In another example, airfoil 14 is made from one of a stainless steel alloy, a titanium alloy, and a nickel-based alloy.

[0075] While the disclosure has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.

Claims

What is claimed is:

1 . A method for coating a portion of a gas turbine compressor component, the method comprising the steps of

providing a gas turbine compressor component, the component further comprising an airfoil section having an exterior surface and

applying a coating layer to a preselected exterior surface selected from the group consisting of the leading edge surface, the concave side surface, the convex side, and combinations thereof to minimize weight, minimize fatigue debit, and minimize repair costs,

wherein the coating layer is selected from the group consisting of TiAIN, AITiN, TiAIN/TiN multilayer, TiAIN/Cr multilayer, tungsten-tungsten carbide, tungsten carbide cobalt, cobalt-chrome-tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon and

wherein the coating layer at the leading edge surface has a thickness from about 1 0 μπ) to about 1 00 μπ).

2. The method of claim 1 , wherein the coating layer at the leading edge surface has a thickness from about 10 μπ) to about 75 μπ).

3. The method of claim 2, wherein the coating layer at the concave and convex surfaces is from about 5 μπ) to about 50 μπ).

4. The method of claim 1 , further including the step of applying a metallic bond coat layer to the exterior surface of the airfoil before the coating layer.

5. The method of claim 4, wherein the metallic bond coat layer has a thickness from about 2.5 μπ) to about 1 0 μπ).

6. The method of claim 5, wherein the metallic bond coat layer is selected from the group consisting of Ni, Ti, and Cr.

7. The method of claim 1 , further including the step of nitriding the surface of the airfoil.

8. The method of claim 7, wherein the nitrided depth is from about 1 0 μηι to about 50 μπ).

9. The method of claim 1 , further including the step of carburizing the surface of the airfoil.

10. The method of claim 9, wherein the carburized depth is from about 10 μ/η to about 50 μ/η.

1 1 . The method of claim 1 , wherein the coating is applied using coating spray methods from the group consisting of PVD, HVOF, HVAF, solution plasma spray, air plasma spray, cold spray, CVD, electro spark deposition, and PE- CVD.

12. The method of claim 1 1 , wherein the coating powder size is less than 50 μ/η.

13. The method of claim 12, wherein the powder size is less than 20 μ/η.

14. The method of claim 1 , wherein the hardness of the coating layer is between about 1 ,200 Hv and about 2,00 Hv.

15. The method of claim 14, wherein the hardness of the coating layer is between about 1 ,400 Hv and about 1 ,600 Hv.

16. The method of claim 1 , wherein the coating layer adds about 0.1 % to about 7% additional weight to the gas turbine compressor component.

17. The method of claim 16, wherein the coating layer adds about 0.1 % to about 3% additional weight to the gas turbine compressor component.

18. The method of claim 1 , wherein an outer surface of the coating layer has a surface finish of about 3 μίηοΐπβε to about 25 μίηοΐπβε.

19. The method of claim 18, wherein the surface finish is about 5 μίηοΐπβε to about 15 μίηοΐπβε.

20. The method of claim 1 , wherein the gas turbine compressor component is metallic.

21 . The method of claim 20, wherein the gas turbine compressor component is made from one of a stainless steel alloy, a titanium alloy, and a nickel- based alloy.

22. A gas turbine compressor component comprising an airfoil including a leading edge, a concave surface, and a convex surface arranged to face opposite the concave surface,

a first coating applied to the leading edge, and

a second coating applied to the concave surface.

23. The gas turbine compressor component of claim 22, wherein the first coating and the second coating are selected from the group consisting of TiAIN, AITiN, TiAIN/TiN multilayer, TiAIN/Cr multilayer, tungsten-tungsten carbide, tungsten carbide cobalt, cobalt-chrome-tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon.

24. The gas turbine compressor component of claim 23, wherein the first coating is different than the second coating.

25. The gas turbine compressor component of claim 24, wherein the second coating is applied to the convex surface.

26. The gas turbine compressor component of claim 22, further comprising a third coating applied to the convex surface.

27. The gas turbine compressor component of claim 26, wherein the first coating, the second coating, and the third coating are selected from the group consisting of TiAIN, AITiN, TiAIN/TiN multilayer, TiAIN/Cr multilayer, tungsten- tungsten carbide, tungsten carbide cobalt, cobalt-chrome-tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon.

28. The gas turbine compressor component of claim 27, wherein the first coating is different than the second and third coatings.

29. The gas turbine compressor component of claim 27, wherein the second coating is different than the first and third coatings.

30. The gas turbine compressor component of claim 27, wherein the first coating, the second coating, and the third coating are all different.

31 . The gas turbine compressor component of claim 30, wherein the first coating has a thickness from about 1 0 μπ) to about 75 μ/η.

32. The gas turbine compressor component of claim 31 , wherein the coating layer at the concave and convex surfaces is from about 5 μπ) to about 50 μ/η.

33. The gas turbine compressor component of claim 22, wherein the second coating is applied to the leading edge to locate the first coating between the second coating and the leading edge of the airfoil.

34. The gas turbine compressor component of claim 33, wherein the first coating and the second coating are selected from the group consisting of TiAIN, AITiN, TiAIN/TiN multilayer, TiAIN/Cr multilayer, tungsten-tungsten carbide, tungsten carbide cobalt, cobalt-chrome-tungsten carbide, chrome carbide-nickel, chrome carbide-nickel-chrome, and diamond like carbon.

35. The gas turbine compressor component of claim 34, wherein the first coating is different than the second coating.