Two-layer coating system, ceramic powder and layer

Abstract

The invention relates to a coating system (1) comprising at least one metallic substrate (4), optionally a metallic bond coat (7) on the substrate (4), and a ceramic base layer (10) consisting of tetragonal zirconium oxide, containing 3.5 to 8.0 wt.% yttrium oxide and 6.0 to 8.0 wt.% ytterbium oxide, and a ceramic top layer (13) consisting of cubic zirconium oxide on the ceramic base layer (10).

Description

Technical Field

[0001] This invention relates to a double-coating system, ceramic powder, and layers. Background Technology

[0002] Ceramics typically exhibit excellent stability at high temperatures, making them a popular choice for coatings on high-temperature components such as turbines, particularly gas turbines. An important aspect of these applications is the bonding between the ceramic coating and the substrate (usually a metal substrate).

[0003] Metallic adhesive coatings, such as NiCoCrAlY-based adhesive coatings, and ceramic adhesive layers are known to form a two-layer ceramic coating system.

[0004] Therefore, the aim is to improve the thermal insulation performance of ceramic coating systems. Summary of the Invention

[0005] The purpose of this invention is to solve the above-mentioned problems.

[0006] The above objective is achieved by the coating system according to claim 1, the powder according to claim 6, and the layer according to claim 7.

[0007] Other advantageous measures are described in the dependent claims, and these measures can be combined with each other in any way to achieve additional advantages.

[0008] Ceramic coatings based on stabilized zirconia are known, among which fully stabilized zirconia (FSZ) is frequently used due to its better thermal stability.

[0009] However, the present invention aims to use partially stabilized zirconium oxide and fully stabilized zirconium oxide with improved thermal stability. Attached Figure Description

[0010] The accompanying drawings schematically illustrate an exemplary embodiment of the present invention.

[0011] The accompanying drawings and description only illustrate exemplary embodiments of the present invention. Detailed Implementation

[0012] In coating system 1, a ceramic substrate 10 is applied to a metal, wherein when a nickel-based or cobalt-based superalloy is used as the substrate 4, a metal bonding coating 7 is preferably present.

[0013] The metal bonding coating 7 preferably comprises aluminum compounds, platinum aluminum compounds, or is based on a NiCoCrAlY-X alloy (optionally X = Ta, Re, Fe and / or Si) to form aluminum oxide (TGO, not shown).

[0014] The ceramic surface layer 13 located on the ceramic material according to the present invention can be prepared by plasma spraying (APS, etc.), HVOF, EB-PVD, SPPS, and preferably has a columnar or segmented structure.

[0015] The thickness of the ceramic surface layer 13 is preferably from 100 μm to 1000 μm.

[0016] Similarly, a ceramic base layer 10 is also present, but its thickness is at least 20% thinner than that of the ceramic surface layer 13.

[0017] All the following values ​​are expressed as a weight percentage (wt%).

[0018] The ceramic substrate 10 contains partially stabilized zirconium oxide.

[0019] The partially stabilized zirconia in the ceramic substrate 10 is stabilized with 3.5% to 8.0%, particularly 4.0% to 6.5% of the base stabilizer yttrium oxide (Y2O3) and 6.0% to 8.0% of ytterbium oxide (Yb2O3) and optional hafnium oxide / alumina.

[0020] The ceramic material preferably contains 3.0% to 4.0% yttrium oxide (Y2O3), more preferably 6.5% to 7.5% ytterbium oxide (Yb2O3), and also preferably optionally contains 0.2% to 4.0%, particularly 0.5% to 2.5% hafnium oxide (HfO2).

[0021] A ceramic surface layer 13 with cubic zirconia structure is applied on the ceramic base layer 10.

[0022] The cubic zirconia used for the ceramic surface layer 13 preferably contains yttrium oxide-stabilized zirconia, wherein the proportion of yttrium oxide is from 18.0% to 22.0%, particularly 20.0%.

[0023] Cubic zirconia with yttrium oxide, ytterbium oxide and gadolinium oxide stabilizers can also be used as the ceramic surface layer 13.

[0024] Preferably, the following proportions are subsequently used: 8.5% - 11.5% yttrium oxide, 4.0% - 7.0% ytterbium oxide, and 3.5% - 6.5% gadolinium oxide; most preferably: 9.0% - 11.0% yttrium oxide, 4.5% - 6.5% ytterbium oxide, and 4.0% - 6.0% gadolinium oxide.

