JP2019099921A - Method for forming porous heat-insulation coating - Google Patents

Abstract

To provide a method for forming a porous heat-insulation coating.SOLUTION: There is provided a method (10) for controlling a porosity parameter of a porous heat-insulation coating (130). The method includes setting a raw material (121) on a substrate (110) to form the porous heat-insulation coating (130). The raw material (121) contains a gas formation additive and a heat-insulation coating material (112). A setting step (12) further includes controlling the porosity parameter of the porous heat-insulation coating (130 by controlling a feed rate of the raw material (121), a content of the gas formation additive in the raw material (121), temperature of the raw material (120) setting on the substrate (110) or a combination thereof.SELECTED DRAWING: Figure 1

Description

  The present disclosure relates generally to methods for forming porous thermal barrier coatings. More specifically, the present disclosure relates to controlling the porosity parameters of porous thermal barrier coatings.

  Thermal barrier coatings are typically used on articles operating at or exposed to high temperatures. Aviation and land based turbines may include, for example, one or more components protected by a thermal barrier coating. Examples of materials used for thermal barrier coatings include rare earth stabilized zirconia materials such as yttrium stabilized zirconia (YSZ). The rare earth stabilized zirconia material has a thermal conductivity of about 2.2 W / m-K when evaluated as a compact sintered body. YSZ is widely used, in part, as a thermal barrier coating material for gas turbines because of its high temperature performance, low thermal conductivity, and relatively easy deposition. In recent years, there has been an increasing demand for further improvement of the thermal barrier properties in order to reduce the total weight, thickness and amount of materials used to form the thermal barrier coating.

  The thermal conductivity of the thermal barrier coating can also be reduced by increasing the porosity of the coating. Conventionally, thermal barrier coatings can be formed using suitable deposition techniques, such as, for example, by air plasma spraying (APS) or by electron beam physical vapor deposition (EBPVD). Thermal barrier coatings deposited by the APS process can typically have a microstructure characterized by irregular expanded particles surrounded by non-uniform porosity. Thermal barrier coatings deposited by the EBPVD process can provide columnar strain resistant particle structures that may be able to expand and contract without creating stresses that lead to fracture. However, EBPVD processes may require more capital than APS processes. Thus, there is a need for an improved coating process that can control the porosity of the thermal barrier coating, thereby controlling the thermal conductivity of the thermal barrier coating.

U.S. Pat. No. 9,527,109 B2

  One embodiment of the present disclosure relates to a method of forming a porous thermal barrier coating by disposing a source material on a substrate. The source material comprises a gas forming additive and a thermal barrier coating material. The placement step comprises controlling the feed rate of the source material, the amount of gas forming additive in the source material, the temperature of the source material disposed on the substrate, or the porosity of the porous thermal barrier coating by controlling the combination thereof It further includes controlling the parameters.

  Another embodiment of the present disclosure relates to a method of forming a porous thermal barrier coating by disposing a source material on a substrate using an air plasma spray process. The source material comprises a gas forming additive and a thermal barrier coating material. The placing step further comprises controlling the porosity parameter of the porous thermal barrier coating by controlling the temperature of the deposited source material on the substrate using an auxiliary heat source.

  Another embodiment of the present disclosure relates to a method of forming a porous thermal barrier coating comprising graded porosity. The method includes disposing a source material on a substrate to form a porous thermal barrier coating, wherein the source material comprises a gas forming additive and a thermal barrier coating material. Placing the thermal barrier coating the graded porosity by controlling the amount of gas forming additive in the source material, the temperature of the source material disposed on the substrate using an auxiliary heat source, or a combination thereof Including forming.

  These and other features, aspects, and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawings. In the accompanying drawings, like numerals represent like parts throughout the drawings.

FIG. 7 illustrates a method of forming a porous thermal barrier coating, according to one embodiment of the present disclosure. FIG. 7 illustrates a method of forming a porous thermal barrier coating, according to one embodiment of the present disclosure. FIG. 7 illustrates a method of forming a porous thermal barrier coating, according to one embodiment of the present disclosure. FIG. 1 is a schematic cross-sectional view of a porous thermal barrier coating, according to an embodiment of the present disclosure. FIG. 7 is another schematic cross-sectional view of a porous thermal barrier coating, according to an embodiment of the present disclosure. FIG. 1 shows a scanning electron microscope (SEM) micrograph of a porous thermal barrier coating, according to one embodiment of the present disclosure.

  As used herein and throughout the specification and claims, the term "approximation" applies to modify any quantitative expression that can be varied without undue change in the underlying functionality involved can do. Thus, values modified by terms such as "about" are not limited to the exact values specified. In some instances, the term describing an approximation may correspond to the accuracy of the instrument for measuring the value. Here, and throughout the specification and claims, the limitation of the range can be combined and / or replaced, and such range is identified and all encompassed therein, unless context and language indicate otherwise Including subranges of

  In the following specification and claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. As used herein, the term "or" is not meant to be exclusive unless explicitly stated otherwise in context, and refers to at least one of the referenced present components and references Including the case where there may be a combination of components.

  As used herein, the terms "may" and "may be" are designated that they may occur in a series of situations. And / or limit another verb by representing one or more of the abilities, capabilities, or possibilities associated with the limited verb. Thus, the use of "possibly" and "possibly" means that the term to be modified is clearly valid, possible or appropriate to the indicated performance, function, or usage. While indicating, it is contemplated that in some circumstances, the terms to be modified may be valid, possible or not appropriate.

