The present disclosure relates to composites, and more specifically, to composites having ceramic particles and methods of forming the same.
Aircraft typically utilize brake systems on wheels to slow or stop the aircraft during landings, taxiing, and rejected takeoffs. Aircraft brake systems generally employ a brake stack (also referred to as a heat sink) comprising a series of friction disks that may be forced into contact with one another during braking to slow or stop the aircraft. The heat sink typically comprises rotor disks and stator disks that, in response to axial compressive pressure, convert the kinetic energy of the aircraft into heat through frictional forces experienced between the friction disks. Heat sinks comprising carbon fiber carbon matrix composite (C/C) components and/or carbon fiber ceramic matrix composite (CMC) components may prove advantageous in addressing frictional and wear performance.
Next generation heat sinks are expected to exhibit greater heat capacities in order to absorb and dissipate greater amounts of heat, particularly during rejected takeoffs. However, making a C/C and/or CMC component that has the needed strength and the needed specific heat (Cp) has proven difficult. Boron or boron carbide materials possess relatively high heat capacities and thermal stability. However, difficulties arise when attempting to incorporate boron or boron carbide materials into the carbon fiber structures used to form the C/C and CMC components, resulting in limitations on the size and amounts of the high heat capacity materials that may be incorporated into the carbon fiber structures.
Disclosed herein is a method of fabricating a composite component. In accordance with various embodiments, the method may comprise the steps of forming a fibrous preform and densifying the fibrous preform. The step of forming the fibrous preform may comprise the steps of forming a first ceramic particle layer over a first textile layer, disposing a second textile layer over the first ceramic particle layer, forming a second ceramic particle layer over the second textile layer, and disposing a third textile layer over the second ceramic particle layer.
In various embodiments, the method may further comprise the step of performing a silicon melt infiltration after the densifying the fibrous preform. In various embodiments, the step of forming the first ceramic particle layer may comprise depositing a first volume of boron carbide powder over the first textile layer, and the step of forming the second ceramic particle layer may comprise depositing a second volume of boron carbide powder over the second textile layer.
In various embodiments, the step of forming the fibrous preform may further comprise locating a first shim around an outer perimeter of the first textile layer, and locating a second shim around an outer perimeter of the second textile layer.
In various embodiments, the step of forming the fibrous preform may further comprise removing a portion of the first volume of boron carbide powder extending beyond an upper surface of the first shim, and removing a portion of the second volume of boron carbide powder extending beyond an upper surface of the second shim.
In various embodiments, the step of forming the fibrous preform may further comprise disposing the first textile layer on a first plate, and disposing a second plate over the third textile layer. In various embodiments, at least one of the first plate or the second plate may include at least one of a groove or an orifice. In various embodiments, the method may further comprise the step of applying a compressive load to the fibrous preform.
A method of forming a fibrous preform for fabricating a composite component is also disclosed herein. In accordance with various embodiments, the method may comprise the steps of forming a first ceramic particle layer over a first textile layer, disposing a second textile layer over the first ceramic particle layer, forming a second ceramic particle layer over the second textile layer, and disposing a third textile layer over the second ceramic particle layer.
In various embodiments, the method may further comprise the steps of disposing the first textile layer on a first plate, and disposing a second plate over the third textile layer. At least one of the first plate or the second plate may include at least one of a groove or an orifice.
In various embodiments, the step of forming the first ceramic particle layer may comprise depositing a first volume of boron carbide powder over the first textile layer, and the step of forming the second ceramic particle layer may comprise depositing a second volume of boron carbide powder over the second textile layer.
In various embodiments, the method may further comprise the steps of locating a first shim around an outer perimeter of the first textile layer, and locating a second shim around an outer perimeter of the second textile layer.
In various embodiments, the method may further comprise the steps of selecting the first volume of boron carbide powder such that the first volume of boron carbide powder extends at least to an upper surface of the first shim, and removing any portion of the first volume of boron carbide powder extending beyond the upper surface of the first shim. The upper surface of the first shim may be oriented away from the first plate.
