Thermal barrier coatings including c mas-resistant thermal barrier coating layers

The present disclosure relates to thermal barrier coatings for high temperature mechanical systems.

For example, parts of hot mechanical systems, such as gas turbine engines, must operate in harsh environments. For example, the blades and fixed blades of a high-pressure turbine exposed to hot gases in a commercial aircraft engine typically have a metal surface temperature of about 1000 ° C and a short-term peak as high as 1100 ° C. .. Typical components of high temperature mechanical systems include Ni or Co based superalloy substrates. To reduce the temperature received by the substrate, the substrate can be coated with a thermal barrier coating (TBC). The thermal barrier coating can include a topcoat of insulating ceramic that is bonded to the substrate by the underlying metal bonding layer. TBC is usually applied by either air plasma spraying or electron beam physical vapor deposition, often in layers of yttria-stabilized zirconia (YSZ) with a thickness of about 100-500 μm. The characteristics of YSZ include low thermal conductivity, high oxygen permeability, and a relatively large coefficient of thermal expansion. YSZ TBC also becomes "strain resistant" and further reduced thermal conductivity, typically by depositing structures containing numerous pores and / or passages.

<p> Economic and environmental concerns, namely the desire to improve efficiency and reduce emissions, continue to drive the development of advanced gas turbine engines with higher inlet temperatures. As the turbine inlet temperature continues to rise, TBC with improved temperature stability is required.</p>

<p> In general, the present disclosure covers thermal barrier coatings (TBCs) that include at least one CMAS resistant TBC layer. CMAS is a calcia-magnesia-alumina-silicate deposit derived from the inhalation of silica-based minerals (dust, sand, volcanic ash, runway debris, etc.) associated with the intake of air from gas turbine engines.</p><p> The CMAS resistant TBC layer can include a TBC composition in combination with the CMAS resistant composition. In some embodiments, the TBC composition is in yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, and hafnia stabilized with at least three rare earth oxides. Can include at least one of. The CMAS resistant composition can include alumina, silica, and at least one rare earth oxide. Additional or instead, the CMAS resistant TBC layer is tantalum oxide (Ta).₂O₅), Titanium dioxide (TiO₂), Hafnium silicate (HfSiO)₄), Alkaline oxides, alkaline earth oxides, or combinations thereof.</p><p> In some embodiments, the TBC can include a single CMAS resistant TBC layer alone or in combination with a binding layer.</p><p> In other embodiments, the TBC comprises, in addition to the CMAS resistant TBC layer, at least one other layer, such as a layer containing the TBC composition. The layer containing the TBC composition may or may not provide additional CMAS resistance to TBC. In some embodiments, the TBC composition is in yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or hafnia stabilized with at least three rare earth oxides. Includes at least one of.</p><p> In some cases, TBC can include alternating layered structures with alternating TBC composition layers and CMAS resistant TBC layers. For example, the TBC can include a layer containing a first TBC composition, a CMAS resistant TBC layer, and a layer containing a second TBC composition. Such an alternating layer structure can be extended to any number of layers, and the outer layer of TBC can include a layer containing the TBC composition or a CMAS resistant TBC layer.</p><p> In one aspect, the present disclosure is directed to articles comprising a superalloy substrate and a CMAS resistant TBC layer overlaid on the superalloy substrate. According to this aspect of the present disclosure, the CMAS resistant TBC layer comprises from about 50 wt% to about 90 wt% TBC composition and from about 10 wt% to about 50 wt% CMAS resistant composition. In some embodiments, the TBC composition is in yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or hafnia stabilized with at least three rare earth oxides. Includes at least one of. In some embodiments, the CMAS resistant composition comprises alumina, silica, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb. Or includes at least one oxide in Lu.</p><p> In another aspect, the present disclosure is directed to a superalloy substrate and an article comprising TBC overlying the superalloy substrate. According to this aspect of the present disclosure, the TBC comprises a layer containing a first TBC composition overlaid on a substrate and a CMAS resistant TBC layer overlaid on a layer containing the first TBC composition. Including. In some embodiments, the first TBC composition is yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or stabilized with at least three rare earth oxides. Includes at least one of Hafnia. According to this aspect of the present disclosure, the CMAS resistant TBC layer comprises a second TBC composition and a CMAS resistant composition. In some embodiments, the second TBC composition is yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or stabilized with at least three rare earth oxides. Includes at least one of Hafnia. In some embodiments, the CMAS resistant composition comprises alumina, silica, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb. Or includes at least one oxide in Lu.</p><p> In a further embodiment, the present disclosure discloses a superalloy substrate, a layer containing a plurality of first TBC compositions overlying the superalloy substrate, and a plurality of CMAS resistant TBCs overlying the superalloy substrate. Targets articles containing layers. According to this aspect of the present disclosure, the first TBC composition is yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or stabilized with at least three rare earth oxides. Includes at least one of the Hafnia. In some embodiments, the plurality of CMAS resistant TBC layers comprises a second TBC composition and a CMAS resistant composition. The second TBC composition is yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or at least one of hafnia stabilized with at least three rare earth oxides. Can be included. The CMAS resistant composition comprises alumina, silica, and at least one of Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb or Lu. Can include with one oxide. Further, according to this aspect of the present disclosure, each one of the plurality of CMAS resistant TBC layers is staggered with each one of the layers containing the plurality of TBC compositions.</p><p> In another aspect, the present disclosure relates to a method comprising forming a CMAS resistant TBC layer overlying a superalloy substrate. According to this aspect of the present disclosure, the CMAS resistant layer comprises from about 50 wt% to about 90 wt% TBC composition and from about 10 wt% to about 50 wt% CMAS resistant composition. In some examples, the TBC composition is in yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or hafnia stabilized with at least three rare earth oxides. Includes at least one. In some examples, the CMAS resistant composition is composed of alumina, silica, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb or Contains at least one oxide in Lu.</p><p> In a further embodiment, the present disclosure forms a layer containing a first TBC composition overlying the superalloy substrate and a CMAS resistant TBC layer overlying the layer containing the first TBC composition. Target methods that include things. According to this aspect of the present disclosure, the first TBC composition is stable with yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or at least three rare earth oxides. Includes at least one of the transformed Hafnia. Further, according to this aspect of the present disclosure, the CMAS resistant TBC layer comprises a second TBC composition and a CMAS resistant composition. In some embodiments, the second TBC composition is yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or stabilized with at least three rare earth oxides. Includes at least one of Hafnia. In some embodiments, the CMAS resistant composition comprises alumina, silica, Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Yb, Dy, Ho, Er, Tm, Tb. Or includes at least one oxide in Lu.</p><p> Details of one or more embodiments are shown in the accompanying drawings and in the description below. Other features, objectives and advantages of the present disclosure will be apparent from the description and drawings, as well as from the claims.</p>

<figref num="1">It is a figure which shows the cross-sectional conceptual diagram explaining the example of the article which comprises the base material, the bonding layer which overlaps with said a base material, and CMAS resistant TBC layer which overlaps with said | bonding layer.</figref>

<figref num="2">An example of an article comprising a base material, a binding layer overlaid on the base material, a layer containing a TBC composition overlaid on the binding layer, and a CMAS-resistant TBC layer overlaid on a layer containing the TBC composition. It is a figure which shows the cross-sectional conceptual diagram to explain.</figref>

<figref num="3">A substrate, a binding layer overlaid on the substrate, a layer containing a first TBC composition overlaid on the binding layer, a CMAS resistant TBC layer overlaid on a layer containing the first TBC composition. , And a cross-sectional conceptual diagram illustrating an example of an article comprising a layer containing a second TBC composition overlaid on the CMAS resistant TBC layer.</figref>

<figref num="4">A substrate, a layer containing a first TBC composition overlaid on the substrate, a first CMAS resistant TBC layer overlaid on a layer containing the first TBC composition, the first CMAS resistant A cross-sectional conceptual diagram illustrating an example of an article comprising a layer containing a second TBC composition overlaid on a TBC layer and a second CMAS resistant TBC layer overlaid on a layer containing the second TBC composition. It is a figure which shows.</figref>

<figref num="5">An example of an article comprising a base material, a binding layer overlapping the base material, a layer containing a plurality of TBC compositions overlapping the binding layer, and a plurality of CMAS-resistant TBC layers overlapping the binding layer will be described. It is a figure which shows the cross-sectional conceptual diagram, in which each layer of the layer containing a plurality of TBC compositions is alternated with each layer of a CMAS resistant TBC layer.</figref>

In general, the present disclosure covers thermal barrier coatings (TBCs) that include at least one CMAS resistant TBC layer. CMAS is a calcia-magnesia-alumina-silicate deposit derived from the inhalation of silica-based minerals (dust, sand, volcanic ash, runway debris, etc.) associated with the uptake of air in gas turbine engines.

