Coke reduction coating component used in gas turbine engine

Abstract

A coated component for use in a gas turbine engine to reduce coke is provided. The coated component includes a substrate and a catalytic coating. The catalytic coating has a first layer in contact with the substrate, the first layer comprising a first ceramic material and a first noble metal; a second layer in contact with the first layer, the second layer comprising a second ceramic material and a second noble metal; and a third layer in contact with the second layer, the third layer comprising a third ceramic material and a third noble metal. The first layer has a plurality of particles having an average diameter, and the first layer has a volume percent porosity. The second layer has a plurality of particles having a bimodal distribution, and the second layer has a volume percent porosity. The third layer has a plurality of particles having an average diameter, and the third layer has a volume percent porosity.

Description

TECHNICAL FIELD

[0001] The present invention relates to a coated component comprising a substrate and a catalytic coating, and to a method of using the coated component to reduce coke, for example in a gas turbine engine for an aircraft. BACKGROUND

[0002] Gas turbine engines include surfaces that come into contact with hydrocarbon fluids, such as fuel and lubricating oil. When these surfaces are exposed to the hydrocarbon fluids at elevated temperatures, carbonaceous deposits (also known as coke) can form on the surfaces, resulting in coke adhering to the surfaces that come into contact with the fuel or oil and accumulating deposits on the surfaces that come into contact with the fuel or oil. SUMMARY

[0003] The present invention provides a coated component for reducing coke in a gas turbine engine, the coated component comprising:

[0004] a substrate; and

[0005] a catalytic coating, the catalytic coating comprising:

[0006] a first layer in contact with the substrate, the first layer comprising a first ceramic material and a first noble metal, wherein the first layer has a volume percent porosity;

[0007] a second layer in contact with the first layer, the second layer comprising a second ceramic material and a second noble metal, wherein the second layer has a plurality of particles having a multimodal particle size distribution, the volume percent porosity of the second layer is greater than the volume percent porosity of the first layer; and

[0008] a third layer in contact with the second layer, the third layer comprising a third ceramic material and a third noble metal, wherein the volume percent porosity of the third layer is less than the volume percent porosity of the second layer.

[0009] Preferably, the first layer has a plurality of particles having an average diameter ranging from 0.5 pm to 1 pm, the volume percent porosity of the first layer ranges from 10% to 30%,

[0010] the second layer has a bimodal particle size distribution, wherein the bimodal particle size distribution has a first mode diameter ranging from 0.5 pm to 2 pm and a second mode diameter ranging from 4 pm to 20 pm, the volume percent porosity of the second layer ranges from 20% to 60%, and

[0011] the third layer has a plurality of particles having an average diameter ranging from 0.5 pm to 2 pm, the volume percent porosity of the third layer ranges from 5% to 30%.

[0012] Preferably, the first ceramic material, the second ceramic material, and the third ceramic material have the same chemical composition.

[0013] Preferably, the thickness of the first layer ranges from 2.5 pm to 15 pm.

[0014] Preferably, the thickness of the second layer ranges from 25 pm to 50 pm.

[0015] Preferably, the thickness of the third layer ranges from 2.5 pm to 15 pm.

[0016] Preferably, each layer comprises a binder.

[0017] Preferably, each layer comprises a binder comprising silica.

[0018] Preferably, the coating of the coated component has a coating mass loss of less than 7 wt% when the coated component is exposed to a hot air jet having a temperature of 1100 degrees Fahrenheit and a velocity of 104 L / min for one hour.

[0019] Preferably, the first ceramic material, the second ceramic material, and the third ceramic material are each independently selected from the group consisting of metal oxides of formula (1) A x E y L z MO u wherein A is one or more alkaline earth elements selected from the group consisting of magnesium, calcium, strontium, and barium; x ranges from 0 to 1 ; E is one or more alkali metals selected from the group consisting of lithium, sodium, and potassium; y ranges from 0 to 1 ; L is one or more lanthanide elements selected from the group consisting of lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, ytterbium, and lutetium; z ranges from 0 to 1 ; M is one or more elements selected from the group consisting of titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, tantalum, tungsten, rhenium, iridium, platinum, gold, and bismuth; O is oxygen; and u ranges from 0.95 to 6.

[0020] Preferably, the coated component is an aircraft component.

[0021] Preferably, the coated component is a gas turbine engine component.

[0022] Preferably, the coated component is a Venturi surface, a fuel nozzle, a fuel circuit component, or an oil lubrication circuit component.

[0023] Preferably, the substrate is a metal substrate, a ceramic substrate, a metal substrate coated with a ceramic layer, or a ceramic substrate coated with a metal layer.

[0024] Preferably, the substrate is a metal substrate selected from the group consisting of a iron-based alloy, a nickel-based alloy, a cobalt-based alloy, an alloy containing cobalt and chromium, an alloy containing platinum and aluminum, an alloy containing nickel and aluminum, and an alloy containing nickel, chromium, aluminum, and yttrium.

[0025] Preferably, the substrate is a metal substrate coated with a ceramic layer, the ceramic layer being a thermal barrier coating.

[0026] The present invention also provides a method of oxidizing coke, the method comprising:

[0027] contacting the coke with the coated part of claim 1 at a temperature ranging from 300 degrees Fahrenheit to 1100 degrees Fahrenheit.

[0028] The present invention also provides a method of manufacturing the coated part of claim 1, the method comprising:

[0029] spraying particles of a first ceramic material and a first noble metal on the substrate, wherein the particles of the first ceramic material and the first noble metal have an average particle size ranging from 0.5 μιη to 1 μιη;

[0030] spraying particles of a second ceramic material and a second noble metal, wherein the particles of the second ceramic material and the second noble metal have a first plurality of particles having an average particle size ranging from 0.5 μιη to 1 μιη and a second plurality of particles having an average particle size ranging from 4 μιη to 20 μιη;

[0031] spraying particles of a third ceramic material and a third noble metal, wherein the particles of the third ceramic material and the third noble metal have an average particle size ranging from 0.5 μιη to 2 μιη; and

[0032] sintering at least some of the particles of the third ceramic material and the third noble metal at a temperature ranging from 1500 degrees Fahrenheit to 2000 degrees Fahrenheit.

[0033] Preferably, the sintering fuses the particles of the first ceramic material and the first noble metal to form a plurality of particles having an average diameter ranging from 0.5 μιη to 1 μιη in the first layer of the catalytic coating; the sintering fuses the particles of the second ceramic material and the second noble metal to form a plurality of particles having a bimodal distribution in the second layer of the catalytic coating, wherein the bimodal distribution has a first mode diameter ranging from 0.5 μιη to 2 μιη and a second mode diameter ranging from 4 μιη to 20 μιη; and the sintering fuses the particles of the third ceramic material and the third noble metal to form a plurality of particles having an average diameter ranging from 0.5 μιη to 2 μιη in the third layer of the catalytic coating.

[0034] Preferably, the sintering includes applying heat to the catalytic coating and cooling the substrate on a side opposite the catalytic coating. BRIEF DESCRIPTION OF DRAWINGS

[0035] The features and advantages of the present disclosure will be apparent from the following description of various exemplary embodiments, taken in conjunction with the accompanying drawings, which illustrate, by way of example, the principles of the application. The same reference numbers in different drawings identify the same, functionally similar, and / or structurally similar elements.

[0036] Figure 1 Schematic view of an aircraft having a gas turbine engine according to one embodiment of the disclosure.

[0037] Figure 2 Is a cross-sectional view of the gas turbine engine of the aircraft shown in Figure 1 Figure 2

[0038] Figure 3 Is a cross-sectional view of the combustor of the gas turbine engine shown in Figure 2 Figure 3 Figure 2

[0039] Figure 4 Is a cross-sectional view of the mixer assembly of the combustor shown in Figure 3 Figure 4 Figure 3

[0040] Figure 5 Is a cross-sectional view of the combustor of the gas turbine engine shown in Figure 2

[0041] Figure 6 Is a cross-sectional view of the mixer assembly of the combustor shown in Figure 5 Figure 6 Figure 5

[0042] Figure 7 Is a cross-sectional view of a catalytic coating applied to the surface of a venturi and aft heat shield.

[0043] Figure 8A Is a cross-sectional view of a catalytic coating applied to a substrate.

[0044] Figure 8B Is a cross-sectional view of a catalytic coating applied to a substrate having a ceramic coating.

[0045] Figure 9 Is a cross-sectional view of a catalytic coating having one or more layers.

[0046] Figure 10A Shows the surface of a coating after air impact testing.

[0047] Figure 10B Shows the surface of a coating after air impact testing. DETAILED DESCRIPTION

[0048] ​​​​​​​​​​​​The features, advantages and embodiments of the present disclosure are set forth or apparent by considering the following detailed description, drawings and claims. Furthermore, the following detailed description is exemplary and is intended to provide further explanation without limiting the scope of the present disclosure as claimed.

[0049] Various embodiments will be discussed in detail below. Although specific embodiments are discussed, this is for illustrative purposes only. Those skilled in the relevant art will recognize that other components and configurations may be used without departing from the present disclosure.

[0050] The terms "fore" and "aft" refer to relative positions within a gas turbine engine or vehicle and to the normal operating attitude of the gas turbine engine or vehicle. For example, in the context of a gas turbine engine, the front position refers to the position closer to the engine inlet, and the aft position refers to the position closer to the engine nozzle or exhaust.

[0051] The terms "upstream" and "downstream" refer to the relative directions of fluid flow within a fluid channel. For example, "upstream" refers to the direction from which a fluid is flowing, while "downstream" refers to the direction to which a fluid is flowing. The term "fluid" can refer to a gas or a liquid. The term "fluid communication" refers to the ability of a fluid to establish a connection between designated areas.