In various embodiments, the method may further comprise the steps of disposing the first textile layer on a mold surface, forming the first ceramic particle layer by depositing a mixture of boron carbide powder and phenolic resin powder over the first textile layer, and curing the phenolic resin powder.
In various embodiments, at least one of the first textile layer, the second textile layer, or the third textile layer may comprise stretch-broken carbon fibers.
A fiber reinforced composite component is also disclosed herein. In accordance with various embodiments, the fiber reinforced composite component may comprise a first textile layer comprising a plurality of first carbon fibers, a second textile layer comprising a plurality of second carbon fibers and a layer of ceramic particles located between the first textile layer and the second textile layer. A carbon matrix material may encapsulate the plurality of first carbon fibers, the plurality of second carbon fibers, and the layer of ceramic particles. The carbon matrix material may define a plurality of pores. A silicon material may be located in the plurality of pores.
In various embodiments, the ceramic particles may comprise boron carbide. In various embodiments, a ratio of a weight of the boron carbide to a weight of the silicon material may be greater than or equal to 2.125:1.
In various embodiments, a weight percentage of the silicon material may be less than 6.0% of a total weight of the fiber reinforced composite component. In various embodiments, a weight percentage of the boron carbide may be between 20% and 60% of the total weight of the fiber reinforced composite component.
The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated herein otherwise. These features and elements as well as the operation of the disclosed embodiments will become more apparent in light of the following description and accompanying drawings.
The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the concluding portion of the specification. A more complete understanding of the present disclosure, however, may best be obtained by referring to the detailed description and claims when considered in connection with the drawing figures, wherein like numerals denote like elements.
The detailed description of exemplary embodiments herein makes reference to the accompanying drawings, which show exemplary embodiments by way of illustration. While these exemplary embodiments are described in sufficient detail to enable those skilled in the art to practice the disclosure, it should be understood that other embodiments may be realized and that logical changes and adaptations in design and construction may be made in accordance with this disclosure and the teachings herein without departing from the spirit and scope of the disclosure. Thus, the detailed description herein is presented for purposes of illustration only and not of limitation.
Provided herein, according to various embodiments, are fiber reinforced composite parts and method(s) for fabricating fiber reinforced composite parts, such as brake disks, having ceramic particle layers interspersed between textile layers. While numerous details are included herein pertaining to aircraft components, such as brake components, the components and method(s) disclosed herein can be applied to fabricate other carbon fiber-reinforced/carbon matrix composite (C/C) components that benefit from better wear performance and increased specific heat (Cp).
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Multi-disk brake assembly 20 includes a plurality of brake disks 38. The plurality of brake disks 38 includes at least one non-rotatable friction disk (stator disk) 40, and at least one rotatable friction disk (rotor disk) 42. Each of the brake disks 38 includes an attachment structure. In various embodiments, each of the stator disks 40 includes a plurality of stator lugs 44 at circumferentially spaced positions around an inner circumference of the stator disk 40 as an attachment structure. Similarly, each of the rotatable rotor disks 42 includes a plurality of rotor lugs 46 at circumferentially spaced positions around an outer circumference of the rotor disk 42.
Brake disks 38 may include an end plate 32 and a pressure plate 30 located on opposing axial ends of the brake disk stack. End plate 32 is connected to, or is otherwise frictionally engaged with, a reaction plate 34 of torque tube 24. End plate 32 is non-rotatable by virtue of its connection to torque tube 24. Stator splines 36 may support pressure plate 30 such that pressure plate 30 is also non-rotatable. Stator splines 36 may also support non-rotatable stator disks 40. Stator disks 40 may engage stator splines 36 with gaps formed between stator lugs 44. Similarly, rotor disks 42 may engage rotor splines 18 with gaps formed between rotor lugs 46. Rotor disks 42 may be rotatable by virtue of their engagement with rotor splines 18 of wheel 10.
