EP1526192A1 - Electrolytic process for depositing a graded layer on a substrate and component - Google Patents

Abstract

The electroplating process, to deposit a coating on a substrate (13) or component, gives a graduated coating layer by altering the composition of the electrolyte (7) at timed intervals. The electrolyte within the bath (4), has at least two components (28,31), with an additional feed of the second component (31) in time intervals (t) to alter the electrolyte composition, or the first component (28) is taken out at least partially. The first component is a metal, especially an alloy, or a ceramic; and the second component is metallic. The electrolyte is agitated mechanically. The current/voltage pulses (40) are rectangular or triangular.

Description

The invention relates to an electrolytic method for deposition a graded layer on a substrate according to claim 1 and a component produced by this method according to claim 21.

Various methods are known to apply layers to apply a substrate. These are e.g. Plasma spraying, galvanic deposition or vapor deposition, etc.

An article by G. Devaray in the Bulletin of Electrochemistry 8 (8), 1992, pp. 390-392 entitled "Electro deposited composites" a review on new technologies for aerospace and other field "gives an overview of electrochemical processes Deposition of layers.

DE 101 13 767 A1 discloses an electrolytic plating method.

DE 39 43 669 C2 discloses a method and a device for electrolytic surface treatment, in which a Mixing of the mass parts used for coating by vibration movement and / or rotational movement takes place, so deposited a uniform electrolytic layer becomes.

Other electrolytic coating processes are known from GB 2 167 446 A, EP 443 877 A1 and from the Article by J. Zahavi et al in Plating and Surface Finishing, Jan. 1982, p. 76 ff. "Properties of electrodeposited composite Coatings "in which undissolved particles in the electrolyte used to deposit these in the layer with.

In Electrochemical Society Proceedings Vol. 95-18, p. 543 et seq. by Sarhadi et al. entitled "Development of a low current density electroplating bath ... "is the use of Baths described the cobalt, nickel or iron compounds contain.

US Pat. No. 6,375,823 B1 describes an electrolytic coating method, when using an ultrasound probe becomes.

DE 195 45 231 A1 describes a method for electrolytic Deposition of metal layers, in which a pulse current or pulse voltage method is used. this will however only applied to aging phenomena of separation baths to reduce.

US 2001/00 54 559 A1 discloses an electrolytic coating process, where pulsed currents are used, around the unwanted evolution of hydrogen during prevent electrolytic coatings of metals.

DE 196 53 681 C2 discloses a method for electrolytic Deposition of a pure copper layer in which a Pulse current or pulse voltage method is used.

DE 100 61 186 C1 describes a method for galvanic Deposition using periodic current pulses become.

V. Sova describes in the article "Electrodeposited composite coatings for protection from high temperature corrosion "in Trans IMF 1987, 65, 21ff an electrolytic deposition process, in the electrolyte in the undissolved particles for the applied layer to be applied. Likewise, the application described by pulse currents.

With the known methods applied layers under the conditions of some purposes a bad one Adhesion to the substrate. Besides, only materials can be used a constant composition are deposited.

It is therefore an object of the invention to solve the above problems to overcome.

The object is achieved by an electrolytic process for depositing a graded layer on a substrate according to Claim 1 and a component according to claim 21.

Due to the temporal variation of the composition of the electrolyte the production of graded layers becomes the liability of layers on the substrate and possibly with each other improved, since abrupt material transitions are to be avoided.

Further advantageous embodiments of the method and of the component are listed in the subclaims.
The method steps of the subclaims and the measures for improving the component can be combined with each other in an advantageous manner.

Embodiments of the invention are closer in the figures explained.

Figur 1

eine Vorrichtung, mit der das erfindungsgemäße Verfahren durchzuführen ist,

Figur 2

eine Sequenz von Strom/Spannungspulsen, die für ein erfindungsgemäßes Verfahren verwendet werden kann,

Figur 3

den zeitlichen Verlauf des erfindungsgemäßen Verfahrens,

Figur 4a,b,c

verschiedene Beispiele für eine Gradientenschicht,

Figur 5

eine Gasturbine und

Figur 6

eine Brennkammer.