[0052] The terms “coupled,” “fixed,” “attached,” “connected,” and the like refer to both direct coupling, fixing, attachment, or connection as well as indirect coupling, fixing, attachment, or connection through one or more intermediate components or features, unless otherwise specified herein.

[0053] The term "noble metals" refers to the elements rhenium, ruthenium, rhodium, palladium, silver, osmium, iridium, platinum and gold.

[0054] As used herein, an alloy is "based on" a particular element among all elements contained in the alloy when that particular element is present in the alloy in the highest weight percentage relative to the total weight of the alloy. For example, an iron-based alloy has a higher weight percentage of iron than any other single element present in the alloy.

[0055] As used herein, a region of material is a connected subset of material having a generally uniform composition.

[0056] As used herein, a region of a material may comprise one or more "grains" of generally uniform composition and structure. A crystallite is an example of a grain. The average particle size of a material can be determined, for example, by electron microscopy. The diameter of a particle is the diameter of the smallest sphere that encloses the particle.

[0057] As used herein, the "mode diameter" of a plurality of particles having a multimodal particle size distribution is the diameter corresponding to the peak in the probability density function for the diameters of the plurality of particles.A bimodal particle size distribution is an example of a multimodal particle size distribution.

[0058] As used herein, coke is selectively oxidized by a catalytic coating in the presence of a hydrocarbon fuel if the reaction rate of the coke oxidation through the catalytic coating is higher than the reaction rate of the hydrocarbon fuel through the catalytic coating.

[0059] As used herein, "flash sintering" refers to a process for sintering a coating wherein the coating has a thermal gradient across the thickness of the coating. In certain embodiments, flash sintering can be performed by heating one side of the coating and cooling the other side of the coating. In certain embodiments, flash sintering can be performed by heating one side of the coating for a sufficiently short time that a uniform temperature is not achieved across the thickness of the coating, and this heating step can be repeated, for example, for from two to ten heating cycles. Any disclosed sintering step described in this disclosure can be a flash sintering step.

[0060] The singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise.

[0061] Approximate language, as used throughout the specification and claims, is used to modify any quantitative expression that can be allowed to vary without causing a change in the basic function to which it is associated. Therefore, a value modified by one or more terms such as "approximately," "approximately," and "substantially" is not limited to the precise value specified. In at least some cases, approximate language may correspond to the precision of an instrument used to measure the value, or the precision of a method or machine used to construct or manufacture a component and / or system. For example, approximate language may refer to within a margin of 1%, 2%, 4%, 10%, 15%, or 20% of a single value, a range of values, and / or an endpoint of a range defining a value.

[0062] Here, as well as throughout the specification and claims, range limitations may be combined and / or interchanged. Such ranges are defined and include all subranges contained therein unless context or language indicates otherwise. For example, all ranges disclosed herein are inclusive of the endpoints, and the endpoints are independently combinable with each other.

[0063] As mentioned above, at elevated temperatures, coke deposits can occur on surfaces of gas turbine engines that are exposed to hydrocarbon fluids, such as fuel and lubricating oil. Fuel nozzles and swirlers (collectively, the mixer assembly) used in gas turbine engine combustors include such surfaces. During engine operation, the fuel nozzle aft heat shield (FN-AHS) protects the fuel nozzles from the hot combustion gases. The surfaces of the FN-AHS and other surfaces of the mixer assembly (such as the fuel nozzle venturi) are exposed to hydrocarbon fluids, such as fuel. Gas turbine engine operation, particularly the continuous operation of aircraft gas turbine engines in cruise mode, can result in significant accumulation of coke and / or partially burned fuel deposits on the exposed surfaces of the FN-AHS and the mixer assembly.

[0064] Coke can accumulate to considerable thicknesses, and large pieces of coke can break off from these surfaces as internal objects, which can cause significant damage to components downstream of the fuel nozzles (hot gas path components). Some of these components have thermal barrier coatings (TBCs). The resulting internal object impact damage (DoD) can cause spalling of the thermal barrier coating and can reduce the durability of components such as burners, nozzles, shrouds, and airfoils. Coke deposition can be reduced or eliminated by using a catalytic coating that can catalyze degradation reactions of coke (e.g., coke oxidation). For example, coke oxidation can convert solid coke deposits into gaseous reaction products because coke oxidation can include the reaction of carbon with diatomic oxygen to form reaction products such as carbon monoxide and carbon dioxide. In the absence of a catalytic coating that can catalyze degradation reactions of coke, coke can accumulate on surfaces and reduce the performance of systems and components.

[0065] Disclosed herein are catalytic coatings that can be applied to various surfaces and components to reduce the accumulation of coke thereon. The catalytic coating comprises three layers, each layer having a ceramic material and a precious metal, such that the catalytic coating is catalytically active. The volume percent porosity and particle size of each layer are tailored to improve the durability of the catalytic coating when the catalytic coating is applied to a substrate (such as a surface or portion of a component). Some non-limiting examples of suitable surfaces and components include aircraft components, gas turbine engine components, lubricating oil system components, fuel channel components, fuel circuit components, fuel nozzles (such as venturi surfaces on fuel nozzles), mixer assembly components, and rear heat shields. The gas turbine can be an aircraft gas turbine, or it can be, for example, an onshore turbine for a power plant or an offshore gas turbine engine for a ship. Some of these components will be described in more detail below.

[0066] Figure 1An aircraft 20 is shown in which various embodiments may be implemented. Aircraft 20 includes a fuselage 22, wings 24 attached to fuselage 22, and an empennage 26. Aircraft 20 also includes a propulsion system that can generate the propulsive thrust required to propel aircraft 20 in flight, during taxiing operations, and the like. Figure 2 The aircraft 20 shown in FIG. 1 includes a propulsion system comprising a pair of engines 100. In this embodiment, each engine 100 is attached to one of the wings 24 via a pylon 28 in an underwing configuration. Although the engines 100 are Figure 1 2 as attached to the wing 24 in an underwing configuration, but in other embodiments, the engine 100 may have alternative configurations and be coupled to other portions of the aircraft 20. For example, the engine 100 may additionally or alternatively include one or more aspects that are coupled to other portions of the aircraft 20, such as the tail 26 and the fuselage 22.

[0067] As will be referenced below Figure 2 Further describing, Figure 1 The engines 100 shown in FIG. 1 are gas turbine engines, each of which is capable of selectively generating propulsive thrust for the aircraft 20. The amount of propulsive thrust is based at least in part on the amount of propulsive thrust generated by the fuel system 150 (see FIG. Figure 2 ) is controlled by the volume of fuel supplied to the engine 100 (e.g., a gas turbine engine). In the embodiment discussed herein, the aviation turbine fuel is a combustible hydrocarbon liquid fuel, such as kerosene fuel with a desired carbon number, synthetic aviation fuel, biofuel, biodiesel, ethanol, bioalcohol, etc. The fuel is stored in a fuel tank 151 of the fuel system 150. Figure 1 As shown, at least a portion of fuel tank 151 is located in each wing 24, and a portion of fuel tank 151 is located in fuselage 22 between wings 24. However, fuel tank 151 may be located in other suitable locations in fuselage 22 or wings 24. Fuel tank 151 may also be located entirely within fuselage 22 or wings 24. Fuel tank 151 may also be a plurality of separate tanks rather than a single, integral body, for example, two tanks, each located within a respective wing 24.

[0068] Although Figure 1The aircraft 20 shown in FIG is an airplane, but the embodiments described herein may also be applicable to other aircraft 20, including, for example, helicopters and unmanned aerial vehicles (UAVs). The aircraft discussed herein are fixed-wing aircraft or rotary-wing aircraft that generate lift through aerodynamic forces acting on, for example, fixed wings (e.g., wings 24) or rotary wings (e.g., the rotors of a helicopter) and are heavier-than-air aircraft, rather than lighter-than-air aircraft (e.g., airships). Furthermore, although not described herein, in other embodiments, the gas turbine engine may be any other suitable type of gas turbine engine, such as an industrial gas turbine engine integrated into a power generation system, a marine gas turbine engine, etc.

[0069] Figure 2 yes Figure 1 1 is a schematic cross-sectional view of one of the engines 100 used in a propulsion system for an aircraft 20 . Figure 2 The cross-sectional view is along Figure 1 The line 2-2 in the interception. Figure 2 In the embodiment shown in FIG, the engine 100 is a high bypass engine. The engine 100 has an axial direction A (extending parallel to the longitudinal centerline axis 101, Figure 2 ), radial direction R, and circumferential direction. Figure 2 The fan section 102 and the turbine engine 104 are arranged downstream of the fan section 102 .

[0070] Figure 2 The turbine engine 104 shown in FIG includes a compressor section 103, a combustion section 114, and a turbine section 115 in a serial flow relationship. The turbine engine 104 is substantially enclosed in a casing 106, which is substantially tubular and defines a core inlet 108. In the embodiment shown, the core inlet 108 is annular. Figure 2As shown, compressor section 103 includes a supercharger or low-pressure (LP) compressor 110, followed downstream by a high-pressure (HP) compressor 112. A combustion section 114 is located downstream of compressor section 103. A turbine section 115 is located downstream of combustion section 114 and includes a high-pressure (HP) turbine 116, followed downstream by a low-pressure (LP) turbine 118. Turbine engine 104 also includes an exhaust nozzle section 120, located downstream of turbine section 115, a high-pressure (HP) shaft 122 or spool, and a low-pressure (LP) shaft 124. HP shaft 122 drivingly connects HP turbine 116 to HP compressor 112. HP turbine 116 and HP compressor 112 rotate in unison via HP shaft 122. LP shaft 124 drivingly connects LP turbine 118 to LP compressor 110. LP turbine 118 and LP compressor 110 rotate in unison via LP shaft 124. The compressor section 103 , the combustion section 114 , the turbine section 115 , and the exhaust jet nozzle section 120 collectively define a core air flow path 121 through which core air 139 flows.

