Fiber Architectures

Fiber architecture is similar to that used for polymer matrix composites. Either unidirectional or woven cloth can be prepregged, or textile techniques, such as weaving or braiding, can be used to form a near net preform.11

To form unidirectional prepreg, tows are precoated with the interfacial protection system and filament wound on a drum, which can be prepregged with the ceramic matrix precursor material or held together with a fugitive binder. The sheets are then cut from the drum and layed-up in the desired orientation. For fabric constructions, the tows are usually woven prior to applying the interfacial coatings to minimize damage to the coatings. These prepregging approaches are illustrated in Fig. 10.5.

Near net shaped preforms can also be constructed using textile technologies, such as weaving, stitching, and braiding. Again, to avoid coating damage, the interfacial coating system is normally applied after the textile forming operations are complete, as shown in Fig. 10.6.

Fiber Tows

CVD Fiber Coating

Lay-up Unidirectional Material

Impregnate with Matrix Precursor

Lay-up 2-Dimensional Laminate

Fiber Tows

Weave 2-Dimensional Laminate

CVD Fiber Coating

Impregnate with Matrix Precursor

Lay-up 2-Dimensional Laminate

Fig. 10.5. Ceramic Prepreg Fabrication or

Fiber Tows

Weave or Braid 2-D or 3-D Part

CVD Fiber Coating or

Fig. 10.6. Ceramic Preform Fabrication

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