Methods and apparatus for crosslinking a silicon carbide fiber precursor polymer

The present disclosure generally provides methods and apparatus for efficiently crosslinking silicon carbide fiber precursor polymers with electron beam radiation. The methods and apparatus utilize a platform containing silicon carbide fiber precursor polymer. The temperature of the platform is regulated while the silicon carbide fiber precursor polymer is irradiated to thereby regulate the temperature of the irradiated silicon carbide fiber precursor polymer thereon. In this way, the temperature of the irradiated silicon carbide fiber precursor polymer is regulated via the platform both during and after it is subjected to radiation. At least one of the platform and the e-beam radiation mechanism may be translated with respect to the other to irradiate different portions of the silicon carbide fiber precursor polymer and, ultimately, the entirety of the silicon carbide fiber precursor polymer contained on the platform.

BACKGROUND

The present invention generally relates to methods and apparatus for crosslinking a silicon carbide fiber precursor polymer. More particularly, the present invention relates to methods and apparatus for efficiently crosslinking a silicon carbide fiber precursor polymer by e-beam radiation.

Silicon carbide (SiC) is one of several advanced ceramic materials which are currently receiving considerable attention as electronic materials, as potential replacements for metals in engines, and for a variety of other applications where high strength, combined with low density and resistance to oxidation, corrosion and thermal degradation at high temperatures is desirable or necessary. Unfortunately, these extremely hard, non-melting ceramics are difficult to process by conventional forming, machining, or spinning applications rendering their use for many of these potential applications problematic. In particular, crosslinking SiC fiber polymer precursors (polycarbosilane and polydisilazane) via e-beam irradiation is the biggest bottleneck in the silicon carbide fiber production process.

Crosslinking SiC fiber polymer precursors (e.g., polycarbosilane and polydisilazane) makes the polymer infusible, so the fiber's dimensional integrity will be maintained during subsequent pyrolysis. Currently, e-beam is the typical mechanism used to effectuate the crosslinking of SiC fiber polymer precursors. However, the throughput of the current crosslinking process is severely limited by temperature increase incurred by the fibers due to the energy absorbed during irradiation. As a result, the radiation dose must be delivered at a rate slow enough to ensure that the SiC fiber polymer precursors do not reach their melting point, and thus lose their shape and/or fuse together.

In typical arrangements the radiation dose is regulated or limited through the use of a conveyor system. After a portion of a preceramic SiC fiber is irradiated, it rides around a long conveyor to cool down in the ambient atmosphere before returning to the e-beam for another small dose of radiation. The portions of the preceramic SiC fiber are passed under the e-beam enough times to receive the cumulative dose needed for effective crosslinking—thereby crosslinking the entire length of the fiber. When large doses (several MGy) are required to effectively crosslink a polymer fiber the radiation process becomes prohibitively expensive due to the large capital investment required in very long conveyor systems and long production times.

Thus, a need exists for methods and apparatus for efficiently crosslinking SiC fiber polymer precursors (e.g., polycarbosilane and polydisilazane) via e-beam while maintaining the fiber's dimensional integrity. Methods and apparatus facilitating e-beam curing of such fibers at much higher rates than prior art methods and apparatus would provide for valuable high throughput, cost-effective commercial silicon carbide fiber production with reduced footprint requirements.

BRIEF DESCRIPTION

In one aspect, a method of crosslinking a silicon carbide fiber precursor polymer is disclosed. The method includes exposing a first portion of silicon carbide fiber precursor polymer provided on a platform to e-beam radiation from an e-beam radiation mechanism. The method also includes translating at least one of the platform and the e-beam radiation with respect to the other and exposing a second portion of the silicon carbide fiber precursor polymer to e-beam radiation. The method further includes regulating the temperature of the platform to thereby prevent the temperature of the first and second portions of the carbide fiber precursor polymer from reaching their softening point due to the e-beam radiation.

In another aspect, an apparatus for crosslinking a silicon carbide fiber precursor polymer with electron beam radiation is disclosed. The apparatus includes a platform including a processing surface and a coolant channel. The apparatus also includes multiple layers of silicon carbide fiber precursor polymer positioned on the processing surface of the platform. In some embodiments, the coolant channel is configured to regulate the temperature of the processing surface and thereby the temperature of the multiple layers of silicon carbide fiber precursor polymer positioned thereon during crosslinking through the use of heat transfer fluid.