  As used herein, the term "coating" refers to a material disposed on at least a portion of the underlying surface in a continuous or discontinuous manner. Furthermore, the term "coating" does not necessarily mean a uniform thickness of the deposited material, and even though the deposited material has a uniform thickness, it has a non-uniform thickness. It is also good. The term "coating" may refer to a single layer of coating material or to multiple layers of coating material. The coating material may be the same or different in the plurality of layers.

  As used herein, unless otherwise stated, the term "disposed" is intended to mean layers or coatings disposed directly in contact with each other or indirectly by having an intervening layer therebetween. Point to.

  One embodiment of the present disclosure relates to a method of forming a porous thermal barrier coating. The method includes disposing a source material on a substrate to form a porous thermal barrier coating, wherein the source material comprises a gas forming additive and a thermal barrier coating material. The placement step comprises controlling the feed rate of the source material, the amount of gas forming additive in the source material, the temperature of the source material disposed on the substrate, or the porosity of the porous thermal barrier coating by controlling the combination thereof Including controlling the parameters.

  FIG. 1 illustrates a method 10 according to some embodiments of the present disclosure. The method 10 comprises providing a substrate 110 in step 11; forming a raw material material 120 disposed and disposed on the substrate 110 in step 12; and porous in step 13. Forming the thermal barrier coating 130 on the substrate 110.

  Although in FIG. 1 the substrate 110 is shown as having a planar profile for ease of explanation, the substrate 110 may have any suitable geometric shape or profile, for example a complex geometry It may have a geometric shape, a non-planar profile, or a combination of both. As used herein, the term "complex geometric shape" refers to shapes that are not easily or consistently identifiable or reproducible, such as not being square, circular, or rectangular. In some embodiments, substrate 110 may be part of a component exposed to a high temperature environment, such as a turbine engine. In some embodiments, the turbine engine may be an aircraft engine. Alternatively, the turbine engine may be any other type of engine used in industrial applications. Non-limiting examples of such turbine engines include land-based turbine engines used in power plants, turbine engines used in ships, or turbine engines used in oil rigs. Non-limiting examples of turbine engine components include turbine airfoils such as blades and vanes, turbine shrouds, turbine nozzles, combustor components such as buckets, liners and deflectors, heat shields, augmentor hardware of gas turbine engines Hardware and other similar turbine components known to those skilled in the art.

  Substrate 110 can comprise a ceramic matrix composite or a metal superalloy. Non-limiting examples of suitable metal superalloys include iron based superalloys, cobalt based superalloys, nickel based superalloys, or combinations thereof.

The substrate 110 may be a pre-manufactured component of a turbine engine or may be manufactured prior to the placement step. In some embodiments, the step 11 of providing the substrate may include one or more preparatory steps, such as, for example, cleaning, polishing, placing a bond coating, and the like. In some embodiments, the substrate 110 can be coated with a bond coating (not shown) in step 11. The bond coating can be formed from a metal oxidation resistant material that protects the underlying substrate 110 and allows the porous thermal barrier coating 130 to adhere more firmly to the substrate 110. Suitable materials for bond coating include M ₁ CrAlY alloy powder, where M ₁ represents a metal such as iron, nickel, platinum or cobalt. Non-limiting examples of other suitable bond coat materials include metal aluminides such as nickel aluminide, platinum aluminide, or combinations thereof.

  As noted above, source material 121 forms source material 120 disposed and disposed on substrate 110 in step 12. As used herein, the term "raw material" refers to a homogeneous mixture of two or more materials that form a single phase, or the failure of two or more materials to form multiple phases. Refers to a homogeneous mixture. The source material 121 may be in solid form, liquid form, or semi-solid form. In one particular embodiment, the source material 121 is in the form of a powder.

  As mentioned earlier, the source material 121 comprises a gas forming additive and a thermal barrier coating material. In one particular embodiment, the source material 121 comprises a homogeneous mixture of gas forming additive and thermal barrier coating material. In one particular embodiment, the gas forming additive is pre-dissolved in the thermal barrier coating material to form the source material 121. Without being bound by any theory, the porosity parameters of the porous thermal barrier coating 130 are controlled by incorporating a gas forming additive into the source material 121 during the production of the source material 121 (eg, source powder). It is thought that can be done. For example, this can be done by controlling one or more of the amount, size, or distribution of gas forming additives in source material 121.

  As used herein, the term "gas forming additive" is capable of oxidizing at elevated temperatures into a non-reactive and insoluble (with the thermal barrier coating material) gas trapped by the thermal barrier coating material Refers to the material that forms the pores thereby. Examples of suitable gas forming additives include, but are not limited to, graphite, carbides, oxycarbides, nitrides, or combinations thereof. In certain embodiments, the gas forming additive comprises elemental carbon. During or after the placement step, the gas forming additive may be a gas, such as carbon monoxide, carbon dioxide, nitrous oxide, or any other, depending on the composition of the gas forming additive used, as described in more detail below. Form a suitable gas. The insoluble gas is trapped in the thermal barrier coating during the placement or post-placement step, thereby forming pores. In some embodiments, a substantial amount of gas formed is trapped in the thermal barrier coating material. The term "substantial amount of gas" as used herein refers to at least 90% by volume of the gas formed. This is in contrast to the fugitive material used to form the porous coating, where the coating material is subjected to elevated temperatures such that the fugitive material decomposes or oxidizes, and the resulting gas is released from the coating And thereby create pores.