[0071] Figure 2 The fan section 102 shown in FIG includes a fan 126 (eg, a variable pitch fan) having a plurality of fan blades 128 coupled to a disk 130 in a spaced-apart manner. Figure 2 As shown, the fan blades 128 extend outwardly from the disk 130 generally in a radial direction R. In the case of a variable pitch fan, a plurality of fan blades 128 are rotatable about a pitch axis P relative to the disk 130 by means of the fan blades 128 being operably coupled to a brake member 131, the actuating member 131 being configured to collectively and uniformly change the pitch of the fan blades 128. The fan blades 128, disk 130, and brake member 131 are rotatable about the longitudinal centerline axis 101 by a fan shaft 133, which is powered by the LP shaft 124 through a power gearbox (also referred to as a gearbox assembly 135). In this manner, the fan 126 is drivingly coupled to and powered by the turbine engine 104, the engine 100 being an indirectly driven engine. The gearbox assembly 135 is schematically shown as Figure 3 The gearbox assembly 135 may be a reduction gearbox assembly for adjusting the rotational speed of the fan shaft 133 , thereby adjusting the rotational speed of the fan 126 relative to the LP shaft 124 when power is transmitted from the low pressure shaft 124 to the fan shaft 133 .

[0072] Still refer to Figure 2In the exemplary embodiment of the present invention, the disk 130 is covered by a fan hub 132 having an aerodynamic profile to facilitate airflow through the plurality of fan blades 128. In addition, the fan section 102 also includes an annular fan casing or nacelle 134 that circumferentially surrounds the fan 126 and at least a portion of the turbine engine 104. The nacelle 134 is supported relative to the turbine engine 104 by a plurality of outlet guide vanes 136 that are circumferentially spaced about the nacelle 134 and the turbine engine 104. In addition, a downstream section 138 of the nacelle 134 extends over an exterior portion of the turbine engine 104 and, together with the outer casing 106, defines a bypass airflow passage 140 therebetween.

[0073] During operation of engine 100, a volume of air enters a turbine engine (e.g., engine 100) through cowling 134 or engine inlet 129 of fan section 102. As the volume of air passes through fan blades 128, a first portion of the air (also referred to as bypass air 137) is directed into bypass airflow passage 140, while a second portion of the air (also referred to as core air 139) is directed into an upstream section of core airflow path 121 through core inlet 108 of LP compressor 110. The ratio between bypass air 137 and core air 139 is generally referred to as the bypass ratio. The pressure of core air 139 is then increased in compressor section 103, more specifically, LP compressor 110, generating compressed air 141. Compressed air 141 is then directed through HP compressor 112, where it is further compressed and enters combustion section 114, where it is mixed with fuel and combusted to generate combustion gases 143.

[0074] Combustion gases 143 are directed into HP turbine 116 and expand therethrough, where a portion of the thermal or kinetic energy from combustion gases 143 is extracted via HP turbine stator blades and one or more stages of HP turbine rotor blades coupled to HP shaft 122. This causes HP shaft 122 to rotate, thereby supporting the operation of HP compressor 112 (a self-sustaining cycle). In this manner, combustion gases 143 perform work on HP turbine 116. Combustion gases 143 are then directed into LP turbine 118 and expand therethrough. Here, a second portion of the thermal or kinetic energy is extracted from combustion gases 143 via LP turbine stator blades and one or more stages of LP turbine rotor blades coupled to LP shaft 124. This causes LP shaft 124 to rotate, thereby supporting the operation of LP compressor 110 (a self-sustaining cycle) and the rotation of fan 126 via gearbox assembly 135. In this manner, combustion gases 143 perform work on LP turbine 118.

[0075] The combustion gases 143 are then directed through the exhaust nozzle section 120 of the turbine engine 104 to provide propulsive thrust. Simultaneously, bypass air 137 is directed through a bypass airflow passage 140 and then exhausted from the fan nozzle exhaust section of the engine 100, also providing propulsive thrust. HP turbine 116, LP turbine 118, and exhaust nozzle section 120 at least partially define a hot gas path for directing the combustion gases 143 through the turbine engine 104.

[0076] The engine 100 can operate in conjunction with and receive a fuel flow from a fuel system 150. The fuel system 150 includes a fuel delivery assembly 153 that provides a fuel flow from a fuel tank 151 to the engine 100, and more specifically, to a plurality of fuel injectors 200 that inject fuel into the combustors 300 of the combustion section 114 (see FIG. Figure 4 , which will be discussed further below).

[0077] Components of the fuel system 150, more specifically the fuel tank 151, are one example of a fuel source that provides fuel to the fuel injectors 200, as discussed in greater detail below. A fuel delivery assembly 153 includes pipes, tubes, conduits, and the like that fluidly connect the various components of the fuel system 150 to the engine 100. The fuel tank 151 is configured to store hydrocarbon fuel, which is supplied from the fuel tank 151 to the fuel delivery assembly 153. The fuel delivery assembly 153 is configured to deliver hydrocarbon fuel between the fuel tank 151 and the engine 100, thereby providing a flow path (fluid passage) from the fuel tank 151 to the engine 100.

[0078] Fuel system 150 includes at least one fuel pump fluidly connected to fuel delivery assembly 153 to direct the flow of fuel through fuel delivery assembly 153 to engine 100. One such pump is a main fuel pump 155. Main fuel pump 155 is a high-pressure pump that is the primary source of pressure increase in fuel delivery assembly 153 between fuel tank 151 and engine 100. Main fuel pump 155 can be configured to increase the pressure in fuel delivery assembly 153 to a pressure that exceeds the pressure within combustion chamber 302 of combustor 300.

[0079] Fuel system 150 also includes a fuel metering unit 157 in fluid communication with fuel delivery assembly 153. Any suitable fuel metering unit 157 can be used, including, for example, a metering valve. Fuel metering unit 157 is located downstream of main fuel pump 155 and upstream of fuel manifold 159, which is configured to distribute fuel to fuel injectors 200. Fuel system 150 is configured to provide fuel to fuel metering unit 157, which is configured to receive fuel from fuel tank 151. Fuel metering unit 157 is also configured to provide a desired flow of fuel to engine 100. More specifically, fuel metering unit 157 is configured to meter fuel and provide a desired volume of fuel, for example, at a desired flow rate, to fuel manifold 159 of engine 100. Fuel manifold 159 is fluidly connected to fuel injectors 200 and distributes (provides) the received fuel to a plurality of fuel injectors 200, where the fuel is injected into combustion chambers 302 and combusted. Adjusting the fuel metering unit 157 may vary the volume of fuel provided to the combustion chamber 302 , thereby varying the amount of propulsive thrust generated by the engine 100 to propel the aircraft 20 .

[0080] The engine 100 also includes various accessory systems to assist in the operation of the engine 100 and / or an aircraft including the engine 100. For example, the engine 100 may include a main lubrication system 162, a compressor cooling air (CCA) system 164, an active thermal clearance control (ATCC) system 166, and a generator lubrication system 168. Figure 2 Each of these systems is schematically depicted in FIG. Main lubrication system 162 is configured to provide lubricant to various bearings and gear meshes, such as in the compressor section, turbine section, HP spool 122, and LP spool 124. The lubricant provided by main lubrication system 162 can extend the service life of these components and can remove a certain amount of heat from these components through the use of one or more heat exchangers. Compressor cooling air (CCA) system 164 provides air from one or both of HP compressor 112 or LP compressor 110 to one or both of HP turbine 116 or LP turbine 118. Active thermal clearance control (ATCC) system 166 is used to minimize clearances between the turbine blade tips and the casing wall as casing temperatures vary during a mission. Generator lubrication system 168 provides lubrication and cooling / heat removal for an electric generator (not shown). The electric generator can provide electrical power, for example, to a starter motor for engine 100 and / or various other electrical components of engine 100 and / or an aircraft including engine 100. For example, the lubrication systems for the engine 100 (eg, the main lubrication system 162 and the generator lubrication system 168 ) may use a hydrocarbon fluid (eg, oil) for lubrication, where the oil circulates through the inner surfaces of the oil purge lines.

[0081] The engine 100 discussed herein is provided as an example only. In other embodiments, any other suitable engine may be used with aspects of the present disclosure. For example, in other embodiments, the engine may be any other suitable gas turbine engine, such as a turboshaft engine, a turboprop engine, a turbojet engine, an unducted single fan engine, etc. In this manner, in other embodiments, the gas turbine engine may have other suitable configurations, such as a direct drive configuration, a fixed pitch fan, or other suitable number or arrangement of shafts, compressors, turbines, fans, etc. Additionally, while Figure 2 A particular engine 100 is depicted in the drawings, but the catalytic coatings disclosed herein may be used more generally and / or with other engine embodiments. For example, in alternative embodiments, aspects of the present disclosure may be incorporated into or otherwise used with any other type of engine, such as a reciprocating engine. Additionally, in other exemplary embodiments, the exemplary engine 100 may include or be operably connected to any other suitable accessory system. Additionally or alternatively, the exemplary engine 100 may not include or may not be operably connected to one or more of the accessory systems 162, 164, 166, and 168 discussed above.

