Low thermal conductivity high toughness tbc compositions

Abstract

A low thermal conductivity, high toughness TBC composition is provided comprising a yttria-rare earth doped zirconium oxide having a tetragonal structure and having the formula: Y a Ln b Ce x Zr 1‑a‑b‑x O 2‑δ , wherein Ln is a mixture of rare earth elements; 0.01 < a < 0.051; 0.01 < b < 0.051, such that Y and each rare earth element are contained in the composition in substantially equal molar amounts; 0.05 < (a+b) < 0.07; 0 < x < 0.051; and 0 < δ < 0.05. Also provided are methods of forming a coating comprising the composition and the resulting coated components.

Description

TECHNICAL FIELD

[0001] The present invention relates generally to compositions suitable for use in coating systems on components exposed to high temperature environments, such as through hot gas flow paths of gas turbine engines. More particularly, the present invention relates to compositions suitable for use in thermal barrier coating (TBC) systems. BACKGROUND

[0002] The use of thermal barrier coatings on components of gas turbine engines, such as combustors, high pressure turbine (HPT) blades and vanes, has increased. Generally, the thermal insulation of TBCs enables such components to withstand higher operating temperatures, increasing component durability and improving engine reliability. To maintain the effectiveness of the TBC throughout the planned life cycle of the component it protects, it is desirable for the TBC to have a low thermal conductivity throughout the life cycle of the component, including high temperature excursions. Additionally, it is desirable for the TBC to have high toughness, reducing damage caused by erosion and impact to rotating components of the HPT, combustor components, and static turbine components, such as turbine nozzles. A low thermal conductivity TBC can improve engine efficiency by reducing heat loss and potentially allowing higher temperature operation.

[0003] Current TBC materials, 8YSZ, are known for their high toughness as well as high thermal conductivity. Low thermal conductivity compositions, such as 55YSZ, lack high toughness. Therefore, it is desirable to further improve TBC technology, particularly when the TBC is used to thermally insulate components for which more demanding engine designs are required. SUMMARY

[0004] In one aspect, the present invention provides a composition comprising: a yttria-rare earth doped zirconium oxide having a tetragonal structure and having the formula: Y a Ln b Ce x Zr 1-a-b-x O 2-δ wherein Ln is a mixture of rare earth elements; 0.01 < a < 0.051; 0.01 < b < 0.051, such that Y and each rare earth element are contained in the composition in substantially equal molar amounts; 0.05 < (a+b) < 0.07; 0 < x < 0.051; and 0 < δ < 0.05.

[0005] In another aspect, the present invention provides a method of forming a coated component, the method comprising: applying a layer to a surface of a substrate, wherein the layer comprises the above-described composition.

[0006] In yet another aspect, the present application provides a coated component comprising: a substrate having a surface; and a thermal barrier coating on the surface; wherein the thermal barrier coating comprises a layer comprising the composition described above.

[0007] In yet another aspect, the present application provides a coated component comprising: a substrate having a surface; and a thermal barrier coating on the surface; wherein the thermal barrier coating comprises a layer comprising yttria-rare earth doped zirconium oxide having a tetragonal structure, the layer having a thermal conductivity of 1.6 W / m-k to 2 W / m-k at 1000°C measured by laser flash method according to ASTM E1461-13. BRIEF DESCRIPTION OF DRAWINGS

[0008] A complete and enabling disclosure of the present application, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification, which makes reference to the appended drawings, in which:

[0009] Figure 1 is a cross-sectional schematic view of an exemplary coated component; and

[0010] Figure 2 is a schematic cross-sectional view of an exemplary gas turbine engine according to various embodiments of the inventive subject matter.

[0011] Repetition of the reference numerals in the specification and drawings is intended to represent the same or similar features or elements throughout the specification and drawings. DETAILED DESCRIPTION

[0012] Definitions

[0013] As used herein, the term "exemplary" means "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, unless otherwise noted, all implementations described herein are to be considered exemplary in nature.

