EP2761057A1

EP2761057A1 - Layer system having a structured substrate surface and process for the production thereof

Info

Publication number: EP2761057A1
Application number: EP12761600.1A
Authority: EP
Inventors: Alessandro Casu; Oliver Lüsebrink
Original assignee: Siemens AG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2011-11-14
Filing date: 2012-09-14
Publication date: 2014-08-06
Anticipated expiration: 2032-09-14
Also published as: WO2013072092A1; US20140302282A1; EP2592174A1; EP2761057B1; US10371004B2

Abstract

As a result of a structured surface of the substrate, this roughness becomes positioned on an interface of the layers located above, and the adhesion of the layers to one another is thereby improved.

Description

Layer system with structured substrate surface and

Process for the preparation

The invention relates to a layer system and a method for the production in which the substrate surface has a greater roughness than an interface between the layers.

Components for high temperature applications must be protected against overheating

Heat input to be protected. This is preferably done by layers, in which an outer ceramic layer is applied to a metallic adhesion promoter layer which has been applied to a metallic substrate.

Depending on the type of application of the ceramic layer, the roughness of the metallic adhesion promoter layer plays a decisive role for the service life of the ceramic thermal barrier coating

Role.

It is therefore an object of the present invention, o. Task to further improve.

The problem is solved by a layer system according to

Claim 1 and a method for producing a

Layer system according to claim 14 or 15.

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

Show it:

Figure 1 is a layer system according to the prior

Technology,

FIGS. 2, 7, 8 show a layer system according to the invention,

FIG. 3 shows a gas turbine,

FIG. 4 shows a turbine blade,

FIG. 5 shows a combustion chamber,

Figure 6 is a list of superalloys. The description and the figures only represent

Embodiments of the invention.

1 shows a layer system 1 'according to the prior art.

On a substrate 4 'is a metallic

Adhesive layer 7 '(MCrAlX) applied, which on its surface 10' to the outer layer, a ceramic thermal barrier coating 13 'has a certain roughness. This results from the known coating methods, in particular by thermal coating methods, in particular by plasma spraying (APS, VPS, LPPS) or by HVOF.

FIG. 1 is a simplified illustration because the application is curved the substrate 4 as with an airfoil 406 (FIG. 4) of a turbine blade 120, 130 (FIG. 4).

The maximum difference between the highest elevation 24 'and the deepest depression 21' of the rough surface 10 'of the layer 7' according to the prior art is r _s . Highest increase 24 'and deepest pit 21' of these max / min values for r _s need not be adjacent.

The maximum distance measured from tip to tip between two directly adjacent elevations 24 'of the rough surface 10' of the layer 7 'is d _s .

The values r _s , d _s are given by the coating, ie by the coating method, parameters, powder, ....

The texture (roughness) of the surface 10 'is irregular and therefore has no periodicity. Same definition applies to the rough surface 16 'of the

Substrate 4 'with r' _s (maximum difference between the highest elevation 24 and the deepest depression 21 of the rough surface 16 'of the substrate 4', analogous to r _s ) and d ' _s (maximum Distance between two peaks of two directly adjacent

Elevations 24 of the substrate 4 '; analogous to d _s ). The values r ' _s and d' s result from the casting or processing,

Smoothing the substrate 4 '.

An average line of elevations 24 'and depressions 21' of the rough surface 10 'would be between the highest elevation 24' and the deepest depression 21 'of the rough surface 10'.

run. The same applies to the surface 16 'of the substrate 4'. The values r _s and r ' _s and d _s and d' _s are not

inevitably the same.

A substrate centerline 30 'of the surface 16' of the

Substrate 4 ', i. a line that is the mean of the

Ridges 24 'and depressions 21' of the rough surface 16 'represent a layer thickness center line 33' of the layer 7 ', i. a line running in the middle of the layer 7 'and a layer surface centerline 36', i. a line representing the average of the ridges 24 and the recesses 21 of the rough surface 10 'of the substrate are straight.

In the real component 120, 130 on the airfoil, they are simply bent 30 ', 33', 36 '(FIG. 7) or run like a surface of a prior art component 120, 130.