  As used herein, the term "thermal barrier coating" refers to a coating that includes a material capable of reducing the flow of heat to the underlying substrate of the article, ie, forming a thermal barrier. . The composition of the porous thermal barrier coating with respect to the type and amount of thermal barrier coating material is the composition of the adjacent bond coat layer (if present), the coefficient of thermal expansion (CTE) characteristics desired for the thermal barrier coating, and the thermal barrier It may depend on one or more factors, including the thermal barrier properties desired for the coating.

  Non-limiting examples of suitable thermal barrier coating materials include zirconia, pyrochlore, or combinations thereof. In some embodiments, the thermal barrier material is chemically stabilized zirconia (eg, metal oxide blended with zirconia), such as yttria stabilized zirconia, ceria stabilized zirconia, calcia stabilized zirconia, Scandia stabilized zirconia, magnesia stabilized zirconia, india stabilized zirconia, ytterbia stabilized zirconia, lanthana stabilized zirconia, gadolinia stabilized zirconia, as well as mixtures of such stabilized zirconia.

  In certain embodiments, the thermal barrier coating material comprises yttria stabilized zirconia. Suitable yttria stabilized zirconia may comprise about 1 wt% to about 20 wt% yttria (based on the combined weight of yttria and zirconia), more typically about 3 wt% to about 10 wt% yttria. An exemplary yttria stabilized zirconia thermal barrier coating comprises about 7 wt% yttria and about 93 wt% zirconia. These chemically stabilized zirconias further reduce the thermal conductivity of the thermal barrier coating by using second metals such as dysprosia, erbia, europia, gadolinia, neodymia, praseodymia, uranias, and hafnia (e.g. And one or more of lanthanide or actinide) oxides.

  As used herein, the term "porous thermal barrier coating" refers to a coating comprising a plurality of pores. The term "porosity parameter of the porous thermal barrier coating" as used herein refers to the pore size, pore size distribution, number of pores, or number of pores in the porous thermal barrier coating 130, or Refers to one or more of the pore microstructures. The pore size provides an indication of the median or mean diameter of the pores in the porous thermal barrier coating 130. The pore size distribution provides a quantitative description of the range of pore sizes present over the length, width and thickness of the porous thermal barrier coating 130. Pore volume is the percentage of the volume occupied by the plurality of pores in the total volume occupied by the porous thermal barrier coating 130, also referred to as the "total porosity" of the porous thermal barrier coating 130. By varying one or more of the porosity parameters described above, the overall porosity of the plurality of pores in the porous thermal barrier coating 130 can be controlled. The pore size, pore shape, number of pores, pore size distribution, or one or more of the pore microstructures in the porous thermal barrier coating 130 may be controlled using the methods described in the present disclosure it can.

  In some embodiments, the average pore size of the plurality of pores in the porous thermal barrier coating 130 is in the range of about 0.1 microns to about 25 microns. In some embodiments, the average pore size of the plurality of pores in the porous thermal barrier coating 130 ranges from about 0.25 microns to about 5 microns. The plurality of pores in the porous thermal barrier coating 130 can be characterized by any suitable shape. In certain embodiments, the shape of the pores in the porous thermal barrier coating may be substantially spherical. In some embodiments, the porosity of the spheroid in the porous thermal barrier coating 130 can provide a strain resistant microstructure, whereby the thermal barrier coating lasts longer under gas turbine operating conditions Allow to work.

  Referring again to FIG. 1, in step 12, the source material 121 is disposed on the substrate 110 using a suitable device 115. Raw materials 121 are physical vapor deposition (PVD), vapor deposition such as electron beam physical vapor deposition (EBPVD); air plasma spraying (APS), suspension plasma spraying (SPS), and plasma spraying such as vacuum plasma spraying (VPS); high speed oxygen Fuel (HVOF) spraying, explosion, or any other thermal spray deposition method such as wire spraying; chemical vapor deposition (CVD), sol-gel method, or any of a variety of techniques, including combinations of two or more of the above mentioned techniques Directly on the bond coating (if present) or on the substrate 110.

  The particular technology used to place, deposit or form the porous thermal barrier coating 130 is the composition of the porous thermal barrier coating 130, the thickness, and the physical structure desired for the porous thermal barrier coating 130 It may depend on one or more. In one particular embodiment, the source material 121 is disposed using plasma spray technology, in particular, APS technology. As mentioned earlier, the gas forming additive and the thermal barrier coating material are co-deposited as the source material 121 on the substrate 110 or bond coating (if present). In some embodiments, co-deposition blends, mixes or combines the gas forming additive and the thermal barrier coating material together (eg, as a powder) and then deposits the mixture deposited on the substrate / bond coating It can be achieved by providing. Blending or mixing of the gas forming additive and the thermal barrier coating material can be done prior to feeding the source material to the deposition apparatus 115 (eg, APS gun), or can be done in the deposition apparatus 115 itself, internally Form the raw material. In one particular embodiment, the gas forming additive is mixed and dissolved in the thermal barrier coating material prior to supplying the source material 121 to the deposition apparatus 115. As used herein, the term "placed source material" as used herein is a source material as deposited, ie, a source material that has not been subjected to additional steps (eg, heating), or Source materials that have been subjected to additional steps (eg, heating via an auxiliary heat source). The term "disposed source material" as used herein is distinguished from "porous thermal barrier coating", whereby in "disposed source material" the thermal barrier coating material is partially or It may be completely molten and the pores may still not be trapped in the coating.

