Multistep infiltration process

Abstract

A process for fabricating a ceramic matrix composite ("CMC"), comprising the steps of fabricating at least one ceramic fiber preform using at least one fiber or at least one fiber tow; depositing at least one structural support material on the at least one ceramic fiber preform to form at least one partially densified ceramic matrix composite; infiltrating and filling at least one pore of the at least one partially densified ceramic matrix composite with at least one particle contained in a solvent to form at least one particle infiltrated, partially densified ceramic matrix composite; removing the solvent from the at least one particle infiltrated, partially densified ceramic matrix composite; repeating the infiltration and filling step and removal step until achieving a particle loading amount for the at least one partially densified ceramic matrix composite; and, melt infiltrating the at least one particle infiltrated, partially densified ceramic matrix composite to form an at least partially melt-infiltrated ceramic matrix composite.

Description

RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOMULTISTEP INFILTRATION PROCESS FIELD OF THE INVENTION

[0001] The subject matter disclosed herein relates to a multistep infiltration process and, in particular, to a multistep infiltration process for partially densified ceramic matrix composites.BACKGROUND OF THE INVENTION

[0002] Due to their high heat resistance, mechanical strength, and stability, ceramic matrix materials ("CMCs") are often used in applications exhibiting high heat environments, e.g., greater than or equal to l,200°C, for high-temperature components of gas turbine engines, such as blades, combustion chamber liners, and blade outer air seals ("BOAS"). To increase efficiency and performance, engine temperatures may be pushed beyond l,200°C, thus requiring a need for CMCs exhibiting high temperature stability, e.g., greater than l,400°C.

[0003] When producing CMC materials, fibers and / or fiber tows may be embedded in a ceramic matrix to form a ceramic fiber preform. Next, the ceramic fiber preform may be impregnated with particles through a slurry infiltration process. Typically, the particles used in the slurry infiltration process have desirable properties. Loading the CMC preform with as many particles as possible may be advantageous for the resultant end product. However, achieving a high loading through the slurry infiltration process may be challenging. For instance, if the slurry contains too many particles, the particles may begin to cluster. And, particle clustering may increase slurry viscosity thus reducing the slurry's ability to penetrate the pores of the ceramic fiber preform. In turn, the particle loading may be reduced and the ceramic fiber preform may not exhibit particle loading uniformity throughout the preform.

[0004] For these reasons, there exists a need for achieving a desirable particle loading amount.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOSUMMARY OFTHE INVENTION

[0005] The present disclosure is directed, in a first aspect, to a method for fabricating a ceramic matrix composite, comprising the steps of: fabricating at least one ceramic fiber preform using at least one fiber or at least one fiber tow; optionally depositing an interface coating material on at least one fiber or at least one fiber tow to form at least one interface coated fiber or at least one interface coated fiber tow; depositing at least one structural support material on the at least one interface coated fiber or at least one interface coated fiber tow of the at least one ceramic fiber preform to form at least one partially densified ceramic matrix composite; optionally depositing a fiber protection material on the at least one partially densified ceramic matrix composite; infiltrating and filling at least one pore of the at least one partially densified ceramic matrix composite with at least one particle contained in a solvent to form at least one particle infiltrated, partially densified ceramic matrix composite; removing the solvent from the at least one particle infiltrated, partially densified ceramic matrix composite; repeating the infiltration and filling step and removal step until achieving a particle loading amount for the at least one partially densified ceramic matrix composite; melt infiltrating the at least one particle infiltrated, partially densified ceramic matrix composite to form an at least partially melt-infiltrated ceramic matrix composite; and optionally heat-treating the at least partially melt-infiltrated ceramic matrix composite to form a melt-infiltrated ceramic matrix composite.

[0006] In another embodiment, the present disclosure is directed to a ceramic matrix composite fabricated according to a process comprising the steps of: fabricating at least one ceramic fiber preform using at least one fiber or at least one fiber tow; optionally depositing an interface coating material on at least one fiber or at least one fiber tow to form at least one interface coated fiber or at least one interface coated fiber tow; depositing at least one structural support material on the at least one interface coated fiber or at least one interface coated fiber tow of the at least one ceramic fiber preform to form at least one partially densified ceramic matrix composite; optionallydepositinga fiber protection material on the at leastone partially densified ceramic matrix composite; infiltrating and filling at least one pore of the at least one partiallyRTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOdensified ceramic matrix composite with at least one particle contained in a solvent to form at least one particle infiltrated, partially densified ceramic matrix composite; removing the solvent from the at least one particle infiltrated, partially densified ceramic matrix composite; repeating the infiltration and filling step and removal step until achieving a particle loading amount for the at least one partially densified ceramic matrix composite; melt infiltrating the at least one particle infiltrated, partially densified ceramic matrix composite to form an at least partially melt-infiltrated ceramic matrix composite; and optionally heat-treating the at least partially melt-infiltrated ceramic matrix composite to form a melt-infiltrated ceramic matrix composite.

