Heat treatment optimization of anthracene and its effect as carbon precursor in carbon fiber/carbon composite development

Abstract

Field of carbon/carbon composite materials still offers opportunities for exploration and invention of new production processes or particular compounds as carbon sources from which worth final product may be derived or else another branch of utilization introduced. In former research work anthracene substance was determined to be one of such potential sources of carbon. Therefore, dissertation thesis is focused on the anthracene utilization as matrix carbon precursor; production process and performance of anthracene at individual production stages in carbon fiber/carbon composite development. Technical anthracene with purity of 94.41 weight % was used. For purpose of heat treatment optimization, heating patterns were designed to distinguish the influence of temperature and production time on resulting products. Final temperatures 200 °C, 250 °C, 300 °C, 350 °C, 400 °C and 450 °C, respectively, were established with rate of heating as 1 K per minute up to 100 °C for all tests and continuously by 1 K•min-1, 0.066 K•min-1 or 0.033 K•min-1 up to the selected particular final temperatures. As the optimum heat treatment, final temperature of 250 °C at rate of 0.033 K•min-1 was determined with production time duration about 76 hours and 20 minutes. For fiber preforms impregnation by anthracene various methods were tested, e. g. usage of non-treated anthracene, toluene as solvent or anthracene melting. The most effective technique of infiltration was application of anthracene in liquid state with no presence of additional solvent. Influence of catalysts on anthracene polycondensation was studied by means of model agents such as aluminium chloride, zinc chloride, ferric chloride and chromium trichloride. Thermogravimetric analysis and Fourier – transform infrared spectroscopy from qualitative point of view were used for samples evaluation. The biggest effect on anthracene polycondensation was revealed by ferric chloride while low impact was noticed by zinc chloride and chromium trichloride. As a subsequent step in carbon fiber/carbon material processing carbonization up to 500 °C by rate of 0.033 K•min-1 was performed with anthracene sample without presence of catalyst as well as with presence of ferric chloride (10 wt. %). Influence of catalyst resulted in connection of fibers into bundles by carbonisate. In general, achieved findings and observation are very positive, nevertheless still further research and detailed investigation is needed.