  The disposing step 12 is performed by supplying the raw material 121, the amount of the gas forming additive in the raw material 121, or the temperature of the raw material 120 disposed on the substrate 110 to form the porous thermal barrier coating 130. Further including controlling the By controlling one or more of these parameters, the porosity parameter (and hence the total porosity) of the porous thermal barrier coating 130 is controlled. Without being bound by any theory, uncontrolled, non-spheroidal, or randomly distributed porosity in the porous thermal barrier coating 130 may occur in the absence of this control step. it is conceivable that.

  In some embodiments, the porosity parameter of the porous thermal barrier coating 130 is controlled by controlling the feed rate of the source material 121 and / or the amount of gas forming additive in the source material 121. The term "feed rate" as used herein refers to the deposition rate of the source material 121 on the substrate 110 by using a suitable deposition apparatus 115. In embodiments where the source material is deposited using an APS process, the term "feed rate" refers to the spray rate of source material 121. In some embodiments, the porosity parameter of the porous thermal barrier coating 130 is controlled by controlling the amount of gas forming additive in the source material 121 in the range of about 0.1 wt% to about 10 wt% . In some embodiments, the porosity parameter of the porous thermal barrier coating 130 is controlled by controlling the amount of gas forming additive in the source material 121 in the range of about 0.5 wt% to about 5 wt% . In some embodiments, as described in more detail below, the amount of gas forming additive in the source material 121 is such that the disposed source material 120 includes a graded content of gas forming additive. A graded porosity may be formed in the resulting porous thermal barrier coating 130 which may be varied over time. In such embodiments, the term "amount of gas forming additive" refers to the average amount of gas forming additive in the feedstock 121 over the entire duration of the placement step.

  In some embodiments, the porosity parameter of the porous thermal barrier coating 130 is controlled by controlling the feed rate of the source material 121 in the range of about 2.5 gm / min to about 100 gm / min. In some embodiments, the porosity parameter of the porous thermal barrier coating 130 is controlled by controlling the feed rate of the source material 121 in the range of about 20 gm / min to about 50 gm / min. The feed rate can be controlled by using a valve or other suitable method. This is in contrast to the method used to form the porous thermal barrier coating, as the feed rate or amount of gas forming additive in the source material is not controlled, so it is random and uncontrolled. Porosity can occur.

  In some embodiments, the porosity parameters of the porous thermal barrier coating 130 are controlled by controlling the temperature of the source material 120 disposed on the substrate 110. The temperature of the source material 120 disposed on the substrate 110 is the temperature of the source material 121 before deposition (for example, by preheating the source material), the deposition temperature (for example, when using APS for deposition) Control may be by controlling one or more of: thermal spray temperature by using an auxiliary heat source during deposition, or the temperature of the substrate 110 on which the source material is being deposited. In certain embodiments, the temperature of the source material 120 disposed on the substrate 110 is controlled by a combination of substrate preheating and maintenance of the disposed source material temperature.

  In some embodiments, the source material 120 disposed on the substrate 110 is heated to a temperature higher than the temperature that the substrate 110 can withstand. As used herein, the term "the temperature that the substrate can withstand" refers to the temperature above which the substrate begins to deform, melt, or change shape. In some embodiments, the disposed feedstock material may be heated to a temperature similar to the turbine engine operating temperature. Depositing the source material and heating to a temperature similar to the engine operating temperature can reduce interface coating stress, which can potentially improve the life of the engine's thermal barrier coating at that temperature. In some embodiments, source material 120 disposed on substrate 110 is heated to a temperature in the range of about 1000 ° C. to about 1500 ° C. In one particular embodiment, the source material 120 disposed on the substrate 110 is heated to a temperature in the range of about 1150 ° C. to about 1300 ° C.

  The disposed source material 120 may be heated using an auxiliary heat source. The term "auxiliary heat source" refers to a heat source used in addition to the main device used to place the source material 121. For example, if the source material is placed using APS technology, the APS device can include a separate main heat source separate from the supplemental heat source. Suitable supplemental heat sources include, but are not limited to, infrared (IR) sources, plasma sources, inductors, or combinations thereof. In some embodiments, the supplemental heat source is a plasma source different from the plasma source used in the APS process. In certain embodiments, the supplemental heat source comprises an induction coil.

  Another embodiment of the present disclosure relates to a method of forming a porous thermal barrier coating using an auxiliary heat source. The method includes disposing a source material on a substrate using an air plasma spray process to form a porous thermal barrier coating, wherein the source material comprises a gas forming additive and a thermal barrier coating material. The placing step includes controlling the porosity parameter of the porous thermal barrier coating by controlling the temperature of the deposited source material on the substrate using an auxiliary heat source.

  FIG. 2 shows a method 20 according to an embodiment of the present disclosure. The method 20 comprises providing a substrate 110 in step 14 and forming a source material 120 disposed and disposed on the substrate 110 using the APS device 115 in step 15; Forming the porous thermal barrier coating 130 on the substrate 110 in step 16; The method further includes, at step 15, controlling the temperature of the disposed source material using the supplemental heat source 125. Non-limiting examples of suitable supplemental heat sources are described herein above. Furthermore, although FIG. 2 shows a single auxiliary heat source 125, it should be noted that one or more heat sources 125 can be used depending on the size and shape of the substrate. Additionally, one or more of the configuration of the supplemental heat source 125, the placement of the supplemental heat source 125, and the proximity of the supplemental heat source 125 to the substrate 110 may vary depending on the degree of heating required.

