Papers by Author: Jun Wang

Abstract: In this paper, effect of heat treatment on the SSA of Si-C-O fibers was investigated and morphologies of the treated fibers were studied using SEM. The results revealed that weight loss was proportional to the treatment time at 1573K and the specific surface area (SSA) increased sharply when the weight loss reached above 6wt%. A rough and porous ceramic fiber with SSA of 23.76m2/g could be obtained at the weight loss of 9.1wt%, as a result of the treatment at 1573K for 32h.

Abstract: In the preparation of polymer-derived SiC fibers, nanochannels are believed to be formed in the early pyrolysis stages due to loss of large volumes of pyrolysis gases. In this paper, small angle X-ray scattering (SAXS) was applied to the characterization and calculation of nanochannels in partiallypyrolyzed SiC fibers. The SAXS measurements showed that nanochannels with a radius of 1.0-20 nm were formed for fibers heat-treated at 973K and 1173K. But their distributions were not continuous and at lower part of the distribution, a peak value was observed at about 1.2nm. This means if the nanochannels are finely controlled, the partially-pyrolyzed SiC fibers have great potential application in the fields of hydrogen storage, gas separation, and so on.

Abstract: Continuous SiC fiber reinforced SiC composites were fabricated by PIP route and their microstructures and mechanical properties were characterized. The density, flexural strength and fracture toughness of the composites were 1.88 g/cm3, 307 MPa and 8.24 MPa⋅m1/2, respectively. The low mechanical properties were ascribed to low density and strong interfacial bonding. The composites exhibited poor oxidation and thermal shock resistance; however, they showed desirable thermal stability.