WO1999065626A1 - Dispositif et procede de production d'enduits constituant une barriere thermique - Google Patents

Dispositif et procede de production d'enduits constituant une barriere thermique Download PDF

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Publication number
WO1999065626A1
WO1999065626A1 PCT/US1999/013450 US9913450W WO9965626A1 WO 1999065626 A1 WO1999065626 A1 WO 1999065626A1 US 9913450 W US9913450 W US 9913450W WO 9965626 A1 WO9965626 A1 WO 9965626A1
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Prior art keywords
substrate
angle
evaporant
incidence
depositing
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PCT/US1999/013450
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English (en)
Inventor
Derek D. Hass
Haydn N. G. Wadley
James F. Groves
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University Of Virginia Patent Foundation
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Priority to AU46839/99A priority Critical patent/AU4683999A/en
Publication of WO1999065626A1 publication Critical patent/WO1999065626A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/225—Oblique incidence of vaporised material on substrate
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/08—Oxides
    • C23C14/083—Oxides of refractory metals or yttrium
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/228—Gas flow assisted PVD deposition

Definitions

  • the present invention relates to the field of thermal barrier coatings, and more
  • TBC Thermal barrier coating
  • TBC systems have been important to the development of
  • TBC coating systems typically consist of three layers, a thermally insulating
  • top layer a thermally grown oxide
  • TGO thermally grown oxide
  • the top TBC layer is typically a porous ceramic layer formed from a low thermal conductivity material such as zirconia (ZrO 2 ), stabilized by yttria (Y 2 O 3 ), ceria (CeO 2 ), magnesia (MgO), or another oxide.
  • the top TBC layer provides thermal insulation to the underlying component, whereas the bond layer oxidizes prior to or during the deposition of the top layer, or in service, to form the thin TGO layer, which typically consists of -alumina.
  • the TGO layer improves the adherence of the top layer to the underlying component, and protects the underlying component from oxidation and hot corrosion.
  • a TBC coating system must have a low thermal conductivity to thermally insulate the underlying component from hot engine gases. It must also be compliant in order to minimize stresses that result during thermal cycling because of the different coefficients of thermal expansion of the TBC coating system and the underlying materials. Minimizing such stresses is important, as they will result in cracking and spalling of the TBC coating system, and failure of the underlying component.
  • the structural performance and thermal properties of TBCs are strongly influenced by the relative amount and orientation of porosity in the top layer.
  • the top layer in order to achieve high in-plane compliance associated with good structural performance, it is desirable that the top layer have a porous microstructure featuring pores or discontinuities extending through the thickness of the layer, Le. in a vertical plane, such as with columnar pores.
  • the top layer preferably will have a microstructure featuring discontinuities or voids which do not extend over the thickness of the layer, but instead extend in a horizontal plane in such a way that the conduction of heat and the propagation of radiant energy are both impeded.
  • the TBC top layer has been produced by one of two processing methods, plasma spray (“PS”) or electron beam-physical vapor deposition (“EB- PND”). Both of these approaches, while useful, suffer from significant disadvantages. Specifically, layers formed using PS systems contain many horizontal pores which result in a low thermal conductivity and, accordingly, good thermal protection properties. However, these disc-like horizontal pores do not contribute to the in-plane compliance and therefore result in poor spallation resistance. Figures la and lb schematically illustrate typical disclike pores aligned in the plane of a PS coating. These pores impede heat flow through the thickness of the coating, resulting in a coating with a low thermal conductivity.
  • PS plasma spray
  • EB- PND electron beam-physical vapor deposition
  • PS coatings can be unreliable and tend to be used only to extend component life, not to increase engine operating temperatures.
  • EB-PVD layers have a columnar microstructure featuring columns separated by elongated inter- columnar voids aligned generally perpendicular to the substrate surface.
  • Such a structure results in a low in-plane stiffness, thus reducing thermomechanical stresses during thermal cycling and resulting in an improved spallation resistance compared to that of layers formed using PS systems.
  • such a structure fails to sufficiently impede heat flow by conduction or radiation, resulting in a higher thermal conductivity and, accordingly, reduced thermal protection.
  • the present invention is directed to an apparatus and method for producing TBC coating systems having both exceptional thermal performance and exceptional structural performance.
