Corrosion- and erosion-resistant coating for turbine blades of gas turbines

Abstract

A component of a turbine, in particular a gas turbine, wherein the component has a coating for increasing the erosion and corrosion resistance, wherein the coating is preferably applied directly to the component, wherein the coating consists of a functional layer and an intermediate layer, wherein the intermediate layer is arranged between the turbine blade substrate and the functional layer and wherein the functional layer consists of the elements Al, Cr, O and N.

Claims

1. A component of a gas turbine, wherein the component has a coating for increasing erosion and corrosion resistance, wherein the coating is applied directly to the component, and the coating consists of a functional layer and an intermediate layer, wherein the intermediate layer is arranged between the turbine blade substrate and the functional layer, the functional layer consists of the elements Al, Cr, O and N, and the intermediate layer comprises a layer system made of a single layer of Cr, a single layer of AlCr, and a single layer of Al—Cr—O in this order.

2. The component according to claim 1, wherein the functional layer is a monolayer or a multilayer.

3. The component according claim 2 wherein the functional layer comprises a multilayer structure in which an Al/Cr ratio, an O/N ratio, or a combined Al/Cr and O/N ratio changes periodically over at least part of a layer thickness, aperiodically over at least part of the layer thickness, or both periodically and aperiodically over at least part of the layer thickness.

4. The component according to claim 3 wherein the ratio of Al to Cr (Al/Cr) atoms in the functional layer is between 4 and 1.

5. The component according to claim 3 wherein the ratio of O to N atoms (O/N) in the functional layer is between 0.2 and 1.5.

6. The component according to claim 3 wherein the functional layer has an indentation hardness of at least 25 GPa.

7. The component according to claim 3 wherein the functional layer has a modulus of elasticity of at least 280 GPa.

8. The component according to claim 3 wherein, in addition to cubic CrN and cubic AlN peaks in X-ray diffraction, the functional layer also has additional peaks of at least one oxide.

9. The component according to claim 8 wherein at least one of the additional peaks is a peak of a hexagonal phase.

10. A method for producing the component according to claim 1 comprising using cathodic spark evaporation, a sputtering method, or both cathodic spark evaporation and a sputtering method for its production and first depositing the intermediate layer that includes a single layer of Cr, a single layer of AlCr, and a single layer of Al—Cr—O in this order, directly on a cleaned surface of the component and depositing the functional layer consisting of the elements Al, Cr, O and N directly thereafter.

11. The method according to claim 10, wherein the surface to be coated is selected from the group consisting of a high-chrome steel surface, a Ni—Cr-containing surface, a Ni—Co-containing surface, a Ni—Cr—Co-containing surface, a surface containing one or more super alloys, an aluminide-containing surface, and combinations thereof.

Description

PREFERRED EMBODIMENTS

(1) The invention will now be explained in detail on the basis of different embodiments and by means of the figures.

(2) FIG. 1 shows the X-ray spectrum of the functional layer of a layer according to the invention.

(3) FIG. 2 schematically shows the layer structure of a first embodiment A of the present invention with the structure: substrates/Cr/AlCr/AlCrO/Al—Cr—O—N, the outermost layer being a monolayer.

(4) FIG. 3 schematically shows the layer structure of a second embodiment B of the present invention, with the structure: substrates/Cr/AlCr/AlCrO/Al—Cr—O—N, the outermost layer being a multilayer composed of a plurality of individual layers according to the invention, which together form the outer functional layer.

(5) FIG. 4 schematically shows the layer structure of a third embodiment C of the present invention with the structure: substrates/AlCr/AlCrO/Al—Cr—O—N, the outermost layer being a monolayer.

(6) FIG. 5 shows a calotte grinding of a layer system according to the third embodiment.

(7) FIG. 6 shows the cross section of a layer system according to the third embodiment in an SEM image.

(8) FIG. 7 schematically shows the layer structure of a fourth embodiment D of the present invention with the structure: substrates/AlCr/AlCrO/Al—Cr—O—N, the outermost layer being a multilayer.