[0014] The term "gas turbine engine" refers to an engine having a turbine machine as all or a portion of its power source. Exemplary gas turbine engines include turbofan engines, turboprop engines, turbojet engines, turboshaft engines, and the like, as well as hybrid versions of one or more of these engines. The term "turbine machine" or "turbomachine" refers to a machine that includes one or more compressors, a heat generating section (e.g., a combustion section), and one or more turbines that together produce a torque output.

[0015] In the present invention, when a layer is described as being "on" or "over" another layer or substrate, it is to be understood that unless explicitly stated otherwise, the layers can be in direct contact with one another or have another layer or feature between them. Thus, these terms describe the relative position of the layers with respect to one another and do not necessarily imply "on top of" as the relative position above or below is dependent on the orientation of the device with respect to the viewer.

[0016] In the present invention, chemical elements are discussed using their common chemical abbreviations, such as are common on the Periodic Table of Elements. For example, hydrogen is represented by its common chemical abbreviation, H; helium is represented by its common chemical abbreviation, He; and so on.

[0017] As used herein, "Ln" means a rare earth element or a mixture of rare earth elements. More specifically, "Ln" means the rare earth elements scandium (Sc), yttrium (Y), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), or mixtures thereof.

[0018] As used herein, the term "substantially (essentially) free of" shall be understood to mean either completely free of the recited ingredient or containing trace amounts of the recited ingredient. "Trace amounts" are quantitative levels of chemical ingredients that are nearly undetectable and do not provide a benefit to the functional or aesthetic properties of the subject composition. The term "substantially (essentially) free of" also includes completely free of.

[0019] As used herein, the term "substantially (essentially) equal" shall be understood to include minor trace variations in quantitative levels that are nearly undetectable and do not provide a benefit to the functional or aesthetic properties of the subject composition. The term "substantially (essentially) equal" also includes completely equal.

[0020] Reference will now be made in detail to implementations of the present invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the present invention and is not meant as a limitation of the present invention. In fact, many modifications and variations to the present invention can be apparent to those skilled in the art upon reading this description, which is provided by way of example of the application. For instance, features illustrated or described as part of one implementation can be used with another implementation to yield still a further implementation. Thus, it is intended that the present invention covers all such modifications and variations of this invention which come within the scope of the following claims and their equivalents.

[0021] Compositions based on rare earth doped zirconium oxides having a tetragonal structure and coatings formed from such compositions are generally disclosed. These compositions and coatings can have relatively low thermal conductivities (e.g., 1.6 W / m-K to 2 W / m-K at 1000°C as measured by laser flash method according to ASTM E1461-13) and indentation fracture toughnesses of 4 MPa-m 1 / 2 to 8 MPa-m 1 / 2 in 95-100% dense pucks. Generally, these compositions can be used to form TBC layers having lower thermal conductivities as well as enhanced toughness and / or CMAS protection. As a result, the resulting TBCs will allow for higher component surface temperatures and / or reduced coating thicknesses for the same surface temperatures. Reduced TBC thicknesses, especially in applications requiring relatively thick TBCs (e.g., combustors), will result in significant cost reductions as well as weight benefits. Additionally, the resulting TBCs can provide improved protection to the substrate placed thereunder to reduce erosion that can occur over the life of the component in the absence of the compositions present in the TBC layer.

[0022] The compositions generally comprise a rare earth doped zirconium oxide having a tetragonal structure. In one embodiment, the composition has a formula as shown in Formula 1 :

[0023] Formula 1 : Y a Ln b Ce x Zr 1-a-b-x O 2-δ ,

[0024] wherein,

[0025] Ln is a mixture of rare earth elements;

[0026] 0.01 < a < 0.05 1;

[0027] 0.01 < b < 0.05, such that Y and each Ln are contained in the composition in substantially equal molar amounts;

[0028] 0.05 < (a + b) < 0.07;

[0029] 0 < x < 0.05; and

[0030] 0 < δ < 0.05.

[0031] Without wishing to be bound by any particular theory, it is believed that the presence of too much Y in the rare earth doped zirconium oxide can lead to the formation of a cubic phase that is less ductile. Further, it is believed that mixtures of rare earth elements (Ln) are often substituted for Y in the composition to maintain the tetragonal structure while adding a rare earth dopant to the composition.

