Ceramic material, powder and layer system

Abstract

By selecting specific stabilizers and an adjusted proportion, an improved ceramic material for thermal insulation is achieved: Ceramic material based on zirconium oxide (ZrO2) with 5.5 wt.% to 8.5 wt.% base stabilizers: Yttrium oxide (Y2O3) and / or hafnium oxide (HfO2) as well as ytterbium oxide (Yb2O3) as an additional stabilizer: 14.0 wt.% to 16.0 wt.%.

Description

[0001] The invention relates to a ceramic material and a powder, each of which is used for ceramic layer systems.

[0002] Ceramics generally exhibit high temperature stability and are therefore often used as ceramic coatings (TBC) on high-temperature components such as turbines, especially gas turbines.

[0003] US 7,001,859 B2 discloses a zirconium oxide-based TBC with stabilizers of ytterbium oxide, yttrium oxide and gadolinium oxide.

[0004] There is a constant effort to improve the thermal insulation properties of the ceramic material.

[0005] It is therefore an object of the invention to solve the above-mentioned problem.

[0006] The object is achieved by a ceramic according to claim 1, a ceramic powder according to claim 7 and a layer system according to claim 8.

[0007] The subclaims list further advantageous measures which can be combined with each other as desired to achieve further advantages.

[0008] Ceramic materials, powders or ceramic layers based on zirconium oxide with stabilizers are known, although fully stabilized zirconium oxide is often used due to its better thermal stability.

[0009] The aim of the idea is to use fully stabilized zirconium oxide with improved, particularly thermal, stability.

[0010] The zirconium oxide is stabilized with 5.5 wt% to 8.5 wt%, in particular with 6.0 wt.% to 8.0 wt.% Basic stabilizers: yttrium oxide and hafnium oxide as well as with at least one additional stabilizer: 14.0 wt% to 16.0 wt% ytterbium oxide. Preferably, erbium oxide (Er2O3) is not used as a stabilizer.

[0011] A ceramic powder made from the ceramic material can contain additional components. These include, in particular, a binder for binder jet printing (3D printing), additives in the production of slurries, or abrasives such as cubic boron nitride, c-BN, or other refractory metals that differ from the ceramic material and are not based on zirconium oxide. The abrasives can be used for sealing systems in turbine blades, where they can grind into softer materials, such as highly porous ceramics (abradables) or highly porous ceramic coatings.

[0012] In a shift system 1 ( Fig. 1) a ceramic layer 10 is applied to metal, wherein in the case of preferably used nickel or cobalt-based superalloys a metallic adhesion layer 7 is present, which forms a layer of aluminium oxide (TGO) during use or in advance, wherein the metallic adhesion promoter layer preferably has an aluminide, platinum aluminide or as a base a NiCoCrAlY alloy (NiCoCrAlYRe, NiCoCrAlYSi, NiCoCrAlYTa, NiCoCrAlYFe, NiCoCrAlYFeSi, NiCoCrAlYTaSi,..).

[0013] The ceramic powder for the ceramic layer 10 can be optimized with regard to its grain size or sieved accordingly, or bimodal distributions can be selected.

[0014] The ceramic layer 10 made of the ceramic material or ceramic powder can be produced by means of EB-PVD, plasma spraying (APS, ...), HVOF, by means of suspensions, etc. Preferably, the ceramic layer 10 has a columnar structure or a segmented or DVC (Dense Vertical Cracked) structure.

[0015] The ceramic layer 10 preferably has a layer thickness of 100µm to 1000µm.

[0016] The porosity is preferably below 10vol%, especially below 8vol%.

[0017] As in the Fig. 2, this ceramic layer 10 can also have a ceramic sublayer 13 in a ceramic layer system (1'), the layer thickness of which, however, is at least 10%, in particular at least 20% thinner than that of the ceramic material of the ceramic layer 10 according to the invention.

[0018] The ceramic underlayer 13 preferably comprises partially stabilized, tetragonal zirconium oxide, in particular 8YSZ, i.e. partially stabilized yttrium-stabilized zirconium oxide.

