Individual ceramic seals for gas turbines

Abstract

Various embodiments include gas turbine seals and methods of forming such seals. The method of forming the seal includes forming an independent ceramic seal for sealing in a gas turbine by applying a ceramic material to a substrate to form a ceramic layer, removing the substrate from the ceramic layer, and trimming the ceramic layer to define an independent ceramic seal. The method includes depositing particles of the ceramic material on a surface of a substrate in one of a molten or vapor state, and quenching the ceramic material to form a ceramic layer. The ceramic material includes yttria-stabilized zirconia having a t'tetragonal structure. A gas turbine including an independent ceramic seal is also disclosed.

Description

Background Art

[0001] The subject matter disclosed herein relates to turbines. In particular, the subject matter disclosed herein relates to seals in gas turbines.

[0002] The main gas flow path in a gas turbine typically includes the operating components of the compressor inlet, the compressor, the turbine, and the gas outflow portion. There are also auxiliary flows for cooling various heating components of the turbine. Generally speaking, the mixing of these flows and gas leakage from or into the gas flow path is harmful to turbine performance. Cooling flow leakage between turbine components generally leads to reduced power output and reduced efficiency. Leakage can be caused by thermal expansion of certain components and relative movement between components during operation of the gas turbine. Leakage of high-pressure cooling flow into the hot gas path may therefore cause harmful parasitic losses. Therefore, the overall efficiency can be improved by blocking the leakage location with a sealing component while providing cooling flow only as needed. Current gas turbine seals use a variety of different metal seal combinations and configurations to achieve such leakage control. For example, spline seals can be used between adjacent stator components in the ring assembly of a gas turbine.

[0003] Gas turbines and engines are selected to operate at temperatures above 1800°F, and often between 2200°F-2700°F. Therefore, many of the turbine components may be formed from advanced materials such as ceramic matrix composites (CMCs). Conventional metal seals made from exotic alloys such as Haynes 288, 214 are not suitable for applications exposed to temperatures above 1800°F due to accelerated failure from creep, oxidation, and high temperature corrosion. In addition, metal seals may react with CMC components at high temperatures.

[0004] Directionally solidified and / or single crystal nickel-based superalloys are commonly used to manufacture turbine blades for high temperature applications, but have been found to be difficult and expensive to manufacture into the thin seals required for these applications. In addition, seals of such materials will still require a thermal barrier layer formed over the bond coat to prevent oxidation when exposed to harsh environments at high temperatures. Therefore, the manufacture of seals comprising this three-layer composite structure is not scalable and is therefore not a viable option.

[0005] Therefore, improved seals, such as spline seals, are desired for use in gas turbine components that are exposed to harsh environments at high temperatures. In addition, improved seals for use in conjunction with gas turbine CMC components are also desired. Such seals should be high temperature resistant, wear resistant, and sufficiently flexible to provide adequate sealing with long component life. Summary of the invention

[0006] Various embodiments of the present disclosure include gas turbine seals and methods of forming such seals. According to an exemplary embodiment, a method of forming a stand-alone ceramic seal for sealing in a gas turbine is disclosed, the method comprising: applying a ceramic material on a substrate to form a ceramic layer; removing the substrate from the ceramic layer; and trimming the ceramic layer to define the stand-alone ceramic seal.

[0007] According to another exemplary embodiment, a self-contained ceramic seal for sealing a gas turbine hot gas path flow in a gas turbine is disclosed. The self-contained ceramic seal is composed of yttria-stabilized zirconia (YSZ).

[0008] According to another exemplary embodiment, a gas turbine is disclosed, comprising: a first arcuate component, the first arcuate component being adjacent to a second arcuate component, each arcuate component comprising one or more slots in an end surface; and a seal disposed in the slots of the first arcuate component and the slots of the second arcuate component. The seal comprises an independent ceramic seal composed of yttria-stabilized zirconia (YSZ) having a t'tetragonal structure.

