Partial recoating of ceramic layer systems and ceramic layer systems

Abstract

The present invention relates to a method for partial recoating of a ceramic layer system (1), wherein a recess (16) is first created in the ceramic layer system (1) by means of a coating removal method, wherein the ceramic coating is partially and completely removed and the metal coating is partially and at least partially removed, wherein a metal adsorbent layer (7) is then applied, wherein a protective portion (19) is preferably used around the recess (16), and after the metal adsorbent layer (7') is fully applied or repaired, material is removed obliquely in the edge region within the recess (16) in such a way as to remove the material of the ceramic layer (10) in a stepped manner around the recess (16), and then, in a final step, new ceramic material (31) is applied to the repaired recess (16').

Description

Technical Field

[0001] This invention relates to partial recoating of ceramic layer systems and ceramic layer systems. Background Technology

[0002] Ceramic layer systems with a metal matrix having at least one ceramic layer as protection against high temperatures and / or corrosion are known and used in the chemical industry, furnaces, and turbines, especially gas turbines.

[0003] An exemplary ceramic layer is disclosed in document EP 1 707 653 B1.

[0004] Due to wear caused by use, sometimes only localized damage to the ceramic layer occurs.

[0005] The existing practice is to completely treat and recoat the component. This is especially problematic for layer systems consisting of a metal underlayer and a ceramic top layer, as completely removing the metal and ceramic layers and recoating is extremely cumbersome.

[0006] The metal and ceramic layers are applied by spraying.

[0007] Document US 6,274,193 B1 discloses a repair method in which the metal coating is diffused into the metal. Summary of the Invention

[0008] Therefore, the purpose of this invention is to solve the above-mentioned problems.

[0009] This objective is achieved by the method according to claim 1 and the ceramic layer system according to claim 4.

[0010] Other advantageous measures are listed in the dependent claims, which can be combined with each other in any way to achieve additional advantages. Attached Figure Description

[0011] Figure 1 , Figure 6 A ceramic layer system is shown, and in Figures 2 to 5 The method is illustrated schematically in the diagram. Detailed Implementation

[0012] exist Figure 1The ceramic layer system 1 is schematically shown. This ceramic layer system 1 has at least one component: a metal matrix 4, which, for turbine components, is a nickel-based superalloy or a cobalt-based superalloy. Due to the difference in thermal expansion coefficients between the metal and the ceramic, a metal adsorbent layer 7 is present for better bonding. This metal adsorbent layer, during use, forms an oxide layer (TGO) for bonding the ceramic layer 10. Preferably, the metal adsorbent layer 7 is based on a NiCoCrAlY alloy. Preferably, the metal adsorbent layer 7 is a coating layer, i.e., not a simple diffusion layer.

[0013] The ceramic layer 10 can be constructed as a single layer or a double layer, that is, in a double-layer system, different materials are used. An example of this is a ceramic layer at the bottom composed of partially stabilized zirconia PSZ (such as 7YSZ) and a ceramic layer at the top composed of fully stabilized zirconia FSZ (such as 20YSZ).

[0014] Due to wear, the layer thickness of TBC has been locally reduced or has disappeared (not shown).

[0015] Therefore, by means of a coating removal method, especially by means of laser 13, the ceramic layer 10 is locally removed. Figure 2 ).

[0016] Also preferably, the metal adsorbent layer 7 is partially removed. Figure 2 ).

[0017] Water jet removal, including or without abrasive materials, or other methods (such as laser irradiation or a laser beam guided in a water jet) can also be used.

[0018] Preferably, the material of matrix 4 is not removed at this time.

[0019] Local removal based on Figure 1 After the ceramic layer 10, the ceramic layer system 1' subsequently has a recess 16.

[0020] In the next step ( Figure 3 The metal adhesive layer is locally re-established in the recess 16 by the coating system 22, thereby forming a repaired metal adhesive layer 7'. At this time, the same material as in the original layer system 1 can be used, but this is not necessary.

[0021] If necessary, the matrix 4 material removed in the recess 16 can also be compensated by a metal adhesive layer.

[0022] During the metal coating process, the remaining surface of the ceramic layer system 1' is at least partially provided with a protective portion 19. Figure 3However, a protective layer is provided at least around the recess 16. But this cannot completely prevent the deposition of metal from the metal coating material around the edge region of the recess 16. In any case, there is metal material that needs to be removed on the side 17 of the recess 16 where the remaining ceramic layer 10' is located.