[0007] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the at least one fiber or the least one fiber tow comprises one or more of the following: silicon carbide, carbon, aluminum oxide, and silicon nitride.

[0008] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the at least one structural support material comprises one or more of the following: carbides, carbons, nitrides, and borides.

[0009] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the carbides comprise one or more of the following: silicon carbide and boron carbide.

[0010] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the carbons comprise at least pyrolytic carbon.

[0011] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the nitrides comprise at least silicon nitride or silicon nitro carbide.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO

[0012] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the at least one particle comprises one or more of the following: carbides, carbons, nitrides, borides, silicides, metals, and metalloids.

[0013] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the carbides comprise one or more of the following: boron carbides, zirconium carbides, hafnium carbides, tantalum carbides, niobium carbides, titanium carbides, molybdenum carbides, boron carbides, tungsten carbides, vanadium carbides, chromium carbides, ytterbium carbides, and yttrium carbides.

[0014] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the carbons comprise one or more of the following: pyrolytic carbon, graphite flake, graphite particle, graphite fiber, carbon nanotubes, carbon nanofibers, carbon nanoparticles, carbon nanowires, carbon nanoribbons, and diamond particles.

[0015] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the nitrides comprise one or more of the following: silicon nitrides, titanium nitrides, boron nitrides, zirconium nitrides, hafnium nitrides, niobium nitrides, tantalum nitrides, vanadium nitrides, ytterbium nitrides, and yttrium nitrides.

[0016] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the borides comprise one or more of the following: silicon borides, titanium borides, borides, zirconium borides, hafnium borides, niobium borides, tantalum borides, vanadium borides, ytterbium borides, and yttrium borides.

[0017] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the silicides comprise one or more of the following: Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, and Y-Si.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO

[0018] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the metals comprise one or more of the following: Zirconium, hafnium, tantalum, niobium, titanium, molybdenum, tungsten, vanadium, chromium, ytterbium, and yttrium.

[0019] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the metalloids comprise one or more of the following: boron and silicon.

[0020] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the melt infiltration step comprises melt-infiltrating one or more of the following: silicon and silicon alloys.

[0021] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the silicides comprise one or more of the following: Si, Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, and Y-Si.

[0022] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the optional heat-treating step comprises reacting at one or more of the following: transition metal, metal, metal alloy, metalloid, metalloid alloy; with one or more of the following: fiber protection material, at least one particle; within the at least partially infiltrated ceramic matrix.

[0023] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the at least one particle comprises at least one coarse particle and at least one fine particle.

[0024] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the at least one coarse particle comprises an average particle size of approximately 1 pm to approximately 100 pm.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO

[0025] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the at least one fine particle comprises an average particle size of approximately 50 nm to approximately 5 pm.

[0026] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the method further comprises repeating the infiltration and filling step and removal step further comprises the following steps: infiltrating and filling the at least one pore with the solvent and at least one first particle having a first average particle size; removing the solvent; infiltrating and filling the at least one pore with the solvent and at least one second particle having a second average particle size; and removing the solvent.

[0027] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the first average particle size is greater than the second average particle size.

[0028] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the first average particle size is less than the second average particle size.

[0029] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the at least one fiber or the least one fiber tow comprises one or more of the following: silicon carbide, carbon, aluminum oxide, and silicon nitride.

[0030] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the at least one structural support material comprises one or more of the following: carbides, carbons, nitrides and borides.

[0031] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the carbides comprise one or more of the following: silicon carbide and boron carbide.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO

[0032] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the carbons comprise at least pyrolytic carbon.

[0033] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the nitrides comprise at least silicon nitride or silicon nitro carbide.

[0034] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the at least one particle comprises one or more of the following: carbides, carbons, nitrides, borides, silicides, metals, and metalloids.

[0035] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the carbides comprise one or more of the following: boron carbides, zirconium carbides, hafnium carbides, tantalum carbides, niobium carbides, titanium carbides, molybdenum carbides, boron carbides, tungsten carbides, vanadium carbides, chromium carbides, ytterbium carbides, and yttrium carbides.

[0036] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the carbons comprise one or more of the following: pyrolytic carbon, graphite flake, graphite particle, graphite fiber, carbon nanotubes, carbon nanofibers, carbon nanoparticles, carbon nanowires, carbon nanoribbons, and diamond particles.