An actuating mechanism for the multi-disk brake assembly 20 includes a plurality of piston assemblies 22 (one shown) circumferentially spaced around a piston housing 26. Upon actuation, the plurality of piston assemblies affects a braking action by urging pressure plate 30, stator disks 40, and end plate 32 into frictional engagement with rotor disks 42. Through compression of the plurality of rotor disks 42 and the plurality of stator disks 40 between the pressure plate 30 and the end plate 32, the resulting frictional contact slows or stops or otherwise prevents rotation of the wheel 10.
In various embodiments, one or more of the friction disks (e.g., rotor disks 42, stator disks 40, pressure plate 30, end plate 32) are fabricated from composite materials, such as, for example, C/C and/or CMC, that enable the brake disks to withstand and dissipate the heat generated during and following a braking action. In various embodiments, the non-rotating frictional components of multi-disk brake assembly 20 (i.e., pressure plate 30, end plate 32, and stator disks 40) may comprise a material that is different from the material of the rotating frictional component (e.g., rotor disks 42). For example, in various embodiments, rotor disks 42 comprise C/C and pressure plate 30, end plate 32, and/or stator disks 40 may comprise CMC. In various embodiments, rotor disks 42 and/or stator disks 40 may comprise a core made of a first material (e.g., CMC) and wear liners attached to the core that are made of a second, different material (e.g., C/C).
In accordance with various embodiments, one or more of the friction disks are comprised of a C/C material having high specific heat particles interspersed throughout the friction disk, where high specific heat particles includes any particle or powder (typically ceramic) that raises the specific heat of the disk above that of C/C alone. For example, in various embodiments, the friction disk may comprise a C/C that includes a percentage of boron, boron carbide (B4C), a boron component, or other material having a high specific heat (i.e., a specific heat greater than the specific heat of the C/C alone).
As described in further detail below, the process of interspersing the boron carbide (or other high specific heat particles) into the C/C is performed by depositing a boron carbide powder between one or more textile layers of the fibrous preform used to form the friction disk. After forming the fibrous preform, including one or more layers of boron carbide particles, the fibrous preform is densified using chemical vapor infiltration (CVI) and/or chemical vapor deposition (CVD). During densification, a matrix material (e.g., a carbon matrix) is deposited on and encapsulates the boron carbide particles and the fibers of the textile layers. In various embodiments, after densification, a silicon melt infiltration is performed to form a silicon layer over the carbon matrix. Depositing boron carbide powder between the textile layers may allow greater volumes of boron carbide (B4C) to be included in the composite part. Increasing the volume of boron carbide may decrease a porosity and/or increase a density of the final composite component. Further, greater volumes of B4C particles may reduce the volume of silicon material in the final composite component and/or may increase the specific heat of the final composite component.
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In accordance with various embodiments, textile layers 102 comprises woven, braided, or knitted carbon fibers. In various embodiments, one or more of the textile layers 102 may comprise carbon fibers in an open weave pattern (i.e., a weave wherein there is increased distance between the warp tows and between the weft tows). In various embodiments, one or more of the textile layers 102 may comprise stretch-broken carbon fibers. Employing stretch-broken carbon fibers tends to increase the bonding or securing of the ceramic particles (e.g., B4C) within the textile layer and the composite part. In various embodiments, the carbon fibers may be derived from polyacrylonitrile (PAN), rayon (synthetic fiber derived from cellulose), oxidized polyacrylonitrile fiber (OPF), carbon pitch, or the like. The starting fiber may be pre-oxidized PAN or fully carbonized commercial carbon fiber. The textile layers 102 may be formed or cut having any desired shape or form. For example, the textile layers 102 may have any shape such as, for example, a polygon, circular, triangle, square, rectangle, pentagon, hexagon, octagon, or any other desired shape. In various embodiments, textile layers 102 and fibrous preform 100 may have a generally annular shape.
