Methods of protecting aerospace components against corrosion and oxidation

Embodiments of the present disclosure generally relate to protective coatings on an aerospace component and methods for depositing the protective coatings. In one or more embodiments, a method for depositing a coating on an aerospace component includes depositing one or more layers on a surface of the aerospace component using an atomic layer deposition or chemical vapor deposition process, and performing a partial oxidation and annealing process to convert the one or more layers to a coalesced layer having a preferred phase crystalline assembly. During oxidation cycles, an aluminum depleted region is formed at the surface of the aerospace component, and an aluminum oxide region is formed between the aluminum depleted region and the coalesced layer. The coalesced layer forms a protective coating, which decreases the rate of aluminum depletion from the aerospace component and the rate of new aluminum oxide scale formation.

BACKGROUND

Field

Embodiments of the present disclosure generally relate to deposition processes, and in particular to vapor deposition processes for depositing films on aerospace components.

Description of the Related Art

Turbine engines typically have components which corrode or degrade over time due to being exposed to hot gases and/or reactive chemicals (e.g., acids, bases, or salts). Such turbine components are often protected by a thermal and/or chemical barrier coating. The current coatings used on airfoils exposed to the hot gases of combustion in gas turbine engines for both environmental protection and as bond coats in thermal barrier coating (TBC) systems include both diffusion aluminides and various metal alloy coatings. These coatings are applied over substrate materials, typically nickel-based superalloys, to provide protection against oxidation and corrosion attack. These coatings are formed on the substrate in a number of different ways. For example, a nickel aluminide layer may be grown as an outer coat on a nickel base superalloy by simply exposing the substrate to an aluminum rich environment at elevated temperatures. The aluminum diffuses into the substrate and combines with the nickel to form an outer surface of the nickel-aluminum alloy.

A platinum modified nickel aluminide coating can be formed by first electroplating platinum to a predetermined thickness over the nickel-based substrate. Exposure of the platinum-plated substrate to an aluminum-rich environment at elevated temperatures causes the growth of an outer region of the nickel-aluminum alloy containing platinum in solid solution. In the presence of excess aluminum, the platinum-aluminum has two phases that may precipitate in the NiAl matrix as the aluminum diffuses into and reacts with the nickel and platinum.

However, as the increased demands for engine performance elevate the engine operating temperatures and/or the engine life requirements, improvements in the performance of coatings when used as environmental coatings or as bond coatings are needed over and above the capabilities of these existing coatings. Because of these demands, a coating that can be used for environmental protection or as a bond coat capable of withstanding higher operating temperatures or operating for a longer period of time before requiring removal for repair, or both, is desired. These known coating materials and deposition techniques have several shortcomings. Most metal alloy coatings deposited by low pressure plasma spray, plasma vapor deposition (PVD), electron beam PVD (EBPVD), cathodic arc, or similar sputtering techniques are line of sight coatings, meaning that interiors of components are not able to be coated. Platinum electroplating of exteriors typically forms a reasonably uniform coating, however, electroplating the interior of a component has proven to be challenging. The resulting electroplating coatings are often too thin to be protective or too thick that there are other adverse mechanical effects, such as high weight gain or fatigue life debit. Similarly, aluminide coatings suffer from non-uniformity on interior passages of components. Aluminide coatings are brittle, which can lead to reduced life when exposed to fatigue.

In addition, most of these coatings are on the order of greater than 10 micrometers in thickness, which can cause component weight to increase, making design of the disks and other support structures more challenging. It is desired by many to have coatings that (1) protect metals from oxidation and corrosion, (2) are capable of high film thickness and composition uniformity on arbitrary geometries, (3) have high adhesion to the metal, and/or (4) are sufficiently thin to not materially increase weight or reduce fatigue life outside of current design practices for bare metal.

Therefore, improved protective coatings and methods for depositing the protective coatings are needed.

SUMMARY

Embodiments of the present disclosure generally relate to protective coatings on an aerospace component and methods for depositing the protective coatings. In one or more embodiments, a method for depositing a coating on an aerospace component includes depositing one or more layers on a surface of the aerospace component using an atomic layer deposition or chemical vapor deposition process, and performing a partial oxidation and annealing process to convert the one or more layers to a coalesced layer having a preferred phase crystalline assembly. During oxidation cycles, an aluminum depleted region is formed at the surface of the aerospace component, and an aluminum oxide region is formed between the aluminum depleted region and the coalesced layer. The coalesced layer forms a protective coating, which decreases the rate of aluminum depletion from the aerospace component and the rate of new aluminum oxide scale formation.

In one embodiment, a method for depositing a coating on an aerospace component comprises exposing an aerospace component to a first precursor and a first reactant to form a first deposited layer on a surface of the aerospace component by a first atomic layer deposition process at a temperature between about 20 degrees Celsius to about 500 degrees Celsius, the aerospace component comprising nickel and aluminum. The first deposited layer forms a protective coating on the aerospace component. The protective coating protects the aerospace component from corrosion and oxidation and decreases a rate of depletion of aluminum from the aerospace component.

In another embodiment, a method for depositing a coating on an aerospace component comprises depositing a first deposited layer on a surface of an aerospace component by a chemical vapor deposition process, the aerospace component comprising nickel and aluminum, converting the first deposited layer to a crystalline phase, and forming an aluminum oxide region between the first deposited layer and the aerospace component, the aluminum oxide region having a crystalline assembly. The first deposited layer and the aluminum oxide region form a protective coating on the aerospace component. The protective coating protects the aerospace component from corrosion and oxidation and decreases a rate of depletion of aluminum from the aerospace component.

In yet another embodiment, a method for depositing a coating on an aerospace component comprises depositing a first deposited layer on a surface of an aerospace component by a chemical vapor deposition (CVD) process or an atomic layer deposition (ALD) process, the aerospace component comprising nickel and aluminum, performing a first annealing and oxidizing process to convert the first deposited layer into a preferred crystalline phase, depositing a second deposited layer by the CVD process or the ALD process on the first deposited layer, and performing a second annealing and oxidizing process to convert the second deposited layer into the preferred crystalline phase. The first deposited layer and the second deposited layer form a protective coating on the aerospace component. The protective coating protects the aerospace component from corrosion and oxidation and decreases a rate of depletion of aluminum from the aerospace component.

DETAILED DESCRIPTION

Embodiments of the present disclosure generally relate to protective coatings on an aerospace component and methods for depositing the protective coatings. In one or more embodiments, a method for depositing a coating on an aerospace component includes depositing one or more layers on a surface of the aerospace component using an atomic layer deposition or chemical vapor deposition process, and performing a partial oxidation and annealing process to convert the one or more layers to a coalesced layer having a preferred phase crystalline assembly. During oxidation cycles, an aluminum depleted region is formed at the surface of the aerospace component, and an aluminum oxide region is formed between the aluminum depleted region and the coalesced layer. The coalesced layer forms a protective coating, which decreases the rate of aluminum depletion from the aerospace component and the rate of new aluminum oxide scale formation.

In one or more embodiments, a method for depositing a protective coating on an aerospace component includes sequentially exposing the aerospace component to a chromium precursor and a reactant to form a chromium-containing layer on a surface the aerospace component by an atomic layer deposition (ALD) process. The chromium-containing layer contains metallic chromium, chromium oxide, chromium nitride, chromium carbide, chromium silicide, or any combination thereof.

In some embodiments, a nanolaminate film stack or protective coating is formed on the surface of the aerospace component, where the nanolaminate film stack or protective coating contains alternating layers of the chromium-containing layer and a second deposited layer. The aerospace component can be sequentially exposed to a metal or silicon precursor and a second reactant to form the second deposited layer on the surface by ALD. The second deposited layer contains aluminum oxide, hafnium doped aluminum oxide, aluminum nitride, silicon oxide, silicon nitride, silicon carbide, yttrium oxide, yttrium nitride, yttrium silicon nitride, hafnium oxide, hafnium nitride, hafnium silicide, hafnium silicate, titanium oxide, titanium nitride, titanium silicide, titanium silicate, or any combination thereof. The nanolaminate film stack or protective coating containing the alternating layers of the chromium-containing layer and the second deposited layer can be used as the protective coating on the aerospace component. Alternatively, in other embodiments, the nanolaminate film stack or protective coating disposed on the aerospace component can be exposed to an annealing process to convert the nanolaminate film stack or protective coating into a coalesced film, which can be used as the protective coating on the aerospace component.

FIG.1is a flow chart of a method100for depositing a coating on one or more aerospace components, according to one or more embodiments described and discussed herein.FIGS.2A-2B,FIGS.3A-3B,FIGS.4A-4B,FIGS.5A-5B, andFIGS.6A-6Bare various schematic examples of protective coatings disposed on a surface of the aerospace component, according to one or more embodiments described and discussed herein. The protective coatings ofFIGS.2A-6Bcan be deposited or otherwise formed on the aerospace component by the method100described and discussed below. Moreover, whileFIGS.2A-6Billustrate various embodiments, the embodiments depicted in each ofFIGS.2A-6Bmay be combined with one another. For description purposes,FIGS.2A-6Bwill be described prior to the method100.

FIG.2Aillustrates a protective coating200deposited on an aerospace component202. The aerospace component202comprises a nickel alloy comprising aluminum. The protective coating200comprises a first deposited layer204comprising aluminum, such as aluminum oxide (Al2O3). The first deposited layer204may be deposited in an amorphous or crystalline phase.FIG.2Billustrates the protective coating200ofFIG.2Aafter an optional annealing and oxidation process. For example, the optional annealing and oxidation process may be performed when the first deposited layer204is deposited in the amorphous phase. The oxidizing process may partially oxidize the protective coating200.

Following the optional annealing and oxidation process, the protective coating200comprises an intermediate region206disposed between the first deposited layer204and the aerospace component202. The intermediate region206is an aluminum depleted region of the aerospace component202, or a region depleted of an aluminum-rich phase. The intermediate region206may not be a distinct layer, but may instead be a topmost portion or region of the aerospace component202. Aluminum from the aerospace component202diffuses into the first deposited layer204, adding an additional amount of aluminum oxide (not shown) to the first deposited layer204. The additional amount of aluminum oxide and the first deposited layer204form a coalesced layer208having a preferred crystalline assembly. Thus, after the annealing process ofFIG.2B, the first deposited layer204has a greater amount of aluminum oxide. The protective coating200protects the aerospace component202from corrosion and oxidation, and further decreases the rate of depletion of aluminum from the intermediate region206. Performing the optional annealing and oxidizing process may further enhance and strengthen the protective properties of the protective coating200.