[0023] Subsequently, according to Figure 4 Remove the protective portion 19, and in the next step, remove the existing ceramic of the ceramic layer 10' of the ceramic layer system 1'' in a wedge-shaped or stepped manner around the recess 16, so that there is no longer any metal material on the existing ceramic coating portion 10''' of the ceramic layer system 1'''.

[0024] In the final step, ceramic material 31 is applied to the trimmed recess 16' using another or the same coating system 22, so that the resulting ceramic layer system 11 is identical to the original ceramic layer system 1. Figure 1 )quite.

[0025] The area 34 of the ceramic coating portion filling the recess 16' can be made using the same material from these materials, or different materials can be intentionally used to improve the ceramic layer system 1. IV The use of different materials here means that at least one component of the ceramic has a difference of at least 5%, especially at least 10%, more precisely, that different stabilizers or additional stabilizers are used for the stabilization of zirconia.

[0026] Preferably, the ceramic layer 11 has segmented coating portions, for example, composed of PSZ / FSZ (such as 8YSZ or 8YSZ / 20YSZ). Figure 5 ).

[0027] Preferably, a different microstructure (such as, in particular, a high-porosity material 34') is then applied to the ceramic layer portion 34' in the recess 16' instead of a segmented microstructure. Figure 6 The material 34' in the recess 16' preferably has a porosity greater than 12%, especially greater than 18%, and its porosity is in any way 5% greater than that of the surrounding layer regions 10L, 10R, and absolutely 10% greater. Figure 6 ).

[0028] Preferably, the ceramic layer 10 is a segmented layer composed of yttrium oxide-stabilized zirconium oxide, and the layer portion 34' preferably has yttrium oxide and additionally has ytterbium oxide-stabilized zirconium oxide.

[0029] Similarly, the ceramic layers may have different thicknesses along the extension direction 12 of the ceramic layer system 11, thus using different thicknesses for region 34', in which, for example, a continuous transition is created from a layer thickness 10L to a thinner layer thickness 10R, or as... Figure 6 As shown, the layer thickness is preferably stepped in the middle between two different layer thickness regions 10L and 10R. Thinner generally means that the layer thickness is designed to be at least 5% thicker or thinner, especially at least 10%.

Claims

1. A method for locally recoating a ceramic layer system (1), in, First, a recess (16) is created in the ceramic layer system (1) using a coating removal method. Specifically, at least the ceramic coating is partially and completely removed, and optionally, at least partially, the metal coating is partially removed. Optionally, a metal adhesion layer (7) may then be applied locally. Preferably, a protective portion (19) is used on the surface of the ceramic layer (1') at least around the recess (16). And after the metal adhesive layer (7') has been fully applied or repaired, the material is removed obliquely from the ceramic layer (1'') within the recess (16) in its edge region. The method involves removing the material of the ceramic layer (10'') in a stepped manner around the recess (16). Furthermore, in the final step, new ceramic material (31) is applied to the repaired recess (16').

2. The method according to claim 1, in, The microstructure of layer (11) is generated for the new regions (34, 34'). The microstructure is different from the microstructure of the ceramic layer (10) of the ceramic layer system (1). Preferably, the ceramic layer (10) is a segmented layer, and The new regions (34, 34') have significantly higher porosity and / or are not segmented.

3. The method according to claim 1 or 2, in, For the material of layer (11) used in the region (34), the following material is used: Its material differs from that of the ceramic layer (10) of the ceramic layer system (1). Preferably, the ceramic layer (10) is a segmented layer composed of yttrium oxide-stabilized zirconium oxide. and The ceramic layer portion (34, 34') in the recess (16') has zirconium oxide stabilized by yttrium oxide and ytterbium oxide.

4. A ceramic layer system (11, 111). In particular, ceramic layer systems manufactured according to any one or more of claims 1, 2 or 3, in, The ceramic layer system (11) has three distinct regions (10L, 34, 34', 10R). Among them, compared with the surrounding regions (10L, 10R), the intermediate region (34, 34') between the two regions (10L, 10R) has Significantly higher porosity and / or Significantly different materials.

5. The ceramic layer system according to claim 4, in, The region (34') has a stepped or descending coating thickness.

6. The ceramic layer system according to claim 4 or 5, in, The regions (10L, 10R) surrounding the regions (34, 34') have a segmented microstructure.

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