Preparation and characterization of coal-based carbon foams by microwave heating process under ambient pressure

To reduce significantly the preparation time and cost in energy of coal-based carbon foams and to develop facile synthesis condition, a microwave heading process (MHP) for fabricating coal-based carbon foams was suggested. The preparation time, the structure and the compressive strength of carbon foams fabricated respectively by MHP and carbonization in nitrogen atmosphere at high pressure (CNHP) were contrastively studied. The results show that MHP exhibited three distinct characteristics in contrast to CNHP. First, the preparation time of green foam is shortened by 55.2% based on the microwave heating principle. Secondly, the preparation conditions are more moderate, only under ordinary pressure instead of high pressure. Thirdly, the resultant carbon foams display small pore diameter with narrow pore size distribution and high compressive strength. More importantly, the strategy of coal-based carbon foam by microwave heating process can be applied to other thermoplastic precursor foaming to obtain macro-porous materials.