EP1976660A1

EP1976660A1 - Method for the production of a hole

Info

Publication number: EP1976660A1
Application number: EP07712002A
Authority: EP
Inventors: Thomas Beck; Silke Settegast
Original assignee: Siemens AG
Current assignee: Siemens AG; Chromalloy Gas Turbine Corp
Priority date: 2006-01-24
Filing date: 2007-01-05
Publication date: 2008-10-08
Also published as: EP2853338A1; CN101374629A; RU2397852C2; EP1810774A1; WO2007085516A1; EP2589457A1; EP2853338B1; RU2008134515A; JP2009523616A; CA2639932A1

Abstract

Conventional methods for producing a hole in a component are time-consuming and costly as special lasers featuring short laser pulse durations are used. In the inventive method, the laser pulse durations are varied, short laser pulse durations being utilized only in the area to be removed in which an influence on the penetration behavior and discharge behavior is noticeable while longer pulse durations of >0.4ms are used. This is the case for the inner surface (12) of a diffuser (13) of a hole (7), for example, which can be produced very accurately by means of short laser pulse durations.

Description

Method of making a hole

The invention relates to a method for producing a hole according to claim 1, wherein by means of pulsed

Energy rays in a component a hole is produced.

In the case of many components, in particular castings, subsequent removal, such as depressions or through holes, must be generated sooner. Especially with turbine components, which have cooling holes for cooling, holes are inserted later after the production of the component.

Such turbine components often also include layers, such as e.g. a metallic layer or intermediate layer and / or a ceramic outer layer. The film cooling holes must then be created through the layers and the substrate (casting).

US Pat. No. 6,172,331 and US Pat. No. 6,054,673 disclose a laser drilling method for inserting holes in layer systems using ultrashort laser pulse lengths. It is selected from a specific laser pulse length range, a single laser pulse length and thus generates the entire hole.

DE 100 63 309 A1 discloses a method for producing a cooling air opening by means of a laser, in which the laser parameters are adjusted so that material is removed by sublimation.

U.S. Patent No. 5,939,010 discloses two alternative methods of producing a plurality of holes. In one method (Figures 1, 2 of the US patent), a hole is first completely created before the next hole is made. In the second method, the holes are generated stepwise by first a first portion of a first hole, then a first portion of a second hole, etc. is generated (Fig. 10 of the US-PS). Different pulse lengths can be used in the two methods, but always the same pulse lengths within one of these two methods. The two methods can not be linked. The cross-sectional area of the area to be removed always corresponds to the cross-section of the hole to be produced.

U.S. Patent No. 5,073,687 discloses the use of a laser to make a hole in a component made from a

Substrate is formed with double-sided copper layer. In this case, a hole is first generated by a copper film by means of a longer pulse duration and then by means of shorter pulses a hole in the substrate, consisting of a resin, wherein subsequently a hole through a copper layer on the back with higher output power of the laser is generated. The cross-sectional area of the removed area corresponds to the cross-section of the hole to be produced.

US Pat. No. 6,479,788 B1 discloses a method for producing a hole in which longer pulse lengths are used in a first step than in a further step. The pulse duration is varied here in order to produce the best possible rectangular shape in the hole. The cross-sectional area of the beam is also increased as the pulse length decreases.

The use of ultrashort laser pulses is very time-consuming and therefore expensive because of their low average power.

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

The object is achieved by a method according to claim 1, in which different pulse lengths and for longer pulse lengths pulse lengths of> 0.4 ms are used. It is particularly advantageous if shorter pulses are used in only one of the first removal steps in order to produce optimum properties in an outer upper region of the separation surface, since these are decisive for the outflow behavior of a medium out of the hole and for the flow around a medium around this hole , Inside the hole, the properties of the interface are rather uncritical, so that longer pulses can be used there, which can cause inhomogeneous interfaces.

In the dependent claims of the method further advantageous measures of the method or the device are listed. The measures listed in the subclaims can be combined with each other in an advantageous manner.

The invention will be explained in more detail with reference to FIGS.

FIG. 1 shows a hole in a substrate,

FIG. 2 shows a hole in a layer system,

FIG. 3 shows a plan view of a through hole to be produced;

FIGS. 4 to 11 removal steps of the method according to the invention,

FIGS. 12-15 are apparatuses for carrying out the method,

FIG. 16 shows a gas turbine,

17 shows a turbine blade and

Figure 18 is a combustion chamber. Description of the component with hole

FIG. 1 shows a component 1 with a hole 7. The component 1 consists of a substrate 4 (for example a casting or DS or SX component).