Show it:

FIG. 1

a device with which the method according to the invention is to be carried out,

FIG. 2

a sequence of current / voltage pulses that can be used for a method according to the invention,

FIG. 3

the time course of the method according to the invention,

FIG. 4a, b, c

different examples of a gradient layer,

FIG. 5

a gas turbine and

FIG. 6

a combustion chamber.

FIG. 1 shows, by way of example, schematically a device 1 with which the method according to the invention is to be carried out. Arranged in a container 4 are an electrolyte 7, an electrode 10 and a component as substrate 13 to be coated.
The substrate 13 to be coated is, for example, a turbine component (turbine blade 120, 130 (FIG. 5), a combustion liner 155 (FIG. 6) or another housing part of a steam or gas turbine 100 (FIG. 5)) made of an iron, nickel or cobalt base superalloy and may already have a layer (MCrAlX) on its surface.

The component 13 can either be newly manufactured or remanufactured.
Refurbishment means that after use, components may be separated from layers (thermal barrier coating) and corrosion and oxidation products removed, for example by acid treatment (acid stripping). If necessary, cracks still have to be repaired. Thereafter, such a component can be coated again. The reprocessing is economically interesting because the substrate 13 is very expensive.

The substrate 13 and the electrode 10 are via electrical Supply lines 19 with a current or voltage source 16 electrically connected. The current or voltage source 16 may be pulsed electrical currents or voltages (FIG. 2) produce.

In the electrolyte 7, for example, the individual components 28, 31 of an alloy are included, which are to be deposited on the substrate 13. For example, the electrolyte 7 contains the first constituent 28 and the second constituent 31 of an alloy.
By suitable choice of the process parameters (FIG. 2), the components 28, 31 are deposited on the substrate 13. The components 28, 31 may be metallic and / or ceramic. Also, all components may be metallic or ceramic only.

Likewise, gradients in the chemical composition can be produced in the layer to be produced by suitable choice of the process parameters.
For example, an alloy MCrAlX is deposited on the substrate 13, wherein M stands for at least one element of the group iron, cobalt or nickel. The introduction of the alloying elements Cr, Al, X and optionally further elements is carried out either by adding suitable soluble salts to the electrolyte or by suspending fine-grained, insoluble powders in the galvanic bath, which deposit as solid particles. For example, at least two components are dissolved, for example, in the form of salts in the electrolyte 7.

By a subsequent thermal process, the deposited Be homogenized or compacted layer or certain phases can be set in the layer.

An ultrasonic probe 22 disposed in the electrolyte 7 can be and is controlled by an ultrasonic generator 25, improves the hydrodynamics and the mixing of the ingredients 28, 31 in the region of the substrate 13 and accelerated the deposition process.

For each component 28, 31 of the alloy, the current / voltage level, set the pulse duration and the pause become.

FIG. 2 shows an example of a sequence of current pulses that repeat themselves.
A sequence 34 consists of at least two blocks 37.
Each block 37 consists of at least one, in particular two or more current pulses 40.
A current pulse 40 is characterized by its duration t _on , its height I _max and its shape (rectangle, triangle, ...). Equally important as process parameters are the pauses between the individual current pulses 40 (t _off ) and the pauses between the blocks 37.

The sequence 34 consists for example of a first block 37 with three current pulses 40, between which in turn one Pause takes place. This is followed by a second block 37, the has a greater current level and six current pulses 40th consists. After another pause, four current pulses 40 follow in the reverse direction, i. with changed polarity, um a correction of the alloy composition, the hydrogen desorption or to achieve an activation.

The conclusion of the sequence 34 is followed by a further block 37 four current pulses. The sequence 34 can be repeated several times be varied and also temporally.

The individual pulse times t _on are preferably of the order of magnitude of about 1 to 100 milliseconds. The duration of the block 37 is on the order of up to 10 seconds, so that up to 5000 pulses are emitted in a block 37.

The occupancy both during the pulse sequences as well as in the Pause time with a low potential (base current) is optional possible. Thus, an interruption of the electrodeposition, which can cause inhomogeneities avoided.

