Layer system and process for its production

p0001The invention relates to a layer system according to the preamble of claim 1 and method for producing a layer system according to the preamble of claims 11 and 12. FIG.

p0002Components for high temperatures today are generally provided with protective layers. These may be metallic corrosion protection layers (MCrAlX layers) or ceramic thermal barrier coatings and coating systems with metallic corrosion protection coatings and ceramic thermal barrier coatings. As a coating method for these coatings to use plasma-based powder spraying process because of their relatively high efficiency. The connection of such layers to the substrate is carried out by mechanical clamping and subsequent diffusion heat treatment. Occasionally it can in high stress areas or unfavorable, that occur particularly at high mechanical stress points of the component to a detachment of the layer in operation. The flaking of the layer during the operation leading to the damage of the base material so that the component life is substantially reduced.

p0003EP 1275748 A2 discloses a layer system in which anchoring means are provided on a substrate, which extend through multiple layers. An outer ceramic layer is not present.

p0004The DE 30 38 416 A1, discloses a layer system in which anchoring means are part of the substrate and said anchoring means all form part of the outer surface. Also, a part of the intermediate layer on the surface is present.

p0005It is therefore an object of the invention to provide a layer system and method for producing a layer system, which has a better bonding of a protective layer on a substrate and / or layers to one another.

p0006The object is achieved by a layer system according to of claim 1 and by processes for producing a layer system according to the claims 11 and 12. FIG.

p0007The layer system according to the invention has separately on anchoring means formed, which have a very strong bonding to the substrate or to a lower her disposed on the substrate layer and are connected in another way than the layer on the substrate or other layer. The anchoring means extending only within the interlayer. Likewise, the material of the anchoring means corresponds to the material of the layer. An outer ceramic layer is present and is disposed over at least one anchoring means of the interlayer.

p0008The compared to the existing layer bonding (eg clamping by surface roughness) a stronger link between the anchoring means for example by a melt metallurgical bond that is produced in a separate process. Thus can still be used, the inexpensive and economical plasma spray process to deposit the layer.

p0009The subclaims list further advantageous measures are listed. The measures listed in the dependent claims may be combined in an advantageous manner.

p0010Show it<dl id="dl0001" compact="compact"><dt>figure 1</dt><dd>a layer system according to the prior art,</dd><dt>figure 2</dt><dd>Part of an inventively embodied layer system,</dd><dt>figure 3</dt><dd>a perspective plan view of an invention designed according to the layer system,</dd><dt>figure 4</dt><dd>The method steps of a method according to the invention,</dd><dt>figure 5</dt><dd>Method steps of another method according to the invention,</dd><dt>6, 7</dt><dd>inventively constructed layer systems,</dd><dt>figure 8</dt><dd>a gas turbine and</dd><dt>figure 9</dt><dd>a combustion chamber.</dd></dl>

p00111 shows a layer system according to the prior art. The layer system comprises a substrate 4th The substrate 4 may be metallic or ceramic, and in the case of gas turbine components in particular from an iron-, nickel- or cobalt-based super alloy.

p0012On the substrate 4 is a layer 7, 9 (in Fig. 6, 7, two layers) are present. This is a metallic layer and a ceramic layer 7 9th

p0013For turbine blades 120, 130 (Fig. 8), for example, on the substrate 4, a metallic corrosion-protection layer of the MCrAlX type 7 (8 Fig. 6, 7) is applied, after which additionally has an outer, for example, a ceramic thermal barrier layer 9 (Fig. 6 , 7) is applied.

p0014The connection of the intermediate layer 7 on the substrate 4 or the layers 7, 9 to each other is carried out according to the prior art solely by mechanical interlocking (surface roughness) on the underlying surface, and subsequent diffusion heat treatment.