  With reference now to FIGS. 1 and 2, in some embodiments, heating of disposed raw material 120 preheats the substrate 110, simultaneously arranging and heating the raw material 121, or arranging steps. This is done by one or more of heating the source material 120 located after 12,15. In certain embodiments, heating of the disposed source material 120 is performed by preheating the substrate 110 prior to the placing steps 12, 15. In some such cases, the substrate 110 may be preheated to a first temperature using an auxiliary heat source 125, and the source material 121 may be deposited on the preheated substrate . The first temperature is sufficient to melt the thermal barrier coating material or to maintain the molten thermal barrier coating material in a molten state, but also below the temperature that the substrate 110 can withstand. Good. In some embodiments, the source material can be further heated to a second temperature using the supplemental heat source 125 during the placement steps 12, 15. The second temperature is sufficient to cause oxidation of the gas forming additive, thereby forming a gas in the molten thermal barrier coating material, but may be higher than the temperature the substrate can withstand . For example, in the case of a nickel or cobalt based superalloy, the supplemental heat source can heat the disposed source material 120 to a temperature above the melting point of these superalloys such that a gas is formed.

  The method may further include cooling the disposed source material 120 to form a porous thermal barrier coating 130 in steps 13, 16. In some embodiments, by using a preheated substrate, the gas forming additive comprising source material 121 is deposited at a temperature such that the gas forming additive oxidizes to form a gas. This gas is formed while the source material is still melting and bubbles can form pores. In some embodiments, the cooling rate of the disposed source material 120 is such that the pores are confined within the disposed source material 120. As mentioned earlier, the porosity of these confined pores can be controlled using the methods described herein. In some embodiments, as discussed further below, the supplemental heat source 125 may be further controlled to provide heating from the supplemental heat source 125 to produce graded porosity in the porous thermal barrier coating 130. Good.

  Another embodiment of the present disclosure relates to a method of forming a porous thermal barrier coating comprising graded porosity. The method includes disposing a source material on a substrate to form a porous thermal barrier coating, wherein the source material comprises a gas forming additive and a thermal barrier coating material. Placing the thermal barrier coating the graded porosity by controlling the amount of gas forming additive in the source material, the temperature of the source material disposed on the substrate using an auxiliary heat source, or a combination thereof Including forming.

  The term "graded porosity" as used herein refers to the change in volume percent of the porous thermal barrier coating 130 occupied by the plurality of pores across the thickness of the porous thermal barrier coating 130. For a particular area of porous thermal barrier coating 130, the volume percentage occupied by the plurality of pores can be referred to as the "porosity" in that particular area. Furthermore, the term gradient porosity encompasses discrete changes in porosity, continuous changes in porosity, or a combination thereof. For example, in some embodiments, the method may include forming a graded porosity in the porous thermal barrier coating 130 such that the porosity is greater than that of the substrate 110 (or bond coating, if present). ) Continuously increases or decreases over the thickness of the porous thermal barrier coating 130 from the region disposed in proximity to the surface of the porous thermal barrier coating 130. In some other embodiments, the source material 121 may be disposed on the substrate 110 (or bond coating, if present) in the form of discrete layers, and the resulting porous barrier There is a gradual change (increase or decrease) in porosity across the different layers of the thermal coating 130. In certain embodiments, the method includes forming a porous thermal barrier coating 130 such that an area proximate to the substrate 110 (or bond coating, if present) and the porous thermal barrier coating 130 The surface is substantially free of porosity. The middle region can have a graded porosity that can be discrete or continuous. Additionally, the porosity of the intermediate region may be increased or decreased depending on the desired properties of the porous thermal barrier coating. Without being bound by any theory, it is believed that the graded porosity across the thickness of the porous thermal barrier coating 130 can provide the desired performance characteristics, depending on the end use application. For example, the erosion or impact resistance of the coating can be enhanced by minimizing the porosity of the layer / region close to the surface of the porous thermal barrier coating. In some other applications, the porous surface of the thermal barrier coating may be desirable, for example, to improve the sacrificial properties of the coating.

  The porosity of the porous thermal barrier coating 130 of the different regions / layers of the thermal barrier coating 130 changes the number of pores of the different regions / layers and / or the average diameter of the plurality of pores of the different regions / layers It can be changed by In certain embodiments, the graded porosity across the thickness of the porous thermal barrier coating is the amount of gas forming additive in the feedstock material, the temperature of the feedstock material disposed on the substrate using an auxiliary heat source, or It is formed by controlling their combination.

  Returning to FIGS. 1 and 2, in some embodiments, the graded porosity across the thickness of the porous thermal barrier coating 130 is formed, for example, by controlling the amount of gas forming additive in the source material 121 can do. By varying the amount of gas forming additive in the source material 121, the amount of gas forming additive in the source material 120 disposed over the duration of the placement steps 12, 15 can be varied. Thus, a graded content of the gas-forming additive in the arranged source material 120 is obtained. This graded content of gas forming additive in the source material 120 disposed may produce graded porosity upon oxidation. In some embodiments, the amount of gas forming additive in the source material 121 provides a plurality of feeds containing the changing gas forming additive to the deposition apparatus 115 and the feed to the deposition apparatus 115 It can be changed by control.