[0009] Other purposes and advantages of the present disclosure will become apparent after reading the following detailed description and the appended claims with reference to the accompanying drawings. These and other features and improvements of the present application will become apparent to those of ordinary skill in the art after reading the following detailed description in conjunction with the several drawings and the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] These and other features of the present disclosure will be more readily understood from the following detailed description of various aspects of the present disclosure taken in conjunction with the accompanying drawings which depict various embodiments of the present disclosure, wherein:

[0011] Figure 1 shows a perspective, partially cut-away view of a known gas turbine;

[0012] Figure 2 Shown in a ring arrangement Figure 1 A perspective view of an exemplary arcuate component of a gas turbine:

[0013] Figure 3 A partial cross-sectional longitudinal view of a known turbine of a gas turbine is shown;

[0014] Figure 4 shows a schematic cross-sectional view of a portion of a turbine according to one or more embodiments shown or described herein;

[0015] Figure 5 Steps in a method of forming a standalone ceramic seal according to one or more embodiments shown or described herein are shown;

[0016] Figure 6 Steps in a method of forming a standalone ceramic seal according to one or more embodiments shown or described herein are shown;

[0017] Figure 7 Steps in a method of forming a standalone ceramic seal according to one or more embodiments shown or described herein are shown;

[0018] Figure 8 Steps in a method of forming a standalone ceramic seal according to one or more embodiments shown or described herein are shown; and

[0019] Fig. 9 Shown is a flow chart illustrating a method of forming a standalone ceramic seal according to one or more embodiments shown or described herein.

[0020] It should be noted that the drawings shown herein are not necessarily drawn to scale. The drawings are intended to depict only typical aspects of the disclosed embodiments, and therefore should not be considered to limit the scope of the disclosure. In the drawings, like numbers represent like elements between drawings. DETAILED DESCRIPTION

[0021] As described herein, the disclosed subject matter relates to turbines. In particular, the disclosed subject matter relates to seals within such turbines.

[0022] As shown in these figures, the "A" axis ( Figure 1 ) indicates an axial orientation (along the axis of the turbine rotor). As used herein, the terms "axial" and / or "axially" refer to the relative position / orientation of an object along an axis A that is substantially parallel to the axis of rotation of the turbine (particularly the rotor portion). As further used herein, the terms "radial" and / or "radially" refer to the relative position / orientation of an object along an axis (not shown) that is substantially perpendicular to axis A and intersects axis A at only one location. Additionally, the terms "circumferential" and / or "circumferentially" refer to the relative position / orientation of an object along a circumference (not shown) that surrounds axis A but does not intersect axis A at any location. It should also be understood that common numbering between the various figures represents substantially identical components in the figures.

[0023] See also Figure 1, which shows a perspective view of one embodiment of a gas turbine 10. In this embodiment, the gas turbine 10 includes a compressor inlet 12, a compressor 14, a plurality of combustors 16, a compressor discharge (not shown), a turbine 18 including a plurality of turbine blades 20, a rotor 22, and a gas outflow 24. The compressor inlet 12 supplies air to the compressor 14. The compressor 14 supplies compressed air to the plurality of combustors 16, where it is mixed with fuel. The combustion gases from the plurality of combustors 16 propel the turbine blades 20. The propulsed turbine blades 20 rotate the rotor 22. The casing 26 forms an outer casing surrounding the compressor inlet 14, the compressor 14, the plurality of combustors 16, the compressor discharge (not shown), the turbine 18, the turbine blades 20, the rotor 22, and the gas outflow 24. The gas turbine 10 is merely exemplary; the teachings of the present disclosure may be applied to a variety of gas turbines.

