Patent Description:
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. <CIT> relates to a high purity and high strength inorganic silicon nitride continuous fiber substantially composed of Si and N and methods of producing the fiber. <CIT> relates to an apparatus and method for treating polymeric material with radiation.

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.

In one aspect, a method of crosslinking a silicon carbide fiber precursor polymer is disclosed according to claim <NUM>. 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, a system according to claim <NUM>, said system including 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. According to the invention, 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 a non-claimed 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.

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. 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 <NUM> tons per year crosslinked preceramic SiC fiber, and more preferably at least about <NUM> 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 <NUM>% performance advantage over current typical SiC fiber polymer precursors e-beam apparatus and methods. In some embodiments, testing has resulted in a <NUM>% 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 non-claimed apparatus, systems, methods and the like for crosslinking preceramic SiC fiber is illustrated in <FIG> and referenced generally by reference numeral <NUM>. As shown in <FIG>, the preceramic SiC fiber crosslinking apparatus and methods <NUM> may include several components, features and the like. The exemplary SiC fiber polymer precursor crosslinking apparatus and methods <NUM> shown in <FIG> includes an e-beam emitting mechanism <NUM>, fiber platform <NUM>, preceramic SiC fiber <NUM>, and a translation mechanism <NUM>.

The e-beam emitting mechanism <NUM> may be any mechanism effective in emitting at least one dose of e-beam radiation to the preceramic SiC fiber <NUM> provided on/in the platform <NUM>. The beam current and electron energy metrics of the doses of e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM> may be effective in at least partially crosslinking the SiC fiber polymer precursor <NUM>, 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 precursor <NUM> (e.g., softening point, melting point, etc.), the pile thickness and or arrangement of the preceramic SiC fiber <NUM> on the platform <NUM>, the relative translation speed and orientation between the preceramic SiC fiber <NUM> and the e-beam radiation <NUM>, the level or effectiveness of the temperature maintenance or cooling provided by the platform <NUM>, the number of doses of e-beam radiation applied to the preceramic SiC fiber <NUM>, and the desired level of crosslinking are some factors or variables that may affect the minimum, maximum or most effective dose of e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM> during a crosslinking process.

In some embodiments, the e-beam emitting mechanism <NUM> (in combination with other components of the apparatus <NUM>) may be configured to emit e-beam radiation at an accumulated dose between about <NUM> MGy and about <NUM> MGy, and preferably between about <NUM> MGy and about <NUM> MGy, depending upon the particular polymer of the preceramic SiC fiber <NUM>. With preceramic SiC fiber <NUM> embodiments utilizing polydisilazane as the polymer, the e-beam emitting mechanism <NUM> (in combination with other components of the apparatus <NUM>) may be configured to emit e-beam radiation <NUM> at an accumulated dose within the range of about <NUM> MGy to about <NUM> MGy. With preceramic SiC fiber <NUM> embodiments utilizing polycarbosilane as the polymer, the e-beam emitting mechanism <NUM> (in combination with other components of the apparatus <NUM>) may be configured to emit e-beam radiation <NUM> at accumulated doses greater than <NUM> MGy if the precursor to SiC fiber <NUM> is polycarbosilane, and preferably within the range of about <NUM> MGy to about <NUM> MGy.

In some embodiments, the precursor to SiC fiber <NUM> is positioned in a pile of two or more layers on the platform <NUM>. In some such embodiments, the thickness of the preceramic SiC fiber or SiC fiber polymer precursor <NUM> on the platform <NUM> is less than or equal to about <NUM> (one inch). In some such embodiments, the thickness of the preceramic SiC fiber <NUM> on/in platform <NUM> is less than or equal to about <NUM> (<NUM> inch). In some embodiments, the thickness of the preceramic SiC fiber <NUM> provided on/in the platform <NUM> is measured along the direction of the e-beam radiation <NUM> that intersects the preceramic SiC fiber <NUM>. In some embodiments, the apparatus may be configured such that the e-beam radiation <NUM> intersects the preceramic SiC fiber <NUM> in a substantial normal or perpendicular orientation.