[0082] Figure 3 The combustion section 114 ( Figure 2 ) burner 300. Figure 3 Yes Display Figure 2 Detailed view of detail 3 in FIG. The combustor 300 is an annular combustor that includes a combustion chamber 302 defined between an inner liner 304 and an outer liner 306. Each of the inner liner 304 and the outer liner 306 is oriented about the longitudinal centerline axis 101 ( Figure 2 ) is annular. The combustor 300 also includes a combustor casing 308, which is also annular about the longitudinal centerline axis 101 of the engine 100. The combustor casing 308 extends circumferentially around the inner liner 304 and the outer liner 306, which are located radially inward of the combustor casing 308. The combustor 300 also includes a dome 310 mounted to the forward end of each of the inner liner 304 and the outer liner 306. The dome 310 defines the upstream (or forward) end of the combustion chamber 302.

[0083] Multiple mixer assemblies 210 ( Figure 3 The plurality of mixer assemblies 210 are spaced circumferentially around the longitudinal centerline axis 101 of the engine 100. Figure 3In the illustrated embodiment, each mixer assembly 210 is a twin annular premixing swirler (TAPS) that includes a main mixer 212 and a pilot mixer (not shown). For example, the pilot mixer is supplied with fuel by the fuel injector 200 during the entire engine operating cycle, while the main mixer 212 is supplied with fuel by the fuel injector 200 only during periods of increased power regulation in the engine operating cycle (e.g., during takeoff and climb). The TAPS mixer assembly 210 is provided by way of example, and the catalytic coatings discussed herein can be applied to other mixer assembly designs and other combustor designs.

[0084] As described above, the HP compressor 112 ( Figure 2 ) of the compressor section of the HP compressor 112, and the combustor 300 receives an annular flow of this pressurized air from the discharge outlet (compressor discharge outlet 216) of the HP compressor 112. This air may be referred to as compressor discharge pressure air. A portion of the compressor discharge air flows into the mixer assembly 210. Fuel is injected into the air in the mixer assembly 210 to mix with the air and form a fuel-air mixture. The fuel-air mixture is provided from the mixer assembly 210 to the combustion chamber 302 for combustion. Ignition of the fuel-air mixture is accomplished by the igniter 312, and the resulting combustion gases flow in an axial direction toward and into the annular first stage turbine nozzle 314. The first stage turbine nozzle 314 is defined by an annular flow passage that includes a plurality of radially extending, circularly spaced nozzle vanes 316 that deflect the gas so that the gas flows at an angle and impinges on the HP turbine 116 ( Figure 2 ) of the first stage turbine blades (not shown) of the first turbine (not shown).

[0085] The fuel injector 200 is secured to the combustor casing 308 via a nozzle mount. In this embodiment, the nozzle mount is a flange 202 integrally formed with the stem 204 of the fuel injector 200. The flange 202 is secured to the combustor casing 308 and sealed thereto. The stem 204 includes a flow passage through which hydrocarbon fuel flows and extends radially inward from the flange 202. The fuel injector 200 also includes a fuel nozzle tip 220, which is part of the mixer assembly 210, through which fuel is injected into the combustion chamber 302.

[0086] Figure 4 Shows Figure 3 The mixer assembly 210 of the combustor 300 is shown in FIG. Figure 4 Yes Display Figure 3 Detailed view of detail 5, and with Figure 3 is a cross-sectional view Figure 1 Sample, Figure 4Also a cross-sectional view of the mixer assembly 210. The fuel nozzle tip 220 ( Figure 3 ) includes a fuel nozzle body 222 and a rear heat shield 224 attached to the fuel nozzle body 222. The fuel nozzle body 222 may be mounted to, for example, an inlet cowling. The inlet cowling is connected to or integral with the stem 204 ( Figure 3 ). The fuel nozzle body 222 may include, for example, a main fuel nozzle and a dual-hole pilot fuel injector tip having a primary pilot fuel hole and a secondary pilot fuel hole. The primary pilot fuel hole and the secondary pilot fuel hole may be substantially concentric with each other and substantially centered on an annular pilot inlet 246. The main fuel nozzle surrounds the pilot inlet 246, and the pilot inlet 246 is located between the main fuel nozzle and the dual-hole pilot fuel injector tip. In this embodiment, the fuel nozzle tip 220 (see Figure 3 ) is circular about an axis extending through the center of the primary pilot fuel hole. In the following discussion, various features of the fuel nozzle tip 220 may be discussed relative to this axis. Fuel is supplied to the primary fuel nozzle via rod 204. The primary fuel nozzle can inject fuel in a radially outward direction through a circular array of primary fuel injection holes formed on the outer surface of the fuel nozzle body 222. Fuel is also supplied to the primary pilot fuel hole and the secondary pilot fuel hole via rod 204. The pilot mixer is supported by an annular pilot housing 270.

[0087] Pilot housing 270 includes a tapered wall section 272 that surrounds a tapered pilot mixing chamber 274, which is in fluid communication with the pilot mixer and downstream of the pilot mixer, more specifically, the outlet. Pilot mixing chamber 274 is also fluidly connected to the primary and secondary pilot fuel orifices and downstream of the primary and secondary pilot fuel orifices. Pilot mixing chamber 274 is a passageway for fuel injector 200, and more specifically, for fuel nozzle tip 220. Since fuel nozzle tip 220 is also part of mixer assembly 210, pilot mixing chamber 274 is also a passageway for mixer assembly 210.

[0088] Thus, the conical wall section 272 of the pilot housing 270 is a channel wall that includes a channel wall surface 276 facing the pilot mixing chamber 274 (channel). In this embodiment, the conical wall section 272 is part of a second venturi 280 formed by the pilot housing 270. The second venturi 280 includes a converging section 282, a diverging section 284, and a throat 286 between the converging section 282 and the diverging section 284. The diverging section 284 is provided by the conical wall section 272, extends downstream from the throat 286, and is continuous with the exposed surface 228 of the aft heat shield 224. The exposed surface 228 in this embodiment forms a conical wall section of the aft heat shield 224 that is coplanar with the wall surface 276 of the conical wall section 272. The diverging section 284 has an upstream end, which in this embodiment is a throat 286, and a downstream end, which in this embodiment is the outlet 278 of the pilot mixing chamber 274. Figure 4 As shown, the cross-sectional area of ​​the second venturi tube 280 at the outlet 278 (downstream end) is greater than the cross-sectional area of ​​the second venturi tube 280 at the throat 286 (upstream end).

[0089] Air flows through the outer pilot swirler, through the converging section 282, and toward the throat 286. This air mixes with the fuel-air mixture from the outlet and moves through the throat 286 to the diverging section 284 and the aft heat shield 224. As the fuel-air mixture flows through the pilot mixing chamber 274, through the pilot mixing chamber 274 outlet 278, and into the combustion chamber 302, the pilot mixing chamber 274, and more specifically, the wall surface 276 of the tapered wall section 272, is exposed to the hydrocarbon fuel. Due to their proximity to the combustion chamber 302 and the primary combustion zone, the fuel, tapered wall section 272, and aft heat shield 224 are exposed to high temperatures. For example, the tapered wall section 272 and aft heat shield 224 may be exposed to temperatures ranging from 300°C to 600°C and from 600°C to 1400°C, respectively.

[0090] The pilot housing 270 and the rear heat shield 224 are made of materials suitable for these high-temperature environments, including, for example, stainless steel, corrosion-resistant alloys of nickel and chromium, and high-strength nickel-based alloys. Therefore, the pilot housing 270 and the rear heat shield 224 may be formed of a metal alloy selected from the group consisting of iron-based alloys, nickel-based alloys, cobalt-based alloys, and chromium-based alloys. Consequently, the exposed surfaces of these materials at these temperatures (more specifically, the wall surfaces 276) may be susceptible to significant accumulation of coke and / or partially burned fuel deposits. The coke formed on such materials may be strongly bonded to these metal components of the fuel nozzle tip 220, resulting in the formation of a thick coke layer with large particles. As described above, coke can accumulate to considerable thickness on these surfaces, and large pieces of coke may break off and become internal objects, which can cause significant damage to components downstream of the fuel nozzle (hot gas path components).

[0091] To prevent coke accumulation and the above-mentioned problems, at least a portion of the surface of the second venturi tube 280 (including, for example, the wall surface 276) and the rear heat shield 224 may be coated with a catalytic coating 288 to inhibit coke deposition and accumulation. As described above, the pilot mixing chamber 274 is a channel, and in the embodiments discussed herein, a portion of the channel wall is a coated channel wall coated with a catalytic coating 288. The coated channel wall is located downstream of the fuel injection port (primary pilot fuel hole and secondary pilot fuel hole in this embodiment). As described above, air flows through the pilot mixing chamber 274 (channel) and is introduced by the air inlet. In these embodiments, the air inlet is located upstream of the coated channel wall. More specifically, air is introduced into the pilot mixing chamber 274 (channel) by the pilot inlet 246 through the inner pilot swirler and the outer pilot swirler. The air flowing through the inner pilot swirler is also introduced into the pilot mixing chamber 274 via the outlet 278.

[0092] The exposed surface of the underlying (base) material of the pilot shell 270, more specifically, the tapered wall section 272 or the rear heat shield 224, promotes the formation of thick, large-particle coke, and the catalytic coating 288 in this embodiment is applied as a continuous layer on the wall surface 276 to avoid discontinuities that would expose the base material. Depending on the application area, the thickness of the catalytic coating 288 can be appropriately determined to take into account, for example, the coke accumulation rate, the catalyst wear rate, etc. For example, the thickness of the catalytic coating 288 can be less than 200 μm, such as less than 100 μm, less than 10 μm, less than 5 μm, or less than 2 μm. In some embodiments, the thickness of the catalytic coating 288 can be from 1 μm to 200 μm. In other embodiments, the thickness of the catalytic coating 288 can be, for example, less than 300 nm, such as less than 100 nm. In some embodiments, the thickness of the catalytic coating 288 can be from 20 nm to 300 nm. In some embodiments, the thickness of the catalytic coating 288 can be from 300 nm to 10 μm. Typically, thicknesses can range from 0.5 mils to 4 mils. Higher thicknesses can be helpful if the layer is subject to constant erosion / corrosion during operation. However, thicker layers may lead to more instability issues related to coating delamination / flaking due to cyclic thermal stresses. The thickness should be selected to ensure that the coating remains in place for as long as possible, prevent flaking, and account for losses caused by erosion / corrosion.

