Features & Characteristics of Carbon Nano Fiber

• Pyrograf®-I is a substrate grown fiber which attains lengths of up to 10 cm.  Pyrograf-I has a larger diameter than Pyrograf-III and performs high thermal conductivity.  It is useful in carbon pre-form or metal matrix composites for thermal management applications.

• Pyrograf®-III is grown completely in the gas phase, and tends to be grown in an entangled mass. It is now grown without any detectable pyrolytic overcoat. Pyrograf®-III may be properly referred to as a nanofiber. Pyrograf®-III is highly ordered without heat treatment (although heat treatment is still useful as a means of removing impurities, if desired).
   
• Pyrograf®-IV is similar to Pyrograf®-III, but contains an additional pyrolytic overcoat so that it attains a diameter of a few microns. Therefore, it is not properly referred to as a "nanofiber" but actually becomes a "microfiber." Because of its larger diameter, Pyrograf®-IV can be considered as an additive for high thermal conductivity.

    The properties of the three Pyrograf® types are summarized below (incidentally, ASI does not offer a material called Pyrograf®-II. It was abandoned in favor of Pyrograf®-III by the mid 1990s). It is not practical to measure single-fiber properties for very tiny fibers, but the strength, modulus, and CTE are inferred to be similar for all three materials (as measured for the case of Pyrograf®-I).