EP1931811A1

EP1931811A1 - Dry composition, use of its layer system and coating process

Info

Publication number: EP1931811A1
Application number: EP06806827A
Authority: EP
Inventors: Roman Karmazin; Steffen Walter
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2005-10-07
Filing date: 2006-09-26
Publication date: 2008-06-18
Also published as: WO2007042392A1; US20090263579A1; EP1772529A1; US7998600B2

Abstract

Coating processes are often only intended to be applied locally. At the same time, local coating processes cannot always be used, so that frequently masking has to be used. The protective layer (7) according to the invention contains a binder and titanium oxide and can be used according to the invention as a diffusion barrier, so that, in a coating process, the coating material is only applied locally. The binder is converted into carbon before the coating.

Description

Dry composition, use of those, layer system and

Method of coating

The invention relates to a dry composition, a use thereof, a layer system and a method for coating.

In many coating processes, often only a local coating is required. This can be the case with all common coating methods, such. For example, in plasma spraying (atmospheric plasma spraying APS, LPPS low-pressure plasma spraying, VPS ...) or PVD and CVD method. Even with the so-called packing method in which the component to be coated is introduced into a powder bed, it is sometimes required that only a local coating should take place.

Similarly, a mask is sometimes required if a Be ^¬ coating process that allows a local coating without any further aids, is used. This is z. B. at

Schlickerverfahren the case, wherein the slurry is applied locally and by heating the slurry, the coating material only locally applied or applied, but a cloud of steam of the coating material can be reflected on other areas of the component.

It is therefore an object of the invention to show a composition for a protective layer as a mask, which can be easily used.

The object is achieved by a dry composition according to claim 1 and by a use of those according to claim 5. In addition, it is an object of the invention to provide a layer system that made a topical coating of a component ^¬ light and can be easily removed in which a protective layer as a mask. The object is achieved by a layer system according to ^¬ demanding. 6

In addition, it is an object of the invention to show a coating method in which a local coating of a component can be produced and in which the masking can be easily removed.

The object is achieved by a method according to claim 11.

The measures listed in the dependent claims can be combined with each other in an advantageous manner.

1, 2 schematically show a component with a large-area masking,

3, 4 schematically a component with local masking and a method for coating, FIG. 5, 6 further exemplary embodiments of the invention, FIG. 7 a perspective view of a gas turbine, FIG. 8 a perspective view of a combustion chamber,

Figure 9 is a perspective view of a turbine blade.

Figure 1 shows a component 1, be a substrate 4 ^¬ is, is applied to the protective layer. 7

The component 1 can be a turbine blade 120, 130 (FIG. 9), a housing 138 (FIG. 7) or a combustion chamber element 155 (FIG. 8) of a steam or gas turbine 100 (FIG be any component which is coated by a known coating method.

The substrate 4 has an outer surface 10 and an inner surface 13, wherein the outer surface 10 is not to be coated in a coating process, so that the outer surface 10 is the non-coating area 11. Therefore, the protective layer 7 is applied on the entire surface 11.

The protective layer 7 comprises a dry composition according to the invention consisting of carbon (C) and nickel (Ni) powder. The carbon may be in chemically bonded form with other chemical elements, especially as an organic binder, which converts to carbon upon heat treatment (curing).

The carbon of the dry composition may be present at least partially, in particular completely in chemically bound form.

Also, the carbon of the dry composition may be at least partially or completely of a det ^¬ carbon powder, such as graphite powder or carbon black gebil-.

Preferably, the carbon of the dry composition ^¬ reduction of carbon in powder form and a binder which is converted to a heat treatment process in carbon.

The dry composition can be applied to the surface 11 of a component 1, 120, 130, 138, 155 in the form of a paste or a slurry. The protective layer 7 can be applied to each surface 10 or 13 of the component 1, 120, 130 and is preferably applied as a slurry over a large area, but also locally limited to the component 1, 120, 130, 138, 155.

The binder is either so soft (viscous) that it can be applied as a paste or a solvent (for example water, alcohol) is added to the dry composition which lowers the viscosity sufficiently. Preferably, the binder is mixed with novolac. The

Base resin Novolak is a polymer product of phenol and / or cresol and formaldehyde, which is formed by polycondensation reaction. The number of chain segments n is about 1000 to 2000. Novolac is a very brittle material, its softening point is about 100 ⁰ C.