As mentioned above, the relative speed and orientation between the preceramic SiC fiber <NUM> and the e-beam radiation <NUM> of the SiC fiber polymer precursor crosslinking apparatus <NUM> may affect, or at least be related to, the minimum, maximum or most effective dose of e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM> during a crosslinking process. As shown in <FIG>, the SiC fiber polymer precursor crosslinking apparatus and methods <NUM> may include a translation mechanism <NUM>. The translation mechanism <NUM> may be configured to translate at least one of the platform <NUM> (with the preceramic SiC fiber <NUM> contained therein/thereon) and the e-beam radiation <NUM> with respect to the other such that differing portions of the preceramic SiC fiber <NUM> receive a dose of e-beam radiation <NUM> (e.g., the entirety of the preceramic SiC fiber <NUM> on/in the platform <NUM> receives substantially the same dose of doses or e-beam radiation <NUM>). In some embodiments the translation mechanism <NUM> may be configured to translate the e-beam radiation <NUM> with respect to the platform <NUM> and the SiC fiber <NUM> carried thereon/therein. In some such embodiments, a portion or aspect of the e-beam emitting mechanism <NUM> may be translated by the translation mechanism <NUM>. In some embodiments, e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM> may be translated by the translation mechanism <NUM>. For example, the translation mechanism <NUM> may be apply an electric/magnetic field to the e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM> in order to translate the e-beam radiation <NUM> with respect to the preceramic SiC fiber <NUM>.

In some embodiments, the platform <NUM> carrying the preceramic SiC fiber <NUM> may be translated by the translation mechanism <NUM> with respect to the e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM>, as shown in <FIG>. Specifically, the crosslinking apparatus <NUM> may be configured such that, initially, the platform <NUM> carrying the preceramic SiC fiber <NUM> is translated from a first positioned where the green fiber <NUM> does not receive e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM> to a second positioned where at least a first portion 16A of the preceramic SiC fiber <NUM> receives a first dose of e-beam radiation 20A, as shown in <FIG>. Such translation may be linear, arcuate, rotational, or any other type or direction of movement that is effective in positioning the preceramic SiC fiber <NUM> in a position to receive e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM>. In some embodiments, the size, shape, orientation, layout, pattern, etc of the emitted e-beam radiation 20A may be smaller than the size, shape, orientation, layout, pattern, etc of the preceramic SiC fiber <NUM> that receives the radiation <NUM> - i.e., only a first portion 16A of the preceramic SiC fiber <NUM> at a first point in time may be exposed to e-beam radiation 20A during the crosslinking process, as shown in <FIG>. For example, the e-beam emitting mechanism <NUM> may be configured to emit e-beam radiation <NUM> in a pattern that defines a smaller area as compared to the area of the preceramic SiC fiber <NUM> on the platform <NUM> that the radiation <NUM> intersects.

During the crosslinking process, the platform <NUM> carrying the green or preceramic SiC fiber <NUM> may be translated by the translation mechanism <NUM> with respect to the e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM> to expose a second portion 16B of the preceramic SiC fiber <NUM> to a dose of e-beam radiation 20B. In this way, the translation mechanism <NUM> may be effective in exposing the entirety (or a portion) of the preceramic SiC fiber <NUM> to doses of e-beam radiation <NUM> from the e-beam emitting mechanism <NUM>. Multiple passes of the e-beam radiation <NUM> from the e-beam emitting mechanism <NUM> over the preceramic SiC fiber <NUM> thereby results in multiple doses of radiation <NUM>. As discussed further below, the temperature maintenance feature of the crosslinking apparatus and methods <NUM> allows for relatively rapid delivery of high doses of radiation <NUM>.

Translating at least one of the platform <NUM> containing the green fiber <NUM> and the e-beam radiation <NUM> with respect to the other, such that multiple portions of the preceramic SiC fiber <NUM> receive at least one dose of radiation <NUM> (i.e., the preceramic SiC fiber <NUM> is crosslinked), may be performed at a constant speed or at a variable speed. For example, the arrangement or orientation of the preceramic SiC fiber <NUM> on the platform <NUM> (e.g., constant pile thickness) may dictate that a constant translation speed between the preceramic SiC fiber <NUM> and the e-beam radiation <NUM> via the translation mechanism <NUM> would result in substantially uniform doses of radiation throughout the preceramic SiC fiber <NUM>. However, other arrangements or orientations of the preceramic SiC fiber <NUM> on the platform <NUM> may dictate that a variable translation speed between the preceramic SiC fiber <NUM> and the e-beam radiation <NUM> via the translation mechanism <NUM> would result in substantially uniform doses of radiation throughout the preceramic SiC fiber <NUM>. In still other variations, non-uniform doses of radiation to the preceramic SiC fiber <NUM> may be desirable and achieved, at least in part, by the speed or path of the relative translation between the preceramic SiC fiber <NUM> and the e-beam radiation <NUM> via the translation mechanism <NUM>. In some embodiments, the translation mechanism <NUM> is configured to translate at least one of the platform <NUM> containing the preceramic SiC fiber <NUM> and the e-beam radiation <NUM> with respect to the other such that the translation speed between the preceramic SiC fiber <NUM> and the e-beam radiation <NUM> is substantially constant and relatively great. In some embodiments, the translation speed between the preceramic SiC fiber <NUM> and the e-beam radiation <NUM> may be at least about <NUM>/min. In some embodiments, the translation speed between the preceramic SiC fiber <NUM> and the e-beam radiation <NUM> may be at least about <NUM>/min.

