IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`
`
`Eaton et al.
`In re Patent of:
`7,060,360 Attorney Docket No.: 43498-0002IP1
`U.S. Patent No.:
`June 13, 2006
`
`Issue Date:
`Appl. Serial No.: 10/443,342
`
`Filing Date:
`May 22, 2003
`
`Title:
`BOND COAT FOR SILICON BASED SUBSTRATES
`
`
`
`
`SUPPLEMENTAL DECLARATION OF DR. DAVID R. CLARKE
`
`I, David R. Clarke, declare as follows:
`
`1.
`
`This declaration supplements the declaration entitled “Declaration of
`
`Dr. David R. Clarke” dated October 6, 2016 (hereinafter “Original Declaration”).
`
`The statements made and opinions rendered therein can be assumed to be
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`incorporated into this supplemental declaration, except as may be explicitly noted
`
`otherwise herein.
`
` Materials Considered
`In addition to the materials I reviewed in preparation of my Original
`2.
`
`Declaration—which were noted in paragraphs 8 through 10—I have reviewed the
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`following list of materials in preparation of this declaration:
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`• Institution Decision in IPR2016-01289 entered on December 27, 2016
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`(Paper 7)
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`Page 1 of 26
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`UTC 2013
`General Electric v. United Technologies
`IPR2016-01289
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`

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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`• M.E. Westwood et al., Oxidation protection for carbon fibre composites, 31
`
`Journal of Materials Science. 1389-1397 (1996). (UTC-2016)
`
`• M. Ohring, ENGINEERING MATERIALS SCIENCE (1995). (UTC-2017)
`
`• L.H. Van Vlack, ELEMENTS OF MATERIALS SCIENCE AND ENGINEERING
`
`(1989). (UTC-2018)
`
`• K.N. Lee, Key Durability Issues With Mullite-Based Environmental Barrier
`
`Coatings for Si-Based Ceramics, 122 Transactions of the ASME. 632-636
`
`(2000). (UTC-2020)
`
`• N.S. Jacobson et al., Oxidation and corrosion of ceramics and ceramic
`
`matrix composites, 5 Current Opinion in Solid State and Materials Science.
`
`301-309 (2001). (UTC-2021)
`
`• K.N. Lee, Current status of environmental barrier coatings for Si-Based
`
`ceramics, 133-134 Surface and Coatings Technology. 1-7 (2000). (UTC-
`
`2022)
`
`• S.V. Raj, Comparison of the Thermal Expansion Behavior of Several
`
`Intermetallic Silicide Alloys Between 293 and 1523 K, 24 Journal of
`
`Materials Engineering and Performance, 1199-1205 (2015). (UTC-2023)
`
`• D. Zhu et al., Thermal Conductivity of Ceramic Thermal Barrier and
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`Environmental Barrier Coating Materials, NASA/TM–2001-211122 (2001).
`
`(UTC-2024)
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`Page 2 of 26
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`• R. Siegel and C.M. Spuckler, Analysis of thermal radiation effects on
`
`temperatures in turbine engine thermal barrier coatings, A245 Materials
`
`Science and Engineering, 150-159 (1998). (UTC-2025)
`
`• M. Peters et al., Design and Properties of Thermal Barrier Coatings for
`
`Advanced Turbine Engines, 28 Materialwissenschaft und Werkstofftechnik.
`
`357-362 (1997). (UTC-2026)
`
`• R.H. Doremus, Viscosity of silica, 92 Journal of Applied Physics, 7619-7629
`
`(2002). (UTC-2027)
`
`3.
`
`I have also considered all other materials cited herein.
`
` Applicable Legal Standards
`In this supplemental declaration, I am applying the same standards
`4.
`
`and legal principles that I applied when drafting my Original Declaration, which
`
`were outlined in paragraphs 17 through 32 of that document.
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` Design of Multilayer Coatings
`As I noted in paragraph 34 of my Original Declaration, a coating is a
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`5.
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`thin layer of material that is formed or deposited on the surface of a substrate.
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`Often, a coating is applied to a substrate to create a composite material that has
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`properties that are not present in the substrate alone: “Coatings enable the
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`attributes of two or more materials [e.g., the coating and the substrate] to be
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`combined to form a composite having characteristics not readily available in a
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`monolithic material.” UTC-2002, p. xii.