In another aspect, an apparatus for crosslinking a silicon carbide fiber precursor polymer is disclosed. The apparatus includes a platform, a translation mechanism, and an e-beam radiation mechanism configured to project e-beam radiation. The platform includes a processing surface, multiple layers of silicon carbide fiber precursor polymer positioned on the processing surface, and a coolant channel extending through the platform. The translation mechanism is configured to translate at least one of the platform and e-beam radiation projected from the e-beam radiation mechanism with respect to the other such that at a first configuration the e-beam radiation mechanism applies a first dose of e-beam radiation to a first portion of the silicon carbide fiber precursor polymer, and at a second configuration the e-beam radiation mechanism applies a first dose of e-beam radiation to a second portion of the silicon carbide fiber precursor polymer.

These and other objects, features, and advantages of this disclosure will become apparent from the following detailed description of the various aspects of the disclosure taken in conjunction with the accompanying drawings.

DETAILED DESCRIPTION

Each embodiment presented below facilitates the explanation of certain aspects of the disclosure, and should not be interpreted as limiting the scope of the disclosure. Moreover, approximating language, as used herein throughout the specification and claims, may be applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” is not limited to the precise value specified. In some instances, the approximating language may correspond to the precision of an instrument for measuring the value. When introducing elements of various embodiments, the articles “a,” “an,” “the,” and “said” are intended to mean that there are one or more of the elements. The terms “comprising,” “including,” and “having” are intended to be inclusive and mean that there may be additional elements other than the listed elements. As used herein, the terms “may” and “may be” indicate a possibility of an occurrence within a set of circumstances; a possession of a specified property, characteristic or function; and/or qualify another verb by expressing one or more of an ability, capability, or possibility associated with the qualified verb. Accordingly, usage of “may” and “may be” indicates that a modified term is apparently appropriate, capable, or suitable for an indicated capacity, function, or usage, while taking into account that in some circumstances, the modified term may sometimes not be appropriate, capable, or suitable. Any examples of operating parameters are not exclusive of other parameters of the disclosed embodiments. Components, aspects, features, configurations, arrangements, uses and the like described, illustrated or otherwise disclosed herein with respect to any particular embodiment may similarly be applied to any other embodiment disclosed herein.

The term “preceramic SiC fiber” (and its grammatical variations) is used herein to refer to silicon carbon (SiC) fiber polymer precursors or silicon carbon green fibers with or without some percentage of crosslinking

The methods and apparatus of the present disclosure provide for crosslinking silicon carbide (SiC) fiber polymer precursors (e.g., polycarbosilane and polysilazane) via e-beam irradiation at much higher rates than can be achieved by current state of the art. In some embodiments, the polysilazane is polydisilazane. The methods and apparatus disclosed herein may be capable of producing at least about 20 tons per year crosslinked preceramic SiC fiber, and more preferably at least about 30 tons per year crosslinked preceramic SiC fiber, using a single e-beam installation. Such production rates of crosslinked preceramic SiC fiber provide at least about 500% performance advantage over current typical SiC fiber polymer precursors e-beam apparatus and methods. In some embodiments, testing has resulted in a 600% increase in throughput of crosslinked preceramic SiC fiber as compared to typical preceramic SiC fiber crosslinking e-beam apparatus and methods. The preceramic SiC fiber or SiC fiber polymer precursor crosslinking methods and apparatus of the present disclosure also provide for greater radiation dose uniformity to the processed or crosslinked preceramic SiC fibers as compared to typical bulk containers in conveyor systems. Still further, the preceramic SiC fiber or SiC fiber polymer precursor crosslinking methods and apparatus of the present disclosure provide for lower operating temperatures of the preceramic SiC fiber during the crosslinking process at the same radiation dose rate as compared to prior preceramic SiC fiber polymer precursors crosslinking apparatus and methods. In yet another aspect, the preceramic SiC fiber crosslinking methods and apparatus of the present disclosure provide for lower capital investment (e.g., fewer e-beam units, less infrastructure, smaller footprint, etc.) as compared to prior SiC fiber polymer precursors crosslinking apparatus and methods.