[0024] In one embodiment, the stationary components of each stage of the hot gas path (HGP) of the gas turbine 10 consist of a set of nozzles (stator airfoils) and a set of shrouds (static outer boundaries of the HGP at the rotor airfoils 20). Each set of nozzles and shrouds consists of a number of arcuate components arranged around the periphery of the hot gas path. See more specifically Figure 2 , which shows a perspective view of one embodiment of an annular arrangement 28 of a plurality of arcuate members 30 of a turbine 18 of a gas turbine 10. In the illustrated embodiment, the annular arrangement 28 as shown includes seven arcuate members 30, one of which has been removed for schematic illustration. Between each arcuate member 30 is an inter-segment gap. This segmented construction is necessary to manage thermal deformation and structural loads and to facilitate the manufacture and assembly of hardware.

[0025] Those skilled in the art will readily recognize that the annular arrangement 28 may have any number of arcuate components 30; the plurality of arcuate components 30 may have different shapes and sizes; may include metal and / or CMC components; and the plurality of arcuate components 30 may play different roles in the gas turbine 10. For example, the arcuate components in the turbine may include, but are not limited to, an outer shroud, an inner shroud, a nozzle block, and a diaphragm as described below.

[0026] See also Figure 3 , which shows a gas turbine 10 ( Figure 1) is a cross-sectional view of an embodiment of a turbine 18 of FIG. 2. In this embodiment, the casing 26 encloses a plurality of outer shrouds 34, an inner shroud 36, a plurality of nozzle blocks 38, a plurality of diaphragms 40, and turbine blades 20. Each of the outer shrouds 34, the inner shrouds 36, the nozzle blocks 38, and the diaphragms 40 forms a portion of the arcuate member 30. Each of the outer shrouds 34, the inner shrouds 36, the nozzle blocks 38, and the diaphragms 40 has one or more slots 32 on its side. In this embodiment, the plurality of outer shrouds 34 are connected to the casing 26; the inner shrouds 36 are connected to the plurality of outer shrouds 34; the plurality of nozzle blocks 38 are connected to the plurality of outer shrouds 34; and the plurality of diaphragms 40 are connected to the plurality of nozzle blocks 38. Those skilled in the art will readily recognize that many different arrangements and geometries of the arcuate members are possible. Alternative embodiments may include different arcuate member geometries, more arcuate members, or smaller arcuate members.

[0027] Cooling air is typically used to actively cool and / or clean static hot gas paths (flowing from the compressor of the gas turbine engine 10) from leaking through the inter-segment gaps 33 of each set of nozzles and shrouds. This leakage has a negative impact on overall engine performance and efficiency because it is parasitic to the thermodynamic cycle and has little to no beneficial effect on the cooling design of the hot HGP components. As previously mentioned, seals are typically incorporated into the inter-segment gaps of the static HGP components to reduce leakage. One or more slots 32 provide for the placement of such seals at the ends of each arcuate component 30. It should be understood that, according to various embodiments, the seals are typically straight, rectangular solid pieces of various types of configurations, and may include any type of planar seals, such as standard spline seals, solid seals, molded seals (e.g., dog-bone style), etc.

[0028] Go to Figure 4 , according to one embodiment, Figure 4 shows that it is usually similar to Figures 1 to 3 A partial longitudinal view of a cross section of a gas turbine 50 of the gas turbine 10 . Figure 4 shows a rough approximation Figure 2 0047] An exemplary end view of one of the plurality of arcuate components 30 and more specifically the first arcuate component 52 having a plurality of seals disposed therewith as disclosed herein.

[0029] like Figure 4 As shown, the first arcuate member 52 includes one or more slots 60 formed in the end surface 53 of the first arcuate member 52. The one or more slots 60 can be formed from multiple slot portions that are formed at an angle relative to each other and connected to each other, or as a single horizontally extending slot 60. More specifically, the one or more slots 60 can be formed from any number of intersecting or connected slot portions. Alternative configurations of the one or more slots 60 are contemplated.

[0030] exist Figure 4 In the illustrated embodiment of the gas turbine 50, the gas turbine 50 includes a seal 66 disposed in each of the one or more slots 60. It should be understood that the description of the seal 66 will be described below in conjunction with a single slot 60 of the arcuate member 52, but is equally applicable to one or more slots when one or more slots are disposed in adjacent arcuate members.

