EP2528693A1 - Spray nozzle and method for atmospheric spraying, device for coating, and coated component - Google Patents

Abstract

By means of a plasma spray nozzle that enables atmospheric plasma spraying using protective gas, it is also possible to deposit oxidation-sensitive metal coatings in atmosphere.

Description

 SPRAY NOZZLE AND METHOD FOR ATMOSPHERIC SPRAYING, COATING AND COATED COMPONENT DEVICE

The invention relates to a method for atmospheric

Plasma spraying, a coating device and a component.

Atmospheric plasma spraying is an economical alternative of plasma spraying, there can be dispensed with here a vacuum ^¬ system. However, this is not possible with each ^¬ the powder. In other coating methods, certain properties of the metallic layer are often not achieved.

In order to increase the efficiency of a turbine, the turbine inlet temperature of the gas must be increased. So that the turbine blades are not damaged at these high temperatures of> 800 ° C, a metallic coating is applied as oxidation protection and adhesion promoter layer (HVS) and then a ceramic coating for thermal insulation. Keeping the ceramic coating on the HVS requires a very rough surface. Currently, this HVS is usually applied with vacuum technology spray technology, which are very complex and expensive. Furthermore, they lack the flexibility to use other coating materials than MCrAlY for HVS. For these reasons, it is currently being started to replace the vacuum methods with others. One of these methods is high velocity flame spraying (HVOF). Producing the required rough coating with a HVOF process is technologically quite difficult. Especially with flat coating angles, ie <90 ° to the surface, a sufficiently rough surface can not be created. A coating by means of atmospheric plasma spraying is not possible because the MCrAlY alloy oxidizes under the action of atmospheric oxygen. It is therefore an object of the invention to solve the above-mentioned problem.

The object is achieved by a plasma spray nozzle according to claim 1, by a method according to claim 10, 13, by a device according to claim 15 and a component according to claim 17 An ^¬ .

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

1 shows an attachment for a plasma spray nozzle,

 2, 3 different attachments for the plasma spraying nozzle, FIG. 4 in perspective a gas turbine,

 FIG. 5 shows in perspective a turbine blade,

 FIG. 6 shows in perspective a combustion chamber,

Figure 7 is a list of superalloys.

The description and the figures represent only embodiments of the invention.

In the figure 1, a spray nozzle 1 is shown.

 The spray nozzle 1 has a conventional nozzle 4 known from the prior art for plasma spray nozzles (APS, ...) and an attachment 19. Parallel to a longitudinal direction 26 of an inner channel 22 of the nozzle 4 flows through a plasma heated, at least partially melted coating material from the nozzle 4 in a discharge direction 25. The plasma is generated in the inner channel 22 of the nozzle 4.

The nozzle 4 is only modified so that an attachment 19 can be attached to it. The top 19 extends the inner channel of the nozzle 4. Through holes 13, 13 ', 13''on the end face 31 of the cap 19, which are preferably nozzle-shaped, (see also Fig. 2, 3) flows a protective gas 28 and generates a desired geometry of a

Protective gas mantle around the outflowing coating material. The shielding gas 28 can also ausströ ^¬ slits 14 ', 14''men, which are arranged in a circle (Fig. 3). At least two, in particular four slots 14 ', 14'', ... are preferential ^¬ be present.

The shielding gas 28 may preferably be argon, helium, nitrogen or a mixture thereof.

The holes 13, 13 ', 13'', ... and / or slots 14', 14 '', ... are aligned in the longitudinal direction 26 so that the protective gas 28 flows out in an outflow direction 25, wherein the out ^¬ flow direction 25 runs parallel to the longitudinal direction 26.

The attachment 19 on the nozzle 4 has on its end face 31 preferably circularly arranged holes 13 ', 13' '(FIG. 2). The holes 13 ', 13' ', ... and / or the slots 14', 14 '', ... are preferably evenly distributed in the radial circumferential direction on the end face 31.

Preferably, a portion of the protective gas 28 also flows through at least one opening 16 in the proportion of the inner channel 22 of the attachment 19. This serves to cool the attachment 19th

A powder feed 7 is also present and preferably arranged in front of the attachment 19.