There is a constant demand for increased operating efficiency (eg, fuel efficiency) in search of reduced operating costs for gas turbine engines. Operating a gas turbine engine at a higher temperature is one method for improving the operating efficiency of the engine. As turbine inlet temperatures continue to rise, new barrier coatings, such as new TBCs, that can withstand the temperatures at which gas turbine engine components are exposed are required. TBCs can be deposited as porous or columnar structures, which increase stress tolerance and reduce the thermal conductivity of TBCs as compared to non-porous TBCs. However, this porous TBC structure can be vulnerable to damage.

Higher turbine inlet temperatures, for example, yttria-stabilized zirconia, when CMAS is formed by the inhalation of silica-based minerals (dust, sand, volcanic ash, runway debris, etc.) associated with the uptake of gas turbine engine air. May lead to damage to the porous TBC containing. Some CMAS deposits have a melting point of about 1200 ° C to about 1250 ° C (about 2200 ° F to about 2300 ° F). Advanced gas turbine engines operate at TBC surface temperatures above the melting point of CMAS, and therefore CMAS can melt on the surface of TBC, which means that CMAS penetrates into the pores of the porous TBC. Allows you to. When the TBC-coated component is cooled to a temperature below the melting point of the CMAS, the CMAS solidifies, which can distort the TBC and shorten the useful life of the TBC. Filling the pores of the TBC with molten CMAS can also increase the thermal conductivity of the TBC, which is detrimental to the performance of the TBC and to the elevated temperature of the substrate of the component. May be exposed.

Furthermore, in embodiments where the TBC comprises yttria-stabilized zirconia, the molten CMAS may dissolve the TBC along the grain boundaries of the yttria-stabilized zirconia and is lower, depending on the chemical phenomenon of melting. Zirconia with yttria content can precipitate from the melted solution. Zirconia with this lower yttria content may reduce the effectiveness of TBC as compared to TBC with zirconia and higher content yttria.

According to the embodiments of the present disclosure, the TBC can include a CMAS resistant TBC layer containing the TBC composition in combination with the CMAS resistant composition. In some embodiments, the TBC composition is in yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or hafnia stabilized with at least three rare earth oxides. Can include at least one of. The CMAS resistant composition can include alumina, silica, and at least one rare earth oxide. In some embodiments, the CMAS resistant TBC layer further comprises tantalum oxide (Ta).₂O₅), Titanium dioxide (TiO₂), Hafnium silicate (HfSiO)₄), Alkaline oxide, or at least one of alkaline earth oxides.

The CMAS resistant TBC layer can provide TBC with increased resistance to the harmful effects of CMAS. In some embodiments, at least one component in the CMAS resistant TBC layer reacts with the component of CMAS to form a solid or highly viscous reaction product, which reaction product is resistant to CMAS by molten CMAS. Reduces or substantially eliminates penetration of the TBC layer into pores or cracks. In some examples, the reaction product between CMAS and the components in the CMAS resistant TBC layer can form a reaction layer on the surface of the CMAS resistant TBC layer, which reaction layer is CMAS by molten CMAS. May help delay penetration into pores or cracks in resistant TBC layers.

In addition or instead, the CMAS resistant TBC layer is substantially non-porous, which physically suppresses or prevents the penetration of CMAS into the pores or crevices of the underlying layer, such as the layer containing the TBC composition. It can be formed as a layer of sex.

In some embodiments, the TBC can include another layer in addition to the CMAS resistant TBC layer. For example, the TBC can include a layer formed from a TBC composition overlaid on a substrate and a CMAS resistant TBC layer overlaid on a layer containing the TBC composition. As another example, TBC can include multiple CMAS resistant TBC layers that are staggered with layers containing multiple TBC compositions. In some embodiments, a TBC containing more than one layer can contribute to the insulation provided by the TBC to the substrate on which the TBC is deposited. For example, a TBC containing multiple layers can have interfaces between two different materials (eg, a CMAS resistant TBC layer and a layer containing a TBC composition), and these interfaces are TBCs containing only a single layer. It can contribute to the reduced thermal conductivity as compared with.

Although not desired to be constrained by theory, the interface between two different layers can reduce the thermal conductivity of the coating as the interface between the layers provides phonon scattering points. Therefore, in some embodiments, the CMAS resistant TBC layer provides protection from CMAS and also reduces the thermal conductivity of TBC as compared to coatings that do not contain the CMAS resistant TBC layer.

FIG. 1 shows a cross-sectional view of an example of article 10 used in a high temperature mechanical system. Article 10 comprises TBC14 applied to substrate 12. TBC14 includes a binding layer 16 overlaid on the substrate 12 and a CMAS resistant TBC layer 18 overlaid on the binding layer 16.

The substrate 12 is a component of a high temperature mechanical system, such as a gas turbine engine. In some embodiments, the substrate 12 comprises a superalloy. The base material 12 formed from the superalloy can include alloys based on Ni, Co, Ni / Fe and the like. Substrate 12 formed from superalloy, as is well known in the art, contains other additive components to alter its mechanical properties such as toughness, hardness, temperature stability, corrosion resistance and oxidation resistance. Can include. For example, those available under the trade name MAR-M247 from Martin-Marietta (Bethesda, Maryland) and those available under the trade names CMSX-4 and CMSX-10 from Cannon-Muskegon (Muskegon, Michigan). Any useful superalloy, including, etc., can be utilized in the substrate 12.

As shown in FIG. 1, the article 10 can include a binding layer 16 formed on the substrate 12. Although not shown in FIG. 1, in other embodiments, the article 10 may not include the binding layer 16. The binding layer 16 can improve the adhesiveness between the base material 12 and the layer overlapping the binding layer 16 (for example, the CMAS resistant TBC layer in FIG. 1). The bond layer 16 can include any useful material that improves the adhesion between the substrate 12 and the underlying layer.

For example, if the substrate 12 is a superalloy, the bond layer 16 may be an MCrAlY alloy (where M is Ni, Co or NiCo), (unmodified or Pt, Cr, Hf, Zr, Y, Β-NiAl nickel aluminide alloy (modified with Si and combinations thereof), γ- (unmodified or modified with Pt, Cr, Hf, Zr, Y, Si, and combinations thereof) Ni + γ'-Ni₃Alloys such as Al nickel aluminide alloys can be included.

The composition and resulting phase composition of the bond layer 16 is selected based on several considerations, including the chemical composition and phase structure of the layer overlaid on the substrate 12 and the bond layer 16 (CMAS resistant TBC layer 18 in FIG. 1). be able to. For example, the base material 12 is γ-Ni + γ'-Ni.₃When containing a superalloy with an Al phase structure, the bond layer 16 is γ-Ni + γ'-Ni to better match the coefficient of thermal expansion of the superalloy substrate 12.₃It can include the phase composition of Al. Thereby, the mechanical stability (adhesiveness) between the bonding layer 16 and the base material 12 can be increased.

