METHOD FOR COATING A COMPONENT

Abstract

The present invention relates to a method for coating a component, wherein the component has a first and a second surface, and wherein the first and the second surface adjoin each other at an edge, in which method i) first of all, the edge between the first and the second surface is rounded, and ii) subsequently, a coating is applied to the first surface.

Claims

1. A method for coating a component wherein the component has a first and a second surface and wherein the first and the second surface adjoin each other at an edge, in which method, comprising the steps of: i) first, rounding the edge between the first and second surfaces is rounded, and ii) subsequently, applying a coating is applied to the first surface.

2. The method according to claim 1, in which wherein a rounding introduced in step i) between the first and second surfaces has, as viewed in section, a radius of curvature R that corresponds to at least 0.5 times a thickness d of the coating that is, R≥0.5.Math.d.

3. The method according to claim 1, wherein a rounding introduced in step i) between the first and second surfaces has, as viewed in a section, a radius of curvature R that corresponds to at most 5 times a thickness d of the coating, that is, R≤5.Math.d.

4. The method according to claim 1, wherein the first surface is processed in a material-removing manner prior to step i) and the edge is thereby produced.

5. The method according to claim 1, wherein the rounding of the edge in step i) comprises a processing with a brush.

6. The method according to claim 5, wherein, in step i), after the processing with the brush, a grinding processing occurs.

7. The method according to claim 1, wherein the coating is applied in a galvanic manner in step ii).

8. The method according to claim 1, wherein the coating contains boron nitride.

9. The method according to claim 1, wherein the component is a blade body for a turbomachine.

10. The method according to claim 9, wherein the first surface is a blade tip surface and the second surface is a side surface of the blade body.

11. A method for producing a component for a turbomachine, wherein the component is coated in a method in accordance with claim 1.

12. A component for a turbomachine, produced in a method according to claim 11, wherein the coating applied to the first surface, as viewed in section, is at most flush with the second surface, that is, it does not overhang laterally.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The invention is described in detail below on the basis of exemplary embodiments, whereby the individual features in the scope of the dependent claims can also be a key part of the invention in another combination and, here, too, no distinction is made in detail between the different claim categories.

[0019] Shown in detail are:

[0020] FIG. 1: a turbomachine, namely, a turbofan engine in a schematic longitudinal section;

[0021] FIG. 2: a rotating blade in a schematic overview depiction;

[0022] FIG. 3: a detail view for illustration of a coating applied to the blade tip of the rotating blade in accordance with FIG. 2;

[0023] FIG. 4 a comparative depiction of a coating that is not in accordance with the invention;

[0024] FIG. 5 a rotating blade as part of a blisk.

DESCRIPTION OF THE INVENTION

[0025] FIG. 1 shows a turbomachine 1, specifically a turbofan engine, in an axial section. The turbomachine 1 is functionally divided into a compressor 1a, a combustion chamber 1b, and a turbine 1c. Both the compressor 1a and the turbine 1c are each constructed of a plurality of stages, with each stage composed of a guide vane ring and a following rotating vane ring. In the compressor 1a, the inflow air is compressed and then undergoes combustion with admixed kerosene in the downstream combustion chamber 1b. The present subject is directed, in particular, at a rotating blade, which, in general, can also find application in the turbine 1c, but, in particular, in the compressor 1a.

[0026] FIG. 2 shows a component 10, namely, a rotating blade body 21 of a rotating blade 20, which, in addition, has a blade root 22, in a schematic axial view. The rotating blade 20 is mounted with the blade root 22 in a disk, which is not depicted here, and, in operation, rotates in a direction of rotation 25. The blade body has two side surfaces 23, namely, a suction side surface 23.1 and a pressure side surface 23.2. A coating 30 is applied to a blade tip surface 24 and serves for running-in in a run-in lining 31, which is indicated here only schematically.

[0027] FIG. 3 shows the blade tip surface 24 with the coating 30 in a detail view. The coating 30 is applied by electrochemical deposition of a metal matrix, preferably nickel with the incorporation of particles of hard material, preferably boron nitride. The blade tip surface 24 presents a first surface 41, which is coated, whereas the side surfaces 23 are second surfaces 42 and remain uncoated. Prior to the application of the coating, the blade tip surface 24 is ground, as a result of which a sharp edge 35 with respect to the second surfaces 42 is created in each instance. This edge is rounded prior to the application of the coating 30, which, in the present case, takes place through a combination of brushing and subsequent grinding. In this way, during the subsequent galvanic deposition, a concentration of electric field lines is prevented, so that no excess application of material is found there, nor does the coating 30 overhang laterally. The respective rounding 36 is adjusted in such a way that the respective radius of curvature R corresponds approximately to the thickness d of the coating 30.

[0028] FIG. 4 shows, for comparison, a blade tip surface 24 that is not coated in accordance with the invention. The coating 30 overhangs laterally opposite side surfaces 23, which can be detrimental in terms of structural mechanics. Thus, for example, under high-frequency alternating load, in particular under a vibrational load in the blade tip region 24, cracks form in the coating 30 and propagate from there into the blade body 21. This crack initiation can be promoted by crystalline boron nitride, which is indicated here schematically.

[0029] FIG. 5 shows a design of the rotating blade 20 that is an alternative to FIG. 2, namely, as part of a so-called blisk 50 (blade-integrated disk). In this case, the blade bodies 21 of the rotating blades 20 are provided on the disk 51 in an integral manner. What is involved here, therefore, is an integral part (of which only an excerpt is shown in FIG. 5). The blade tip surfaces 24 of the blade bodies 21 are thereby each furnished with a coating 30; see the above detailed description.