The translation of the preceramic SiC fiber <NUM> (via the platform <NUM>) by the translation mechanism <NUM> during the crosslinking process may be linear, arcuate, rotational or any other type or direction of movement that is effective in positioning the preceramic SiC fiber <NUM> (via the platform <NUM>) in a position such a second portion 16B of the preceramic SiC fiber <NUM> is irradiated, as indicated by the exemplary directional arrows emanating about the portion of the platform <NUM> shown in <FIG>. In the embodiment shown in <FIG>, the preceramic SiC fiber <NUM> is positioned on a substantially planar surface of the platform <NUM>. In such a non-claimed embodiment, as shown in <FIG>, the translation mechanism <NUM> may be configured to translate the platform <NUM>, and thereby the preceramic SiC fiber <NUM> thereon, along a substantially linearly plane or direction <NUM>. By translating the platform <NUM>, and thereby the preceramic SiC fiber <NUM> thereon, back and forth along the substantially linearly plane or direction <NUM>, the translation mechanism <NUM> can be effective in irradiating the entirety of the preceramic SiC fiber <NUM> with several doses of the e-beam radiation <NUM>.

Another example of potential green or preceramic SiC fiber <NUM> layout on the platform <NUM> and the relative translation between the e-beam radiation <NUM> emitted from the e-beam emitting mechanism <NUM> and the platform <NUM> (and thereby the preceramic SiC fiber <NUM> thereon), is shown in <FIG>. As shown in <FIG>, in some embodiments the preceramic SiC fiber <NUM> may be positioned on a surface of the platform <NUM> in an arcuate, circular or spiral arrangement in one or more layers about an axis X-X that passes through the platform <NUM>. Similarly, in some embodiments the translation mechanism <NUM> may be configured to translate the platform <NUM>, and thereby the preceramic SiC fiber <NUM> thereon, in a rotational direction <NUM> about the X-X. Rotational movement <NUM> of the platform <NUM>, and thereby the preceramic SiC fiber <NUM> thereon, via the translation mechanism <NUM> can be effective in irradiating the entirety of the preceramic SiC fiber <NUM> with several doses of the e-beam radiation <NUM> (one dose per revolution). In some such embodiments, the central area of the platform <NUM> about the axis of rotation X-X may not include preceramic SiC fiber <NUM> thereon as such preceramic SiC fiber <NUM> would receive substantially higher doses of radiation <NUM> than portions distal the axis of rotation X-X. In some such embodiments, the crosslinking apparatus and methods <NUM> may be configured such that the axis of rotation X-X of the platform <NUM>, and thereby the preceramic SiC fiber <NUM>, may be substantially parallel with the direction of the e-beam radiation <NUM>.

An exemplary non-claimed construction or arrangement of the green or preceramic SiC fiber platform <NUM> is shown in <FIG>, <FIG>. As shown in <FIG>, the platform <NUM> may form or include a chamber <NUM> for containing the green SiC fiber <NUM> being processed (i.e., irradiated and thereby crosslinked). The chamber <NUM> may be substantially sealable or sealed such that the passage or migration of moisture and oxygen into the chamber <NUM>, and thereby onto or about the preceramic SiC fiber <NUM> contained therein, is substantially prevented during processing. In some embodiments, the chamber <NUM> may be configured such that moisture and oxygen contained therein is less than or equal to about <NUM> ppm during processing to avoid significant reaction with the radicals. In some embodiments, the chamber <NUM> may be configured such that oxygen contained therein is less than or equal to about <NUM> ppm during processing. In some embodiments the chamber <NUM> is substantially hermetically sealable or sealed.