  • the method of the present invention generally comprises the steps of providing a substrate, providing a source material to be deposited onto the substrate, and depositing the source material onto the substrate for a period of time T, and at an angle of incidence ⁇ ,, where
  • the angle of incidence is changed to an angle ⁇ 2 , where
  • the source material is deposited until a coating thickness greater than about 1 ⁇ m is achieved. It should be noted that the terms "about” or “approximately,” as used in the present application, are intended to encompass values within ⁇ 25% of the stated value.
  • a coating having a thermally stable (sintering resistant), "zig-zag” shaped microstructure and exceptional structural and thermal properties useful for a TBC is formed.
  • Such a zig-zag microstructure has not heretofore been disclosed for use in producing TBC coating systems.
  • Robbie, et al. disclosed a technique for forming "sculpted" films having helical, square helical or zig-zag type shapes, but the stability of such structures, the processes by which they are formed, and the uses proposed for such structures are far different than those of the present invention. See Robbie, et al., "Sculptured Thin Films and Glancing Angle Deposition: Growth Mechanics and Applications," J. Vac. Sci.
  • the Robbie, et al. films are thin films of 60 nm to 1 ⁇ m which are extremely delicate, and therefore require the formation of a planar, dense cap on top of the film.
  • Such films clearly are too fragile for use as TBCs, which are typically in the lO ⁇ m to 150 ⁇ m thickness range (and preferably are from about l ⁇ m to about 150 ⁇ m thick), require a high degree of structural stability, and require a low thermal conductivity to which the use of a dense cap structure would be antithetical.
  • the sculpted films formed by Robbie, et al. are not identified as having special structural or thermal properties. Instead, Robbie, et al.
  • the method of the present invention may include depositing a source material directly on a substrate, or depositing the source material as a top layer adhering to a bond coat or other layer adhering to the substrate.
  • the step of providing a source material comprises providing a substrate having a bond coat or other layer thereon, and the steps of depositing the source material onto the substrate comprise depositing the source material onto the bond coat or other layer.
  • the top layer of deposited source material has a microstructure comprising at least one zig-zag segment, wherein the top and bond coats act together as a thermal and oxidation protection to the substrate.
  • the substrate may be any material on which a TBC would be useful, including components such as a turbine blade, combustor, augmentor or other engine component.
  • the source material may be any material that is useful for forming a TBC on a substrate, including materials such as ZrO 2 , or an oxide-stabilized zirconia such as yttria stabilized zirconia ("YSZ”), ceria stabilized zirconia or magnesia stabilized zirconia.
  • YSZ yttria stabilized zirconia
  • ceria stabilized zirconia or magnesia stabilized zirconia The ability to manipulate thermal conductivity may enable many materials not presently used to form TBC layers to be used for TBC applications in the future.
  • the resistance of a coating to strain may be improved by increasing the porosity or segmentation of the layer.
  • the layer will have a columnar microstructure.
  • the deposition step of the method of the present invention preferably is performed using a deposition system capable of forming a coating having increased porosity or segmentation, or most preferably, a columnar microstructure. In one embodiment of the method, this is achieved using a physical vapor deposition technique, although other techniques capable of forming such microstructures may also be used to similar advantage.
  • the step of changing the angle of incidence involves altering the direction of source material deposition flow relative to the substrate, and may comprise using a substrate manipulation device or a flow manipulation device.
  • the substrate or flow manipulation device may comprise manual means, or an electronic motor, electric/magnetic fields and gas dynamic deflection, or other mechanized means. Where mechanized means are used, such means preferably are computer controlled. Although such a device may be employed for moving the substrate about the substrate's lateral axis, the substrate preferably is held fixed relative to its normal axis during deposition in order to form a more stable microstructure.
  • the steps of depositing the source material onto the substrate for a period of time T, and depositing the source material onto the substrate for a period of time T 2 preferably are performed using approximately the same deposition rate, and also may be performed using T, approximately equal to T 2 .
  • the deposition rate may be anywhere from about 0.1 to about 100 ⁇ rn/min, and is preferably about 3 ⁇ m min or more.