[0093] The catalytic coating 288 can have a smooth surface finish with a surface roughness Ra between 0.01 μm and 0.4 μm. The smooth surface finish can also help prevent coke from adhering to the second venturi tube 280. In some embodiments, when deposited using, for example, air plasma spray, the catalytic coating 288 can have a surface finish with a surface roughness Ra of 5 μm to 10 μm; in other embodiments, when deposited using, for example, electron beam physical vapor deposition, the catalytic coating 288 can have a surface finish with a surface roughness Ra of 0.5 μm to 1.5 μm. Other techniques for catalytic coating deposition can include slurry spraying, suspension plasma spraying, and solution precursor plasma spraying, all of which can have a surface finish with a surface roughness Ra of 0.5 μm to 10 μm.

[0094] In the preceding discussion, the combustor 300 and mixer assembly 210 are configured to use a twin annular premixing swirler (TAPS), but the catalytic coating 288 discussed herein may be applied to other mixer assembly designs and other combustor designs. Figure 5 Another example of a combustor 400 is shown.

[0095] Figure 5 is a cross-sectional view of the combustor 400 showing a rich-burn combustor design. Figure 6 Shows Figure 5 Mixer assembly 410 of combustor 400 is shown in FIG. Figure 6 Yes Display Figure 5 Detailed view of detail 6, and Figure 5 is a cross-sectional view Figure 1 Sample, Figure 6 It is also a cross-sectional view of the mixer assembly 410. The burner 400 and the mixer assembly 410 in this embodiment include the same or similar components as the burner 300 and the mixer assembly 210 discussed above. Components in this embodiment that are the same or similar to the above-mentioned components are identified with the same reference numerals, and detailed descriptions of these components are omitted.

[0096] The combustor 400 in this embodiment illustrates a rich-burn combustor. Multiple mixer assemblies 410 (only one shown) are spaced around the dome 310. Fuel is injected into the mixer assemblies 410 through fuel injection ports 402. Fuel injection ports 402 inject fuel in a generally downstream direction and into compressed air flowing through a first swirler (not shown). The fuel is injected into a mixing chamber 404, which mixes the fuel with the compressed air to form a fuel-air mixture. Like the pilot mixing chamber 274 discussed above, the mixing chamber 404 in this embodiment is a passageway of the fuel injector 200 having a wall section 406 including a passageway wall surface 408 facing the mixing chamber 404 (the passageway). In this embodiment, the wall section 406 is a portion of a venturi 420, which includes a converging section 422, a diverging section 424, and a throat 426 between the converging and diverging sections 422 and 424. In the present embodiment, a catalytic coating 288 is formed on the surface of the venturi tube 420. The fuel-air mixture flows out through the outlet 428 of the mixing chamber 404 and is combined with air flowing through a second swirler (not shown) located upstream of the exposed surface 228 of the aft heat shield 224. In the present embodiment, a catalytic coating 288 is also formed on the exposed surface 228 of the aft heat shield 224.

[0097] As described above, the catalytic coating 288 can be applied to a venturi component (e.g., venturi 280 or venturi 420). For example, the catalytic coating 288 can be applied directly to the surface of the venturi wall 502, such as Figure 7 Additionally or alternatively, a catalytic coating 288 may be applied to the surface of the TBC 506 present on the surface of the AHS 510. The above description of such components also applies here.

[0098] The above discussion is merely exemplary, and the catalytic coating may be applied to any substrate, such as a metal substrate, a ceramic substrate, a metal substrate coated with a ceramic layer, or a ceramic substrate coated with a metal layer.

[0099] Figure 8A A catalytic coating 288 is depicted on a universal substrate 600. Universal substrate 600 can be a metal substrate, a ceramic substrate, a metal substrate coated with a ceramic layer, or a ceramic substrate coated with a metal layer. Universal substrate 600 can be part of a component 602 (e.g., a component positioned or otherwise arranged to come into contact with, for example, a hydrocarbon fluid (e.g., fuel, oil, etc.), as described above), and catalytic coating 288 can be applied to a hydrocarbon fluid-facing surface of the substrate (e.g., a surface facing or otherwise defining a channel 604) for the hydrocarbon fluid to flow therethrough.

[0100] Figure 8BAlso depicted is a catalytic coating 288 on the common substrate 600 . Figure 8B The component 606 depicted in FIG. Figure 8A 6. In some applications, the common substrate 600 may be metal and may have a ceramic coating 608 (e.g., a thermal barrier coating (TBC)) on the metal substrate. As discussed further herein, the catalytic coating 288 may be applied as a coating on top of the TBC (e.g., Figure 8A (as shown) can also be integrated into the TBC. Exemplary materials for TBCs include: yttria-stabilized zirconia (YSZ, such as 8YSZ, 20YSZ, 55YSZ), lanthanum (La)-gadolinium (Gd)-zirconate, lanthanum (La)-ytterbium (Yb)-zirconate, lanthanum (La)-gadolinium (Gd)-ytterbium (Yb)-zirconate, rare earth-tantalum (Ta)-zirconate, rare earth-niobium (Nb)-zirconate, and (ZrO2) (1-q) (Y2O3) q (wherein q ranges from 0.04 to 0.5.) The metal substrate may include, for example, iron-based alloys, nickel-based alloys, cobalt-based alloys, alloys containing cobalt and chromium, alloys containing platinum and aluminum, alloys containing nickel and aluminum, or alloys containing nickel, chromium, aluminum, and yttrium.

[0101] The inventors have unexpectedly discovered that by controlling the structure of the catalytic coating, the durability of the catalytic coating can be improved. For example, the inventors have discovered that a catalytic coating (comprising a first layer, a second layer, and a third layer, wherein the volume percent porosity of the second layer is greater than the volume percent porosity of each of the first layer and the third layer) unexpectedly exhibits enhanced durability compared to a similar coating without such a structure. For example, as discussed in the working examples below, the inventors discovered that a coated component (having a three-layer structure) lost more than 7 wt% of its mass after being exposed to a jet of hot air at a temperature of 1100 degrees Fahrenheit and a rate of 104 L / min for one hour, while a coated component (having a three-layer structure) lost less than 2 wt% of its mass after being subjected to the same testing conditions.

[0102] Figure 9 A cross-sectional view of a component 602 having a catalytic coating 288 on a substrate 600 is depicted. The catalytic coating 288 has multiple layers, including a first layer 700, a second layer 702, and a third layer 704. Figure 9 As shown, the second layer 702 may be an intermediate layer located between the first layer 700 and the third layer 704. The third layer 704 is a surface layer of the catalytic coating 288 that defines the channels 604 and is directly exposed to the fluid flowing therethrough. The first layer 700 is the bottom layer adjacent to the substrate 600 and is Figure 9In the illustrated catalytic coating 288, the first layer 700 is directly adjacent to the substrate 600 and can be used to bond or otherwise attach the catalytic coating 288 to the substrate 600. Figure 9 As shown, the first layer is in contact with the substrate, the second layer is in contact with the first layer, and the third layer is in contact with the second layer.

[0103] Each of the plurality of layers (i.e., first layer 700, second layer 702, and third layer 704) includes a ceramic material and a precious metal. More specifically, first layer 700 includes a first ceramic material and a first precious metal, second layer 702 includes a second ceramic material and a second precious metal, and third layer 704 includes a third ceramic material and a third precious metal.

[0104] The first layer 700 includes a plurality of particles 710 and a volume percent porosity (e.g., in a range of 10% to 30%). In some embodiments, the average diameter of the plurality of particles 710 of the first layer 700 ranges from 0.5 μm to 1 μm. For example, the average diameter can be selected, for example, to achieve a desired microstructure to improve catalytic performance (e.g., by increasing surface area) or durability (adhesion, cohesion, and compliance), or both. In the first layer 700, the average diameter can be selected, for example, to achieve good adhesion and cohesion (by, for example, increasing contact points with the substrate). Similarly, the third layer 704 has a plurality of particles 716 and a volume percent porosity (e.g., in a range of 5% to 30%). In some embodiments, the average diameter of the plurality of particles 716 of the third layer 704 ranges from 0.5 μm to 2 μm. In third layer 704, the average diameter can be selected to achieve good catalytic performance and enhance inter-particle cohesion to achieve durability against shear forces from flowing media. Second layer 702 also comprises a plurality of particles, but the particle sizes of the plurality of particles in second layer 702 are multimodal (e.g., bimodal) distributions, wherein a plurality of first particles 712 have a first mode diameter, and a plurality of second particles 714 have a second mode diameter. The second mode diameter is greater than the first mode diameter. The second mode diameter can be greater than the average diameter of the particles in first layer 700, greater than the average diameter of the particles in third layer 704, or greater than both. The first mode diameter can range from 0.5 μm to 2 μm, and the second mode diameter can range from 4 μm to 20 μm. Thus, the second mode diameter can be at least 2 μm greater than the first mode diameter, for example, at least 2 μm greater than the first mode diameter and greater than 100 μm greater than the first mode diameter. In second layer 702, the first mode diameter and the second mode diameter can be selected to achieve good conformability and durability to the layer. The volume percent porosity of the second layer 702 can range from 20% to 60%. The volume percent porosity of the second layer 702 can be greater than the volume percent porosity of the first layer and / or the volume percent porosity of the third layer. When the catalytic coating 288 is structured as described herein, the durability of the catalytic coating 288 is unexpectedly improved compared to a coating lacking such a structure.