[0031] As previously mentioned, gas turbines and engines are selected to operate at temperatures above 1800°F. Therefore, the seal 66 must be suitable for use in harsh environments at such temperatures. Ceramic materials, specifically zirconium oxide-based materials, are widely used as high temperature thermal barrier coatings on gas turbine components such as blades, vanes, buckets, shrouds, etc. because they have high temperature performance, high refractoriness, low thermal conductivity, high toughness, low reactivity to glass dust, and relative ease of deposition by plasma spraying, flame spraying, and physical vapor deposition (PVD) techniques. For example, zirconium oxide is often used in a fully or partially stabilized form by blending with trace amounts of certain materials, such as oxides such as yttrium oxide (yttrium oxide), magnesium oxide, scandium, calcium oxide, or various rare earth oxides. For example, yttria-stabilized zirconia (YSZ) is often used. The t′ phase of yttria-stabilized zirconia (YSZ) is primarily formed and stabilized by quenching from a molten and / or vapor phase. Air plasma spraying (APS) is the most scalable process for forming these coatings commercially and has the advantages of relatively low equipment cost and ease of application and masking.

[0032] See now Figure 5-Figure 9 , which shows steps in a method of making one or more seals 66, which are described herein as stand-alone ceramic seals. The method is used to ultimately form a stand-alone t' phase of a yttria stabilized zirconia (YSZ) ceramic component that can be shaped and optionally trimmed for use as a seal 66, and more specifically for use as a gas turbine (such as Figure 1 Alternatively, the seal 66 may be used in power generation, aero engines, or any system operating in a thermally and chemically hostile environment.

[0033] See now Figure 5, which shows steps in a method of forming a separate seal (such as, seal 66 as described above). In one embodiment, the ceramic material is applied to a substantially smooth substrate by air plasma spraying (APS). Plasma technology is well known in the art. (See, for example, U.S. Pat. Nos. 5,332,598 (Kawasaki et al.); 5,047,612 (Savkar and Liliquist); U.S. Pat. No. 4,741,286 (Itoh et al.); and U.S. Pat. No. 4,455,470 (Klein et al.)). These references are instructive for various aspects of plasma spraying and are incorporated herein by reference. A person of ordinary skill in the field of plasma spraying is familiar with other details related to applying coatings by APS technology. Examples of other steps and process parameters include: cleaning the surface before deposition; sandblasting to remove oxides; substrate temperature; plasma spray parameters such as spray distance (gun to substrate); selecting the number of spray passes, powder feed rate, torch power, plasma gas selection; deposition angle, post-treatment of the applied coating; and the like. Any number of parameters are relevant to the effective deposition of ceramic layers from an APS system, including coating particle size and particle velocity. See, for example, an article by Berghaus et al. entitled "Injection Conditions and In-Flight Particle States in Suspension Plasma Spray of Alumina and Zirconia Nanoceramics," Proceedings of the 2005 International Thermal Spray Conference, held in Basel, Switzerland, May 2005. In addition, further information on the deposition of ceramic materials by air plasma spray techniques is discussed in commonly assigned U.S. Publication No. 2009 / 0162670A1, Yuk-Chiu, L. et al., "Methods for Applying Ceramic Coatings to Smooth Surfaces by Air Plasma Spray Techniques, and Related Articles," which is incorporated herein by reference in its entirety.