In one aspect, the methods and apparatus of the present disclosure provide active temperature regulation or maintenance to a platform on/in which SiC fiber polymer precursors are provided and subjected to e-beam radiation. In this way, the temperature regulation of the platform actively and continuously regulates the preceramic SiC fiber provided thereon (e.g., through conduction) both during and after e-beam radiation. During crosslink processing, the absorbed radiation produces heat in the preceramic SiC fiber, and the temperature regulation includes cooling the platform to thereby cool the partially crosslinked preceramic SiC fiber. The temperature regulation may be effective in maintaining the temperature of the preceramic SiC fiber below the softening point of the polymer precursor. The radiation process may include irradiating a first portion of SiC fiber polymer precursors provided on the platform. Movement of the platform and/or the radiation mechanism emitting the e-beam radiation may cause a second portion of the SiC fiber polymer precursors to be irradiated, and the first portion to no longer be subjected to radiation. As heat may be continuously withdrawn from the platform and, thereby, the preceramic SiC fibers, higher dose rates of e-beam radiation can be achieved during the crosslink process. Further, the temperature regulation of the preceramic SiC fibers via the platform can increase throughput as compared to prior art crosslinking methods and apparatus. The methods and apparatus of the present disclosure thereby eliminate the need for the cooling conveyor system, and thereby decreases investment cost and required footprint, associated with prior art preceramic SiC fiber crosslinking methods and apparatus.

Exemplary apparatus, systems, methods and the like for crosslinking preceramic SiC fiber is illustrated inFIGS. 1-3Band referenced generally by reference numeral10. As shown inFIG. 1, the preceramic SiC fiber crosslinking apparatus and methods10may include several components, features and the like. The exemplary SiC fiber polymer precursor crosslinking apparatus and methods10shown inFIG. 1includes an e-beam emitting mechanism12, fiber platform14, preceramic SiC fiber16, and a translation mechanism18.

The e-beam emitting mechanism12may be any mechanism effective in emitting at least one dose of e-beam radiation to the preceramic SiC fiber16provided on/in the platform14. The beam current and electron energy metrics of the doses of e-beam radiation20emitted from the e-beam emitting mechanism12may be effective in at least partially crosslinking the SiC fiber polymer precursor16, and thereby may depend upon, or at least be related to, a number of variables. For example, the physical properties of the SiC fiber polymer precursor16(e.g., softening point, melting point, etc.), the pile thickness and or arrangement of the preceramic SiC fiber16on the platform14, the relative translation speed and orientation between the preceramic SiC fiber16and the e-beam radiation20, the level or effectiveness of the temperature maintenance or cooling provided by the platform14, the number of doses of e-beam radiation applied to the preceramic SiC fiber16, and the desired level of crosslinking are some factors or variables that may affect the minimum, maximum or most effective dose of e-beam radiation20emitted from the e-beam emitting mechanism12during a crosslinking process.

In some embodiments, the e-beam emitting mechanism12(in combination with other components of the apparatus10) may be configured to emit e-beam radiation at an accumulated dose between about 0.2 MGy and about 20 MGy, and preferably between about 5 MGy and about 20 MGy, depending upon the particular polymer of the preceramic SiC fiber16. With preceramic SiC fiber16embodiments utilizing polydisilazane as the polymer, the e-beam emitting mechanism12(in combination with other components of the apparatus10) may be configured to emit e-beam radiation20at an accumulated dose within the range of about 0.2 MGy to about 2 MGy. With preceramic SiC fiber16embodiments utilizing polycarbosilane as the polymer, the e-beam emitting mechanism12(in combination with other components of the apparatus10) may be configured to emit e-beam radiation20at accumulated doses greater than 5 MGy if the precursor to SiC fiber16is polycarbosilane, and preferably within the range of about 10 MGy to about 20 MGy.

In some embodiments, the precursor to SiC fiber16is positioned in a pile of two or more layers on the platform14. In some such embodiments, the thickness of the preceramic SiC fiber or SiC fiber polymer precursor16on the platform14is less than or equal to about one inch. In some such embodiments, the thickness of the preceramic SiC fiber16on/in platform14is less than or equal to about 0.5 inch. In some embodiments, the thickness of the preceramic SiC fiber16provided on/in the platform14is measured along the direction of the e-beam radiation20that intersects the preceramic SiC fiber16. In some embodiments, the apparatus may be configured such that the e-beam radiation20intersects the preceramic SiC fiber16in a substantial normal or perpendicular orientation.