In some embodiments, article 10 does not include a binding layer 16. For example, in some embodiments, the CMAS resistant TBC layer 18 is formed directly on the substrate 12. Article 10 may not include the binding layer 16 if the CMAS resistant TBC layer 18 and substrate 12 are sufficiently chemically and / or mechanically compatible. For example, in an embodiment in which the CMAS resistant TBC layer 18 and the substrate 12 adhere to each other sufficiently strongly, the article 10 may not include the binding layer 16. Furthermore, in embodiments where the coefficients of thermal expansion of the substrate 12 and the CMAS resistant TBC layer 18 are sufficiently similar, the article 10 may not include the binding layer 16. In this way, the CMAS resistant TBC layer 18 can be formed on the binding layer 16 or on the substrate 12. As used herein, the term "formed over" means that the first layer is formed directly on top of the second layer, the first layer is the second. Includes embodiments formed on top of a layer, with one or more intermediate layers between the first and second layers. For example, the term "CMAS resistant TBC layer 18 is formed over substrate 12" is based on the following embodiment: that is, an embodiment in which CMAS resistant TBC layer 18 is formed directly on substrate 12; CMAS. An embodiment in which the resistant TBC layer 18 is formed on the binding layer 16 and the binding layer 16 is formed on the substrate 12; and the CMAS resistant TBC layer 18 is between the substrate 12 and the CMAS resistant TBC layer 18. Includes embodiments formed on another intermediate layer (added to or in place of the binding layer 16) of. Similarly, as used herein, the term "overlapping" is similar to "formed over", i.e., the first layer overlying the second layer , It may be formed directly on top of the second layer, or it may be formed on another layer that overlaps the second layer.

TBC14 further comprises a CMAS resistant TBC layer 18 overlaid on the binding layer 16. The CMAS resistant TBC layer 18 can provide at least one of thermal protection (ie, adiabatic) and resistance to CMAS attack. The CMAS resistant TBC layer 18 generally includes a TBC composition and a CMAS resistant composition. The TBC composition can include, for example, at least one material selected to provide insulation against the substrate 12. In some embodiments, the TBC composition comprises yttria and / or hafnia alone or in combination with at least one other element or compound. For example, the TBC composition can include yttria and / or hafnia in combination with at least one rare earth oxide. Suitable rare earth oxides include Lu (lutetium), Yb (ytterbium), Tm (thulium), Er (erbium), Ho (formium), Dy (dysprosium), Tb (terbium), Gd (gadolinium), Eu ( Oxides of europium), Sm (samarium), Pm (promethium), Nd (neozim), Pr (placeodim), Ce (cerium), La (lantern), Y (ytterbium), or Sc (scandium) can be mentioned.

In some embodiments, the TBC composition comprises yttria-stabilized zirconia and / or yttria-stabilized hafnia. In some cases, yttria-stabilized zirconia or hafnia can contain from about 7 wt% to about 8 wt% yttria, the rest being zirconia and / or hafnia.

In some embodiments, the TBC composition comprises hafnia and / or zirconia stabilized with at least three rare earth oxides. The TBC composition can contain any relative amount of any combination of rare earth oxides.

In some examples, the TBC composition comprises a base oxide, a major dopant, a first codopant, and a second codopant. The base oxide can include at least one of zirconia and hafnia. The main dopant is present in a larger amount than either the first codopant or the second codopant (although not necessarily higher than the total amount of the first codopant and the second codopant). Ittelvia can be included. The first colactone can include samaria and the second colactone can be lutetia, scandia, ceria, gadolinia, neodymia or europia. ) Can contain at least one.

In some embodiments, the TBC composition comprising the base oxide, the primary dopant, the first co-dopant and the second co-dopant can preferably have low thermal conductivity. Although not desired to be constrained by theory, dopants can have different ionic radii or crystal lattice structures as compared to base oxide ions. By including such a dopant, lattice defects can be introduced into the crystal structure of the CMAS resistant TBC layer 18. For the purposes of considering this, lattice defects can be broadly divided into two categories: point defects and larger defects. Point defects such as substitutional defects, interstitial defects, and void defects can scatter high frequency phonons, while larger defects such as grain boundaries of crystals smaller than about 100 nm have lower frequency phonons. Can be scattered. In both cases, phonon scattering reduces the thermal conductivity of the CMAS resistant TBC layer 18.

Additional or instead, in some embodiments, the degree of sintering of the CMAS resistant TBC layer 18 at a given temperature is determined by including a particular rare earth element or combination of rare earth elements in the CMAS resistant TBC layer 18. It can also be lowered. For example, by incorporating a rare earth element having an ionic radius larger than that of yttrium, the amount of sintering at a predetermined temperature can be reduced as compared with the TBC layer containing yttria-stabilized zirconia. Although not desired to be constrained by theory, at a given temperature, the larger the ionic radius, the smaller the (ion's) diffusion coefficient can be. Since sintering is a process mainly related to diffusion, at a predetermined temperature, the smaller the diffusion coefficient, the lower the amount of sintering.

By minimizing or eliminating sintering, the thermal conductivity stability of the CMAS resistant TBC layer 18 can be improved beyond the service life of the article 10. In some examples, the thermal conductivity of the CMAS resistant TBC layer 18 can be reduced by depositing the CMAS resistant TBC layer 18 as a porous structure. The pores of the CMAS resistant TBC layer 18 are due to the reduced heat transfer area and the large difference in refractive index between the pores and the material forming the CMAS resistant TBC layer 18 (which reduces thermal transfer due to radiation). By providing), the thermal conductivity is reduced as compared to the non-porous TBC. Sintering can reduce the pores of the structure and thus increase the thermal conductivity of the CMAS resistant TBC layer 18 (via both radiation and conduction). Therefore, by protecting the pores of the CMAS resistant TBC layer 18 over repeated thermal cycles (ie, reducing sintering), the thermal conductivity of the CMAS resistant TBC layer 18 is increased by the CMAS resistant TBC layer 18 initially applied. Can help maintain at or near the level of.

In some embodiments, the TBC composition comprising the base oxide, the primary dopant, the first colactone, and the second colactone has a metastable tetragonal (t') phase configuration, a cubic (c) phase. It can include a composition, a mixture of t'and c phase configurations, or a composition selected to provide a phase composition of a compound.

As mentioned above, the main dopant can include ittelvia. In some examples, the main dopant can be essentially from Ittervia. As used herein, "consisting essentially of" means consisting of the listed elements (s) or compounds (s), but of the listed elements or compounds. Inclusion of impurities present in small amounts that does not substantially affect the properties is permissible. For example, purification of many rare earth elements is difficult, and therefore a rare earth element of a certain name may contain a small amount of other rare earth elements. This mixture is interpreted to be included in the phrase "becomes essential from". In some examples, the TBC composition comprises from about 2 mol% to about 40 mol% ittervia. In another example, the TBC composition comprises from about 2 mol% to about 20 mol% ittelvia, or from about 2 mol% to about 10 mol% ittelvia.

The TBC composition can also include a first codopant, the first codopant containing or consisting essentially of Samaria. In some examples, the TBC composition comprises from about 0.1 mol% to about 20 mol% Samaria. In another example, the TBC composition comprises from about 0.5 mol% to about 10 mol% Samaria, or from about 0.5 mol% to about 5 mol% Samaria.

The TBC composition can also include a second colactone, which can include at least one of lutecia, scandia, ceria, gadlinia, neodymia, or europia. In some examples, the TBC composition comprises from about 0.1 mol% to about 20 mol% of a second colactone. In another example, the TBC composition comprises from about 0.5 mol% to about 10 mol% of a second codopant, or from about 0.5 mol% to about 5 mol% of a second codopant.

The overall composition of the TBC composition can be selected to provide the desired phase composition. As mentioned above, the available phase configurations include metastable tetragonal, cubic, and RE.₂O₃-ZrO₂(And / or HfO₂) Compounds containing compounds, such as RE₂Zr₂O₇And RE₂Hf₂O₇(Here, RE is a rare earth element).

In some embodiments, RE₂O₃-ZrO₂(And / or HfO₂) To achieve the phase composition of the compound, the TBC composition is composed of about 20 mol% to about 40 mol% of the main dopant, about 10 mol% to about 20 mol% of the first co-dopant, about 10 mol% to about. It can contain 20 mol% of a second codopant, as well as the remaining base oxide and any impurities, if any.