[0037] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the nitrides comprise one or more of the following: silicon nitrides, titanium nitrides, boron nitrides, zirconium nitrides, hafnium nitrides, niobium nitrides, tantalum nitrides, vanadium nitrides, ytterbium nitrides, and yttrium nitrides.

[0038] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the borides comprise one or more of the following: siliconRTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOborides, titanium borides, borides, zirconium borides, hafnium borides, niobium borides, tantalum borides, vanadium borides, ytterbium borides, and yttrium borides.

[0039] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the silicides comprise one or more of the following: Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, and Y-Si.

[0040] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the metals comprise one or more of the following: Zirconium, hafnium, tantalum, niobium, titanium, molybdenum, tungsten, vanadium, chromium, ytterbium, and yttrium.

[0041] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the metalloids comprise one or more of the following: boron and silicon.

[0042] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the melt infiltration step comprises melt-infiltrating one or more of the following: silicon and silicon alloys.

[0043] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the silicides comprise one or more of the following: Si, Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, and Y-Si.

[0044] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the optional heat-treating step comprises reacting one or more of the following: transition metal, metal, metal alloy, metalloid, metalloid alloy; with one or more of the following: fiber protection material, at least one particle; within the at least partially infiltrated ceramic matrix.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO

[0045] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, repeating the infiltration and filling step and removal step further comprises the following steps: infiltrating and filling the at least one pore with the solvent and at least one first particle having a first average particle size; removing the solvent; infiltrating and filling the at least one pore with the solvent and at least one second particle having a second average particle size; and removing the solvent.

[0046] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the first average particle size is greater than the second average particle size.

[0047] In further embodiments of the present disclosure, including further embodiments of the above exemplary embodiments, the first average particle size is less than the second average particle size.BRIEF DESCRIPTION OF FIGURES

[0048] The features of the disclosure believed to be novel and the elements characteristic of the invention are set forth with particularity in the appended claims. The figures are for illustration purposes only and are not drawn to scale. The disclosure itself, however, both as to organization and method of operation, can best be understood by reference to the description of the preferred embodiment(s) which follows, taken in conjunction with the accompanying drawings in which:

[0049] FIG. 1 is a flow chart illustrating the steps of an exemplary process for fabricating CMCs.

[0050] FIG. 2 is an illustration of a partially densified CMC prior to infiltration with at least one particle contained in a solvent, not to scale.

[0051] FIG. 3 is an illustration of the partially densified CMC of FIG. 2 after being infiltrated with at least one particle and exhibiting a particle loading, not to scale.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO

[0052] FIG. 4 is an illustration of the partially densified CIVIC of FIG. 3 after being infiltrated to maximize the particle loading, not to scale.DETAILED DESCRIPTION OF THE INVENTION

[0053] The embodiments of the present disclosure can comprise, consist of, and consist essentially of the features and / or steps described herein, as well as any of the additional or optional ingredients, components, steps, or limitations described herein or would otherwise be appreciated by one of skill in the art. It is to be understood that all concentrations disclosed herein are by weight percent (wt. %.) based on a total weight of the composition unless otherwise indicated.

[0054] As used herein, an "interface coated ceramic fiber preform" refers to an IFC ceramic fiber preform. As also used herein, a "partially densified CMC" refers to a coated substrate or preform that includes a structural support material layer that facilitates rigidization of the preform to become self-supporting. As also used further herein, a "ceramic matrix composite" or "CMC" refers to a matrix infiltrated into the coated substrate or coated preform or alternatively, a matrix infiltrated into the rigidized partially densified CMC.

[0055] The present disclosure is directed to a method for fabricating CMCs and, specifically, CMCs whose partially densified CMC exhibit maximum particle loading prior to undergoing meltinfiltration. To increase and achieve the desired maximum particle loading, the partially densified CMC may be infiltrated multiple times until the desired maximum particle loading is achieved. In general, the first slurry infiltration step may utilize a slurry containing a solvent and coarse particles and, with each successive slurry infiltration step performed, the particle size may decrease until the last slurry infiltration step may utilize a slurry containing a solvent and fine particles. Between each aforementioned slurry infiltration step, the slurry infiltrated partially densified CMC may be dried to remove the solvent, and create space for additional particles to occupy after each successive slurry infiltration step is performed.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO

[0056] Referring now to FIG. 1, a flowchart illustrating an exemplary method for fabricating a CMC is shown. At an exemplary step 100 of FIG. 1, at least one fiber or fiber tow may be utilized to fabricate a ceramic fiber preform. In at least one embodiment, a two-dimensional woven preform or a three-dimensional woven preform may include, respectively, a two-dimensional woven preform structure or a three-dimensional woven preform structure, fabricated by, for example, a two-dimensional weaving loom or a three-dimensional weaving loom. For example, representative three-dimensional woven structures for use in three-dimensional woven ceramic matrix composites may include, but are not limited to, angle interlock layer-to-layer, angle interlock through-the-thickness, and three-dimensional orthogonal; individually, and combinations thereof. The resultant two-dimensional woven ceramic fiber preform and three-dimensional woven ceramic fiber preform may ultimately be suitable for use as a CMC.