As mentioned above, the relative speed and orientation between the preceramic SiC fiber16and the e-beam radiation20of the SiC fiber polymer precursor crosslinking apparatus10may affect, or at least be related to, the minimum, maximum or most effective dose of e-beam radiation20emitted from the e-beam emitting mechanism12during a crosslinking process. As shown inFIG. 1, the SiC fiber polymer precursor crosslinking apparatus and methods10may include a translation mechanism18. The translation mechanism18may be configured to translate at least one of the platform14(with the preceramic SiC fiber16contained therein/thereon) and the e-beam radiation20with respect to the other such that differing portions of the preceramic SiC fiber16receive a dose of e-beam radiation20(e.g., the entirety of the preceramic SiC fiber16on/in the platform14receives substantially the same dose of doses or e-beam radiation20). In some embodiments the translation mechanism18may be configured to translate the e-beam radiation20with respect to the platform14and the SiC fiber16carried thereon/therein. In some such embodiments, a portion or aspect of the e-beam emitting mechanism12may be translated by the translation mechanism18. In some embodiments, e-beam radiation20emitted from the e-beam emitting mechanism12may be translated by the translation mechanism18. For example, the translation mechanism18may be apply an electric/magnetic field to the e-beam radiation20emitted from the e-beam emitting mechanism12in order to translate the e-beam radiation20with respect to the preceramic SiC fiber16.

In some embodiments, the platform14carrying the preceramic SiC fiber16may be translated by the translation mechanism18with respect to the e-beam radiation20emitted from the e-beam emitting mechanism12, as shown inFIGS. 2A and 2B. Specifically, the crosslinking apparatus10may be configured such that, initially, the platform14carrying the preceramic SiC fiber16is translated from a first positioned where the green fiber16does not receive e-beam radiation20emitted from the e-beam emitting mechanism12to a second positioned where at least a first portion16A of the preceramic SiC fiber16receives a first dose of e-beam radiation20A, as shown inFIGS. 2A and 2B. Such translation may be linear, arcuate, rotational, or any other type or direction of movement that is effective in positioning the preceramic SiC fiber16in a position to receive e-beam radiation20emitted from the e-beam emitting mechanism12. In some embodiments, the size, shape, orientation, layout, pattern, etc of the emitted e-beam radiation20A may be smaller than the size, shape, orientation, layout, pattern, etc of the preceramic SiC fiber16that receives the radiation20—i.e., only a first portion16A of the preceramic SiC fiber16at a first point in time may be exposed to e-beam radiation20A during the crosslinking process, as shown inFIGS. 2A and 2B. For example, the e-beam emitting mechanism12may be configured to emit e-beam radiation20in a pattern that defines a smaller area as compared to the area of the preceramic SiC fiber16on the platform14that the radiation20intersects.

During the crosslinking process, the platform14carrying the green or preceramic SiC fiber16may be translated by the translation mechanism18with respect to the e-beam radiation20emitted from the e-beam emitting mechanism12to expose a second portion16B of the preceramic SiC fiber16to a dose of e-beam radiation20B. In this way, the translation mechanism18may be effective in exposing the entirety (or a portion) of the preceramic SiC fiber16to doses of e-beam radiation20from the e-beam emitting mechanism12. Multiple passes of the e-beam radiation20from the e-beam emitting mechanism12over the preceramic SiC fiber16thereby results in multiple doses of radiation20. As discussed further below, the temperature maintenance feature of the crosslinking apparatus and methods10allows for relatively rapid delivery of high doses of radiation20.

Translating at least one of the platform14containing the green fiber16and the e-beam radiation20with respect to the other, such that multiple portions of the preceramic SiC fiber16receive at least one dose of radiation20(i.e., the preceramic SiC fiber16is crosslinked), may be performed at a constant speed or at a variable speed. For example, the arrangement or orientation of the preceramic SiC fiber16on the platform14(e.g., constant pile thickness) may dictate that a constant translation speed between the preceramic SiC fiber16and the e-beam radiation20via the translation mechanism18would result in substantially uniform doses of radiation throughout the preceramic SiC fiber16. However, other arrangements or orientations of the preceramic SiC fiber16on the platform14may dictate that a variable translation speed between the preceramic SiC fiber16and the e-beam radiation20via the translation mechanism18would result in substantially uniform doses of radiation throughout the preceramic SiC fiber16. In still other variations, non-uniform doses of radiation to the preceramic SiC fiber16may be desirable and achieved, at least in part, by the speed or path of the relative translation between the preceramic SiC fiber16and the e-beam radiation20via the translation mechanism18. In some embodiments, the translation mechanism18is configured to translate at least one of the platform14containing the preceramic SiC fiber16and the e-beam radiation20with respect to the other such that the translation speed between the preceramic SiC fiber16and the e-beam radiation20is substantially constant and relatively great. In some embodiments, the translation speed between the preceramic SiC fiber16and the e-beam radiation20may be at least about 100 cm/min. In some embodiments, the translation speed between the preceramic SiC fiber16and the e-beam radiation20may be at least about 500 cm/min.

