EP1807554A2 - Electrolyte for deposition of an alloy and method for electrolytic deposition - Google Patents

Abstract

Electrolyte for electrodeposition of alloys in which the matrix material of the alloy is dissolved and containing another component in powder form. An independent claim is included for depostion of a layer from the electrolyte.

Description

 Electrolyte for the deposition of an alloy and method for the electrolytic deposition

The invention relates to an electrolyte for depositing an alloy according to claim 1 and an electrodeposition process according to claim 23.

Electrolytic coating processes use an electrolyte in which the elements to be deposited either in one

Solution dissolved or dispersed as powder particles in a

Solution are available.

However, alloys can be deposited poorly in this way.

It is therefore an object of the invention to overcome this problem.

The object is achieved by an electrolyte according to claim 1, by at least the matrix material, i. H. the component of the alloy with the largest relative proportion of the layer to be deposited is dissolved in the electrolyte and further constituents are dispersed as a powder in the electrolyte and deposited according to claim 23.

In the dependent claims further advantageous measures are listed, which can be combined with each other in an advantageous manner.

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FIG. 1 shows a turbine blade,

Figure 2 is a combustion chamber

Figure 3 is a gas turbine and

FIG. 4 Composition of alloys which can be deposited from an electrolyte according to the invention. According to the invention, the electrolyte for the electrolytic deposition of an alloy is a solution of at least the element of the matrix material and furthermore contains dispersed powder. Solved means that the component is present as an ion in a solution (water, alcohol, acid, lye, ...).

The matrix material may be either cobalt or nickel. In addition to the matrix material, at least one further element of the alloy may be dissolved in the electrolyte. Thus, nickel and cobalt may be dissolved in the electrolyte.

The powder containing the further constituents of the alloy can have either chromium or aluminum or chromium and aluminum.

Likewise, the powder may comprise the elements chromium, aluminum and yttrium.

In addition to the elements chromium, aluminum and yttrium, silicon and / or rhenium may also be present as dispersed powder in the electrolyte.

In the case of so-called MCrAlX alloys, the matrix material consists of nickel or cobalt.

The alloy consists for example of at least three elements, in particular of at least five elements (eg.

NiCoCrAlX). The electrolyte contains, for example, at least one of the elements chromium, aluminum as a dispersed powder.

Also, melting point depressants such as B, Si, Hf, Zr may be dissolved in the electrolyte or may be present as a powder.

Likewise, coatings based on superalloys can be deposited with the electrolyte according to the invention. For an electrolyte used to deposit a superalloy layer or to repair a superalloy substrate, the powder contains For example, the elements titanium, tantalum, tungsten, molybdenum, niobium, boron, zirconium or carbon.

With a corresponding electrolysis apparatus, layers can be deposited on a substrate by means of the electrolytes according to the invention. After the electrolytic production of the layer, a heat treatment can be carried out in order, for example, to achieve a better bonding of the electrolytically produced layer to the substrate. In a further step, further metallic and / or ceramic layers can be applied to the electrolytically produced layer.

A drawback with a prior art electrolytic process is that it is very difficult for an alloy to dissolve all components in the solution.

The other possibility, namely to disperse all constituents as powder in the solution, leads to the problem that the deposition process is very strongly determined by the PuI distributions of the matrix material, which occupies a large volume fraction. This often leads to an irregular or uncontrolled deposition of alloying elements with a smaller volume or weight fraction. The electrolyte of the invention solves the problem in that the largest proportion (matrix material) of the alloy to be deposited is dissolved and the other elements are present as a powder.

Likewise, the electrolyte according to the invention opens up the possibility of varying the stoichiometry of the alloy during the electrolytic deposition by varying the proportions of powder by constantly increasing the proportion of an alloying element by adding powder, for example, and thus grading the concentration of this alloying element in the layer to be produced reached.

embodiments I. The desired composition of an MCrAlX alloy consists at least of (in wt%):

20-22% chromium, 10.5-11.5% aluminum,

0.3-0.5% yttrium,

1.5-2.5% rhenium,

11-13% cobalt and

Rest of nickel.

In this case cobalt and nickel are dissolved in the electrolyte and the powder which is added to the aqueous electrolyte consists, for example, of (in wt%)

61.8% chromium, 32.3% aluminum,

0, 9% yttrium and

5% rhenium.

II. Another MCrAlX alloy consists at least of (in wt%):

27-29% chromium,

7-8% aluminum,

0.5-0.7% yttrium, 0.3-0.7% silicon,

29-31% nickel and

Balance cobalt.

In this case, the elements cobalt and nickel are dissolved in the electrolyte again and the powder has, for example, the following weight distributions: 76.5% chromium, 20.5% aluminum, 1, 6% yttrium and 1.4% silicon.

III. Another embodiment of an MCrAlX alloy is 16-18% chromium, 12-13% aluminum, 0.5-0.7% yttrium, 0.3-0.5% silicon, 21-23% cobalt and balance nickel.