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`6.
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`A coating including multiple layers of material is referred to as a
`
`multilayer coating. Multilayer coatings are often formed on a substrate to obtain a
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`composite material having properties or a combination of properties or functions
`
`not available from a single coating material.
`
` Factors in Designing a Multilayer Coating
`In selecting materials for a multilayer coating, one must take into
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`7.
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`account a number of factors, including the properties of the individual constituent
`
`layers as well as interactions that will occur between layers in the multilayer
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`coating and between the coating and the substrate. Such factors include, but are
`
`not limited to, compatibility of the coefficients of thermal expansion, chemical
`
`compatibility, environmental stability, elastic moduli, and the evolution of
`
`interfaces in the coating or between the coating and the substrate. See GE-1011, p.
`
`1; UTC-2002, p. 11; UTC-2021, p. 305, UTC-2022, p. 1, UTC-2002, p. 11, GE-
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`1011, p. 1. Consideration of these factors is particularly important when designing
`
`a multilayer coating for use under harsh environmental conditions such as high
`
`temperatures, high velocity gas flows, or repeated thermal cycling to high
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`temperatures. Absent knowledge of previously developed evidence of these
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`factors for the actual materials being considered, a POSITA would not have
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`perceived a reasonable likelihood of success in combining layers into a multilayer
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`system, capable of withstanding high temperature service in a gas turbine, without
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`undertaking expensive and time-consuming experimentation.
`
`8.
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`The thermal expansion coefficient of a material is a quantitative
`
`measure of the amount by which the material will expand or contract in response to
`
`a change in temperature. See UTC-2017, p. 61. Selection of materials for a
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`multilayer coating that have compatible thermal expansion coefficients is crucial
`
`for the stability of the coating. If layers in a multilayer coating have different
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`thermal expansion coefficients, those layers will expand or contract by different
`
`amounts when the multilayer coating is heated or cooled. These differences in
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`expansion or contraction can cause stresses to develop in the multilayer coating. In
`
`some cases, thermal stresses can result in structural failures, such as cracking in the
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`coating or at an interface between the coating and the substrate leading to
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`delamination of the coating from the substrate. See UTC-2006, p. 179; UTC-2021,
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`p. 305; UTC-2022, p. 1.
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`9.
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`Chemical compatibility of materials in a multilayer coating is an
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`indication of whether the materials can coexist in the coating without resulting in
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`chemical reactions between the materials. Layers of a multilayer coating should be
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`chemically compatible, and the coating should be chemically compatible with the
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`substrate, “to avoid detrimental chemical reactions.” UTC-2021, p. 35, UTC-2022,
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`p. 1; see also UTC-2002, p. 11.
`
`10. Environmental properties of a coating or of layers thereof include
`
`durability against corrosion and / or oxidation and oxygen permeability. See UTC-
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`2021, p. 305, UTC-2022, p. 1. To design a durable coating, materials can be
`
`selected that have good resistance to corrosion by water vapor or other corrosive
`
`species and to oxidation and that have low oxygen permeability to limit transport
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`of oxygen through the coating and to the substrate. See Id.
`
`11. The elastic modulus of a material is a quantitative measure of the
`
`stiffness of a material and describes its’ elastic deformation in response to an
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`applied stress. See UTC-2017, p. 60; UTC-2018, p. 252. The elastic modulus of
`
`each layer of a multilayer coating must be considered in addition to its thermal
`
`expansion in order to understand how the coating as a whole will deform under
`
`stress. In some cases, layers with low elastic moduli can be selected “to enhance
`
`the compliancy of the coating under stress.” UTC-2021, p. 305.
`
`12. The evolution of an interface between two materials describes how the
`
`interface changes over time. An interface between two layers in a multilayer
`
`coating can evolve due to diffusion of atoms or molecules from one layer to
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`another, changing the sharpness of the interface and the chemical composition of
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`both of the layers in the vicinity of the interface. These changes can alter the
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`physical properties of the layers, such as the thermal expansion coefficients of the
`
`layers. The changes can also alter the fracture energy of the interface, which in turn
`
`can result in structural degradation of the multilayer coating. An understanding of
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`the expected evolution of each interface of a multilayer coating is crucial to ensure
`
`that the evolution does not adversely affect the behavior or stability of the
`
`multilayer coating.