The translation of the preceramic SiC fiber16(via the platform14) by the translation mechanism18during the crosslinking process may be linear, arcuate, rotational or any other type or direction of movement that is effective in positioning the preceramic SiC fiber16(via the platform14) in a position such a second portion16B of the preceramic SiC fiber16is irradiated, as indicated by the exemplary directional arrows emanating about the portion of the platform14shown inFIGS. 2A and 2B. In the embodiment shown inFIGS. 2A and 2B, the preceramic SiC fiber16is positioned on a substantially planar surface of the platform14. In such an embodiment, as shown inFIG. 2A, the translation mechanism18may be configured to translate the platform14, and thereby the preceramic SiC fiber16thereon, along a substantially linearly plane or direction22. By translating the platform14, and thereby the preceramic SiC fiber16thereon, back and forth along the substantially linearly plane or direction22, the translation mechanism18can be effective in irradiating the entirety of the preceramic SiC fiber16with several doses of the e-beam radiation20.

Another example of potential green or preceramic SiC fiber16layout on the platform14and the relative translation between the e-beam radiation20emitted from the e-beam emitting mechanism12and the platform14(and thereby the preceramic SiC fiber16thereon), is shown inFIG. 2B. As shown inFIG. 2B, in some embodiments the preceramic SiC fiber16may be positioned on a surface of the platform14in an arcuate, circular or spiral arrangement in one or more layers about an axis X-X that passes through the platform14. Similarly, in some embodiments the translation mechanism18may be configured to translate the platform14, and thereby the preceramic SiC fiber16thereon, in a rotational direction24about the X-X. Rotational movement24of the platform14, and thereby the preceramic SiC fiber16thereon, via the translation mechanism18can be effective in irradiating the entirety of the preceramic SiC fiber16with several doses of the e-beam radiation20(one dose per revolution). In some such embodiments, the central area of the platform14about the axis of rotation X-X may not include preceramic SiC fiber16thereon as such preceramic SiC fiber16would receive substantially higher doses of radiation20than portions distal the axis of rotation X-X. In some such embodiments, the crosslinking apparatus and methods10may be configured such that the axis of rotation X-X of the platform14, and thereby the preceramic SiC fiber16, may be substantially parallel with the direction of the e-beam radiation20.

An exemplary construction or arrangement of the green or preceramic SiC fiber platform14is shown inFIGS. 1, 3A and 3B. As shown inFIG. 1, the platform14may form or include a chamber30for containing the green SiC fiber16being processed (i.e., irradiated and thereby crosslinked). The chamber30may be substantially sealable or sealed such that the passage or migration of moisture and oxygen into the chamber30, and thereby onto or about the preceramic SiC fiber16contained therein, is substantially prevented during processing. In some embodiments, the chamber30may be configured such that moisture and oxygen contained therein is less than or equal to about 50 ppm during processing to avoid significant reaction with the radicals. In some embodiments, the chamber30may be configured such that oxygen contained therein is less than or equal to about 10 ppm during processing. In some embodiments the chamber30is substantially hermetically sealable or sealed.

The chamber30may be formed, at least in part, by a flange32, window member34, seal member36and base38, as shown inFIG. 1. The flange32may form an opening through which the e-beam radiation20may be projected and, ultimately, absorbed by the preceramic SiC fiber14. The flange32may also be utilized, at least in part, to couple a window member30over the opening. The window member30may be any material or arrangement that is penetrable by e-beam radiation20at levels that are effective in crosslinking the preceramic SiC fiber14contained within the chamber30. The window member30may also be any material or arrangement that is configured to substantially prevent the passage or migration of moisture and oxygen therethrough and thereby into the chamber and onto or about the SiC fiber16during crosslinking In some embodiments, the window member34is titanium foil. In some such embodiments, the titanium foil is about 2 mil thick.