In turn, cobalt and nickel are dissolved in the electrolyte and the powder has, for example, the following parts by weight: 56.7% chromium, 40% aluminum, 2% yttrium, 1.3% silicon.

IV. Another embodiment of an MCrAlX alloy: 16-18% chromium, 9.5-11% aluminum, 0.3-0.5% yttrium, 1-1.8% rhenium, 24-26% cobalt, balance nickel ,

Again cobalt and nickel are dissolved in the electrolyte and the powder contains 58.8% chromium, 34.6% aluminum, 1.4% yttrium and 5.2% rhenium.

As an example of the composition of a superalloy, mention may be made here by way of example of IN 738 from FIG. 4 with the proportions:

15-17% chromium, 3.2-3.7% aluminum, 3.2-3.7% titanium,

1.5-2.0% tantalum,

2.4-2.8% tungsten,

1.5-2.0% molybdenum, 0, 6-1.1% niobium,

0.0007-0.012% boron,

0.015-0.06% zirconium,

8-9% cobalt,

Rest of nickel.

Here are cobalt and nickel, for example, also in the back

Electrolytes dissolved and the powder has, for example, the following constituents in wt%:

53.8% chromium, 11.4% aluminum,

11.4% titanium,

5.9% tantalum,

8.7% tungsten,

5, 9% molybdenum, 2.8% niobium,

0.03% boron,

0.13% zirconium.

Other layers of superalloys according to FIG. 4 are likewise produced in this way.

1 shows a perspective view of a moving blade 120 or guide blade 130 of a turbomachine, which 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, a fastening area 400, an adjacent blade platform 403 and an airfoil 406, one after another.

As a guide blade 130, the blade 130 may have another platform at its blade tip 415 (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 Christmas tree or Schwalbenschwanzfuß are possible.

The blade 120, 130 has a leading edge 409 and a trailing edge 412 for a medium flowing past the airfoil 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 with regard to the chemical compositions of the superalloy.

The blade 120, 130 can in this case by a casting process, also by means of directional solidification, by a Schmiedever- drive, be made 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, i.e., grains that run the full length of the workpiece and here, in common usage, are referred to as directionally solidified) or a monocrystalline structure, i. the whole workpiece 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. 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.

Likewise, the blades 120, 130 may have coatings against corrosion or oxidation (MCrAlX; M is at least one element 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, whose chemical compositions are intended to be part of this disclosure. These layers can be applied electrolytically using the method according to the invention.

On the MCrAlX may still be a thermal barrier layer and consists for example of ZrC> 2, Y2Ü4-Zrθ2, i. it is not, partially or completely stabilized by yttrium oxide 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.

Refurbishment means that components 120, 130 may need to be stripped of protective layers 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 may still have film cooling holes 418 (indicated by dashed lines).

FIG. 2 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 large number are arranged around the rotation axis 102 in the circumferential direction Burners 107 open into a common combustion chamber space. 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 lend a comparatively long service life to these operating parameters, which are unfavorable 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.

Each heat shield element 155 is equipped on the working medium side with a particularly heat-resistant protective layer or made of high-temperature-resistant material. These may be solid ceramic stones or alloys with MCrAlX and / or ceramic coatings.

The materials of the combustion chamber wall and its coatings may be similar to the turbine blades.

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 combustion chamber 110 is designed in particular for detecting losses of the heat shield elements 155. For this purpose, a number of temperature sensors 158 are positioned between the combustion chamber wall 153 and the heat shield elements 155.

FIG. 3 shows by way of example a gas turbine 100 in a longitudinal partial section. The gas turbine 100 has inside a rotatably mounted about a rotation axis 102 rotor 103, which is also referred to as a turbine runner. Along the rotor 103 follow one another a suction housing 104, a compressor 105, for example, a toroidal combustion chamber 110, in particular annular combustion chamber 106, with a plurality of coaxially arranged burners 107, a turbine 108 and the exhaust housing 109th

The ring combustion chamber 106 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 a 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 guided to the burners 107 and mixed there 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 seen in the flow direction of the working medium 113 first Turbine stage 112 is most thermally stressed in addition to the heat shield bricks lining the annular burners 106.

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.

Likewise, blades 120, 130 may be anti-corrosion coatings (MCrAlX; M is at least one member 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). 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 A1, which are intended to be part of this disclosure.

On the MCrAlX, a thermal barrier coating may still be present, consisting for example of ZrC> 2, Y2Ü4-ZrO2, i. it is not, partially or completely stabilized by yttrium oxide 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 vane 130 has a guide vane foot (not shown here) facing the inner housing 138 of the turbine 108 and a vane head opposite the vane foot. The vane head faces the rotor 103 and fixed to a mounting ring 140 of the stator 143.

