Effects of coal characteristics on the structure and performance of coal-based carbon foam prepared by self-foaming technique under atmospheric pressure

Carbon foams with open cell structure and high compressive strength were produced using three strongly caking bituminous coals without any pretreatment, by a proposed self-foaming technique under atmospheric pressure with the characteristics of simple operation, safety, and efficiency. The chemical composition, thermoplastic behavior, and pyrolysis characteristics of the raw coals were characterized by FT-IR, Raman, solid-state 13C NMR, Gieseler fluidity, Audibert-Arnu dilatation, and TG/DTG techniques. The results showed that the structure and mechanical properties of the carbon foams could be mainly controlled by fluidity and the chemical composition of the raw coals under the same initial foaming pressure. The carbon foams produced from DS coal with high fluidity and aliphatic carbon contents originated from the cyclic aliphatic structures presented open-cell structures, large cell size, and high porosity (78.43%) and showed a low compressive strength of 2.71 MPa. Carbon foam obtained from the TL coal with low fluidity, and large aromatic cluster structure presented thick ligaments, relatively uniform cell distribution and better crystalline structure, which showed the highest compressive strength of 18.13 MPa.