Another non-carbonaceous binder or other carbonaceous binder can be added to the dry composition, paste, or slurry.

Before coating, the binder and / or the carrier can be expelled and preferably the nickel carbon ^¬ powder be sintered.

The protective layer 7 is preferably suitable for gas-phase coating processes such as. As the PVD or CVD method in which a cloud of vapor is deposited from a material on a Oberflä ^¬ che. In this case, a masking is formed by the protective layer 7, which acts as a diffusion barrier by the nickel reacts with the gaseous coating material.

During the aluminization of a component 1, the nickel reacts to nickel aluminum (eg Al ₃ Ni), whereby the protective effect of the protective layer 7 continues to increase. The coating material can not layer by this protection ^¬ penetrate 7th The resulting protective layer 7 is often very brittle and can by a simple decoating method such. B. dry ice blasting are removed.

Likewise, such a protective layer 7 can be used in a chromation.

Preferably, the Ni / C composition is used in nickel-based materials, as here a diffusion of nickel of the substrate 4 in the masking or a reaction of

Nickel of the substrate 4 with the nickel-containing protective layer 7 is reduced or even prevented, since a concentration ^¬ gradient is present, which counteracts. The particular higher nickel content in the protective layer 7 during the coating process forms a nickel concentration gradient. This prevents the Dif ^¬ fusion of nickel from the base material in the oberflächenna ^¬ hen layers. The higher nickel concentration in the protective layer 7 on the surface 11 of the substrate 4 counteracts the nickel diffusion in the substrate 4 and prevents its segregation.

In an alitizing a nickel-based alloy with a protective layer without nickel arises sion by Nickeldiffu- is formed deeper in the substrate, a 40 microns wide Entmi ^¬ research layer to having chromium and aluminum-rich areas, in which case lower is present in the substrate 4, the substrate 4 in the initial state. After the component 1, 120, 130 was in use, the area of the demixing layer is also removed. This is na ^¬ not Türlich wanted.

By using the dry composition with nickel and carbon, it is possible to prevent both the diffusion of aluminum during a coating process and the formation of the demixing layer. FIG. 2 shows a further protective layer 7 'according to the invention. The protective layer 7 'is constructed in two layers, wherein the protective layer 7 has ben as in Figure 1 beschrie ^¬ the composition. However, below the protective layer 7 there is a further layer 8, which in particular rests directly on the substrate 4. The protective layer 8 is a carbons ^{¬-containing} layer, which either only of carbon or Kohlenstoffprecursormaterialien such. B. organic materials. Preferably, the layer 8 consists of carbon powder and a binder, which in turn advantageously novolak is used.

This carbon-containing layer allows the lighter Ent ^¬ fernung the protective layer 7, after the component 1, 120, 130, 155 was coated, as the carbon layer 8 does not react with the substrate 4 and not material comes with the coating in contact.

Preferably, this two-ply layer system 7 'is used in an alitization.

Figure 3 schematically shows a process sequence of OF INVENTION ^¬ to the invention coating process. The substrate 4 is not to be coated in a region 11, so that locally a paste or a slip on the

Surface 10 is applied in the region of the not to be coated Oberflä ^¬ che 11 to form a protective layer 7. Then, the component 1, 120, 130, 155 driving the coating processes is subjected, for example, an aluminum vapor, then an aluminum layer 16 det bil ^¬ on the surface 10, except for the area where the protective layer 7 EXISTING ^¬ is.

After removal of the aluminum-enriched protective layer 7 or of the reaction products of protective layer 7 and coating material, in this case aluminum, a local coating has formed (FIG. 3 on the far right). FIG. 4 shows a comparable and schematic process sequence as in FIG. 3, with the difference that no layer 16 is formed on the surface 10 here, but rather that the coating material, here likewise, for example, aluminum, locally penetrates into the substrate 4, so that local regions are formed 19 with an increased aluminum content ausbil ^¬ the.

Figure 5 shows a further embodiment of the method according OF INVENTION ^¬ dung and a further use of the protective layer. 7

The component 1, 120, 130, 155 has a cavity 22 which is to be coated entirely or locally alone. This is the game as if the outer surface of the sub ^¬ strats 4 already an MCrAlX layer and optionally bearing a ceramic layer at ^¬ the case, but the cavity 22 is also aluminized onsschutzzwecken to corrosion or is to be chromed.