In some embodiments, in order to achieve a cubic phase composition, the TBC composition comprises from about 4 mol% to about 10 mol% of major dopant and from about 1 mol% to about 5 mol% of first codopant. , About 1 mol% to about 5 mol% of the second codopant, as well as the remaining base oxide and any impurities, if any.

In some embodiments, in order to achieve a metastable tetragonal phase composition, the TBC composition is a primary dopant of about 2 mol% to about 5 mol%, a first of about 0.5 mol% to about 3 mol%. Co-dopant, about 0.5 mol% to about 3 mol% second co-dopant, as well as the remaining base oxide and any impurities, if any.

As mentioned above, the CMAS resistant TBC layer further comprises a CMAS resistant composition. The CMAS resistant composition can include, for example, alumina, silica, and at least one rare earth oxide. At least one rare earth oxide is one of Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Pm, Nd, Pr, Ce, La, Y or Sc. Can be mentioned. In some embodiments, the at least one rare earth oxide contained in the CMAS resistant composition may be identical to at least one rare earth oxide contained in the TBC composition. In other embodiments, the TBC composition comprises at least one rare earth oxide that differs from at least one rare earth oxide in the CMAS resistant composition.

In some embodiments, the CMAS resistant composition can comprise from about 1 mol% to about 99 mol% at least one rare earth oxide, as well as from about 1 mol% to about 99 mol% alumina and silica. In other embodiments, the CMAS resistant composition can include at least one rare earth oxide from about 10 mol% to about 90 mol%, as well as about 10 mol% to about 90 mol% alumina and silica. In other embodiments, the CMAS resistant composition can comprise from about 20 mol% to about 80 mol% at least one rare earth oxide, as well as from about 20 mol% to about 80 mol% alumina and silica.

In some embodiments, the CMAS resistant composition is optionally TiO.₂, Ta₂O₅, HfSiO₄, Alkaline oxides, and at least one of alkaline earth oxides. Additional ingredients can be added to the CMAS resistant composition to modify one or more desired properties of the CMAS resistant TBC layer 18. For example, additional components can increase or decrease the rate of reaction of the CMAS resistant TBC layer 18 with CMAS, modify the viscosity of the reaction product from the reaction of CMAS with the CMAS resistant TBC layer 18, and adjacent layers. For example, the adhesiveness of the CMAS-resistant TBC layer 18 to the binding layer 16 can be enhanced, and the chemical stability of the CMAS-resistant TBC layer 18 and the like can be increased or decreased.

The CMAS resistant TBC layer 18 can contain a mixture or alloy of the TBC composition and the CMAS resistant composition. In general, the CMAS resistant TBC layer 18 can include from about 1 wt% to about 99 wt% TBC composition and from about 1 wt% to about 99 wt% CMAS resistant composition. In some embodiments, the CMAS resistant TBC layer 18 comprises from about 50 wt% to about 90 wt% TBC composition and from about 10 wt% to about 50 wt% CMAS resistant composition. In other embodiments, the CMAS resistant TBC layer 18 comprises from about 50 wt% to about 70 wt% TBC composition and from about 30 wt% to about 50 wt% CMAS resistant composition.

In addition, the CMAS resistant TBC layer 18 can include substantially dense microstructures, porous microstructures, or columnar microstructures. The CMAS resistant TBC layer 18 can be deposited, for example, by plasma spraying, physical vapor deposition (PVD), chemical vapor deposition (CVD), or slurry deposition. One of the PVDs that can be used to deposit the CMAS resistant TBC layer 18 is electron beam physical vapor deposition (EB-PVD). One of the EB-PVDs that can be used to deposit the CMAS resistant TBC layer 18 is directed vapor deposition (DVD). In DVD, the energy source creates an electron beam that vaporizes a portion of the target material that contains components to be deposited in the CMAS resistant TBC layer 18. The vaporized material is then directed to the substrate 12 using a transonic gas stream. This allows for greater deposition efficiency compared to EB-PVD and also allows for non-line-of-sight deposition. In some embodiments, the CMAS resistant TBC layer 18 comprises columnar microstructures and is deposited using EB-PVD or DVD.

In some embodiments, the CMAS resistant TBC layer 18 can be deposited using plasma deposition. If the CMAS resistant TBC layer 18 contains porous microstructures, the material forming the CMAS resistant TBC layer 18 is co-located with a sacrificial material that is removed after the CMAS resistant TBC layer 18 is deposited to form pores, such as polyester. Can be deposited.

The CMAS resistant TBC layer 18 can generally have any thickness. In some examples, the CMAS resistant TBC layer 18 contains a thickness of about 0.5 mils to about 20 mils (1 mil equals 0.001 inch).

As mentioned above, in some examples, the components in the CMAS resistant TBC layer 18 can react with the CMAS in contact with the layer 18 to form a solid or highly viscous reaction product. The reaction product may have a melting temperature significantly higher than CMAS (eg, higher than about 1200-1250 ° C). A solid or highly viscous reaction product is desirable as the CMAS resistant TBC layer 18 is consumed as it reacts with CMAS. If, for example, the reaction product of the CMAS resistant TBC layer 18 and CMAS is a relatively low viscosity liquid, the low viscosity liquid is in the pores or cracks of the porous or columnar CMAS resistant TBC layer 18. The CMAS resistant TBC layer 18 is designed to prevent this from happening.

However, if the reaction product is solid or highly viscous, the reaction layer will be on or near the surface of the CMAS resistant TBC layer 18 (eg, pores or cracks in the CMAS resistant TBC layer 18 near the outer surface of layer 18). This can occur within), which can slow down the reaction rate between CMAS and the CMAS resistant TBC layer 18. That is, once a solid or highly viscous reaction layer occurs on or near the surface of the CMAS resistant TBC layer 18, any further reaction is diffusion for CMAS to encounter the CMAS resistant TBC layer 18 through the reaction layer. Or, the reaction between the CMAS-resistant TBC layer 18 and CMAS may be slowed down because the components of the CMAS-resistant TBC layer 18 require diffusion to encounter CMAS through the reaction layer. In either case, once a solid or highly viscous reaction layer is formed on the surface of the CMAS resistant TBC layer 18, diffusion is expected to be the slowest process of the CMAS or CMAS resistant TBC layer 18. Diffusion of either component is expected to be the rate-determining step in the reaction.

FIG. 2 is a cross-sectional view illustrating another example of article coated with TBC containing a CMAS resistant TBC layer. In contrast to FIG. 1, which shows a TBC 14 containing a single CMAS resistant TBC layer 18 formed on the binding layer 16, the article 20 described in FIG. 2 comprises a multi-layered TBC 24. The multilayer TBC24 is a CMAS-resistant TBC that is superposed on a bonding layer 16 that is superposed on the base material 12, a layer 26 that contains a TBC composition that is superposed on the binding layer 16, and a layer 26 that is superposed on the TBC composition. Includes layer 28.

The base material 12 and the bonding layer 16 can contain the same composition as previously described for FIG. For example, the substrate 12 can contain a superalloy based on Ni, Co, Ni / Fe, etc., and the bond layer 16 improves the adhesion between the substrate 12 and the layer 26 containing the TBC composition. Can include alloys. As an example, the bond layer 16 is an MCrAlY alloy (where M is Ni, Co or NiCo), a β-NiAl nickel aluminum alloy (unmodified or Pt, Cr, Hf, Zr, Y, Si). , And modified with a combination of these), γ-Ni + γ'-Ni₃Al nickel aluminide alloys (unmodified or modified with Pt, Cr, Hf, Zr, Y, Si, and combinations thereof) and the like can be included.

FIG. 2 illustrates a multi-layer TBC24 that includes a bond layer 16, but in other embodiments, the multi-layer TBC24 does not have to include a bond layer 16 and is based on a layer 26 that contains a TBC composition. It can be formed directly on the material 12. The multilayer TBC24 may not include the bonding layer 16 if the layer 26 and the base material 12 containing the TBC composition are sufficiently chemically and / or mechanically compatible. For example, in an embodiment in which the layer 26 containing the TBC composition and the base material 12 adhere to each other sufficiently strongly, the multilayer TBC24 may not include the bonding layer 16. Furthermore, in embodiments where the coefficients of thermal expansion of the substrate 12 and the layer 26 containing the TBC composition are sufficiently similar, the multilayer TBC 24 may not include the bonding coat 16.