The substrate 4 may be metallic and / or ceramic. Particularly in the case of turbine components, such as turbine runners or guide vanes 130 (FIGS. 16, 17), heat shield elements 155 (FIG. 18) and other housing parts of a steam or gas turbine 100 (FIG. 16), but also of an aircraft turbine, the substrate consists 4 made of a nickel-, cobalt- or iron-based superalloy. In turbine blades for aircraft, the substrate 4 is made of, for example, titanium or a titanium-based alloy. The substrate 4 has a hole 7, which is preferably a through hole. But it can also be a blind hole. The hole 7 consists of a lower portion 10, which starts from an inner side of the component 1 and which is preferably formed symmetrically (for example, circular, oval or rectangular), and an upper portion 13, optionally as a diffuser 13 on an outer surface 14 of the substrate 4 is formed. The diffuser 13 is a broadening of the cross section with respect to the lower portion 10 of the hole 7. The hole 7 is, for example, a film cooling hole. In particular, the inner surface 12 of the diffuser 13, ie in the upper region of the hole 7, should be smooth, because unevenness undesirable turbulence, deflections generate to allow an optimal outflow of a medium, in particular a cooling medium from the hole 7. On the quality of the hole surface in the lower portion 10 of the hole 7 significantly lower requirements are made, since the flow behavior is thereby affected only slightly. Figure 2 shows a component 1, which is designed as a layer system.

At least one layer 16 is present on the substrate 4. This may be, for example, a metallic alloy of the type MCrAlX, where M is at least one element of the group

Iron, cobalt or nickel. X stands for yttrium and / or at least one element of the rare earths. The layer 16 may also be ceramic.

Preferably, the component 1 is a layer system in which on the MCrAlX layer 16 'still another layer 16' 'is present, for example, a ceramic layer as a thermal barrier coating. The thermal barrier coating 16 "is, for example, a completely or partially stabilized zirconium oxide layer, in particular an EB-PVD layer or plasma-sprayed (APS, LPPS, VPS), HVOF or CGS (cold gas spraying) layer.

In this layer system 1, a hole 7 with the lower portion 10 and the diffuser 13 is also introduced.

The following comments on the production of the hole 7 apply to substrates 4 with and without layer 16 or layers 16 ', 16 ".

3 shows a plan view of a hole 7. The lower portion 10 could be made by a machining process. By contrast, this would not be possible with the diffuser 13 or only with great effort.

The hole 7 can also extend at an acute angle to the surface 14 of the component 1. method

Figures 4, 5 and 6 show removal steps of the method according to the invention. According to the invention, energy beams 22 having different pulse lengths are used during the process.

The energy beam may be an electron beam, laser beam or high pressure water jet. In the following, only an example of the use of a laser will be discussed.

In particular, in one of the first Abtragungsschritte shorter pulse lengths (tpuls <<) preferably less than or equal to 500ns, in particular less than 100ns used. Pulse lengths in the range of picoseconds or femtoseconds can also be used.

When using shorter pulse lengths of less than or equal to 500 ns (nanoseconds), in particular less than or equal to 100 ns, almost no melting occurs in the region of the interface. Thus, no cracks are formed on the inner surface 12 of the diffuser 13 and exact, planar geometries can be generated. The shorter pulse lengths are all shorter in time than the longer pulse lengths.

In one of the first removal steps, a first portion of the hole 7 in the component 1 is generated. This can for example at least partially or completely correspond to the diffuser 13 (FIGS. 6, 9). The diffuser 13 is mostly arranged in a ceramic layer. In particular, a shorter pulse length is used to produce the entire diffuser 13. In particular, a constant shorter pulse length is used to produce the diffuser 13. The time for producing the diffuser 13 in the method corresponds, for example, to the first removal steps.

In the production of the diffuser 13, a laser 19, 19 ', 19''with its laser beams 22, 22', 22 '' preferably in a lateral plane 43 back and forth, as it is shown for example in Figure 5. The diffuser 13 is traveled meandering along a travel line 9, for example, in order to remove material in one plane (step FIG. 4 according to FIG. 6).