[0034] More specifically, in Figure 5In the embodiment of the present invention, a thermal spray system 80 and a substrate 82 on which a ceramic material is deposited are shown according to the present disclosure. In one embodiment, the thermal spray system 80 may include an air plasma spray (APS) system, a low pressure plasma spray system, a high velocity oxygen fuel thermal spray system, an electron beam physical vapor deposition system, or a vacuum plasma spray system. In one embodiment, the substrate 82 is composed of a metal, such as an aluminum-based alloy, a nickel-based alloy, an iron-based alloy, a cobalt-based alloy, etc. In one embodiment, the substrate 82 is composed of a pretreated metal. In one embodiment, the substrate 82 is composed of a non-metallic material, such as one or more of graphite, quartz, silicon carbide, etc. In the illustrated embodiment, the thermal spraying device 80 is a plasma spray system 84, which utilizes an electric arc (not shown) to generate a high temperature plasma gas 86 flow used as a spray heat source. The ceramic material 88 in powder form is carried in an inert gas flow (not shown) into the high temperature plasma gas 86 flow, where it is heated and pushed toward the surface 83 of the substrate 82 to form a layer 90 of the ceramic material 88. In the disclosed embodiment of the seal 66, the ceramic material 88 is yttria-stabilized zirconia (YSZ), wherein the crystal structure of zirconium dioxide is stabilized at room temperature by the addition of yttria. More specifically, in one embodiment, the ceramic material 86 is yttria-stabilized zirconia (YSZ) having a composition of about 3 wt% to about 8 wt% yttria. The thermal spraying apparatus 80 forms a layer 90 of the ceramic material 88 by melting a YSZ ceramic powder 88 in a stream of high temperature plasma gas 86 and then quenching the molten particles of the YSZ ceramic powder 88 onto a substrate surface 83, the temperature of the substrate surface being substantially lower than that of the molten ceramic material. The impact of the molten particles of the YSZ ceramic powder 88 on the substrate surface 83 and the extremely rapid solidification produce a metastable crystalline phase of yttria-stabilized zirconia called tetragonal (t′). This metastable phase is also referred to in the industry as the non-transformable phase because t' is considered stable below about 1200°C and retains significantly higher fracture toughness when compared to other phases of YSZ produced by other processing methods, compositions, and environmental phase instability mechanisms. The mechanical requirements of functional ceramic seals make the t' phase substantially the dominant phase.

[0035] like Figure 6 As best shown in FIG. 8 , a layer of ceramic material 90 is formed on a surface 83 of a substrate 82. Figure 7 and Figure 8As shown, in the next step, the substrate 82 is removed before further processing of the ceramic layer 90. Depending on the specific materials and processes, the substrate 82 can be removed using mechanical (e.g., cutting), thermal (e.g., burning) or chemical (e.g., dissolving in a solvent) methods or using a combination thereof. More specifically, after the layer 90 is formed, the ceramic layer 90 is recovered by removing the substrate 82. In one embodiment, the substrate 82 can be mechanically, chemically or thermally removed during this step, such as by cutting, leaching, dissolving, melting, oxidation, etching or any other similar method that provides removal of the substrate 82 without damaging the ceramic layer 90. In one embodiment, the substrate 82 is etched away in a suitable etching medium such as an acid or alkaline etchant. In one embodiment, the etchant medium can include a combination of nitric acid and hydrofluoric acid. In one embodiment, the substrate 82 is removed by rinsing with concentrated nitric acid (e.g., 67%, 50%, 40%, etc.). In other embodiments, concentrated hydrochloric acid can be used to remove the substrate 82. In one embodiment, the etchant medium is a mixture of nitric acid, hydrochloric acid and deionized water.

[0036] Still see Figure 7 and Figure 8 , the independent ceramic layer 90 from which the substrate 82 has been removed has been trimmed to a desired size, strength, density, surface texture and / or shape for use as an independent seal, and more specifically for forming the independent ceramic seal 66 ( Figure 4 ).like Figure 7 As best shown, the ceramic layer 90 is cut as indicated by dashed lines 92 to define a portion 94 that will define the seal 66 and one or more portions 96 that will be discarded. In one embodiment, the ceramic layer 90 is mechanically cut to substantially define the finished dimensions of the seal 66. More specifically, the ceramic layer 90 is cut so as to be formed into the desired shape for use as the seal 66.

