Influence of Adding MCMB into Carbon-Carbon Composites on their Microstructures, Thermal and Electrical Properties during Pyrolysis

• Main Authors: Hsien-Lin Hu, 胡憲霖
• Other Authors: Tse-Hao Ko
• Format: Others
• Language: en_US
• Published: 2006
• Online Access: http://ndltd.ncl.edu.tw/handle/04574110593216054018

博士 === 逢甲大學 === 材料科學所 === 94 === The work tests the effect on microstructure, flexural strength, flexural moduli, plus the electrical and thermal conductivity of phenolic resin and carbon/carbon composites with Mesocarbon Microbeads (MCMBs) content ranging 0-30% by weight during carbonization and graphitization . These C/C composites were reinforced by oxidative PAN -base fiber felts and PAN-based carbon fiber felts, and matrix precursor was resol-type-phenolic resin. MCMBs with a weight fraction of 0-30% were added to the matrix, to elucidate effect. MCMB is a graphitizable carbon material and Phenolic resin is an non-graphitizable. The thermal and electrical conductivity of carbon material depend on degree of arrangement of carbon basal plane. Thus, we try to find a low-cost route to fabricate carbon-carbon composites owning high thermal and electrical conductivity. After heat treated at 2500℃, the flexural strength and modulus the phenoplic resin with added 30 wt.% MCMBs improve 36.2% and 90.3%, comparing with that of the zero wt.% MCMB added. The phenolic resin with 30 wt.% MCMBs heat-treated at 2500℃ also showed that electric resistance reduced from 3.82×10-2 to 2.45×1 0-2 Ωcm and thermal conductivity improved from 5.8 to 8.0 W/mk. The carbon/carbon composites were prepared from oxidative PAN fiber felts, resol- type phenolic resin and MCMBs derived from coal tar. Results showed carbon/carbon composite with addition of 10 ~30 wt.% MCMB having higher density, greater size (LC), and higher preferred orientation than for carbon/carbon composites without MCMB during heat-treatment. These composites also exhibited an improvement in flexural strength from 19.7% to 30.3%. Flexural moduli of these composites added with MCMB is increased by 15.1% to 31.3% as compared to that of the zero wt.% MCMB added composites. These composites also showed improved electric conductivity from15.1% to 43.7% and thermal conductivity from 12 % to 31.3%. On other hand, the carbon- carbon composites were prepared from PAN-based carbon fiber felts, resol-type phenolic resin and Mesocarbon Microbeads (MCMBs), which derived from coal tar. The results showed that the carbon/carbon composite with addition of 10 ~30 wt% MCMBs has a higher density and preferred orientation than those of carbon/ carbon composite without MCMBs during heat-treatment. These composites also exhibited an improvement in flexural strength from 21.4% to 34.0%. These composites also showed an improvement in electric conductivity from 25.0% to 59.6% and that in thermal conductivity from10.5 % to 18.0%.