EP3592953A1

EP3592953A1 - Sealing system for a rotor blade and housing

Info

Publication number: EP3592953A1
Application number: EP18716910.7A
Authority: EP
Inventors: Francis Ladru; Thorsten Schulz
Original assignee: Siemens AG
Current assignee: Siemens Energy Global GmbH and Co KG
Priority date: 2017-04-28
Filing date: 2018-03-21
Publication date: 2020-01-15
Also published as: US20200123911A1; US11274560B2; DE102017207238A1; CN110573696A; CN110573696B; WO2018197114A1

Abstract

The invention relates to a ceramic sealing system between a rotor blade (120) and a housing (1''). By means of the combination of a small porous zirconium oxide layer (11) on a turbine rotor blade, which zirconium oxide layer faces a ceramic layer system (15', 15'') of higher porosity, durable sealing systems are achieved. The housing (1'') has a metal substrate (7), a metal adhesion-promoting layer (10), and a thick, outer, ceramic layer (15', 15'') based on zirconium oxide, in particular having a porosity ≥ 14%.

Description

Sealing system for blade and housing

The invention relates to ceramic sealing systems of turbine blades and housings.

To optimize radial gaps within stationary gas turbines so-called "Abradable Coatings" (abradable layers) are used, which should give the mechanical resistance of turbine blade tips in their thermal expansion and are abraded, so that a trench formed within a ceramic coating.

Often, its blade material rubbed off on the ceramic.

In aircraft engines, the blade tip is sometimes coated with cBN (cubic boron nitride) to provide an abrasive action on the run-in layers. cBN is a very hard material, which is well suited ceramic layers demolish ^¬ ben. However, it is not very temperature resistant (cerium ^¬ reduction with oxygen already 1273K), so that it is not suitable strip for stationary gas turbines with unknown times of arrival, since it burns before.

Other manufacturers of stationary gas turbines use so-called "engineered surfaces". These layers have recessed grooves introduced obliquely to the flow direction into the inlet layers, which are intended to facilitate burial. However, this has the consequence that turbulences or pressure losses at the recessed edges lead to a negative influence on the machine performance.

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

In the dependent claims further advantageous measures are listed, which are combined with each other Kings ^¬ nen to obtain further advantages.

1, 2 and 3 embodiments of He ^¬ invention, Figures 4 and 5, a turbine blade and a gas turbine.

The figures and the description represent only exemplary embodiments of the invention. FIG. 1 shows a first exemplary embodiment in which the

Turbine blade 120 as a component for a rotor 120 to the stator, a housing 1 ^λ (Fig. 1), 1 ^{λ λ} , 1 ^{λ λ λ} (Fig. 2, 3) opposite. The turbine blade 120 as part of a rotor 120 typically comprises a nickel- or cobalt-based superalloy in the substrate and has corresponding protective layers on the blade platform and the airfoil 25 (FIGS. 2, 3). These are metallic adhesion promoter layers and / or corrosion protection layers based on NiCoCrAlY, aluminides or platinum aluminides, in each case with an overlying ceramic layer or ceramic layer system (FIGS. 1, 2, 3), in particular with a layer thickness of the ceramic layer of at least 300 μm.

Similarly, two-layer ceramic coating system on the blade 25, as an underlying partially stabilized zirconium oxide layer with an overlying vollstabili ^¬ overbased zirconium oxide layer as the outer layer may be present with or without segmentation or a pyrochlore with a ceramic bonding layer, in particular based on zirconium oxide. A turbine blade tip 99, the stator 1 ^λ (Fig. 1), and 1 ^{λ λ,} ΐ ^{λ λ λ} (Fig. 2, 3) is directly opposite, is not provided with an armor. Here the invention takes a different direction by there a partially stabilized zirconium oxide layer 11 is applied with a lower porosity, total <8%, insbeson ^¬ particular <6%, with an advantageous layer ^¬ thickness between 50ym and 150ym (Fig. 1, 2, 3).

The zirconium oxide layer 11 differs from the ceramic layer seen on the blade, in particular by

Lagigkeit, porosity (at least 10% difference) or together ^¬ mensetzung (at least 10%, or other stabilizer).

The opposite layer system 4 ^λ on the housing 1 ^λ also has a substrate 7 with a metallic bonding coat 10, preferably based on NiCoCrAlY. The

NiCoCrAlY layer preferably has a layer thickness of 180ym to 300ym. A thick, partially stabilized zirconium oxide layer 13 is applied to the metallic adhesion promoter layer 10.

