WO2008049460A1

WO2008049460A1 - Method for adjusting the surface roughness in a low temperature coating method, and component

Info

Publication number: WO2008049460A1
Application number: PCT/EP2006/067726
Authority: WO
Inventors: Werner Stamm
Original assignee: Siemens Aktiengesellschaft
Priority date: 2006-10-24
Filing date: 2006-10-24
Publication date: 2008-05-02

Abstract

Low temperature coating methods still have not been sufficiently optimized for the production of layer systems. The method according to the invention proposes to adjust the impact angle (16) of the particle stream (22) and the surface (3) of the component (1, 120, 130) to be coated in a controlled manner in order to obtain a desired surface roughness.

Description

Method for adjusting the surface roughness in low-temperature coating methods and component

The invention relates to a method for adjusting the roughness in low-temperature coating method and a component according to claim 14.

In known coating methods often only the powder rate is varied.

This leads to some coating processes, such as the low temperature coating process, such as low temperature coating. HVOF or cold gas spraying to suboptimal coating results.

It is therefore the object of the invention to provide a method which controls the surface roughness on components which are coated by means of low-temperature processes.

The object is achieved by a method according to claim 1 and a component according to claim 14.

The measures listed in the dependent claims represent further advantageous improvements, which can also be combined with each other in an advantageous manner.

Show it:

Figure 1, 2 is a schematic arrangement of the component and the

Beschichtungsduse Figure 3 - 6 Exemplary embodiment Figure 7 shows a gas turbine,

FIG. 8 shows in perspective a turbine blade, FIG. 9 shows in perspective a combustion chamber. FIG. 1 shows a turbine blade 120, 130 (FIGS. 7, 8) or in general a component 1, which is coated by means of a nozzle 13.

In the case of components for turbine components, e.g. Combustor 155 (FIG. 9), turbine runner 120, or vanes 130 use nickel- or cobalt-based superalloys, which are provided with corrosion and / or oxidation protection layers, such as carbon black. MCrAlX

Coatings are provided. Such a corrosion and / or oxidation protection layer may represent an outermost layer (overlay) or serve as an intermediate layer for an outer ceramic heat-insulating layer.

For overlays (Figure 6), a fine surface roughness is preferably required, whereas for thermal dam layers applied by plasma spraying (APS, VOPS, LPPS) on the underlying layer a rough surface roughness is advantageous as compared to "overlay" However, a less rough or fine interlayer is for EB-PVD coated ceramic layers such as yttria stabilized zirconia (YSZ) or PVD or CVD. necessary (Fig. 4).

A nozzle 13 generates with a coating material a particle stream 22 which impinges on the surface 3 of the component 1, 120, 130, 155 at a certain angle of incidence α. The nozzle 13 and / or the component 1, 120, 130, 155 can preferably be pivoted accordingly.

This angle of incidence α is set at about 90 °, ie 90 ° + 2 °, in particular at 90 °, in order to produce coarse surface roughness in low-temperature processes such as HVOF (high velocity oxy fuel) or cold gas spraying. The angle of incidence α can be related to the surface 3 of the component 1, 120, 130, 155 or to the longitudinal axis 121. Low-temperature process means that the coating material does not melt. The component to be coated (substrate) can be additionally heated, but not so strong that the impinging coating material melts.

The method is preferably carried out with metallic layers.

If fine surface roughness is required, an angle distinctly different from 90 °, in particular ≦ 80 °, is set. The lower limit here is 45 °. Again, this is preferably done with metallic layers.

For measuring the surface roughness, any known measure of roughness can be used. The difference between "coarse" and "fine" is at least 20%, especially at least 30%.

In particular, in a transition 19 between the airfoil 406 and the platform 403 or for the platform 40, an angle of incidence α of 90 ° + 2 ° is set. Therefore, in such components 1, 120, 130, the greater part of the

Blade sheet 406 coated at the predetermined angle α. Thus, if an impact angle α of about 90 ° is desired, this is done for most of the airfoil 406 and an impact angle α <80 ° is set in the transition 19 and / or on the blade form 403 (shown schematically in FIG. 5). The blade 120 may be coated to the blade tip 415 and / or the blade tip 415 may be coated at an impact angle of about 90 °. Accordingly, in the case of a guide blade 130 in which two platforms 403, 403 '(FIG. 2) are present, likewise only a partial region 27 of the blade 406 is coated with an impact angle α. Here, therefore, there is another transition 19 'conditioned by another platform 403'. So if rough roughness is required, the largest part 27 of the blade 406 is coated so that an angle of incidence of 90 ° is present.