FIG.3Aillustrates a protective coating300or nanolaminate film stack deposited on an aerospace component302. The aerospace component302comprises a nickel alloy comprising aluminum. The protective component300comprises a first deposited layer310A comprising chromium, such as chromium oxide (Cr2O3). The first deposited layer310A may be deposited in an amorphous phase or a crystalline phase.FIG.3Billustrates the protective coating300ofFIG.3Aafter an optional annealing and oxidation process. For example, the optional annealing and oxidation process may be performed when the first deposited layer310A is deposited in the amorphous phase. The oxidizing process may partially oxidize the protective coating300. The protective coating300comprises a coalesced film or layer308formed during the annealing and oxidizing process, the coalesced layer308comprising a chromium oxide region310B from the first deposited layer310A. The coalesced layer308is in a preferred crystalline phase.

Following the annealing and oxidizing process, an intermediate region306is disposed between the coalesced layer308and the aerospace component302. The intermediate region306is an aluminum depleted region of the aerospace component302, or a region depleted of an aluminum-rich phase. The intermediate region306may not be a distinct layer, but may instead be a topmost portion or region of the aerospace component302. Aluminum from the aerospace component302diffuses into the coalesced layer308, forming a thin region314of aluminum oxide in the coalesced layer308above the intermediate region306. The coalesced layer308further comprises a mixed chromium-aluminum region312, such as chromium-aluminum oxide ((Al, Cr)2O3), disposed between the aluminum oxide region310and the chromium oxide region310B, each region being in a crystalline phase. While the regions310B,312,314of the coalesced layer308are shown as distinct regions or layers, the coalesced layer308is one, substantially continuous layer comprising each of the elements of the regions310B,312,314(i.e., aluminum oxide, chromium oxide, and mixed chromium-aluminum oxide). The protective coating300protects the aerospace component302from corrosion and oxidation, and further decreases the rate of depletion of aluminum from the intermediate region306. Performing the optional annealing and oxidizing process may further enhance and strengthen the protective properties of the protective coating300.

FIG.4Aillustrates a protective coating400or nanolaminate film stack deposited on an aerospace component402. The aerospace component402comprises a nickel alloy comprising aluminum. The protective component400comprises a first deposited layer404A comprising aluminum, such as aluminum oxide, and a second deposited layer410A comprising chromium, such as chromium oxide, disposed on the first deposited layer404A. The first deposited layer404A and the second deposited layer410A may each be deposited in an amorphous phase or a crystalline phase.FIG.4Billustrates the protective coating400ofFIG.4Aafter an optional annealing and oxidation process. For example, the optional annealing and oxidation process may be performed when the first deposited layer404A and/or the second deposited layer410A are deposited in the amorphous phase. The oxidizing process may partially oxidize the protective coating400. The protective coating400includes a coalesced film or layer408formed during the annealing and oxidizing process, the coalesced layer408comprising an aluminum oxide region404B from the first deposited layer404A and a chromium oxide region410B from the second deposited layer410A. The coalesced layer408is in a preferred crystalline phase.

In one embodiment, the first deposited layer404A may be deposited, and then annealed and oxidized to convert the first deposited layer404A to the preferred crystalline phase. The second deposited layer410A may then be deposited on the first deposited layer404A, and then annealed and oxidized to convert the second deposited layer410A to the preferred crystalline phase.

Following the annealing and oxidizing process, an intermediate region406is disposed between the coalesced layer408and the aerospace component402. The intermediate region406is an aluminum depleted region of the aerospace component402, or a region depleted of an aluminum-rich phase. The intermediate region406may not be a distinct layer, but may instead be a topmost portion or region of the aerospace component402. Aluminum from the aerospace component402diffuses into the coalesced layer408, adding an additional amount of aluminum oxide to the aluminum oxide region404B of the coalesced layer408above the intermediate region406. The coalesced layer408further comprises a mixed chromium-aluminum region412, such as chromium-aluminum oxide, disposed between the aluminum oxide region404B and the chromium oxide region410B, each region being in a crystalline phase. While the regions404B,412,410B of the coalesced layer408are shown as distinct regions or layers, the coalesced layer408is one, substantially continuous layer comprising each of the elements of the regions404B,412,410B (i.e., aluminum oxide, chromium oxide, and mixed chromium-aluminum oxide). The protective coating400protects the aerospace component402from corrosion and oxidation, and further decreases the rate of depletion of aluminum from the intermediate region406. Performing the optional annealing and oxidizing process may further enhance and strengthen the protective properties of the protective coating400.

FIG.5Aillustrates a protective coating500or nanolaminate film stack deposited on an aerospace component502. The aerospace component502comprises a nickel alloy comprising aluminum. The protective component500comprises a first deposited layer504A comprising aluminum (e.g., aluminum oxide), a second deposited layer516comprising chromium (e.g., chromium oxide) disposed on the first deposited layer504A, a third deposited layer518comprising aluminum (e.g., aluminum oxide) disposed on the second deposited layer516, a fourth deposited layer520comprising chromium (e.g., chromium oxide) disposed on the third deposited layer518, and a fifth deposited layer522comprising aluminum (e.g., aluminum oxide) disposed on the fourth deposited layer520. Each of the deposited layers504A,516,518,520,522may be deposited in an amorphous phase or a crystalline phase. The first deposited layer504A may have a greater thickness than each of the second through fifth deposited layers516-522. The second through fifth deposited layers516-522may have about the same thickness. While five deposited layers are shown, any number of layers may be utilized.

FIG.5Billustrates the protective component500ofFIG.5Aafter an optional annealing and oxidation process. For example, the optional annealing and oxidation process may be performed when one or more of the deposited layers504A,516,518,520,522are deposited in the amorphous phase. The oxidizing process may partially oxidize the protective coating500. In one embodiment, the first deposited layer504A may be deposited, and then annealed and oxidized to convert the first deposited layer504A to the preferred crystalline phase. The second deposited layer516may then be deposited on the first deposited layer504A, and then annealed and oxidized to convert the second deposited layer516to the preferred crystalline phase. The third deposited layer518may then be deposited on the second deposited layer516, and then annealed and oxidized to convert the third deposited layer518to the preferred crystalline phase. The fourth deposited layer520may then be deposited on the third deposited layer518, and then annealed and oxidized to convert the fourth deposited layer520to the preferred crystalline phase. The fifth deposited layer522may then be deposited on the fourth deposited layer520, and then annealed and oxidized to convert the fifth deposited layer522to the preferred crystalline phase.

The protective coating500comprises a coalesced film or layer508formed during the annealing and oxidizing process, the coalesced layer508comprising an aluminum oxide region504B from the first deposited layer504A and a mixed chromium-aluminum region512, such as chromium-aluminum oxide. The coalesced layer508is in a preferred crystalline phase. An intermediate region506is disposed between the coalesced layer508and the aerospace component502. The intermediate region506is an aluminum depleted region of the aerospace component502, or a region depleted of an aluminum-rich phase. The intermediate region506may not be a distinct layer, but may instead be a topmost portion or region of the aerospace component502. Aluminum from the aerospace component502diffuses into the coalesced layer508, adding an additional amount of aluminum oxide to the aluminum oxide region504B of the coalesced layer508above the intermediate region506. While the regions504B and512of the coalesced layer508are shown as distinct regions or layers, the coalesced layer508is one, substantially continuous layer comprising each of the elements of the regions504B,512(i.e., aluminum oxide, and mixed chromium-aluminum oxide). The protective coating500protects the aerospace component502from corrosion and oxidation, and further decreases the rate of depletion of aluminum from the intermediate region506. Performing the optional annealing and oxidizing process may further enhance and strengthen the protective properties of the protective coating500.

FIG.6Aillustrates a protective coating600or nanolaminate film stack deposited on an aerospace component602. The aerospace component602comprises a nickel alloy comprising aluminum. The protective component600comprises a first deposited layer624comprising hafnium (e.g., hafnium doped aluminum oxide), a second deposited layer616comprising chromium (e.g., chromium oxide) disposed on the first deposited layer624, a third deposited layer618comprising aluminum (e.g., aluminum oxide) disposed on the second deposited layer616, a fourth deposited layer620comprising chromium (e.g., chromium oxide) disposed on the third deposited layer618, and a fifth deposited layer622comprising aluminum (e.g., aluminum oxide) disposed on the fourth deposited layer620. Each of the deposited layers624,616,618,620,622may be deposited in an amorphous phase or a crystalline phase. The first deposited layer624may have a greater thickness than each of the second through fifth deposited layers616-622. The second through fifth deposited layers616-622may have about the same thickness. While five deposited layers are shown, any number of layers may be utilized.

FIG.6Billustrates the protective coating600ofFIG.6Aafter an optional annealing and oxidation process. For example, the optional annealing and oxidation process may be performed when one or more of the deposited layers624,616,618,620,622are deposited in the amorphous phase. The oxidizing process may partially oxidize the protective coating600. In one embodiment, the first deposited layer624may be deposited, and then annealed and oxidized to convert the first deposited layer624to the preferred crystalline phase. The second deposited layer616may then be deposited on the first deposited layer624, and then annealed and oxidized to convert the second deposited layer616to the preferred crystalline phase. The third deposited layer618may then be deposited on the second deposited layer616, and then annealed and oxidized to convert the third deposited layer618to the preferred crystalline phase. The fourth deposited layer620may then be deposited on the third deposited layer618, and then annealed and oxidized to convert the fourth deposited layer620to the preferred crystalline phase. The fifth deposited layer622may then be deposited on the fourth deposited layer620, and then annealed and oxidized to convert the fifth deposited layer622to the preferred crystalline phase.

The protective coating600comprises a coalesced film or layer608formed during the annealing and oxidizing process disposed on the first deposited layer624, the coalesced layer608comprising a mixed chromium-aluminum compound, such as chromium-aluminum oxide. The coalesced layer608is in a preferred crystalline phase. An intermediate region606is disposed between the coalesced layer608and the aerospace component602. The intermediate region606is an aluminum depleted region of the aerospace component602, or a region depleted of an aluminum-rich phase. The intermediate region606may not be a distinct layer, but may instead be a topmost portion or region of the aerospace component602. Aluminum from the aerospace component602diffuses into the first deposited layer624, adding an additional amount of aluminum oxide to the first deposited layer624above the intermediate region606. The protective coating600protects the aerospace component602from corrosion and oxidation, and further decreases the rate of depletion of aluminum from the intermediate region606. Performing the optional annealing and oxidizing process may further enhance and strengthen the protective properties of the protective coating600.

At block110, prior to producing a protective coating200,300,400,500,600, the aerospace component202,302,402,502,602can optionally be exposed to one or more pre-clean processes. The surfaces of the aerospace component202,302,402,502,602can contain oxides, organics, oil, soil, particulate, debris, and/or other contaminants that may be removed prior to producing the protective coating200,300,400,500,600on the aerospace component202,302,402,502,602. The pre-clean process can be or include one or more basting or texturing processes, vacuum purges, solvent clean, acid clean, wet clean, plasma clean, sonication, or any combination thereof. Once cleaned and/or textured, the subsequently deposited protective coating200,300,400,500,600has stronger adhesion to the surfaces of the aerospace component202,302,402,502,602than if otherwise not exposed to the pre-clean process.

