EP2099948A2

EP2099948A2 - Method for coating a component

Info

Publication number: EP2099948A2
Application number: EP07820464A
Authority: EP
Inventors: Thomas Berndt; Francis-Jurjen Ladru; Marcus Mensing; Gerhard Reich; Falk Stadelmaier
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2006-12-15
Filing date: 2007-09-21
Publication date: 2009-09-16
Also published as: US20100086757A1; WO2008071467A2; WO2008071467A3; EP1932936A1

Abstract

The invention relates to a method for coating a component with a multilayer ceramic coating, in which the individual layers of the ceramic coating are applied covering one another on the component, and in which ceramic particles are supplied to a coating burner, melted partly or completely by said coating burner, and deposited on the component, wherein ceramic particles with a particle size, which increases from layer to layer, are supplied to the coating burner. Furthermore, the invention relates to a multilayer ceramic coating and a component which is provided with a multilayer ceramic coating.

Description

Method for coating a component

The invention relates to a method for coating a component with a multilayer ceramic layer, in which individual layers of the ceramic layer are applied to one another in a covering manner on the component by supplying ceramic particles to a coating burner, completely or partially melting them and depositing them on the component. The invention further relates to a multilayer ceramic layer and a component which is provided with a multilayer ceramic layer.

Components, which are used in an aggressive atmosphere in a temperature range of greater than 800 ⁰ C, are often provided with protective coatings in order to prolong their service life. For example, gas turbine rotor blades or guide vanes are provided with ceramic-containing thermal barrier coatings or complex layer systems are applied which protect the blades against thermal, chemical and mechanical stresses.

The ceramic-containing thermal barrier coatings may contain, for example, zirconium oxides which are stabilized by yttrium oxides. As a method of application, among other plasma spraying is used. Powdered ceramic particles are supplied to a plasma coating burner in which they are completely or partially melted and then deposited on the component. The ceramic particles then form the thermal barrier coating on the surface of the component.

In many cases, the heat-insulating layer is formed in individual layers applied one above the other on the component, ie 4 - 15 layers with a layer thickness of 20-50 μm are applied one above the other at a standard layer thickness of 200-400 μm. A method for forming multilayer thermal barrier coatings on the surface of turbine blades is described in DE 100 22 157 C1. Here, pulverulent ceramic particles are supplied to the coating burner, where they are completely or partially melted and then deposited in the form of individual layers on the surface of the turbine blade. In this case, ceramic particles are used with different size grain size, the ceramic particles are melted by a suitable control of the burner performance depending on their size different degrees, ie the smaller ceramic particles melt completely and the larger ceramic particles are only superficially melted. In this way, the porosity of the individual layers of the thermal barrier coating can be varied.

The known in the prior art ceramic layers have a total thickness that is not above 450 microns. One of the reasons for this is that different problems occur in the production of ceramic thermal barrier coatings having a greater thickness.

If the thermal barrier coating is formed by applying individual superimposed layers, the layers already present on the component surface increasingly isolate during the application process in such a way that the newly applied coating material of the further layers can not release its heat. This leads to a build-up of heat, as a result of which the temperature of the newly applied layers increases, with the result that they become more densely compressed. By this compression, however, the porosity of the individual layers decreases, which on the one hand reduces their thermal insulation capability during operation of the component and on the other hand causes a much poorer adhesion of the layers to each other. Among other things, this can lead to a layer failure, ie there is a risk of local spalling of areas of the ceramic thermal barrier coating. It is therefore an object of the present invention, a method of the type mentioned in such a way that multilayer ceramic layers can be applied with a thickness greater than 450 microns on a component. The component is to be coated with the individual layers in such a way that they obtain sufficient porosity, which ensures both a high thermal insulation capability and a good adhesiveness of the layers to one another.

This object is achieved in that the coating burner from layer to layer ceramic particles are supplied with an increasingly larger grain size.