[0057] Next, at an exemplary step 200 of FIG. 1, an optional interface coating material may be deposited on at least one fiber or at least one fiber tow to form at least one interface coated fiber ("IFC") or at least one IFC fiber tow. In at least one embodiment, ceramic fibers, tows or plies suitable for use in CMCs may be utilized. For example, suitable ceramic fibers may include, but are not limited to, silicon carbide (SiC) fibers. For instance, suitable SiC fibers for use herein may include, but are not limited to, Hi-Nicalon™ and Hi-Nicalon™ Type S fibers; Tyranno ZMI and Tyranno SA fibers of Tyranno Fibers®; Sylramic fibers; combinations thereof, and the like. In another example, carbon fibers may also be suitable for use in CMC. In yet another example, suitable ceramic fibers for use herein may include, but are not limited to, aluminum oxide, silicon nitride, combinations thereof, and the like.

[0058] In at least one embodiment, the exemplary IFC material(s) may be disposed on the exterior surface of the fibers and / or fiber tows using any technique capable of depositing, adhering and coating the material on the exterior surface, as well as controlling the debonding and chemical compatibility of oxidation products with the fibers and / or fiber tows. For example, suitable IFC materials may include, but are not limited to, boron nitride (BN), carbon (C), Si-doped BN (SiBN), silicon nitride (SisN^, silicon carbide (SiC), boron carbide (B4C), combinations thereof,RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOand the like. Deposition may take place using any technique capable of depositing an IFC material on a fiber or a fiber tow. Suitable deposition techniques may include, but are not limited to, chemical vapor infiltration (CVI), chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), molecular-beam epitaxy; individually and combinations thereof, and the like. In at least one embodiment, the exemplary interface coating material(s) layer(s) may exhibit and possess an exemplary thickness of between one nanometer to low hundreds of nanometers. In at least other embodiments, the exemplary interface coating material(s) layer(s) may exhibit and possess an exemplary thickness(es) of, for example, approximately 1 nm to approximately 500 nm; approximately 30 nm to approximately 400 nm; approximately 50 nm to approximately 200 nm; approximately 70 nm to approximately 150 nm; approximately 80 nm to approximately 120 nm; including any range that can be constructed using the specific thickness values disclosed herein.

[0059] Next, at an exemplary step 300 of FIG. 1, a structural support material may be deposited on the IFC fiber or IFC fiber tow of the ceramic fiber preform to form a partially densified CMC. The structural support materials may be any material suitable for fabricating a resultant self-supporting partially densified CMC. Suitable structural support materials may include, but are not limited to, carbides, e.g., silicon carbide, boron carbide; carbons, e.g., pyrolytic carbon; nitrides, e.g., silicon nitride, silicon nitro carbide; individually, and combinations thereof, and the like. Deposition of the structural support material may take place using any technique capable of depositing the material on the IFC fibers and / or the IFC fiber tows of the partially densified CMC. Suitable deposition techniques may include, but are not limited to, chemical vapor infiltration (CVI), chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), molecular-beam epitaxy; individually, and combinations thereof, and the like. In at least one embodiment, the deposited structural support coating may exhibit and possess an exemplary thickness of 1 pm to 500 pm.

[0060] Next, at an exemplary step 400 of FIG. 1, an optional fiber protection material may be deposited on the partially densified CMC. The fiber protection material may be any materialRTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOcapable of protecting the partially densified CMC from a molten infiltrant during a meltinfiltration step performed later in the exemplary process disclosed herein. Suitable fiber protection materials may include, but are not limited to, pyrolytic carbon, boron carbide, silicon nitride, silicon nitro carbide, borides, combinations thereof, and the like. Deposition of the fiber protection materials may take place using any technique capable of depositing the material on and within the partially densified CMC. Suitable fiber protection material deposition techniques may include, but are not limited to, chemical vapor infiltration (CVI), chemical vapor deposition (CVD), physical vapor deposition (PVD), atomic layer deposition (ALD), molecular-beam epitaxy; individually, and combinations thereof, and the like. In at least some embodiments, the deposited fiber protection material coating may exhibit and possess an exemplary thickness of 100 nm to 30 pm.