On the other hand, the layer system 1 according to the invention according to FIG. 2 has a substrate 4 in which the structure of FIG

Boundary surface 16 of the substrate 4 was selectively and controlled changed and thus also the boundary surface 10 of the layer 7, on which a ceramic coating 13 takes place.

The boundary surface 16 of the substrate 4 has a different structure, ie a higher roughness than the surface 16 '(between substrate 4' and layer 7 ') according to the prior art (FIG. 1).

A valley 23 and a mountain 20 or valleys and mountains make the boundary surface 16 of the substrate 4 rougher, the quasi through Undulation of a substrate 4 'is formed and increase the boundary surface 16 with respect to the surface 16' of the substrate 4 '(Fig. 1). A substrate surface centerline 30 of the boundary surface 16, ie, a line representing the average of ridges 224 and depressions 221, or one

Layer thickness centerline 33 of layer 7 or a

Surface centerline 36 of layer 7 (definition of 30, 33, 36 as in 30 ', 33', 36 ') are not straight but wavy, being undulated at least 5 times (Figure 8),

especially periodically wavy, are. An average line through mountains 20 and valleys 23 would be as well as in the prior art.

The mountain 20 and the valley 23 is still a smaller roughness (R _s = minimum difference of at most increase 224 'of

Layer 7 and deepest depression 221 'of the layer 7), as known from the prior art, superimposed.

The difference between a highest mountain 20 and a deepest valley 23 (in Fig. 2 randomly directly

successively) of the substrate 4 formed by the corrugation of a prior art substrate 4 'is R ⁴ i.

The preferably wave-shaped boundary surface 16 also has the superposed roughness R _s , which, however, is smaller than the specifically set roughness Ri ^{4 of} the substrate 4.

The maximum distance from adjacent mountain 20 and valley 23 of the substrate 4 is D 'i. Analogously, this applies to the surface 10 of the layer 7 with Di.

D 'i (maximum distance mountain 20' and valley 23 'of layer 7) is comparable to Di.

The value d 'i, ie the maximum distance between two peaks of adjacent ridges 224 of the wavy rough surface 16 ', here then boundary surface 16, is comparable to d' _s .

Accordingly defined is R ⁷ i. The value R ⁷ i is comparable to the value R ⁴ i, since the metallic layer 7 is not the mountains 20 and valleys 23 of the surface 16 of the substrate 4

compensates

Likewise, the value R ' _s , ie the maximum difference between highest increase 224 and deepest depression 221 of the corrugated rough surface 16', in this case the

Boundary surface 16, comparable to r ' _s .

The rough surface 10 'of a layer 7' (FIG. 1) therefore quasi additionally only corrugated to the adhesion promoter layer 7 and therefore has comparable values d _s (FIG. 1) for d ± (= maximum distance between two adjacent elevations 224 ') ,

The value R _s , ie the maximum difference between the highest elevation 224 'and the deepest depression 221' of the layer 7, for the interface 10 is comparable to the value r _s of the prior art (FIG. 1) for the same coating technique and powder. ,

To determine the roughness, the square or average roughness (Rq or Ra) can also be used.

Preferably, the roughness of the surface 16 of the substrate 4 is at least 20%, in particular 30% rougher than the interface 10 'between the layers 7', 13 'according to the prior art (FIG. 1), ie the value R ⁷ i or R ⁴ i is at least 20%, in particular 30% greater than value r _s or r ' _s .

The roughness with the valley 23 and the top 20 of the substrate 4 is preferably uniform at least in places, that is, for example, sinusoidal or has at least one constant wavelength (waviness) or constant

Distances between directly adjacent mountains. The unprocessed surface 16 'has no particular

Uniformity or periodicity.

Preferably, the waviness of the boundary surface 16 of the substrate 4 is greater than that of the surface 10 'according to the prior art, ie at least 20%, ie, the distances between two "mountains" 20 are greater The smallest distance Di (FIG. neighboring mountains 20 is at least 20%, in particular 30% larger than the largest distance d ± (or d _s ) of adjacent elevations for the boundary surface 10th

The waviness of the boundary surface 16 of the substrate 4 is also continued through the coating 7 on the boundary surface 10 with the mountain 20 'of the layer 7 and valley 23 of the layer 7.