Preferably, but not necessarily, when a metallic interlayer 16 'or substrate 4 is reached, longer laser pulse lengths (tpuls>) greater than 0.4ms, more preferably greater than 0.5ms, and most preferably up to 10ms, are used to fill the remaining lower portion 10 of the hole generate, as shown in Figure 1 or 2. The diffuser 13 is located at least for the most part in a ceramic layer 16 '', but may also extend into a metallic intermediate layer 16 'and / or into the metallic substrate 4, so that even metallic material is also partially removed with shorter pulse lengths can.

In particular, to generate the lower region 10 of the hole 7, substantially or completely longer, in particular temporally constant, pulse lengths are used. The time to

Production of the lower region 10 corresponds in the process to the last removal steps.

When using longer laser pulses, the at least one laser 19, 19 ', 19''with its laser beams 22, 22', 22 '', for example, not in the plane 43 moves back and forth. Since the energy due to the heat conduction in the material of the layer 16 or the substrate 4 is distributed and new energy is added by each laser pulse material is removed by material evaporation over a large area material in such a way that the surface in which the material is removed, about the Cross-sectional area A of the produced through-hole 7, 10 corresponds. This cross-sectional area can be adjusted via the energy output and pulse duration as well as the guidance (position of the focus at a horizontal distance from the surface 14) of the laser beam 22. The laser pulse lengths of a single laser 19 or a plurality of lasers 19 ', 19 "may, for example, be changed continuously, for example from the beginning to the end of the method. The process begins with the removal of material at the outer surface 14 and ends upon reaching the desired depth of the hole 7.

For example, the material is progressively stratified in planes 11 (FIG. 6) and in an axial direction 15.

Likewise, the pulse lengths can also be changed discontinuously. Preferably, only two different pulse lengths are used during the process. In the case of the shorter pulse lengths (for example ≦ 500 ms), the at least one laser 19, 19 'is moved and, for example, 0.4 ms for the longer pulse lengths, because the energy input anyway occurs over a larger area than the cross section of the energy input Laser beam corresponds.

While editing, the remaining part of the

Surface protected with a powder layer, in particular with a mask according to EP 1 510 593 Al. The powders (BN, ZrÜ ₂ ) and the particle size distribution according to EP 1 510 593 A1 are part of this disclosure for the use of a mask.

This is particularly useful when a metallic substrate or a substrate is processed with a metallic layer that does not yet have a ceramic layer.

laser parameters

When using pulses with a specific pulse length, the output power of the laser 19, 19 ', 19' ', for example, constant.

At the longer pulse lengths, an output power of the

Lasers 19, 19 ', 19' 'of several 100 watts, in particular 500

Watt used.

For the shorter laser pulse lengths, an output power of the laser 19, 19 'of less than 300 watts is used.

For example, a laser 19, 19 'having a wavelength of 532 nm is used only to produce shorter laser pulses.

With the longer laser pulse lengths, in particular a laser pulse duration of> 0.4 ms, in particular up to 1.2 ms, and a

Energy (joule) of the laser pulse from 6J to 21J, in particular

> 10J used, with a power (kilowatts) of 10kW up

50kW, especially 20kW is preferred.

The shorter pulse lengths have an energy in the single-digit or two-digit millijoule range (mJ), preferably in the single-digit millij oule range, wherein the used

Performance is mostly in the single-digit kilowatt range.

Number of lasers

In the method, one laser 19 or two or more lasers 19 ', 19 "can be used, which are used simultaneously or successively. The similar or different lasers 19, 19 ', 19 "have, for example, different regions with regard to their laser pulse lengths. For example, a first laser 19 'can generate laser pulse lengths less than or equal to 500ns, in particular less than 100ns, and a second laser 19''can generate laser pulse lengths greater than 100ns, in particular greater than 500ns. To generate a hole 7, the first laser 19 'is first inserted. For further processing, the second laser 19 "is then used or vice versa.

In the production of the through hole 7, only one laser 19 can be used. In particular, a laser 19 is used, which for example has a wavelength of 1064 nm and which can generate both the longer and the shorter laser pulses.