[0061] Next, at an exemplary step 500 of FIG. 1, an exemplary slurry containing a solvent and at least one particle may be provided for infiltrating and filling at least one pore of the partially densified CMC. In at least one embodiment, the slurry may include various additives including, but not limited to, binders, wetting agents, carbon sources, various particles (e.g., carbons, metals, carbides, nitrides, borides, oxides, combinations thereof, and the like), pH adjusters, dispersants and ice crystal modifiers, combinations thereof, and the like. The aforementioned additives may be present in various concentrations, e.g., by weight percent, volume percent, and the like; based on the slurry, and in various ratios with respect to each other, to optimize the efficiency of each slurry infiltration performed. For example, the binders may be selected and present in an amount suitable for impacting a viscosity of the slurry and ensuring uniform distribution of the particles. In at least one embodiment, one or more wetting agents may be present in an amount of less than approximately 10 percent by volume of the slurry. In at least one other embodiment, one or more carbon sources may be present in an amount of approximately 60 percent or less by volume of the slurry. In at least another embodiment, one or more various particles may be present in an amount of approximately 5 percent to approximately 80 percent by volume of the slurry. In at least yet another embodiment, one orRTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOmore pH adjusters may be present in an amount of lessthan approximately 10 percent by volume of the slurry. In at least yet another embodiment, one or more dispersants may be present in an amount of less than approximately 10 percent by volume of the slurry. And, in at least yet another embodiment, one or more ice crystal modifiers may be present in an amount of less than approximately 30 percent by volume.

[0062] In at least one embodiment, the carbon sources may include, but are not limited to, pyrolytic carbon, graphite flake, graphite particle, graphite fiber, carbon nanotubes, carbon nanofibers, carbon nanoparticles, carbon nanowires, carbon nanoribbons, diamond particles, combinations thereof, and the like. In at least one embodiment, the carbides may include, but are not limited to, boron carbides, zirconium carbides, hafnium carbides, tantalum carbides, niobium carbides, titanium carbides, molybdenum carbides, boron carbides, tungsten carbides, vanadium carbides, chromium carbides, ytterbium carbides, yttrium carbides, combinations thereof, and the like. In at least one embodiment, the nitrides may include, but are not limited to, silicon nitrides, titanium nitrides, boron nitrides, zirconium nitrides, hafnium nitrides, niobium nitrides, tantalum nitrides, vanadium nitrides, ytterbium nitrides, yttrium nitrides, combinations thereof, and the like. In at least one embodiment, the borides may include, but are not limited to, silicon borides, titanium borides, borides, zirconium borides, hafnium borides, niobium borides, tantalum borides, vanadium borides, ytterbium borides, yttrium borides, combinations thereof, and the like. In at least one embodiment, the silicides may include, but are not limited to, Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, Y-Si, combinations thereof, and the like. In at least one embodiment, the metals may include, but are not limited to, zirconium, hafnium, tantalum, niobium, titanium, molybdenum, tungsten, vanadium, chromium, ytterbium, yttrium, combinations thereof, and the like. In at least one embodiment, the metalloids may include, but are not limited to, boron, silicon, combinations thereof, and the like.

[0063] As mentioned above, the particles may be incorporated in various amounts, e.g., ratios of one type of particle to another type of particle, and various particle size distributions. ForRTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOexample, in at least one embodiment, the particles may be a mixture of at least one metal carbide, e.g., silicon carbide, and at least one carbon source, e.g., diamond. With respect to a possible average particle size distribution, a coarse particle may exhibit and possess an average size of approximately 1 pm to approximately 100 pm. In contrast, a fine particle may exhibit and possess an average size of approximately less than 1 pm to approximately 10 pm, and preferably from approximately 50 nm to approximately 100 nm up to approximately 5 pm, depending on the average particle size of the coarse particles. For example, if a coarse particle exhibiting an average particle size of, e.g., 1 pm, is first infiltrated, the next infiltration step may utilize a fine particle exhibiting a much smaller average size, e.g., 50 nm. For instance, in at least one other embodiment, a slurry containing, e.g., a coarse particle having an average particle size of approximately 15 pm may first be infiltrated into the partially densified CMC, followed by another slurry containing, e.g., a fine particle having an average particle size of approximately 0.5 pm. With each successive infiltration and filling step and solvent removal step are performed, an even smallerfine particle, e.g., diamond, may be infiltrated next. These steps may be repeated until a desired overall loading of particles may be achieved.