If low roughness is required in the component according to FIG. 1 or FIG. 2, this can be set for the entire surface to be coated 403, 403 ', 406, 415 by the angle of incidence α <90 °.

FIG. 3 shows a substrate of a component 1, 120, 130, 155, on which an intermediate layer 43 is applied. The intermediate layer 43 has a rough surface roughness on which an outer layer 46 is then applied. The intermediate layer 43 is preferably metallic, whereas the outer layer 46 is ceramic. Particularly in the case of plasma-sprayed ceramic layers, a coarse surface roughness of the underlying layer 43 is necessary.

In Figure 4, a similar layer structure as shown in Figure 3, but wherein the surface roughness of the intermediate layer 43 by the angle α <90 ° was set so that a fine surface roughness is present, so that a flat or evenly distributed comparable growth conditions for a EB-PVD layer is given.

FIG. 5 once again schematically shows that the intermediate layer has two different surface areas, here identified by 406, 19, which have different surface roughnesses. In Figure 6, a component 1, 120, 130, 155 is shown, wherein the layer 43 produced by the method represents the outermost layer having a fine surface roughness.

The method is not applicable to PVD, CVD or galvanic processes, and plasma spraying (APS, LPPS, VPS) is to be excluded from the invention. On the other hand, these methods can be used as a subsequent coating method

FIG. 7 shows by way of example a gas turbine 100 in a long partial section. The gas turbine 100 has inside a rotatably mounted about a rotation axis 102 rotor 103 with a shaft 101, which is also referred to as a turbine runner.

Along the rotor 103 follow one another Ansauggehause 104, a compressor 105, for example, a toroidal combustion chamber 110, in particular annular combustion chamber, with a plurality of coaxially arranged burners 107, a turbine 108 and the exhaust housing 109th

The annular combustion chamber 110 communicates with an annular annular hot gas channel 111, for example. There, for example, four turbine stages 112 connected in series form the turbine 108.

Each turbine stage 112 is formed, for example, from two blade rings. In the direction of flow of a working medium 113, a series of guide vanes 115 follows a series of vanes 120 in the hot gas duct 111 of a row of vanes 115.

In this case, the guide vanes 130 are fastened to an inner housing 138 of a stator 143, whereas the rotor blades 120 of a row 125 are attached to the rotor 103 by means of a turbine disk 133, for example.

Coupled to the rotor 103 is a generator or work machine (not shown). During operation of the gas turbine 100, air 105 is sucked in and compressed by the compressor 105 through the intake housing 104. The compressed air provided at the turbine-side end of the compressor 105 is supplied to the burners 107 where it is mixed with a fuel. The mixture is then burned to form the working fluid 113 in the combustion chamber 110. From there, the working medium 113 flows along the hot gas channel 111 past the guide vanes 130 and the rotor blades 120. The working medium 113 expands on the rotor blades 120 in a pulse-transmitting manner, so that the rotor blades 120 drive the rotor 103 and this drives the working machine coupled to it ,

The components exposed to the hot working medium 113 are subject to thermal loads during the operation of the gas turbine 100. The guide vanes 130 and rotor blades 120 of the first turbine stage 112, viewed in the direction of flow of the working medium 113, are subjected to the greatest thermal stress in addition to the heat shield elements lining the annular combustion chamber 110.

In order to withstand the temperatures prevailing there, they can be cooled by means of a coolant. Likewise, substrates of the components may have a directional structure, i. they are monocrystalline (SX structure) or have only slow grains (DS structure).

As the material for the components, in particular for the turbine blade 120, 130 and components of the combustion chamber 110, for example, iron-, nickel- or cobalt-based superalloys are used. 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; These documents are part of the disclosure regarding the chemical composition of the alloys.

On the MCrAlX may still be present a thermal insulation layer, and consists for example of Zrθ ₂ , Y ₂ θ3 Zrθ ₂ , that is, it is not, partially or completely stabilized by yttria and / or calcium oxide and / or magnesium oxide. Suitable coating processes, such as electron beam evaporation (EB-PVD), are used to produce protuberant grains in the thermal insulation layer.

The vane 130 has a Leitschaufelfuß facing the Innengehause 138 of the turbine 108 (not shown here) and a Leitschaufelfuß the opposite vane head on. The vane head faces the rotor 103 and fixed to a mounting ring 140 of the stator 143.