  Still referring to FIG. 2, in some other embodiments, the graded porosity across the thickness of the porous thermal barrier coating 130 may be formed, for example, by controlling the temperature of the disposed source material 120 it can. In such embodiments, the supplemental heat source 125 can be turned on or off during the placement step 15 depending on the desired slope of porosity. For example, for layers / regions where minimal porosity is desired, the supplemental heat source 125 can be turned off, thereby minimizing the formation of gas in these layers / regions.

  Referring now to FIG. 3, a method 30 of forming a porous thermal barrier coating 130 with graded porosity is shown. The method 30 comprises providing the substrate 110 in step 31, placing the thermal barrier coating material 112 on the substrate 110 in step 32, and in step 33 the source material 121 on the thermal barrier coating material 112. Forming a plurality of layers of disposed source material (120 ′, 120 ′ ′), and in step 34, the outermost layer 120 ′ of the source material 120 ′ ′ having the thermal barrier coating material 112 disposed thereon. And, in step 35, forming a porous thermal barrier coating 130 on the substrate 110. The method further includes, in step 33, controlling the temperature of the disposed source material 120 ', 120' 'using the supplemental heat source 125. Non-limiting examples of suitable supplemental heat sources are described herein above. In some embodiments, the supplemental heat source 125 can be used in steps 32 and 34 to place the thermal barrier coating material 112 on the substrate 110. Although FIG. 3 shows the two layer disposed raw material (120 ′, 120 ′ ′), the multiple layer disposed raw material is a thermal barrier coating material depending on the requirement of total porosity Note that it may be on 112.

  In some embodiments, the amount of gas forming additive in the disposed feedstock material 120 'may be different than the amount of disposed feedstock material 120 ". As mentioned earlier, the amount of gas forming additive in the source material 120 disposed can be varied by changing the amount of gas forming additive in the source material 121. This change in the amount of gas forming additive in the different layers may result in a change in the overall porosity of each layer, thereby producing a porous thermal barrier coating 130 with graded porosity. Thus, in such embodiments, the porous thermal barrier coating 130 includes multiple layers (112, 120 ', 120 ") such that the porosity of each layer is different.

  In some embodiments, the temperature of the disposed source material 120 'may be different than the temperature of the disposed source material 120' '. As mentioned earlier, the temperature of the source material 120 placed can be varied by controlling the auxiliary heat source 125. This change in temperature in the different layers may result in a change in the overall porosity of each layer, thereby producing a porous thermal barrier coating 130 with graded porosity. Thus, in such embodiments, the porous thermal barrier coating 130 includes multiple layers (112, 120 ', 120 ") such that the porosity of each layer is different.

  4 and 5 show schematic cross-sectional views of a porous thermal barrier coating 130 including a plurality of pores 132 formed using methods according to some embodiments of the present disclosure. In some embodiments, controlling the porosity parameter of the porous thermal barrier coating 130 comprises an average pore size of the plurality of pores 132 in the porous thermal barrier coating 130 of about 0.1 microns to about 25 microns. Including controlling in the range of In some embodiments, controlling the porosity parameter of the porous thermal barrier coating 130 comprises an average pore size of the plurality of pores 132 in the porous thermal barrier coating 130 of about 0.25 microns to about 5 microns. Including controlling in the range of In some embodiments, controlling the porosity parameter of the porous thermal barrier coating 130 comprises an average pore volume of the plurality of pores 132 in the porous thermal barrier coating 130 of about 1% by volume to about 10 volumes. Including controlling in the range of%. In some embodiments, controlling the porosity parameter of the porous thermal barrier coating 130 comprises about 5% by volume to about 10 volumes of the average pore volume of the plurality of pores 132 in the porous thermal barrier coating 130. Including controlling in the range of%.

  In some embodiments, controlling the porosity parameter of the porous thermal barrier coating 130 includes controlling the pore microstructure of the plurality of pores 132 in the porous thermal barrier coating 130. In some embodiments, the porous thermal barrier coating 130 includes a plurality of pores 132 such that at least some of the plurality of pores are in the particle. The term "intraparticle" as used herein means that the pore is present inside the particle. In some embodiments, the porous thermal barrier coating 130 has a plurality of pores such that at least some of the plurality of pores are between particles (present between particles) or at grain boundaries. The pores 132 are included. In certain embodiments, more than 50% of the plurality of pores are in particles. In certain embodiments, more than 80% of the plurality of pores are in particles.

  FIG. 4 shows a schematic view of the microstructure of the formed porous thermal barrier coating 130 according to some embodiments of the present disclosure. The microstructure of the porous thermal barrier coating 130 shown in FIG. 4 is characterized by particles 134 having a plurality of grain boundaries 136. The microstructure further includes a plurality of pores 132 (pores in the particles) present inside the particles 134.

  FIG. 5 shows another schematic of the microstructure of the formed porous thermal barrier coating 130, according to some embodiments of the present disclosure. The microstructure of the porous thermal barrier coating 130 shown in FIG. 5 is characterized by particles 134 having a plurality of grain boundaries 136. The microstructure further includes a plurality of pores 132 (pores in the particles) present inside the particle 134 and a plurality of pores 138 (pores in the particles) at or between the grain boundaries 136.

  FIG. 6 shows a scanning electron microscope (SEM) micrograph of a porous thermal barrier coating 130 formed by coating a mixture of YSZ and elemental carbon using an APS process. The microstructure of the porous thermal barrier coating 130 shown in FIG. 6 is characterized by particles 134 having a plurality of grain boundaries 136. The microstructure further includes a plurality of substantially spherical pores 132 (pores in the particles) present inside the particles 134. Pores 132 are produced by the trapped carbon-containing gas.

