超临界发泡制备泡沫炭及其泡孔形成机理

Preparation and Foaming Mechanism of Carbon Foams by Supercritical Foaming Method

分别以中间相沥青和甲苯作碳质前驱体和发泡剂,采用超临界发泡技术制备出孔径为10~25μm的泡沫炭,并着重研究了超临界发泡条件对泡沫炭的孔形及韧带结构的影响。超临界发泡包括成核、扩散、聚集及膨胀过程,同时泡孔的形成也是热力学、动力学及力学行为综合作用的结果。由于中间相沥青中存在轻组分,超临界发泡过程伴随着自发泡过程,由此可获得层次孔结构的泡沫炭。

Carbon foams with pore sizes of 10~25μm were prepared by supercritical foaming method.Mesophase pitch and toluene were introduced as the carbonaceous precursor and supercritical agent,respectively.The effects of supercritical foaming conditions on the pore shape and ligament structure were investigated.The supercritical foaming process,including nucleation,diffusion,aggregation and expanding process,was the result of the exchange of mass and energy as well as the kinetic and mechanical behaviors between supercritical toluene and pitch matrix.Hierarchical porous carbon foams arose from the supercritical foaming process combined with self-bubble process are attributed to the light components of mesophase pitch.