FIG. 8 shows a perspective view of a moving blade 120 or guide blade 130 of a flow machine, which extends along a longitudinal axis 121 and which are coated by means of the method according to the invention.

The flow machine may be a gas turbine of an aircraft or a power plant to produce electricity, a steam turbine or a compressor.

The blade 120, 130 has along the longitudinal axis 121 in succession a fastening region 400, an adjacent blade platform 403 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 fir tree or Schwäbwschwanzfuß are possible.

The blade 120, 130 has a flow-on edge 409 and a downstream edge 412 for a medium that flows past the blade 406. In conventional blades 120, 130, for example, solid 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; These documents are part of the disclosure regarding the chemical composition of the alloy. The blade 120, 130 can be made by a casting process, also by directional solidification, by a forging process, by a Frasverfahren or combinations thereof.

Single-crystalline structures or structures are used as components for machines that are subject to high mechanical, thermal and / or chemical stresses during operation. The production of such monocrystalline workpieces takes place, for example. by directed solidification from the melt. These are casting processes in which the liquid metallic alloy is transformed into a monocrystalline structure, i. to the single-crystal workpiece, or directionally solidified. Here, dendritic crystals are aligned along the warm flow and form either a prismatic crystalline

Grain structure (columnar, i.e. grain which run the whole length of the workpiece and here, in common usage, are referred to as directionally solidified) or a monocrystalline structure, i. The whole work consists of a single crystal. In these processes, it is necessary to avoid the transition to globulitic (polycrystalline) solidification, since non-directional growth necessarily produces transverse and longitudinal grain boundaries which negate the good properties of the directionally solidified or monocrystalline component.

Is generally speaking of directionally solidified Gefugen, so they are both single crystals meant that have no grain boundaries or at most small angle grain boundaries, as well Stangelkristallstrukturen, which probably have in the longitudinal direction extending grain boundaries, but no transverse grain boundaries. These second-mentioned crystalline structures are also known as directionally solidified structures.

Such methods are known from US Pat. No. 6,024,792 and EP 0 892 090 A1; these writings are part of the revelation regarding the solidification process.

Likewise, the blades 120, 130 coatings, in particular applied with the inventive method, against corrosion or oxidation, for. 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, which should be part of this disclosure with regard to the chemical composition of the alloy. The density is preferably 95% of the theoretical density.

On the MCrAlX layer (as an intermediate layer or as outermost layer), a protective aluminum oxide layer (TGO = thermal grown oxide layer) is formed.

On the MCrAlX can still be a Warmedammschicht be present, which is preferably the outermost layer, and consists for example of ZrO ₂ , Y ₂ O ₃ -ZrO ₂ , ie it is not, partially ^¬ or fully stabilized by yttria and / or calcium oxide and / or magnesium oxide.

The thermal insulation layer covers the entire MCrAlX layer. Suitable coating processes, such as electron beam evaporation (EB-PVD), are used to produce protuberant grains in the thermal insulation layer. Other coating methods are conceivable, for example atmospheric plasma spraying (APS), LPPS, VPS or CVD. The thermal insulation layer may have porous, micro- or macro-cracked grains for better thermal shock resistance. The Warmedammschicht is therefore preferably more porous than the MCrAlX layer.

Refurbishment means that components 120, 130 may need to be deprotected after use (e.g., by sandblasting). 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, in particular using the method according to the invention and a renewed use of the component 120, 130.

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

FIG. 9 shows a combustion chamber 110 of a gas turbine.

The combustion chamber 110 is designed, for example, as a so-called annular combustion chamber, in which a multiplicity of burners 107 arranged in the circumferential direction around a rotation axis 102 pass into a common combustion chamber space 154, which produce flames 156. For this purpose, the combustion chamber 110 is configured in its entirety as an annular structure, which is positioned around the axis of rotation 102 around.

To achieve a comparatively high efficiency, the combustion chamber 110 is designed for a comparatively high temperature of the working medium M of about 1000 ^° C. to 1600 ^° C. In order to allow a comparatively long service life for these unfavorable operating parameters for the materials, the combustion chamber wall 153 is provided on its side facing the working medium M with an inner lining formed of heat shield elements 155, which are coated with the method according to the invention. Each heat shield element 155 made of an alloy is equipped on the working medium side with a particularly heat-resistant protective layer (MCrAlX layer and / or ceramic coating) or is made of high-temperature-resistant material (solid ceramic blocks).