Sequence of the hole areas to be produced

FIG. 7 shows a cross section through a hole 7. Here, rough machining with laser pulse lengths greater than 100 ns, in particular greater than 500 ns, and fine machining with laser pulse lengths less than or equal to 500 ns, in particular less than or equal to 100 ns, first take place. The lower portion 10 of the hole 7 is completed and only a portion of the diffuser 13 is largely with a

Laser 19, the laser pulse lengths greater than 100ns, in particular greater than 500ns has processed (first removal steps). For the completion of the hole 7 or of the diffuser 13, only a thin outer edge region 28 in the region of the diffuser 13 has to be processed by means of a laser 19, 19 ', 19 "which can produce laser pulse lengths less than or equal to 500 ns, in particular less than 100 ns ( last removal steps). The laser beam 22, 22 ', 22''is preferably moved. FIG. 8 shows a plan view of a hole 7 of the component 1. The various lasers 19, 19 ', 19 "or the different laser pulse lengths of these lasers 19, 19', 19" are used in different removal steps. First, for example, a rough machining with large laser pulse lengths (> 100ns, especially> 500ns). As a result, most of the hole 7 is generated. This inner region is identified by the reference numeral 25. Only an outer edge region 28 of the hole 7 or the diffuser 13 must be removed in order to reach the final dimensions of the hole 7. In this case, the laser beam 22, 22 'in the plane of the surface 14 is moved.

Only when the outer edge region 28 has been processed by means of a laser 19, 19 'with shorter laser pulse lengths (≦ 500 ns, in particular <100 ns), the hole 7 or the diffuser 13 is completed.

The contour 29 of the diffuser 13 is thus produced with shorter laser pulses, whereby the outer edge region 28 is removed finer and more precisely and is therefore free of cracks and fusions.

The material is removed, for example, in a plane 11 (perpendicular to the axial direction 15).

Likewise, in the case of the longer pulse lengths, the cross-section A of the region to be removed can be constantly reduced down to A 'in the production of the hole 7 into the depth of the substrate 4, so that the outer edge region 28 is reduced in comparison to FIG. 7 (FIG. 9). This is done by adjusting energy and pulse duration.

An alternative in the production of the hole 7 is first to the outer edge region 28 with shorter laser pulse lengths (≤ 500ns) to an axial depth 15, which corresponds to an expansion of the diffuser 13 of the hole 7 in this direction 15 partially or completely generate (Fig. 10, the inner region 25 is indicated by dashed lines). In this case, the laser beam 22, 22 'is moved in these first removal steps in the plane of the surface 14. Thus, almost no fusions are generated in the area of the separating surface of the diffuser 13 and no cracks are formed there and exact geometries can thus be produced.

Only then is the inner region 25 removed with longer laser pulse lengths (> 100 ns, in particular> 500 ns) (last removal steps).

The methods can be applied to newly manufactured components 1, which were poured for the first time. Likewise, the process can be used with components to be reprocessed 1. Refurbishment means that components 1 that were in use, for example, are separated from layers and repaired, such as e.g. Filling of cracks and removal of oxidation and corrosion products can be recoated. Here, for example, impurities or coating material which has been applied again (FIG. 11) and has entered the holes 7 are removed with a laser 19, 19 '. Or special formations (diffuser) in the layer area are newly produced after re-coating during work-up.

reprocessing

FIG. 11 shows the refurbishment of a

Hole 7, wherein in a coating of the substrate 4 with the material of the layer 16 material has penetrated into the already existing hole 7. For example, the areas lying deeper in the region 10 of the hole 7 can be processed with a laser having laser pulse lengths greater than 100 ns, in particular greater than 500 ns. These areas are labeled 25. The more critical edge region 28, for example in the region of the diffuser 13, on which contamination is present, is processed with a laser 19 'having laser pulse lengths less than or equal to 500 ns, in particular less than 100 ns.

contraption

Figures 12 to 15 show exemplary devices 40, in particular to perform the inventive method. The devices 40 consist of at least one optic 35, 35 ', in particular at least one lens 35, 35', which directs at least one laser beam 22, 22 ', 22' 'onto the substrate 4 in order to produce the hole 7. There are one, two or more lasers 19, 19 ', 19' 'present. The laser beams 22, 22 ', 22' 'can be guided via mirrors 31, 33 to the optics 35, 35'.

The mirrors 31, 33 are displaceable or rotatable so that, for example, only one laser 19 ', 19' 'can transmit its laser beams 22' or 22 '' to the component 1 via the mirrors 31 or 33 and the lens 35.

The component 1, 120, 130, 155 or the optics 35, 35 'or the mirrors 31, 33 are movable in one direction 43, so that the laser beam 22, 22' is moved over the component 1, for example according to FIG.