[0064] Any slurry infiltration technique may be utilized when carrying out the exemplary process disclosed herein. Suitable slurry infiltration techniques may include, but are not limited to, submersion, spraying, dip coating, transfer molding, painting, combinations thereof, and the like. For example, the aforementioned slurry may be poured or injected into the partially densified CMC. In at least one other embodiment, the partially densified CMC may be dipped to allow pickup of the slurry contents and solvent. In at least one other embodiment, a combination of methods may be utilized to deliver the slurry to the partially densified CMC in alternative steps or to different locations of the partially densified CMC. The solvent may be water or aqueousbased, or an alcohol- or solvent-based non-aqueous fluid that is chemically compatible with the partially densified CMC and the slurry contents. The solvent may be removed through a single or iterative vacuum and / or drying processes priorto a melt-infiltration step discussed below. TheRTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOslurry infiltration process may be conducted at standard pressure, e.g., 1 atm, or may be vacuum-or pressure-assisted.

[0065] In practice, when the pores of the partially densified CMC are initially infiltrated with the slurry for the first time, at least one microchannels, e.g., a series of microchannels, may be formed throughout the pores and / or porous structure of the aforementioned partially densified CMC. At an exemplary step 600 of FIG. 1, the solvent remaining with the microchannels and pores and / or porous structure of the now slurry infiltrated aforementioned partially densified CMC may be removed. The solvent removal technique may be any technique capable of removing the solvent while leaving intact the microchannels formed by the slurry infiltrated coarse and fine particles. Suitable solvent removal techniques may include, but are not limited to, sublimation, e.g., freeze drying; evaporation, e.g., thermal drying; super critical drying; individually, and combinations thereof, and the like. At an exemplary step 700 of FIG. 1, with each successive slurry infiltration step and solvent removal step performed, the average particle size of both the coarse particles and fine particles may be reduced. Concurrently, with each successive slurry infiltration step performed, the width / size / diameter of each microchannel of the aforementioned partially densified CMC may be gradually reduced. By the time the last or final slurry infiltration step is performed, the width / size / diameter of each microchannel may be narrowed and reduced by the successive addition of smaller and smaller coarse and fine particles each time, until each microchannel is filled and a maximum particle loading is achieved to form a particle infiltrated, partially densified CMC. As illustrated in FIGS. 2-4, a partially densified CMC 1000, prior to infiltration, may include at least one fiber 1100 that may be contained within or present in the form of a bundle of fibers more commonly known as a fiber tow 1200 or at least one fiber tow 1200. Between the fiber tows 1200, at least one pore 1300 of a porous structure within and at the surface of the partially densified CMC 1000 may be found (see FIG. 2). After being infiltrated with the slurry, the partially densified CMC 1000 may exhibit and possess an amount of particle loading 1400 within and at the surface of the partially densified CMC 1000 that may form the aforementioned microchannels 1500 (see FIG. 3). After being successivelyRTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOinfiltrated with slurries whose particles successively become smaller and smaller in average particle size, the partially densified CMC 1000 may exhibit and possess a desired maximum particle loading containing the fine particles 1600 distributed throughout microchannels formed by the coarse particles 1700 (see FIG. 4). As result of the exemplary slurry infiltration steps disclosed herein, the resultant particle infiltrated, partially densified CMC exhibits and possesses a more uniformly particle size distribution of coarse and fine particles throughout the aforementioned partially densified CMC that achieves a desired maximum particle loading.

[0066] Next, at an exemplary step 800 of FIG. 1, a molten infiltrant may be melt-infiltrated within the particle infiltrated, partially densified CMC to form an at least partially melt-infiltrated (Ml) CMC, a melt-infiltrated CMC, or an Ml CMC. Any melt infiltration technique capable of infiltrating one or more metals, metal alloys, metalloids, metalloid alloys, combinations thereof, and the like, may be suitable for use herein. In at least one embodiment, a suitable melt infiltration technique may melt-infiltrate one or more of the following: silicon and silicon alloys. In at least another embodiment, a suitable melt infiltration technique may melt-infiltrate one or more of the following silicides: Si, Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, and Y-Si.

[0067] Lastly, at an exemplary step 900 of FIG. 1, the CMC optionally may be heat-treated to react at least one or more metals, metal alloys, metalloids, metalloid alloys, aforementioned various particles, fiber protection coatings, combinations thereof, and the like, within the CMC.

[0068] While the present disclosure has been particularly described, in conjunction with specific preferred embodiments, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art in light of the foregoing description. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications and variations as falling within the true scope and spirit of the present disclosure.