In some embodiments, as shown inFIG. 1, the preceramic SiC fiber platform14may include at least one seal member36to ensure moisture and oxygen is substantially prevented from penetrating or migrating into the chamber30during processing (i.e., crosslinking) For example, at least one seal member36may be utilized to seal, at least in part, the window member30to the flange32and/or a base38. The base38may include a recessed treatment surface39(or other feature) configured to provide a space between the base38and the window member34when the flange32and window member34are coupled to the base38, as shown inFIG. 1. In this way, the treatment surface39may be configured to receive the preceramic SiC fiber16thereon. As also shown inFIG. 1, at least the flange32and base38may include corresponding apertures40A and40B, respectively, which facilitate coupling of the flange32, window member34, seal member36and base38to form the chamber30via fasteners (not shown). Further, the base38may include one or more port42configured for the removal of moisture and oxygen of the chamber30once the chamber30is sealed. For example, the at least one port42may be utilized to evacuate any moisture and oxygen from the chamber30after sealing, and/or to introduce an environment into the chamber30that facilities, or at least does not interfere with, crosslinking of the preceramic SiC fiber16. For example, the at least one port42may be utilized to evacuate moisture and oxygen from the chamber30such that the chamber30contains less than or equal to about 50 ppm moisture and oxygen, and preferably less than or equal to about 10 ppm of oxygen, during processing (e.g., irradiation). Once moisture and oxygen are substantially removed from the chamber30(and/or an environment is put into the chamber30), the at least one port42may be substantially sealed (e.g., hermetically sealed) to thereby seal the substantially oxygen and moisture free chamber30.

As shown inFIG. 3A, the base38may include a coolant inlet44, a coolant outlet46and a coolant channel48extending therebetween. The coolant inlet44, coolant outlet46and a coolant channel48may allow heat transfer material or coolant (not shown) to flow through the base38. In the exemplary embodiment shown inFIGS. 1-3B, the base38is of two-part construction including a first bottom portion52and a second top portion54. The exemplary second top portion54includes or forms the treatment surface39one side, and includes or forms a portion of the coolant inlet44, coolant outlet46and a coolant channel48on an opposing side, as shown inFIG. 3A. In such an arrangement, heat transfer material or coolant flowing through the coolant channel48can absorb heat conducting through the second top portion54(and potentially the first bottom portion52) from the treatment surface39and, ultimately, from the irradiated preceramic SiC fiber16to maintain the temperature thereof during crosslinking When assembled, as shown inFIG. 3B, the first bottom portion52and the second top portion54may form a seal56therebetween such that a sealed coolant channel is formed through the base39(except for the inlet44and outlet46). In some embodiments, the heat transfer material or coolant may be a coolant fluid. One or more pump or like mechanism (not shown) may be associated with the platform14to force the flow of the heat transfer material or coolant through the coolant channel48of the platform14from the coolant inlet44to the coolant outlet46. In this way, the platform14(or apparatus or methods10) includes an integrated heat exchanger that maintains or regulates the temperature of the preceramic SiC fiber16on the platform concurrently with the doses of e-beam radiation20during the crosslinking process (i.e., both during doses of radiation and after each dose of radiation).

The coolant channel48, and coolant flowing therein during crosslinking, allows for relatively high dose rates of the e-beam radiation20to be applied without melting the preceramic SiC fiber16. In some embodiments, the coolant channel48, and coolant flowing therein, may be configured to maintain or regulate the temperature of the preceramic SiC fiber16below the softening point of the preceramic SiC fiber16during relatively high dose rates of e-beam radiation20(e.g., greater than or equal to about 12 kGy/sec) by maintaining or cooling the temperature of a portion of the platform14(e.g., via conduction, convection, or a combination thereof). As such, in some embodiments the temperature of heat transfer material or coolant flowing through the coolant channel48may be below the softening point of the preceramic SiC fiber16provided on the platform14. In some embodiments, the coolant channel48, and coolant flowing therein, may be configured to maintain or regulate the temperature of the preceramic SiC fiber16below the melting point of the preceramic polymer during relatively high dose rates of e-beam radiation20(e.g., greater than or equal to about 12 kGy/sec) by maintaining or cooling the temperature of a portion of the platform14(e.g., via conduction, convection, or a combination thereof). In some embodiments, the temperature of coolant flowing through the coolant channel48is at least about 50° C. below the softening point of the preceramic SiC fiber16within the chamber30of the platform14. In some embodiments, the platform14includes polysilazane SiC fiber16, and the coolant flowing through the coolant channel48is configured (e.g., temperature, flow rate, etc.) to maintain or prevent the temperature of the polysilazane SiC fiber16from exceeding about 100° C. In some embodiments, the platform14includes polycarbosilane SiC fiber16, and the coolant flowing through the coolant channel48is configured (e.g., temperature, flow rate, etc.) to maintain or prevent the temperature of the polycarbosilane SiC fiber16from exceeding about 200° C.