In one or more examples, the surfaces of the aerospace component202,302,402,502,602can be blasted with or otherwise exposed to beads, sand, carbonate, or other particulates to remove oxides and other contaminates therefrom and/or to provide texturing to the surfaces of the aerospace component202,302,402,502,602. In some examples, the aerospace component202,302,402,502,602can be placed into a chamber within a pulsed push-pull system and exposed to cycles of purge gas (e.g., N2, Ar, He, or any combination thereof) and vacuum purges to remove debris from small holes on the aerospace component202,302,402,502,602. In other examples, the surfaces of the aerospace component202,302,402,502,602can be exposed to hydrogen plasma, oxygen or ozone plasma, and/or nitrogen plasma, which can be generated in a plasma chamber or by a remote plasma system.

In one or more examples, such as for organic removal or oxide removal, the surfaces of the aerospace component202,302,402,502,602can be exposed to a hydrogen plasma, then degassed, then exposed to ozone treatment. In other examples, such as for organic removal, the surfaces of the aerospace component202,302,402,502,602can be exposed to a wet clean that includes: soaking in an alkaline degreasing solution, rinsing, exposing the surfaces to an acid clean (e.g., sulfuric acid, phosphoric acid, or hydrochloric acid), rinsing, and exposing the surfaces deionized water sonication bath. In some examples, such as for oxide removal, the surfaces of the aerospace component202,302,402,502,602can be exposed to a wet clean that includes: exposing the surfaces to a dilute acid solution (e.g., acetic acid or hydrochloric acid), rinsing, and exposing the surfaces deionized water sonication bath. In one or more examples, such as for particle removal, the surfaces of the aerospace component202,302,402,502,602can be exposed to sonication (e.g., megasonication) and/or a supercritical carbon dioxide wash, followed by exposing to cycles of purge gas (e.g., N2, Ar, He, or any combination thereof) and vacuum purges to remove particles from and dry the surfaces. In some examples, the aerospace component202,302,402,502,602can be exposed to heating or drying processes, such as heating the aerospace component202,302,402,502,602to a temperature of about 50° C., about 65° C., or about 80° C. to about 100° C., about 120° C., or about 150° C. and exposing to surfaces to the purge gas. The aerospace component202,302,402,502,602can be heated in an oven or exposed to lamps for the heating or drying processes.

At block120, the aerospace component202,302,402,502, or602is exposed to a first precursor and a first reactant to form the first deposited layer204,310A,404A,504A, or624on the aerospace component202,302,402,502,602by a vapor deposition process, as depicted inFIGS.2A,3A,4A,5A, and6A, respectively, to form a protective coating200,300,400,500,600. The vapor deposition process can be an ALD process, a plasma-enhanced ALD (PE-ALD) process, a thermal chemical vapor deposition (CVD) process, a plasma-enhanced CVD (PE-CVD) process, a low pressure CVD process, or any combination thereof.

In one or more embodiments, the vapor deposition process is an ALD process and the method includes sequentially exposing the surface of the aerospace component202,302,402,502, or602to the first precursor and the first reactant to form the first deposited layer204,310A,404A,504A, or624. Each cycle of the ALD process includes exposing the surface of the aerospace component to the first precursor, conducting a pump-purge, exposing the aerospace component to the first reactant, and conducting a pump-purge to form the first deposited layer204,310A,404A,504A, or624. The order of the first precursor and the first reactant can be reversed, such that the ALD cycle includes exposing the surface of the aerospace component to the first reactant, conducting a pump-purge, exposing the aerospace component to the first precursor, and conducting a pump-purge to form the first deposited layer204,310A,404A,504A, or624.

In some examples, during each ALD cycle, the aerospace component202,302,402,502,602is exposed to the first precursor for about 0.1 seconds to about 10 seconds, the first reactant for about 0.1 seconds to about 10 seconds, and the pump-purge for about 0.5 seconds to about 30 seconds. In other examples, during each ALD cycle, the aerospace component202,302,402,502,602is exposed to the first precursor for about 0.5 seconds to about 3 seconds, the first reactant for about 0.5 seconds to about 3 seconds, and the pump-purge for about 1 second to about 10 seconds. The ALD process may be performed at a temperature of about 20° C. to about 500° C., such as about 300° C.

Each ALD cycle is repeated from 2, 3, 4, 5, 6, 8, about 10, about 12, or about 15 times to about 18, about 20, about 25, about 30, about 40, about 50, about 65, about 80, about 100, about 120, about 150, about 200, about 250, about 300, about 350, about 400, about 500, about 800, about 1,000, or more times to form the first deposited layer. For example, each ALD cycle is repeated from 2 times to about 1,000 times, 2 times to about 800 times, 2 times to about 500 times, 2 times to about 300 times, 2 times to about 250 times, 2 times to about 200 times, 2 times to about 150 times, 2 times to about 120 times, 2 times to about 100 times, 2 times to about 80 times, 2 times to about 50 times, 2 times to about 30 times, 2 times to about 20 times, 2 times to about 15 times, 2 times to about 10 times, 2 times to 5 times, about 8 times to about 1,000 times, about 8 times to about 800 times, about 8 times to about 500 times, about 8 times to about 300 times, about 8 times to about 250 times, about 8 times to about 200 times, about 8 times to about 150 times, about 8 times to about 120 times, about 8 times to about 100 times, about 8 times to about 80 times, about 8 times to about 50 times, about 8 times to about 30 times, about 8 times to about 20 times, about 8 times to about 15 times, about 8 times to about 10 times, about 20 times to about 1,000 times, about 20 times to about 800 times, about 20 times to about 500 times, about 20 times to about 300 times, about 20 times to about 250 times, about 20 times to about 200 times, about 20 times to about 150 times, about 20 times to about 120 times, about 20 times to about 100 times, about 20 times to about 80 times, about 20 times to about 50 times, about 20 times to about 30 times, about 50 times to about 1,000 times, about 50 times to about 500 times, about 50 times to about 350 times, about 50 times to about 300 times, about 50 times to about 250 times, about 50 times to about 150 times, or about 50 times to about 100 times to form the first deposited layer204,310A,404A,504A, or624.

In other embodiments, the vapor deposition process is a CVD process and the method includes simultaneously exposing the aerospace component202,302,402,502, or602to the first precursor and the first reactant to form the first deposited layer204,310A,404A,504A,624. The CVD process may be performed at a temperature of about 300° C. to about 1200° C. The CVD process may be performed at a higher temperature than the ALD process. For example, the ALD process may be performed at a temperature of about 500° C. and the CVD process may be performed at a temperature of about 1100° C. The CVD process may be a PECVD process performed at a temperature of about 300° C. to about 1100° C., a low pressure CVD process performed at a temperature of about 500° C. to about 1100° C., or a thermal CVD process performed at a temperature of about 500° C. to about 1100° C. Depositing the first deposited layer204,310A,404A,504A,624by a CVD process may convert the first deposited layer204,310A,404A,504A,624to a crystalline phase. As such, the protective coating200,300,400,500,600may not need to undergo the annealing and oxidation process. However, the first deposited layer204,310A,404A,504A,624deposited through a CVD process may need to undergo the annealing and oxidation process to convert the first deposited layer204,310A,404A,504A,624to the preferred crystalline assembly.

During an ALD process or a CVD process, each of the first precursor and the first reactant can independent include one or more carrier gases. One or more purge gases can be flowed across the aerospace component and/or throughout the processing chamber in between the exposures of the first precursor and the first reactant. In some examples, the same gas may be used as a carrier gas and a purge gas. Exemplary carrier gases and purge gases can independently be or include one or more of nitrogen (N2), argon, helium, neon, hydrogen (H2), or any combination thereof.

The first deposited layer204,310A,404A,504A, or624can have a thickness of about 0.1 nm, about 0.2 nm, about 0.3 nm, about 0.4 nm, about 0.5 nm, about 0.8 nm, about 1 nm, about 2 nm, about 3 nm, about 5 nm, about 8 nm, about 10 nm, about 12 nm, or about 15 nm to about 18 nm, about 20 nm, about 25 nm, about 30 nm, about 40 nm, about 50 nm, about 60 nm, about 80 nm, about 100 nm, about 120 nm, or about 150 nm. For example, the first deposited layer204,310A,404A,504A, or624can have a thickness of about 0.1 nm to about 150 nm, about 0.2 nm to about 150 nm, about 0.2 nm to about 120 nm, about 0.2 nm to about 100 nm, about 0.2 nm to about 80 nm, about 0.2 nm to about 50 nm, about 0.2 nm to about 40 nm, about 0.2 nm to about 30 nm, about 0.2 nm to about 20 nm, about 0.2 nm to about 10 nm, about 0.2 nm to about 5 nm, about 0.2 nm to about 1 nm, about 0.2 nm to about 0.5 nm, about 0.5 nm to about 150 nm, about 0.5 nm to about 120 nm, about 0.5 nm to about 100 nm, about 0.5 nm to about 80 nm, about 0.5 nm to about 50 nm, about 0.5 nm to about 40 nm, about 0.5 nm to about 30 nm, about 0.5 nm to about 20 nm, about 0.5 nm to about 10 nm, about 0.5 nm to about 5 nm, about 0.5 nm to about 1 nm, about 2 nm to about 150 nm, about 2 nm to about 120 nm, about 2 nm to about 100 nm, about 2 nm to about 80 nm, about 2 nm to about 50 nm, about 2 nm to about 40 nm, about 2 nm to about 30 nm, about 2 nm to about 20 nm, about 2 nm to about 10 nm, about 2 nm to about 5 nm, about 2 nm to about 3 nm, about 10 nm to about 150 nm, about 10 nm to about 120 nm, about 10 nm to about 100 nm, about 10 nm to about 80 nm, about 10 nm to about 50 nm, about 10 nm to about 40 nm, about 10 nm to about 30 nm, about 10 nm to about 20 nm, or about 10 nm to about 15 nm.