Fibrous preform 100 is a lay-up of textile layers 102. In accordance with various embodiments, fibrous preform 100 includes one or more ceramic particle layers 104. Each ceramic particle layer 104 is located between a pair of adjacent textile layers 102. In various embodiments, ceramic particle layers 104 may be comprised of boron carbide particles. A range of particle sizes (or powder sizes) may be employed in the ceramic powders used to fabricate the ceramic particle layers 104. For example, in various embodiments, a boron carbide powder between 10 grit and 400 grit may be selected for ceramic particle layers 104. In various embodiments, a boron carbide powder between 100 grit and 400 grit may be selected for ceramic particle layers 104. In various embodiments, a boron carbide powder between 100 grit and 320 grit may be selected for ceramic particle layers 104. In various embodiments, a 240 grit boron carbide powder may be used to form ceramic particle layers 104. Stated differently, the boron carbide particles may have an average particle size between about 22 micrometers (μm) and about 1854 μm, between about 22 μm and about 122 μm, between about 31 μm and about 122 μm, and/or about 51 μm (i.e., between about 0.00047 inches and about 0.073 inches, between about 0.00047 inches and about 0.0048 inches, between about 0.00122 inches and about 0.0048 inches, and/or about 0.0020 inches). As used in the previous context only, the term “about” means plus or minus ten percent of the associated value.
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In accordance with various embodiments, a compressive load may be applied to fibrous preform 100. For example, in response to removing the shims, the weight of plate 150 may compress fibrous preform 100 between plate 110 and plate 150. In various embodiments, a compressive load may be applied to plate 150 to compress fibrous preform 100 between plate 110 and plate 150. In various embodiments, one or more clamps may be attached between plate 110 and plate 150. The clamps are configured to compress fibrous preform 100 between plate 110 and plate 150.
Fibrous preform 100 and plates 110, 150 are then placed in a CVI/CVD furnace for densification. After densification (i.e., once a desired density and/or a desired volume of carbon matrix is achieved), a silicon melt infiltration (SMI) may be performed to fill, or substantially fill, any remaining porosity (e.g., any pores in and/or defined by the matrix material).
In various embodiments, fibrous preform 100 may be fabricated using a net shape molding technology. For example, the textile layers 102 and ceramic particle layers 104 may be laid-up over a mold surface, rather than plate 110. During the lay-up process, the textile layers 102 of fibrous preform 100 conform to the shape of the mold surface. In various embodiments, the ceramic particle layers 104 may include a mixture of boron carbide powder and phenolic resin powder. The phenolic resin powder may form, for example, between 5% and 10%, between 0.5% and 5%, or less than 2%, by weight percentage, of the total boron-carbide-phenolic-resin powder mixture. Once the desired number of textile layers 102 and ceramic particle layers 104 have been stacked over the mold surface, the fibrous preform is cured. For example, the fibrous preform may be heated at a temperature of about 200° C. for between 1 and 10 hours. It will be appreciated that the cure temperature and time may be selected based on the particular type and volume of phenolic resin powder. Fabricating the fibrous preform using net shape molding technology may decrease manufacturing time and/or material waste, as the need to machine the part may be eliminated or reduced. After curing, the fibrous preform 100 is densified and a SMI is performed.
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In various embodiments, after densification and prior to SMI, fibrous preform 100 may have an open porosity of less than 15%, less than 10%, or less than 8%. In the regard, the open volume defined by the matrix material 212 may form less than 15%, less than 10%, or less than 8% of the total volume of densified fibrous preform 100. In various embodiments, after SMI, fiber-reinforced composite component 200 may have an open porosity of less than 2% or less than 1%. In this regard, the pores, or open volume, of fiber-reinforced composite component 200 may form less than 2% or less than 1% of the total volume of fiber-reinforced composite component 200. In various embodiments, the silicon material (e.g., the silicon 214 and the silicon in the silicon carbide 216) may form less than 10%, less than 8%, or less than 6% of a total mass of fiber-reinforced composite component 200.