[0037] like Figure 8As best shown, the surface 91 of the ceramic layer 90, and more specifically, the portion 94, is then finished, such as by grinding, honing, lapping and / or polishing, to produce the desired smoothness, roughness, size, etc. of the finished seal 66. Any conventional finishing step may be performed as long as the technique does not damage the ceramic layer 90. Non-limiting examples include sandblasting, manual sanding with fine abrasive paper, and mechanical polishing / finishing. The sandblasting itself can be performed in a variety of ways. As an example, a light particle blasting step can be implemented by directing a pressurized air stream containing silicon carbide particles on the surface of the ceramic layer 90 at a pressure of less than about 80 psi. In the illustrated embodiment, the portion 94 of the ceramic layer 90 is mechanically polished / finished using a vertical spindle and a polishing pad 98 and a suitable polishing medium, which rotates at a high speed as indicated by the directional arrows. In some specific embodiments, the thickness of the seal 66 is from about 0.05 mm to about 3.0 mm, and more specifically from about 0.125 mm to 2.5 mm in thickness. In one embodiment, the width and overall length of the seal 66 is substantially equal to the sealing slot 60 ( Figure 4 )’s width and overall length.

[0038] In an additional step, further post-processing steps may be performed to increase the strength of the ceramic layer 90. In one embodiment, depending on the density of the ceramic layer 90, the ceramic layer 90 may be densified into closed pores or infiltrated with a sintering precursor solution or slurry and sintered to closed pores to prevent leakage of the combusted gas phase and to add additional strength.

[0039] It should be understood that after removing the substrate 82, as described above in conjunction with Figure 6 As described above, the final finishing of the ceramic layer 90 (including Figure 7 ), such as Figure 8 Surface finishing and shaping as described in, and / or Fig. 9 The additional post-processing steps described in may be performed in any order to obtain the desired resulting free-standing ceramic seal 66 .

[0040] Fig. 9 1 is a flow chart showing a method 100 of forming a seal in a gas turbine according to various figures. The method may include the following processes:

[0041] Process P1 shown at 102 includes placing a ceramic material on a substrate to form a ceramic layer. The ceramic material comprises yttria-stabilized zirconia (YSZ) having a t′-phase tetragonal structure. In one embodiment, the substrate comprises a metal, such as an austenitic nickel-chromium superalloy, more specifically

[0042] Process P2, shown at 104, includes removing the substrate from the ceramic layer. Removal of the substrate may be accomplished using any of mechanical methods (e.g., cutting), thermal methods (e.g., burning), plasma-based methods (e.g., plasma etching), or chemical methods (e.g., dissolving in a solvent), or a combination thereof.

[0043] In process P3 shown at 106, ceramic layer 90, from which substrate 82 has been removed, has been trimmed to a desired size, strength, density, surface texture, and / or shape for use as a stand-alone seal, and more specifically for forming stand-alone ceramic seal 66 ( Figure 4 ). In this step, the trimming of the ceramic layer 90 may include but is not limited to the following steps: Figure 7 The cutting, such as Figure 8 The surface finishing described above, and / or additional post-processing steps as described above, are performed to obtain the desired resulting seal 66. After the seal 66 is manufactured, in one embodiment, the seal 66 is applied to a turbine (e.g., a gas turbine 10, Figure 1 ), wherein application includes inserting the seal 66 into the slot 60.

[0044] The primary requirements for high refractive index and toughness of the individual seal components, more specifically seal 66, are provided by the t' phase of the yttria-stabilized zirconia from which it is made, which is achieved by a quench-forming process of thermal spraying on a large area substrate. The resulting individual seal 66 exhibits high refractive index (thermal stability), high toughness (wear and impact resistance), and the ability to be manufactured to a variety of thicknesses while providing reduced manufacturing costs.

[0045] It should be understood that in the methods shown and described herein, other processes may be performed without being shown, and the order of the processes may be rearranged according to various embodiments. In addition, intermediate processes may be performed between one or more of the processes. The process flows shown and described herein should not be construed as limitations on the various embodiments.