[0105] Depending on the application, the thickness of the catalytic coating can be appropriately determined to take into account, for example, the coke accumulation rate, the catalytic coating wear rate, etc. For example, the thickness of the catalytic coating can range from 25 μm to 80 μm, from 30 μm to 75 μm, from 40 μm to 70 μm, or from 50 μm to 60 μm. In certain embodiments, a thin coating with good durability and long-lasting performance can be used.

[0106] Likewise, the thickness of each layer can be controlled to adjust the durability and / or catalytic performance of the catalytic coating. For example, the thickness of the first layer can range from 2.5 μm to 15 μm, the thickness of the second layer can range from 25 μm to 51 μm, and the thickness of the third layer can range from 2.5 μm to 15 μm.

[0107] The catalytic coating may also contain a binder (such as silica) to improve the cohesion of the coating.

[0108] The catalytic coating can be applied to the substrate using various techniques. For example, the catalytic coating can be applied to the substrate by spraying particles of a first ceramic material and a first precious metal onto the substrate, such that the particles of the first ceramic material and the first precious metal have an average particle size ranging from 0.5 μm to 1 μm; spraying particles of a second ceramic material and a second precious metal, such that the particles of the second ceramic material and the second precious metal have a first plurality of particles having an average particle size ranging from 0.5 μm to 2 μm and a second plurality of particles having an average particle size ranging from 4 μm to 20 μm; spraying particles of a third ceramic material and a third precious metal, such that the particles of the third ceramic material and the third precious metal have an average particle size ranging from 0.5 μm to 2 μm; and sintering the particles to form a coated component.

[0109] The sintering step can be performed at various temperatures and for various durations. For example, the sintering step can be performed at a temperature in the range of 1500 degrees Fahrenheit to 2000 degrees Fahrenheit. The sintering step can be performed for a duration in the range of 10 minutes to 5 hours (e.g., 30 minutes to 90 minutes). In certain embodiments, the catalytic coating is flashed. For example, in certain embodiments, the catalytic coating is flashed by heating one side of the coating and cooling the other side of the coating. In certain embodiments, the catalytic coating is flashed by heating one side of the coating for 1 to 10 heating cycles.

[0110] Without wishing to be bound by theory, it is believed that during the sintering step, particles of a first ceramic material and a first precious metal are melted to form a plurality of particles having an average diameter in the range of 0.5 μm to 1 μm in the first layer of the catalytic coating, during the sintering step, particles of a second ceramic material and a second precious metal are melted to form a plurality of particles having a bimodal distribution in the second layer of the catalytic coating (wherein the first mode diameter is in the range of 0.5 μm to 2 μm and the second mode diameter is in the range of 4 μm to 20 μm), and during the sintering step, particles of a third ceramic material and a third precious metal are melted to form a plurality of particles having an average diameter in the range of 0.5 μm to 2 μm in the third layer of the catalytic coating. In certain embodiments, the sintering step includes heating the coating starting from the top layer so that the top layer reaches a higher temperature in the range of 1500 degrees Fahrenheit to 2000 degrees Fahrenheit. The top layer can be sufficiently sintered to result in the formation of sintered necks between the particles, thereby improving the durability of the coating against shear forces generated by the flowing fluid medium and providing mechanical durability without sacrificing interconnected open porosity.

[0111] It has been surprisingly discovered that the average particle size in each of the first layer 700, the second layer 702, and the third layer 704 affects the durability of the coating. The average particle size in each of the first layer, the second layer, and the third layer can be independently controlled by, for example, adjusting the particle size of the ceramic material and / or the precious metal used to form the respective layer. Additionally and / or alternatively, the average particle size in each of the first layer, the second layer, and the third layer can be independently controlled by, for example, adjusting the chemical composition and / or heat treatment conditions used to form the respective layer. In certain embodiments, the first layer has a plurality of particles having an average diameter ranging from 0.5 μm to 1 μm. In certain embodiments, the second layer has a plurality of particles having a bimodal distribution, wherein the first mode diameter ranges from 0.5 μm to 2 μm and the second mode diameter ranges from 4 μm to 20 μm. In certain embodiments, the third layer has a plurality of particles having an average diameter ranging from 0.5 μm to 2 μm.

[0112] Surprisingly, it was found that the volume percent porosity in each of the first layer 700, the second layer 702, and the third layer 704 affects the durability of the coating. Without wishing to be bound by theory, it is believed that the volume percent porosity affects the strain tolerance of the coating when the coating is subjected to mechanical and / or thermally induced strain. In certain embodiments, the volume percent porosity of the first layer ranges from 10% to 30%. In certain embodiments, the volume percent porosity of the second layer ranges from 20% to 60%. In certain embodiments, the volume percent porosity of the third layer ranges from 5% to 30%. In certain embodiments, the coating has open surface pores connected to the layers below. The open pores at the top layer allow reactants (such as air and coke) to enter more catalytic sites below the top layer, thereby improving the coke oxidation kinetics. The pores of each layer can be interconnected, allowing reactants (such as air and coke) to enter more catalytic sites.

[0113] Regardless of the chemical composition of the first ceramic material, the first noble metal, the second ceramic material, the second noble metal, the third ceramic material, and the third noble metal, the structure of the coating is believed to provide enhanced coating durability. In certain embodiments, the first ceramic material, the second ceramic material, and the third ceramic material each have a different chemical composition. In certain embodiments, the first ceramic material, the second ceramic material, and the third ceramic material each have the same chemical composition. In certain embodiments, the first noble metal, the second noble metal, and the third noble metal are each independently selected from rhenium, ruthenium, rhodium, palladium, silver, osmium, iridium, platinum, and gold. For example, in certain embodiments, the first inert metal, the second inert metal, and the third inert metal are each different inert metals. As other examples, in certain embodiments, the first inert metal, the second inert metal, and the third inert metal are the same inert metal.

[0114] In certain embodiments, the first ceramic material, the second ceramic material, and the third ceramic material are each independently selected from the group consisting of: x E y L z MO u A metal oxide, wherein A is one or more alkaline earth elements selected from magnesium, calcium, strontium and barium; x is in the range of 0 to 1; E is one or more alkali metals selected from lithium, sodium and potassium; y is in the range of 0 to 1; L is one or more lanthanoid elements selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, ytterbium and lutetium; z is in the range of 0 to 1; M is one or more elements selected from titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, tantalum, tungsten, rhenium, iridium, platinum, gold and bismuth; O is oxygen; and u is in the range of 0.95 to 6.

[0115] For the reaction of catalytic degradation of coke, different metal oxides of formula (I) can have different reactivity and / or selectivity. In certain embodiments, u ranges from 0.95 to 3. In certain embodiments, A is barium or strontium. In certain embodiments, E is lithium, sodium or potassium. In certain embodiments, L is lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium or ytterbium. In some embodiments, M is scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, tungsten, aluminum, gallium, indium, thallium, tin, lead, silicon or germanium. In certain embodiments, the metal oxide is selected from the group consisting of Co3O4, Ni x Co 3-x O4, Fe x Co 3-x O4, Cu x Co 3-x O4, Cr x Co 3- x O4, Pr6O 11 , LiMn2O4, Al2O3, PbO, Pb 1-x Sr x CoO3, Pb 1-x Ba x CoO3, SrCoO u , BaCoO u , Ln x A 1-x CoO u , Sr 0.8 Pr 0.2 CoO3, Ba 0.8 Ce 0.2 CoO3, Ba 0.8 Pr 0.2 CoO3, Ln x Ca y Sr z Ba [1-(x+y+z)] CoO3, Ln x Li y Sr z Ba [1-(x+y+z)] CoO3, smithsonite, manganite, chromite, ferrite perovskite, xMoO3-yCo3O4-zLi2O, M x E y Co 3-(x+y) O u , M x E y A z Co 3-(x+y+z) O u, Mn2O3, Mn3O4, Mn2O7, manganese-doped TiO2, Fe2O3, Fe3O4, ZnFe2O4, Bi x Sn 1-x O u ,In x Sn y O z , one or more components among Bi2O3-Co3O4 and CeO2.

[0116] As described above, the catalytic coating can effectively reduce coke and can be used in various methods, such as for oxidizing coke. In certain embodiments, the method of oxidizing coke includes contacting the coke with the catalytic coating at a temperature in the range of 300 degrees Fahrenheit to 1100 degrees Fahrenheit, such that the coke is selectively oxidized by the catalytic coating in the presence of a carbon oxide fuel.

[0117] Example

[0118] The specific embodiments will be described with reference to the following examples. These examples are disclosed only in order to illustrate the present disclosure and should not limit the scope of the present disclosure in any way.

[0119] Example 1: The catalytic coating was prepared according to the following steps.

[0120] Use fine particles with relatively high solids content (50% to 70%) 50 The first layer (bottom) was deposited on a metal substrate (Inconel / NiAl) by slurry spraying. An organic solvent (butanol / ethanol) was used to prepare a slurry containing 1 to 5 wt% of a silica-based binder. During the coating process, the thickness of the coating was controlled by the number of sprays of the sprayer and was kept in the range of 0.1 to 0.5 mils. The same method was used, but by using a bimodal particle size distribution (d 50 Between 0.5 and 2 μm and between 4 and 20 μm), the second layer (middle) was deposited. The volume fraction of finer particles was varied between 10% and 50% to achieve the desired microstructure. Using finer particles (d 50 The third layer (top) is sprayed with a thickness of 0.5 to 2 μm. A short time interval (1 to 3 minutes) is given between the two different layers to dry the coating at room temperature. The entire coating is dried at room temperature for two hours and then cured at 900 degrees Fahrenheit for two hours. Finally, the coating substrate is sintered from the top by a flash firing technique to densify the system while maintaining interconnected porosity. During the flash firing process, the temperature of the top layer is maintained between 1500 degrees Fahrenheit and 2000 degrees Fahrenheit, depending on the metal substrate.