`
`
`
`Thermal Expansion Coefficient of Terentieva’s Protective
`Coating
`13. Terentieva’s protective coating is, itself, a composite material. It
`
`includes a healing phase that “is constituted by a eutectic which is formed mainly
`
`of unbound silicon, of the mixed disilicide Ti(0.4-0.95)Mo(0.6-0.05)Si2 and of at least the
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`disilicide TiSi2.” GE-1005, 2:65-67. It also includes “a refractory phase that
`
`presents a branching microstructure forming an armature within which a healing
`
`phase is distributed.” GE-1005, 2:59-61. In addition, Terentieva’s protective
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`coating “includes a surface oxide film comprising the silica obtained by oxidizing
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`the silicon and the silicides contained in the coating.” GE-1005, 3:5-7.
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`14. The coefficient of thermal expansion of Terentieva’s protective
`
`coating must be determined based on the coefficient of thermal expansion of each
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`of the constituent phases of the protective coating: the healing phase, the refractory
`
`phase, and the surface oxide film, and their volume fractions.
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`In discussing the coefficient of thermal expansion of Terentieva’s
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`15.
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`protective coating, Dr. Glaeser states that “one of skill in the art would have known
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`that combinations of Si and MoSi2 have CTEs within the range of 2.6 and 8 ppm,”
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`and thus that “a BSAS barrier layer can be applied directly to a Mo-Si alloy layer.”
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`GE-1003, ¶ 57. However, Terentieva’s coating does not contain a MoSi2 phase.
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`More generally, Terentieva’s protective coating is not a Mo-Si alloy layer, and a
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`POSITA would not have expected the coefficient of thermal expansion of a Mo-Si
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`alloy, such as MoSi2, to have the same coefficient of thermal expansion of
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`Terentieva’s protective coating. The physical and chemical differences between a
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`simple and unspecified Mo-Si alloy and Terentieva’s more complex protective
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`coating are simply too great.
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`16.
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`In particular, the chemical composition of Terentieva’s protective
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`coating includes more than just Si and a Mo-Si alloy. Terentieva’s protective
`
`coating includes the mixed refractory disilicide Ti(0.4-0.95)Mo(0.6-0.05)Si2 in both the
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`armature-forming refractory phase and the healing phase. The presence of
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`titanium in Terentieva’s mixed refractory disilicide has the potential to cause the
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`disilicide Ti(0.4-0.95)Mo(0.6-0.05)Si2 to have a significantly different coefficient of
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`thermal expansion than the simple disilicide MoSi2 referenced by Dr. Glaeser.
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`Terentieva’s protective coating also includes the disilicide TiSi2, the thermal
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`expansion coefficient of which is unrelated to the thermal expansion coefficient of
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`MoSi2. Indeed, data from Raj shows that TiSi2 has a significantly higher thermal
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`expansion coefficient than MoSi2. UTC-2023, p. 1204. The presence of the
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`mixed refractory disilicides and the disilicide TiSi2 in Terentieva’s protective
`
`coating can cause the overall coefficient of thermal expansion of the protective
`
`coating to be significantly different than the thermal expansion coefficient of a
`
`material including only Si and MoSi2. Furthermore, as noted above, the overall
`
`coefficient of thermal expansion will also depend on the volume fractions of each
`
`of the phases in the coating. Dr. Glaeser’s reference to the thermal expansion
`
`coefficients of combinations of Si and MoSi2 is thus insufficient to predict the
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`thermal expansion coefficient of Terentieva’s protective coating.
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`17.
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`In addition, the physical structure of Terentieva’s protective coating is
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`far more complex than a simple Mo-Si alloy layer. Terentieva’s protective coating
`
`includes “a branching microstructure forming an armature within which a healing
`
`phase is distributed.” GE-1005, 2:59-61. The branched microstructure of
`
`Terentieva’s protective coating can affect the thermal expansion coefficient of the
`
`protective coating, a factor for which Dr. Glaeser fails to account.