  • Additional changes to the angle of incidence may be made after deposition at angles of incidence ⁇ , and ⁇ 2 .
  • the angle of incidence may be changed to ⁇ 3 and the source material may be deposited onto the substrate for a period of time T 3 .
  • the angle of incidence may be changed to ⁇ 4 , etc., and the source material may be deposited onto the substrate for period of time T 4 , etc.
  • ⁇ 4 1 , etc. are less than about 70 ° , and preferably are in the range of about 45° to about 60°. Additional time periods and respective angles of incidence may also be used.
  • the deposition step may also include forming a TBC having a columnar microstructure in which columns are generally spaced apart from one another, such that the intercolumnar spaces decrease with the thickness of the coating, Le. the space between two columns is less at the top surface of the layer than at the bottom surface.
  • the spaces between the columns decrease to zero or near-zero at the top surface of the TBC to reduce the transport of corrosive materials to the underlying materials.
  • the method of the present invention for forming TBCs may comprise providing an electron beam-directed vapor deposition ("EB-DVD") system having a deposition chamber, the chamber having coupled thereto a carrier gas stream generating means, an electron beam generating means, a substrate and an evaporant source material.
  • the method may further include providing an incidence angle control mechanism capable of altering the angle of incidence of the evaporant source material on the substrate during deposition, and impinging the evaporant source material with the electron beam to generate an evaporant.
  • the evaporant is entrained in the carrier gas stream.
  • An incidence angle control mechanism of the type previously described is used to form an angle of incidence ⁇ j between the substrate and the carrier gas stream, and the evaporant is deposited onto the substrate for a period of time T,.
  • the incidence angle control mechanism is then used to form an angle of incidence ⁇ 2 between the substrate and the carrier gas stream, and the evaporant is deposited onto the substrate at the angle of incidence ⁇ 2 for a period of time T 2 .
  • the present invention is further drawn to an apparatus for producing TBCs, the apparatus comprising a deposition chamber having coupled thereto a carrier gas stream generating means, an electron beam generating means, a substrate and an evaporant source material.
  • the apparatus further has an incidence angle control mechanism which is coupled to the deposition chamber and capable of altering the angle of incidence of a flow of the evaporant source material on the substrate during deposition, such that coatings having the zig-zag microstructures of the present invention may be formed.
  • the electron beam generating means of the apparatus comprises an electron beam gun coupled to the deposition chamber, the electron beam gun being capable of providing an electron beam in the deposition chamber when the deposition chamber is maintained at low downstream operating pressures, j ⁇ e., ranging from about 0.001 Torr or less to about 10 Torr or more.
  • the carrier gas generating means is capable of entraining the source material and directing the source material to the substrate after the electron beam has impinged upon and vaporized the source material.
  • the use of a carrier gas makes possible the deposition of source material at a high rate and with a high MUE and locally oblique angles of atom/molecule impact with the substrate surface.
  • the velocity and flux of the gas atoms entering the deposition chamber, the nozzle parameters and/or the operating pressures may be varied significantly, resulting a broad margin of control over the properties of the deposited layer.
  • the evaporant source material preferably is disposed in a water-cooled crucible.
  • the evaporant source material may be disposed inside the carrier gas generating means, which may be a nozzle surrounding the crucible or other evaporant source material holding device.
  • the carrier gas may be any inert gas, such as He or a mixture of He and one or more gases selected from O 2 , N 2 , hydrocarbons (e ⁇ g. , methane and acetylene), silanes, and other non-He inert gases.
  • the present invention is further directed to a TBC coating system having exceptional thermal and structural properties for protecting a substrate subjected to high temperatures, the coating system including a bond coat adhering to a substrate, and a top layer adhering to the bond coat.
  • the top layer has a microstructure comprising at least one zig-zag segment, wherein the coating system acts as a TBC providing thermal and oxidation protection to the substrate.
