SEALING FIN ARMORING AND METHOD FOR THE PRODUCTION THEREOF

Abstract

A method for coating a sealing fin (2) on a component of a turbomachine, in particular on a blade tip (6) of a blade (1) of a turbomachine, with armoring (3, 30, 300), and to a corresponding component, in which method a blade (1) having at least one sealing fin (2) and a slurry which comprises particles of MCrAlY or particles for forming an MCrAlY layer (31), where M is nickel and/or cobalt, are provided, the slurry is applied onto the sealing fin and dried, and the sealing fin with the applied slurry is subjected to an aluminizing process so that the MCrAlY layer comprises an Al-rich sublayer (32).

Claims

1. A method for coating a sealing fin on a component of a turbomachine with armoring, in which method a blade having at least one sealing fin is provided and wherein the method comprises applying onto the sealing fin a slurry which comprises particles of MCrAlY or particles for forming an MCrAlY layer, where M represents nickel and/or cobalt, and aluminizing the sealing fin having the slurry applied thereon.

2. The method of claim 1, wherein a sealing fin on a blade tip of a blade of a turbomachine is coated.

3. The method of claim 1, wherein the slurry comprises hard material particles.

4. The method of claim 1, wherein the method further comprises depositing a hard material layer on the coating following the aluminizing.

5. The method as claimed in claim 4, wherein depositing the hard material layer is carried out by one or more of spraying, thermal spraying, flame spraying, high-velocity flame spraying, electric arc spraying, cold gas spraying, detonation spraying, laser spraying, and plasma spraying.

6. The method of claim 4, wherein the hard material layer is formed from aluminum oxide and/or titanium oxide.

7. The method of claim 5, wherein the hard material layer is formed from aluminum oxide and/or titanium oxide.

8. The method of claim 3, wherein the hard material particles comprise at least one substance selected from oxides, carbides, nitrides,

9. The method of claim 3, wherein the hard material particles comprise at least one of boron nitride, cubic boron nitride, aluminum oxide, titanium oxide, titanium carbide, tungsten carbide, chromium carbide, zirconium oxide.

10. The method of claim 1, wherein the method further comprises drying the slurry before aluminizing, and/or wherein aluminizing is carried out with an activator which contains halogen.

11. The method of claim 1, wherein aluminizing is carried out with an activator which contains halogen.

12. The method of claim 1, wherein the particles of MCrAlY or particles for forming an MCrAlY layer have a particle size of from about 1 m to 200 m.

13. The method of claim 1, wherein the particles of MCrAlY or particles for forming an MCrAlY layer have a particle size of from about 5 m to 120 m.

14. The method of claim 10, wherein the slurry is dried at a temperature of from about 100 C. to 200 C.

15. The method of claim 10, wherein the slurry is dried at a temperature of from about 120 C. to 150 C.

16. A component of a turbomachine, which component comprises at least one sealing fin on a blade tip of a blade, wherein the at least one sealing fin comprises armoring which comprises an MCrAlY layer, where M represents nickel and/or cobalt, a hard material layer being present on the MCrAlY layer and an Al-rich layer being present in an interface region between the MCrAlY layer and the hard material layer.

17. The component of claim 16, wherein the blade comprises a plurality of sealing fins on the at least one blade tip.

18. The component of claim 16, wherein the hard material layer is formed from aluminum oxide and/or titanium oxide.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The appended drawings show, purely schematically, in

[0033] FIG. 1 a partial longitudinal section along the rotation axis of a turbomachine,

[0034] FIG. 2 a partial section through a sealing fin according to a first embodiment of the invention, and in

[0035] FIG. 3 a partial section through a sealing fin according to a second embodiment of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0036] The particulars shown herein are by way of example and for purposes of illustrative discussion of the embodiments of the present invention only and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the present invention. In this regard, no attempt is made to show details of the present invention in more detail than is necessary for the fundamental understanding of the present invention, the description in combination with the drawings making apparent to those of skill in the art how the several forms of the present invention may be embodied in practice.

[0037] FIG. 1 shows a detail of a turbomachine in a longitudinal section along the rotation axis of the turbomachine. In the detail shown, a rotor blade 1 can be seen which extends both in the axial x direction along the rotation axis of the turbomachine and in the radial direction r, the axial direction x and the radial direction r being shown by corresponding arrows.