The powder feed 7 can also be present at any other point of the nozzle 4.

The attachment 19 preferably has an outer solid shell, so that only a few discrete holes 13, 13 ', ... or slots 14', 14 '', ... are present. Similarly, the extension of the channel 22 in the area of the essay by a solid inner shell of the essay

educated .

 The attachment 19 is preferably not made of a porous solid material.

In a corresponding coating device, a coating can be carried out by means of the HVOF process, which is inexpensive. However, in order to coat certain roughnesses or at an angle of up to 45 ° to the coating surface, an APS nozzle (atmospheric plasma ^¬ squirt) must be used, which has a corresponding attachment 19 according to FIG. Both coating options HVOF, APS are now preferably realized in one device.

On an existing coating, which was applied by means of a HVOF Pro ^¬ zesses, a rougher coating is applied with an APS torch. After the HVOF coating, the HVOF nozzle is dismantled and an APS nozzle 1 installed in the same device.

In this case, an attachment 19 is mounted on an APS burner (nozzle 4). By this essay 19 is a protective gas 28, such. As nitrogen, passed. This also simultaneously cools the attachment 19. Through the interior of the attachment 19 flows through the plasma heated, preferably metallic coating material. Also, the entire layer can be made with the article 19.

The coating material is melted in the plasma jet at least ^¬ and applied to a substrate. The protective gas 28 is conducted in such a way through the attachment 19, that after the exit of the molten particles from the

Spray nozzle 1 forms a protective gas sheath around the particle beam. This is particularly important for metallic coating material, which would oxidize too much in plasma spraying, but not so strong in HVOF.

This coating prevents oxidation of the particles. Since the particle velocity in the APS is much lower than in the HVOF, the particles adhere better to the substrate surface. This makes it possible to coat at an angle of up to 45 ° to the surface. The greater roughness compared to HVOF is always present in this process.

 Due to the design of the attachment 19, the protective gas jacket can be influenced. Different geometries and arrangements of the exit holes 13, 13 ', 13' 'or slots 14',

14 '', 14, ... in turn influence the design and the geometry of the protective gas mantle.

For the most varied applications, only the attachment 19 must be exchanged. It is thus possible to test and evaluate with a nozzle 4 ver ^{¬ most different} attachment configurations 19 and thus protective gas jacket configuration. If the protective gas mantle must be more or less twisted due to the application, only the geometry of the protective gas outlet holes is adjusted.

For turbine blades 120, 130 with a complicated geometry and poor accessibility to the areas to be coated, this type of coating is a good and simple solution. Expensive low-pressure and vacuum systems become superfluous because the same systems can be used as with the thermal insulation coating. The resulting

Layers have much higher roughness and better layer morphology at hard-to-reach locations compared to HVOF sprayed layers. Due to the variability of the easily replaceable attachment 19 each application can be covered. The main body 4 remains on Plasma torch, which eliminates a complex assembly and disassembly.

FIG. 4 shows by way of example a gas turbine 100 in a longitudinal partial section.

The gas turbine 100 has a rotatably mounted about a rotational axis 102 ^¬ rotor 103 with a shaft, which is also referred to as the turbine rotor.

Along the rotor 103 follow one another an intake housing 104, a compressor 105, for example, a toroidal combustion chamber 110, in particular annular combustion chamber, with a plurality of coaxially arranged burners 107, a turbine 108 and the exhaust housing 109th

The annular combustion chamber 110 communicates with an annular annular hot gas channel 111, for example. There, for example, four turbine stages 112 connected in series form the turbine 108.

 Each turbine stage 112 is formed, for example, from two blade rings. In the flow direction of a working medium

As can be seen in the hot gas duct 111 of a guide blade row 115, a row 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 100 104 air 135 is sucked by the compressor 105 through the intake housing and ver ^¬ seals. The 105 ^¬ be compressed air provided at the turbine end of the compressor 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 blades 120. On the blades 120, the working medium 113 expands in a pulse-transmitting manner, so that the blades 120 drive the rotor 103 and this drives the working 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 a 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.

