HEAT SHIELD HAVING AN OUTERMOST YTTRIUM OXIDE COATING, PRODUCTION METHOD AND PRODUCT

Abstract

The corrosion and erosion resistance of ceramic heat shield elements is improved by the use of yttrium oxide on aluminum oxide as a layer or substrate material is provided. A heat is disclosed having aluminum oxide in the substrate or as a layer on a substrate, wherein yttrium oxide, particularly only yttrium oxide, is present as the outermost layer, particularly directly on the aluminum oxide.

Claims

1. A heat shield, comprising aluminum oxide in the substrate or as a layer on a substrate, wherein yttrium oxide, is present as the outermost layer.

2. The solid ceramic heat shield as claimed in claim 1, in which the material of the substrate comprises mullite, with an intermediate aluminum oxide layer and an outermost yttrium oxide layer.

3. The solid ceramic heat shield as claimed in claim 1, in which the material of the substrate comprises mullite and aluminum oxide, particularly consists thereof.

4. The solid ceramic heat shield as claimed in claim 1, in which the material of the substrate consists only of aluminum oxide.

5. The heat shield as claimed in claim 1, which at least comprises a metallic substrate, a metallic adhesion promoter layer, with an aluminum oxide layer formed by oxidation and/or a separately applied aluminum oxide layer, on which an outermost yttrium oxide layer is applied.

6. The heat shield as claimed in claim 5, in which a ceramic thermal barrier coating, is present between a metallic adhesion promoter layer and an aluminum oxide layer.

7. The heat shield as claimed in claim 1, in which the yttrium oxide layer only comprises yttrium oxide, in particular consists thereof, and/or only yttrium oxide is used.

8. A method for producing a heat shield, in which, starting from a heat shield as claimed in claim 1, a heat treatment is carried out at least 1573K, for at least one hour.

9. A heat shield, produced as claimed in claim 8.

Description

BRIEF DESCRIPTION

[0011] Some of the embodiments will be described in detail, with references to the following Figures, wherein like designations denote like members, wherein:

[0012] FIG. 1 shows a solid ceramic heat shield element;

[0013] FIG. 2 shows a metallic heat shield with a metallic substrate;

[0014] FIG. 3 shows a further exemplary embodiment of the invention on the basis of FIG. 2; and

[0015] FIG. 4 shows a layer that has solid ceramic and comprises mullite and/or aluminum oxide.

DETAILED DESCRIPTION

[0016] The figures and the description only represent exemplary embodiments of the invention.

[0017] In FIG. 1, a solid ceramic heat shield 1 is represented.

[0018] The substrate 4 consists of solid ceramic as described above and comprises mullite and/or aluminum oxide or preferably even only aluminum oxide (Al.sub.2O.sub.3) (FIG. 4: 4, 1111). An aluminum oxide layer 7 is applied as described above on the mullite or on the aluminum oxide/mullite of the substrate 4, 4.

[0019] According to embodiments of the invention, an yttrium oxide layer 10 is applied as the outermost layer. With a pure aluminum oxide substrate (4), there is no need for the aluminum oxide layer 7 (FIG. 4).

[0020] FIG. 2 shows a metallic heat shield 11 with a metallic substrate 40, on which a metallic adhesion promoter layer 42 is present, particularly an NiCoCrAlY alloy with an aluminum oxide layer 70, which has formed or is present as a result of deliberate oxidation of a metallic adhesion promoter layer 42 and/or by application of an aluminum oxide layer. An yttrium oxide layer 101 is likewise present as the outermost layer.

[0021] FIG. 3 shows a further exemplary embodiment 111 of the invention on the basis of FIG. 2, in which a ceramic thermal barrier coating (TBC) 80 is also present on the metallic adhesion promoter layer 42 with an aluminum oxide layer 71, as is known from ceramic protection systems of turbine blades. In addition, an outermost yttrium oxide layer 100 is likewise present.

[0022] A ceramically forming aluminum oxide layer (TGO) is also present between the metallic adhesion promoter layer 42 and the TBC 80.

[0023] The yttrium oxide layer 10, 100, 101 or the yttrium oxide preferably only comprises yttrium oxide, particularly consists thereof.

This means that there is no yttrium oxide as a stabilizer of ZrO.sub.2 such as a Y.sub.2O.sub.3ZrO.sub.2.

[0024] The yttrium oxide or the yttrium oxide layer 10, 100, 101 is preferably applied directly on the aluminum oxide or on the aluminum oxide layer 7, 70, 71.

[0025] The aforementioned heat treatment causes an yttrium garnet layer to form (FIG. 1 to FIG. 4).

[0026] Although the invention has been illustrated and described in greater detail with reference to the preferred exemplary embodiment, the invention is not limited to the examples disclosed, and further variations can be inferred by a person skilled in the art, without departing from the scope of protection of the invention.

[0027] For the sake of clarity, it is to be understood that the use of a or an throughout this application does not exclude a plurality, and comprising does not exclude other steps or elements.