Overview Of:
Carbon Fiber
Carbon fiber — by far the most widely used fiber in high-performance
applications — is produced from a variety of precursors, including
polyacrylonitrile (PAN), rayon and pitch. The precursor fibers are heated and
stretched to create the high-strength fibers. The first high-performance carbon
fibers on the market were made from rayon precursor. PAN- and pitch-based fiber
have replaced rayon-based fiber in most applications, but the latter’s “dogbone”
cross-section often makes it the fiber of choice for carbon/carbon (C/C)
composites. PAN-based carbon fibers are the most versatile and widely used. They
offer an amazing range of properties, including excellent strength — to 1,000
ksi — and high stiffness. Pitch fibers, made from petroleum or coal tar pitches,
have high to extremely high stiffness and low to negative axial CTE. Their CTE
properties are especially useful in spacecraft applications that require thermal
management, such as electronic instrumentation housings. Although they are
stronger than glass or aramid fibers, carbon fibers are not only less
impact-resistant but also can experience galvanic corrosion in contact with
metal. Fabricators overcome the latter problem by using a barrier material or
veil ply — often fiberglass/epoxy — during laminate
layup.
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