Then, a paste or slurry for forming a protective layer 7 is applied to the outer surface 10 of the substrate 4 or an outer coating on the substrate 4 so that no coating material can reach the outer surface 11 and only one coating takes place in the cavity 22 ,

Likewise, it may be possible for the outer surface of a hollow component 1, 120, 130 to be coated, for example an MCrAlX layer or a substrate 4 should be aluminised or chromed for corrosion protection purposes, but the cavity 22 should not be coated , Here, a paste or a slurry is also for the generation ^¬ supply a protective layer 7 in the cavity 22 is introduced, the cavity 22 prior to coating protects (Figure 6). FIG. 7 shows by way of example a gas turbine 100 in a longitudinal partial section.

The gas turbine 100 has an axis by a rotational ^¬ 102 rotatably mounted rotor 103 having a shaft 101, which is also referred to as the turbine rotor.

Along the rotor 103 follow one another an intake housing 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 . As seen in the direction of flow of a working medium 113, in the hot gas channel 111 of a row of guide vanes 115, a series 125 formed of rotor blades 120 follows.

The guide vanes 130 are fastened to an inner housing 138 of a stator 143, whereas the moving 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 100 104 air 135 is sucked by the compressor 105 through the intake housing and ver ^¬ seals. The loading 105 compressed air provided at the turbine end of the compressor to the burners leads 107 ge ^¬ 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. On the rotor blades 120, the working medium 113 expands in a pulse-transmitting manner, so that the rotor blades 120 drive the rotor 103 and drive the machine coupled to it. The components exposed to the hot working medium 113 are subject to thermal loads during operation of the gas turbine 100. The guide vanes 130 and rotor blades 120 of the first turbine stage 112, viewed in the flow direction 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. To withstand the prevailing temperatures, 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 longitudinal grains (DS structure). Iron, nickel or cobalt-based superalloys are used as material for the components, in particular for the turbine blades 120, 130 and components of the combustion chamber 110.

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.

Also, the blades 120, 130 may be anti-corrosion coatings (MCrAlX; M is at least one element of the group iron (Fe), cobalt (Co), nickel (Ni), X is an active element and is yttrium (Y) and / or silicon and / or at least one element of the rare earths or hafnium). 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 are to be part of this disclosure with regard to the chemical composition.

On the MCrAlX may still be present a thermal barrier coating, and consists for example of ZrO ₂ , Y ₂ O ₃ -ZrO ₂ , ie it is not, partially or completely stabilized by yttrium oxide and / or calcium oxide and / or magnesium oxide.

Suitable coating processes, such as electron beam evaporation (EB-PVD), produce stalk-shaped grains in the thermal barrier coating. The guide vane 130 has an inner housing 138 of the turbine 108 facing guide vane root (not provide Darge ^¬ here) and a side opposite the guide-blade root vane root. The vane head faces the rotor 103 and fixed to a mounting ring 140 of the stator 143.

8 shows a combustion chamber 110 of a gas turbine 100. The combustion chamber 110 is designed for example as so-called ^an annular ^combustion chamber, in the circumferential direction in which a plurality of an axis of rotation 102 of burners 107 arranged in a common combustion chamber space 154, the flames 156 generate. 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. A relatively long service life even with these handy, unfavorable for the materials to operational parameters made ^¬, the combustion chamber wall 153 is provided on its side facing the medium M, Arbeitsme- facing side with a formed from heat shield elements 155. liner.

Each heat shield element 155 made of an alloy is equipped on the working fluid 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 can 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 Bl, EP 0 412 397 B1 or EP 1 306 454 Al, which should be part of this disclosure with respect to the chemical composition of the alloy.

On the MCrAlX, for example, a ceramic thermal insulation layer may be present and consists for example of ZrO ₂ , Y ₂ O ₄ -ZrO ₂ , ie it is not, partially or fully ^¬ dig stabilized by yttrium and / or calcium oxide and / or magnesium oxide.

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

Reprocessing (Refurbishment) means that ^heat shield elements must be freed 155 after use, where appropriate, protective layers (for example 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 inside the combustion chamber 110 may also be provided for the heat shield elements 155 and for their holding elements, a cooling system. The heat shield elements 155 are then, for example, hollow and possibly still have film cooling holes (not shown) which open into the combustion chamber space 154.

