DYNAMIC-MECHANICAL PROPERTIES OF CARBON-CARBON COMPOSITES

The dynamic mechanical analysis (DMA) method was utilized to investigate the dynamic mechanical properties of the carbon-phenolic composite, and of carbon-carbon (C/C) composites carbonized at 1000 degrees C, and graphitized at 2200 degrees C. The measurements were performed in the temperature range 50-450 degrees C. Results show that the carbon-phenolic composite has the highest storage modulus, while the carbonized C/C composites possess higher storage modulus than the graphitized C/C composite. The storage moduli of carbonized and graphitized C/C composite do not change significantly in the test temperature range. The tan delta, loss factor, of carbonized C/C composites increases 59.5% during the tests from 50 to 450 degrees C, and that of the graphitized C/C decreases 9.74% in the same temperature range; graphitized C/C shows the highest tan delta at 50 degrees C. The carbon-phenolic composite shows a damping peak at 250 degrees C, which is probably due to the transition from glassy state to rubbery state of the phenolic matrix. The higher tan delta of the graphitized C/C composite may be due to matrix graphitization, fibre-matrix debonding and crack formation, which were observed on the micrographs.