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Fabrication of coal tar pitch–derived reticulated carbon foam as oxidation-resistant thermal insulation

Yu, Ming, Li, Cuiqin, Ao, Xianquan, Chen, Qianlin
Journal of analytical and applied pyrolysis 2019 v.141 pp. 104643
air, bubbles, carbon, chemical composition, coal tar, foaming, foams, insulating materials, oxidation, pyrolysis, temperature, viscosity
This report proposes a new method for fabricating tailored coal tar pitch (CTP) precursors to enhance the oxidation-resistant thermal insulation performance of the final carbon foam. A gradient separation method is used to produce controllable CTP using low-temperature coal tar at temperatures between 340 °C and 460 °C. The effects on the chemical composition, pyrolysis, and rheological behaviour of CTP through the treatment temperature and removal of low-molecular weight species by gradient separation and its distillate were analysed. The results revealed that the chemical compositions of suitable CTPs can be tailored using the gradient selectivity separation method, which decreases the viscosity of CTP and facilitates the growth of bubbles for the preparation of carbon foams during the foaming process. The performance of the carbon foam depends on the pore structure. Carbon foams with pentagonal dodecahedron pore structures showed excellent thermal insulation performance (0.028–0.053 W∙m−1∙K−1). The carbon foams also exhibited good oxidation resistance at 1000 ℃ in air, as there is no transitional pore system for oxidizing gas diffusion in the pentagonal dodecahedron structure, and the oxidation reaction occurs on the surface of the carbon foam.