`
`18. To determine the coefficient of thermal expansion of Terentieva’s
`
`protective coating, a POSITA would have to take into consideration the chemical
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`composition of the armature-forming refractory phase, the TiSi2 and of the healing
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`phase accounting for the volume fraction of each of the individual phases, their
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`individual thermal expansion coefficients as well as their microstructural shapes,
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`such as the branching microstructure of the armature. Making such a
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`determination experimentally, and any changes with high temperature exposure,
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`would require extensive, and expensive, physical testing at high temperatures.
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`Because of the large number of variables, including the possible variations in
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`fractions of each of the three phases, calculating the overall coefficient of thermal
`
`expansion would not have been possible at the time of the patent. Dr. Glaeser’s
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`analogy between the coefficient of thermal expansion of combinations of Si and
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`MoSi2 and the coefficient of thermal expansion of Terentieva’s protective coating
`
`is an oversimplification that has no basis, and thus would not be expected to give
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`an accurate estimate of the coefficient of thermal expansion of Terentieva’s
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`protective coating. An accurate estimate is necessary since the calculation of the
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`thermal expansion mismatch induced stresses depend on the difference between
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`thermal expansion coefficients (i.e., the mismatch) not the thermal expansion
`
`coefficient per-se.
`
` Multilayer Coatings in Harsh Environments
` Cracking and Erosion of Coatings
`19. When a coated substrate is exposed to high temperatures or to
`
`repeated thermal cycling, cracks can develop at the interface between the substrate
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`and the coating or between adjacent layers of the coating. See GE-1005, 1:39-47;
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`UTC-2006, p. 179; UTC-2020, p. 4. Cracking often occurs because of a mismatch
`
`in the coefficients of thermal expansion of the constituent layers in a multilayer
`
`coating that gives rise to internal stresses within the coating. See UTC-2016, p.
`
`1390; UTC-2020, p. 4. It can also occur as a result of thermal expansion mismatch
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`between the coating and the underlying substrate. Cracking can also occur as a
`
`result of changes to one or more layers of the coating that occur at high
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`temperatures. See UTC-2007, p. 399, 403; UTC-2008, p. 114; UTC-2021, p. 305.
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`20. The existence of cracks in a multilayer coating or between a coating
`
`and a substrate can negatively affect the performance of the coating and the
`
`substrate. For instance, the presence of cracks can degrade the strength of a
`
`coating, leading to structural failure of the coating, such as delamination of the
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`coating from the substrate. See UTC-2006, p. 179; UTC-2016, p. 1390; UTC-
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`2020, p. 632; UTC-2022, p. 1. Cracks can also provide a pathway by which
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`corrosive species, such as oxygen, water vapor, or salts, can penetrate through the
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`coating to attack the underlying substrate, thus causing oxidation or corrosion that
`
`can damage the structural integrity of the substrate. See UTC-2020, p. 632; UTC-
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`2022, p. 2, 3.
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`21. The surface of a material exposed to high temperatures and high
`
`velocity gas flows, such as a coating on an aerospace component or gas turbine,
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`can be degraded by erosion, in which the gas flowing past the surface sweeps
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`material off of the surface. This erosion process can endanger the structural
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`integrity of the material, for instance by creating pits in the material that can act as
`
`catalysts for the growth of cracks in the material. Low viscosity materials, such as
`
`healing phases (discussed below), are particularly susceptible to erosion when
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`exposed to intense gas flows. See GE-1005, 2:15-21.
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`Environmental and Thermal Barrier Layers
`
`22. Components used under harsh environmental conditions can be coated
`
`with a multilayer coating that includes an environmental barrier coating or a
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`thermal barrier coating that protects the multilayer coating and the underlying
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`component from the environment. See GE-1005, 1:34-38; GE-1006, 1:59-63;
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`UTC-2007, p. 383; UTC-2020, p. 632; UTC-2021, p. 305; UTC-2024, p. 1.
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`23. An environmental barrier coating is a layer that protects an underlying
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`substrate from environmental attack. See UTC-2020, p. 632. Environmental
`
`attacks can include oxidation of the substrate by oxygen in the environment and
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`corrosion of the substrate by corrosive species such as water vapor or salts in the
`
`environment. See UTC-2020, p. 632; UTC-2022, p. 1.