[0032] In particular embodiments, Ln can include at least 2 of La, Sm, Gd, Yb, Nd, Eu, Dy, Ho, Er, and Lu, for example at least 3 of La, Sm, Gd, Yb, Nd, Eu, Dy, Ho, Er, and Lu. In a particular embodiment, Ln can include at least 4 of La, Sm, Gd, Yb, Nd, Eu, Dy, Ho, Er, and Lu. In a particular embodiment, Ln is substantially free of Tb and Pr.

[0033] Generally, δ refers to oxygen vacancies formed within the rare earth doped zirconium oxide to balance the valence state of the composition based on the particular Y / Ln / Ce / Zr composition present in the compound. In particular embodiments, 0 < δ < 0.03.

[0034] In a particular embodiment, a is 0.01 to 0.017, such that the yttrium-rare earth doped zirconium oxide has a formula according to Formula 2:

[0035] Formula 2: Y a Ln 1 b1 Ln 2 b2 Ln 3 b3 Ln 4 b4 Ce x Zr 1-a-b1-b2-b3-b4-x O 2-δ ,

[0036] wherein,

[0037] Ln 1 , Ln 2 , Ln 3 , and Ln 4 each represent a different rare earth element or mixture of rare earth elements from one another;

[0038] 0.01 < a < 0.017;

[0039] 0.01 < b1 < 0.017;

[0040] 0.01 < b2 < 0.017;

[0041] 0.01 < b3 < 0.017;

[0042] 0 < b4 < 0.014;

[0043] a = b1 = b2 = b3;

[0044] 0.05 < (a + b1 + b2 + b3 + b4) < 0.07;

[0045] 0 < x < 0.051; and

[0046] 0.01 < δ < 0.05.

[0047] In the composition of Formula 2, a, b1, b2, and b3 can all be substantially equal to one another (e.g., a = b1 = b2 = b3), while b4 is 0 or also substantially equal to a, b1, b2, and b3. For example, a, b1, b2, b3, and b4 can all be substantially equal to 0.01 (e.g., a = b1 = b2 = b3 = b4 = 0.01), substantially equal to 0.012 (e.g., a = b1 = b2 = b3 = b4 = 0.012), or substantially equal to 0.014 (e.g., a = b1 = b2 = b3 = b4 = 0.014). Alternatively, when b4 is 0, then a, b1, b2, and b3 can all be substantially equal to 0.012 (e.g., a = b1 = b2 = b3 = 0.012, and b4 is 0), 0.014 (e.g., a = b1 = b2 = b3 = 0.014, and b4 is 0), or 0.017 (e.g., a = b1 = b2 = b3 = 0.017, and b4 is 0).

[0048] In one particular embodiment, the composition can be substantially free of Ce; for example, x can be 0, such that the composition is free of Ce. In another embodiment, x is greater than 0, such that Ce is present in the composition, for example, where 0.01 < x < 0.05.

[0049] Particularly suitable compositions of rare earth doped zirconium oxides having a tetragonal structure can include, but are not limited to:

[0050] Y 0.01 La 0.01 Gd 0.01 Yb 0.01 Sm 0.01 Zr 0.95 O2;

[0051] Y 0.01 Sm 0.01 Yb 0.01 Gd 0.01 Nd 0.01 Zr 0.95 O 2-δ ;

[0052] Y 0.012 Sm 0.012 Yb 0.012 Gd 0.012 Zr 0.93 Ce 0.02 O 2-δ ;

[0053] Y 0.01 Sm 0.01 Ho 0.01 Gd 0.01 Eu 0.01 Zr 0.95 O 2-δ ;

[0054] Y 0.01 Sm 0.01 Dy 0.01 Gd 0.01 Er 0.01 Zr 0.95 O 2-δ ;

[0055] or mixtures thereof.

[0056] As noted above, compositions of rare earth doped zirconium oxides having a tetragonal structure are particularly suitable for use in the layer of a thermal barrier coating on a component.