[0038] The rotor blade 1 is arranged next to a multiplicity of rotor blades (not shown) which are arranged around a rotation shaft, so that during operation of the turbomachine the rotor blade 1 rotates about a rotation axis parallel to the axial direction. The fluid of the turbomachine flows in the axial direction through a flow channel, which is bounded by a housing 5. In order to use as far as possible all the flowing fluid, the gap between the blade tip 6 and the housing 5 should be kept as small as possible. In order to compensate for the variations of the gap width due to different thermal conditions, pressure conditions and operating conditions, a plurality of sealing fins 2 are provided on the blade tip 6 of the blade 1, which protrude from the blade tip 6 in the radial direction at a distance from one another and extend in the circumferential direction along the blade tip 6 about the rotation axis of the turbomachine Arranged opposite the sealing fins 2, there is a running-in coating 4, for example in the form of a honeycomb structure, the running-in coating 4 being arranged on the housing 5. The sealing fins 2 are configured in such a way that they bed into the running-in coating 4 in order to form a so-called labyrinth seal. In order to avoid wear of the sealing fins 2 and increase the lifetime of the blade, or rotor blade, the sealing fins 2 comprise armoring 3 which improves the wear resistance during bedding of the sealing fins 2 into the running-in coating 4.

[0039] FIG. 2 shows, in a cross section through a sealing fin 2, one embodiment of armoring 30 such as is used for the armoring 3 of the rotor blade 1 of FIG. 1. The armoring 30 comprises an MCrAlY base layer 31, which has been deposited on the sealing fin 2 by the slurry process described above. in the edge region of the MCrAlY base layer, an aluminum-rich sublayer 32 is formed, which has been formed by an aluminizing process, for example gas-phase aluminizing with an activator containing halogen, for example an activator containing fluorine or chlorine. Preferably, the aluminum-rich sublayer 32 was generated simultaneously with the diffusion anneal of the slurry for forming the MCrAlY layer 31, during which the slurry comprising MCrAlY particles or corresponding particles for forming MCrAlY layers, which is applied in the liquid or paste form, was exposed after drying to a suitable heat treatment in order to form the MCrAlY layer by diffusion processes. During the combined diffusion anneal treatment with aluminizing to form the MCrAlY layer enriched with aluminum in the edge region, an aluminum donor and one or more activator substances for the gas-phase aluminizing are provided in a correspondingly configured treatment chamber, so that aluminum can be enriched in a sublayer 32 of the edge region of the MCrAlY layer 31. In order to avoid aluminizing of the sealing fin 2, the latter may be covered during the diffusion anneal and the aluminizing

[0040] A hard material layer, for example an oxide-ceramic layer comprising titanium oxide and aluminum oxide is applied by means of a spraying method, for example thermal spraying or plasma spraying, onto the MCrAlY base layer 31 formed in this way with the aluminum-rich sublayer 32. The sprayed hard material layer 33 may for example he applied, by two coating sources arranged correspondingly at an angle, in such a way that the hard material layer 33 is formed axially increasingly in the radial direction r, so that a wedge-shaped hard material layer 33 that increases in its width in the radial direction is formed.

[0041] FIG. 3 shows a second embodiment of armoring 300 on a sealing fin 2, which was likewise formed by means of the slurry process described above. The armoring 300 comprises an MCrAlY base layer 301, which differs from the MCrAlY base layer 31 of the embodiment of FIG. 2 in that hard material particles 302, for example particles of boron nitride, tungsten carbide, aluminum oxide, titanium oxide or the like, are incorporated in the MCrAlY base layer 301.

[0042] This is achieved by virtue of the fact that hard material particles which are incorporated in the thus formed MCrAlY base layer 301 after drying of the slurry and the diffusion annealing for layer formation are additionally incorporated in the liquid or pasty slurry comprising MCrAlY particles or particles which can form an MCrAlY layer.

[0043] As during the production of the MCrAlY base layer 31 of the exemplary embodiment of FIG. 2, the diffusion anneal for producing the MCrAlY base layer 301 of the exemplary embodiment of FIG. 3 may be associated simultaneously with an aluminizing process by an aluminum donor material and corresponding activators, for example activators containing halogen, being provided in a treatment chamber at least during a part of the diffusion anneal, in order to cause aluminizing of the edge layer of the MCrAlY base layer. Correspondingly, the armoring 300 comprises an aluminum-rich sublayer 303 in the edge region of the MCrAlY base layer 301, which increases the oxidation resistance of the sealing fin 2 comprising the armoring 300.

[0044] Although the present invention has been described in detail with the aid of the exemplary embodiments, it is clear to the person skilled in the art that the invention is not restricted to these exemplary embodiments, but rather that variants are possible in that individual features may be omitted or other combinations of features may be implemented, so long as the protective scope of the appended claims is not departed from. The present disclosure also includes all combinations of the individual features proposed.

LIST OF REFERENCE NUMBERS

[0045] 1 blade [0046] 2 sealing fin [0047] 3 armoring [0048] 4 running-in coating [0049] 5 housing [0050] 6 blade tip [0051] 30 armoring [0052] 31 MCrAlY base layer [0053] 32 aluminum-rich sublayer [0054] 33 hard material layer [0055] 300 armoring [0056] 301 MCrAlY base layer [0057] 302 hard material particles [0058] 303 aluminum-rich sublayer