  • the TBC coating system of the present invention may be formed according to a process comprising the steps of providing a substrate, providing a source material to be deposited onto the substrate, depositing the source material onto the substrate for a period of time T, and at an angle of incidence ⁇ l5
  • the angle of incidence is changed to ⁇ 2 after time period T,
  • FIG. la is a schematic representation of a typical microstructure in a layer formed using a prior art PS system
  • FIG. lb is an enlarged view of the area circumscribed by line lb- lb in the schematic representation of FIG. la;
  • FIG. 2a is a schematic representation of a typical microstructure in a layer formed using a prior art EB-PVD system
  • FIG. 2b is an enlarged view of the area circumscribed by line 2b-2b in the schematic representation of FIG. 2a;
  • FIG. 3 is a schematic illustration showing a first angle of incidence ⁇ , between the substrate and the flow of source material
  • FIG. 4a is a schematic representation of a preferred embodiment of the zig-zag microstructure of the present invention formed using a preferred embodiment of the method of the present invention
  • FIG. 4b is an enlarged view of the area circumscribed by line 4b-4b in the schematic representation of FIG. 4a;
  • FIG. 5 is a schematic illustration of an EB-DVD system incorporating the present invention for forming a zig-zag microstructure
  • FIG. 8 is a SEM micrograph (800x) showing a zig-zag TBC layer formed as described in Example 1 ;
  • FIG. 9 is a SEM micrograph (85 Ox) showing a zig-zag TBC layer formed as described in Example 2
  • FIG. 10 is a SEM micrograph (850x) showing a zig-zag TBC layer formed as described in Example 3;
  • FIG. 11 is a SEM micrograph (lOOOx) showing a zig-zag TBC layer formed as described in Example 4.
  • FIG. 12 is a SEM micrograph (850x) showing a zig-zag TBC layer formed as described in Example 5.
  • One embodiment of the method of the present invention comprises using a conventional deposition system capable of forming a coating having a columnar microstructure, in connection with a mechanism capable of altering the angle of incidence ⁇ of a flow of source material on a substrate such as a turbine or diesel engine component.
  • the angle of incidence ⁇ is measured, as shown in Figure 3, as the angle between the normal to the substrate surface and the direction of the flow of source material toward the substrate surface during deposition.
  • a change in the angle of incidence may be accomplished using an incidence angle control mechanism such as a flow manipulation device capable of changing the direction of flow of the material being deposited, or, alternatively, a substrate manipulation device capable of moving the substrate.
  • a flow manipulation device may comprise a flexible jet nozzle made from a flexible tube which is movable by means of a motor or by electric/magnetic fields and gas dynamic deflection.
  • a substrate or flow manipulation device may include a computer-controlled, electronic servo-controlled motor or any other type or make of motor capable of rotating the substrate about its lateral axis (e.g., extending out of the page in Figure 3), or altering the direction of flow of evaporant. Both the flow and substrate manipulation devices may be operated manually or automatically.
  • Deposition at angle of incidence ⁇ 2 typically results in columns growing at an angle ⁇ 2 ', where
  • the values of T, and T 2 are determined by the deposition rate and the desired length of a zig-zag segment.
  • Deposition rates may vary from about 0.1 to about 100 ⁇ m/min, and typically are from about 5 to about 10 ⁇ m/min.
  • the process is stopped once the desired thickness is achieved. For typical TBCs, the desired thickness will range from about 50 ⁇ m to 500 ⁇ m.
  • N normal axis N (shown in Figure 3) during deposition in order to achieve columnar microstructures with desirable spallation resistance.
  • a zig-zag microstructure of the type schematically illustrated in Figures 4a and 4b may be produced. It is preferable that several additional deposition periods (T 3 , T 4 , T 5 , etc.) are used, along with additional respective angles of incidence ( ⁇ 3 , ⁇ 4 , ⁇ 5 , etc.).
  • first and second deposition periods T, and T 2 are utilized, using the same deposition rate and with T, approximately equal to T 2 and ⁇ 2 approximately equal to - ⁇ district and the length of columnar sub-segment S, therefore approximately equal to that of columnar sub-segment S 2 , such that a zig-zag microstructure similar to that schematically illustrated in Figures 4a and 4b is formed.
  • Such a morphology has been shown to effectively reduce the thermal conductivity of the coating by altering the porosity and the grain boundary orientation, while retaining the columnar structure that is necessary for ideal spallation resistance.
  • the length L of the zig-zag segments produced (as shown in Figure 4a), as well as the lengths of the columnar sub-segments S, S 2 , etc. (as shown in Figure 4b), may be controlled by varying the deposition rate and/or deposition period.