The basic idea of the invention is therefore to increase the grain size of the ceramic particles from layer to layer. First, the component is coated with a first layer by supplying the coating burner with ceramic particles having the smallest total grain size used, for example -53 μm + 11 μm. In order then to apply a second layer on the first layer, the coating burner ceramic particles are supplied with a grain size which is greater than that of the ceramic particles for the first layer. Subsequently, the further layers are applied analogously with a constant increase in the grain size of the ceramic particles used.

It is advantageous here that the effect of the compaction of the individual layers with increasing layer thickness is counteracted by increasing the grain size of the ceramic particles from layer to layer due to the heat accumulation occurring. Thus, the individual layers are formed with a nearly constant porosity, which on the one hand preserves their thermal insulation and on the other hand ensures the adhesion of the individual layers to each other. In this way, the risk of a shift failure is excluded.

According to a first embodiment of the invention it is provided that the performance of the coating burner during the application of the individual layers of the ceramic layer continuously ierlich adapted to the grain of the ceramic particles. In this way, it is possible during the coating process to control the porosity of the individual layers even more precisely, or to modify them. By adjusting the burner output, it is possible in particular to influence how much the ceramic particles are melted.

It is also possible to use a plasma burner as a coating burner. In this case, the performance of the plasma torch can be adjusted, for example, by the variation of the current intensity and / or the hydrogen gas flow and / or the argon gas rate. Thus, a current of 500-650 A, a hydrogen gas flow of 12-16 NLPM and an argon gas rate of 40-60 NLPM can be set. Optionally, gas mixtures of argon, nitrogen and

Hydrogen can be used, in particular mixing ratios Ar / N ₂ / H ₂ of 30-40 / 10-20 / 8-14 can be used.

The individual layers of the ceramic layer can be applied with a thickness in the range between 10 and 100 microns, in particular, a thickness between 20 - 50 microns is suitable. In this way, a ceramic layer is obtained, which has a high heat insulating ability and is mechanically stable.

In a further embodiment, the multilayer ceramic layer with a total thickness in the range between 100-1000 μm, in particular between 200 and 700 μm, particularly preferably between 250 and 600 μm, can be applied.

For example, ceramic particles having a particle size of -75 μm + 10 μm or -53 μm + 11 μm or -90 μm + 11 μm can be supplied to the coating burner for the first layer.

For the application of the last layer, ie the outermost layer of the multilayer ceramic layer, ceramic particles having a grain size of -106 μm + 11 μm or -125 μm + 45 μm or-150 μm + 75 μm can be supplied to the coating burner. Furthermore, the coating burner, a mixture of ceramic particles are supplied with at least two different grain sizes. By suitable mixing of the two differently granulated ceramic particle fractions, the total grain size of the ceramic particles fed to the coating burner can be varied in a simple manner.

It is likewise possible to apply a multilayer sublayer to the component before coating with the multilayer ceramic layer by supplying ceramic particles with a constant grain size to a coating burner, melting it completely or partially and then stacking it over the component in individual layers. Subsequently, the multilayer ceramic layer is formed on the underlayer.

Ceramic particles with a constant grain size of -75 μm + 10 μm or -53 μm + 11 μm or -90 μm + 11 μm can be supplied to the coating burner for the lower layer. In addition, the individual layers of the lower layer can be applied with a thickness in the range of 10-100 μm, in particular between 20-50 μm. The total thickness of the underlayer may range between 150 and 450 microns.

It is likewise possible for a multilayer upper layer to be applied to the multilayer ceramic layer by supplying ceramic particles to a coating burner, melting them completely or partially, and covering them over the multilayer ceramic layer in individual layers. In this case, the ceramic particles for the upper layer have a larger grain size than the ceramic particles which are supplied to the coating burner for applying the last layer of the multilayer ceramic layer.

