Silicon Carbide Fibers With Low Oxygen Content Prepared By Dry Spinning

High-molecular-weight polycarbosilane (PCS) fibers, pyrolyzed to silicon carbide (SiC) fibers without air curing, were prepared by dry spinning. This kind of SiC fibers exhibit low oxygen content and high oxidation resisitance.PCS with high Mw (4000~12000) for dry spinning was synthesized by high pressure method. The solvent was selected and solution property (especially rheological property ) was studied. The spinning and burning process were discussed. The surface morphologies, oxygen content, mechanics properties and high oxidation resisitance of SiC fibers were also studied. It was found that the PCS (4000≤Mw≤12000) was produced using the low soft point PCS (160~220℃) when the reaction temperature was above 450℃and initialized pressure was 1MPa; Xylene is the appropriate solvent for PCS; The solubility of PCS is more than 192g/100ml at 20℃and rises as the temperature increasing, the solubility of the PCS with low molecular weight is in evidence larger than the PCS'with high molecular weight at above 65℃; The viscosity increases as the concentration increasing and decreases as the temperature increasing. The influence of concentration and temperature on viscosity is distinct when the concentration is above 67.0wt.% and the temperature is below 45℃.The perfectly viscosity for dry spinning was 18.0~22.0 Pa·s; The PCS fibers (9000