The lasers 19, 19 ', 19' 'may, for example, have a wavelength of either 1064 nm or 532 nm. The lasers 19 ', 19' 'can have different wavelengths: 1064nm and 532nm. With regard to pulse length, for example, the laser 19 'can be set to pulse lengths of 0.1 to 5 ms; however, the laser 19 'on pulse lengths of 50 - 500ns.

By moving the mirrors 31, 33 (FIGS. 12, 13, 14), in each case the beam of the laser 19 ', 19''can be coupled with such laser pulse lengths to the component 1 via the optics 35, which are necessary, for example, to the outer one Edge region 28 or the interior 25 produce. FIG. 12 shows two lasers 19 ', 19'', two mirrors 31, 33 and an optic in the form of a lens 35.

If, for example, first the outer edge region 28 according to FIG. 6 is produced, then the first laser 19 'is coupled in with the shorter laser pulse lengths.

If the inner region 25 is then produced, the first laser 19 'is decoupled by movement of the mirror 31, and the second laser 19 "is coupled in by its movement of the mirror 33 with its longer laser pulse lengths.

FIG. 13 shows a similar device as in FIG. 12, but here two optics, here for example two lenses 35, 35 ', are present which allow the laser beams 22', 22 "of the lasers 19 ', 19" to be different Areas 15, 28 of the component 1, 120, 130, 155 are directed simultaneously.

For example, when an outer edge region 28 is created, the laser beam 22 'may be directed to a first location of this envelope-shaped region 28 and to a second location diametrically opposite the first location such that the processing time is significantly shortened.

The optics 35 for the first laser beams 22 'and the second optics 35' for the second laser beams 22 "can be used.

According to this device 40, the lasers 19 ', 19 "could be used sequentially or simultaneously with the same or different laser pulse lengths.

In FIG. 14, there are no lenses in the form of lenses, but only mirrors 31, 33 which hold the laser beams 22 ', 22 ". to steer on the component 1 and be used by movement that at least laser beam 22 ', 22''is moved in a plane over the component.

The lasers 19 ', 19 "can also be used simultaneously here.

FIG. 15 shows a device 40 with only one laser 19, in which the laser beam 22 is directed onto a component 1, for example via a mirror 31.

Again, an optics, for example in the form of a lens is not necessary. The laser beam 22 is moved, for example, by movement of the mirror 31 over the surface of the component 1. This is necessary when using shorter laser pulse lengths. With the longer laser pulse lengths, the laser beam 22 does not necessarily have to be moved so that the mirror 31 is not moved, as in the process stage.

Likewise, however, one lens or two lenses 35, 35 'can also be used in the device according to FIG. 15 in order to simultaneously direct the laser beam to different regions 25, 28 of the component 1, 120, 130, 155.

Compo le

FIG. 16 shows by way of example a gas turbine 100 in a longitudinal partial section.

The gas turbine 100 has inside a to a

Rotation axis 102 rotatably mounted 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 annular annular hot gas channel 111, for example. There, for example, four successively connected turbine stages 112 form the

Turbine 108.

Each turbine stage 112 is, for example, two

Shovel rings formed. As seen in the flow direction of a working medium 113 follows in the hot gas channel 111 a

Leitschaufelreihe 115 one formed of blades 120

Series 125.

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 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 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 it flows Working fluid 113 along the hot gas channel 111 past the vanes 130 and the blades 120. On the blades 120, the working fluid 113 relaxes momentum transfer, so that the blades 120 drive the rotor 103 and this the machine coupled to him.

The components exposed to the hot working medium 113 are subject to thermal loads during operation of the gas turbine 100. The vanes 130 and

Blades 120 of the first turbine stage 112 seen in the direction of flow 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 a material for the components, in particular for the

Turbine blades 120, 130 and components of the combustion chamber 110 are used, for example, iron-, nickel- or cobalt-based superalloys. 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 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. 17 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, 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; These documents are part of the disclosure regarding the chemical composition of the alloy.

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 Frasverfahren 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 warm flow and form either a prismatic crystalline grain structure (columnar, i.e. grains extending throughout the length of the work piece and here, in common parlance, referred to as directionally solidified) or a monocrystalline structure, i. the whole work consists of a single crystal. In these processes, it is necessary to avoid the transition to globulitic (polycrystalline) solidification, since non-directional growth necessarily forms transverse and longitudinal grain boundaries which negate the good properties of the directionally solidified or monocrystalline component. If the term "directionally solidified" is generally used, it means both single crystals which have no grain boundaries or at most small-angle grain boundaries, and also stem crystal structures which have grain boundaries that are probably in the longitudinal direction but no transverse grain boundaries. In these second-mentioned crystalline

Structures are also called directionally solidified structures.

