Microstructure and mechanical behaviors of T700 carbon fiber reinforced C/SiC composites via precursor infiltration and pyrolysis

Abstract

A new tow-spreading technology was employed to spread T700SC 12K fibers to a width of 12mm, based on which plain weave carbon cloth with a low areal density of 100g/m2 and the thickness of 0.1mm was obtained. 2D C/SiC composites reinforced by such T700 carbon cloth, together with T300 3K plain weave carbon cloth (200g/m2 areal density) for comparison, were prepared by precursor infiltration and pyrolysis process. Chemical vapor deposition pyrocarbon (PyC) interphase was also used to modify the surface structures of both fiber reinforcements. The mechanical behaviors of the composites were predominantly affected by the in situ strength of carbon fibers as well as the relationship between the surface characteristics of carbon fibers and the material interface. T300 composites failed in a brittle mode, whereas T700 composites displayed a non-brittle fracture behavior. Mechanical properties of both composites were improved by PyC interphase. T700 composites with PyC interphase had a homogenous fiber-matrix structure and exhibited the optimum mechanical property, with the flexural strength, flexural modulus and shear strength of 425±23MPa, 37±3GPa and 24±2MPa, respectively.