FIG. 9 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 to each other, a securing region 400, an adjoining blade or vane platform 403 and an airfoil 406. As a guide vane 130, the vane 130 may have tip at its ^vane 415 a further platform (not Darge ^¬ asserted).

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, for example, as a hammerhead staltet out ^¬. Other designs as Christmas tree or Schwalbenschwanzfuß are possible. The blade 120, 130 has a medium which flows past felblatt 406 at the spectacle ^¬ a leading edge 409 and a ^trailing edge on the 412th

In conventional blades 120, 130, in all areas 400, 403, 406 of the blade 120, 130, for example, ^massive metallic materials, in particular 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 alloy. The blade 120, 130 can hereby be manufactured 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, ie grains that run the entire length of the workpiece and here, in common parlance, referred to as directionally solidified) or a monocrystalline structure, ie the whole workpiece be ^¬ is made of a single crystal. In these methods, you have to transition to globular (polycrystalline) solidification avoided, since non-directional growth inevitably forms transverse and longitudinal grain boundaries ^¬ which the good properties of the directionally solidified or single-crystal component nullify. 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 that are probably longitudinal but no transverse grain boundaries. In these second-mentioned crystalline

Structures are also known as directionally rigidified structures

(directionally solidified structures).

Such methods are known from US Pat. No. 6,024,792 and EP

0 892 090 Al known; These writings are part of the revelation.

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 and a renewed use of the component 120, 130.

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

Claims

claims

1. Dry composition consisting of carbon (C) and nickel (Ni) powder.

2. Dry composition according to claim 1, in which the carbon is present at least partially, in particular completely, in chemically bound form with other chemical elements, in particular as organic binder, which is convertible to carbon by a heat treatment.

3. Dry composition according to claim 1, wherein the carbon of the dry composition is at least partially, in particular completely, in powder form.

A dry composition according to claim 1, 2 or 3, wherein the carbon of the dry composition is in chemically bonded form and in powder form.

5. Use of the dry composition according to claim 1, 2, 3 or 4 in the form of a paste or a slip, in particular for forming a protective layer (7, 7 ') in a coating process of a component (1, 120, 130, 138, 155) ,

6. layer system comprising a substrate (4) for a component (1, 120, 130, 138, 155) and a protective layer (7, 1 '),

characterized in that

the protective layer (7, 7 ') containing a dry composition according to claim 1, 2, 3 or 4.

7. Layer system according to claim 6, characterized in that

the protective layer (7 ') has at least two layers, wherein on the substrate (4) a carbon-containing layer (8) is present, on which an outer layer (7) containing a dry composition according to claim 1,

2, 3 or 4, is present.

8. Layer system according to claim 7, characterized in that

is formed, the carbon-containing layer (8) powder through a carbon ^¬ and / or chemically bonded carbon, in particular an organic binder.

9. Layer system according to claim 6 or 7, characterized in that

the substrate (4) is a nickel-based alloy

10. Layer system according to claim 9, characterized in that

the nickel content in the protective layer (7 ', 7) is at least equal, in particular higher, than the nickel content in the substrate (4).

11. A method of coating, wherein first the dry composition according to claim 1, 2, 3 or 4 as a paste or slip on at least one non-coated area (11) of a substrate (4) of a component (1, 120, 130, 138, 155) is applied and in a further step of the method, the component (1, 120, 130, 138, 155) having a protective layer (7,7 ') is coated.

12. The method according to claim 11, characterized in that

it takes place via a gas phase.

13. The method according to claim 11 or 12, characterized in that

it represents an aluminization.

14. The method according to claim 11, characterized in that

the paste or slurry is applied by spraying or brushing onto the non-coated area (11).

15. The method according to claim 11, 12, 13 or 14, characterized in that

after the coating process, the reaction product of dry composition and coating material, in particular by dry ice blasting, is removed.

16. The method according to claim 11, characterized in that

as the substrate (4) of the component (1, 120, 130, 138, 155) a nickel-based material is used.

17. The method according to claim 16, characterized in that

the nickel content in the protective layer (7 ', 7) from the tro ^¬ ckenen composition according to claim 1, 2, 3 or 4 At the very least equal to, preferably higher, than the nickel content in the substrate (4).