Claims

RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOCLAIMSWhat is claimed is:

1. A method for fabricating a ceramic matrix composite, comprising the steps of:fabricating at least one ceramic fiber preform using at least one fiber or at least one fiber tow;optionally depositing an interface coating material on at least one fiber or at least one fiber tow to form at least one interface coated fiber or at least one interface coated fiber tow;depositing at least one structural support material on the at least one interface coated fiber or at least one interface coated fiber tow of the at least one ceramic fiber preform to form at least one partially densified ceramic matrix composite;optionally depositing a fiber protection material on the at least one partially densified ceramic matrix composite;infiltrating and filling at least one pore of the at least one partially densified ceramic matrix composite with at least one particle contained in a solvent to form at least one particle infiltrated, partially densified ceramic matrix composite;removing the solvent from the at least one particle infiltrated, partially densified ceramic matrix composite;repeating the infiltration and filling step and removal step until achieving a particle loading amount for the at least one partially densified ceramic matrix composite;melt infiltrating the at least one particle infiltrated, partially densified ceramic matrix composite to form an at least partially melt-infiltrated ceramic matrix composite; and optionally heat-treating the at least partially melt-infiltrated ceramic matrix composite to form a melt-infiltrated ceramic matrix composite.

2. The method of claim 1, wherein the at least one fiber or the least one fiber tow comprises one or more of the following: silicon carbide, carbon, aluminum oxide, and silicon nitride.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO3. The method of claim 1, wherein the at least one structural support material comprises one or more of the following: carbides, carbons, nitrides, and borides.

4. The method of claim 3, wherein the carbides comprise one or more of the following: silicon carbide and boron carbide.

5. The method of claim 3, wherein the carbons comprise at least pyrolytic carbon.

6. The method of claim 3, wherein the nitrides comprise at least silicon nitride or silicon nitro carbide.

7. The method of claim 1, wherein the at least one particle comprises one or more of the following: carbides, carbons, nitrides, borides, silicides, metals, and metalloids.

8. The method of claim 7, wherein the carbides comprise one or more of the following: boron carbides, zirconium carbides, hafnium carbides, tantalum carbides, niobium carbides, titanium carbides, molybdenum carbides, boron carbides, tungsten carbides, vanadium carbides, chromium carbides, ytterbium carbides, and yttrium carbides.

9. The method of claim 7, wherein the carbons comprise one or more of the following: pyrolytic carbon, graphite flake, graphite particle, graphite fiber, carbon nanotubes, carbon nanofibers, carbon nanoparticles, carbon nanowires, carbon nanoribbons, and diamond particles.

10. The method of claim 7, wherein the nitrides comprise one or more of the following: silicon nitrides, titanium nitrides, boron nitrides, zirconium nitrides, hafnium nitrides, niobium nitrides, tantalum nitrides, vanadium nitrides, ytterbium nitrides, and yttrium nitrides.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO11. The method of claim 7 , wherein the borides comprise one or more of the following: silicon borides, titanium borides, borides, zirconium borides, hafnium borides, niobium borides, tantalum borides, vanadium borides, ytterbium borides, and yttrium borides.

12. The method of claim 7, wherein the silicides comprise one or more of the following: Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, and Y-Si.

13. The method of claim 7, wherein the metals comprise one or more of the following: Zirconium, hafnium, tantalum, niobium, titanium, molybdenum, tungsten, vanadium, chromium, ytterbium, and yttrium.

14. The method of claim 7, wherein the metalloids comprise one or more of the following: boron and silicon.

15. The method of claim 1, wherein the melt infiltration step comprises melt-infiltrating one or more of the following: silicon and silicon alloys.

16. The method of claim 15, wherein the silicides comprise one or more of the following: Si, Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, and Y-Si.

17. The method of claim 1, wherein the optional heat-treating step comprises reacting at one or more of the following: transition metal, metal, metal alloy, metalloid, metalloid alloy; with one or more of the following: fiber protection material, at least one particle; within the at least partially infiltrated ceramic matrix.

18. The method of claim 1, wherein the at least one particle comprises at least one coarse particle and at least one fine particle.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO19. The method of claim 18, wherein the at least one coarse particle comprises an average particle size of approximately 1 pm to approximately 100 pm.

20. The method of claim 18, wherein the at least one fine particle comprises an average particle size of approximately 50 nm to approximately 5 pm.

21. The method of claim 1, wherein repeating the infiltration and filling step and removal step further comprises the following steps:infiltrating and filling the at least one pore with the solvent and at least one first particle having a first average particle size;removing the solvent;infiltrating and filling the at least one pore with the solvent and at least one second particle having a second average particle size; andremoving the solvent.

