The internal friction of unidirectional CC composites fabricated in a magnetic field Original Research Article

Previous studies have shown that lamellae of mesophase pitch prefer to be oriented parallel to a magnetic field. In the present work the matrix mesophase layers of the C/C composites were oriented perpendicular to the carbon fibers by a 8000 G magnetic field. This study is concerned with the internal friction of unidirectional C/C composites produced by the method of the present research. It is found that the internal friction of unidirectional C/C composites fabricated with mesophase pitch precursor in a 8000 G magnetic field is larger than that of the composites in the absence of a magnetic field; the higher the degree of graphitization of the composites, the larger the internal friction of the composites; and the higher the density of the composites, the larger the internal friction of the composites. The internal friction of the C/C composites decrease with the oscillation frequency from 0.01 to 1 Hz, and then slightly increases up to 5 Hz.