A block 37 is matched with its parameters to a component 28, 31 of the alloy in order to achieve the best deposition of this constituent 28, 31. These can be determined in individual experiments. An optimized block 37 leads to an optimized deposition of the component optimized for this block 37, ie the duration and the type of deposition is improved. The other ingredients are also still deposited.
This optimization can be carried out for at least one further, for example all components 31 of the alloy.
Thus, the optimized composition of the components 28, 31 is achieved.

For example, by the duration of the individual blocks 37, the proportion of the constituents 28, 31 in the layer to be applied can be determined.
Gradients can also be generated in the layer. This is done by the parameters of the block 37, which is optimally matched to a component 28, 31, extended or shortened accordingly.

Likewise, other non-alloy components, such as e.g. Secondary phases in which electrolytes 7 are contained and deposited become.

FIG. 3 shows the time course of the method according to the invention.
The device 1 comprises an electrolyte 7, the first component 28 is for example metallic and has the composition MCrAlX.

Among constituents 28, 31 of the electrolyte 7 are particles, dissolved salts ,. if necessary plus wetting agents or additives understood that give the constituents 28, 31 in the layer to be produced.
In a known manner, an MCrAlX layer is deposited electrolytically on the component 13.
Over time, at least a second, further constituent 31 is fed into the container 4 and supplied to the electrolyte 7 and increases its concentration, so that the composition of the electrolyte 7 changes. This can be done in one step or the concentration of the ingredient 31 is increased continuously over time so that the concentration of the first ingredient 28 decreases in percentage. Thus, the composition of the electrolyte 7 is varied over time. Therefore, the component 13 need not be introduced into different containers 4 with different electrolytes 7. The second component 31 may also be present in the electrolyte 7 from the beginning and then further increased.
The concentration of wetting agents and other additives can also be varied.

Also, the composition of the electrolyte 7 in addition to the addition of the component 31, possibly also be varied via an outlet valve 40, is discharged through the electrolyte 7 with the component 28, so that also by the concentration of the further constituent 31 in the electrolyte. 7 elevated.
The further constituent 31 is likewise deposited, with the result that a layer graded according to the increase in the concentration of the constituent 31 results. The graded layer is a composite material and is also referred to as a composite.
At the beginning of the process, a matrix is formed with the constituent 28 containing the secondary phase 31, the proportion of which may vary within the matrix.

The proportion of constituent 31 can also be increased in this way that inversely the matrix through the component 31 and the secondary phase is formed by the component 28.

FIG. 4 shows, by way of example, layer systems which are described by FIGS temporal variation of the composition of the electrolyte 7 can arise.

FIG. 4 a shows a substrate 50 on which a layer 53 has been deposited electrolytically.

In a first method step, only the constituents 28 were deposited, as was explained in FIG. 3 for the first method step. A layer 54 is formed which has only the composition of constituent 28.
In a further method step, the concentration of the further constituent 31 was increased in one step, so that the material composition of the layer 55 to be deposited changes.
Thus, on the layer 54 forms a further layer 55, which comprises the constituents of the electrolyte 7, consisting of the constituents 28, 31.
It forms a layer system 53.

Graduated layers can also be produced by continuously increasing the addition of the constituent 31 in the electrolyte 7 over time t, or by removing the electrolyte 7 with the constituent 28. Thus, for example, a layer results as shown in FIG. 4b.
On the substrate 50, in turn, at first only one layer has been formed, which results from the component 28 of the electrolyte.
By continuous or discontinuous increase in time of the constituent 31 in the electrolyte 7, the concentration (c31) of this constituent 31 in the layer 55 increases to the outside.

But it can also be from the beginning of the component 31 to the electrolyte 7 are added, so that a concentration gradient directly from the substrate 50 forms.

FIG. 4c shows a further layer system 53, which has been produced by the method according to the invention.
The layer system 53 has multi-graded layers 54, 55.
Thus, in a first layer 54 on the substrate 50, the concentration of the material of the substrate 50 falls outwardly to the end of the layer 54 or earlier to a certain value, zero here.
At the same time, the concentration of the constituent 28 of the first layer 54 increases.
For example, after the concentration of the component 28 is 100%, the concentration of the component 28 in the second layer 55 decreases again.
The value of the concentration of the component 28 may decrease to zero or a value other than zero. At the same time, the concentration of the constituent 31 in the layer 55 increases accordingly.