Such methods are known from US Pat. No. 6,024,792 and EP 0 892 090 A1; 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).

On the MCrAlX may still be present a thermal barrier coating, which is preferably the outermost layer, and consists for example of ZrO ₂ , Y ₂ O ₃ -ZrO ₂ , ie it is not, partially or completely stabilized by yttria and / or calcium oxide and / or magnesium oxide.

The thermal barrier coating covers the entire MCrAlX layer. By suitable coating methods, e.g. Electron beam evaporation (EB-PVD) produces stalk-shaped grains in the thermal barrier coating. Other coating methods are conceivable, 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 possibly still has film cooling holes 418 (indicated by dashed lines), which are produced by the method according to the invention. FIG. 18 shows a combustion chamber 110 of the gas turbine 100. The combustion chamber 110 is configured, for example, as a so-called annular combustion chamber, in which a multiplicity of burners 107 arranged around a rotation axis 102 in the circumferential direction open into a common combustion chamber space 154, which generate flames 156. 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 from 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, for example, and may still have cooling holes (not shown) which open into the combustion chamber space 154 and are produced by the method according to the invention.

Each heat shield element 155 made of an alloy is equipped on the working medium 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 can 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 still be present, for example, a ceramic thermal barrier coating and consists for example of ZrC> 2, Y2θ3-ZrC> 2, 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. 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 need to be deprotected (e.g., by sandblasting) after use. 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. This is followed by 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

Method for producing a hole (7) in a layer system (1, 120, 130, 155) comprising at least one metallic substrate (4) and one outermost ceramic layer (16 '') by means of at least one pulsed energy beam (22 , 22 ',

22 "), in particular by means of at least one pulsed laser beam (22, 22 ', 22' ') at least one laser (19, 19', 19 ''), the (22, 22 ', 22' ') has a pulse length, wherein the method is carried out in a plurality of ablation steps, wherein shorter pulse lengths and longer pulse lengths are used, wherein in one of the first ablation steps different pulse lengths are used as in one of the last ablation steps and wherein the longer pulse lengths have pulse lengths of> 0.4ms.

2. The method according to claim 1,

in which during the removal steps with shorter pulse lengths the at least one energy beam (22, 22 ', 22'') is moved over the surface of the component (1, 120, 130, 155) in order to produce material in the region of a plane of the hole (7) to be produced ablate.

3. The method according to claim 1 or 2,

in which longer pulse lengths are used during the first ablation steps than in one of the last ablation steps.

4. The method according to claim 1 or 2,

in which shorter pulse lengths are used during the first ablation steps than in one of the last ablation steps.

5. The method according to claim 1, 2 or 3,

wherein the longer pulse lengths are used to remove a metallic interlayer (16 ') or the metallic substrate (4).

6. The method according to claim 1, 2, 3, 4 or 5,

in which the pulse length is continuously changed during the progress of the process for producing the hole (7).

7. The method of claim 1, 2, 3, 4 or 5,

wherein the pulse length is discontinuously changed as the method of forming the hole (7) progresses.

8. The method of claim 1, 3, 5, 6 or 7,

where a constant longer pulse length is used.

9. The method of claim 1, 2, 4, 6, 7 or 8,

where a constant shorter pulse length is used.

10. The method of claim 1, 7, 8 or 9,

where only two different pulse lengths are used.

11. The method according to claim 1, 3, 5, 6 or 7,

in which, at the longer pulse durations, the at least one energy beam (22, 22 ', 22' ') is not moved over the surface of the component (1, 120, 130, 155).

12. The method according to claim 1,

in which only one laser (19), in particular with a wavelength, in particular of 1064 nm, is used.

13. The method according to claim 1,

in which two or more lasers (19 ', 19'') are used to produce the hole (7).

14. The method according to claim 13,

in which the same wavelength, in particular 1064 nm or 532 nm, is used for the lasers (19 ', 19 ").

15. The method according to claim 13,

in which different wavelengths, in particular 1064 nm and 532 nm, are used for the lasers (19 ', 19' ').