`
`24. A thermal barrier coating is a layer that protects an underlying
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`substrate from extreme temperatures by “provid[ing] a low thermal conductivity
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`barrier to heat transfer from the hot gas in the engine to the surface of the coated
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`alloy component.” UTC-2007, p. 383. In a system with a thermal barrier coating
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`disposed on a substrate in a high temperature environment, a temperature gradient
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`exists across the thickness of the thermal barrier coating such that the temperature
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`in the environment is higher than the temperature at the interface between the
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`thermal barrier coating and the substrate. The presence of a thermal barrier coating
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`can, for instance, “allow[] the turbine designer to increase the gas temperature and
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`thereby the engine efficiency, without increasing the surface temperature of the
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`alloy.” UTC-2007, p. 383.
`
`25.
`
`It is not uncommon for a protective layer to perform both functions
`
`(environments and thermal protection). For example, the environmental barrier
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`coating of Eaton ’456 “also functions as a thermal barrier layer.” GE-1006, 2:49-
`
`50. This layer is “a barium alumino-silicate and, preferably, a barium-alkaline
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`earth aluminosilicate wherein the alkaline earth metal is ideally strontium.” GE-
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`1006, 2:5-8. The thickness of the barrier layer is “ideally between about 3 to about
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`5 mils.” GE-1006, 3:50-53. The environmental barrier layer of the background of
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`the ’360 Patent has a similar composition and also functions as both an
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`environmental barrier layer and, because of its low thermal conductivity, a thermal
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`barrier layer.
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`26. The thermal conductivity of a barium-strontium alumino-silicate
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`barrier layer, deposited by plasma-spraying, has been reported to be about 2.2
`
`W/m-K in the surface temperature range of 900 to 1350oC, determined after the
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`initial stage sintering of the coating. UTC-2024, p. 11. The reduction in
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`temperature across a thermal barrier coating depends not only on the thermal
`
`conductivity of the coating material and its thickness but also on the heat flux per
`
`unit area through the coating. This, in turn, is dependent on the temperature of the
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`internal cooling of the substrate, the hot gas temperature as well as the appropriate
`
`convective heat transfer coefficients and the translucency of the coating. See UTC-
`
`2025, p. 150. Nevertheless, an estimate of the temperature drop across the
`
`environmental barrier coating of Eaton ’456 can be made based on the engine
`
`conditions considered by Peter et al. for a heat flow of 1.25 MW/m2 used in
`
`calculating temperature drops. UTC-2026, p. 359. For the environmental barrier
`
`coating of Eaton ’456 the reduction in temperature across the coating would be
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`42oC for a 3 mil coating and 71oC for a 5 mil coating, calculated based on the value
`
`of the thermal conductivity cited above. UTC-2024, p. 11.
`
` Healing Phases in Multilayer Coatings
`27. A healing phase or healing layer in a multilayer coating formed on a
`
`component can heal cracks that form in the coating or between the component and
`
`the coating as a result of exposure to high temperatures or thermal cycling. For
`
`instance, healing layers could provide crucial healing functionality for components
`
`used in harsh environments, such as in gas turbine engines for aerospace
`
`applications. A healing layer is “a layer that is capable … of stopping, filling, or
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`sealing the cracks while following the movements of the cracks, and capable of
`
`doing this without itself cracking.” GE-1005, 1:54-5. The presence of a healing
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`layer can “provide effective oxidation protection over long periods of time and
`
`under conditions of thermal cycling … [by] sealing cracks which will inevitably
`
`form during service.” UTC-2016, p. 1392. By sealing cracks that form in the
`
`coating or between the component and the coating, delamination of the coating can
`
`be prevented and the substrate can be better protected from attack by oxygen or
`
`corrosive species. As a result, the reliability of the component can be improved
`
`and the lifetime of the component extended when a healing phase can flow into
`
`and seal cracks.
`
` Glassy Oxides for Healing Phases
`28. Healing phases are often formed of glasses, such as oxides (e.g.,
`
`borate glass or silica). See GE-1005, 1:59-63; UTC-2016, p. 1392. Glassy
`
`materials are materials whose viscosity decreases with increasing temperature,
`
`meaning that they can flow more easily at high temperatures than at low
`
`temperatures. See UTC-2017, p. 416. When a coating that includes an oxide-
`
`based healing phase is exposed to high temperature, the oxide has the potential to
`
`flow into the cracks, thus filling the cracks and preventing further crack growth.