Claims

claims 1. electrolyte for the electrolytic deposition of an alloy in which at least the matrix material of the alloy is dissolved as an ion to the electrolyte and in which at least one further component of the alloy to be deposited is contained as a powder. 2. Electrolyte according to claim 1, characterized in that the matrix material is cobalt. 3. Electrolyte according to claim 1, characterized in that the matrix material is nickel. 4. Electrolyte according to claim 1, 2 or 3, characterized in that the alloy consists of at least three elements, in particular of at least five elements and in particular of the type MCrAlX, where M is at least one element of the group iron (Fe), cobalt (Co), nickel (Ni), X is an active element and for yttrium (Y) and / or silicon (Si) and / or hafnium (Hf) and / or at least one element of Rare earth stands. 5. Electrolyte according to claim 1, 2, 3 or 4, characterized in that at least one further element of the alloy is dissolved in the electrolyte in addition to the element of the matrix material. 6. An electrolyte according to claim 1, 2, 3, 4 or 5, characterized in that Nickel and cobalt are dissolved in the electrolyte. 7. An electrolyte according to claim 1, characterized in that the powder contains at least chromium 8. An electrolyte according to claim 1 or 7, characterized in that the powder contains at least aluminum. 9. An electrolyte according to claim 1, 7 or 8, characterized in that the powder contains at least yttrium. 10. The electrolyte according to claim 1 or 7 to 9, characterized in that the powder contains at least silicon. 11. An electrolyte according to claim 1 or 7 to 10, characterized in that the powder contains at least rhenium. 12. An electrolyte according to claim 1, 3 or 4, characterized in that the alloy which can be deposited from the electrolyte at least consists of (in wt%) 20-22% chromium, 10.5-11.5% aluminum, 0.3-0.5% yttrium, 1.5-2.5% rhenium, 11-13% cobalt and balance nickel. 13. Electrolyte according to one or more of claims 4 to 12, characterized that cobalt and nickel are dissolved in the electrolyte and that the powder consists of (in wt%) 61.8% chromium, 32.3% aluminum, 0, 9% yttrium and 5% rhenium. 14. An electrolyte according to claim 1, 2 or 4, characterized in that the alloy which can be deposited from the electrolyte at least consists of (in wt%) 27-29% chromium, 7-8% aluminum, 0.5-0.7% yttrium, 0.3-0.7% silicon, 29-31% Nickel and balance cobalt. 15. Electrolyte according to one or more of claims 4 to 11 or 14, characterized that in the electrolyte nickel and cobalt are dissolved and that the powder consists of (in wt%) 76.5% chromium, 20.5% aluminum, 1.6% yttrium, 1.4% silicon. 16. An electrolyte according to claim 1, 3 or 4, characterized in that the alloy which can be deposited from the electrolyte at least consists of (in wt%) 16-18% chromium, 12-13% aluminum, 0.5-0.7% yttrium, 0.3-0.5% silicon, 21-23% cobalt and Rest of nickel. 17. An electrolyte according to one or more of claims 4 to 11 or 16, characterized that in the electrolyte nickel and cobalt are dissolved and that the powder consists of (in wt%) 56.7% chromium, 40% aluminum, 2% yttrium, 1.3% silicon. 18. An electrolyte according to claim 1, 3 or 4, characterized in that the alloy which can be deposited from the electrolyte at least consists of (in wt%) 16-18% chromium, 9.5-11% aluminum, 0.3-0.5% yttrium, 1-1.8% rhenium, 24-26% cobalt, Rest of nickel. 19. An electrolyte according to one or more of claims 4 to 11 or 18, characterized that in the electrolyte nickel and cobalt are dissolved and that the powder consists of (in wt%) 58.8% chromium, 34.6% aluminum, 1.4% yttrium, 5.2% rhenium. 20. An electrolyte according to claim 1 or 3, characterized the alloy which can be deposited from the electrolyte, at least is (in wt%) 15-17% chromium, 3.2-3.7% aluminum, 3.2-3.7% titanium, 1.5-2.0% tantalum, 2.4-2.8 % Tungsten, 1.5-2.0% molybdenum, 0.6-1.1% niobium, 0.0007-0.012% boron, 0.015-0.06% zirconium, 8-9% cobalt, balance nickel. 21. An electrolyte according to claim 5 or 20, characterized the powder consists of (in wt%) 53.8% chromium, 11.4% aluminum, 11.4% titanium, 5.9% tantalum, 8.7% tungsten, 5, 9% molybdenum, 2.8% niobium, 0.03% boron, 0.13% zirconium and Cobalt and nickel are dissolved in the electrolyte. 22. An electrolyte according to claim 1, 5 or 6, characterized the alloy which can be deposited from the electrolyte contains a melting point depressant. 23. A method of depositing a layer using an electrolyte according to one or more of the preceding claims. 24. The method according to claim 23, characterized in that during the electrolytic deposition, powder of an alloying ingredient is added to the electrolyte so that the concentration of that alloying ingredient increases, thereby producing a graded layer.