EP3033439A1 - Two-ply ceramic layer with different microstructures - Google Patents

Abstract

The invention relates to the use of a two-ply heat-insulating ceramic layer with a highly porous crack-free lower ply and an outermost heat-insulating ply with vertical cracks in order to ensure both a high heat insulation as well as a high erosion resistance.

Description

Two-layer ceramic layer with different ^{microstructures}

The invention relates to a ceramic layer, the one

Has two layers, wherein in the layers different microstructures are present.

Ceramic layers are used, in particular in turbine showers, as heat-insulating layers and have a porosity.

Also known are vertically segmented thermal barrier coatings in which cracks during coating result from subsequent treatment.

However, there is the problem that increasing the Porosi ^¬ ity to achieve a higher thermal insulation, the erosion resistance of a thermal barrier coating, which is usually plasma-sprayed, is reduced.

It is therefore an object of the invention to solve the above-mentioned problem. The object is achieved by a thermal barrier coating system according to claim 1.

The subclaims list further advantageous measures which can be combined with one another as desired in order to achieve further advantages.

The advantages are good thermal insulation and good erosion resistance. Show it:

FIGS. 1 to 4 embodiments of the invention,

Figure 5 is a list of superalloys and

FIG. 6 shows a turbine blade.

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

In Figure 1 and in Figures 2 to 4 are each a

Layer system 1 ^λ , 1 ^{λ λ} , ..., which has at least one me ^¬ tallisches substrate 4.

 The metallic substrate 4 has in particular a cobalt- or nickel-based superalloy, in particular according to FIG.

On the substrate 4 (Fig. 1 - 4) comprises a metal ^¬ metallic bonding layer 7 is preferably applied, more in particular directly on the substrate 4.

 This metallic adhesion promoter layer 7 preferably comprises an alloy of the type NiCoCrAl (X), on the surface of which a protective aluminum oxide layer forms during the further coating or in operation (TGO) (not shown).

On the substrate 4 or the metallic adhesion promoter layer 7, a lower ceramic layer 10 ^λ (FIG. 1) of a two-layer, outermost ceramic thermal barrier coating 15 ^{λ is} applied.

The porosity is preferably given in vol%.

Thereby an APS process is preferably used for the bottom ceramic layer 10 ^λ of Figure 1 and the lower ke ^¬ ramische layer 10 ^λ of the two-layer outermost ceramic thermal barrier coating 15 has a porosity of ^λ (12 +/- 4%) to. The lower ceramic layer 10 ^λ preferably has a layer thickness of up to 1 mm.

The minimum thickness of the lower ceramic layer 10 ^λ is at least 100 μm, very particularly at least 150 μm (FIGS. 1-4).

The outermost ceramic layer 13 comprises in the figures 1 to 4, in comparison to the lower layer 10 10 ^IV of the two-layer ceramic thermal barrier coatings 15 15 ^{λ λ,} ... dense layer, which is vertically penetrated with cracks, that is, the porosity is preferably at <8%.

 The minimum layer thickness of the outermost ceramic layer 13 is 30ym, in particular at least 50ym (FIGS. 1-4).

The maximum layer thickness of the outermost ceramic layer 13 is a maximum of 500 μm, in particular a maximum of 300 μm (FIGS. 1 to 4).

The porosity of the segmented layers, such as here the outermost ceramic layer 13 corresponds to that of the prior art.

FIG. 2 shows a further exemplary embodiment with a layer system 1 ^{λ λ} .

In contrast to Figure 1, the lower layer 10 ^{λ λ} of kera ^¬ thermal thermal barrier coating 15 ^{λ λ has} a porosity of (15 +/- 4)%.

Also preferably, the lower ceramic layer 10 ^{λ λ} in Figure 2 have a layer thickness of up to 1.5mm, in particular> lmm to 1.5mm and then have a porosity of (20 +/- 5)%.

 The minimum layer thickness of the outermost ceramic layer 13 is 30ym, in particular at least 50ym.

Also preferably, the porosity of the lower ceramic layer 10 ^{λ λ} in Figure 2 can be further increased to (25 +/- 5)% and preferably layer thicknesses> 1.5mm are produced. The minimum layer thickness of the outermost ceramic layer 13 is 30ym, in particular at least 50ym.

Figure 3 shows a further embodiment of a layer system in accordance OF INVENTION ^¬ dung 1 ^{λ λ λ.}

The lower ceramic layer 10 ^{λ λ λ of} the thermal barrier coating 15 ^{λ λ λ} has a porosity of preferably greater than 15% and was prepared by an APS process. The pores are sorted ^¬ but has preferably been produced by spraying a ceramic powder by means of polymers.

This results in a characteristic microstructure of the pores. The lower ceramic layer 10 ^{λ λ λ} may preferably be a

Have layer thickness of several millimeters, in particular> 2mm.

 The minimum layer thickness of the outermost ceramic layer 13 is 30ym, in particular at least 50ym.

FIG. 4 shows a further layer system 1 ^IV according to the invention.

The lower ceramic layer 10 ^{IV of} the two-layer, ceramic thermal insulation layer 15 ^IV is produced by the suspension plasma spraying process (SPS) and has a ductile stalk structure with a certain porosity of 4% and with cracks of up to <8%. , The outermost layer 13 in Figure 4 is formed according to the Min ^¬ least layer thickness and structure and maximum layer thickness in FIGS. 13

Yttrium oxide, partially stabilized zirconium oxide or heat-insulating layers of fully stabilized zirconium oxide are suitable as materials for the outermost, ceramic thermal insulation layers 15... 15 ^IV . It is also possible pyrochlore as gadolinium, gadolinium, lanthanum, Gadolinumzirkonat turn to ver ^¬.