The guide vane 130 has an inner housing 138 of the turbine 108 facing guide vane root (not Darge here provides ^¬) and a side opposite the guide-blade root vane root. The vane head faces the rotor 103 and fixed to a mounting ring 140 of the stator 143.

FIG. 5 shows a perspective view of a rotor blade or guide vane 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 to each other, a securing region 400, an adjoining blade or vane platform 403 and a blade 406 and a blade tip 415.

As a guide vane 130, the vane 130 may be pointed on its shovel 415 have a further platform (not Darge ^¬ asserted).

In the mounting region 400, a blade root 183 is formed, which serves for attachment of the blades 120, 130 to a shaft or a disc (not shown).

The blade root 183 is, for example, as a hammerhead out staltet ^¬. Other designs as Christmas tree or Schwalbenschwanzfuß are possible.

The blade 120, 130 has a medium felblatt to the Schau- 406 flows past, a leading edge 409 and a ^trailing edge 412th

In conventional blades 120, 130, in all regions 400, 403, 406 of the blade 120, 130, for example, massive metallic materials, in particular superalloys, are used.

 Such superalloys are known, for example, from EP 1 204 776 B1, EP 1 306 454, EP 1 319 729 A1, WO 99/67435 or WO 00/44949.

The blade 120, 130 can be made by a casting process, also by directional solidification, by a forging process, by a milling process or combinations thereof. Workpieces with a monocrystalline structure or structures are used as components for machines which are exposed to high mechanical, thermal and / or chemical stresses during operation. The production of such monocrystalline workpieces, 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, for general language use, referred to as directionally solidified) or a monocrystalline structure, ie the entire workpiece ^¬ is of a single crystal. In these methods, you have to transition to globular (polycrystalline) solidification avoided, since non-directional growth inevitably forms transverse and longitudinal grain boundaries ^¬ which solidified the directionally the good qualities or monocrystalline component nullify.

Is generally speaking of directionally solidified structures speech, so are both single crystals meant that have no grain boundaries or at most small angle grain boundaries, as well

Stem-crystal structures, which probably have longitudinally extending grain boundaries, but no transverse grain boundaries. These second-mentioned crystalline structures are also known as directionally solidified structures.

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

Likewise, the blades 120, 130 may have coatings against corrosion or oxidation, e.g. B. (MCrAlX, M is at least one element of the group iron (Fe), cobalt (Co),

Nickel (Ni), X is an active element and stands for yttrium (Y) and / or silicon and / or at least one element of the rare earths, or hafnium (Hf)). Such alloys are known from EP 0 486 489 B1, EP 0 786 017 B1, EP 0 412 397 B1 or EP 1 306 454 A1.

 The density is preferably 95% of the theoretical

Density. A protective aluminum oxide layer (TGO = thermal grown oxide layer) is formed on the MCrAlX layer (as an intermediate layer or as the outermost layer). Preferably, the layer composition comprises Co-30Ni-28Cr-8A1-0, 6Y-0, 7Si or Co-28Ni-24Cr-10Al-0, 6Y. Besides these cobalt-based protective coatings, nickel-based protective layers such as Ni-10Cr-12Al-0.6Y-3Re or Ni-12Co-21Cr-IIAl-O, 4Y-2Re or Ni-25Co-17Cr-10A1-0, 4Y-1 are also preferably used , 5Re.

On the MCrAlX may still be present a thermal barrier coating, which is preferably the outermost layer, and consists for example of Zr0 ₂ , Y2Ü3-Zr02, ie it is not, partially 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, for example atmospheric plasma spraying (APS), LPPS, VPS or CVD. The heat insulation layer may have ^¬ porous, micro- or macro-cracked ^compatible 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 also has, if necessary, film cooling holes 418 ^(indicated by dashed lines) on.