The multilayer TBC24 further includes a layer 26 containing the TBC composition. The TBC composition in layer 26 containing the TBC composition can include, for example, at least one material selected to provide insulation to the substrate 12. In some embodiments, the TBC composition comprises yttria and / or hafnia alone or in combination with at least one other element or compound. For example, the TBC composition can include yttria and / or hafnia in combination with at least one rare earth oxide. Suitable rare earth oxides include oxides of Lu, Yb, Tm, Er, Ho, Dy, Tb, Gd, Eu, Sm, Pm, Nd, Pr, Ce, La, Y or Sc.

In some embodiments, the TBC composition comprises yttria-stabilized zirconia and / or yttria-stabilized hafnia. In some cases, yttria-stabilized zirconia or hafnia can include about 7 wt% to about 8 wt% yttria, and the remaining zirconia and / or hafnia.

In some embodiments, the TBC composition comprises hafnia and / or zirconia stabilized with at least three rare earth oxides. The TBC composition can contain any relative amount of any combination of rare earth oxides.

In some examples, the TBC composition comprises a base oxide, a major dopant, a first codopant, and a second codopant. The base oxide can include at least one of zirconia and hafnia. The main dopant is present in a larger amount than either the first codopant or the second codopant (although not necessarily higher than the total amount of the first codopant and the second codopant). Ittelvia can be included. The first co-lactone can include Samaria and the second co-lactone can include at least one of lutecia, scandia, ceria, gadlinia, neodymia or europia.

In some embodiments, the TBC composition comprising the base oxide, the primary dopant, the first codopant, and the second codopant can preferably have low thermal conductivity. Although not desired to be constrained by theory, dopants can have ionic radii or crystal lattice structures that differ from the base oxide ions. By including such a dopant, lattice defects can be introduced into the crystal structure of the layer 26 containing the TBC composition. For the purposes of considering this, lattice defects can be broadly divided into two categories: point defects and larger defects. Point defects such as substitutional defects, interstitial defects, and void defects can scatter high frequency phonons, while larger defects such as grain boundaries of crystals smaller than about 100 nm have lower frequency phonons. Can be scattered. In both cases, phonon scattering reduces the thermal conductivity of layer 26 containing the TBC composition.

Additional or alternative, in some embodiments, a layer containing a TBC composition at a predetermined temperature by including a particular rare earth element or combination of rare earth elements in the layer 26 containing the TBC composition. The degree of sintering of 26 can be reduced. For example, by incorporating a rare earth element having an ionic radius larger than that of yttrium, the amount of sintering can be reduced as compared with the yttria-stabilized zirconia-containing TBC layer at a predetermined temperature. Although not desired to be constrained by any theory, larger ionic radii can result in lower (ionic) diffusion coefficients at a given temperature. Since sintering is a process mainly related to diffusion, the smaller the diffusion coefficient, the lower the amount of sintering at a predetermined temperature.

By minimizing or removing the sintering, the stability of the thermal conductivity of the layer 26 containing the TBC composition can be improved beyond the service life of the article 10. In some examples, the thermal conductivity of layer 26 containing the TBC composition can be reduced by depositing layer 26 containing the TBC composition as a porous structure. The pores in the layer 26 containing the TBC composition are due to the reduced heat transfer area and the large difference in refractive index between the pores and the material forming the layer 26 containing the TBC composition (which is By providing (which can reduce heat transfer due to radiation), it reduces thermal conductivity compared to non-porous TBC. Sintering can reduce the pores of the structure and thus increase the thermal conductivity of layer 26 containing the TBC composition (via both radiation and conduction). Therefore, to protect the pores of layer 26 containing the TBC composition (ie, reduce sintering) over repeated thermal cycles, the thermal conductivity of layer 26 containing the TBC composition was first applied. May help maintain at or near the level of CMAS resistant TBC layer 18.

In some embodiments, the TBC composition comprising the base oxide, the primary dopant, the first colactone, and the second colactone has a metastable tetragonal (t') phase configuration, a cubic (c) phase. It can include a composition, a mixture of t'and c phase configurations, or a composition selected to provide a phase composition of a compound.

As mentioned above, the main dopant can include ittelvia. In some examples, the main dopant can be essentially from Ittervia. As used herein, "consisting essentially of" means consisting of the listed elements (s) or compounds (s), but of the listed elements or compounds. Inclusion of impurities present in small amounts that does not substantially affect the properties is permissible. For example, purification of many rare earth elements is difficult, and therefore a rare earth element of a certain name may contain a small amount of other rare earth elements. This mixture is interpreted to be included in the phrase "becomes essential from". In some examples, the TBC composition comprises from about 2 mol% to about 40 mol% ittervia. In another example, the TBC composition comprises from about 2 mol% to about 20 mol% ittelvia, or from about 2 mol% to about 10 mol% ittelvia.

The TBC composition can also include a first codopant, the first codopant which may contain or consist essentially of Samaria. In some examples, the TBC composition comprises from about 0.1 mol% to about 20 mol% Samaria. In another example, the TBC composition comprises from about 0.5 mol% to about 10 mol% Samaria, or from about 0.5 mol% to about 5 mol% Samaria.

The TBC composition can also include a second colactone, which can include at least one of lutecia, scandia, ceria, gadlinia, neodymia, or europia. In some examples, the TBC composition comprises from about 0.1 mol% to about 20 mol% of a second codopant. In another example, the TBC composition comprises from about 0.5 mol% to about 10 mol% of a second codopant, or from about 0.5 mol% to about 5 mol% of a second codopant.

The overall composition of the TBC composition can be selected to provide the desired phase composition. As mentioned above, the available phase configurations include metastable tetragonal, cubic, and RE.₂O₃-ZrO₂(And / or HfO₂) Compounds containing compounds, such as RE₂Zr₂O₇And RE₂Hf₂O₇(Here, RE is a rare earth element).

In some embodiments, RE₂O₃-ZrO₂(And / or HfO₂) To achieve the phase composition of the compound, the TBC composition is composed of about 20 mol% to about 40 mol% of the main dopant, about 10 mol% to about 20 mol% of the first co-dopant, about 10 mol% to about. It can contain 20 mol% of a second codopant, as well as the remaining base oxide and any impurities, if any.

In some embodiments, in order to achieve a cubic phase composition, the TBC composition comprises from about 4 mol% to about 10 mol% of major dopant and from about 1 mol% to about 5 mol% of first codopant. , About 1 mol% to about 5 mol% of the second codopant, as well as the remaining base oxide and any impurities, if any.

In some embodiments, in order to achieve a metastable tetragonal phase composition, the TBC composition is a primary dopant of about 2 mol% to about 5 mol%, a first of about 0.5 mol% to about 3 mol%. Co-dopant, about 0.5 mol% to about 3 mol% second co-dopant, as well as the remaining base oxide and any impurities, if any.

In some embodiments, instead of being deposited as a porous layer, the layer 26 containing the TBC composition can be deposited as a substantially non-porous layer or a columnar microstructure-containing layer. .. In either case, the layer 26 containing the TBC composition can be deposited, for example, by plasma spraying, PVD, CVD, or slurry deposition. One of the PVDs that can be used to deposit layer 26 containing the TBC composition is EB-PVD. One of the EB-PVDs that can be used to deposit layer 26 containing the TBC composition is DVD. In DVD, the energy source creates an electron beam that vaporizes a portion of the target material that contains components to be deposited in layer 26 containing the TBC composition. The vaporized material is then directed to the substrate 12 using a transitional gas stream. This allows for greater deposition efficiency compared to EB-PVD and also allows non-direct deposition.

In some embodiments, the layer 26 containing the TBC composition can be deposited using plasma deposition. When the layer 26 containing the TBC composition contains a porous microstructure, the material forming the layer 26 containing the TBC composition is removed after the layer 26 containing the TBC composition is deposited to form pores. It can be co-deposited with sacrificial materials such as polyester.