(9) FIG. 8 shows the comparison between a conventional component, referred to as TurbinPro and coated with TiAlN, with embodiment C in the salt spray test. TurbinPro is a commercially available coating product from Oerlikon Surface Solutions AG, Switzerland.

(10) FIG. 9a shows the resistance to solid-state erosion for a particle incidence angle of 90° for different surfaces.

(11) FIG. 9b shows the resistance to solid-state erosion for a particle incidence angle of 20° for different surfaces.

(12) FIG. 10 shows the chemical composition of an example of a layer system according to the invention.

(13) The layer system according to the invention (embodiments A to D) is applied to the component (gas turbine blade) by means of PVD. Variants A and B have an additional Cr-containing layer interface to the substrate, while variants C and D do without this interface. The erosion resistance (solid particle erosion test according to ASTM G76) —and corrosion resistance (e.g. salt spray test according to DIN EN ISO 9227) are optimized via the proportion of oxygen in the Al—Cr—O—N layer. For erosion resistance, the minimum values of layer hardness and modulus of elasticity are decisive, for corrosion protection the minimum oxygen content in the layer is decisive.

MISCELLANEOUS

(14) Basically it should be said that completely independent of the already established claims, but also in combination with it, protection is also claimed for a component that has the characteristics of one of the following paragraphs:

(15) Component of a turbine, in particular a gas turbine, wherein the component can be, for example, a turbine blade and the component has an erosion and corrosion resistant coating, wherein the component is characterized in that the coating is applied to a component substrate and comprises a functional layer and an intermediate layer which is arranged between the turbine blade substrate and the functional layer (paragraph 1).

(16) Component according to the preceding paragraph 1, wherein the component is characterized in that the intermediate layer comprises a layer system made of Cr and/or AlCr and/or Al—Cr—O.

(17) Component according to the immediately preceding paragraph 2, wherein the component is characterized in that the intermediate layer consists of a layer system of AlCr and Al—Cr—O.

(18) Component according to the preceding paragraph 2, wherein the component is characterized in that the functional layer essentially comprises the elements Al, Cr, O and N.

(19) Component according to one of the preceding paragraphs of this chapter, wherein the component is characterized in that the functional layer is a monolayer or a multilayer.

(20) Component according to paragraph 5, wherein the component is characterized in that the functional layer comprises a multilayer structure in which the Al/Cr ratio and/or the O/N ratio change periodically over at least part of the layer thickness and/or aperiodically over at least part of the layer thickness.

(21) Component according to paragraph 5, wherein the component is characterized in that the ratio of Al to Cr (Al/Cr) atoms in the functional layer is between 4 and 1, preferably between 2 and 1.5.

(22) Component according to paragraph 5, wherein the component is characterized in that the ratio of O to N atoms (O/N) in the functional layer is between 0.2 and 1.5, preferably between 0.4 and 1.

(23) Component according to paragraph 5, wherein the component is characterized in that the functional layer has an indentation hardness of at least 25 GPa, preferably greater than 30 GPa.

(24) Component according to paragraph 5, wherein the component is characterized in that the functional layer has a modulus of elasticity of at least 280 GPa, preferably greater than 300 GPa.

(25) Component according to paragraph 5, wherein the component is characterized in that, in addition to the cubic CrN and cubic AlN peaks in X-ray diffraction, the functional layer also has additional peaks of at least one oxide.

(26) Component according to paragraph 11, wherein the component is characterized in that at least one of the additional peaks is the peak of a hexagonal phase (such as eskolaite and/or corundum).

(27) A method for producing a component or a coating according to paragraph 1, wherein the method is characterized in that cathodic spark evaporation and/or a sputtering method is used for its production.

(28) Method according to paragraph 13, wherein the surface to be coated is a high-chrome steel surface and/or a Ni—Cr, Ni—Co, Ni—Cr—Co containing substrate surface and/or a substrate surface containing one or more super alloys, preferably an aluminide containing (Al—Ni, Al—Ti, Al—Hf) substrate surface.