The chamber <NUM> may be formed, at least in part, by a flange <NUM>, window member <NUM>, seal member <NUM> and base <NUM>, as shown in <FIG>. The flange <NUM> may form an opening through which the e-beam radiation <NUM> may be projected and, ultimately, absorbed by the preceramic SiC fiber <NUM>. The flange <NUM> may also be utilized, at least in part, to couple a window member <NUM> over the opening. The window member <NUM> may be any material or arrangement that is penetrable by e-beam radiation <NUM> at levels that are effective in crosslinking the preceramic SiC fiber <NUM> contained within the chamber <NUM>. The window member <NUM> may 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 fiber <NUM> during crosslinking. In some embodiments, the window member <NUM> is titanium foil. In some such embodiments, the titanium foil is about <NUM> (2mil) thick.

In some embodiments, as shown in <FIG>, the preceramic SiC fiber platform <NUM> may include at least one seal member <NUM> to ensure moisture and oxygen is substantially prevented from penetrating or migrating into the chamber <NUM> during processing (i.e., crosslinking). For example, at least one seal member <NUM> may be utilized to seal, at least in part, the window member <NUM> to the flange <NUM> and/or a base <NUM>. The base <NUM> may include a recessed treatment surface <NUM> (or other feature) configured to provide a space between the base <NUM> and the window member <NUM> when the flange <NUM> and window member <NUM> are coupled to the base <NUM>, as shown in <FIG>. In this way, the treatment surface <NUM> may be configured to receive the preceramic SiC fiber <NUM> thereon. As also shown in <FIG>, at least the flange <NUM> and base <NUM> may include corresponding apertures 40A and 40B, respectively, which facilitate coupling of the flange <NUM>, window member <NUM>, seal member <NUM> and base <NUM> to form the chamber <NUM> via fasteners (not shown). Further, the base <NUM> may include one or more port <NUM> configured for the removal of moisture and oxygen of the chamber <NUM> once the chamber <NUM> is sealed. For example, the at least one port <NUM> may be utilized to evacuate any moisture and oxygen from the chamber <NUM> after sealing, and/or to introduce an environment into the chamber <NUM> that facilities, or at least does not interfere with, crosslinking of the preceramic SiC fiber <NUM>. For example, the at least one port <NUM> may be utilized to evacuate moisture and oxygen from the chamber <NUM> such that the chamber <NUM> contains less than or equal to about <NUM> ppm moisture and oxygen, and preferably less than or equal to about <NUM> ppm of oxygen, during processing (e.g., irradiation). Once moisture and oxygen are substantially removed from the chamber <NUM> (and/or an environment is put into the chamber <NUM>), the at least one port <NUM> may be substantially sealed (e.g., hermetically sealed) to thereby seal the substantially oxygen and moisture free chamber <NUM>.

As shown in <FIG>, the base <NUM> may include a coolant inlet <NUM>, a coolant outlet <NUM> and a coolant channel <NUM> extending therebetween. The coolant inlet <NUM>, coolant outlet <NUM> and a coolant channel <NUM> may allow heat transfer material or coolant (not shown) to flow through the base <NUM>. In the exemplary embodiment shown in <FIG>, the base <NUM> is of two-part construction including a first bottom portion <NUM> and a second top portion <NUM>. The exemplary second top portion <NUM> includes or forms the treatment surface <NUM> one side, and includes or forms a portion of the coolant inlet <NUM>, coolant outlet <NUM> and a coolant channel <NUM> on an opposing side, as shown in <FIG>. In such an arrangement, heat transfer material or coolant flowing through the coolant channel <NUM> can absorb heat conducting through the second top portion <NUM> (and potentially the first bottom portion <NUM>) from the treatment surface <NUM> and, ultimately, from the irradiated preceramic SiC fiber <NUM> to maintain the temperature thereof during crosslinking. When assembled, as shown in <FIG>, the first bottom portion <NUM> and the second top portion <NUM> may form a seal <NUM> therebetween such that a sealed coolant channel is formed through the base <NUM> (except for the inlet <NUM> and outlet <NUM>). 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 platform <NUM> to force the flow of the heat transfer material or coolant through the coolant channel <NUM> of the platform <NUM> from the coolant inlet <NUM> to the coolant outlet <NUM>. In this way, the platform <NUM> (or apparatus or methods <NUM>) includes an integrated heat exchanger that maintains or regulates the temperature of the preceramic SiC fiber <NUM> on the platform concurrently with the doses of e-beam radiation <NUM> during the crosslinking process (i.e., both during doses of radiation and after each dose of radiation).