p00152 shows from Figure 1, an intermediate layer 7 of a layer system according to the invention 1 (FIG. 6, 7). On the surface 5 of the substrate 4 anchoring means 10, 13 are present. The anchoring means 10, 13 have some kind of connection to the surface 5, an increased connection strength (more precisely, force / per contact surface) with respect to the type of connection of the intermediate layer 7 arises on the surface 5 to the surface. 5

p0016The anchoring means 10, 13 are connected for example by a suitably guided laser welding process by melt metallurgy to the substrate. 4 It is also conceivable that the layer 7 is applied at certain points by laser cladding (Laser powder coating), thus forming anchoring means 10, the thirteenth The anchoring means 10, 13 can also be molded or produced with the casting of the substrate. 4 The anchoring means 10, 13 provide adhesion bridges are for the anchoring means 10, 13 surrounding layer 7. 9 The anchoring means 10 may extend from the surface 5 of the substrate 4 extend to the outer surface 8 of the intermediate layer 7, or they are covered by the layer 7, 13, so that the anchoring means 13 do not extend up to the surface 8 of the layer 7, ie within the layer 7, 9 are arranged ending. They extend up to 13, at least 10%, 20%, 30%, 40% of the thickness of the layer 7, 9 in the layer 7 9th

p0017The anchoring means 10, 13 are, for example, only locally, that locally limited (Fig. 3) on the substrate 4 or the layer 7 exists, namely, where the mechanical stress is greatest.

p0018This is for example the area of ​​the leading edge of a turbine blade or vane 120, 130. The rest of the airfoil would then have no anchoring means.

p0019Figure 3 shows a plan view of a surface layer 8 of a seventh indicated by dashed lines are the anchoring means 13 that do not extend to the surface 8 of the layer. 7 The anchoring means 10, 13 may on the surface 5 different geometries such as circles, topstitching (ie they are elongate and intersect), waveforms parallel runways and combinations thereof.

p0020Figure 6 shows an inventively constituted coating system. 1 The layer system 1 comprises a substrate 4 and two layers 7, 9th The intermediate layer 7 is, for example, a metallic MCrAIX layer and the outer layer 9 is a ceramic thermal insulation layer 9 on the intermediate metal layer. 7

p0021Anchoring means 10, 13 are present in both the intermediate layer 7 as well as in the outer layer. 9

p0022Similarly, the anchoring means may be present (Fig. 7) only in the intermediate layer 7.

p0023The anchoring means 10, 13 in the layers 7, 9 may be prepared starting from the surface 5, 8 of the substrate 4 or the intermediate layer 7 to the outer surface 8, 16 of the layer 7, 9 extend or through the layers 7, 9 covered, so that the anchoring means 13 are not, 9 extend up to the surface 8, 16 the layers 7th

p0024The anchoring means 10, 13 in the intermediate layer 7 improve the connection of the intermediate layer 7 to the substrate. 4

p0025The anchoring means 10, 13 are present in particular in thermally and / or mechanically highly stressed areas.

p0026The layer system 1 is, for example, a component of a gas-100 (Fig. 8) (also aircraft turbine) or steam turbine. Thermally highly stressed components of the turbines have such a layer system, such as turbine blades 120, 130, 155 liners a combustion chamber 110 and other housing parts located along the flow path of hot steam or hot gas itself.

p0027The layer system 1 may be applied to a newly manufactured component as well as components that are reprocessed after use (refurbishment). The components are first removed from degraded layers, optionally repaired cracks and there is a new coating of the substrate. 4

p00287 shows a further exemplary embodiment of a layer system according to the invention. 1 In this coating system 1, the anchoring means 10, 13 only in the intermediate layer 7 is present. On the intermediate layer 7, the outer layer 9 is present. A contact surface of the anchoring means 10 at the surface 8 improves the adhesion of the outer layer 9 with respect to a similar contact surface with the intermediate layer 7. This is for example achieved by the fact that the contact surfaces of the anchoring means 10 form 8 nucleation points on the surface for example, epitaxial growth of an outer layer 9 on the interlayer 7th Even without intermediate layer 7 (Fig. 4, 5, right side) is an improved coating system 1 achieved in that the anchoring means 10, 13 lead to improved bonding of the outer layer 9 on the substrate 4.

p0029Figure 4 shows an example of process steps of a method for producing a layer system. 1 In a first step, the at least one layer 7, 9 applied to the substrate 4 or to an already present on the substrate layer in a known manner.

p0030The layer 7, 9 is treated with a laser 16 or an electron beam gun 16 which emits a corresponding laser beam or electron 19th Through this type of treatment, the material of the layer 7, 9 to the surface 5, 8 of the substrate 4 or the interlayer 7 is converted back locally, melted, for example, so that a melt-metallurgical bonding material from the layer 7, 9 of the 4 substrate or already on layer is generated. With this method, anchoring means 10 are generated which extend from the surface 5, 8 to surface 8, 16 of the layer 7 9th

p0031The anchoring means 10 are formed, for example, columnar and may also be designed curved concave or convex (Fig. 7).