The layer 26 containing the TBC composition can be formed to any thickness that provides a planned amount of protection against the substrate 12. In some embodiments, the layer 26 containing the TBC composition can have a thickness of about 0.5 mils to about 20 mils.

The multilayer TBC24 also includes a CMAS resistant TBC layer 28 which is superposed on the layer 26 containing the TBC composition in the embodiment shown in FIG. The CMAS resistant TBC layer 28 can include any of the compositions and microstructures described for the CMAS resistant TBC layer 18 shown in FIG. For example, the CMAS resistant TBC layer 28 can contain a mixture or alloy of the TBC composition and the CMAS resistant composition. The TBC composition in the CMAS resistant TBC layer 28 is a TBC composition described herein, eg, yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or at least three. It can contain any of the Hafnia stabilized with one rare earth oxide. An example of a TBC composition suitable for use in CMAS resistant TBC layer 28 was previously described in FIG. In some embodiments, the TBC composition in the CMAS resistant TBC layer 28 may be substantially similar to the TBC composition in the layer 26 containing the TBC composition. In other embodiments, the TBC composition in the CMAS resistant TBC layer 28 may differ from the TBC composition in the layer 26 containing the TBC composition.

The CMAS resistant TBC layer 28 also comprises a CMAS resistant composition. As described above for the CMAS resistant TBC layer 18 of FIG. 1, the CMAS resistant composition can include alumina, silica, and at least one rare earth oxide. In some embodiments, the CMAS resistant composition can comprise from about 1 mol% to about 99 mol% at least one rare earth oxide, as well as from about 1 mol% to about 99 mol% alumina and silica. In other embodiments, the CMAS resistant composition can include at least one rare earth oxide from about 10 mol% to about 90 mol%, as well as about 10 mol% to about 90 mol% alumina and silica. In other embodiments, the CMAS resistant composition can comprise from about 20 mol% to about 80 mol% at least one rare earth oxide, as well as from about 20 mol% to about 80 mol% alumina and silica.

Optionally, the CMAS resistant composition may further include additives such as TiO.₂, Ta₂O₅, HfSiO₄, Alkaline oxides, or at least one of alkaline earth oxides. In some embodiments, the additive can be added to the CMAS resistant TBC layer 28 to modify one or more properties of the CMAS resistant TBC layer 28.

As described above with respect to the CMAS resistant TBC layer 18 of FIG. 1, the CMAS resistant TBC layer 28 may contain a mixture or alloy of the TBC composition and the CMAS resistant composition. For example, the CMAS resistant TBC layer 28 can include from about 1 wt% to about 99 wt% TBC composition and from about 1 wt% to about 99 wt% CMAS resistant composition. In some embodiments, the CMAS resistant TBC layer 28 comprises from about 50 wt% to about 90 wt% TBC composition and from about 10 wt% to about 50 wt% CMAS resistant composition. In other embodiments, the CMAS resistant TBC layer 28 comprises from about 50 wt% to about 70 wt% TBC composition and from about 30 wt% to about 50 wt% CMAS resistant composition.

The CMAS resistant TBC layer 28 can include substantially dense microstructures, porous microstructures, or columnar microstructures. The CMAS resistant TBC layer 28 can be deposited, for example, by plasma spraying, PVD, CVD, or slurry deposition. One of the PVDs that can be used to deposit the CMAS resistant TBC layer 28 is EB-PVD. One of the EB-PVDs that can be used to deposit the CMAS resistant TBC layer 28 is DVD.

The CMAS resistant TBC layer 28 can be formed to any suitable thickness where the layer 28 provides the expected protection against the substrate 12. In some embodiments, the CMAS resistant TBC layer 28 can be formed to a thickness of about 0.5 mils to about 20 mils.

In some embodiments, the multilayer TBC24 can provide greater thermal protection to the substrate 12 than a single layer of TBC composition similar to layer 26. For example, the multilayer TBC24 includes an interface between two layers containing different compositions (CMAS resistant TBC layer 26 and layer 24 containing the TBC composition). Although not desired to be constrained by theory, the interface between two layers with different compositions has a similar composition to the thermal conductivity of the multilayer TBC20, as the interface between the layers provides a phonon scattering point. It can be reduced compared to the single-layer TBC that has. The phonon scattering points, as a whole, reduce the effective thermal conductivity of the multilayer TBC20.

Further, as described above, the components in the CMAS resistant TBC layer 28 can react with CMAS which comes into contact with the layer 28 to form a solid or highly viscous reaction product. The reaction product can have a significantly higher melting point than CMAS (eg, higher than about 1200-1250 ° C). A solid or highly viscous reaction product is desirable as the CMAS resistant TBC layer 28 is consumed as it reacts with CMAS. For example, if the reaction product of the CMAS resistant TBC layer 28 and CMAS is a relatively low viscosity liquid, the low viscosity liquid will be a porous or columnar layer 26 as the CMAS resistant TBC layer 28 is consumed. The CMAS resistant TBC layer 28, which can penetrate the pores or cracks of the, is designed to prevent this very situation.

However, if the reaction product is solid or highly viscous, the reaction layer will be on or near the surface of the CMAS resistant TBC layer 28 (eg, pores or cracks in the CMAS resistant TBC layer 28 near the outer surface of the layer 28). (Inside), which can slow down the reaction rate between CMAS and CMAS-resistant TBC layer 28. That is, once a solid or highly viscous reaction layer occurs on or near the surface of the CMAS resistant TBC layer 28, any further reaction will diffuse for CMAS to encounter the CMAS resistant TBC layer 28 through the reaction layer. Or, the reaction between the CMAS-resistant TBC layer 28 and CMAS may be slowed down because the components of the CMAS-resistant TBC layer 18 require diffusion to encounter CMAS through the reaction layer. In either case, once a solid or highly viscous reaction layer is formed on the surface of the CMAS resistant TBC layer 28, diffusion is expected to be the slowest process of the CMAS or CMAS resistant TBC layer 28. Diffusion of either component is expected to be the rate-determining step in the reaction. In this manner, the CMAS resistant TBC layer 28 can provide CMAS resistance to the multilayer TBC24.

As shown in FIGS. 3, 4 and 5, in some embodiments, the TBC can include additional layers. For example, FIG. 3 illustrates an article 30 containing a substrate coated with a multilayer TBC34. In the embodiment shown in FIG. 3, the multilayer TBC34 comprises a binding layer 16, a layer 36 containing a first TBC composition overlying the binding layer 16, and a CMAS resistant TBC overlying the first layer 36. It comprises a layer 38 and a layer 40 containing a second TBC composition overlaid on the CMAS resistant TBC layer 38.

The base material 12 and the bonding layer 16 can contain the same compositions as previously described with respect to FIGS. 1 and 2. Further, in some embodiments, the multilayer TBC34 does not have to include the binding layer 16 and the first layer 36 can be formed directly on the substrate as described above.

The first layer 36 can contain any of the TBC compositions described herein. For example, the first layer 36 can include yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or hafnia stabilized with at least three rare earth oxides. .. As mentioned above, in some embodiments, the TBC composition can include a base oxide, a primary dopant, a first codopant, and a second codopant.

The first layer 36 can be formed as a substantially non-porous layer, as a porous layer, or as a columnar layer. In some embodiments, the first layer 36 can be deposited, for example, by plasma spraying, PVD, CVD, or slurry deposition. One of the PVDs that can be used to deposit layer 26 containing the TBC composition is EB-PVD. One of the EB-PVDs that can be used to deposit layer 26 containing the TBC composition is DVD. The first layer 36 can be formed to a thickness of about 0.5 mils to about 20 mils.