The object of the invention is also achieved by a multilayer ceramic layer having the features of claim 14 and by a component having the features of claim 24. In the following the invention will be explained in more detail with reference to an embodiment with reference to the drawing. In the drawing shows:

Figure 1 is a schematic partial sectional view of a

Turbine blade with a multilayer ceramic layer according to the invention, and

FIG. 2 shows a schematic illustration of a device for coating a component,

FIG. 3 shows a gas turbine,

Figure 4 in perspective a turbine blade and

Figure 5 is a combustion chamber.

1 shows a schematic partial sectional view of a turbine blade 1, which is coated with a multi-layer ceramic layer 3 according to the invention. Under the multilayer ceramic layer 3 on the turbine blade 1, a multilayer underlayer 2 is formed and on the multilayer ceramic layer 2 there is a multilayer top layer 4. The underlayer 2, the multilayer ceramic layer 3 and the top layer 4 are respectively stacked one above another layers 2a, 3a -c, 4a formed.

The lower layer 2 is applied directly to the turbine blade 1. The layers 2a of the lower layer 2 consist of partially fused together ceramic particles with a constant grain size, wherein the grain size - 75 microns + 10 microns or - 53 microns + 11 microns or - 90 microns + 11 microns may be. The layers 2a of the lower layer 2 have a thickness in the range between 10 and 100 μm, in particular between 20 and 50 μm. The total thickness of the lower layer 2 is between 150 and 450 microns. On the lower layer 2, the multilayer ceramic layer 3 is applied flat. The individual layers 3a, 3b, 3c of the multilayer ceramic layer 3 are made of partially fused ceramic particles, wherein the ceramic particles from layer to layer increasingly have a larger grain size.

That The partially fused ceramic particles of the first layer 3a have a smaller grain size than the partially fused ceramic particles of the second layer 3. However, the two layers 3a, 3b have approximately the same porosity, so that both have a high heat insulation capability and a strong one Liability of the layers 3a, 3b is guaranteed to each other.

The layers 3a, 3b, 3c have a thickness in the range between 10-100 μm, in particular between 20-50 μm. The total thickness of the multilayer ceramic layer 3 is in the range between 100-1000 .mu.m, in particular between 200 and 700 .mu.m, and particularly preferably between 250 and 650 .mu.m.

On the multilayer ceramic layer 3, the multilayer upper layer 4 is applied flat. The upper layer 4 is formed by the superimposed layers 4a, which consist of partially fused ceramic particles. The grain size of these ceramic particles is greater than the grain size of the ceramic particles of the last layer 3 c of the multilayer ceramic layer 3.

On the one hand, the multilayer ceramic layer 3 has a high heat insulating capability and on the other hand has a high mechanical stability, so that the risk of layer failure is reduced.

In order to coat the turbine blade 1, in a first step the lower layer 2 is applied layer by layer to the surface of the turbine blade 1. For this purpose, ceramic particles with a constant grain size are fed to a coating burner, which is wholly or partly filled by it. melted and then deposited on the turbine blade in the individual layers 2a opaque one above the other.

In a second step, the multilayer ceramic layer 3 is then applied to the lower layer 2. To this end, ceramic particles are supplied to the coating burner, which particles are completely or partially melted by the latter and then deposited in the form of the layers 3a, 3b, 3c.

In the coating torch, for example, ceramic particles having a first grain size of -75 μm + 10 can be introduced for the first bearing of the multilayer ceramic layer 3.

The first layer 3a is applied on the surface of the lower layer 2 and the second layer 3b directly covering on the first layer 3a. In this case, ceramic particles with an increasingly larger grain size are supplied from layer to layer to the coating burner. That the ceramic particles supplied to the coating burner for forming the sheet 3b have a larger grain than the ceramic particles supplied to the coating burner for forming the sheet 3a. The ceramic particles with the largest grain size used for the multilayer ceramic layer 3 are finally completely or partially melted by the coating burner when the last layer 3c is deposited.

The variation of the grain sizes of the ceramic particles can be achieved, for example, by simultaneously supplying ceramic particles having at least two different grain sizes to the coating burner. In this case, by appropriate mixing of the two grains each increasing overall grain size can be obtained.