The substrate 50 consists for example of an iron-, nickel- or cobalt-based superalloy, the layer 54 may be an MCrAlX layer on which a ceramic thermal barrier coating 55 (ZrO ₂ ) is applied.

The concentration of the ingredients 28, 31 can also be through Variation of the deposition parameters such as current density, voltage, Pulse and pause time are additionally influenced by these parameters of the current / voltage pulses specifically to the Abscheidungsverhalten the component 28, 31 are adjusted.

FIG. 5 shows a gas turbine 100 in a partial longitudinal section.

The gas turbine 100 has inside about a rotation axis 102 rotatably mounted rotor 103, which also serves as a turbine runner referred to as. Along the rotor 103 follow each other an intake housing 104, a compressor 105, an example Toroidal combustion chamber 110, in particular annular combustion chamber 106, with several coaxially arranged burners 107, a turbine 108 and the exhaust housing 109. The annular combustion chamber 106 communicates with an example annular Hot gas channel 111. There form, for example, four turbine stages 112 connected in series, the turbine 108. Each turbine stage 112 is formed of two blade rings. As seen in the flow direction of a working medium 113 follows in the hot gas duct 111 of a guide vane 115 a from Blades 120 series 125 formed.

The vanes 130 are attached to the stator 143, whereas the blades 120 of a series 125 by means of a Turbine disk 133 are mounted on the rotor 103. On the rotor 103 is coupled to a generator or a work machine (not shown).

During operation of the gas turbine 100 is from the compressor 105 sucked and compressed by the intake 104 104 air 135. The provided at the turbine end of the compressor 105 compressed air is fed to the burners 107 and mixed there with a fuel. The mixture is then to form the working medium 113 in the combustion chamber 110 burned. From there, the working medium flows 113 along the hot gas channel 111 past the vanes 130 and the blades 120. Relaxed on the blades 120 the working medium 113 is pulse-transmitting, so that the blades 120 drive the rotor 103 and this the attached to him work machine.

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 direction of flow of the working medium 113, are subjected to the greatest thermal stress in addition to the heat shield bricks lining the annular combustion chamber 106. In particular, they have a substrate, a directional structure, ie, they are monocrystalline (SX) or longitudinal (DS structure). In order to withstand the temperatures prevailing there, they are cooled by means of a coolant.
Likewise, the blades 120, 130 can be coatings against corrosion (MCrAlX, M = Fe, Co, Ni, X = Y, rare earths) and heat (thermal barrier coating, for example of ZrO ₂ or Y ₂ O ₄ -ZrO ₂ in the form of stalk-shaped grains ( EP-PVD)), which are graded and prepared by the method described above.

The vane 130 has an inner housing 138 of the Turbine 108 facing Leitschaufelfuß (not shown here) and a vane foot opposite Guide vane head on. The vane head is the rotor 103 facing and on a mounting ring 140 of the stator 143rd established.

FIG. 6 shows a combustion chamber of a gas turbine.
The combustion chamber 110 is configured, for example, as a so-called annular combustion chamber, in which a plurality of burners 102 arranged around the turbine shaft 103 in the circumferential direction 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 turbine shaft 103 around.

To achieve a comparatively high efficiency the combustor 110 for a comparatively high temperature the working medium M of about 1000 ° C to 1600 ° C designed. Around even with these, for the materials unfavorable operating parameters to allow a comparatively long service life is the combustion chamber wall 153 on its the working medium M facing side with one of heat shield elements 155 formed inner lining provided. Each heat shield element 155 is working medium side with a particularly heat-resistant Protective layer produced according to the invention can be equipped or made of high temperature resistant Material made. Due to the high temperatures inside the combustion chamber 110 is also for the heat shield elements 155 or provided for the holding elements, a cooling system.

The combustion chamber 110 is in particular for a detection of Losses of the heat shield elements 155 designed. These are between the combustion chamber wall 153 and the heat shield elements 155, a number of temperature sensors 158 are positioned.