The coolant channel <NUM>, and coolant flowing therein during crosslinking, allows for relatively high dose rates of the e-beam radiation <NUM> to be applied without melting the preceramic SiC fiber <NUM>. In some embodiments, the coolant channel <NUM>, and coolant flowing therein, may be configured to maintain or regulate the temperature of the preceramic SiC fiber <NUM> below the softening point of the preceramic SiC fiber <NUM> during relatively high dose rates of e-beam radiation <NUM> (e.g., greater than or equal to about <NUM> kGy/sec) by maintaining or cooling the temperature of a portion of the platform <NUM> (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 channel <NUM> may be below the softening point of the preceramic SiC fiber <NUM> provided on the platform <NUM>. In some embodiments, the coolant channel <NUM>, and coolant flowing therein, may be configured to maintain or regulate the temperature of the preceramic SiC fiber <NUM> below the melting point of the preceramic polymer during relatively high dose rates of e-beam radiation <NUM> (e.g., greater than or equal to about <NUM> kGy/sec) by maintaining or cooling the temperature of a portion of the platform <NUM> (e.g., via conduction, convection, or a combination thereof). In some embodiments, the temperature of coolant flowing through the coolant channel <NUM> is at least about <NUM> below the softening point of the preceramic SiC fiber <NUM> within the chamber <NUM> of the platform <NUM>. In some embodiments, the platform <NUM> includes polysilazane SiC fiber <NUM>, and the coolant flowing through the coolant channel <NUM> is configured (e.g., temperature, flow rate, etc.) to maintain or prevent the temperature of the polysilazane SiC fiber <NUM> from exceeding about <NUM>. In some embodiments, the platform <NUM> includes polycarbosilane SiC fiber <NUM>, and the coolant flowing through the coolant channel <NUM> is configured (e.g., temperature, flow rate, etc.) to maintain or prevent the temperature of the polycarbosilane SiC fiber <NUM> from exceeding about <NUM>.

Another exemplary apparatus, systems, methods and the like for crosslinking preceramic SiC fiber is illustrated in <FIG> and referenced generally by reference numeral <NUM>. As shown in <FIG>, the preceramic SiC fiber crosslinking apparatus and methods <NUM> may include several components, features and the like that function similar to the exemplary preceramic SiC fiber crosslinking apparatus, system, method and the like <NUM> described above with reference to <FIG> and therefore like reference numerals preceded by the numeral "<NUM>" 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 like <NUM> (and any alternative embodiments thereof). As shown in <FIG>, inter alia, the exemplary preceramic SiC fiber crosslinking apparatus, systems, methods and the like <NUM> of <FIG> differs from the embodiments <NUM> of <FIG> with respect to the configuration or arrangement of the preceramic SiC fiber platform <NUM>, the preceramic SiC fiber <NUM> provided on the platform <NUM>, and the translation of the preceramic SiC fiber platform <NUM> (and thereby the preceramic SiC fiber <NUM> provided thereon) and/or the e-beam radiation <NUM> during the crosslinking process.

As shown in <FIG>, the preceramic SiC fiber crosslinking apparatus and methods <NUM> are configured to crosslink (i.e., irradiate) the preceramic SiC fiber <NUM> provided on the platform <NUM> via rotation <NUM> of the platform <NUM> about an axis of rotation X-X by the translation mechanism <NUM>.

The processing surface <NUM> of the base <NUM> of the platform <NUM> carrying the preceramic SiC fiber <NUM> thereon is formed about, and potentially defines, the axis of rotation X-X. For example, the base <NUM> forms or includes a drum, spool, cylinder or like shape such that the processing surface <NUM> is arcuate and extends, at least partially, about the axis of rotation X-X, as shown in <FIG> and <FIG>. In some embodiments, the base <NUM> (and/or the processing surface <NUM> thereof) forms an axis, and such axis may be substantially aligned with the axis of rotation X-X of the processing surface <NUM>. In some embodiments, the processing surface <NUM> of the base <NUM> of the platform forms a cylindrical shape with a diameter within the range of about <NUM> (<NUM> inches) to about <NUM> (<NUM> feet), and preferably within the range of about <NUM> (<NUM> inches) to about <NUM> (<NUM> feet). As shown in <FIG> and <FIG>, in some embodiments the flange <NUM> and window member <NUM> may form a drum, spool, cylinder or like shape such that the flange <NUM> couples, at least in part, the window member <NUM> about the arcuate processing surface <NUM> of the base <NUM>. In this way, the flange <NUM> and window member <NUM> may seal, at least partially, the preceramic SiC fiber <NUM> to the base <NUM>.