This ceramic layer 13 on the layer system 4 ^λ is a partially stabilized zirconium oxide layer having a porosity> 8%, in particular greater than 10% and layer thicknesses of at least 1300ym.

The porosity of this ceramic layer 13 is significantly higher and is 18% ± 4%. The partial stabilization (Fig. 1, 2, 3) is achieved preference ^¬ as yttria, but can also be other Stabili ^¬ catalysts such as calcium oxide, magnesium oxide, Yb ₂ Ü3 or Gd ₂ <0 ₃ he ^¬ ranges, the proportion of yttria ^¬ advantageous way legally is 8%.

The layer thickness of the ceramic layer 13 is preferably ^¬ at 1400ym ± 10%. In Figure 2, another embodiment is shown in which the turbine blade 120 the same protective coating on the airfoil 25, the blade platform and the

Zirconia coating 11 on the top 99 has.

On the other hand, the housing 1 ^{λ λ} as a layer housing 4 ^{λ λ} a two-layer ceramic coating 15 15 ^{λ λ} , also on a substrate 7 and a metallic adhesive layer 10, as described in Figure 1.

However, it is a ceramic bonding layer 15 18 ^λ (Fig. 3), which has a porosity of preferably 18% ± 4%, but only a maximum thickness of 500ym, particularly 300ym to 500ym. The ceramic layer 15 Anbindungs ^¬ ^λ 18 (Fig. 3) is a layer of oxide partially stabilized zirconia.

Than thicker, at least twice as thick outer ceramic layer 15 ^{λ λ} a fully stabilized zirconium oxide is used 15 ^{λ λ.}

The stabilization is preferably yttria he ^¬ ranges, but can also be achieved by other stabilizers (Fig. 1, 2, 3).

The proportion of yttria stabilizer is 20% to 48%. The layer thickness of the thick outer ceramic layer 15 ^{λ λ} , 18 ^{λ λ} (Figure 2, 3) is preferably at lOOym.

FIG. 3 shows a further exemplary embodiment of the invention.

The ceramic layer system 4 ^{λ λ λ} on the ceramic layers 18 18 ^{λ λ} is also double-layered and also has a ceramic bonding layer 18 as in ^¬ 2 written ^{¬ written} on.

By contrast, the thick, outer, ceramic layer 18 ^{λ λ} is partially stabilized, in particular with yttrium oxide, in particular with 8%. Stabilization can also be achieved by other stabilizer ^¬ lisa factors.

However, the porosity of the outer ceramic layer 18 ^{λ λ is} preferably 24% ± 3%.

The innovation is, on the one hand, the reinforcement of the ^blade tips 99 with a high-temperature-capable and phase-stable material.

The ceramic layers are so-called highly homogeneous porous layers.

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 having at its blade ^tip 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, 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 heat flow and form either a columnar crystalline

Grain structure (columnar, ie grains which run the entire length of the workpiece and here, in common usage, are referred to as directionally solidified) or a monocrystalline structure, ie the entire workpiece consists of a single crystal. In these processes, one must avoid the transition to globulitic (polycrystalline) solidification, since undirected growth necessarily involves transverse and longitudinal grain boundaries. those which negate the good properties of the directionally solidified or monocrystalline component.

The term generally refers to directionally solidified microstructures, which means both single crystals that have no grain boundaries or at most small angle grain boundaries, and stem crystal structures that have probably longitudinal 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.

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 wise or completely stabilized by yttrium oxide

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 can ^¬ ner to have better thermal shock resistance porous, micro- or macro-cracked pERSonal. 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 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 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 ^¬. In the direction of flow of a working medium 113, the hot gas channel 111 of a row of vanes 115 is followed by a series 125 formed of rotor blades 120. The vanes 130 are fastened to an inner housing 138 of a stator 143, whereas the rotor blades 120 of a row 125 are mounted on the rotor 103 by means of a turbine disk 133, for example are attached.

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 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 can have a directional structure, ie 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.

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.

The guide blade 130 has a guide blade root facing the inner housing 138 of the turbine 108 (not shown here) and a guide blade foot opposite

Guide vane head on. The vane head faces the rotor 103 and fixed to a mounting ring 140 of the stator 143.