[0046] The terms used herein are only used for the purpose of describing specific embodiments and are not intended to limit the present disclosure. As used herein, the singular forms "a", "an" and "the" are intended to also include plural forms, unless the context clearly states otherwise. It will be further understood that when used in the specification, the terms "include" and / or "comprise" specify the presence of stated features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or their groups.

[0047] This written description uses examples to disclose the present disclosure, including the best mode, and also to enable any person skilled in the art to practice the present disclosure, including making and using any device or system and performing any combined method. The patentable scope of the present disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that are not substantially different from the literal language of the claims.

Claims

1. A method of forming a stand-alone ceramic seal for sealing in a gas turbine, comprising: applying a ceramic material on a substrate to form a ceramic layer; removing the substrate from the ceramic layer; as well as trimming the ceramic layer to define the independent ceramic seal, wherein trimming the ceramic layer to define the independent ceramic seal comprises: performing at least one of cutting, polishing, lapping, honing, sintering to close the pores, and infiltrating with a sintering precursor prior to sintering to close the pores; or Wherein trimming the ceramic layer to define the independent ceramic seal includes trimming to one or more of a desired size, strength, density, surface texture, and shape to function as the independent ceramic seal.

2. The method of claim 1, wherein the substrate is composed of one of a metal or a metal alloy.

3. The method according to claim 1, wherein the step of applying a ceramic material on a substrate to form a ceramic layer comprises depositing particles of the ceramic material on the surface of the substrate in one of a molten or vapor state, and quenching the ceramic material to form the ceramic layer.

4. The method of claim 1, wherein the step of applying a ceramic material on a substrate to form a ceramic layer comprises applying using a thermal spray deposition process.

5. A method according to claim 4, wherein the ceramic material forming the ceramic layer has been applied to the substrate by air plasma spraying (APS) technology.

6. The method of claim 1, wherein the ceramic material comprises yttria-stabilized zirconia.

7. The method of claim 6, wherein the yttria-stabilized zirconia has primarily a t'-tetragonal structure.

8. The method of claim 6, wherein the yttria-stabilized zirconia (YSZ) comprises 3 wt% to 8 wt% yttria.

9. The method of claim 1, wherein removing the substrate comprises removing using at least one of a mechanical method, a thermal method, and a chemical method.

10. The method of claim 1, wherein removing the substrate comprises removing by etching the substrate away using one of an acid or a base.

11. The method of claim 1 further comprising a post-processing step to increase the strength of the ceramic layer.

12. An independent ceramic seal for sealing a hot gas flow path of a gas turbine in a gas turbine obtained by the method according to any one of claims 1 to 11, wherein the independent ceramic seal is composed of yttria-stabilized zirconia (YSZ).

13. The stand-alone ceramic seal of claim 12, wherein the yttria-stabilized zirconia (YSZ) has a t'-tetragonal structure.

14. The self-contained ceramic seal of claim 13, wherein the yttria-stabilized zirconia (YSZ) comprises 3 wt% to 8 wt% yttria.

15. The independent ceramic seal of claim 12, wherein the independent ceramic seal is one of a spline seal, a solid seal, or a molded seal.

16. The independent ceramic seal of claim 12, wherein the independent ceramic seal has a thickness of 0.05 mm to 3.0 mm.

17. A gas turbine comprising: a first arcuate member adjacent to a second arcuate member, each arcuate member including one or more slots in an end surface; and A seal, the seal being disposed in the slot of the first arcuate component and the slot of the second arcuate component, the seal comprising: An independent ceramic seal, obtained according to the method according to any one of claims 1 to 11, composed of yttria-stabilized zirconia (YSZ) having a t'-tetragonal structure.

18. The gas turbine of claim 17, wherein the independent ceramic seal is one of a spline seal, a solid seal, or a molded seal.

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