In addition, the performance of the coating torch can be continuously adapted to the grain size of the ceramic particles. Thus, the performance can be increased if increasingly larger ceramic particles are to be deposited. This will ensure that even the larger ceramic particles are sufficiently melted to be firmly integrated into the layers 3a, 3b, 3c with.

When a plasma torch is used as a coating torch, its performance can be adjusted by varying the current intensity and / or the hydrogen gas flow and / or the argon gas rate.

In a last step, the upper layer 4 is deposited over the entire surface on the multi-layer ceramic layer 3. For this purpose, ceramic particles having a constant grain size are completely or partially melted in the coating burner and deposited in a covering manner on the multilayer ceramic layer 3 in the individual layers 4a.

In this case, ceramic particles are used for the layers 4a, which have a larger grain size than the ceramic particles which were used for the last layer 3c of the multilayer ceramic layer 3. In this way, it is ensured that the layers 4a of the top layer 4 also receive a sufficient porosity and thus have both a high thermal insulation capability and good adhesion to one another.

FIG. 2 schematically shows a device 5 for coating a component, for example the turbine blade 1. The device 5 has three conveyor units 6a-c, each containing ceramic particles with a different size grain. The conveyor units 6a-c are each connected via lines 7 to a powder switch 8 and designed to supply the powder switch 8 ceramic particles. The powder switch 8 is designed to mix the supplied ceramic particles to a coating powder with uniform grain size. In this case, the resulting grain size of the coating powder depends on the quantities and grain sizes of the ceramic particles respectively supplied by the conveying units 6a-c. The powder switch 8 is connected via a line 7 with a powder injector 9. The powder injector 9 is arranged relative to a plasma torch 10 so that it can deliver a stream of coating powder 11 into the flame 12 of the plasma torch 10.

The device 5 may additionally have a control unit which controls the supply of the ceramic particles from the conveyor units 6a-c, and the function of the powder switch 8 and the powder injector 9. The controller may also be configured to regulate the power of the plasma torch, depending on the grain size of the coating powder, i. to increase its performance at a larger grain size, to ensure a sufficient melting of the ceramic particles. In addition to the three conveying units 6a-c shown, further conveying units may also be present.

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 with a shaft 101, which is also referred to as a turbine runner. 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 109. The annular combustion chamber 110 communicates with an example annular hot gas channel 111. There, for example, four successively connected turbine stages 112 form the turbine 108th

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, air 105 is sucked in by the compressor 105 through the intake housing 104 and compressed. The compressed air provided at the turbine-side end of the compressor 105 is supplied 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 the material for the components, in particular for the turbine blade 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 known; These documents are part of the disclosure regarding the chemical composition of the alloys.

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.

FIG. 4 shows a perspective view of a moving blade 120 or guide blade 130 of a turbomachine that 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 consecutively a fastening region 400, a blade platform 403 adjacent thereto and an airfoil 406 and a blade tip 415. As a guide blade 130, the blade 130 may have at its blade tip 415 another platform (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 blade 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 regarding the chemical composition of the alloy. 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, for example, by directed solidification from the melt. These are casting methods in which the liquid metallic alloy solidifies into a monocrystalline structure, ie a single-crystal workpiece, or directionally. 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 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 "directionally solidified microstructures" is used, it refers both to single crystals which have no grain boundaries or at most small-angle grain boundaries, and to stem crystal structures which are likely to be found in longitudinal grooves. grain boundaries, but have 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 Al known; these writings are part of the revelation regarding the solidification process.

Likewise, the blades 120, 130 may have coatings against corrosion or oxidation, e.g. 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 ones 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, which should be part of this disclosure with regard to the chemical composition of the alloy. 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 can still be present a thermal barrier coating, which is preferably the outermost layer, and consists for example of Zrθ2, Y2θ3-Zrθ2, 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. Suitable coating processes, such as electron beam evaporation (EB-PVD), produce stalk-shaped grains in the thermal barrier coating.