[0057] For example, with reference to Figure 1 , an exemplary coated component 100 is shown, formed of a substrate 102 having a surface 103 and a coating system 106 thereon. Typically, the coating system 106 includes a bond coat 104 on the surface 103 of the substrate 102 and a TBC 108 on the bond coat 104. In the illustrated embodiment, the bond coat 104 is directly on the surface 103 without any layers therebetween. Bond coat materials that are widely used in TBC systems can include, but are not limited to, oxidation resistant overlay coatings, such as MCrAlX (where M is iron, cobalt and / or nickel and X is yttrium or other rare earth element), and oxidation resistant diffusion coatings, such as diffusion aluminides containing aluminum intermetallics.

[0058] The substrate 102 can be any suitable material, for example, a metal such as steel or a superalloy (e.g., a nickel-based superalloy, a cobalt-based superalloy, or an iron-based superalloy, such as Rene N5, N500, N4, N2, IN718, Hastelloy X, or Haynes 188) or other suitable material for withstanding high temperatures. The coating system 106 can be disposed along one or more portions of the substrate 102, or substantially over the entire exterior of the substrate 102. In particular embodiments, the coating system 106 can have a total thickness of 50 pm (i.e., micrometers or pm) to 2500 pm (e.g., 100 pm to 700 pm).

[0059] The TBC 108 can be formed from a plurality of individual layers 114. In one embodiment, at least one of the layers 114 of the TBC 108 includes a layer comprising a composition of a rare earth-doped zirconium oxide having a tetragonal structure (e.g., having a formula of Formula 1). For example, at least one of the layers 114 of the TBC 108 can include at least 80 wt% of a composition of a rare earth-doped zirconium oxide having a tetragonal structure (e.g., having a formula of Formula 1). In one embodiment, at least one of the layers 114 of the TBC 108 can include 90 wt% to 100 wt% of a composition of a rare earth-doped zirconium oxide having a tetragonal structure (e.g., having a formula of Formula 1). In one particular embodiment, at least one of the layers 114 of the TBC 108 (which includes a composition of a rare earth-doped zirconium oxide having a tetragonal structure (e.g., having a formula of Formula 1)) is substantially free of yttria-rare earth-doped zirconium oxide having a cubic structure.

[0060] In particular embodiments, each of the layers 114 of the TBC 108 can have a layer thickness of 25 pm to 100 pm (e.g., 25 pm to 50 pm).

[0061] One or more of the individual layers 114 can be formed from a stable ceramic capable of withstanding a fairly high temperature gradient, such that the coated metal component can be operated at a gas temperature above the metal melting point. For example, the stable ceramic material can be one or more of: yttria-stabilized zirconia (YSZ) and other rare earth stabilized zirconia compositions, mullite (3AI2O3-2SiO2), alumina, ceria (CeO2), lanthanum zirconate, rare earth oxides (e.g., La2O3, Nb2O5, Pr2O3, CeO2), and metal-glass composites, and combinations thereof (e.g., alumina and YSZ, or ceria and YSZ). In addition to having high temperature stability, YSZ also has a good combination of high toughness and chemical inertness, with a coefficient of thermal expansion that is relatively well matched to that of the coated metal component.

[0062] The individual layers 114 can be formed by any suitable process. For example, one or more of the individual layers 114 can be formed by air- plasma spray (APS), suspension plasma spray (SPS), solution precursor plasma spray (SPPS), electron beam physical vapor deposition (EBPVD), high velocity oxy-fuel spray (HVOF), electrostatic spray assisted vapor deposition (ESAVD), and direct vapor deposition.

[0063] In one embodiment, the TBC 108 can include a layer of YSZ (e.g., 8YSZ) closest to the substrate 102 (e.g., directly on the bond coat 104). Thus, yttria-stabilized zirconia can form a barrier coating between the substrate and the layer comprising a composition having a tetragonal structure of a rare earth doped zirconium oxide (e.g., having a formula of Formula 1).

