This application is the US National Stage of International Application No. PCT/EP2016/076361 filed Nov. 2, 2016, and claims the benefit thereof. The International Application claims the benefit of German Application No. DE 102015223576.9 filed Nov. 27, 2015. All of the applications are incorporated by reference herein in their entirety.
The invention relates to a thermal barrier coating system with a thermal barrier coating, a two-layer thermal barrier coating being applied locally in a highly stressed region.
Ceramic thermal barrier coatings (TBC) are used to protect components for use at high temperatures from heat input. This is the case with turbine blades. For example, EP 2 845 924 A1 discloses using coating systems comprising a first ceramic layer of fully or partly stabilized zirconia and on it a layer that has a pyrochlore structure, such as gadolinium zirconate.
Because of greater thermal stresses in the case of turbine blades of a turbine, there are local temperature peaks in the pressure region of the turbine blade. This leads to greater consumption of the metallic protective layer or to spalling of the TBC. The use of cooling air holes would lead to the consumption of compressor air, and consequently to a reduction of efficiency.
Without countermeasures, the maximum running time of the turbine would be reduced.
An object of the invention is therefore to solve the aforementioned problem.
The object is achieved by a coating system according to the claims.
In the figures
The figures and the description only show exemplary embodiments of the invention.
There is a suction side 7 and a pressure side 4, the turbine blade 1 being subjected to a flow of hot gas at an inflow edge 10 and having an outflow edge 13.
In the case of the turbine blade 1, there is a highly stressed region 22 in the region of the pressure side 4.
The turbine blade 1 is flowed around by a hot gas in the direction of flow 11.
In a local region 22, there is increased thermal stress. In this region there is a local reinforcement 36, 36′, 36″ (
The local reinforcement 36, 36′, 36″ is advantageously arranged close to a platform 21 and advantageously can extend with a transitional region 39 (
Perpendicularly or in a radial direction thereto, that is to say in the direction 40, the extent is a maximum of 50%, in particular at most 30%. In the case of a turbine blade 1, this figure advantageously relates only to the blade airfoil 19.
In order to allow for this increased thermal stress, the thickness of the thermal barrier coating is increased locally.
The increase in the layer thickness does not take place as a result of increased application of the same material of the surrounding layer 33, but instead a second material, different from the first material, is applied locally.
The first ceramic layer 33 is arranged on the blade airfoil 19 and the blade platform 21 of a turbine blade 1.
Advantageously, the thermal barrier coating 33 on the turbine blade 1 is a zirconium-based layer, in particular a layer of partly stabilized zirconia, and the reinforced TBC is achieved by local application of a pyrochlore layer 36, 36′, 36″, in particular based on gadolinium zirconate.
The material of the local reinforcement 36, 36′, 36″ is advantageously also fully stabilized zirconia.
The material of the local reinforcement 36, 36′, 36″ is advantageously made to be at least 10%, in particular 20%, more porous than the first ceramic layer 33.
In particular, like the first ceramic layer 33, it 36, 36′, 36″ likewise comprises partly stabilized zirconia.
In this case, as shown in
Similarly, it is possible to make the underlying thermal barrier coating 33 somewhat thinner in the region of the local reinforcement 36″, so that there is a recess 34, in which the other material is applied locally, to be precise is applied in such a way that a thickening is obtained (
The first ceramic layer 33 advantageously has a thickness of 350 μm-500 μm.
The local reinforcement 36, 36′, 36″ advantageously has a thickness of up to 300 μm, in particular up to 250 μm.
Advantageously, the local reinforcement 36, 36′, 36″ is at least 10%, in particular at least 30%, thinner than the first ceramic layer 33.
Between the region that has only the first thermal barrier coating 33 and the local reinforcement 36, 36′, 36″ (
The transitional region 39 likewise represents a local area.
Number | Date | Country | Kind |
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10 2015 223 576 | Nov 2015 | DE | national |
Filing Document | Filing Date | Country | Kind |
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PCT/EP2016/076361 | 11/2/2016 | WO | 00 |
Publishing Document | Publishing Date | Country | Kind |
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WO2017/089082 | 6/1/2017 | WO | A |
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20180334914 A1 | Nov 2018 | US |