The CMAS resistant TBC layer 38 is layered on top of the first layer 36 and contains a TBC composition and a CMAS resistant composition. The TBC composition in the CMAS resistant TBC layer 38 is a TBC composition described herein, eg, yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or at least three. It can contain any of the Hafnia stabilized with one rare earth oxide. An example of a TBC composition suitable for use in CMAS resistant TBC layer 38 is described earlier with respect to FIG. In some embodiments, the TBC composition in the CMAS resistant TBC layer 38 is the TBC composition in the layer 36 containing the first TBC composition and the TBC in the layer 40 containing the second TBC composition. It may be substantially similar to at least one in the composition. In other embodiments, the TBC composition in the CMAS resistant TBC layer 38 may differ from the TBC composition in the first TBC-containing layer 36 and the second TBC composition-containing layer 40.

The CMAS resistant TBC layer 38 also comprises a CMAS resistant composition. As described above for the CMAS resistant TBC layer 18 of FIG. 1, the CMAS resistant composition can include alumina, silica, and at least one rare earth oxide. In some embodiments, the CMAS resistant composition can comprise from about 1 mol% to about 99 mol% at least one rare earth oxide, as well as from about 1 mol% to about 99 mol% alumina and silica. In other embodiments, the CMAS resistant composition can include at least one rare earth oxide from about 10 mol% to about 90 mol%, as well as 10 mol% to about 90 mol% alumina and silica. In other embodiments, the CMAS resistant composition can comprise from about 20 mol% to about 80 mol% at least one rare earth oxide, as well as from about 20 mol% to about 80 mol% alumina and silica.

Optionally, the CMAS resistant composition may further include additives such as TiO.₂, Ta₂O₅, HfSiO₄, Alkaline oxides, and alkaline earth oxides. In some embodiments, as described above, additives can be added to the CMAS resistant TBC layer 38 to modify one or more properties of the CMAS resistant TBC layer 38.

The CMAS resistant TBC layer 38 can contain a mixture or alloy of the TBC composition and the CMAS resistant composition. For example, the CMAS resistant TBC layer 28 can include from about 1 wt% to about 99 wt% TBC composition and from about 1 wt% to about 99 wt% CMAS resistant composition. In some embodiments, the CMAS resistant TBC layer 38 comprises from about 50 wt% to about 90 wt% TBC composition and from about 10 wt% to about 50 wt% CMAS resistant composition. In other embodiments, the CMAS resistant TBC layer 38 comprises from about 50 wt% to about 70 wt% TBC composition and from about 30 wt% to about 50 wt% CMAS resistant composition.

The CMAS resistant TBC layer 38 can include substantially dense microstructures, porous microstructures or columnar microstructures. The CMAS resistant TBC layer 38 can be deposited, for example, by plasma spraying, PVD, CVD, or slurry deposition. One of the PVDs that can be used to deposit the CMAS resistant TBC layer 38 is EB-PVD. One of the EB-PVDs that can be used to deposit CMAS resistant TBC layer 38 is DVD.

The CMAS resistant TBC layer 38 can be formed to any thickness suitable for the layer 38 to provide the desired protection against the substrate 12. In some embodiments, the CMAS resistant TBC layer 38 can be formed to a thickness of about 0.5 mils to about 20 mils.

The multilayer EBC34 further includes a layer 40 containing a second TBC composition. The second layer 40 can contain any of the TBC compositions described herein. For example, the second layer 40 can include yttria-stabilized zirconia, yttria-stabilized hafnia, zirconia stabilized with at least three rare earth oxides, or hafnia stabilized with at least three rare earth oxides. .. As mentioned above, in some embodiments, the TBC composition can include a base oxide, a major dopant, a first codopant, and a second codopant.

In some embodiments, the second layer 40 comprises a TBC composition similar to at least one of the first layer 36 and the CMAS resistant TBC layer 38. In other embodiments, the second layer 40 comprises a TBC composition different from at least one of the first layer 36 and the CMAS resistant TBC layer 38.

The second layer 40 can be formed as a substantially non-porous layer, as a porous layer, or as a columnar layer. In some embodiments, the second layer 40 can be deposited, for example, by plasma spraying, PVD, CVD, or slurry deposition. One of the PVDs that can be used to deposit layer 40 containing the second TBC composition is EB-PVD. One of the EB-PVDs that can be used to deposit the second layer 40 is a DVD.

The second layer 40 can be formed to any expected thickness. In some embodiments, the second layer 40 can have a thickness that is less than the thickness of the first layer 36. In other embodiments, the second layer 40 can have a thickness that is substantially equal to or greater than the thickness of the first layer 36. In some embodiments, the second layer 40 can have a thickness of about 0.5 mils to about 20 mils.

In some embodiments, the second layer 40 can reduce the rate at which CMAS reacts with the CMAS-resistant TBC layer 38 by reducing the rate at which CMAS contacts the CMAS-resistant TBC layer 38. The second layer 40 must pass for CMAS to contact the CMAS resistant TBC layer 38, similar to the solid or highly viscous reaction layer formed on the CMAS resistant TBC layer 28 (discussed with respect to FIG. 2). It can function as a layer that does not become. This reduction in effective reaction rate extends the life of the CMAS resistant TBC layer 38 and is first by the CMAS resistant TBC layer 38 as compared to article 30 which does not contain the layer 40 containing the second TBC composition. The protection provided to layer 36 can be increased. Therefore, in some embodiments, the combination of the presence of the second layer 40 and the formation of a solid or highly viscous reaction product from the reaction of the CMAS resistant TBC layer 38 with CMAS is a combination of the molten CMAS. Penetration of the first layer 26 into the pores or cracks can be substantially prevented.

Additional or instead, the multilayer TBC34 can provide greater thermal protection to the substrate 12 as compared to a single layer TBC having a composition similar to that of the first layer 36. For example, the multilayer TBC34 has two layers (between the first layer 36 and the CMAS resistant TBC layer 38 and between the CMAS resistant TBC layer 38 and the second layer 40) containing different compositions. Including the interface. Although not desired to be constrained by theory, the interface between two layers with different compositions becomes a single layer TBC with a similar composition, as the interface between the layers provides a phonon scattering point. In comparison, the thermal conductivity of the multilayer TBC34 can be reduced. The phonon scattering points reduce the effective thermal conductivity of the multilayer TBC34 as a whole.

In some embodiments as shown in FIG. 4, article 50 may include a substrate 12 coated with a multilayer TBC54 with additional layers. In the example shown in FIG. 4, the multilayer TBC54 has a layer 56 containing a first TBC composition, a first CMAS resistant TBC layer 58, a layer 60 containing a second TBC composition, and a second CMAS. Includes resistant TBC layer 62.

Although not shown in FIG. 4, in some embodiments, the multilayer TBC54 may include a binding layer 16 as described above with respect to FIGS. 1-3.

The first layer 56 and the second layer 60 have a structure similar to that previously described with respect to FIGS. 2 and 3 (layer 26 containing the TBC composition of FIG. 2 and first layer 36 and second of FIG. 3). It may be the same as the layer 40) of. Each of the first layer 56 and the second layer 60 can contain any combination of compositions and thicknesses previously described for similar layers in FIGS. 2 and 3. For example, the first layer 56 and the second layer 60 can each contain a thermal barrier coating composition. The compositions of the first layer 56 and the second layer 60 can be selected independently. In some embodiments, the first layer 56 has a composition similar to that of the second layer 60, while in other embodiments the first layer 56 differs from the second layer 60. Has a composition.

The first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 can each contain a composition similar to that previously described for the CMAS resistant TBC layer 18 of FIG. For example, at least one of the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 can include a TBC composition and a CMAS resistant composition.

The TBC composition of at least one of the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 is a TBC composition described herein, for example, yttria-stabilized zirconia, yttria-stabilized hafnia, at least 3. It can contain either zirconia stabilized with one rare earth oxide, or hafnia stabilized with at least three rare earth oxides. An example of a TBC composition suitable for use in the first CMAS resistant TBC layer 58 and / or the second CMAS resistant TBC layer 62 will be described earlier with respect to the CMAS resistant TBC layer 18 in FIG. There is.