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`See GE-1005, 2:3-4; UTC-2016, p. 1392.
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`29. The viscosity of a material is a measure of the material’s resistance to
`
`flow. (Its reciprocal is sometimes referred to as the fluidity. See UTC-2018, p.
`
`580. A material with low viscosity flows easily; a material with high viscosity
`
`does not. See UTC-2017, p. 416. Water is an example of a material that has low
`
`viscosity at room temperature; maple syrup is an example of a material that has a
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`higher viscosity, about 3,000 times higher, at room temperature and tar would be
`
`an example of a material with a substantially much higher viscosity at room
`
`temperature, orders of magnitude higher still.
`
`30. The viscosity of a material is a highly temperature-dependent
`
`property. As temperature increases, the viscosity of a material rapidly decreases
`
`and the material flows more easily. Conversely, as temperature decreases, the
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`viscosity of the material rapidly increases and the material becomes much less able
`
`to flow. See UTC-2017, p. 416. This property is exemplified by tar. When tar is
`
`hot it flows easily because its viscosity is low, yet tar at room temperature barely
`
`flows at all because its viscosity rapidly increases with the reduction in
`
`temperature. When it is hot, tar can flow into gaps in a roadway, sealing its surface
`
`but once it is cold it is too viscous to flow.
`
`31. Glassy oxide materials have viscosities that decrease exponentially as
`
`the temperature increases. See UTC-2017, p. 416. An exponential dependence on
`
`temperature means that a small change in temperature results in a significant
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`U.S. Patent No. 7,060,360
`change in viscosity. Glassy materials thus are increasingly fluid and able to flow
`
`as the temperature increases. In the context of a healing phase, a glassy material
`
`can flow more easily into cracks in a coating or between a coating and a substrate
`
`at higher temperatures, enhancing its healing functionality. Conversely, the
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`viscosity of glassy materials increases rapidly as the temperature decreases, and
`
`these materials become increasingly resistant to flow. The ability of a glassy
`
`material to exhibit healing functionality is thus hindered at lower temperatures.
`
`Indeed, at low enough temperatures, typically below the softening point, a glassy
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`material becomes unable to flow, and hence would be incapable of providing any
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`healing functionality. See UTC-2017, p. 416.
`
`32. The temperature dependence of the viscosity of silica (SiO2), the
`
`oxide formed by the oxidation of silicon and silicon carbides, has been studied
`
`extensively. See UTC-2027, p. 7619. At 1300 oC (the approximate eutectic
`
`melting temperature of the healing phase of the Terentieva coating), the viscosity
`
`of silica is 1.67 x 1011 poise. UTC-2027, p. 7620. Decreasing the temperature by
`
`only 20oC (i.e., by only about 1.5%), the viscosity increases to 3.38 x 1011 poise, an
`
`increase of a factor of two (i.e., a 100% increase). See id.
`
`33. The viscosity is dependent on the composition of the glass and is
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`invariably reduced when the glass contains other elements making it more fluid.
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`Nevertheless, the viscosity values maintain an exponential dependence on the
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`inverse of temperature. See UTC-2017, p. 416.
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`Eutectic Materials as Healing Phases
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`34. Healing phases can be formed of materials that are liquid at the
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`operating temperature of a component but are otherwise solid. See GE-1005, 2:65.
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`An example of such a material is a eutectic material.
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`35. A eutectic material is a mixture of two or more phases that abruptly
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`melts at a temperature (known as the eutectic temperature) that is less than the
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`melting temperature of any of the constituent phases of the mixture. See UTC-
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`2017, 215. At temperatures higher than the eutectic temperature, a liquid is
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`formed; at temperatures lower than the eutectic temperature, the material is entirely
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`solid. This behavior contrasts that of an oxide glass, which exhibits a continuous
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`change in viscosity with temperature, as described above.
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`36.