Due to the superimposition of the higher roughness or waviness of the boundary surface 16 of the substrate 4 and the roughness of the internal, in particular metallic

Adhesive layer 7, the adhesion, the

Overlying layer 13 continues to improve.

The substrate 4 may be structured over the entire boundary surface 16 or only locally.

For a turbine blade 120, 130 this would be

Airfoil 406.

The substrate 4 preferably has a cobalt or

nickel-based alloy, in particular from FIG. 6. The substrate 4 can already have the desired structure on the boundary surface 16 after casting by means of a correspondingly shaped casting mold or it can be cast after casting

machined, in particular by laser processing, to set the desired surface structure.

FIG. 3 shows by way of example a gas turbine 100 in a longitudinal partial section. The gas turbine 100 has a rotatably mounted about a rotational axis 102 ^¬ rotor 103 having a shaft 101, which is also referred to as the turbine rotor.

Along the rotor 103 successively follow an intake housing 104, a compressor 105, for example, a torus-like

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 105 ^¬ be compressed air provided at the turbine end of the compressor is ge ^¬ leads 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. 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).

As a material for the components, in particular for the ^turbine blade or vane 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.

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 , Scandium (Sc) and / or at least one element of the rare earth 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.

On the MCrAlX may still be present a thermal barrier coating, and consists for example of Zr02, Y203-Zr02, ie it is not, partially or completely stabilized by Ytt ^¬ riumoxid 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.

The guide blade 130 has a guide blade foot facing the inner housing 138 of the turbine 108 (not shown here). ) and a vane head opposite the vane root. The vane head faces the rotor 103 and fixed to a mounting ring 140 of the stator 143.

4 shows a perspective view of a rotor blade 120 or guide vane show ^¬ 130 of a turbomachine, which extends along a longitudinal axis of the 121st

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 a blade 406 and a blade tip 415.

As a guide vane 130, the vane 130 may be pointed on its shovel 415 have 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 out staltet ^¬. Other designs as Christmas tree or Schwalbenschwanzfuß are possible.

The blade 120, 130 has a medium felblatt to the Schau- 406 flows past, a leading edge 409 and a ^trailing edge 412th

In conventional blades 120, 130, in all regions 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.

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 takes place e.g. 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 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 avoid solidification transition to globular (polycrystalline), since non-directional growth inevitably forms transverse and longitudinal grain boundaries ^¬ which make the good properties of the directionally solidified or single-crystal component naught.

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. B. (MCrAlX, 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.

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. Besides these cobalt-based protective coatings, nickel-based protective layers such as Ni-10Cr-12Al-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 , Y2Ü3-Zr02, ie it is not, partially ^¬ or fully stabilized by yttria

and / or calcium oxide and / or magnesium oxide.

The thermal barrier coating covers the entire MCrAlX layer.

Other coating methods are conceivable, for example atmospheric plasma spraying (APS), LPPS, VPS or CVD. The heat insulation layer may have ^¬ porous, micro- or macro-cracked ^compatible grains for better thermal shock resistance. The Thermal insulation layer 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 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 also has, if necessary, film cooling holes 418 ^(indicated by dashed lines) on.

FIG. 5 shows a combustion chamber 110 of a gas turbine.

The combustion chamber 110 is configured, for example, as so-called ^an annular ^combustion chamber, in which a plurality of in the circumferential direction about an axis of rotation 102 arranged burners 107 open into a common combustion chamber space 154 and generate flames 156th 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. To even with these operating parameters unfavorable for the materials, a comparatively long operating time to be made ^¬ union, the combustion chamber wall 153 is provided on its side facing the ^working medium M facing side with a formed from heat shield elements 155. liner.

Each heat shield element 155 made of an alloy is on the working medium side with a particularly heat-resistant protective layer (MCrAlX layer and / or ceramic coating). equipped or is made of high temperature resistant material (solid ceramic stones).

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.

On the MCrAlX, for example, a ceramic Wär ^¬ medämmschicht be present and consists for example of ZrÜ2, Y203 ^~ Zr02, ie it is not, partially or completely stabilized by yttrium and / or calcium oxide and / or magnesium oxide.