Claims

claims

1. Ceramic sealing system between a stator (1

1 ^{λ λ} , 1 ^{λ λ λ} ) and a rotor (120),

in particular for a moving blade (120) and a housing (Γ, 1 ^λ \ 1 ^{λ λ λ} ) as a stator,

wherein the turbine blade (120) forms part of the rotor,

the (120) having a first coating on the rotor (120), and in particular the airfoil (25) of the turbine show ^¬ fel (120)

this coating has a partially stabilized zirconium oxide with a porosity of more than 8%,

or different from a coating (11) on one

Tip (99) of the rotor or the turbine blade (120), wherein on the tip (99) of the rotor (120) or the turbine blade ^¬ (120) a zirconium oxide layer (11) with a porosity kle in particular less than 6%, is applied,

whereas the stator (1 ^λ 1 ^{λ λ} 1 ^{λ λ λ)} a metal sub strate ^¬ (7)

a metallic adhesion promoter layer (10),

especially based on NiCoCrAlY,

especially with a layer thickness of 180ym to 300ym and a thick, outer,

especially greater than 1000,

ceramic layer (13; 15 15 ^{λ λ} ; 18 18 ^{λ λ} ) based on zirconium oxide,

in particular with a porosity ^ 14%.

2. Ceramic sealing system according to claim 1,

wherein the thick, outer ceramic layer (13) is a partially stabilized, single layer,

in particular with a porosity of 18% ± 4%.

3. A ceramic sealing system according to claim 1, wherein the ceramic layer (15 15 ^{λ λ,} 18 ^{λ λ} 18) is formed in two layers.

4. A ceramic sealing system according to claim 1 or 3, wherein an inner ceramic bonding layer (15 18 ^λ ) is present,

which in particular has partially stabilized zirconium oxide, in particular with a porosity of 18% ± 4%.

5. Ceramic sealing system according to claim 3 or 4, with an outer, at least twice as thick zirconium oxide layer (15 ^λ \ 18 ^{λ λ} ).

6. Ceramic sealing system according to one or more of claims 3, 4 or 5,

wherein the outer ceramic layer (15 ^{λ λ,} 18 ^{λ λ)} is Minim ^¬ least lOOOym thick,

in particular 100% ± 10%.

7. Ceramic sealing system according to one or more of claims 1, 3, 4, 5 or 6,

with a ceramic bonding layer (18 ^λ),

in particular on the basis of a partially stabilized yttrium oxide layer having a porosity of 18% ± 4% and an outer, highly porous, at least twice as thick partially stabilized zirconium oxide layer (18 ^{λ λ} ),

in particular with a porosity of 24% ± 3%.

8. Ceramic sealing system according to one or more of claims 1, 3, 4, 5 or 6,

with a ceramic bonding layer (15 ^λ ),

in particular based on a partially stabilized

Yttrium oxide layer with a porosity of 18% ± 4% and an outer, porous, at least twice as thick fully stabilized zirconium oxide layer (15 ^{λ λ} ),

in particular with a porosity of 18% ± 4%.

9. A ceramic sealing system according to claim 3, 4, 5, 6 or 8,

in which the full stabilization by yttrium oxide,

especially with a share of 48 ~ 6

he follows.

10. Ceramic sealing system according to one or more of claims 2, 3, 4, 5, 6, 7 or 8,

in which the partial stabilization by yttria with a

8% share takes place.

11. A ceramic sealing system according to one or more of claims 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10,

in which the stabilization of zirconium oxide is effected only by yttrium oxide.

12. Ceramic sealing system according to one or more of claims 3, 4, 5, 6, 7, 8, 10 or 11,

in which the thickness of the ceramic bonding layer (15 18 ^λ ) is between 300ym and 500ym,

especially at 400ym.

13. Ceramic sealing system according to one or more of the preceding claims,

in which the layer thickness of the ceramic layers (13; 15 \ 15 ^λ \ · 18 \ 18 ^{λ λ} ) lies on the housing (1 \ 1 ^λ \ 1 ^{λ λ λ} ) at 1300ym to 1500ym,

especially at 1400ym.

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

in which the ceramic layer (11) on the blade tip (99) is between 50 μm and 150 μm thick.

15. Ceramic sealing system according to one or more of the preceding claims,

in which a ceramic layer on the blade (25) has a layer thickness of at least 300 μm.