[0064] The coated component 100 is particularly suitable for use as a component present in a high temperature environment, such as those components present in a gas turbine engine, such as combustor components, turbine blades, shrouds, nozzles, heat shields, and vanes. In particular, the coated component 100 can be a component located within a hot gas flow path of a gas turbine, such that the coating system 106 forms a thermal barrier for the substrate 102 positioned thereunder to protect the component 100 within the gas turbine when exposed to the hot gas flow path.

[0065] Figure 2 is a schematic cross-sectional view of a gas turbine engine in accordance with an example embodiment of the present application. More particularly, for Figure 2 embodiments of the present application, the gas turbine engine is a high-bypass turbofan engine 10, referred to herein as "turbofan engine 10." As shown in Figure 2 the turbofan engine 10 defines an axial direction A (extending parallel to a longitudinal axis 12 for reference) and a radial direction R. Generally, the turbofan engine 10 includes a fan section 14 and a core turbine engine 16 disposed downstream from the fan section 14. Although described below with reference to a turbofan engine 10, the present application is generally applicable to turbine engines, including turbojet engines, turboprop engines, and turboshaft gas turbine engines, including industrial and marine gas turbine engines and auxiliary power units. It is also applicable to other high temperature applications involving water vapor in the gas phase, such as those resulting from the combustion of hydrocarbon fuels.

[0066] The exemplary core turbine engine 16 shown generally includes a substantially tubular outer casing 18 defining an annular inlet 20. The outer casing 18 encloses, in serial flow relationship: a compressor section including a booster or low pressure (LP) compressor 22 and a high pressure (HP) compressor 24; a combustion section 26; a turbine section including a high pressure (HP) turbine 28 and a low pressure (LP) turbine 30; and an ejection exhaust nozzle section 32. A high pressure (HP) shaft or spool 34 drivingly connects the HP turbine 28 with the HP compressor 24. A low pressure (LP) shaft or spool 36 drivingly connects the LP turbine 30 with the LP compressor 22.

[0067] For the embodiment shown, the fan section 14 includes a variable pitch fan 38 having a plurality of fan blades 40 connected in spaced relation to a disk 42. As shown, the fan blades 40 extend generally outwardly from the disk 42 along a radial direction R. Since the fan blades 40 are operatively connected to a suitable actuating member 44 configured to collectively and uniformly vary the pitch of the fan blades 40, each fan blade 40 is rotatable about a pitch axis P relative to the disk 42. The fan blades 40, disk 42, and actuating member 44 are rotated together about the longitudinal axis 12 by the LP spool 36 (through an optional power gear box 46). The power gear box 46 includes a plurality of gears for progressively reducing the rotational speed of the LP spool 36 to a more efficient fan rotational speed.

[0068] Still referring to the exemplary embodiment of Figure 2 The disk 42 is covered by a rotatable front nacelle 48 having an aerodynamic profile to facilitate airflow through the plurality of fan blades 40. Additionally, the exemplary fan section 14 includes an annular fan casing or outer nacelle 50 circumferentially surrounding the fan 38 and / or at least a portion of the core turbine engine 16. It should be appreciated that the nacelle 50 can be configured to be supported relative to the core turbine engine 16 by a plurality of circumferentially spaced outlet guide vanes 52. Moreover, a downstream section 54 of the nacelle 50 can extend over an outer portion of the core turbine engine 16 so as to define a bypass airflow passage 56 therebetween.

[0069] During operation of the turbofan engine 10, a volume of air 58 enters the turbofan engine 10 through an associated inlet 60 of the nacelle 50 and / or the fan section 14. As the volume of air 58 passes the fan blades 40, a first portion 62 of the air 58 is directed or channeled into the bypass airflow passage 56 as indicated by the arrows, and a second portion 64 of the air 58 is directed or channeled into the LP compressor 22 as indicated by the arrows. The ratio between the first portion 62 of air and the second portion 64 of air is commonly referred to as the bypass ratio. The second portion 64 of air then increases in pressure as it is channeled through the high pressure (HP) compressor 24 and into the combustion section 26 where it is mixed with fuel and combusted to provide combustion gases 66.