Figure 6 shows a combustion chamber 110 of the gas turbine 100. The combustion chamber 110 is configured, for example as so-called ^an annular ^combustion chamber, in which a plurality of in the circumferential direction about an axis of rotation 102 arranged burners 107 open into a common combustion chamber space 154, create the 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. To even under these unfavorable for the materials operating parameters, a relatively long service life loan to enable the combustion chamber wall 153 is provided on its side facing the ^working medium M facing side with a formed from heat shield elements 155. liner.

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, for example, hollow and possibly still have cooling holes (not shown) which open into the combustion chamber space 154.

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. On the MCrAlX an example, ceramic Wär ^¬ medämmschicht may be present and consists for example of ZrO 2, Y203 ^~ Zr02, ie it is not, partially or vollsten- 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, for example atmospheric plasma spraying (APS), LPPS, VPS or CVD. The heat insulation layer may have ^¬ porous, micro- or macro-cracked ^compatible grains for better thermal shock resistance.

Reprocessing (Refurbishment) means that turbines ^¬ blades 120, 130, heat shield elements have to be removed from 155, after ^¬ A set of protective layers (for example 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. 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 1. Spray nozzle (1) for atmospheric plasma spraying, from which (1) emerges in an outflow direction (25) coating material,  in which a nozzle (4) has an attachment (19) at one axial end,  from the (19) in the outflow direction (25) a protective gas (28) can escape. 2. Spray nozzle according to claim 1,  in which the attachment (19) for the nozzle (4) can be varied. 3. Spray nozzle according to claim 1 or 2,  in which the attachment (19) has on its end face (31) a plurality of outlet holes (13, 13 ', 13' ',...) for the protective gas (28). 4. Spray nozzle according to claim 1, 2 or 3, wherein said the attachment (19) on its end face (31) meh ^¬ eral slots (14 ', 14'',14''', ...) for the protective gas (28). 5. Spray nozzle according to claim 1, 2, 3, 4,  in which at the nozzle (4) or on the attachment (19) a powder feed (7),  especially before the article (19), is available. 6. Spray nozzle according to claim 1, 2, 3, 4 or 5, wherein a portion of the protective gas (28) through an inner opening (10) in an inner channel (22) of the attachment (19) can flow. 7. Spray nozzle according to claim 1, 2, 3, 4, 5 or 6,  in which the holes (13, 13 ', ...) or the slots (14', 14 '', ...) for the protective gas (28) are nozzle-shaped. 8. Spray nozzle according to claim 1, 2, 3, 4, 5, 6 or 7,  wherein the holes (13, 13 ', ...) or the slots (14) in the radial circumferential direction on the end face (31)  evenly distributed. 9. Spray nozzle according to one or more of claims 1 to 8,  in which the spray nozzle (19) has a solid outer and / or inner shell. 10. Method for coating a component (120, 130, 155),  in which a spray nozzle (1) according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9 is used. 11. The method according to claim 10,  in which a protective gas (28) during atmospheric spraying flows out of holes (13, 13 ', 13' ', ...) or slots (14', 14 '', ...), that (28) forms a gaseous protective jacket around an outflowing coating material. 12. The method according to claim 10 or 11,  in which first a nozzle (4) without attachment (19) and then a nozzle (4) with the attachment (19)  is used. 13. Method for coating a component (120, 130,  155),  in which first a HVOF coating takes place and  then a plasma coating,  in particular by means of APS, more in particular by means of a spray nozzle (1) according to claim 1. ^¬, 2, 3, 4, 5, 6, 7, 8 or 9 or a method according to claim 10, 11 or 12,  which takes place in the same coating device. 14. The method according to claim 10, 11, 12 or 13,  in which metallic powder is sprayed. 15. Apparatus for coating a component (120, 130, 155),  which has:  a holder for the component (120, 130, 155),  a component (120, 130, 155),  a robot,  which can move a spray nozzle (1) according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9. 16. Device according to claim 12,  the one HVOF nozzle and  a nozzle for atmospheric spraying,  in particular a spray nozzle (1) according to claim 1, 2, 3, 4, 5, 6, 7, 8 or 9, can record. 17. component (120, 130),  in particular produced according to claim 10, 11, 12, 13 or 14,  which has an HVOF layer and a plasma-sprayed layer on the HVOF layer.