MICROSTRUCTURE OF PITCH-BASED CARBON FIBERS
沥青基碳纤维的显微结构

Isotropic pitch-based carbon fibers have a structural heterogeneity.Two phasewere distinguished,viz.crystalline graphite phase and amorphous carbon phase.Crystallinegraphite phase is made of sheet-like,randomly preferred crystallites which loosely entangle andform network structure.The amorphous carbon phase which consists of poorly developedcrystallites,single carbon layers and amorphous carbon is inlayed among the crystallites.Thepacking size and order of crystallites are enhanced with the increase of heat treatment tempera-ture.The crystallites are severely distorted.The degree of distortion depends on the size andstacking of carbon layers.There are two types of fault stacking of carbon layers.One is thatfault stackings of carbon layers take place at one place,which forms the sub-grain boundaries.The other is that fault stackings of carbon layers distribute randomly in the different parts of thecrystallite,which leads to a decreasing of order of the crystallite.