p0032Figure 5 shows an example of steps of a method according to the invention. In a first step, the anchoring means 10, 13 are applied to the substrate 4 or the layer 7 first, so produced separately. This can be done in various ways, such as by a suitably guided laser welding process or laser cladding. The anchoring means 10, 13 have a very strong, in particular melt-metallurgy attachment to the surface 5, 8 of the substrate 4 or the interlayer. 7

p0033but the anchoring means 10, 13 may also have been generated in the production of the substrate 4, for example by a casting process.

p0034In a subsequent process, the layer 7, 9 is applied, wherein the anchoring means 10, 13 are enclosed by the material of the layer 7, and 9 represent adhesion bridges for the layer 7 9th

p0035The material of the anchoring means 10, 13 is equal to the material of the layer 7 9th

p00368 shows a gas turbine 100 in a longitudinal partial section. The gas turbine 100 internally comprises a about a rotation axis 102 mounted rotor 103, which is also referred to as the turbine rotor. Along the rotor 103 are an intake manifold 104, a compressor 105, an eg toroidal combustion chamber 110, in particular annular combustion chamber 106, with a plurality of coaxially arranged burners 107, a turbine 108 and the exhaust manifold 109. The ring combustion chamber 106 communicates with an eg annular hot gas channel 111th There, for example, four successive turbine stages 112 form the turbine 108. Each turbine stage 112 is formed from two blade rings. Viewed in the flow direction of a working medium 113, followed by 120 formed from rotor blades 125 series in the hot gas passage 111 a row of guide vanes 115th

p0037The guide vanes 130 are secured to the stator 143 while the rotor blades 120 of a row 125 are fitted by means of a turbine disk 133 rotor 103rd Coupled to the rotor 103 is a generator or a work engine (not shown).

p0038During operation of the gas turbine 100 is the compressor 105 through the intake housing 104 air sucked 135 and compressed. The provided at the turbine-side end of the compressor 105, compressed air is delivered to the burners 107 and mixed there with a fuel. The mixture is then burnt to form the working medium 113 in the combustion chamber 110th From there, the working medium 113 along the hot gas channel 111 flows past the guide vanes 130 and the rotor blades 120. The working medium 113 expands at the rotor blades 120, transferring its momentum, so that the rotor blades 120 drive the rotor 103 and the generator coupled to it working machine.

p0039To the hot working medium 113, the components exposed 100 thermal stresses during operation of the gas turbine. The guide vanes 130 and rotor blades 120 of the flow direction of the working medium 113, the first turbine stage 112, in addition to the annular combustion chamber 106 heat shield bricks which the highest thermal stresses. In order to withstand the temperatures prevailing there, they are cooled by means of a coolant. Similarly, the blades 120, 130 may have coatings against corrosion (MCrAlX; M = Fe, Co, Ni, X = Y, rare earths) and heat (thermal barrier coating, for example ZrO₂, Y₂O₃-ZrO₂) Exhibit.

p0040The guide vane 130 has a the inner housing 138 of the turbine 108 facing vane root (not shown here) and a guide vane head lying opposite the guide vane root. The guide vane head faces the rotor 103 and is fixed to a securing ring 140 of the stator 143.

p00419 shows a combustion chamber 110 of a gas turbine 100. The combustion chamber 110 is configured, for example as a so-called annular combustion chamber, in which a plurality of spaced around the turbine shaft 103 in the circumferential direction burners 102 open into a common combustion chamber space.

p0042For this, the combustion chamber 110 overall is of annular configuration positioned around the turbine shaft 103.

p0043To achieve a relatively high efficiency, the combustion chamber 110 is designed for a relatively high temperature of the working medium M of approximately 1000 ° C to 1600 ° C. To enable even under these unfavorable for the materials operating parameters a comparatively long operating time, the combustion chamber wall 153 is provided on its the working medium M-facing side with an inner lining formed from heat shield elements 155th Each heat shield element 155 is been fitted with a particularly heat-resistant protective layer or is made from high temperature resistant material. Due to the high temperatures inside the combustion chamber 110, a cooling system is also provided for the heat shield elements 155 or for their holding elements.