  • TBCs having the most preferable thermal and structural properties are formed using angles of incidence
  • zig-zag columnar microstructures may be produced by varying the pressures, flow parameters and/or other variables such that the intercolumnar spacing of the microstructure decreases from the bottom to the top of the TBC formed.
  • the functionally grade structure that is created by this approach can be used to prevent corrosive contaminants from dirty fuels or other substances coming into contact with the TBC coating system from penetrating into the usually porous TBC and damaging the underlying materials. Protecting the TBC coating system from such damage is important, since contamination damage may result in premature spalling or a decrease of the system's thermal properties.
  • the intercolumnar spacing is reduced to zero or near-zero at the top surface of the zig-zag layer in order to provide maximum protection to the TBC. It is believed that this will substantially enhance the durability and useful life span of TBCs produced in accordance with the present invention.
  • the TBC production method and apparatus of the present invention may be used to form a top layer directly on a substrate material, or on a bond coat or other material.
  • a bond coat any material known in the art to be useful for TBC applications may be employed, such as a material which is oxidation-resistant at the intended use temperature.
  • any conventional TBC or other coating deposition system, and any source material, capable of forming a columnar microstructure and possessing sufficiently low thermal conductivity for use in thermally protecting a substrate may be used for the present invention.
  • the deposition system used may be any form of physical vapor deposition ("PVD") system, and the source material may comprise a single material or multiple materials, such as ZrO 2 , YSZ, ceria-stabilized zirconia, magnesia-stabilized zirconia or other oxide-stabilized zirconia or other materials.
  • the source material also may be provided in any form, including, for example, a cooled wire, or a water cooled copper crucible feed system.
  • any incidence angle control mechanism may be used, provided that it is capable of altering the incidence angle of the substrate relative to the flow of material being deposited.
  • an EB-DVD system is employed, such as disclosed in U.S. Patent No. 5,534,314 to Wadley, et al, which is incorporated herein by reference in its entirety. Such a system may be used to form a TBC or other coating having a columnar microstructure.
  • an EB- DVD system includes a substrate 10 disposed in a deposition chamber 12. Substrate 10 may be fixed in position such that it is partially or fully disposed within deposition chamber 12, and may be configured to be movable further within or without deposition chamber 12.
  • deposition chamber 12 couples to deposition chamber 12 to coupled to deposition chamber 12 are an electron beam gun 14 or other electron beam generating means, a gas jet 16 or other carrier gas stream generating means, and an evaporant source material 18.
  • deposition chamber 12 typically has an operating pressure of from about 0.001 Torr to about 10 Torr, most preferably about 0.1 Torr to about 1 Torr. However, the operating pressure may be less than about 0.001 Torr or greater than about 10 Torr.
  • the evaporant source material in this embodiment is YSZ (3-11 wt% Yttria).
  • Electron beam gun 14 operates at a power of about 1.5 KW, and is capable of depositing atoms at enhanced, extremely low energy ideal for the creation of a finely porous microstructure. Such low energies preferably are in the range of about 0.04 eV to about 0.08 eV.
  • Electron beam gun 14 has a high accelerating voltage (greater than about 30 KV) to ensure penetration of the electron beam at high gas pressures.
  • Gas jet 16 operates at a pressure of about 0.1 to about 10 Torr.
  • the carrier gas must be a gas, or combination of gases, which allows penetration of the electron beam from the electron beam gun to the source material.
  • the gas is He or a mixture of He and one or more gases selected from O 2 , N 2 , hydrocarbons (e.g., methane and acetylene), silanes, and other non-He inert gases.
  • evaporant source material 18 is impinged with electron beam 13 from electron beam gun 14 to generate a vaporized evaporant or vapor flux, which is entrained in the carrier gas stream 20 generated by gas jet
  • Carrier gas stream 20 may be used to focus the vapor flux toward substrate 10 in order to coat substrate 10 with evaporant source material 18.
  • the step of impinging evaporant source material 18 with electron beam 13 may be performed if desired inside gas jet 16 or other carrier gas generating means.
  • carrier gas stream 20 could flow through a nozzle (not shown) surrounding evaporant source material 18.