The platform <NUM> may include an inner area that includes a cooling channel <NUM> for the flow of heat transfer material or coolant therethrough, as shown in <FIG>. In some embodiments, the cooling channel <NUM> may 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 channel <NUM> may be configured to maintain, regulate or cool the processing surface <NUM> of the base <NUM> of the platform <NUM>, and thereby the preceramic SiC fiber <NUM> provided on the processing surface <NUM>. In some embodiments, the processing surface <NUM> of the base <NUM> of the platform <NUM> may be formed on an outer surface of a wall of the base <NUM>, and the cooling channel <NUM> may be provided on an inner surface of the wall of the base <NUM> opposing the outer surface. In this way, heat may travel via conduction (and/or another heat transfer mechanism) from the processing surface <NUM> and through the wall of the base <NUM> to the inner surface and, eventually, to the coolant flowing through the cooling channel <NUM>.

In some embodiments, as shown in <FIG>, a cap member <NUM> may be coupled to the base <NUM>. The cap member <NUM> may enclose an inner portion of the base <NUM>, such as an inner portion including the cooling channel <NUM>. The cap member <NUM> may provide for the sealing of the flange <NUM> and window member <NUM> over the preceramic SiC fiber <NUM> to create a sealed chamber or cavity for the preceramic SiC fiber <NUM>. As noted above, the preceramic SiC fiber chamber, enclosure or cavity of the platform <NUM> for containing the preceramic SiC fiber <NUM> may 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 in <FIG>, a translation member <NUM> may be associated with the cap member <NUM> and the base <NUM>. The at least one translation member <NUM> may be configured to be utilized by the translation mechanism <NUM> to translate (e.g., rotate) the platform <NUM> (and thereby the preceramic SiC fiber <NUM> thereon) about the axis of rotation X-X.

As shown in <FIG>, the processing surface <NUM> of the drum-like base <NUM> of the platform <NUM> is wound with preceramic SiC fiber <NUM>. In some embodiments, the preceramic SiC fiber <NUM> on the platform <NUM> may be wound directly from a spinneret of a fiber spinning line. The preceramic SiC fiber <NUM> may be wound to form a pile of multiple layers of preceramic SiC fiber <NUM>. In some such embodiments, the thickness of the preceramic SiC fiber <NUM> of platform <NUM> may be less than or equal to about <NUM> (one inch). In some embodiments, the thickness of the preceramic SiC fiber <NUM> of platform <NUM> may be about <NUM> (<NUM> inch).

Once the platform <NUM> is wound with preceramic SiC fiber <NUM>, the cap member <NUM> and/or translation member <NUM> may be coupled to the base <NUM> of the platform <NUM>, as shown in <FIG>. Once the cap member <NUM> is coupled to the platform <NUM> wound with SiC fiber <NUM>, the flange <NUM> and window member <NUM> may be coupled to the platform <NUM> to form a substantially sealed area, cavity, enclosure or chamber about the preceramic SiC fiber <NUM>. As noted above, the sealed area, cavity, enclosure or chamber about the preceramic SiC fiber <NUM> may 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 fiber <NUM> that facilities crosslinking of the preceramic SiC fiber <NUM> via e-beam radiation <NUM>. As shown in <FIG>, the sealed platform <NUM> may be translated in a direction <NUM> such that e-beam radiation <NUM> emitted from the e-beam radiation mechanism <NUM> passes through the window member <NUM> and intersects the preceramic SiC fiber <NUM>. In some embodiments, such translation of the platform <NUM> may be provided by the translation mechanism <NUM>. As also shown in <FIG>, in some embodiments the e-beam radiation mechanism <NUM> and the platform <NUM> may be arranged or oriented such that e-beam radiation <NUM> extends over the entirety, or at least a substantial portion, of the length of the preceramic SiC fiber <NUM> in a direction extending along the axis of rotation X-X of the platform <NUM>. In some embodiments, the e-beam radiation <NUM> emitted from the e-beam radiation mechanism <NUM> may travel in a direction that extends substantially perpendicularly through the axis of rotation X-X of the platform <NUM>. In this way, the e-beam radiation <NUM> emitted from the e-beam radiation mechanism <NUM> may extend substantially perpendicular or normal to the preceramic SiC fiber <NUM> on the platform <NUM>.