[0070] The combustion gases 66 are channeled through the HP turbine 28 where a portion of the thermal and / or kinetic energy from the combustion gases 66 is extracted via sequential stages of HP turbine stator vanes 68 (coupled to the outer casing 18) and HP turbine rotor blades 70 (coupled to the HP shaft or spool 34), causing the HP shaft or spool 34 to rotate, thereby supporting operation of the HP compressor 24. The combustion gases 66 are then channeled through the LP turbine 30 where a second portion of thermal and kinetic energy is extracted from the combustion gases 66 via sequential stages of LP turbine stator vanes 72 (coupled to the outer casing 18) and LP turbine rotor blades 74 (coupled to the LP shaft or spool 36), causing the LP shaft or spool 36 to rotate, thereby supporting operation of the LP compressor 22 and / or rotation of the fan 38.

[0071] Subsequently, the combustion gases 66 are channeled through the jet exhaust nozzle section 32 of the core turbine engine 16 to provide propulsive thrust. At the same time, the pressure of the first portion 62 of air is significantly increased as it is channeled through the bypass airflow passage 56, also providing propulsive thrust, before the first portion 62 of air is exhausted from a fan nozzle exhaust section 76 of the turbofan engine 10. The HP turbine 28, the LP turbine 30, and the jet exhaust nozzle section 32 at least partially define a hot gas path 78 for channeling the combustion gases 66 through the core turbine engine 16.

[0072] Other aspects of the application are provided by the subject matter of the following clauses:

[0073] 1. A composition comprising a yttria-rare earth doped zirconium oxide having a tetragonal structure and having the formula: Y a Ln b Ce x Zr 1-a-b-x O 2-δwherein Ln is a mixture of rare earth elements; 0.01 < a < 0.051 ; 0.01 < b < 0.051, such that Y and each rare earth element are included in the composition in substantially equal molar amounts; 0.05 < (a + b) < 0.07; 0 < x < 0.051 ; and 0 < δ < 0.05.

[0074] 2. The composition of any one of the preceding clauses, wherein x is 0.

[0075] 3. The composition of any one of the preceding clauses, wherein x is 0.01 to 0.05.

[0076] 4. The composition of any one of the preceding clauses, wherein a is 0.01 to 0.017, such that the yttrium-rare earth doped zirconium oxide has the following formula: Y a Ln 1 b1 Ln 2 b2 Ln 3 b3 Ln 4 b4 Ce x Zr 1-a-b1-b2-b3-b4-x O 2-δ , wherein Ln 1 , Ln 2 , Ln 3 , and Ln 4 each represent a different rare earth element or mixture of rare earth elements from one another; 0.01 < a < 0.017; 0.01 < b1 < 0.017; 0.01 < b2 < 0.017; 0.01 < b3 < 0.017; 0 < b4 < 0.017; a = b1 = b2 = b3; 0.05 < (a + b1 + b2 + b3 + b4) < 0.07; 0 < x < 0.051 ; and 0.01 < δ < 0.05.

[0077] 5. The composition of any one of the preceding clauses, wherein a = b1 = b2 = b3 = b4 = 0.01.

[0078] 6. The composition of any one of the preceding clauses, wherein a = b1 = b2 = b3 = 0.012; and b4 is 0.

[0079] 7. The composition of any one of the preceding clauses, wherein a = b1 = b2 = b3 = b4 = 0.012.

[0080] 8. The composition of any one of the preceding clauses, wherein a = b1 = b2 = b3 = 0.014; and b4 is 0.

[0081] 9. The composition of any of the preceding clauses, wherein a = b1 = b2 = b3 = b4 = 0.014.

[0082] 10. The composition of any of the preceding clauses, wherein a = b1 = b2 = b3 = 0.017; and b4 is 0.

[0083] 11. The composition of any of the preceding clauses, wherein Ln comprises at least 2 of La, Sm, Gd, Yb, Nd, Eu, Dy, Ho, Er, and Lu.

[0084] 12. The composition of any of the preceding clauses, wherein Ln is substantially free of Tb and Pr.