  Without being bound by any theory, as the gas (eg carbon monoxide, carbon dioxide, etc.) is produced from the decomposition of the gas forming additive at high temperature, the gas forming additive (eg It is believed that the presence of elemental carbon) may result in additional porosity. Because these gases are insoluble in the thermal barrier coating material, they can be trapped within the thermal barrier coating material. The pressure exerted by the entrapped gas on the surrounding thermal barrier material causes the coarsening of the pores, such that the thermal barrier coating retains its fine porosity and the thermal barrier coating's microstructure can be thermally stabilized. And redistribution in the microstructure can be suppressed. Controlled porosity may further result in the lower thermal conductivity of the porous thermal barrier coating. Thus, in some such embodiments, the porous thermal barrier coating can enhance thermal protection as the temperature gradient across the coating is higher for the same coating thickness. Alternatively, turbine engine components can be designed for thinner thermal barrier coatings and lower cooling air flow rates, if applicable. This can reduce processing and material costs and can promote component life and engine efficiency.

The foregoing examples are merely illustrative and serve to exemplify only some of the features of the present disclosure. Accordingly, it is the applicant's intention that the scope of the appended claims should not be limited by the selection of examples utilized to explain the features of the present disclosure. As used in the claims, the word "comprise" and its grammatical variations are various and different ranges such as, but not limited to, "consisting essentially of" and "consisting of" Also logically contains and includes the phrase As required, ranges are given, which cover all subranges between them. Variations to these ranges would be suggested to one of ordinary skill in the art as such, and if not yet generally released, those variations should be construed as falling within the scope of the appended claims, if possible. It should be expected that it should be. Advances in science and technology will enable equivalents and substitutes that are not now contemplated due to language inaccuracies, and these variations are also, where possible, the appended claims. It is also expected that it should be interpreted as being included in.
[Embodiment 1]
A method (10, 20, 30) of forming a porous thermal barrier coating (130), comprising
Disposing a source material (121) on a substrate (110) to form said porous thermal barrier coating (130) (12, 15), said source material (121) comprising a gas forming additive A thermal barrier coating material (112), said disposing (12, 15) comprising feeding rate of a raw material (121), amount of said gas forming additive in said raw material (121), said base Control the porosity parameter of the porous thermal barrier coating (130) by controlling the temperature of the placed raw material (120, 120 ', 120'') on the material (110), or a combination thereof Methods (10, 20, 30).
Embodiment 2
Said controlling the porosity parameter of the porous thermal barrier coating (130) using the auxiliary heat source (125) on the arranged raw material (120, 120 ') on the substrate (110), The method (10, 20, 30) according to embodiment 1, comprising controlling (33) said temperature of 120 '').
Embodiment 3
Embodiment 2 wherein the disposed source material (120, 120 ', 120'') on the substrate (110) is heated to a temperature higher than the temperature the substrate (110) can withstand. The method described in 10. (10, 20, 30).
Embodiment 4
Embodiment 4. The method according to embodiment 3, wherein the disposed source material (120, 120 ′, 120 ′ ′) on the substrate (110) is heated to a temperature in the range of about 1000 ° C. to about 1500 ° C. 10, 20, 30).
Embodiment 5
The controlling of the porosity parameter of the porous thermal barrier coating (130) may range the amount of the gas forming additive in the source material (121) from about 0.1 wt% to about 10 wt%. The method according to embodiment 1, comprising controlling (10, 20, 30).
[Embodiment 6]
Said controlling said porosity parameter of said porous thermal barrier coating (130) comprises controlling the feed rate of the source material (121) in the range of about 2.5 gm / min to about 100 gm / min. The method according to embodiment 1 (10, 20, 30).
[Embodiment 7]
The method (10, 20, 30) according to embodiment 1, wherein the gas forming additive comprises graphite, carbides, oxycarbides, nitrides, or a combination thereof.
[Embodiment 8]
The method (10, 20, 30) according to embodiment 1, wherein said gas forming additive comprises elemental carbon.
[Embodiment 9]
The method (10, 20, 30) according to embodiment 1, wherein the thermal barrier coating material (112) comprises yttria stabilized zirconia.
[Embodiment 10]
The method (10, 20, 30) according to embodiment 1, wherein the source material (121) is disposed on the substrate (110) using an air plasma spray process.
[Embodiment 11]
The method according to embodiment 1, wherein the porosity parameter comprises mean pore size, mean pore volume, pore size distribution, pore microstructure, or a combination thereof (10, 20, 30).
Embodiment 12
The porous thermal barrier coating (130) comprises the plurality of pores (132) such that at least some pores (132) of the plurality of pores (132) are in particles. Methods described (10, 20, 30).
Embodiment 13
The controlling of the porosity parameter of the porous thermal barrier coating (130) may result in an average pore size of the plurality of pores (132) in the porous thermal barrier coating (130) of about 0.1 micron to The method (10, 20, 30) according to embodiment 1, comprising controlling in the range of about 25 microns.
Embodiment 14
The controlling of the porosity parameter of the porous thermal barrier coating (130) comprises between about 5% by volume of the average pore volume of the plurality of pores (132) in the porous thermal barrier coating (130) The method according to embodiment 1, comprising controlling in the range of about 10% by volume (10, 20, 30).
Embodiment 15
The method according to claim 1, wherein said controlling said porosity parameter of said thermal barrier coating (130) further comprises forming a graded porosity across the thickness of said thermal barrier coating (130) (10 20, 30).
Embodiment 16
A method (10, 20, 30) of forming a porous thermal barrier coating (130), comprising
A source material (121) is disposed on a substrate (110) using an air plasma spray process to form (12, 15) said porous thermal barrier coating (130), said source material (121) ) Comprises a gas forming additive and a thermal barrier coating material (112), said placing (12, 15) using said auxiliary heat source (125) said placing on said substrate (110) Controlling the porosity parameter of said porous thermal barrier coating (130) by controlling (33) the temperature of the raw material material (120, 120 ', 120'') 30).
[Embodiment 17]
17. The method according to embodiment 16, wherein the disposed raw material (120, 120 ′, 120 ′ ′) on the substrate (110) is heated to a temperature in the range of about 1000 ° C. to about 1500 ° C. 10, 20, 30).
[Embodiment 18]
Embodiment 17. The method (10, 20, 30) according to embodiment 16, wherein the gas forming additive comprises elemental carbon.
[Embodiment 19]
17. The method (10, 20, 30) according to embodiment 16, wherein the thermal barrier coating material (112) comprises yttria stabilized zirconia.
[Embodiment 20]
A method (10, 20, 30) of forming a porous thermal barrier coating (130) comprising graded porosity, comprising
Disposing a source material (121) on a substrate (110) to form said porous thermal barrier coating (130) (12, 15), said source material (121) comprising a gas forming additive A thermal barrier coating material (112), said disposing (12, 15) comprising the amount of said gas forming additive in said source material (121), said substrate using an auxiliary heat source (125) (110) forming the graded porosity in the thermal barrier coating by controlling the temperature of the disposed source material (120, 120 ′, 120 ′ ′), or a combination thereof, Method.