In such drum-like rotation arrangements of the preceramic SiC fiber crosslinking apparatus and methods <NUM>, the e-beam radiation mechanism <NUM> emits e-beam radiation <NUM> and the platform <NUM> is rotationally translated <NUM> about the axis of translation X-X to irradiate the preceramic SiC fiber <NUM> and thereby crosslink (at least partially) the preceramic SiC fiber <NUM>. In some embodiments, such rotational translation <NUM> may be provided by the translation mechanism <NUM>. The speed at which the platform <NUM> (and thereby the preceramic SiC fiber <NUM> thereon) is rotated and the strength of the dose of e-beam radiation <NUM> may be configured such that one full revolution of the platform <NUM> results in a uniform dose of e-beam radiation <NUM> to all of the preceramic SiC fiber <NUM> provided on the platform <NUM>. Further, during irradiation, coolant may be pumped or otherwise passed through the cooling channel <NUM> extending through the platform <NUM> to cool the processing surface <NUM> in contact with the wound preceramic SiC fiber <NUM>. In this way, the cooling channel <NUM> and coolant therein may be utilized to maintain or regulate the temperature of the irradiated preceramic SiC fiber <NUM> both while a particular portion of the preceramic SiC fiber <NUM> is subjected to e-beam radiation <NUM> and while that portion travels about the axis of rotation X-X and before it receives a second dose of e-beam radiation <NUM>. This cycle may be repeated such that the entirety, or at least a substantial portion, of the preceramic SiC fiber <NUM> on the platform <NUM> is crosslinked to a predetermined level via the radiation <NUM> (enough doses are applied), and preceramic SiC fiber <NUM> is prevented from reaching its softening point or melting point. After crosslinking, at least one of the flange <NUM>, window material <NUM>, translation member <NUM> and cap member <NUM> may be removed from the platform such that the drum-like platform <NUM> essentially forms an accessible spool of crosslinked preceramic SiC fiber <NUM>.

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 scope of the invention as defined by the following claims. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. 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). 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.

While the invention has been described in detail in connection with only a limited number of embodiments, it should be readily understood that the invention is not limited to such disclosed embodiments. Rather, the invention can be modified to incorporate any number of variations, alterations, substitutions or equivalent arrangements not heretofore described, but which are commensurate with the scope of the invention. Additionally, while various embodiments of the invention have been described, it is to be understood that aspects of the disclosure may include only some of the described embodiments. Accordingly, the invention is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.

Claim 1:
A method of crosslinking a silicon carbide fiber precursor polymer (<NUM>), comprising:
exposing a first portion (16A) of silicon carbide fiber precursor polymer provided on a platform (<NUM>) to e-beam radiation (<NUM>) from an e-beam radiation mechanism (<NUM>), wherein the platform (<NUM>) comprises a drum-like base (<NUM>) including a processing surface (<NUM>) which carry the silicon carbide fiber precursor polymer (<NUM>);
translating at least one of the platform (<NUM>) and the e-beam radiation (<NUM>) with respect to the other and exposing a second portion (16B) of the silicon carbide fiber precursor polymer to e-beam radiation, wherein translating at least one of the platform and the e-beam radiation (<NUM>) with respect to the other includes rotating the platform about an axis of rotation; and
regulating the temperature of the platform (<NUM>) to thereby prevent the temperature of the first and second portions (16A,B) of the silicon carbide fiber precursor polymer (<NUM>) from reaching their softening point due to the e-beam radiation; and characterized in that
the drum-like base (<NUM>) forms a drum-like surface such that the processing surface (<NUM>) is arcuate and extends, at least partially, about the axis of rotation, wherein the silicon carbide fiber precursor polymer (<NUM>) is provided on the processing surface (<NUM>) of the drum-like base (<NUM>) of the platform (<NUM>) by winding the silicon carbide fiber precursor polymer on the platform.