Other coating methods are conceivable, e.g. Atmospheric plasma spraying (APS), LPPS, VPS or CVD. The thermal barrier coating may have porous, micro- or macro-cracked grains for better thermal shock resistance. The thermal barrier coating is therefore preferably more porous than the MCrAlX layer.

The blade 120, 130 may be hollow or solid. If the blade 120, 130 is to be cooled, it is hollow and may still film cooling holes 418 (indicated by dashed lines) on.

FIG. 5 shows a combustion chamber 110 of the gas turbine 100. The combustion chamber 110 is designed, for example, as a so-called annular combustion chamber, in which a multiplicity of windings are arranged around an axis of rotation 102 in the circumferential direction

Burners 107 open into a common combustion chamber space 154, the flames 156 produce. 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 enable a comparatively long service life for 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.

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).

Each heat shield element 155 made of an alloy is equipped on the working fluid side with a particularly heat-resistant protective layer (MCrAlX layer and / or ceramic coating) or is made of high-temperature-resistant material (solid ceramic blocks). 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, which should be part of this disclosure with regard to the chemical composition of the alloy.

On the MCrAlX may also be present, for example, a ceramic thermal insulation layer and consists for example of ZrC> 2, Y2Ü3-Zrθ2, ie it is not, partially or fully ^¬ dig stabilized by yttrium 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.

Other coating methods are conceivable, e.g. atmospheric plasma spraying (APS), LPPS, VPS or CVD. The thermal barrier coating may have porous, micro- or macro-cracked grains for better thermal shock resistance.

Refurbishment means that turbine blades 120, 130, heat shield elements 155 may have to be freed from protective layers after their use (eg by sandblasting). This is followed by removal of the corrosion and / or oxidation layers or products. Optionally, cracks in the turbine blade 120, 130 or the heat shield element 155 are also repaired. After that a re-coating of the turbine blades 120, 130, heat shield elements 155 and a renewed use of the turbine blades 120, 130 or the heat shield elements 155

Claims

claims

1. A method for coating a component (1) with a multilayer ceramic layer (3), wherein the individual layers (3a-c) of the ceramic layer (3) on the component (1) are applied to each other by supplying ceramic particles to a coating burner, of be completely or partially melted and deposited on the component (1),

characterized in that

the ceramic coating of layer (3a) to layer (3b) ceramic particles are supplied with an increasingly larger grain size, on the multilayer ceramic layer (3) a multilayer top layer (4) is applied by ceramic particles supplied to a coating burner, of this completely or partially melted and on the multilayer ceramic layer (3) in individual layers (4a) are applied to each other covering one another, wherein the ceramic particles for the upper layer (4) have a greater grain size than the ceramic particles which the coating burner during application of the last layer (3c) of the multilayer ceramic layer ( 3) are supplied.

2. The method according to claim 1, characterized in that

the performance of the coating burner during the application of the individual layers (3a-c) of the ceramic layer (3) is continuously adapted to the grain size of the ceramic particles.

3. The method according to claim 2, characterized in that

a plasma torch is used as a coating burner.

4. The method according to claim 3, characterized in that

the performance of the plasma torch by a variation of the

Amperage and / or the hydrogen gas flow and / or the argon gas rate is adjusted.

5. The method according to any one of the preceding claims, characterized in that

the individual layers (3a-c) of the ceramic layer with a thickness in the range between 10 and 100 .mu.m, in particular between see see 20 to 50 microns are applied.

6. The method according to any one of the preceding claims, characterized in that

the multilayer ceramic layer (3) having a total thickness in the range between 100 to 1000 .mu.m, in particular between 200 and 700 .mu.m and particularly preferably between 250 and 650 microns is applied.

7. The method according to any one of claims 1 to 6, characterized in that the coating burner for the first layer (3a) ceramic particles with a grain size of

- 75 microns + 10 microns or - 53 microns + 11 microns or - 90 microns + 11 microns are supplied.