[0121] The samples were mounted in epoxy resin and cross-sectioned to examine the microstructure and the interface between the coating and the substrate under a scanning electron microscope (SEM). The ceramic material and precious metal in each layer were 90% ceria and 10% silver, and the substrate was a platinum-coated nickel alloy.

[0122] Example 2: Air impact test.

[0123] The sample was mounted on a stand and placed in the furnace perpendicular to the hot air nozzle path. The test was conducted at 1100 degrees Fahrenheit for one hour. The hot air velocity was maintained at 104 L / min. The sample weight was measured and optical images were taken before and after the experiment.

[0124] Figure 10A A control sample after air impact testing is depicted, showing ablated region 1001. The control sample, made of particles of 90% ceria and 10% silver, lacks the three-layer coating structure. During the air impact test, this sample experienced a mass loss of 7.3%.

[0125] Figure 10B A sample after air impact testing is depicted, showing ablated region 1002. The sample is made of particles of 90% ceria and 10% silver, has a three-layer coating structure, and is flash-cured at 1700 degrees Fahrenheit. During the air impact test, the sample experienced a mass loss of 1.5%.

[0126] Example 3: Thermal cycle test.

[0127] Oven cycling tests were conducted in a bottom-loading thermal cycling oven (CM Furnaces Inc.). A 30-minute cycle consisted of a 5-minute heating period to the cycling temperature, followed by a 20-minute dwell at a maximum temperature of 1100°F. The final step was a 5-minute forced air cool-down to room temperature. A total of 100 cycles were performed to evaluate the coating's durability.

[0128] As described above, the three-layer structure unexpectedly improves the durability of the catalytic coating compared to a coating having the same composition but a different structure that has not been flashed.

[0129] Other aspects of the disclosure are provided by the subject matter of the following clauses.

[0130] A catalytic coating comprises: a first layer having a first ceramic material and a first precious metal, wherein the first layer has a volume percent porosity; a second layer having a second ceramic material and a second precious metal, wherein the second layer has a plurality of particles having a multimodal particle size distribution and the volume percent porosity of the second layer is greater than the volume percent porosity of the first layer; and a third layer having a third ceramic material and a third precious metal, wherein the volume percent porosity of the third layer is less than the volume percent porosity of the second layer.

[0131] A catalytic coating according to the preceding clause, wherein the first layer has a plurality of particles having an average diameter in the range of 0.5 μm to 1 μm, and the volume percentage porosity of the first layer is in the range of 10% to 30%; the second layer has a bimodal particle size distribution, wherein the first mode diameter is in the range of 0.5 μm to 2 μm, the second mode diameter is in the range of 4 μm to 20 μm, and the volume percentage porosity of the second layer is in the range of 20% to 60%; the third layer has a plurality of particles having an average diameter in the range of 0.5 μm to 2 μm, and the volume percentage porosity of the third layer is in the range of 5% to 30%.

[0132] A catalytic coating according to any of the preceding clauses, wherein the first ceramic material, the second ceramic material and the third ceramic material have the same chemical composition.

[0133] A catalytic coating according to any of the preceding clauses, wherein the thickness of the first layer is in the range of 2.5 μm to 15 μm.

[0134] A catalytic coating according to any of the preceding clauses, wherein the thickness of the second layer is in the range of 25 μm to 50 μm.

[0135] A catalytic coating according to any of the preceding clauses, wherein the thickness of the third layer is in the range of 2.5 μm to 15 μm.

[0136] A catalytic coating according to any of the preceding clauses, wherein each layer comprises a binder.

[0137] A catalytic coating according to any of the preceding clauses, wherein each layer comprises a binder comprising silica.

[0138] A coated component comprising the catalytic coating according to any one of the preceding clauses coated on a substrate.

[0139] The coated component of the preceding clause, wherein the coated component loses less than 7 wt% of the coating mass when exposed to a hot air jet having a temperature of 1100 degrees Fahrenheit and a velocity of 104 L / min for one hour.

[0140] A coated component according to any of the preceding clauses, wherein the first layer is in contact with the substrate, the second layer is in contact with the first layer, and the third layer is in contact with the second layer.

[0141] A coated component according to any of the preceding clauses, wherein the coated component is an aircraft component.

[0142] A coated component according to any of the preceding clauses, wherein the coated component is a gas turbine engine component.

[0143] A coated component according to any of the preceding clauses, wherein the coated component is a venturi surface, a fuel nozzle, a fuel circuit component or an oil lubrication circuit component.

[0144] The coated component according to any of the preceding clauses, wherein the substrate is a metal substrate, a ceramic substrate, a metal substrate coated with a ceramic layer, or a ceramic substrate coated with a metal layer.

[0145] The coated component according to any of the preceding clauses, wherein the substrate is a metal substrate selected from iron-based alloys, nickel-based alloys, cobalt-based alloys, alloys containing cobalt and chromium, alloys containing platinum and aluminum, alloys containing nickel and aluminum, and alloys containing nickel, chromium, aluminum and yttrium.

[0146] A coated component according to any of the preceding clauses, wherein the substrate is a metal substrate coated with a ceramic layer, the ceramic layer being a thermal barrier coating.

[0147] A method of oxidizing coke, the method comprising contacting the coke with a catalytic coating as described in any of the preceding clauses at a temperature in the range of 300 degrees Fahrenheit to 1100 degrees Fahrenheit.

[0148] A method of making a coated component as described in any of the preceding clauses, the method comprising: spraying particles of a first ceramic material and a first precious metal on a substrate, wherein the particles of the first ceramic material and the first precious metal have an average particle size in the range of 0.5 μm to 1 μm; spraying particles of a second ceramic material and a second precious metal, wherein the particles of the second ceramic material and the second precious metal have a first plurality of particles having an average particle size in the range of 0.5 μm to 1 μm and a second plurality of particles having an average particle size in the range of 4 μm to 20 μm; spraying particles of a third ceramic material and a third precious metal, wherein the particles of the third ceramic material and the third precious metal have an average particle size in the range of 0.5 μm to 2 μm; and sintering at least some of the particles of the third ceramic material and the third precious metal at a temperature in the range of 1500 degrees Fahrenheit to 2000 degrees Fahrenheit.

[0149] A method according to the preceding clauses, wherein the sintering melts particles of a first ceramic material and a first precious metal to form a plurality of particles having an average diameter in the range of 0.5 μm to 1 μm in the first layer of the catalytic coating; the sintering melts particles of a second ceramic material and a second precious metal to form a plurality of particles having a bimodal distribution in the second layer of the catalytic coating, wherein the bimodal distribution has a first mode diameter in the range of 0.5 μm to 2 μm and a second mode diameter in the range of 4 μm to 20 μm; and the sintering melts particles of a third ceramic material and a third precious metal to form a plurality of particles having an average diameter in the range of 0.5 μm to 2 μm in the third layer of the catalytic coating.

[0150] A coated component includes a substrate and a catalytic coating, the catalytic coating having: a first layer in contact with the substrate, the first layer including a first ceramic material and a first precious metal, wherein the first layer has a volume percentage porosity; a second layer in contact with the first layer, the second layer including a second ceramic material and a second precious metal, wherein the second layer has a plurality of particles with a multi-peak particle size distribution, and the volume percentage porosity of the second layer is greater than the volume percentage porosity of the first layer; and a third layer in contact with the second layer, the third layer including a third ceramic material and a third precious metal, wherein the volume percentage porosity of the third layer is less than the volume percentage porosity of the second layer.

[0151] A coated component according to the preceding clause, wherein the first layer has a plurality of particles having an average diameter in the range of 0.5 μm to 1 μm, and the volume percent porosity of the first layer is in the range of 10% to 30%; the second layer has a bimodal particle size distribution, wherein the bimodal particle size distribution has a first mode diameter in the range of 0.5 μm to 2 μm and a second mode diameter in the range of 4 μm to 20 μm, and the volume percent porosity of the second layer is in the range of 20% to 60%; and the third layer has a plurality of particles having an average diameter in the range of 0.5 μm to 2 μm, and the volume percent porosity of the third layer is in the range of 5% to 30%.

[0152] The coated component according to any of the preceding clauses, wherein the first ceramic material, the second ceramic material and the third ceramic material have the same chemical composition.

[0153] A coated component according to any of the preceding clauses, wherein the first layer has a thickness in the range of 2.5 μm to 15 μm.

[0154] A coated component according to any of the preceding clauses, wherein the second layer has a thickness in the range of 25 μm to 50 μm.

[0155] A coated component according to any of the preceding clauses, wherein the third layer has a thickness in the range of 2.5 μm to 15 μm.

[0156] A coated component according to any of the preceding clauses, wherein each layer comprises a binder.

[0157] A coated component according to any of the preceding clauses, wherein each layer comprises a binder comprising silica.

[0158] A coated component according to any of the preceding clauses, wherein the coated component loses less than 7 wt% of the coating mass when exposed to a hot air jet having a temperature of 1100 degrees Fahrenheit and a velocity of 104 L / min for one hour.

[0159] The coated component according to any of the preceding clauses, wherein the first ceramic material, the second ceramic material and the third ceramic material are each independently selected from the group consisting of: x E y L z MO u A metal oxide, wherein A is one or more alkaline earth elements selected from magnesium, calcium, strontium and barium; x is in the range of 0 to 1; E is one or more alkali metals selected from lithium, sodium and potassium; y is in the range of 0 to 1; L is one or more lanthanoid elements selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, ytterbium and lutetium; z is in the range of 0 to 1; M is one or more elements selected from titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, tantalum, tungsten, rhenium, iridium, platinum, gold and bismuth; O is oxygen; and u is in the range of 0.95 to 6.