In accordance with various embodiments, the volume of boron carbide powder in fiber-reinforced composite component 200 is selected such that a ratio of the mass of boron carbide to the mass of silicon in fiber-reinforced composite component 200 is at least 2.125:1. In various embodiments, the ratio of the mass of boron carbide to the mass silicon in fiber-reinforced composite component 200 may be between 2.125:1 and 15:1, between 2.125:1 and 5:1, between 2.125:1 and 3:1, or between 2.125:1 and 2.5:1. A ratio of 2.125:1 or greater is associated with an increased specific heat of fiber-reinforced composite component 200, relative to C/C alone. Increasing the ratio of boron carbide to silicon in fiber-reinforced composite component 200 tends to increase the specific heat of fiber-reinforced composite component 200. In this regard, the specific heat of fiber-reinforced composite component 200 may be tailored by increasing the volume boron carbide and/or decreasing the volume of silicon. In various embodiments, fiber-reinforced composite component 200 may include, by weight percentage, between 10% and 80% boron carbide, between 20% and 60% boron carbide, and/or between 50% and 60% boron carbide. Fiber-reinforced composite component 200 may thus be a exhibits similar properties (e.g., strength, ductility, reduced crack propagation, etc.) to C/C alone, but with an increased specific heat. Stated differently, fiber-reinforced composite component 200 is a CMC material having a greater specific heat than C/C, while exhibiting the other properties of C/C.
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Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. Furthermore, the connecting lines shown in the various figures contained herein are intended to represent exemplary functional relationships and/or physical couplings between the various elements. It should be noted that many alternative or additional functional relationships or physical connections may be present in a practical system. However, the benefits, advantages, solutions to problems, and any elements that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of the disclosure.
The scope of the disclosure is accordingly to be limited by nothing other than the appended claims, in which reference to an element in the singular is not intended to mean “one and only one” unless explicitly so stated, but rather “one or more.” It is to be understood that unless specifically stated otherwise, references to “a,” “an,” and/or “the” may include one or more than one and that reference to an item in the singular may also include the item in the plural. All ranges and ratio limits disclosed herein may be combined.
Moreover, where a phrase similar to “at least one of A, B, and C” is used in the claims, it is intended that the phrase be interpreted to mean that A alone may be present in an embodiment, B alone may be present in an embodiment, C alone may be present in an embodiment, or that any combination of the elements A, B and C may be present in a single embodiment; for example, A and B, A and C, B and C, or A and B and C. Different cross-hatching is used throughout the figures to denote different parts but not necessarily to denote the same or different materials.
The steps recited in any of the method or process descriptions may be executed in any order and are not necessarily limited to the order presented. Furthermore, any reference to singular includes plural embodiments, and any reference to more than one component or step may include a singular embodiment or step. Elements and steps in the figures are illustrated for simplicity and clarity and have not necessarily been rendered according to any particular sequence. For example, steps that may be performed concurrently or in different order are illustrated in the figures to help to improve understanding of embodiments of the present disclosure.
Any reference to attached, fixed, connected or the like may include permanent, removable, temporary, partial, full and/or any other possible attachment option. Additionally, any reference to without contact (or similar phrases) may also include reduced contact or minimal contact. Surface shading lines may be used throughout the figures to denote different parts or areas but not necessarily to denote the same or different materials. In some cases, reference coordinates may be specific to each figure.
Systems, methods, and apparatus are provided herein. In the detailed description herein, references to “one embodiment,” “an embodiment,” “various embodiments,” etc., indicate that the embodiment described may include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described. After reading the description, it will be apparent to one skilled in the relevant art(s) how to implement the disclosure in alternative embodiments.
Furthermore, no element, component, or method step in the present disclosure is intended to be dedicated to the public regardless of whether the element, component, or method step is explicitly recited in the claims. No claim element is intended to invoke 35 U.S.C. 112(f) unless the element is expressly recited using the phrase “means for.” As used herein, the terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.
This application claims priority to, and the benefit of, U.S. Provisional Application Ser. No. 63/039,092, filed Jun. 15, 2020 and titled “COMPOSITES AND METHODS OF FORMING COMPOSITES HAVING AN INCREASED VOLUME OF CERAMIC PARTICLES,” which is incorporated by reference herein in its entirety for all purposes.
Number | Date | Country | |
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63039092 | Jun 2020 | US |