In this case, 10 10 ^{λ λ,} ..., and the outermost layer can be varied 13, the materials for the lower ceramic layer depending on conditions of use and Herstellungsmög- possibilities.

The two-layer outermost ceramic layer 15 is preferential ^¬ as the outermost layer of the layer system 1 ^λ 1 ^{λ λ,} ....

6 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 hereby be produced 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, it is necessary to avoid starrung transition to globular (polycrystalline) Er, since non-directional growth inevitably forms transverse and longitudinal grain boundaries ^¬ which solidified the directionally or negate the good properties of single-crystal component.

If the term generally refers to directionally solidified microstructures, it refers both to single crystals which have no grain boundaries or at most small-angle grain boundaries, and also to columnar crystal structures which are probably longitudinally extending grain boundaries but no transverse grain boundaries. have 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.

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 consisting of iron (Fe), cobalt (Co), Ni ^¬ ckel (Ni), X is an active element and stands for yttrium (Y) and / or silicon and / or at least one element the rare 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 log ^¬ te.

 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-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.

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, for example atmospheric plasma spraying (APS), LPPS, VPS or CVD. The heat- insulating layer may have porous, micro- or macro-cracked Kör ^¬ ner 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 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 How derbeschichtung of the component 120, 130 and a renewed use of the component 120, 130th

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.

Claims

Patent claims 1. Layer system (1\ 1 ^λ \ 1 ^{λ λ} \ l ^iV ) with a two-layer, outermost ceramic layer (15 15 *\ ...), which has a lower ceramic layer (10 10 ^{λ λ} , ...) and an outermost ceramic layer (13), where the lower ceramic layer (10 10 ^{λ λ} , ...) has a porosity of at least 5%, in particular of at least 8%, especially at least 10%, has and little or no vertical cracks, in particular no continuous vertical cracks, having, wherein the outermost ceramic layer (13) has a layer ^thickness of at most 40%, in particular of a maximum of 20%, in particular of at most 10% of the layer thickness of the lower ceramic layer (10 ^λ , 10 ^{λ λ} , ...). 2. Layer system according to claim 1, in which the outermost ceramic layer (13) has a minimum layer thickness of 30ym, especially from 40ym, especially from 50ym, having . Layer system according to one or both of claims 1 or 2, in which the outermost ceramic layer (13) has a maximum layer thickness of 500ym, in particular 300ym. 4. Layer system according to one or more of claims 1, 2 or 3, in which the lower ceramic layer (10 ^λ ) of the two-layer ceramic layer (15 ^λ ) has a porosity of (12 +/- 4)% and in particular has a layer thickness of up to 1mm. 5. Layer system according to one or more of the previous claims 1 to 3, in which the lower ceramic layer (10 ^{λ λ} ) of the two- ^layer ceramic layer (15 ^{λ λ} ) has a porosity of (15 +/- 4) % has and in particular has a layer thickness of up to 1mm. 6. Layer system according to one or more of the previous claims 1 to 3, in which the lower ceramic layer (10 ^{λ λ} ) of the two- ^layer ceramic layer (15 ^{λ λ} ) has a porosity of (20 +/- 5) % and in particular a layer thickness of up to 1.5mm, in particular from > 1mm to 1.5mm. 7. Layer system according to one or more of claims 1 to 3, in which the lower ceramic layer (10 ^{λ λ} ) of the ^ceramic layer (15 ^{λ λ} ) ^has a porosity of (25 +/- 5)% and in particular has a layer thickness of > 1.5mm. 8. Layer system according to one or more of claims 1 to 3, in which the lower ceramic layer (10 ^{λ λ λ} ) has a ^porosity of >15%. 9. Layer system according to one or more of claims 1 to 3, in which the lower ceramic layer (10 ^IV ) of the thermal insulation ^layer (15 ^IV ) has a ductile stem structure. 10. Layer system according to one or more of the previous claims, in which the lower ceramic layer (10 ...) of the two-layer ceramic thermal insulation layer (15 ...) is covered by an APS Process was produced. 11. Layer system according to one or more of the previous claims, in which the lower ceramic layer (10 10 ^{λ λ} , 10 ^{λ λ λ} ) of the two-layer ceramic thermal insulation layer (15 15 ^{λ λ} , 15 ^{λ λ λ} ) was produced by spraying ceramic powders with polymers. 12. Layer system according to one or more of the previous claims 1 to 9, in which the lower ceramic layer (10 ^IV ) of the two-layer ceramic thermal insulation layer (15 ^IV ) by suspension Plasma spraying (SPS) was produced. 13. Layer system according to one or more of the previous claims, in which the materials for the lower ceramic layer (10 10 ^{λ λ} , ...) and the outermost ceramic layer (13) are selected from: zirconium oxide, partially stabilized or fully stabilized, and / or pyrochlores. 14. Layer system according to one or more of the previous claims, in which the two-layer ceramic layer (15 15 ^{λ λ} , ...) which represents the outermost layer. 15. Layer system according to one or more of the previous claims, in which the lower ceramic layer (10 \ 10 ^λ \ ...) has a minimum thickness of at least lOOym, especially from 150ym, having . 16. Layer system according to one or more of the previous claims, in which the outermost ceramic layer (13) is tightly ^formed , in particular has a porosity kle. 17. Layer system according to one or more of the previous claims, in which the outermost ceramic layer (13) is vertically riddled with cracks.