  • an incidence angle control mechanism comprising a substrate manipulation device 22 is used to rotate substrate 10 and vary the angle of incidence of the flow on substrate 10.
  • Substrate manipulation device 22 preferably includes a vacuum rated motor (not shown).
  • the motor used in the present embodiment is model no. U21-RN, manufactured by Empire Magnetics, Inc of Rohnert Park, California.
  • the gas jet acts to collimate the vapor flux, effectively focusing the vapor into a region comparable (or less) than the size of the substrate, vastly improving the MUE of the deposition process.
  • the collimated flux when combined with a substrate inclined with respect to the jet flow at an angle of incidence less than about 70°, and preferably from about 45° to about 60°, allows zig-zag columns to grow with a deposition rate comparable to current, commercially employed TBC deposition techniques, making possible the achievement of exceptional thermal performance without sacrificing structural performance or adding cost to the product.
  • Significant advantages are realized by using an EB-DVD system in combination with a substrate or flow manipulation device to obtain the zig-zag microstructures of the present invention.
  • EB-DVD systems operate in extremely low vacuum environments, permitting the use of relatively low cost pumps and making possible the deposition of materials much more rapidly than is currently feasible by either traditional e-beam evaporation systems or other low vacuum vapor deposition systems.
  • the carrier gas stream of an EB-DVD system permits the focusing of a high percentage of evaporant source material onto the substrate (in the range of about 50% to 95% or more), as opposed to the low MUE (in the range of about 1% to 10%) achieved by typical EB-PVD systems.
  • the substantially improved MUE possible with EB-DVD systems results in deposition rates in the range of about 5 ⁇ m/min to about 50 ⁇ m/min or more, which is a significant improvement over the 5 ⁇ m/min to 15 ⁇ m/min rates achievable using conventional PVD systems.
  • EB-DVD systems allow such systems to be brought to a suitable pressure in less than 5 minutes, in contrast to the hours-long pump-down times required by prior art systems. This makes possible the changing of source, substrate, or other system components during maintenance or system reconfiguration shutdowns.
  • EB-DVD systems advantageously are also more compact than other systems, because they are capable of directed deposition on any desired substrate in any position.
  • EB-DVD systems permit the coating of single turbine blades and other components sequentially, without a need to employ complicated multi-substrate manipulation systems such as those used by prior systems in order to capture as much evaporant as possible.
  • Example 1 Three TBC samples were prepared for comparison using an EB-DVD system operating with similar processing parameters, but only one using the zig-zag method of the present invention.
  • YSZ (7 wt% Yttria) was deposited on an IN 100 substrate with a NiAl bond coat. The substrate was maintained at about 1000°C during deposition.
  • a chamber pressure of about 0.35 Torr and an upstream gas pressure of about 2.36 Torr were employed.
  • the gas used was approximately 98.8% He and 1.2% O 2 , flowing at about 8.1 standard liters/minute and a speed of about Mach 1.75. Evaporation was begun using an electron beam power of about 1.5 KW.
  • the power was increased in approximately 0.3 KW increments every 2.5 minutes for a total deposition time of about 10 minutes, ending with a maximum power of about 2.4 KW. This was done in an effort to compensate for the changing source material shape during deposition and maintain a generally constant source material evaporation rate.
  • the thermal conductivity was measured using a steady-state measurement technique designed to accurately determine the thermal properties of thin (about 140 ⁇ m or less) coatings with unique microstructures.
  • the approach involves using an infrared microscope to measure differences on small, millimeter sized specimens. During measurement, heat is applied to the outer surface of the coating using a 10 W continuous-beam laser. The infrared microscope is then used to measure the temperature at different locations along the cross-section of the coating. The thermal conductivity of the coating is determined using the Fourier conduction equation
  • a second sample was prepared by depositing YSZ (7 wt% Yttria) on an IN 100 substrate with a NiAl bond coat.
  • the substrate was maintained at about 1000°C.
  • a chamber pressure of about 0.65 Torr and an upstream gas pressure of about about 3.90 Ton- were employed.
  • the gas used was approximately 98.7% He and 1.3% O 2 , flowing at about 15.2 standard liters/minute and a speed of about Mach 1.75.