Claims (23)

Method for depositing a composite material comprising at least two components (28, 31) as at least one graded layer (53, 54, 55) on a substrate (13, 50),
in an electrolytic process,
wherein the substrate (13, 50) for a certain period of time in an electrolyte (7),
to apply a layer (54, 55) is introduced,
characterized in that
the quantitative composition of the constituents (28, 31) of the electrolyte (7) is varied over time,
to achieve grading of the at least one layer (54, 55). Method according to claim 1,
characterized in that
the substrate (13, 50) is arranged in a container (4) filled with the electrolyte (7),
and that the time variation of the composition of the electrolyte (7) by supplying the at least second component (31) into the container (4). Method according to claim 1 or 2,
characterized in that the substrate (13, 50) is arranged in a container (4),
that the temporal variation of the composition of the electrolyte (7) takes place thereby,
that the electrolyte (7) with the at least first component (28) is at least partially removed from a container (4) of the electrolyte (7), and
that the at least second component (31) is supplied. Method according to claim 1 or 3,
characterized in that
the first component (28) is metallic, in particular an alloy. Method according to claim 1 or 3,
characterized in that
the first component (28) is ceramic. Method according to claim 1 or 2,
characterized in that
the at least second component (31) is ceramic. Method according to claim 1 or 2,
characterized in that
the at least second component (31) is metallic. Method according to claim 1 or 4,
characterized in that
for electrolytic deposition at least one current / voltage pulse (40) is used,
to optimize the deposition of the individual alloy components (28, 31) and / or
to promote the gradation of the layer (53, 54, 55). Method according to claim 1 or 8,
characterized in that
the electrolyte (7) is set in mechanical vibration,
in particular by an ultrasound probe (22). Method according to claim 8,
characterized in that
for electrolytic deposition a current / voltage pulse (40) is used, which is determined in its time course in particular by a rectangular or triangular shape. Method according to claim 8 or 10,
characterized in that
for electrolytic deposition using both positive and negative current / voltage pulses (40). A method according to claim 8, 10 or 11
characterized in that
several current / voltage pulses (40) are used for the electrolytic deposition,
each summarized in a sequence (34),
wherein the sequence (34) consists of at least two different blocks (37),
wherein a block (37) consists of at least one, in particular at least two current pulses (40). Method according to claim 12,
characterized in that
a block (37) is determined by a number of current pulses (40), pulse duration (t _on ), pulse pause (t _off ), current level (I _max ) and time course. Method according to claim 12 or 13,
characterized in that
a block (37) is in each case matched to a component (28, 31) of the alloy,
to achieve the best deposition of constituent (28, 31). Method according to claim 12 or 13,
characterized in that
each block (37) is tuned to a respective component (28, 31) of the alloy,
to achieve the best composition of ingredients (28, 31). Method according to claim 4 or 8,
characterized in that
as a layer, an MCrAlX alloy is deposited on the substrate (13, 50),
where M is at least one element of the group iron, cobalt or nickel,
and X is yttrium and / or at least one element of the rare earths. Method according to claim 8, 12, 13 or 16,
characterized in that
In an alloy layer to be produced, gradients in the material composition are influenced by temporal variation of the current / voltage pulse (40) or the sequence (34). Method according to claim 8, 10 or 11,
characterized in that
a base current is superimposed on the current pulses (40) and / or the pauses. Method according to claim 1,
characterized in that
a turbine blade (120, 130), a combustion chamber lining (155) or other housing parts of a steam or gas turbine (100) are coated as the substrate (13, 50). Method according to claim 19,
characterized in that
as the substrate (13, 50) a newly manufactured component or a remanufactured component is coated. component
a substrate (13, 50)
and at least one layer (53, 54, 55),
which is graded and manufactured according to one or more of the preceding claims. Component according to claim 21,
characterized in that
on the substrate (50) a first graded layer (54) of a first material (28) is applied, and
a second graded layer (55) is applied to the first graded layer (54),
wherein the concentration of the first material (28) decreases from the substrate (50) in the layer (55). Component according to claim 21 or 22,
characterized in that
starting from the substrate (50), the concentration of the substrate (50) in the first layer (54) decreases and the concentration of the first material (28) in the layer (54) increases.

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