[0019] The ceramic material according to the invention preferably comprises 4.5 wt.% to 5.5 wt.% yttrium oxide (Y2O3), in particular 5.0 wt.% yttrium oxide (Y2O3).

[0020] The ceramic material preferably also comprises: hafnium oxide (HfO2) with 1.0 wt.% to 3.0 wt.%, in particular 2.5 wt.% hafnium oxide (HfO2).

[0021] The ceramic material preferably comprises 14.5 wt.% to 15.5 wt.% ytterbium oxide (Yb2O3), in particular 15.0 wt.% Yb2O3.

[0022] Impurities of, in particular, aluminum (Al), calcium (Ca), iron (Fe), magnesium (Mg), silicon (Si) and / or titanium (Ti) in the form of oxides are tolerated, in particular up to a maximum of 0.4 wt.% in each case.

[0023] Advantageous compositions are: 5.2% Y2O3 / 15.2% Yb2O3 / ZrO2 or 4.8% Y2O3 / 2.1% HfO2 / 15.1% Yb2O3 / ZrO2 and as layer 10 with 8YSZ as ceramic underlayer 13, it exhibits significantly better temperature change behavior than 8YSZ / 20YSZ. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] US 7,001,859 B2

[0003]

Claims

[1] Ceramic material based on zirconium oxide (ZrO2) with 4.5 wt% to 8.5 wt% basic stabilizers: in particular with 6.0 wt.% to 8.0 wt.% basic stabilizers: Yttrium oxide (Y2O3) and / or hafnium oxide (HfO2) and 14.0 wt% to 16.0 wt% additional stabilizer: ytterbium oxide (Yb2O3). [2] Ceramic material according to claim 1, having at least 4.5 wt% and maximum 5.5 wt% yttrium oxide (Y2O3), in particular 5.0 wt% yttrium oxide (Y2O3) [3] Ceramic material according to one or both of claims 1 or 2, in which the content of hafnium oxide (HfO2) is 2.0 wt.% to 3.0 wt.%, in particular 2.5 wt.% hafnium oxide (HfO2). [4] Ceramic material according to one or more of claims 1, 2 or 3, having, at least comprising ZrO2-HfO2-Y2O3-Yb2O3 and in each case a maximum of 0.4 wt.% of other oxides, in particular of aluminum (Al), calcium (Ca), iron (Fe), magnesium (Mg), silicon (Si) and / or titanium (Ti). [5] Ceramic material according to one or more of claims 1, 2 or 3, having, at least comprising ZrO2-Y2O3-2O3 and maximum 0.4 wt.% of other oxides, in particular hafnium (Hf), aluminum (Al), calcium (Ca), iron (Fe), magnesium (Mg), silicon (Si) and / or titanium (Ti). [6] Ceramic material according to one or more of claims 1, 2, 3, 4 or 5, comprising 14.5 wt% to 15.5 wt% ytterbium oxide (Yb2O3), in particular 15.0 wt% ytterbium oxide (Yb2O3). [7] Ceramic powder having, in particular consisting of, a composition of a material according to one or more of claims 1 to 6, optionally featuring: Binder and / or Abrasives. [8] Layer system (1, 1') at least having a metallic substrate (4), optionally a metallic adhesion promoter layer (7) and at least one ceramic layer (10) based on the material according to the invention according to claims 1 to 6 or a powder according to claim 7. [9] Layer system according to claim 8, having a metallic adhesion promoter layer (7) between the ceramic layer (13, 10) and the metallic substrate (4), especially based on NiCoCrAlY. [10] Layer system according to one or both of claims 8 or 9, in which a ceramic underlayer (13) is present under the ceramic layer (10) made of a material according to one or more of claims 1, 2, 3, 4, 5 or 6, wherein the ceramic underlayer (13) is at least 10%, in particular at least 20% thinner than the ceramic layer (10) and wherein the ceramic underlayer (13) comprises tetragonal zirconium oxide, in particular partially stabilized zirconium oxide, especially 8YSZ. [11] Layer system according to one or more of claims 8, 9 or 10, wherein the ceramic layer (10) preferably has a layer thickness of 100µm to 1000µm.

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