[0085] 13. The composition of any of the preceding clauses, wherein the composition has a thermal conductivity at 1000°C of 1.6 W / m-K to 2 W / m-K as measured by laser flash method according to ASTM E1461-13.

[0086] 14. The composition of any of the preceding clauses, wherein the composition is selected from the following: Y 0.01 La 0.01 Gd 0.01 Yb 0.01 Sm 0.01 Zr 0.95 O2; Y 0.01 Sm 0.01 Yb 0.01 Gd 0.01 Nd 0.01 Zr 0.95 O 2-δ ; Y 0.012 Sm 0.012 Yb 0.012 Gd 0.012 Zr 0.9 3Ce 0.02 O 2-δ ; Y 0.01 Sm 0.01 Ho 0.01 Gd 0.01 Eu 0.01 Zr 0.95 O 2-δ ; Y 0.01 Sm 0.01 Dy 0.01 Gd 0.01 Er 0.01 Zr 0.95 O 2-δ ; and mixtures thereof.

[0087] 15. A method of forming a coated component, the method comprising: applying a layer to a surface of a substrate, wherein the layer comprises the composition of any of the preceding clauses.

[0088] 16. A coated component, comprising: a substrate having a surface; and a thermal barrier coating on the surface; wherein the thermal barrier coating comprises a layer comprising the composition of any of the preceding clauses.

[0089] 17. A coated component, comprising: a substrate having a surface; and a thermal barrier coating on the surface; wherein the thermal barrier coating comprises a layer comprising yttria-rare earth doped zirconium oxide having a tetragonal structure, the layer having a thermal conductivity of 1.6 W / m-k to 2 W / m-k at 1000°C as measured by laser flash method according to ASTM E1461-13.

[0090] 18. The coated component of any of the preceding clauses, wherein the layer has an indentation work-of-fracture of 4 MPa-m 1 / 2 to 8 MPa-m 1 / 2 .

[0091] 19. The coated component of any of the preceding clauses, wherein the layer is substantially free of yttria-rare earth doped zirconium oxide having a cubic structure.

[0092] 20. The coated component of any of the preceding clauses, wherein the yttria-rare earth doped zirconium oxide having a tetragonal structure has the formula: Y a Ln b Ce x Zr 1-a-b-x O 2-δ , wherein Ln is a rare earth element or a mixture of rare earth elements included in substantially equal molar amounts; 0.01 < a < 0.05 1; 0.01 < b < 0.05 1; 0.05 < (a + b) < 0.07; 0 < x < 0.05; and 0 < δ < 0.05.

[0093] This written description uses examples to disclose the application, including the best mode, and also to enable any person skilled in the art to practice the application, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the application is defined by the claims, and can include other examples that occur to those skilled in the art. Such other examples are intended to fall within the scope of the claims if such examples result from a structural modification of a claimed element or if such examples result in insubstantial substitutions to the claimed elements of the structures and equivalents thereof.

Claims

1. A TBC composition, said TBC composition comprising: Yttrium oxide-rare earth-doped zirconium oxide with a tetragonal structure and the following formula: Y a Ln b This x Zr 1-a-b-x O 2-δ , In the formula, Ln is a mixture of rare earth elements; 0.01 ≤ a ≤ 0.051； 0.01 ≤ b ≤ 0.051, such that Y and each rare earth element are contained in the TBC composition in equal molar amounts; 0.05 ≤ (a + b) ≤ 0.07; 0 ≤ x ≤ 0.051； as well as 0 ≤ δ ≤ 0.

05.

2. The TBC composition according to claim 1, wherein, x is 0.

3. The TBC composition according to claim 1, wherein, x ranges from 0.01 to 0.

05.

