WO2015071011A1

WO2015071011A1 - Geometrically adapted spraying in coating methods

Info

Publication number: WO2015071011A1
Application number: PCT/EP2014/069892
Authority: WO
Inventors: Andy Borchardt; Tobias Brett; Karsten Klein; Khaled Maiz; Catrina Michel; Alexandr Sadovoy; Martin Witzel
Original assignee: Siemens Aktiengesellschaft
Priority date: 2013-11-14
Filing date: 2014-09-18
Publication date: 2015-05-21
Also published as: DE102013223202A1

Abstract

An equal and improved layer quality on surfaces with a high curvature is achieved due to geometrically adapted spraying.

Description

Geometry-related spray spot adaptation at

Experienced coating

The invention relates to the change of the spray spot in a coating due to locally different geometries of the component to be coated.

In the coating of gas turbine blades, the metallic or ceramic layers are applied with a uniform spray spot, ie with a constant size and shape.

However, it has been found that in certain areas, namely the curved areas, the entrance or other radius areas, this results in different layer properties.

So far, attempts have been made to compensate for this by adapting the relative rotational speed of the component to the coating nozzle.

However, this is very expensive.

It is therefore an object of the invention to provide a method in which such geometric adjustments are better ensured to achieve a consistent microstructure of the coating.

The object is achieved by a method according to claim 1.

In the dependent claims further advantageous measures are listed, which can be combined with each other in order to achieve further advantages.

The advantage of the method lies in the easy-to-control coating method. Show it:

FIG. 1 shows a component with different geometry and the adapted spray spot size or diameter;

2 shows a turbine blade.

The figures and the description represent only embodiments of the invention.

FIG. 1 shows a component 1, 120, 130 (FIG. 2) having a surface 13 which is flat or slightly curved, like a turbine blade 120, 130 the airfoil between leading edge 409 and trailing edge 412, and a strongly curved region 10 The latter is the area around the leading edge 409 in a turbine blade 120, 130.

The difference in the radius of curvature of the flat or slightly curved surface 13 and the more curved surface 10 is at least 10%, in particular at least 20%.

For coating, a thermal coating method may be used, such as plasma spraying, HVOF, cold gas spraying, etc.

With a corresponding coating nozzle 4, from which material emerges in a jet 5 ", in particular powder, a beam spot 7 'with a corresponding focus is produced on the flat or slightly curved surface 13.

If the strongly curved region 10 and the coating nozzle 4 face one another, the spray spot 7 ^{λ λ is} changed. This is preferably the focus or the beam 5 'is changed into a beam spot 7 ^{λ λ} with a smaller extension. The adaptation of the spray spot 7 ^λ , 7 ^{λ λ} , ie the shape, size and intensity can be ensured by in-situ variable burner hardware, such as injectors, process gas distribution.

The intensity is the number and intensity of powder particles in the beam 5 5.

By a modified powder feed, i. At another angle, powder is moved to a different temperature zone of the beam so that the intensity that can be measured by camera systems changes.

In addition, diaphragms can be used or there is a displacement of the coating nozzle 4 in the axial direction at a distance from the surface 13 to be coated.

By using compressed air or inert gas can a

Gas / vacuum flow to be changed.

Likewise, an adaptation of the powder feed and mixing ratios of the powder with the working gases to be varied can take place.

Due to the geometry-dependent adaptation of the spray surface 7 ^λ , 7 ^{λ λ} in the invention in coating processes a consistent improved layer quality is achieved, so that a better durability and longer life of the layer is given during operation.

FIG. 2 shows a perspective view of a moving blade 120 or guide blade 130 of a turbomachine that extends along a longitudinal axis 121.

The turbomachine may be a gas turbine of an aircraft or a power plant for power generation, a steam turbine or a compressor. The blade 120, 130 has along the longitudinal axis 121 consecutively a fastening region 400, a blade platform 403 adjacent thereto and an airfoil 406 and a blade tip 415.

As a guide blade 130, the blade 130 may have at its blade tip 415 another platform (not shown).

In the mounting region 400, a blade root 183 is formed, which serves for attachment of the blades 120, 130 to a shaft or a disc (not shown).

The blade root 183 is designed, for example, as a hammer head. Other designs as Christmas tree or Schwalbenschwanzfuß are possible.

The blade 120, 130 has a leading edge 409 and a trailing edge 412 for a medium flowing past the airfoil 406.

In conventional blades 120, 130, for example, massive metallic materials, in particular superalloys, are used in all regions 400, 403, 406 of the blade 120, 130.

Such superalloys are known, for example, from EP 1 204 776 B1, EP 1 306 454, EP 1 319 729 A1, WO 99/67435 or WO 00/44949.

The blade 120, 130 can be made by a casting process, also by directional solidification, by a forging process, by a milling process or combinations thereof.

Workpieces with a monocrystalline structure or structures are used as components for machines which are exposed to high mechanical, thermal and / or chemical stresses during operation.

The production of such monocrystalline workpieces, for example, by directed solidification from the melt. These are casting processes in which the liquid metallic alloy to monocrystalline structure, ie the single-crystal workpiece, or directionally solidified.