In one or more embodiments, the first precursor contains one or more chromium precursors, such as inFIG.3A, one or more aluminum precursors, such as inFIGS.2A,4A, and5A, or one or more hafnium precursors, such as inFIG.6A. The first reactant contains one or more reducing agents, one or more oxidizing agents, one or more nitriding agents, one or more silicon precursors, one or more carbon precursors, or any combination thereof. In some examples, such asFIG.3A, the first deposited layer310A is a chromium-containing layer which can be or include metallic chromium, chromium oxide, chromium nitride, chromium silicide, chromium carbide, or any combination thereof. In other examples, such asFIGS.2A,4A,5A, and6A, the first deposited layer204,404A,504A, or624is an aluminum-containing layer which can be or include metallic aluminum, aluminum oxide, aluminum nitride, aluminum silicide, aluminum carbide, or any combination thereof. In further examples, such asFIG.6A, the first deposited layer624is a hafnium-containing layer which can be or include hafnium doped aluminum oxide, metallic hafnium, hafnium oxide, hafnium nitride, hafnium silicide, hafnium carbide, or any combination thereof.

where each R and R′ is independently selected from H, C1-C6 alkyl, aryl, acyl, alkylamido, hydrazido, silyl, aldehyde, keto, C2-C4 alkenyl, alkynyl, or substitutes thereof. In some examples, each R is independently a C1-C6 alkyl which is selected from methyl, ethyl, propyl, butyl, or isomers thereof, and R′ is H. For example, R is metyl and R′ is H, R is ethyl and R′ is H, R is iso-propyl and R′ is H, or R is tert-butyl and R′ is H.

The aluminum precursor can be or include one or more of aluminum alkyl compounds, one or more of aluminum alkoxy compounds, one or more of aluminum acetylacetonate compounds, substitutes thereof, complexes thereof, abducts thereof, salts thereof, or any combination thereof. Exemplary aluminum precursors can be or include trimethylaluminum, triethylaluminum, tripropylaluminum, tributylaluminum, trimethoxyaluminum, triethoxyaluminum, tripropoxyaluminum, tributoxyaluminum, aluminum acetylacetonate (Al(acac)3, also known as, tris(2,4-pentanediono) aluminum), aluminum hexafluoroacetylacetonate (Al(hfac)3), trisdipivaloylmethanatoaluminum (DPM3Al; (C11H19O2)3Al), isomers thereof, complexes thereof, abducts thereof, salts thereof, or any combination thereof.

The titanium precursor can be or include one or more of titanium cyclopentadiene compounds, one or more of titanium amino compounds, one or more of titanium alkyl compounds, one or more of titanium alkoxy compounds, substitutes thereof, complexes thereof, abducts thereof, salts thereof, or any combination thereof. Exemplary titanium precursors can be or include bis(methylcyclopentadiene) dimethyltitanium ((MeCp)2TiMe2), bis(methylcyclopentadiene) methylmethoxytitanium ((MeCp)2Ti(OMe)(Me)), bis(cyclopentadiene) dimethyltitanium ((Cp)2TiMe2), tetra(tert-butoxy) titanium, titaniumum isopropoxide ((iPrO)4Ti), tetrakis(dimethylamino) titanium (TDMAT), tetrakis(diethylamino) titanium (TDEAT), tetrakis(ethylmethylamino) titanium (TEMAT), isomers thereof, complexes thereof, abducts thereof, salts thereof, or any combination thereof.

In one or more examples, the first deposited layer310A is a chromium-containing layer which can be or include metallic chromium and the first reactant contains one or more reducing agents. In some examples, the first deposited layer204,404A,504A, or624is an aluminum-containing layer which can be or include metallic aluminum and the first reactant contains one or more reducing agents. In other examples, the first deposited layer624is a hafnium-containing layer which can be or include metallic hafnium and the first reactant contains one or more reducing agents. Exemplary reducing agents can be or include hydrogen (H2), ammonia, hydrazine, one or more hydrazine compounds, one or more alcohols, a cyclohexadiene, a dihydropyrazine, an aluminum containing compound, abducts thereof, salts thereof, plasma derivatives thereof, or any combination thereof.

In some examples, the first deposited layer310A is a chromium-containing layer which can be or include chromium oxide and the first reactant contains one or more oxidizing agents. In other examples, the first deposited layer204,404A,504A, or624is an aluminum-containing layer which can be or include aluminum oxide and the first reactant contains one or more oxidizing agents. In further examples, the first deposited layer624is a hafnium-containing layer which can be or include hafnium oxide and the first reactant contains one or more oxidizing agents. Exemplary oxidizing agents can be or include water (e.g., steam), oxygen (O2), atomic oxygen, ozone, nitrous oxide, one or more peroxides, one or more alcohols, plasmas thereof, or any combination thereof.

In one or more examples, the first deposited layer310A is a chromium-containing layer which can be or include chromium nitride and the first reactant contains one or more nitriding agents. In other examples, the first deposited layer204,404A,504A, or624is an aluminum-containing layer which can be or include aluminum nitride and the first reactant contains one or more nitriding agents. In some examples, the first deposited layer624is a hafnium-containing layer which can be or include hafnium nitride and the first reactant contains one or more nitriding agents. Exemplary nitriding agents can be or include ammonia, atomic nitrogen, one or more hydrazines, nitric oxide, plasmas thereof, or any combination thereof.

In one or more examples, the first deposited layer310A is a chromium-containing layer which can be or include chromium silicide and the first reactant contains one or more silicon precursors. In some examples, the first deposited layer204,404A,504A, or624is an aluminum-containing layer which can be or include aluminum silicide and the first reactant contains one or more silicon precursors. In other examples, the first deposited layer624is a hafnium-containing layer which can be or include hafnium silicide and the first reactant contains one or more silicon precursors. Exemplary silicon precursors can be or include silane, disilane, trisilane, tetrasilane, pentasilane, hexasilane, monochlorosilane, dichlorosilane, trichlorosilane, tetrachlorosilane, hexachlorosilane, substituted silanes, plasma derivatives thereof, or any combination thereof.

In some examples, the first deposited layer310A is a chromium-containing layer which can be or include chromium carbide and the first reactant contains one or more carbon precursors. In other examples, the first deposited layer204,404A,504A, or624is an aluminum-containing layer which can be or include aluminum carbide and the first reactant contains one or more carbon precursors. In further examples, the first deposited layer624is a hafnium-containing layer which can be or include hafnium carbide and the first reactant contains one or more carbon precursors. Exemplary carbon precursors can be or include one or more alkanes, one or more alkenes, one or more alkynes, substitutes thereof, plasmas thereof, or any combination thereof.

At block130, the aerospace component402,502,602is optionally exposed to a second precursor and a second reactant to form the second deposited layer410A,516, or616on the first deposited layer404A,504A, or624to add to the protective coating400,500,600, as shown inFIGS.4A,5A, and6A. The first deposited layer404A,504A, or624orFIGS.4A,5A, and6Aand second deposited layer410A,516,616orFIGS.4A,5A, and6A, respectively, have different compositions from each other. In some examples, the first precursor is a different precursor than the second precursor, such as that the first precursor is a source of a first type of metal and the second precursor is a source of a second type of metal and the first and second types of metal are different. WhileFIG.2AandFIG.3Aare not shown with a second deposited layer, the protective coatings200,300may include one or more second deposited layers having a different composition than the first deposited layers204,310A.

In one or more embodiments, the second precursor is or includes one or more aluminum precursors or one or more chromium precursors; however, the second precursor can be or include one or more aluminum precursors, one or more chromium precursors, one or more hafnium precursors, one or more yttrium precursors, or any combination thereof. The second reactant can be any other reactants used as the first reactant. For example, the second reactant can be or include one or more reducing agents, one or more oxidizing agents, one or more nitriding agents, one or more silicon precursors, one or more carbon precursors, or any combination thereof, as described and discussed above. During the ALD process, each of the second precursor and the second reactant can independent include one or more carrier gases. One or more purge gases can be flowed across the aerospace component and/or throughout the processing chamber in between the exposures of the second precursor and the second reactant. In some examples, the same gas may be used as a carrier gas and a purge gas. Exemplary carrier gases and purge gases can independently be or include one or more of nitrogen (N2), argon, helium, neon, hydrogen (H2), or any combination thereof.

In one or more embodiments, the second deposited layer410A,516,616contains chromium oxide or aluminum oxide; however, the second deposited layer410A,516,616may contain aluminum nitride, silicon oxide, silicon nitride, silicon carbide, yttrium oxide, yttrium nitride, yttrium silicon nitride, hafnium oxide, hafnium nitride, hafnium silicide, hafnium silicate, titanium oxide, titanium nitride, titanium silicide, titanium silicate, or any combination thereof. In one or more examples, if the first deposited layer204,310A,404A,504A, or624contains aluminum oxide or aluminum nitride, then the second deposited layer410A,516,616does not contain aluminum oxide or aluminum nitride. Similarly, if the first deposited layer204,310A,404A,504A, or624contains chromium oxide or chromium nitride, then the second deposited layer410A,516,616does not contain chromium oxide or chromium nitride. If the first deposited layer204,310A,404A,504A, or624contains hafnium oxide or hafnium nitride, then the second deposited layer410A,516,616does not contain hafnium oxide or hafnium nitride.

Each cycle of the ALD process includes exposing the aerospace component to the second precursor, conducting a pump-purge, exposing the aerospace component to the second reactant, and conducting a pump-purge to form the second deposited layer410A,516,616. The order of the second precursor and the second reactant can be reversed, such that the ALD cycle includes exposing the surface of the aerospace component to the second reactant, conducting a pump-purge, exposing the aerospace component to the second precursor, and conducting a pump-purge to form the second deposited layer410A,516,616.

In one or more examples, during each ALD cycle, the aerospace component402,502,602is exposed to the second precursor for about 0.1 seconds to about 10 seconds, the second reactant for about 0.1 seconds to about 10 seconds, and the pump-purge for about 0.5 seconds to about 30 seconds. In other examples, during each ALD cycle, the aerospace component402,502,602is exposed to the second precursor for about 0.5 seconds to about 3 seconds, the second reactant for about 0.5 seconds to about 3 seconds, and the pump-purge for about 1 second to about 10 seconds. The ALD process may be performed at a temperature of about 20° C. to about 500° C., such as about 300° C.

Each ALD cycle is repeated from 2, 3, 4, 5, 6, 8, about 10, about 12, or about 15 times to about 18, about 20, about 25, about 30, about 40, about 50, about 65, about 80, about 100, about 120, about 150, about 200, about 250, about 300, about 350, about 400, about 500, about 800, about 1,000, or more times to form the second deposited layer410A,516,616. For example, each ALD cycle is repeated from 2 times to about 1,000 times, 2 times to about 800 times, 2 times to about 500 times, 2 times to about 300 times, 2 times to about 250 times, 2 times to about 200 times, 2 times to about 150 times, 2 times to about 120 times, 2 times to about 100 times, 2 times to about 80 times, 2 times to about 50 times, 2 times to about 30 times, 2 times to about 20 times, 2 times to about 15 times, 2 times to about 10 times, 2 times to 5 times, about 8 times to about 1,000 times, about 8 times to about 800 times, about 8 times to about 500 times, about 8 times to about 300 times, about 8 times to about 250 times, about 8 times to about 200 times, about 8 times to about 150 times, about 8 times to about 120 times, about 8 times to about 100 times, about 8 times to about 80 times, about 8 times to about 50 times, about 8 times to about 30 times, about 8 times to about 20 times, about 8 times to about 15 times, about 8 times to about 10 times, about 20 times to about 1,000 times, about 20 times to about 800 times, about 20 times to about 500 times, about 20 times to about 300 times, about 20 times to about 250 times, about 20 times to about 200 times, about 20 times to about 150 times, about 20 times to about 120 times, about 20 times to about 100 times, about 20 times to about 80 times, about 20 times to about 50 times, about 20 times to about 30 times, about 50 times to about 1,000 times, about 50 times to about 500 times, about 50 times to about 350 times, about 50 times to about 300 times, about 50 times to about 250 times, about 50 times to about 150 times, or about 50 times to about 100 times to form the second deposited layer410A,516,616.

