Improved mechanical properties of SiC fibers pyrolyzed from polycarbosilane under tension

Abstract

Factors that influence the mechanical properties of polymer-derived SiC fibers vary from the polymer structure to firing conditions, among which firing tension was studied in this paper. Tensile strength, Young's modulus, density, shrinkage and diameter were recorded as characteristics of SiC fibers obtained under different tensions and a great improvement of tensile strength, from 1.70GPa to 1.90GPa, could be achieved by using an optimal two-step tension schedule. From the SEM and XRD analysis, we believe that firing tension has two ways to improve the mechanical properties of SiC fibers; one is to eliminate bend portions and the other, to slightly induce the crystallization.