Another exemplary apparatus, systems, methods and the like for crosslinking preceramic SiC fiber is illustrated inFIGS. 4-5Band referenced generally by reference numeral110. As shown inFIGS. 4-5B, the preceramic SiC fiber crosslinking apparatus and methods110may include several components, features and the like that function similar to the exemplary preceramic SiC fiber crosslinking apparatus, system, method and the like10described above with reference toFIGS. 1-3Band therefore like reference numerals preceded by the numeral “1” are used to indicate like elements, configurations, features, functions and the like. The description above with respect to other preceramic SiC fiber crosslinking apparatus, systems, methods, features, functions and the like, and subassemblies thereof, including description regarding alternative embodiments (i.e., modifications, variations or the like), equally applies to the preceramic SiC fiber crosslinking apparatus, systems, methods and the like110(and any alternative embodiments thereof). As shown inFIGS. 4-5B, inter alia, the exemplary preceramic SiC fiber crosslinking apparatus, systems, methods and the like110ofFIGS. 4-5Bdiffers from the embodiments10ofFIGS. 1-3Bwith respect to the configuration or arrangement of the preceramic SiC fiber platform114, the preceramic SiC fiber116provided on the platform114, and the translation of the preceramic SiC fiber platform114(and thereby the preceramic SiC fiber116provided thereon) and/or the e-beam radiation120during the crosslinking process.

As shown inFIG. 4, the preceramic SiC fiber crosslinking apparatus and methods110are configured to crosslink (i.e., irradiate) the preceramic SiC fiber116provided on the platform114via rotation124of the platform114about an axis of rotation X-X by the translation mechanism118. The processing surface139of the base138of the platform114carrying the preceramic SiC fiber116thereon is formed about, and potentially defines, the axis of rotation X-X. For example, the base138may form or include a drum, spool, cylinder or like shape such that the processing surface139is arcuate and extends, at least partially, about the axis of rotation X-X, as shown inFIGS. 4 and 5A. In some embodiments, the base138(and/or the processing surface139thereof) forms an axis, and such axis may be substantially aligned with the axis of rotation X-X of the processing surface139. In some embodiments, the processing surface139of the base138of the platform forms a cylindrical shape with a diameter within the range of about 3 inches to about 10 feet, and preferably within the range of about 6 inches to about 3 feet. As shown inFIGS. 4 and 5B, in some embodiments the flange132and window member134may form a drum, spool, cylinder or like shape such that the flange132couples, at least in part, the window member134about the arcuate processing surface139of the base138. In this way, the flange138and window member134may seal, at least partially, the preceramic SiC fiber116to the base138.

The platform114may include an inner area that includes a cooling channel148for the flow of heat transfer material or coolant therethrough, as shown inFIG. 5A. In some embodiments, the cooling channel148may be defined by a conduit or other member or configuration effective in acting as a passageway for the coolant to flow therethrough from an inlet to an outlet. The cooling channel148may be configured to maintain, regulate or cool the processing surface139of the base138of the platform114, and thereby the preceramic SiC fiber116provided on the processing surface139. In some embodiments, the processing surface139of the base138of the platform114may be formed on an outer surface of a wall of the base138, and the cooling channel148may be provided on an inner surface of the wall of the base138opposing the outer surface. In this way, heat may travel via conduction (and/or another heat transfer mechanism) from the processing surface139and through the wall of the base138to the inner surface and, eventually, to the coolant flowing through the cooling channel148.

In some embodiments, as shown inFIGS. 4-5B, a cap member152may be coupled to the base138. The cap member152may enclose an inner portion of the base138, such as an inner portion including the cooling channel148. The cap member152may provide for the sealing of the flange138and window member134over the preceramic SiC fiber116to create a sealed chamber or cavity for the preceramic SiC fiber116. As noted above, the preceramic SiC fiber chamber, enclosure or cavity of the platform114for containing the preceramic SiC fiber116may be substantially hermetic, and may include one or more port to facilitate removal of moisture and oxygen from the chamber (and/or to introduce an environment into the chamber). As also shown inFIGS. 4-5B, a translation member150may be associated with the cap member152and the base138. The at least one translation member150may be configured to be utilized by the translation mechanism118to translate (e.g., rotate) the platform114(and thereby the preceramic SiC fiber116thereon) about the axis of rotation X-X.

As shown inFIG. 5A, the processing surface139of the drum-like base138of the platform114may be wound with preceramic SiC fiber116. In some embodiments, the preceramic SiC fiber116on the platform114may be wound directly from a spinneret of a fiber spinning line. The preceramic SiC fiber116may be wound to form a pile of multiple layers of preceramic SiC fiber116. In some such embodiments, the thickness of the preceramic SiC fiber116of platform114may be less than or equal to about one inch. In some embodiments, the thickness of the preceramic SiC fiber116of platform114may be about 0.8 inch.