  • Evaporation was begun using an electron beam power of about 1.5 KW.
  • the power was increased in approximately 0.3 KW increments every 5.0 minutes for a total deposition time of about 20 minutes, ending with a maximum power of about 2.4 KW.
  • a third sample was made using the same materials and parameters as the second sample, but with a chamber pressure of about 0.65 Torr and an upstream gas pressure of about 3.86 Torr.
  • the angle of incidence was changed using a substrate manipulation device comprising a computer-controlled electronic motor to rotate the substrate about its lateral axis.
  • the flow of evaporant was not interrupted while the angle of incidence was changed.
  • First and second deposition periods T, and T 2 were repeated using first and second angles of incidence 0, and ⁇ 2 , respectively, several times.
  • the result was a layer having the columnar zig-zag microstructure shown in Figure 8, and a thermal conductivity of about 1.0
  • Example 2 A sample was prepared by depositing YSZ (7 wt% Yttria) on an IN 100 substrate with a NiAl bond coat. The substrate was maintained at about 1030°C. A chamber pressure of about 0.19 Torr and an upstream gas pressure of about 1.91 Torr were employed.
  • the gas used was approximately 96.6% He and 3.4% O 2 , flowing at about 7.25 standard liters/minute.
  • An average electron beam power of about 1.29 KW was used, with the power being increased during deposition in an effort to compensate for the changing source material shape and maintain a generally constant source material evaporation rate.
  • the angle of incidence was changed using a substrate manipulation device comprising a computer-controlled electronic motor to rotate the substrate about its lateral axis.
  • First and second deposition periods T, and T 2 were repeated using first and second angles of incidence ⁇ , and ⁇ 2 , respectively, several times. The result was a layer having the columnar zig-zag microstructure shown in Figure 11, and a thermal conductivity less than that achieved in the samples of Examples 2 and 3.
  • First and second deposition periods T, and T 2 were repeated using first and second angles of incidence ⁇ , and ⁇ 2 , respectively, several times.
  • the result was a layer having the columnar zig-zag microstructure shown in Figure 12, and a thermal conductivity less than that achieved in the samples of Examples 2, 3 and 4.
  • TBCs formed using the parameters set forth in this example would be expected to be highly compliant and resistant to sintering in high- temperature applications. This should also be true of the zig-zag samples of Examples 1 through 4.

Abstract

Cette invention a trait à un procédé ainsi qu'au dispositif correspondant permettant de produire un système d'enduisage constituant une barrière thermique sur un substrat, comprenant une couche de cohésion adhérant audit substrat ainsi qu'une couche sommitale, adhérant à la couche de cohésion et possédant une microstructure comportant au moins un segment en zigzag. Le procédé consiste à placer le substrat (10) dans une enceinte à formation de dépôt (12), à bombarder une source d'agent évaporant (18) au moyen d'un faisceau électronique (13) émanant d'un canon à électrons (14) afin de former un agent évaporant, à introduire cet évaporant dans un gaz porteur (20) pour créer un flux d'évaporant et à déposer cet évaporant sur le substrat pour constituer la couche sommitale. Pendant le processus de dépôt, un dispositif (22) fait tourner le substrat de manière à modifier l'angle d'incidence du flux relativement au substrat.