The second deposited layer410A,516,616can have a thickness of about 0.1 nm, about 0.2 nm, about 0.3 nm, about 0.4 nm, about 0.5 nm, about 0.8 nm, about 1 nm, about 2 nm, about 3 nm, about 5 nm, about 8 nm, about 10 nm, about 12 nm, or about 15 nm to about 18 nm, about 20 nm, about 25 nm, about 30 nm, about 40 nm, about 50 nm, about 60 nm, about 80 nm, about 100 nm, about 120 nm, or about 150 nm. For example, the second deposited layer410A,516,616can have a thickness of about 0.1 nm to about 150 nm, about 0.2 nm to about 150 nm, about 0.2 nm to about 120 nm, about 0.2 nm to about 100 nm, about 0.2 nm to about 80 nm, about 0.2 nm to about 50 nm, about 0.2 nm to about 40 nm, about 0.2 nm to about 30 nm, about 0.2 nm to about 20 nm, about 0.2 nm to about 10 nm, about 0.2 nm to about 5 nm, about 0.2 nm to about 1 nm, about 0.2 nm to about 0.5 nm, about 0.5 nm to about 150 nm, about 0.5 nm to about 120 nm, about 0.5 nm to about 100 nm, about 0.5 nm to about 80 nm, about 0.5 nm to about 50 nm, about 0.5 nm to about 40 nm, about 0.5 nm to about 30 nm, about 0.5 nm to about 20 nm, about 0.5 nm to about 10 nm, about 0.5 nm to about 5 nm, about 0.5 nm to about 1 nm, about 2 nm to about 150 nm, about 2 nm to about 120 nm, about 2 nm to about 100 nm, about 2 nm to about 80 nm, about 2 nm to about 50 nm, about 2 nm to about 40 nm, about 2 nm to about 30 nm, about 2 nm to about 20 nm, about 2 nm to about 10 nm, about 2 nm to about 5 nm, about 2 nm to about 3 nm, about 10 nm to about 150 nm, about 10 nm to about 120 nm, about 10 nm to about 100 nm, about 10 nm to about 80 nm, about 10 nm to about 50 nm, about 10 nm to about 40 nm, about 10 nm to about 30 nm, about 10 nm to about 20 nm, or about 10 nm to about 15 nm.

In some examples, such asFIG.4A, the first deposited layer410A is a chromium-containing layer that contains chromium oxide, chromium nitride, or a combination thereof, and the second deposited layer410A contains one or more of aluminum oxide, silicon nitride, hafnium oxide, hafnium silicate, titanium oxide, or any combination thereof.

The second deposited layer410A,516,616may be deposited using a CVD process. The CVD process may be performed at a temperature of about 300° C. to about 1200° C. The CVD process may be performed at a higher temperature than the ALD process. For example, the ALD process may be performed at a temperature of about 500° C. and the CVD process may be performed at a temperature of about 1100° C. The CVD process may be a PECVD process performed at a temperature of about 300° C. to about 1100° C., a low pressure CVD process performed at a temperature of about 500° C. to about 1100° C., or a thermal CVD process performed at a temperature of about 500° C. to about 1100° C. Depositing the second deposited layer410A,516,616by a CVD process may convert the second deposited layer410A,516,616to a crystalline phase. As such, the protective coating200,300,400,500,600may not need to undergo the annealing and oxidation process. However, the second deposited layer410A,516,616deposited through a CVD process may need to undergo the annealing and oxidation process to convert the second deposited layer410A,516,616to the preferred crystalline assembly.

At block140, the aerospace component602is optionally exposed to a third precursor and a third reactant to form the third deposited layer618on the second deposited layer616to add to the protective coating600, such as shown inFIG.6A. The first deposited layer624, the second deposited layer616, and the third deposited layer618each have different compositions from each other. In some examples, the third precursor is a different precursor than the first and second precursors. The third deposited layer618may have the same thickness as the second deposited layer616. Additionally, the third deposited layer618may be formed in the same process or manner as the second deposited layer616, including deposition method, time, and cycles. As such, all parameters discussed at block130apply to block140.

In one or more embodiments, the third precursor is or includes one or more aluminum precursors; however, the third precursor can be or include one or more aluminum precursors, one or more chromium precursors, one or more hafnium precursors, one or more yttrium precursors, or any combination thereof. In some examples, such asFIG.6A, the first deposited layer624is a hafnium doped aluminum oxide, the second deposited layer616is a chromium-containing layer that contains chromium oxide, and the third deposited layer618is an aluminum-containing layer that contains one or more of aluminum oxide.

At block150, the method100includes optionally repeating exposing the aerospace component502,602to the first precursor and the first reactant, the second precursor and the second reactant, and/or the third precursor and the third reactant one or more times until a desired thickness is reached or achieved, such as shown inFIGS.5A and6A. If the desired thickness of the protective coating200,300,400has been achieved, then move to block160. If the desired thickness of the protective coating500,600has not been achieved, then start another deposition cycle of exposing the aerospace component502to the first precursor and the first reactant to form a third deposited layer518, exposing the aerospace component502to the second precursor and the second reactant to form a fourth deposited layer520, and exposing the aerospace component502to the first precursor and the first reactant to form a fifth deposited layer522like shown inFIG.5A, or by exposing the aerospace component602to the second precursor and the second reactant to form a fourth deposited layer620and exposing the aerospace component602to the third precursor and the third reactant to form a fifth deposited layer622, like shown inFIG.6A. The deposition cycle is repeated until achieving the desired thickness of the protective coating500,600.

In one or more embodiments, the protective coating500,600can contain from 1, 2, 3, 4, 5, 6, 7, 8, or 9 pairs of the first and second deposited layers (e.g.,504A and516,518and520) or the second and third deposited layers (e.g.,616and618,620and622) to about 10, about 12, about 15, about 20, about 25, about 30, about 40, about 50, about 65, about 80, about 100, about 120, about 150, about 200, about 250, about 300, about 500, about 800, or about 1,000 pairs of the first and second deposited layers504A,516or the second and third deposited layers616,618. For example, the protective coating500,600can contain from 1 to about 1,000, 1 to about 800, 1 to about 500, 1 to about 300, 1 to about 250, 1 to about 200, 1 to about 150, 1 to about 120, 1 to about 100, 1 to about 80, 1 to about 65, 1 to about 50, 1 to about 30, 1 to about 20, 1 to about 15, 1 to about 10, 1 to about 8, 1 to about 6, 1 to 5, 1 to 4, 1 to 3, about 5 to about 150, about 5 to about 120, about 5 to about 100, about 5 to about 80, about 5 to about 65, about 5 to about 50, about 5 to about 30, about 5 to about 20, about 5 to about 15, about 5 to about 10, about 5 to about 8, about 5 to about 7, about 10 to about 150, about 10 to about 120, about 10 to about 100, about 10 to about 80, about 10 to about 65, about 10 to about 50, about 10 to about 30, about 10 to about 20, about 10 to about 15, or about 10 to about 12 pairs of the first and second deposited layers504A,516or the second and third deposited layers616,618. In one or more embodiments, the protective coating500,600can contain an odd number of layers such that there is an additional first deposited layer, second deposited layer, or third deposited layer, like shown inFIG.5A.

The protective coating200,300,400,500,600can have a total thickness of about 1 nm, about 2 nm, about 3 nm, about 5 nm, about 8 nm, about 10 nm, about 12 nm, about 15 nm, about 20 nm, about 30 nm, about 50 nm, about 60 nm, about 80 nm, about 100 nm, or about 120 nm to about 150 nm, about 180 nm, about 200 nm, about 250 nm, about 300 nm, about 350 nm, about 400 nm, about 500 nm, about 800 nm, about 1,000 nm, about 2,000 nm, about 3,000 nm, about 4,000 nm, about 5,000 nm, about 6,000 nm, about 7,000 nm, about 8,000 nm, about 9,000 nm, about 10,000 nm, or thicker. In some examples, the protective coating200,300,400,500,600can have a thickness of less than 10 μm (less than 10,000 nm). For example, the protective coating200,300,400,500,600can have a thickness of about 1 nm to less than 10,000 nm, about 1 nm to about 8,000 nm, about 1 nm to about 6,000 nm, about 1 nm to about 5,000 nm, about 1 nm to about 3,000 nm, about 1 nm to about 2,000 nm, about 1 nm to about 1,500 nm, about 1 nm to about 1,000 nm, about 1 nm to about 500 nm, about 1 nm to about 400 nm, about 1 nm to about 300 nm, about 1 nm to about 250 nm, about 1 nm to about 200 nm, about 1 nm to about 150 nm, about 1 nm to about 100 nm, about 1 nm to about 80 nm, about 1 nm to about 50 nm, about 20 nm to about 500 nm, about 20 nm to about 400 nm, about 20 nm to about 300 nm, about 20 nm to about 250 nm, about 20 nm to about 200 nm, about 20 nm to about 150 nm, about 20 nm to about 100 nm, about 20 nm to about 80 nm, about 20 nm to about 50 nm, about 30 nm to about 400 nm, about 30 nm to about 200 nm, about 50 nm to about 500 nm, about 50 nm to about 400 nm, about 50 nm to about 300 nm, about 50 nm to about 250 nm, about 50 nm to about 200 nm, about 50 nm to about 150 nm, about 50 nm to about 100 nm, about 80 nm to about 250 nm, about 80 nm to about 200 nm, about 80 nm to about 150 nm, about 80 nm to about 100 nm, about 50 nm to about 80 nm, about 100 nm to about 500 nm, about 100 nm to about 400 nm, about 100 nm to about 300 nm, about 100 nm to about 250 nm, about 100 nm to about 200 nm, or about 100 nm to about 150 nm.