These protective layers may be similar to the turbine blades, so for example MCrAlX means: 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 earths, 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, which should be part of this disclosure with regard to the chemical composition of the alloy.

On the MCrAlX an example, ceramic maintenance, may be medammschicht, consisting for example of ZrO> 2, ZrO 2 Y2Ü3-ie, it is not partially full text or ^¬ dig stabilized by yttrium oxide and / or calcium and / or magnesium oxide.

By suitable coating methods, e.g. Electron Beam Evaporation (EB-PVD) produces proton grains in the thermal insulation layer. Other coating methods are conceivable, e.g. atmospheric plasma spraying (APS), LPPS, VPS or CVD. The thermal insulation layer may have porous, micro- or macro-cracked grains for better thermal shock resistance.

Refurbishment means that heat shield elements 155 may be replaced after use by heat shielding elements 155

Protective layers must be freed (eg by sandblasting). This is followed by removal of the corrosion and / or oxidation layers or products. If necessary, cracks in the heat shield element 155 are also repaired. This is followed by a recoating of the heat shield elements 155 and a renewed use of the heat shield elements 155. Due to the high temperatures in the interior of the combustion chamber 110, a cooling system can additionally be provided for the heat shield elements 155 or for their holding elements. The heat shield elements 155 are then, for example, hollow and possibly still have cooler holes (not shown) which still touch the combustion chamber space 154.

Claims

claims

1. Method for adjusting the surface roughness in low-temperature coating processes of components (1,

120, 130, 155), in particular in HVOF or cold gas spraying, in which the angle of incidence (α) of a particle stream (22) of a coating material on the surface (3) of the component (1, 120, 130, 155) 90 ° + 2 ° , in particular 90 °, amounts to produce a coarse surface roughness or at an impact angle (α) ≤ 80 °, in particular 45 ° <α <80 °, on the surface (3) of the component (1, 120, 130, 155) meets to produce a fine surface roughness.

2. The method of claim 1, wherein at an angle of incidence (α) ≤ 80 °, a finer surface roughness is generated than with an angle of incidence (α) of 90 °.

3. The method of claim 1, wherein a coarse surface roughness is generated with an angle of incidence (α) of 90 ° than at an angle of incidence (α) <80 °.

4. The method of claim 1, 2 or 3, which is used in HVOF coating.

5. The method of claim 1, 2 or 3, which is used in cold gas spraying.

6. The method of claim 1, 2, 3, 4 or 5, wherein in a turbine blade (120), the airfoil

(406) is coated except for a transition (19) between the blade (406) and / or platform (403) with an angle of incidence (α) of 90 ° + 2 °.

7. The method of claim 1, 2, 3, 4 or 5, wherein a turbine vane (130) is coated, wherein only a portion (22) of the airfoil (406) coated with an angle of incidence (α) of 90 ° + 2 ° is and in which the transitions (19, 19 ') between the airfoil (406) and / or platforms (403, 403') with a

Impact angle (α) ≤ 80 ° are coated.

8. The method according to one or more of the preceding claims, wherein a metallic layer is applied.

9. The method of claim 8 wherein the metallic layer is an outermost layer.

10. The method of claim 8, wherein the metallic layer is applied as an intermediate layer.

11. The method of claim 1, 8, 9 or 10, wherein a layer as an intermediate layer with coarse

Surface roughness and then an outer layer, in particular a ceramic layer, in particular a plasma-sprayed layer, is applied directly to the intermediate layer.

12. The method of claim 1, 8, 9 or 10, wherein a layer as an intermediate layer with fine surface roughness and in which an outer layer, in particular an EB-PVD layer, in particular a ceramic layer is applied directly to the intermediate layer.

13. The method of claim 1, 2, 3, 4, 5, 8 or 9, wherein a component (120, 130, 155) with an angle (α) <

80 ° is coated so that everywhere on the surface to be coated a fine

To achieve surface roughness, which forms the outermost layer.

14. component (120, 130, 155) with a layer, in particular produced according to one or more of the preceding claims 1 to 13, which has locally different surface roughness.

A turbine blade (120, 130) according to claim 14 having a coarse surface roughness layer on the airfoil (406) and at the transition (19, 19 ') between airfoil (406) and blade platform (403, 403') and / or on the blade platform (403, 403 ') opposite the

Surface roughness on the airfoil (406) has a fine surface roughness.

16. Component according to claim 14 or 15, whose layer consists of an MCrAlX alloy.