[0160] A coated component according to any of the preceding clauses, wherein the coated component is an aircraft component.

[0161] A coated component according to any of the preceding clauses, wherein the coated component is a gas turbine engine component.

[0162] A coated component according to any of the preceding clauses, wherein the coated component is a venturi surface, a fuel nozzle, a fuel circuit component or an oil lubrication circuit component.

[0163] The coated component according to any of the preceding clauses, wherein the substrate is a metal substrate, a ceramic substrate, a metal substrate coated with a ceramic layer, or a ceramic substrate coated with a metal layer.

[0164] The coated component according to any of the preceding clauses, wherein the substrate is a metal substrate selected from iron-based alloys, nickel-based alloys, cobalt-based alloys, alloys containing cobalt and chromium, alloys containing platinum and aluminum, alloys containing nickel and aluminum, and alloys containing nickel, chromium, aluminum and yttrium.

[0165] A coated component according to any of the preceding clauses, wherein the substrate is a metal substrate coated with a ceramic layer, the ceramic layer being a thermal barrier coating.

[0166] A method of oxidizing coke, the method comprising contacting the coke with a coated component as described in any of the preceding clauses at a temperature in the range of 300 degrees Fahrenheit to 1100 degrees Fahrenheit.

[0167] A method of making a coated component as described in any of the preceding clauses, the method comprising: spraying particles of a first ceramic material and a first precious metal on a substrate, wherein the particles of the first ceramic material and the first precious metal have an average particle size in the range of 0.5 μm to 1 μm; spraying particles of a second ceramic material and a second precious metal, wherein the particles of the second ceramic material and the second precious metal have a first plurality of particles having an average particle size in the range of 0.5 μm to 1 μm and a second plurality of particles having an average particle size in the range of 4 μm to 20 μm; spraying particles of a third ceramic material and a third precious metal, wherein the particles of the third ceramic material and the third precious metal have an average particle size in the range of 0.5 μm to 2 μm; and sintering at least some of the particles of the third ceramic material and the third precious metal at a temperature in the range of 1500 degrees Fahrenheit to 2000 degrees Fahrenheit.

[0168] A method according to the preceding clauses, wherein the sintering melts particles of a first ceramic material and a first precious metal to form a plurality of particles having an average diameter in the range of 0.5 μm to 1 μm in the first layer of the catalytic coating; the sintering melts particles of a second ceramic material and a second precious metal to form a plurality of particles having a bimodal distribution in the second layer of the catalytic coating, wherein the bimodal distribution has a first mode diameter in the range of 0.5 μm to 2 μm and a second mode diameter in the range of 4 μm to 20 μm; and the sintering melts particles of a third ceramic material and a third precious metal to form a plurality of particles having an average diameter in the range of 0.5 μm to 2 μm in the third layer of the catalytic coating.

[0169] A method according to any of the preceding clauses, wherein sintering comprises applying heat to the catalytic coating and cooling the substrate on a side opposite the catalytic coating.

[0170] An embodiment according to any of the preceding clauses, wherein the first ceramic material, the second ceramic material and the third ceramic material are each independently selected from formula (1) A x E y L z MO u A metal oxide, wherein A is one or more alkaline earth elements selected from magnesium, calcium, strontium and barium; x is in the range of 0 to 1; E is one or more alkali metals selected from lithium, sodium and potassium; y is in the range of 0 to 1; L is one or more lanthanoid elements selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, ytterbium and lutetium; z is in the range of 0 to 1; M is one or more elements selected from titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, tantalum, tungsten, rhenium, iridium, platinum, gold and bismuth; O is oxygen; and u is in the range of 0.95 to 6.

[0171] An embodiment as defined in the preceding clause, wherein u is in the range of 0.95 to 3.

[0172] An embodiment according to any of the preceding clauses, wherein A is barium or strontium.

[0173] An embodiment according to any of the preceding clauses, wherein E is lithium, sodium or potassium.

[0174] An embodiment according to any of the preceding clauses, wherein L is lanthanum, cerium, praseodymium, neodymium, samarium, gadolinium, or ytterbium.

[0175] An embodiment according to any of the preceding clauses, wherein M is scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, tungsten, aluminum, gallium, indium, thallium, tin, lead, silicon, or germanium.

[0176] According to any one of the preceding clauses, the first ceramic material, the second ceramic material and the third ceramic material are each independently selected from Co3O4, Ni x Co 3-x O4、Fe x Co 3-x O4、Cu x Co 3-x O4、Cr x Co 3-x O4、Pr6O 11 、LiMn2O4、Al2O3、PbO、Pb 1-x Sr x CoO3、Pb 1-x Ba x CoO3、SrCoO u 、BaCoO u 、Ln x A 1-x CoO u 、Sr 0.8 Pr 0.2 CoO3、Ba 0.8 Ce 0.2 CoO3、Ba 0.8 Pr 0.2 CoO3、Ln x Ca y Sr z Ba [1-(x+y+z)] CoO3、Ln x Li y Sr z Ba [1 - (x+y+z)] CoO3, arsenic cobaltite, manganite, ferrite perovskite, xMoO3-yCo3O4-zLi2O, M x Ey Co 3-(x+y) O u 、M x E y A z Co 3-(x+y+z) O u , Mn2O3, Mn3O4, Mn2O7, manganese-doped TiO2, Fe2O3, Fe3O4, ZnFe2O4, Bi x Sn 1-x O u 、In x Sn y O z , Bi2O3-Co3O4 and CeO2.

[0177] An embodiment according to any of the preceding clauses, wherein the catalytic coating is flashed.

[0178] An embodiment according to any of the preceding clauses, wherein the catalytic coating has been flashed by heating one side of the coating and cooling the other side of the coating.

[0179] An embodiment according to any of the preceding clauses, wherein the catalytic coating has been flashed by heating one side of the coating for 1 to 10 heating cycles.

[0180] An embodiment according to any of the preceding clauses, wherein the sintering step is a flash firing step.

[0181] An embodiment according to any of the preceding clauses, wherein the sintering step is a flash firing step, wherein one side of the coating is heated and the other side of the coating is cooled.

[0182] An embodiment according to any of the preceding clauses, wherein the sintering step is a flash firing step, wherein the catalytic coating is heated on one side of the coating for 1 to 10 heating cycles.

[0183] Although the foregoing description is directed to some exemplary embodiments of the present disclosure, other changes and modifications will be apparent to those skilled in the art and may be made without departing from the present disclosure. In addition, even if not explicitly stated above, the features described in conjunction with one embodiment of the present disclosure may also be used in conjunction with other embodiments.

Claims

1. A coated component for reducing coke in a gas turbine engine, the coated component comprising: substrate; as well as A catalytic coating, comprising: a first layer in contact with the substrate, the first layer comprising a first ceramic material and a first precious metal, wherein the first layer has a volume percent porosity; a second layer in contact with the first layer, the second layer comprising a second ceramic material and a second precious metal, wherein the second layer has a plurality of particles having a multimodal particle size distribution, and wherein the second layer has a volume percent porosity greater than the volume percent porosity of the first layer; and A third layer is in contact with the second layer, the third layer comprising a third ceramic material and a third precious metal, wherein a volume percent porosity of the third layer is less than a volume percent porosity of the second layer.

2. The coated component according to claim 1, wherein The first layer has a plurality of particles having an average diameter ranging from 0.5 μm to 1 μm, and the volume percent porosity of the first layer ranges from 10% to 30%, The second layer has a bimodal particle size distribution, wherein the bimodal particle size distribution has a first mode diameter in a range of 0.5 μm to 2 μm and a second mode diameter in a range of 4 μm to 20 μm, the volume percent porosity of the second layer is in a range of 20% to 60%, and The third layer has a plurality of particles having an average diameter ranging from 0.5 μm to 2 μm, and the volume percent porosity of the third layer ranges from 5% to 30%.

3. The coated component according to claim 1, wherein The first ceramic material, the second ceramic material, and the third ceramic material have the same chemical composition.

4. The coated component according to claim 1, wherein The thickness of the first layer ranges from 2.5 μm to 15 μm.

5. The coated component according to claim 1, wherein The thickness of the second layer ranges from 25 μm to 50 μm.

6. The coated component according to claim 1, wherein The thickness of the third layer ranges from 2.5 μm to 15 μm.

7. The coated component according to claim 1, wherein Each layer includes a binder.

8. The coated component according to claim 1, wherein Each layer comprises a binder containing silica.

9. The coated component according to claim 1, wherein When the coated parts were exposed to a hot air jet at a temperature of 1100 degrees Fahrenheit and a velocity of 104 L / min for one hour, the coated parts lost less than 7 wt% of the coating mass.

10. The coated component according to claim 1, wherein The first ceramic material, the second ceramic material and the third ceramic material are each independently selected from the formula (1) A x E y L z MO u A metal oxide, wherein A is one or more alkaline earth elements selected from magnesium, calcium, strontium and barium; x is in the range of 0 to 1; E is one or more alkali metals selected from lithium, sodium and potassium; y is in the range of 0 to 1; L is one or more lanthanoid elements selected from lanthanum, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, ytterbium and lutetium; z is in the range of 0 to 1; M is one or more elements selected from titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, ruthenium, rhodium, palladium, silver, tantalum, tungsten, rhenium, iridium, platinum, gold and bismuth; O is oxygen; and u is in the range of 0.95 to 6.

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