At block160, an optional oxidation and annealing process is performed on the protective coating200,300,400,500,600, as shown inFIGS.2B,3B,4B,5B, and6B. For example, the optional annealing and oxidation process may be performed when one or more of the deposited layers are deposited in the amorphous phase. Additionally, if one or more layers are deposited by a CVD process, the CVD process may convert the one or more layers to a crystalline phase. As such, the protective coating200,300,400,500,600may not need to undergo the annealing and oxidation process. However, the one or more layers deposited through a CVD process may need to undergo the annealing and oxidation process to convert the one or more layers to the preferred crystalline assembly. The annealing and oxidation process may be performed at a temperature of about 500° C. to about 1,100° C.

The oxidizing process may partially oxidize the protective coating200,300,400,500,600. In some examples, the protective coating200,300,400,500,600can be converted into the coalesced layer208,308,408,508,608during the oxidation and annealing process. During the oxidation and annealing process, the high temperature coalesces the layers within the protective coating200,300,400,500,600into a single structure where the new crystalline assembly enhances the integrity and protective properties of the protective coating200or the coalesced layer208,308,408,508,608.

The protective coating200,300,400,500,600having a crystalline assembly enhances the strength, longevity, and durability of the protective coating200,300,400,500,600, and reduces both the oxidation rate of the surface of the aerospace component202,302,402,502,602and the rate of depletion of aluminum from the aerospace component202,302,402,502,602. As such, the protective coating200,300,400,500,600being in a crystalline phase increases the oxidation and corrosion resistance of the aerospace component202,302,402,502,602. The annealing process can be or include a thermal anneal, a plasma anneal, an ultraviolet anneal, a laser anneal, or any combination thereof. Additionally, each deposited layer of the protective coating200,300,400,500,600may be annealed and oxidized individually prior to depositing another layer, rather than annealing and oxidizing all deposited layers together at the same time. Performing the optional annealing and oxidizing process may further enhance and strengthen the protective properties of the protective coating200,300,400,500,600.

Furthermore, during the oxidation and annealing process, a layer or region206,306,406,506,606of the aerospace component202,302,402,502,602nearest the protective coating200,300,400,500,600is depleted of aluminum or an aluminum-rich phase, forming the intermediate region206,306,406,506,606disposed between the aerospace component202,302,402,502,602and the first deposited layer204,310A,404A,504A,624, and further forming an aluminum oxide layer or region204,314,404B,504B,624in the coalesced layer208,308,408,508,608. Aluminum from the intermediate region206,306,406,506,606diffuses into the coalesced layer208,308,408,508,608, depleting the intermediate region206,306,406,506,606of aluminum and simultaneously forming the aluminum oxide layer or region204,314,404B,504B,624. The aluminum oxide layer or region204,314,404B,504B,624is formed having a crystalline assembly.

The thickness of the intermediate region206,306,406,506,606may vary due to several factors, such as the amount of aluminum present in the aerospace component202,302,402,502,602, the amount of time the protective coating200,300,400,500,600is annealed, and the temperature of the annealing process. However, the protective coating200,300,400,500,600having the preferred crystalline assembly decreases the rate of depletion of aluminum from the intermediate region206,306,406,506,606, and further protects the aerospace component202,302,402,502,602from corrosion and oxidation.

The crystalline protective coatings200,300,400,500,600reduces the amount of nickel containing oxides formed at the surface of the aerospace component202,302,402,502,602. For example, utilizing the protective coatings200,300,400,500,600results in less than 10% of nickel containing oxides from forming on the surface of the aerospace component202,302,402,502,602, such as less than 5%.

During the oxidation and annealing process, the protective coating200,300,400,500,600disposed on the aerospace component202,302,402,502,602is heated to a temperature of greater than about 500° C. In some embodiments, the protective coating200,300,400,500,600disposed on the aerospace component202,302,402,502,602is heated to a temperature of greater than about 800° C. For example, the protective coating200,300,400,500,600disposed on the aerospace component202,302,402,502,602is heated to a temperature of about 500° C. to about 1,500° C., about 600° C. to about 1,400° C., about 700° C. to about 1,300° C., about 800° C. to about 1,200° C., about 900° C. to about 1,100° C., about 900° C. to about 1,000° C., or about 1050° C. during the oxidation and annealing process. The oxidation and annealing process may occur in an environment of air. If more than one annealing and oxidation process is performed (i.e., annealing and oxidizing deposited layers individually), each annealing and oxidizing process may occur at the same temperature, or each annealing and oxidizing process may occur at different temperatures.

The protective coating200,300,400,500,600can be under a vacuum at a low pressure (e.g., from about 0.1 Torr to less than 760 Torr), at ambient pressure (e.g., about 760 Torr), and/or at a high pressure (e.g., from greater than 760 Torr (1 atm) to about 3,678 Torr (about 5 atm)) during the oxidation and annealing process. The protective coating200,300,400,500,600can be exposed to an atmosphere containing one or more gases during the oxidation and annealing process. Exemplary gases used during the annealing process can be or include nitrogen (N2), argon, helium, hydrogen (H2), oxygen (O2), air, or any combinations thereof. The oxidation and annealing process can be performed for about 0.01 seconds to about 10 minutes. In some examples, the oxidation and annealing process can be a thermal anneal and lasts for about 1 minute to about 24 hours, such as about 10 minutes to about 10 hours. In other examples, the oxidation and annealing process can be a laser anneal or a spike anneal and lasts for about 1 millisecond, about 100 millisecond, or about 1 second to about 5 seconds, about 10 seconds, or about 15 seconds.

The protective coating200,300,400,500,600can have a thickness of about 1 nm, about 2 nm, about 3 nm, about 5 nm, about 8 nm, about 10 nm, about 12 nm, about 15 nm, about 20 nm, about 30 nm, about 50 nm, about 60 nm, about 80 nm, about 100 nm, or about 120 nm to about 150 nm, about 180 nm, about 200 nm, about 250 nm, about 300 nm, about 350 nm, about 400 nm, about 500 nm, about 700 nm, about 850 nm, about 1,000 nm, about 1,200 nm, about 1,500 nm, about 2,000 nm, about 3,000 nm, about 4,000 nm, about 5,000 nm, about 6,000 nm, about 7,000 nm, about 8,000 nm, about 9,000 nm, about 10,000 nm, or thicker. In some examples, the protective coating250or the coalesced film240can have a thickness of less than 10 μm (less than 10,000 nm). For example, protective coating200,300,400,500,600can have a thickness of about 1 nm to less than 10,000 nm, about 1 nm to about 8,000 nm, about 1 nm to about 6,000 nm, about 1 nm to about 5,000 nm, about 1 nm to about 3,000 nm, about 1 nm to about 2,000 nm, about 1 nm to about 1,500 nm, about 1 nm to about 1,000 nm, about 1 nm to about 500 nm, about 1 nm to about 400 nm, about 1 nm to about 300 nm, about 1 nm to about 250 nm, about 1 nm to about 200 nm, about 1 nm to about 150 nm, about 1 nm to about 100 nm, about 1 nm to about 80 nm, about 1 nm to about 50 nm, about 20 nm to about 500 nm, about 20 nm to about 400 nm, about 20 nm to about 300 nm, about 20 nm to about 250 nm, about 20 nm to about 200 nm, about 20 nm to about 150 nm, about 20 nm to about 100 nm, about 20 nm to about 80 nm, about 20 nm to about 50 nm, about 30 nm to about 400 nm, about 30 nm to about 200 nm, about 50 nm to about 500 nm, about 50 nm to about 400 nm, about 50 nm to about 300 nm, about 50 nm to about 250 nm, about 50 nm to about 200 nm, about 50 nm to about 150 nm, about 50 nm to about 100 nm, about 80 nm to about 250 nm, about 80 nm to about 200 nm, about 80 nm to about 150 nm, about 80 nm to about 100 nm, about 50 nm to about 80 nm, about 100 nm to about 500 nm, about 100 nm to about 400 nm, about 100 nm to about 300 nm, about 100 nm to about 250 nm, about 100 nm to about 200 nm, or about 100 nm to about 150 nm.

In one or more embodiments, the protective coating200,300,400,500,600can have a relatively high degree of uniformity. The protective coating200,300,400,500,600can have a uniformity of less than 50%, less than 40%, or less than 30% of the thickness of the respective protective coating200,250. The protective coating200,300,400,500,600can independently have a uniformity from about 0%, about 0.5%, about 1%, about 2%, about 3%, about 5%, about 8%, or about 10% to about 12%, about 15%, about 18%, about 20%, about 22%, about 25%, about 28%, about 30%, about 35%, about 40%, about 45%, or less than 50% of the thickness. For example, the protective coating200,300,400,500,600can independently have a uniformity from about 0% to about 50%, about 0% to about 40%, about 0% to about 30%, about 0% to less than 30%, about 0% to about 28%, about 0% to about 25%, about 0% to about 20%, about 0% to about 15%, about 0% to about 10%, about 0% to about 8%, about 0% to about 5%, about 0% to about 3%, about 0% to about 2%, about 0% to about 1%, about 1% to about 50%, about 1% to about 40%, about 1% to about 30%, about 1% to less than 30%, about 1% to about 28%, about 1% to about 25%, about 1% to about 20%, about 1% to about 15%, about 1% to about 10%, about 1% to about 8%, about 1% to about 5%, about 1% to about 3%, about 1% to about 2%, about 5% to about 50%, about 5% to about 40%, about 5% to about 30%, about 5% to less than 30%, about 5% to about 28%, about 5% to about 25%, about 5% to about 20%, about 5% to about 15%, about 5% to about 10%, about 5% to about 8%, about 10% to about 50%, about 10% to about 40%, about 10% to about 30%, about 10% to less than 30%, about 10% to about 28%, about 10% to about 25%, about 10% to about 20%, about 10% to about 15%, or about 10% to about 12% of the thickness.

In some embodiments, the protective coating200,300,400,500,600contain can be formed or otherwise produced with different ratios of metals throughout the material, such as a doping metal or grading metal contained within a base metal, where any of the metal can be in any chemically oxidized form (e.g., oxide, nitride, silicide, carbide, or combinations thereof). In one or more examples, the first deposited layer204,310A,404A,504A,624is deposited to first thickness and the second deposited layer410A,516,616is deposited to a second thickness, where the first thickness or less than or greater than the second thickness. For example, the first deposited layer204,310A,404A,504A,624can be deposited by two or more (3, 4, 5, 6, 7, 8, 9, 10, or more) ALD cycles during block120to produce the respectively same amount of sub-layers (e.g., one sub-layer for each ALD cycle), and then the second deposited layer410A,516,616can be deposited by one ALD cycle or a number of ALD cycles that is less than or greater than the number of ALD cycles used to deposit the first deposited layer204,310A,404A,504A, or624. In other examples, the first deposited layer204,310A,404A,504A,624can be deposited by CVD to a first thickness and the second deposited layer410A,516,616is deposited by ALD to a second thickness which is less than the first thickness.