Other coating methods are conceivable, for example atmospheric plasma spraying (APS), LPPS, VPS or CVD. The heat insulation layer may have ^¬ porous, micro- or macro-cracked ^compatible grains for better thermal shock resistance. Reprocessing (Refurbishment) means that ^heat shield elements may need to be removed 155 after use of 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.

Thereafter, a re-coating 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 hollow and have, for example possibly still in the combustion chamber 154 opening cooling holes (not shown).

Claims

claims

1st layer system (1),

which has at least two layers (7, 13),

an inner layer (7) on the boundary surface (16) of a substrate (4),

especially directly on the boundary surface (16),

wherein the inner layer (7) has a certain roughness (Rs) in the region of the surface (10) to the outer layer (13),

due to the known coating methods,

characterized in particular by thermal coating processes, in particular by plasma spraying and / or by HVOF, characterized in that the roughness (R ⁴ i) of the boundary surface (16) of

Substrate (4) is set specifically

or

is processed after its production, in particular after casting,

in particular is increased.

2. Layer system according to claim 1,

in which a layer thickness center line (33) of the layer (7) is bent several times,

in particular at least 5 times,

In particular, at least in places, periodically bent.

3. Layer system according to one or both of claims 1 or 2,

wherein the substrate (4) on its boundary surface (16) at least in places, in particular completely one Has periodicity.

4th layer system according to one or more of

preceding claims 1, 2 or 3,

wherein the boundary surface (16) of the substrate (4) with

Mountains (20) and valleys (23) a ripple with a

Has periodicity and

the surface (10) has no periodicity,

if mountains (20) and valleys (23) were not present.

5. Layer system according to claim 3,

in which the periodicity of the waviness of the boundary surface (16) with mountain (20) and valley (23) is at least 20%,

In particular, 30% greater than the periodicity of

Surface (10) of the layer (7),

if mountains (20) and valleys (23) were not present.

6. Layer system according to one or more of

previous claims,

where the roughness is the mean roughness (Ra).

7. Layer system according to one or more of

previous claims,

where the roughness is the square roughness (Rq).

8. Layer system according to one or more of

previous claims,

in which the roughness (R ⁴ i) of the boundary surface (16) of the substrate (4) with mountains (20) and valleys (23) is at least 20%, in particular at least 30% greater than the roughness (R _s ) of the boundary surface (16 )

if mountains (20) and valleys (23) were not present.

9. Layer system according to one or more of the preceding claims,

wherein the difference (R ⁷ i) between highest mountain (20 ') and lowest valley (23') of the layer (7) compared to the maximum difference (R _s ) between highest increase

(224 ') of an inner layer (7) and deepest valley (221') of the inner layer (7) is at least 20%, in particular 30%,

if mountains (20) and valleys (23) were not present.

10. Layer system according to one or more of the preceding claims,

in which the maximum distance between two adjacent elevations (224 ') of the boundary surface (10) to the outer

Layer (13) d ± is,

in which the smallest distance between two peaks (20 ') of a boundary surface (10) of the layer (7) is Di and in which Di is at least 20%, in particular 30% greater than d ±.

11. Layer system according to one or more of the preceding claims,

where the maximum distance between two adjacent ones

Elevation (224) and deepest depression (221) is where the smallest difference between the peak (20) and valley (23) of the machined boundary surface (16) of the substrate (4) is D'i and

where D'i is at least 20%, in particular 30% larger than d'i.

12. Layer system according to one or more of the preceding claims,

in which the inner layer (7) is a metallic adhesive layer,

on which an outer ceramic layer (13) is applied.

13. Layer system according to one or more of

previous claims,

wherein the substrate (4) has only a larger roughness or a periodicity locally,

in particular with a turbine blade (120, 130) the blade (406) at least partially,

completely in particular completely.

14. Layer system according to one or more of the preceding claims,

wherein the substrate (4) is metallic.

15. A method for producing a layer system according to one or more of the preceding claims 1 to 14, wherein a structure in the boundary surface (16) of the substrate (4) is produced by a laser processing.

16. A method for producing a layer system according to one or more of the preceding claims 1 to 14,

in which the substrate (4) already has a structured boundary surface (16) by casting,

which results in a waviness in the boundary surface (10) of the layer (7).