16. The method according to claim 13, 14 or 15,

wherein the lasers (19 ', 19' ') are adapted to generate equal ranges of pulse lengths.

17. The method according to claim 13, 14 or 15,

wherein the lasers (19 ', 19' ') are adapted to produce different ranges of pulse lengths.

18. The method according to any one of claims 13 to 17,

in which the lasers (19 ', 19' ') are used simultaneously.

19. The method according to any one of claims 13 to 17,

in which the lasers (19 ', 19'') are used consecutively in time.

20. The method according to claim 1, 2, 3 or 9,

in which during the last Abtragungsschritte shorter pulse lengths less than 500ns, in particular less than 100ns, are used.

21. The method according to claim 1, 2, 4 or 9,

in which shorter pulse lengths less than or equal to 500 ns, in particular less than or equal to 100 ns, are used during the first removal steps.

22. The method according to claim 1, 2, 4 to 11 or 21,

wherein an outer top portion (13) of the hole (7) having shorter pulse lengths and then a lower portion (10) of the hole (7) having longer pulse lengths are first generated.

23. Method according to claim 1, 2, 4 to 11 or 21,

wherein an outer edge region (28) having shorter pulse lengths is first generated and then an inner region (25) of the hole (7) having longer pulse lengths is generated.

24. The method of claim 1, 2, 3, 5 to 11 or 21,

in which first an inner region (25) with longer pulse lengths, and then an outer edge region (28) of the hole (7) with shorter pulse lengths is generated.

25. The method according to claim 6,

starting from a surface (14) of the component

(1) the hole (7) is made and in which the pulse length is changed from the outer surface (14) to the depth of the hole (7).

26. The method according to one or more of the preceding claims,

in which a pulse duration of> 0.4ms to 1.2ms is used for the longer pulses.

27. Method according to one or more of the preceding claims,

in which the longer pulses have an energy of 6 to 21 joules, in particular 8 joules.

28. Method according to one or more of the preceding claims,

in which the longer pulses have a power of 10 to 50 kilowatts, in particular 20 kilowatts.

29. The method according to any one of claims 1, 2, 4, 6, 7, 9, 20 to 24,

in which the energy of the shorter pulses is at or below the two-digit, in particular in the single-digit Millij oule range (mJ)

30. The method according to any one of claims 1, 2, 4, 6, 7, 9, 20 to 24,

in which the shorter pulses have a power in the single-digit kilowatt range.

31. The method according to any one of claims 1, 3, 5 - 11, 22 - 28,

in which the longer pulses produce the cross-sectional area (A) of the ablated region on the component (1) corresponding to the cross-sectional area of the hole (7, 10) to be produced.

32. The method according to one or more of the preceding claims,

wherein, when using longer or shorter pulses (16), an output power of the laser (19, 19 ', 19'') is constant as long as the pulse length does not change for the longer or shorter pulses.

33. The method according to one or more of the preceding claims,

in which for the longer pulses an output power of the laser (19, 19 ', 19' ') of several 100 watts, in particular of 500 watts is used.

34. The method according to one or more of the preceding claims,

wherein at the shorter pulses an output power of the laser (19, 19 ', 19' ') is less than 300 watts.

35. The method according to claim 1,

in which with the method a component (1) is processed, which represents a layer system.

36. The method according to claim 35,

in which the method processes a layer system (1) which consists of a metallic substrate (4) and at least one ceramic layer (16 '').

37. The method according to claim 35 or 36,

in which the layer system (1) consists of a substrate (4) and a metallic layer (16 ') which in particular has a composition of the type MCrAlX, where M represents at least one element of the group iron, cobalt or nickel, and X represents Yttrium and / or at least one element of the rare earths stands.

38. The method according to claim 35, 36 or 37,

in which the layer system (1) consists of a substrate (4) and a layer (16) which has a metallic intermediate layer (16 ') and an outer ceramic layer (16' ').

39. The method of claim 36, 37 or 38,

wherein the substrate (4) is a nickel, cobalt or iron based superalloy.

40. The method according to claim 35,

in which the method processes a component (1) which is a turbine blade (120, 130), a heat shield element (155) or another construction or housing part (138) of a gas (100) or steam turbine.

41. The method according to claim 1 or 40,

in which the method is used in the new manufacture of a component (1, 120, 130, 155).

42. The method according to claim 1 or 40,

in which the method is used in a reworking component (1, 120, 130, 155).