In other embodiments, an ALD process can be used to deposit the first deposited layer204,310A,404A,504A,624and/or the second deposited layer410A,516,616where the deposited material is doped by including a dopant precursor during the ALD process. In some examples, the dopant precursor can be included in a separate ALD cycle relative to the ALD cycles used to deposit the base material. In other examples, the dopant precursor can be co-injected with any of the chemical precursors used during the ALD cycle. In further examples, the dopant precursor can be injected separate from the chemical precursors during the ALD cycle. For example, one ALD cycle can include exposing the aerospace component to: the first precursor, a pump-purge, the dopant precursor, a pump-purge, the first reactant, and a pump-purge to form the deposited layer. In some examples, one ALD cycle can include exposing the aerospace component to: the dopant precursor, a pump-purge, the first precursor, a pump-purge, the first reactant, and a pump-purge to form the deposited layer. In other examples, one ALD cycle can include exposing the aerospace component to: the first precursor, the dopant precursor, a pump-purge, the first reactant, and a pump-purge to form the deposited layer.

In one or more embodiments, the first deposited layer204,310A,404A,504A,624and/or the second deposited layer410A,516,616contains one or more base materials and one or more doping materials. The base material is or contains aluminum oxide, chromium oxide, or a combination of aluminum oxide and chromium oxide. The doping material is or contains hafnium, hafnium oxide, yttrium, yttrium oxide, cerium, cerium oxide, silicon, silicon oxide, nitrides thereof, or any combination thereof. Any of the precursors or reagents described herein can be used as a doping precursor or a dopant. Exemplary cerium precursor can be or include one or more cerium(IV) tetra(2,2,6,6-tetramethyl-3,5-heptanedionate) (Ce(TMHD)4), tris(cyclopentadiene) cerium ((C5H5)3Ce), tris(propylcyclopentadiene) cerium ([(C3H7)C5H4]3Ce), tris(tetramethylcyclopentadiene) cerium ([(CH3)4C5H]3Ce), or any combination thereof.

FIGS.7A and7Bare schematic views of an aerospace component700comprising nickel and aluminum having a protective coating730disposed thereon, according to one or more embodiments described and discussed herein.FIG.7Ais a perspective view of the aerospace component700andFIG.7Bis a cross-sectional view of the aerospace component700. The protective coating730can be or include one or more deposited layers, one or more coalesced films, or any combination thereof, as described and discussed herein. For example, the protective coating730can be or include one or more of the protective coating200ofFIG.2B, the protective coating300ofFIG.3B, the protective coating400ofFIG.4B, the protective coating500ofFIG.5B, and/or the protective coating600ofFIG.6B. Similarly, the aerospace component700can be or include the aerospace component202,302,402,502,602ofFIGS.2A-2B,FIGS.3A-3B,FIGS.4A-4B,FIGS.5A-5B, andFIGS.6A-6B, respectively. Aerospace components as described and discussed herein, including aerospace component700, can be or include one or more components or portions thereof of a turbine, an aircraft, a spacecraft, or other devices that can include one or more turbines (e.g., compressors, pumps, turbo fans, super chargers, and the like). Exemplary aerospace components700can be or include a turbine blade, a turbine vane, a support member, a frame, a rib, a fin, a pin fin, a combustor fuel nozzle, a combustor shield, an internal cooling channel, or any combination thereof.

The aerospace component700has one or more outer or exterior surfaces710and one or more inner or interior surfaces720. The interior surfaces720can define one or more cavities702extending or contained within the aerospace component700. The cavities702can be channels, passages, spaces, or the like disposed between the interior surfaces720. The cavity702can have one or more openings704,706, and708. Each of the cavities702within the aerospace component700typically have aspect ratios (e.g., length divided by width) of greater than 1. The methods described and discussed herein provide depositing and/or otherwise forming the protective coatings200,300,400,500,600on the interior surfaces720with high aspect ratios (greater than 1) and/or within the cavities702.

The aspect ratio of the cavity702can be from about 2, about 3, about 5, about 8, about 10, or about 12 to about 15, about 20, about 25, about 30, about 40, about 50, about 65, about 80, about 100, about 120, about 150, about 200, about 250, about 300, about 500, about 800, about 1,000, or greater. For example, the aspect ratio of the cavity702can be from about 2 to about 1,000, about 2 to about 500, about 2 to about 200, about 2 to about 150, about 2 to about 120, about 2 to about 100, about 2 to about 80, about 2 to about 50, about 2 to about 40, about 2 to about 30, about 2 to about 20, about 2 to about 10, about 2 to about 8, about 5 to about 1,000, about 5 to about 500, about 5 to about 200, about 5 to about 150, about 5 to about 120, about 5 to about 100, about 5 to about 80, about 5 to about 50, about 5 to about 40, about 5 to about 30, about 5 to about 20, about 5 to about 10, about 5 to about 8, about 10 to about 1,000, about 10 to about 500, about 10 to about 200, about 10 to about 150, about 10 to about 120, about 10 to about 100, about 10 to about 80, about 10 to about 50, about 10 to about 40, about 10 to about 30, about 10 to about 20, about 20 to about 1,000, about 20 to about 500, about 20 to about 200, about 20 to about 150, about 20 to about 120, about 20 to about 100, about 20 to about 80, about 20 to about 50, about 20 to about 40, or about 20 to about 30.

The aerospace component700and any surface thereof including one or more outer or exterior surfaces710and/or one or more inner or interior surfaces720can be made of, contain, or otherwise include one or more metals, such as nickel, aluminum, chromium, iron, titanium, hafnium, one or more nickel superalloys, one or more Inconel alloys, one or more Hastelloy alloys, one or more Monel alloys, alloys thereof, or any combination thereof. For example, the aerospace component700may comprise Inconel 617, Inconel 625, Inconel 718, Inconel X-750, Haynes 214 alloy, Monel 404, and/or Monel K-500. The protective coating730can be deposited, formed, or otherwise produced on any surface of the aerospace component700including one or more outer or exterior surfaces710and/or one or more inner or interior surfaces720.

The protective coating, as described and discussed herein, can be or include one or more of laminate film stacks, coalesced films, graded compositions, and/or monolithic films which are deposited or otherwise formed on any surface of an aerospace component. In some examples, the protective coating contains from about 1% to about 100% chromium oxide. The protective coatings are conformal and substantially coat rough surface features following surface topology, including in open pores, blind holes, and non-line-of sight regions of a surface. The protective coatings do not substantially increase surface roughness, and in some embodiments, the protective coatings may reduce surface roughness by conformally coating roughness until it coalesces. The protective coatings may contain particles from the deposition that are substantially larger than the roughness of the aerospace component, but are considered separate from the monolithic film. The protective coatings are substantially well adhered and pinhole free. The thickness of the protective coatings varies within 1-sigma of 40%. In one or more embodiments, the thickness varies less than 1-sigma of 20%, 10%, 5%, 1%, or 0.1%.

The protective coatings provide corrosion and oxidation protection when the aerospace components are exposed to air, oxygen, sulfur and/or sulfur compounds, acids, bases, salts (e.g., Na, K, Mg, Li, or Ca salts), or any combination thereof.

One or more embodiments described herein include methods for the preservation of an underneath chromium-containing alloy using the methods producing an alternating nanolaminate of first material (e.g., chromium oxide, aluminum oxide, and/or aluminum nitride) and another secondary material. The secondary material can be or include one or more of aluminum oxide, aluminum nitride, aluminum oxynitride, silicon oxide, silicon nitride, silicon carbide, yttrium oxide, yttrium nitride, yttrium silicon nitride, hafnium oxide, hafnium silicate, hafnium silicide, hafnium nitride, titanium oxide, titanium nitride, titanium silicide, titanium silicate, dopants thereof, alloys thereof, or any combination thereof. The resultant film can be used as a nanolaminate film stack or the film can be subjected to annealing where the high temperature coalesces the films into a single structure where the new crystalline assembly enhances the integrity and protective properties of this overlying film.

In a particular embodiment, the chromium precursor (at a temperature of about 0° C. to about 250° C.) is delivered to the aerospace component via vapor phase delivery for at pre-determined pulse length of 5 seconds. During this process, the deposition reactor is operated under a flow of nitrogen carrier gas (about 1,000 sccm total) with the chamber held at a pre-determined temperature of about 350° C. and pressure of about 3.5 Torr. After the pulse of the chromium precursor, the chamber is then subsequently pumped and purged of all requisite gases and byproducts for a determined amount of time. Subsequently, water is pulsed into the chamber for 0.1 seconds at chamber pressure of about 3.5 Torr. An additional chamber purge (or pump/purge) is then performed to rid the reactor of any excess reactants and reaction byproducts. This process is repeated as many times as necessary to get the target CrOx film to the desired film thickness.

For the secondary film (example: aluminum oxide), the precursor, trimethylaluminum (at a temperature of about 0° C. to about 30° C.) is delivered to the aerospace component via vapor phase delivery for at pre-determined pulse length of 0.1 seconds. During this process, the deposition reactor is operated under a flow of nitrogen carrier gas (100 sccm total) with the chamber held at a pre-determined temperature of about 150° C. to about 350° C. and pressure about 1 Torr to about 5 Torr. After the pulse of trimethylaluminum, the chamber is then subsequently pumped and purged of all requisite gases and byproducts for a determined amount of time. Subsequently, water vapor is pulsed into the chamber for about 0.1 seconds at chamber pressure of about 3.5 Torr. An additional chamber purge is then performed to rid the reactor of any excess reactants and reaction byproducts. This process is repeated as many times as necessary to get the target Al2O3film to the desired film thickness. The aerospace component is then subjected to an annealing furnace at a temperature of about 500° C. under inert nitrogen flow of about 500 sccm for about one hour.

Doped/alloyed ALD Layers Processes

One or more embodiments described herein include methods for the preservation of an underlying aerospace component by using a doped chromium-containing film or a doped aluminum containing film. This film is or includes a chromium-containing film produced by using a chromium precursor or an aluminum precursos, and one or more of oxygen sources or oxidizing agents (for chromium oxide or aluminum oxide deposition), nitrogen sources or nitriding agents (for chromium nitride or aluminum nitride deposition), one or more carbon sources or carbon precursors (for chromium carbide or aluminum carbide deposition), silicon sources or silicon precursors (for chromium silicide or aluminum silicide deposition), or any combination thereof. A doping precursor (or dopant) can be or include a source for aluminum, yttrium, hafnium, silicon, tantalum, zirconium, strontium, lanthanum, neodymium, holmium, barium, lutetium, dysprosium, samarium, terbium, erbium, thulium, titanium, niobium, manganese, scandium, europium, tin, cerium, or any combination thereof. The precursors used can be or include, but is not limited to, one or more chromium precursors or one or more aluminum precursors, as described and discussed above. The chromium precursor can be used during a deposition process to produce doped film containing the ternary material (e.g., YCrO or CrAlO). The resultant film can be used as a nanolaminate film stack or the film can be subjected to annealing where the high temperature coalesces the films into a single structure where the new crystalline assembly enhances the integrity and protective properties of this overlying film.