Once the platform114is wound with preceramic SiC fiber116, the cap member152and/or translation member150may be coupled to the base138of the platform114, as shown inFIG. 5A. Once the cap member152is coupled to the platform114wound with SiC fiber116, the flange132and window member134may be coupled to the platform114to form a substantially sealed area, cavity, enclosure or chamber about the preceramic SiC fiber116. As noted above, the sealed area, cavity, enclosure or chamber about the preceramic SiC fiber116may be substantially evacuated of oxygen and/or moisture. Further, one or more ports may be utilized to introduce an environment into the sealed area, cavity, enclosure or chamber about the preceramic SiC fiber116that facilities crosslinking of the preceramic SiC fiber116via e-beam radiation120. As shown inFIG. 4, the sealed platform114may be translated in a direction122such that e-beam radiation120emitted from the e-beam radiation mechanism112passes through the window member134and intersects the preceramic SiC fiber116. In some embodiments, such translation of the platform114may be provided by the translation mechanism118. As also shown inFIG. 4, in some embodiments the e-beam radiation mechanism112and the platform114may be arranged or oriented such that e-beam radiation120extends over the entirety, or at least a substantial portion, of the length of the preceramic SiC fiber116in a direction extending along the axis of rotation X-X of the platform114. In some embodiments, the e-beam radiation120emitted from the e-beam radiation mechanism112may travel in a direction that extends substantially perpendicularly through the axis of rotation X-X of the platform114. In this way, the e-beam radiation120emitted from the e-beam radiation mechanism112may extend substantially perpendicular or normal to the preceramic SiC fiber116on the platform114.

In such drum-like rotation arrangements of the preceramic SiC fiber crosslinking apparatus and methods110, the e-beam radiation mechanism112may emit e-beam radiation120and the platform114may be rotationally translated124about the axis of translation X-X to irradiate the preceramic SiC fiber116and thereby crosslink (at least partially) the preceramic SiC fiber116. In some embodiments, such rotational translation124may be provided by the translation mechanism118. The speed at which the platform114(and thereby the preceramic SiC fiber116thereon) is rotated and the strength of the dose of e-beam radiation120may be configured such that one full revolution of the platform114results in a uniform dose of e-beam radiation120to all of the preceramic SiC fiber116provided on the platform114. Further, during irradiation, coolant may be pumped or otherwise passed through the cooling channel148extending through the platform114to cool the processing surface139in contact with the wound preceramic SiC fiber116. In this way, the cooling channel148and coolant therein may be utilized to maintain or regulate the temperature of the irradiated preceramic SiC fiber116both while a particular portion of the preceramic SiC fiber116is subjected to e-beam radiation120and while that portion travels about the axis of rotation X-X and before it receives a second dose of e-beam radiation120. This cycle may be repeated such that the entirety, or at least a substantial portion, of the preceramic SiC fiber116on the platform114is crosslinked to a predetermined level via the radiation120(enough doses are applied), and preceramic SiC fiber116is prevented from reaching its softening point or melting point. After crosslinking, at least one of the flange132, window material134, translation member150and cap member152may be removed from the platform such that the drum-like platform114essentially forms an accessible spool of crosslinked preceramic SiC fiber116.

The arrangements and/or shapes of the components discussed or illustrated herein are only illustrative for the understanding of the cell structure; and are not meant to limit the scope of the invention. The exact shape, position, arrangement, orientation and the like of the components may vary.

It is to be understood that the above description is intended to be illustrative, and not restrictive. Numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the various embodiments without departing from their scope. While the dimensions and types of materials described herein are intended to define the parameters of the various embodiments, they are by no means limiting and are merely exemplary. Many other embodiments will be apparent to those of skill in the art upon reviewing the above description. The scope of the various embodiments should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects. Also, the term “operably” in conjunction with terms such as coupled, connected, joined, sealed or the like is used herein to refer to both connections resulting from separate, distinct components being directly or indirectly coupled and components being integrally formed (i.e., one-piece, integral or monolithic). Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. §112, sixth paragraph, unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure. It is to be understood that not necessarily all such objects or advantages described above may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the systems and techniques described herein may be embodied or carried out in a manner that achieves or optimizes one advantage or group of advantages as taught herein without necessarily achieving other objects or advantages as may be taught or suggested herein.