4. The TBC composition according to claim 1, wherein, A value of a between 0.01 and 0.017 results in yttrium oxide-rare earth-doped zirconium oxide having the following formula: Y a Ln 1 b1 Ln 2 b2 Ln 3 b3 Ln 4 b4 Ce x Zr 1-a-b1-b2-b3-b4-x O 2-δ , In the formula, Ln 1 、Ln 2 、Ln 3 and Ln 4 Each represents a different rare earth element or a mixture of rare earth elements; 0.01 ≤ a ≤ 0.017； 0.01 ≤ b1 ≤ 0.017； 0.01 ≤ b2 ≤ 0.017； 0.01 ≤ b3 ≤ 0.017； 0 ≤ b4 ≤ 0.017； a = b1 = b2 = b3; 0.05 ≤ (a + b1 + b2 + b3 + b4) ≤ 0.07; 0 ≤ x ≤ 0.051； as well as 0.01 ≤ δ ≤ 0.

05.

5. The TBC composition according to claim 4, wherein, a = b1 = b2 = b3 = b4 = 0.

01.

6. The TBC composition according to claim 4, wherein, a = b1 = b2 = b3 = 0.012; and b4 is 0.

7. The TBC composition according to claim 4, wherein, a = b1 = b2 = b3 = b4 = 0.

012.

8. The TBC composition according to claim 4, wherein, a = b1 = b2 = b3 = 0.014; and b4 is 0.

9. The TBC composition according to claim 4, wherein, a = b1 = b2 = b3 = b4 = 0.

014.

10. The TBC composition according to claim 4, wherein, a = b1 = b2 = b3 = 0.017; and b4 is 0.

11. The TBC composition according to claim 1, wherein, Ln contains at least two of the following: La, Sm, Gd, Yb, Nd, Eu, Dy, Ho, Er, and Lu.

12. The TBC composition according to claim 1, wherein, Ln does not contain Tb and Pr.

13. The TBC composition according to claim 1, wherein, The thermal conductivity of the TBC composition at 1000°C, measured by laser scintillation according to ASTM E1461-13, is from 1.6 W / (m·K) to 2 W / (m·K).

14. The TBC composition according to claim 1, wherein, The TBC composition is selected from the following: Y 0.01 La 0.01 Gd 0.01 Yb 0.01 Sm 0.01 Zr 0.95 O2; Y 0.01 Sm 0.01 Yb 0.01 Gd 0.01 Nd 0.01 Zr 0.95 O 2-δ ; Y 0.012 Sm 0.012 Yb 0.012 Gd 0.012 Zr 0.93 Ce 0.02 O 2-δ ; Y 0.01 Sm 0.01 Ho 0.01 Gd 0.01 I 0.01 Zr 0.95 THE 2-δ ; Y 0.01 Sm 0.01 Dy 0.01 Gd 0.01 Er 0.01 Zr 0.95 O 2-δ ;as well as A mixture of them.

15. A method of forming a coated component, the method comprising: A layer is applied to the surface of a substrate, wherein the layer comprises the TBC composition of claim 1.

16. A coating component, the coating component comprising: A substrate with a surface; as well as Thermal barrier coating on the surface; The thermal barrier coating comprises a layer containing the TBC composition of claim 1.

17. The coated component according to claim 16, in, The thermal barrier coating comprises a layer of yttrium oxide-rare earth-doped zirconium oxide with a tetragonal structure, the layer having a thermal conductivity of 1.6 W / (m·k) to 2 W / (m·k) at 1000°C as measured by laser scintillation according to ASTM E1461-13.

18. The coated component according to claim 17, wherein, The indentation fracture toughness of the layer is 4 MPa·m. 1 / 2 Up to 8MPa·m 1 / 2 .

19. The coated component according to claim 17, wherein, The layer does not contain yttrium oxide-rare earth-doped zirconium oxide with a cubic structure.

20. The coated component according to claim 17, wherein, Yttrium oxide-rare earth-doped zirconium oxide with a tetragonal structure has the following formula: Y a Ln b This x Zr 1-a-b-x O 2-δ , In the formula, Ln is a rare earth element or a mixture of rare earth elements contained in equal molar amounts; 0.01 ≤ a ≤ 0.051； 0.01 ≤ b ≤ 0.051； 0.05 ≤ (a + b) ≤ 0.07; 0 ≤ x ≤ 0.05； as well as 0 ≤ δ ≤ 0.05.

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