22. The method of claim 21, wherein the first average particle size is greater than the second average particle size.

23. The method of claim 21, wherein the second average particle size is less than the first average particle size.

24. A ceramic matrix composite fabricated according to a process comprising the steps of:fabricating at least one ceramic fiber preform using at least one fiber or at least one fiber tow;optionally depositing an interface coating material on at least one fiber or at least one fiber tow to form at least one interface coated fiber or at least one interface coated fiber tow;RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOdepositing at least one structural support material on the at least one interface coated fiber or at least one interface coated fiber tow of the at least one ceramic fiber preform to form at least one partially densified ceramic matrix composite;optionally depositing a fiber protection material on the at least one partially densified ceramic matrix composite;infiltrating and filling at least one pore of the at least one partially densified ceramic matrix composite with at least one particle contained in a solvent to form at least one particle infiltrated, partially densified ceramic matrix composite;removing the solvent from the at least one particle infiltrated, partially densified ceramic matrix composite;repeating the infiltration and filling step and removal step until achieving a particle loading amount for the at least one partially densified ceramic matrix composite;melt infiltrating the at least one particle infiltrated, partially densified ceramic matrix composite to form an at least partially melt-infiltrated ceramic matrix composite; and optionally heat-treating the at least partially melt-infiltrated ceramic matrix composite to form a melt-infiltrated ceramic matrix composite.

25. The ceramic matrix composite of claim 24, wherein the at least one fiber or the least one fiber tow comprises one or more of the following: silicon carbide, carbon, aluminum oxide, and silicon nitride.

26. The ceramic matrix composite of claim 24, wherein the at least one structural support material comprises one or more of the following: carbides, carbons, nitrides and borides.

27. The ceramic matrix composite of claim 26, wherein the carbides comprise one or more of the following: silicon carbide and boron carbide.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO28. The ceramic matrix composite of claim 26, wherein the carbons comprise at least pyrolytic carbon.

29. The ceramic matrix composite of claim 26, wherein the nitrides comprise at least silicon nitride or silicon nitro carbide.

30. The ceramic matrix composite of claim 27, wherein the at least one particle comprises one or more of the following: carbides, carbons, nitrides, borides, silicides, metals, and metalloids.

31. The ceramic matrix composite of claim 30, wherein the carbides comprise one or more of the following: boron carbides, zirconium carbides, hafnium carbides, tantalum carbides, niobium carbides, titanium carbides, molybdenum carbides, boron carbides, tungsten carbides, vanadium carbides, chromium carbides, ytterbium carbides, and yttrium carbides.

32. The ceramic matrix composite of claim 30, wherein the carbons comprise one or more of the following: pyrolytic carbon, graphite flake, graphite particle, graphite fiber, carbon nanotubes, carbon nanofibers, carbon nanoparticles, carbon nanowires, carbon nanoribbons, and diamond particles.

33. The ceramic matrix composite of claim 30, wherein the nitrides comprise one or more of the following: silicon nitrides, titanium nitrides, boron nitrides, zirconium nitrides, hafnium nitrides, niobium nitrides, tantalum nitrides, vanadium nitrides, ytterbium nitrides, and yttrium nitrides.

34. The ceramic matrix composite of claim 30, wherein the borides comprise one or more of the following: silicon borides, titanium borides, borides, zirconium borides, hafnium borides, niobium borides, tantalum borides, vanadium borides, ytterbium borides, and yttrium borides.RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WO35. The ceramic matrix composite of claim 30, wherein the silicides comprise one or more of the following: Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, and Y-Si.

36. The ceramic matrix composite of claim 30, wherein the metals comprise one or more of the following: Zirconium, hafnium, tantalum, niobium, titanium, molybdenum, tungsten, vanadium, chromium, ytterbium, and yttrium.

37. The ceramic matrix composite of claim 30, wherein the metalloids comprise one or more of the following: boron and silicon.

38. The ceramic matrix composite of claim 24, wherein the melt infiltration step comprises melt-infiltrating one or more of the following: silicon and silicon alloys.

39. The ceramic matrix composite of claim 38, wherein the silicides comprise one or more of the following: Si, Hf-Si, Zr-Si, Ti-Si, Ta-Si, Ir-Si, Mo-Si, W-Si, B-Si, Nb-Si, Yb-Si, V-Si, Sc-Si, and Y-Si.

40. The ceramic matrix composite of claim 24, wherein the optional heat-treating step comprises reacting one or more of the following: transition metal, metal, metal alloy, metalloid, metalloid alloy; with one or more of the following: fiber protection material, at least one particle; within the at least partially infiltrated ceramic matrix.

41. The ceramic matrix composite of claim 24, wherein repeating the infiltration and filling step and removal step further comprises the following steps:infiltrating and filling the at least one pore with the solvent and at least one first particle having a first average particle size;removing the solvent;RTX Ref. No.: 182233WO01MWZB Ref. No.: RTXPW-0069-WOinfiltrating and filling the at least one pore with the solvent and at least one second particle having a second average particle size; andremoving the solvent.

42. The ceramic matrix composite of claim 41, wherein the first average particle size is greater than the second average particle size.

43. The ceramic matrix composite of claim 41, wherein the second average particle size is less than the first average particle size.

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