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`In the context of a healing phase, a eutectic material would be capable
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`of exhibiting healing functionality at temperatures higher than its eutectic
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`temperature; the eutectic liquid phase can flow and would be capable of flowing
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`into cracks in a coating or between a coating and a substrate. At temperatures
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`below the eutectic temperature, the entire material is a solid and unable to flow as a
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`liquid, and thus cannot exhibit healing functionality.
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` Healing Functionality in Terentieva’s Protective Coating
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`Page 18 of 26
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`37. Terentieva’s protective coating includes a healing phase that “is
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`constituted by a eutectic which is formed mainly of unbound silicon, of the mixed
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`disilicide Ti(0.4-0.95)Mo(0.6-0.05)Si2 and of at least the disilicide TiSi2.” GE-1005,
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`2:65-67. Terentieva’s protective coating also includes “a refractory phase that
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`presents a branching microstructure forming an armature within which a healing
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`phase is distributed.” GE-1005, 2:59-61. (Here and in previous parts of this
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`declaration, I interpret the term “armature” in the old-fashioned use of the word to
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`mean a “cage” rather than the more modern use of the word as a part of an
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`electrical motor describing the winding of wires on an armature). Terentieva’s
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`protective coating “further includes a surface oxide film comprising the silica
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`obtained by oxidizing the silicon and the silicides contained in the coating.” GE-
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`1005, 3:5-7.
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`38. The role of Terentieva’s refractory phase is to prevent the healing
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`phase from “being swept away” by erosion when “exposed to intense heat flows or
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`to gas flows at very high speeds.” GE-1005, 2:44-56. In particular, Terentieva’s
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`refractory phase forms a three-dimensional armature throughout the protective
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`coating to which the healing phase can adhere. When the healing phase transforms
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`into a liquid above the eutectic high temperature, the armature holds and protects
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`the healing phase from erosion due to high velocity heat flows or gas flows. GE-
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`1005, 3:28-33. In other words, Terentieva specifically designed its protective
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`coating to include the armature formed by the refractory phase so that when the
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`healing phase exceeds the eutectic temperature it could perform its healing
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`function yet be constrained by the armature from being swept away by the high
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`velocity gases flowing through the turbine. See GE-1005, 2:48-56, 3:21-33.
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`39. Healing functionality in Terentieva’s protective coating is provided
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`both by the surface oxide film and by the eutectic that constitutes the healing
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`phase. GE-1005, 3:21-27. At high temperatures, when the temperature exceeds
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`the eutectic temperature, the eutectic of the healing phase is a liquid and thus can
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`flow into cracks in the coating or between the coating and the substrate. In
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`addition at high temperatures, the viscosity of the surface oxide could be
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`sufficiently low that the oxide can be sufficiently fluid as to flow and also heal
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`cracks that form in the protective coating.
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`40. At temperatures below the eutectic temperature, however, the healing
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`functionality of Terentieva’s protective coating is hindered or even entirely
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`eliminated. As the temperature decreases, the surface oxide film becomes
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`increasingly viscous and less able to flow into cracks. Furthermore, when the
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`temperature falls below the eutectic temperature, the eutectic of the healing phase
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`becomes solid and thus cannot exhibit any flow behavior or healing functionality.
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` Effect of a Thermal Barrier Coating on Terentieva’s Protective
`Coating
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`Page 20 of 26
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`Attorney Docket No.: 43498-0002IP1
`U.S. Patent No. 7,060,360
`41. The Petition proposes placing the environmental barrier layer of
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`Eaton ’456 onto Terentieva’s protective coating. See Petition, pp. 30, 43.
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`However, as noted above, the environmental barrier layer of Eaton ’456 “also
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`functions as a thermal barrier layer.” GE-1006, 2:49-50. Thus, the Petition
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`effectively proposes placing a layer that functions as a thermal barrier layer onto
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`Terentieva’s protective coating.
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`42. A POSITA would not have been motivated to make this combination
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`of layers, at least because a POSITA would have recognized that placing a thermal
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`barrier layer onto Terentieva’s protective coating would hinder or destroy the
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`healing functionality of the protective coating by decreasing the temperature where
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`Terentieva’s coating would be placed relative to the outer surface of the entire
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`coating exposed to the hot flowing gas.
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`43. The structure propose