Method according to one of claims 1 to 7, characterized in that

the coating burner for the last layer (3c) ceramic particles with a grain size of - 106 microns + 11 microns or - 125 microns + 45 microns or - 150 microns + 75 microns are supplied.

9. The method according to any one of claims 1 to 7, characterized in that

the coating burner, a mixture of ceramic particles is supplied with at least two different grain sizes.

10. The method according to any one of claims 1 to 9, characterized in that

prior to coating, a multilayer underlayer (2) is applied to the component (1) by supplying ceramic particles with a constant grain size to a coating burner, completely or partially melted by the latter and covering each other on the component (1) in individual layers (2a) become.

11. The method according to claim 10, characterized in that

the coating burner for the formation of the lower layer (2) ceramic particles with a constant grain size of - 75 microns + 10 microns or - 53 microns + 11 microns or - 90 microns + 11 microns are supplied.

12. The method according to any one of claims 10 or 11, characterized in that

the individual layers (2a) of the lower layer (2) are applied with a thickness in the range between 10 and 100 μm, in particular between 20 and 50 μm.

13. The method according to any one of claims 10 to 12, characterized in that

the lower layer (2) is applied with a total thickness in the range between 150 and 450 μm.

14. Multi-layer ceramic layer (3), in which individual layers (3a-c) are arranged one above the other in a covering manner, wherein the individual layers (3a-c) consist of partially fused ceramic particles, characterized in that

the ceramic particles from layer (3a) to layer (3b) increasingly have a larger grain size, on the multilayer ceramic layer (3) a multilayer

Upper layer (4) is applied, which consists of individual covering one above the other

Layers (4a), wherein the individual layers (4a) consist of partially fused ceramic particles whose grain size is greater than the grain size of the ceramic particles of the last layer

(3c) of the multilayer ceramic layer (3).

15. Multi-layer ceramic layer (3) according to claim 14, characterized in that

the layers (3a-c) have a thickness in the range between 10 and 100 μm, in particular between 20 and 50 μm.

16. Multi-layer ceramic layer (3) according to any one of claims 14 or 15, characterized in that

their total thickness is in the range between 100 to 1000 .mu.m, in particular between 200 and 700 .mu.m and particularly preferably between 250 and 650 microns.

17. Multi-layer ceramic layer (3) according to any one of claims 14 to 16, characterized in that

the ceramic particles of the first layer (3a) have a grain size of -75 μm + 10 μm or -53 μm + 11 μm or -90 μm + 11 μm.

18. Multi-layer ceramic layer (3) according to any one of claims 14 to 17, characterized in that

the ceramic particles of the last layer (3c) have a grain size of - 106 μm + 11 μm or - 125 μm + 45 μm or - 150 μm + 75 μm.

19. Multi-layer ceramic layer (3) according to any one of claims 14 to 16, characterized in that

the ceramic particles have at least two different grain sizes.

20. Multi-layer ceramic layer (3) according to any one of claims 14 to 19, characterized in that

it is applied to a lower layer (2), which consists of individual layers (2a) arranged one above the other, wherein the individual layers (2a) consist of partially fused ceramic particles with a constant grain size.

21. Multi-layer ceramic layer (3) according to claim 20, characterized in that

the ceramic particles of the lower layer (2) have a constant grain size of - 75 μm + 10 μm or - 53 μm + 11 μm or - 90 μm + 11 μm.

22. Multi-layer ceramic layer (3) according to any one of claims

20 or 21, characterized in that

the layers (2a) of the lower layer (2) have a thickness in the range between 10 to 100 μm, in particular between 20 to 50 μm.

23. Multi-layer ceramic layer (3) according to any one of claims 20 to 22, characterized in that

the total thickness of the lower layer (2) is between 150 and 450 μm.

24. component (1), in particular a component of a gas turbine, which is provided with a mehrlagiqen ceramic layer (3) according to any one of claims 15 to 23.