Here, dendritic crystals are aligned along the heat flow and form either a columnar grain structure (columnar, i.e. grains that run the full length of the workpiece and here, in common usage, are referred to as directionally solidified) or a monocrystalline structure, i. the whole workpiece consists of a single crystal. In these processes, one must avoid the transition to globulitic (polycrystalline) solidification, since non-directional growth necessarily forms transverse and longitudinal grain boundaries which negate the good properties of the directionally solidified or monocrystalline component.

If the term generally refers to directionally solidified structures, it means both single crystals that have no grain boundaries or at most small-angle grain boundaries, and stem crystal structures that have grain boundaries running in the longitudinal direction but no transverse grain boundaries. In these second-mentioned crystalline

Structures are also called directionally solidified structures.

Such methods are known from US Pat. No. 6,024,792 and EP 0 892 090 A1.

Likewise, the blades 120, 130 may have coatings against corrosion or oxidation, e.g. M is at least one element of the group iron (Fe), cobalt (Co), nickel (Ni), X is an active element and stands for yttrium (Y) and / or silicon and / or at least one element of the rare ones Earth, or hafnium (Hf)). Such alloys are known from EP 0 486 489 B1, EP 0 786 017 B1, EP 0 412 397 B1 or EP 1 306 454 A1.

The density is preferably 95% of the theoretical

Density.

A protective aluminum oxide layer (TGO = thermal grown oxide layer) is formed on the MCrAlX layer (as an intermediate layer or as the outermost layer). Preferably, the layer composition comprises Co-30Ni-28Cr-8A1-0, 6Y-0, 7Si or Co-28Ni-24Cr-10Al-0, 6Y. In addition to these cobalt-based protective coatings, nickel-based protective layers such as Ni-IOCr-12A1-0.6Y-3Re or Ni-12Co-21Cr-IIAl-O, 4Y-2Re or Ni-25Co-17Cr-10A1-0,4Y-1 are also preferably used , 5Re.

On the MCrAlX may still be present a thermal barrier coating, which is preferably the outermost layer, and consists for example of Zr0 ₂ , Y ₂ 0 ₃ -Zr0 ₂ , that is, it is not, partially or completely stabilized by yttria

and / or calcium oxide and / or magnesium oxide.

The thermal barrier coating covers the entire MCrAlX layer.

By suitable coating methods, e.g. Electron beam evaporation (EB-PVD) produces stalk-shaped grains in the thermal barrier coating.

Other coating methods are conceivable, e.g. atmospheric plasma spraying (APS), LPPS, VPS or CVD. The heat-insulating layer may have porous, micro- or macro-cracked grains for better thermal shock resistance. The thermal barrier coating is therefore preferably more porous than the

MCrAlX layer. Refurbishment means that components

120, 130 may need to be cleared of protective layers (e.g., by sandblasting) after use. This is followed by removal of the corrosion and / or oxidation layers or products. Optionally, even cracks in the component 120, 130 are repaired. This is followed by a re-coating of the component 120, 130 and a renewed use of the component 120, 130.

The blade 120, 130 may be hollow or solid. If the blade 120, 130 is to be cooled, it is hollow and may still film cooling holes 418 (indicated by dashed lines) on.

Claims

claims

1. Procedure

for coating a component (1, 120, 130),

in which a coating nozzle (4) is used,

from which a material flows out in a jet (5 ^λ , 5 ^{λ λ} ) and which produces a spray spot (7 ^λ , 7 ") on the surface (10, 13) of the component (1, 120, 130),

characterized in that

the spray spot (7 ^λ , 7 ^{λ λ} ) and / or the beam (5 ^λ , 5 ^{λ λ} ) is changed in areas (10) with a strongly curved surface,

especially smaller,

especially at least 20%,

especially by 30%.

2. The method according to claim 1,

in which the change of the spray spot (7 ^λ , 7 ") is adjusted by injectors on the coating nozzle (4).

3. The method according to any one of claims 1 or 2, in which a process gas distribution is adjusted.

4. The method according to one or more of the preceding claims,

in which a diaphragm for changing the spray spot (7 ^λ , 7 ") or the beam (5 ^λ , 5 ^{λ λ} ) is used.

5. The method according to one or more of the preceding claims,

in which the coating nozzle (4) is pushed away from the area of the surface (10) in the axial direction.

6. The method according to one or more of the preceding claims,

in which the mixing ratio of outflowing material and working gas is varied.

7. The method according to one or more of the preceding claims,

in which a thermal coating takes place,

in particular HVOF plasma spraying.

8. The method according to one or more of the preceding claims,

in which the size of the spray spot (7 ^λ , 7 ") or the beam (5 ^λ , 5 ^{λ λ} ) is changed.

9. The method according to one or more of the preceding claims,

in which a shape of the spray spot (7 ^λ , 7 ") or the beam (5 ^λ , 5 ^{λ λ} ) with the material from the coating nozzle (4) is changed.

10. The method according to one or more of the preceding claims,

in which the intensity of the spray spot (7 ^λ , 7 ") is changed,

in particular is reduced in the areas (10) with a strongly curved surface.

11. The method according to claim 10,

in which powder is used as the material in the beam (5 ^λ , 5 ^{λ λ} ), and

in which the powder is introduced at a different angle into the temperature zone of the plasma jet or jet,

to change the intensity.

12. The method according to one or more of the preceding claims,

in which compressed air or inert gas is used to change a gas / vacuum flow.

13. The method according to one or more of the preceding claims,

wherein a turbine blade (120, 130) is coated and the highly curved surface (10) is the area around the leading edge (409).