In a particular embodiment, the chromium precursor, bis(1,4-ditertbutyldiazadienyl chromium (II) (at a temperature of about 0° C. to about 250° C.) is delivered to the aerospace component via vapor phase delivery for at pre-determined pulse length of 5 seconds. During this process, the deposition reactor is operated under a flow of nitrogen carrier gas of about 1,000 sccm with the chamber held at a pre-determined temperature of about 350° C. and pressure of about 3.5 Torr. After the pulse of the chromium precursor, the chamber is then subsequently pumped and purged of all requisite gases and byproducts for a determined amount of time. Subsequently, a second reactant, water is pulsed into the chamber for 0.1 seconds at chamber pressure of about 3.5 Torr. A second chamber purge is then performed to rid the reactor of any excess reactants and reaction byproducts.

This chromium precursor/pump-purge/water/pump-purge sequence is repeated as many times as necessary to get the target CrOx film to the desired film thickness. This process results in the formation of a first CrOx laminate layer with desired thickness.

After the first CrOx laminate layer deposition, a third reactant, tetrakis(ethylmethylamino)hafnium (TEMAH) is pulsed into the chamber for 5 seconds at chamber pressure of about 1.6 Torr. A final chamber pump/purge is then performed to rid the reactor of any excess reactants and reaction byproducts. Subsequently, a second reactant, water is pulsed into the chamber for 3 seconds at chamber pressure of about 1.2 Torr. A second chamber pump/purge is then performed to rid the reactor of any excess reactants and reaction byproducts. This single sequence results in the formation of a second HfOx laminate layer with monolayer (HfOx) thickness.

This first CrOx/second HfOx laminate layer sequence is repeated as many times as necessary to get the target Hf-doped chromium oxide film (CrOx:Hf) to the desired film thickness. The resultant CrOx:Hf film can be used as a nanolaminate film stack or the film can be subjected to annealing where the high temperature activates Hf diffusion into a CrOx layers where the more uniform Hf distribution in CrOx:Hf film enhances the integrity and protective properties of this overlying film.

In a particular embodiment, the selected Al precursor, trimethylaluminum (TMAl) (at a temperature of about 0° C. to about 30° C.) is delivered to the aerospace component via vapor phase delivery for at pre-determined pulse length of about 0.1 seconds to about 1 second. During this process, the deposition reactor is operated under a flow of nitrogen carrier gas of about 100 sccm with the chamber held at a pre-determined temperature of about 150° C. to about 400° C. and pressure of about 1 Torr to about 5 Torr. After the pulse of trimethylaluminum, the chamber is then subsequently pumped and purged of all requisite gases and byproducts for a determined amount of time. Subsequently, water vapor is pulsed into the chamber for 3 seconds at chamber pressure of about 1 Torr to about 5 Torr. An additional chamber purge is then performed to rid the reactor of any excess reactants and reaction byproducts. The aluminum precursor/pump-purge/water/pump-purge sequence is repeated as many times as necessary to get the target AlOx (e.g., Al2O3) film to the desired film thickness. This process results in the formation of a first AlOx laminate layer with desired thickness.

After first AlOx laminate layer deposition, a third reactant, tetrakis(ethylmethylamino)hafnium (TEMAH) is pulsed into the chamber for about 5 seconds at chamber pressure of about 1.6 Torr. A final chamber pump/purge is then performed to rid the reactor of any excess reactants and reaction byproducts. Subsequently, a second reactant, water is pulsed into the chamber for about 3 seconds at chamber pressure of about 1.2 Torr. A second chamber pump/purge is then performed to rid the reactor of any excess reactants and reaction byproducts. This single sequence results in the formation of a second HfOx laminate layer with monolayer (HfOx) thickness.

This first AlOx/second HfOx laminate layer sequence is repeated as many times as necessary to get the target Hf-doped aluminum oxide film (AlOx:Hf) to the desired film thickness. In some examples, the resultant AlOx:Hf film is used as a nanolaminate film stack. In other examples, the resultant AlOx:Hf film is subjected to annealing where the high temperature activates Hf diffusion into a AlOx layers where the more uniform Hf distribution in AlOx:Hf film enhances the integrity and protective properties of this overlying film.

SEM shows cross-sections of ALD as-grown Hf doped Al2O3layers on Si aerospace component. SEM shows cross-section of Hf doped Al2O3layer with about 0.1 at % Hf concentration. The total Al2O3:Hf film thickness is about 140 nm. The film contains six Al2O3/HfO2laminate layers. The single Al2O3/HfO2laminate layer thickness is about 23 nm. SEM shows cross-section of Hf doped Al2O3layer with about 0.5 at % Hf concentration. The total Al2O3:Hf film thickness is about 108 nm. The film contains twenty one Al2O3/HfO2laminate layers. The single Al2O3/HfO2laminate layer thickness is about 5.1 nm.

The visual differentiation of HfO2and Al2O3layers on SEM cross section is clear seen for about 0.1 at % Hf doped sample. However SEM resolution (10 nm) limits the visual differentiation of HfO2and Al2O3layers for about 0.5 at % Hf doped sample. SIMS is used to determine concentration depth profiles of ALD as-grown Hf doped Al2O3layers on the aerospace component. A SIMS concentration depth profile of Hf doped Al2O3layer is about 0.1 at % Hf concentration. The film contains six Al2O3/HfO2laminate layers. A SIMS concentration depth profile of Hf doped Al2O3layer is about 0.5 at % Hf concentration. The film contains of twenty one Al2O3/HfO2laminate layers.

Rutherford backscattering spectrometry (RBS) provides compositional analysis data for ALD as-grown Hf doped Al2O3layers. The RBS analysis proved what bulk Al2O3:Hf layer with six Al2O3/HfO2laminate layers has about 0.1 at % Hf concentration, and bulk Al2O3:Hf layer with twenty one Al2O3/HfO2laminate layers has about 0.5 at % Hf concentration.

In one or more embodiments, the protective coatings which include chromium containing materials are desirable for a number of applications where a stable chromium oxide forms in air to protect the surface from oxidation, acid attack, and sulfur corrosion. In the instance of Fe, Co, and/or Ni-based alloys, chromium oxides (as well as aluminum oxides) are formed selectively to create a passivated surface. However, prior to forming this selective oxide layer, other metallic elements will oxidize until the chromium oxide forms a continuous layer.

After the formation of a dense chromium oxide layer, exposure to high temperatures (e.g., greater than 500° C.) in air causes thickening of the chromium oxide scale, where chromium diffuses out of the bulk metal and into the scale, and oxygen diffuses from the air into the scale. Over time, the scale growth rate slows as the scale thickens because (1) oxygen diffusion is slower and (2) chromium becomes depleted in the bulk alloy. For alloys, if the chromium concentration falls below a threshold, other oxides may begin to form which cause the spallation or failure of the previously protective scale.

To extend the life of a chromium-containing alloy, one or more of the following methods can be used. In one or more embodiments, the method can include depositing an oxide layer matching the composition and crystal structure of the native oxide to produce the protective coating. In other embodiments, the method can include depositing an oxide layer with a different crystal structure to the native oxide to produce the protective coating. In some embodiments, the method can include depositing an oxide layer with additional dopants that would not be present in the native oxide to produce the protective coating. In other embodiments, the method can include depositing another oxide (e.g., silicon oxide or aluminum oxide) as a capping layer or in a multi-layer stack to produce the protective coating.

In one or more embodiments of the method, a non-native oxide may be initially deposited onto the surface of the metal surface of aerospace component or other substrate that effectively thickens the oxide, thereby slowing oxygen diffusion toward the metal surface and resulting in slower absolute thicknesses growth of the oxide film. In some examples, a benefit of this approach can be contemplated in the context of a parabolic oxide scale growth curve. At thicker scales (e.g., greater than 0.5 micron to about 1.5 micron), the rate of scale thickness decreases versus initial growth. By depositing an oxide film having a thickness of about 100 nm, about 200 nm, or about 300 nm to about 1 micron, about 2 micron, or about 3 micron prior to the growth of a thick scale. The effective growth rate of the first thickness of about 0.5 micron to about 1 micron of native scale can be much slower over a given period of time. In turn, the rate of depletion of chromium from the substrate can be slower, and the time a surface can be exposed to the environment can be longer.

Oxygen diffusion can further be slowed by depositing a predetermined crystalline structure of chromium oxide, e.g., amorphous. Oxygen can diffuse along grain boundaries faster than in bulk crystals for chromium oxide, so minimizing grain boundaries can be beneficial for slowing oxygen diffusion. In turn, scale growth can be slower, and the time a surface can be exposed to the environment can be longer.

In other embodiments, the method can include incorporating one or more dopants into the deposited oxide while producing the protective coating. The dopant can be or include a source for aluminum, yttrium, hafnium, silicon, tantalum, zirconium, strontium, lanthanum, neodymium, holmium, barium, lutetium, dysprosium, samarium, terbium, erbium, thulium, titanium, niobium, manganese, scandium, europium, tin, cerium, or any combination thereof. The dopant can segregate to grain boundaries and modify grain boundary diffusion rates to slow the rate of oxide scale growth.

In one or more embodiments, an aerospace component includes a coating disposed on a surface of a substrate. The surface or substrate includes or contains nickel, nickel superalloy, aluminum, chromium, iron, titanium, hafnium, alloys thereof, or any combination thereof. The coating has a thickness of less than 10 μm and contains an aluminum oxide layer. In some examples, the surface of the aerospace component is an interior surface within a cavity of the aerospace component. The cavity can have an aspect ratio of about 5 to about 1,000 and the coating can have a uniformity of less than 30% of the thickness across the interior surface.

The crystalline protective coatings described above reduce the amount of nickel containing oxides formed at the surface of the aerospace component and further decreases the rate of aluminum depletion from the aerospace component. For example, utilizing the protective coatings results in less than 10% of nickel containing oxides from forming on the surface of the aerospace component such as less than 5%. Moreover, the protective coating having a crystalline assembly enhances the integrity and protective properties of the protective coating, as well as enhancing the strength, longevity, and durability of the protective coating. Utilizing the protective coating further reduces the oxidation rate of the surface of the aerospace component, increasing the oxidation and corrosion resistance of the aerospace component. By depositing the protective coating using ALD or CVD, the protective coating is substantially conformal.

While the foregoing is directed to examples of the present disclosure, other and further examples of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.