The TBC composition in the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 can be selected independently. In some embodiments, at least one of the TBC compositions of the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 is the TBC composition in layer 56 containing the first TBC composition. And at least one of the TBC compositions in layer 60 containing the second TBC composition may be substantially similar. In other embodiments, the TBC composition of at least one of the first CMAS resistant TBC layer 58 or the second CMAS resistant TBC layer 62 is a layer 36 containing the first TBC composition and a second TBC composition. It may be different from the TBC composition in the layer 40 containing.

The first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 also contain a CMAS resistant composition. As described above for the CMAS resistant TBC layer 18 in FIG. 1, the CMAS resistant composition can include alumina, silica, and at least one rare earth oxide. In some embodiments, the CMAS resistant composition can comprise from about 1 mol% to about 99 mol% at least one rare earth oxide, as well as from about 1 mol% to about 99 mol% alumina and silica. In other embodiments, the CMAS resistant composition can include at least one rare earth oxide from about 10 mol% to about 90 mol%, as well as about 10 mol% to about 90 mol% alumina and silica. In other embodiments, the CMAS resistant composition can comprise from about 20 mol% to about 80 mol% at least one rare earth oxide, as well as from about 20 mol% to about 80 mol% alumina and silica.

Optionally, the CMAS resistant composition may further include additives such as TiO.₂, Ta₂O₅, HfSiO₄, Alkaline oxides, and alkaline earth oxides. In some embodiments, as described above, the additive is added to at least one of the CMAS resistant TBC layer 58 or the second CMAS resistant TBC layer 62 to give one or more properties of the CMAS resistant TBC layer 38. It can be fixed. In addition, the first CMAS resistant TBC layer 58 or the second CMAS resistant TBC layer 62 can include independently selected CMAS compositions that may be the same or different.

The first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 can each contain a mixture or alloy of the TBC composition and the CMAS resistant composition. For example, the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 can contain from about 1 wt% to about 99 wt% TBC composition and from about 1 wt% to about 99 wt% CMAS resistant composition. In some embodiments, at least one of the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 is about 50 wt% to about 90 wt% TBC composition and about 10 wt% to about 50 wt% CMAS. Contains resistant compositions. In other embodiments, at least one of the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 is about 50 wt% to about 70 wt% TBC composition and about 30 wt% to about 50 wt% CMAS resistant. Contains the composition.

The first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 can each include a substantially dense microstructure, a porous microstructure, or a columnar microstructure. The microstructures of the first CMAS resistant layer 58 and the second CMAS resistant TBC layer 62 can be independently selected and may be the same or different. The first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 can be deposited, for example, by plasma spraying, PVD, CVD, or slurry deposition, respectively. One of the PVDs that can be used to deposit at least one of the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 is EB-PVD. One of the EB-PVDs that can be used to deposit at least one of the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 is a DVD.

The first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62, respectively, shall be formed to any thickness suitable for the layers 58, 62 to provide the expected protection against the substrate 12. Can be done. In some embodiments, at least one of the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62 can be formed to a thickness of about 0.5 mils to about 20 mils.

In some embodiments, the multi-layered TBC 54, including the first CMAS resistant TBC layer 58 and the second CMAS resistant TBC layer 62, is additional to CMAS as compared to a coating containing only a single CMAS resistant TBC layer. Resistance can be provided. For example, the second CMAS resistant TBC layer 62 can provide initial protection from CMAS. In some embodiments, the second CMAS resistant TBC layer 62 can react with the CMAS present on the outer surface of the second CMAS resistant TBC layer 62 to form a reaction layer. The reaction layer can include a solid or highly viscous material that can reduce the reaction rate between CMAS and the second CMAS resistant TBC layer 62. That is, once a solid or highly viscous reaction layer occurs on the surface of the second CMAS resistant TBC layer 62, any further reaction will encounter the second CMAS resistant TBC layer 62 through the reaction layer. The reaction between the second CMAS resistant TBC layer 62 and CMAS is slowed down because it requires diffusion for the second CMAS resistant TBC layer 62 to encounter CMAS through the reaction layer. there is a possibility. In either case, when a solid or highly viscous reaction layer is formed on the surface of the second CMAS resistant TBC layer 62, either the CMAS or the components in the second CMAS resistant TBC layer 62 are diffused. However, it is expected to be the rate-determining step of the reaction.

Even if the reaction layer is not formed on the surface of the second CMAS resistant TBC layer 62 and / or sufficient time is sufficient to allow sufficient CMAS to react with the second CMAS resistant TBC layer 62. Even though the second CMAS resistant TBC layer 62 is consumed as a result, the first CMAS resistant TBC layer 58 (and, in some embodiments, the second layer 60) is described above with respect to FIG. As you can see, protection from CMAS can be provided for the first layer 56. In this manner, the second CMAS resistant TBC layer 62, the first CMAS resistant TBC layer 58, and optionally the second layer 60 are layered from the CMAS with respect to the first layer 56 and the substrate 12. Protection can be provided.

In addition or instead, in some embodiments, the multilayer TBC54 provides greater thermal protection for the substrate 12 compared to a thermal barrier coating containing only a single layer of comparable thickness. can do. As mentioned above, this is believed to be because the interface between the layers provides a scattering point for the phonons that transfer thermal energy through the coating 32.

In some embodiments, the concept of staggering a layer containing a TBC composition and a CMAS resistant TBC layer extends beyond the scope of a layer containing two TBC compositions and two CMAS resistant TBC layers. Can be done. For example, as shown in FIG. 5, article 70 includes layers 76a, 76b, 76c, 76d (collectively "Layer 76") containing four TBC compositions, and four CMAS resistant TBC layers 78a, 78b, 78c. , 78d (collectively "CMAS resistant TBC layer 78") can include a multi-layered TBC74. FIG. 5 shows an article containing four TBC compositions containing a layer 76 and four CMAS resistant TBC layers 78, where the article is a layer 76 containing any number of TBC compositions and any number of CMAS. A resistant TBC layer 78 can be included. In some embodiments, the article comprises a layer 76 and a CMAS resistant TBC layer 78 containing the same number of TBC compositions, while in other embodiments, the article has a different number than the CMAS resistant TBC layer 78. A layer 76 containing the TBC composition can be included. In embodiments where the article comprises a layer 76 containing a different number of TBC compositions than the CMAS resistant TBC layer 78, the article comprises a layer 76 containing a higher number of TBC compositions or a lower number of TBC compositions. A layer 76 containing the above can be included.

Each of the layers 76 can contain an independently selected TBC composition. Each of the TBC compositions can be selected from the TBC compositions disclosed herein.

In addition, each of the CMAS resistant TBC layers 78 can contain an independently selected composition. In some embodiments, at least two of the CMAS resistant TBC layers 78 can have the same composition. The compositions in the individual CMAS resistant TBC layers 78 can include any of the compositions previously described with respect to FIGS. 1-4, for example, a mixture or alloy of the TBC composition and the CMAS resistant composition.

In some embodiments, the top layer of the multilayer TBC74 is the CMAS resistant TBC layer 78d, as shown in FIG. However, in other embodiments, the top layer of the multilayer TBC74 may be a layer 76 containing the TBC composition.

In some embodiments, a multi-layered TBC 74 containing a plurality of CMAS resistant TBC layers 78 that are staggered with a layer 76 that contains the plurality of TBC compositions can provide advantages. For example, the multilayer TBC74 can provide greater thermal protection (eg, smaller effective thermal conductivity) than a coating containing a single layer of the same thickness as the multilayer TBC74. Although not desired to be constrained by theory, as mentioned above, the interface between different layers (eg, between layer 76a and CMAS resistant TBC layer 78a) has an interface between different layers. It provides a phonon scattering point that can reduce the thermal conductivity of the multilayer TBC74 compared to no coating. In some embodiments, the greater the number of alternating layers, the greater the reduction in thermal conductivity of the multilayer TBC74 can be provided. Additional or instead, the multilayer TBC74 is single because multiple CMAS resistant TBC layers 78 can provide multi-layer protection against penetration of CMAS into the pores or cracks of layer 76. Can provide improved CMAS resistance to substrate 12 as compared to coatings containing a CMAS resistant TBC layer.

Although various embodiments of the present disclosure have been described, these and other embodiments are included in the claims below.