[0025] Optimal results are achieved with 9.5% - 10.0% yttrium oxide, 5.2% - 6.0% ytterbium oxide, and 4.8% - 5.6% gadolinium oxide.

[0026] Accordingly, the powder used for the cubic zirconia contains at least: 8.5% - 11.5% yttrium oxide, 4.0% - 7.0% ytterbium oxide and 3.5% - 6.5% gadolinium oxide, preferably 9.0% - 11.0% yttrium oxide, 4.5% - 6.5% ytterbium oxide and 4.0% - 6.0% gadolinium oxide.

[0027] The powder may contain polymers for forming pores during the coating process, binders for slip-casting or adhesive jet printing, or abrasive particles (non-zirconia, especially BN, ZrC, etc.).

[0028] Example of ceramic base layer 10:

[0029] • 3.6% Y2O3 / 6.5% Yb2O3 – ZrO2

[0030] • 3.4% Y2O3 / 6.7% Yb2O3 / 0.5% Al2O3 – ZrO2

[0031] • 3.6% Y2O3 / 6.5% Yb2O3 / 1.2% HfO2 – ZrO2

[0032] • 3.5% Y2O3 / 6.4% Yb2O3 / 1.1% HfO2 / 0.3% Al2O3 - ZrO2;

[0033] Examples of ceramic surface layer 13 that can be used in combination with ceramic base layer 10:

[0034] • 20% Y2O3 - ZrO2

[0035] • 10.0% Y2O3 / 5.5% Yb2O3 / 5.3% Gd2O3 - ZrO2.

Claims

1. Coating system (1), Includes at least one metal substrate (4). Optionally, a metal bonding coating (7) is applied to the metal substrate (4), and A ceramic substrate (10) composed of tetragonal zirconia comprises 3.5 wt% to 8.0 wt% yttrium oxide, particularly 4.0 wt% to 6.5 wt% yttrium oxide, and 6.0 wt% to 8.0 wt% ytterbium oxide, and optionally hafnium oxide and / or aluminum oxide, and A ceramic surface layer (13) composed of cubic zirconia on a ceramic base layer (10).

2. The coating system according to claim 1, The ceramic surface layer (13) contains yttrium oxide-stabilized zirconium oxide. The proportion of yttrium oxide is from 18.0% to 22.0% by weight, particularly 20.0% by weight, and particularly contains only yttrium oxide.

3. The coating system according to claim 1, The ceramic surface layer (13) comprises zirconium oxide and has yttrium oxide, ytterbium oxide and gadolinium oxide as stabilizers. The preferred composition includes: 8.5% - 11.5% yttrium oxide, 4.0% - 7.0% ytterbium oxide, and 3.5% - 6.5% gadolinium oxide. Preferably, it contains 9.0% - 11.0% yttrium oxide, 4.5% - 6.5% ytterbium oxide, and 4.0% - 6.0% gadolinium oxide. Particularly preferred are: 9.5% - 10.0% yttrium oxide, 5.2% to 6.0% ytterbium oxide, and 4.8% - 5.6% gadolinium oxide.

4. The coating system according to one or more of claims 1, 2, or 3, Includes a metal bonding coating (7) between the ceramic layer (13, 10) and the metal substrate (4). Especially on the metal substrate (4), The adhesive layer (7) comprises a NiCoCrAlY-X type alloy, wherein X is optionally Ta, Re and / or Si, particularly NiCoCrAlY or NiCoCrAlY-Ta.

5. The coating system according to one or more of claims 1, 2, 3 or 4, The ceramic substrate (10) is at least 20% thinner than the ceramic surface layer (13).

6. Powder used for ceramic layers, It must contain at least: 8.5% - 11.5% yttrium oxide, 4.0% - 7.0% ytterbium oxide, and 3.5% - 6.5% gadolinium oxide. Preferably, the composition includes 9.0% - 11.0% yttrium oxide, 4.5% to 6.5% ytterbium oxide, and 4.0% - 6.0% gadolinium oxide. More preferably, 9.5% to 10.0% yttrium oxide, 5.2% to 6.0% ytterbium oxide and 4.8% to 5.6% gadolinium oxide.

7. A layer comprising the composition of claim 6, or made of the powder of claim 6.

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