PCT/US1999/013450 1998-06-16 1999-06-15 Dispositif et procede de production d'enduits constituant une barriere thermique WO1999065626A1 (fr)

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US8940198P 1998-06-16 1998-06-16
US60/089,401 1998-06-16
US12809599P 1999-04-07 1999-04-07
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Cited By (9)

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Publication number Priority date Publication date Assignee Title
US6183884B1 (en) 1998-01-13 2001-02-06 Rolls-Royce Plc Metallic article having a thermal barrier coating and a method of application thereof
WO2004048632A2 (fr) * 2002-11-21 2004-06-10 University Of Virginia Patent Foundation Couche d'ancrage pour systeme de revetement de barriere thermique et procede connexe
WO2005047202A2 (fr) * 2003-07-29 2005-05-26 University Of Virginia Patent Foundation Procede d'application d'un revetement de barriere thermique et structure obtenue
EP1640473A1 (fr) * 2004-09-14 2006-03-29 General Electric Company Revêtement de barrière thermique ayant une structure granuliare modulée et procédé correspondant
EP2236643A2 (fr) 2009-03-31 2010-10-06 United Technologies Corporation Appareil de dépôt en phase vapeur par faisceau d'électrons et procédé de revêtement
US9640369B2 (en) 2009-02-24 2017-05-02 University Of Virginia Patent Foundation Coaxial hollow cathode plasma assisted directed vapor deposition and related method thereof
US9745736B2 (en) 2013-08-27 2017-08-29 University Of Virginia Patent Foundation Three-dimensional space frames assembled from component pieces and methods for making the same
US10184759B2 (en) 2015-11-17 2019-01-22 University Of Virgina Patent Foundation Lightweight ballistic resistant anti-intrusion systems and related methods thereof
US10378861B2 (en) 2014-09-04 2019-08-13 University Of Virginia Patent Foundation Impulse mitigation systems for media impacts and related methods thereof

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US4303694A (en) * 1979-05-04 1981-12-01 Daniel Bois Method and device of deposition through vacuum evaporation making use _of a modulated electron beam and a screen
US4676994A (en) * 1983-06-15 1987-06-30 The Boc Group, Inc. Adherent ceramic coatings
US5534314A (en) * 1994-08-31 1996-07-09 University Of Virginia Patent Foundation Directed vapor deposition of electron beam evaporant

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Publication number Priority date Publication date Assignee Title
US4303694A (en) * 1979-05-04 1981-12-01 Daniel Bois Method and device of deposition through vacuum evaporation making use _of a modulated electron beam and a screen
US4676994A (en) * 1983-06-15 1987-06-30 The Boc Group, Inc. Adherent ceramic coatings
US5534314A (en) * 1994-08-31 1996-07-09 University Of Virginia Patent Foundation Directed vapor deposition of electron beam evaporant

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6183884B1 (en) 1998-01-13 2001-02-06 Rolls-Royce Plc Metallic article having a thermal barrier coating and a method of application thereof
WO2004048632A2 (fr) * 2002-11-21 2004-06-10 University Of Virginia Patent Foundation Couche d'ancrage pour systeme de revetement de barriere thermique et procede connexe
WO2004048632A3 (fr) * 2002-11-21 2004-07-15 Univ Virginia Couche d'ancrage pour systeme de revetement de barriere thermique et procede connexe
WO2005047202A2 (fr) * 2003-07-29 2005-05-26 University Of Virginia Patent Foundation Procede d'application d'un revetement de barriere thermique et structure obtenue
WO2005047202A3 (fr) * 2003-07-29 2005-08-25 Univ Virginia Procede d'application d'un revetement de barriere thermique et structure obtenue
US7318955B2 (en) 2004-09-14 2008-01-15 General Electric Company Thermal barrier coating with modulated grain structure and method therefor
EP1640473A1 (fr) * 2004-09-14 2006-03-29 General Electric Company Revêtement de barrière thermique ayant une structure granuliare modulée et procédé correspondant
US9640369B2 (en) 2009-02-24 2017-05-02 University Of Virginia Patent Foundation Coaxial hollow cathode plasma assisted directed vapor deposition and related method thereof
EP2236643A2 (fr) 2009-03-31 2010-10-06 United Technologies Corporation Appareil de dépôt en phase vapeur par faisceau d'électrons et procédé de revêtement
EP2236643A3 (fr) * 2009-03-31 2011-01-19 United Technologies Corporation Appareil de dépôt en phase vapeur par faisceau d'électrons et procédé de revêtement
US8419857B2 (en) 2009-03-31 2013-04-16 United Technologies Corporation Electron beam vapor deposition apparatus and method of coating
US9745736B2 (en) 2013-08-27 2017-08-29 University Of Virginia Patent Foundation Three-dimensional space frames assembled from component pieces and methods for making the same
US10378861B2 (en) 2014-09-04 2019-08-13 University Of Virginia Patent Foundation Impulse mitigation systems for media impacts and related methods thereof
US10184759B2 (en) 2015-11-17 2019-01-22 University Of Virgina Patent Foundation Lightweight ballistic resistant anti-intrusion systems and related methods thereof

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