10 method 20 method 30 method 110 substrate 112 thermal barrier coating material 115 deposition apparatus, APS apparatus 120 disposed raw material material 120 ′ disposed raw material material 120 ′ ′ disposed raw material material, outermost layer 121 raw material material 125 auxiliary heat source 130 porous thermal barrier coating 132 pore 134 particle 136 grain boundary 138 pore

Claims (15)

A method (10, 20, 30) of forming a porous thermal barrier coating (130), comprising
Disposing a source material (121) on a substrate (110) to form said porous thermal barrier coating (130) (12, 15), said source material (121) comprising a gas forming additive A thermal barrier coating material (112), said disposing (12, 15) comprising feeding rate of a raw material (121), amount of said gas forming additive in said raw material (121), said base Control the porosity parameter of the porous thermal barrier coating (130) by controlling the temperature of the placed raw material (120, 120 ', 120'') on the material (110), or a combination thereof Methods (10, 20, 30).   Said controlling the porosity parameter of the porous thermal barrier coating (130) using the auxiliary heat source (125) on the arranged raw material (120, 120 ') on the substrate (110), The method (10, 20, 30) according to claim 1, comprising controlling (33) the temperature of 120 ").   The material material (120, 120 ′, 120 ′ ′) placed on the substrate (110) is heated to a temperature higher than the temperature the substrate (110) can withstand. The method described in 10. (10, 20, 30).   The method according to claim 3, wherein the disposed raw material (120, 120 ', 120' ') on the substrate (110) is heated to a temperature in the range of about 1000 ° C to about 1500 ° C. 10, 20, 30).   The controlling of the porosity parameter of the porous thermal barrier coating (130) may range the amount of the gas forming additive in the source material (121) from about 0.1 wt% to about 10 wt%. The method (10, 20, 30) according to claim 1, comprising controlling.   Said controlling said porosity parameter of said porous thermal barrier coating (130) comprises controlling the feed rate of the source material (121) in the range of about 2.5 gm / min to about 100 gm / min. Method according to claim 1 (10, 20, 30).   The method (10, 20, 30) according to claim 1, wherein the gas forming additive comprises graphite, carbides, oxycarbides, nitrides, or combinations thereof.   The method (10, 20, 30) according to claim 1, wherein the gas forming additive comprises elemental carbon.   The method (10, 20, 30) according to claim 1, wherein the thermal barrier coating material (112) comprises yttria stabilized zirconia.   The method (10, 20, 30) according to claim 1, wherein the source material (121) is disposed on the substrate (110) using an air plasma spray process.   The method (10, 20, 30) according to claim 1, wherein the porosity parameter comprises an average pore size, an average pore volume, a pore size distribution, a pore microstructure, or a combination thereof.   The porous thermal barrier coating (130) comprises the plurality of pores (132) such that at least some of the plurality of pores (132) are in particles (132). Methods described (10, 20, 30).   The controlling of the porosity parameter of the porous thermal barrier coating (130) may result in an average pore size of the plurality of pores (132) in the porous thermal barrier coating (130) of about 0.1 micron to A method (10, 20, 30) according to claim 1, comprising controlling in the range of about 25 microns.   The controlling of the porosity parameter of the porous thermal barrier coating (130) comprises between about 5% by volume of the average pore volume of the plurality of pores (132) in the porous thermal barrier coating (130) The method (10, 20, 30) according to claim 1, comprising controlling in the range of about 10% by volume.   The method of claim 1, wherein the controlling the porosity parameter of the porous thermal barrier coating (130) further comprises forming a graded porosity across the thickness of the porous thermal barrier coating (130). Method (10, 20, 30).