Preparation And Characterization Of Continuous Silicon Oxycarbide Ceramic Fibers

Silicon oxycarbide(SiOC)ceramic fibers are made by melt spinning,chemical curing and pyrolysis in inert atmosphere using PMSQ as the ceramic precursor.GPC,FT-IR,NMR,RMS,XRD,SEM,TG-DSC and elements analysis were performed on as-spun,cured and pyrolyzed fibers.Tensile strength,density and reflection loss were measured.PMSQ is readily spinnable.The as-spun fibers can be cured using ammonia as the curing reagent.and the gel content is upto 88.1%.The cured fibers are converted into ceramic fibers by pyrolysis in N2 at 850?,giving the ceramic yield of 83.5%.The fiber surface and the fracture surface are smooth and without cracks and obvious defects.After pyrolysis,the Si-O-C ceramic fibers were amorphous with SiO4 and CSiO3 as the major structural units,C2SiO2 and SiC4 as the minor units and essentially no C3SiO structure.SiOC ceramic fibers are composed of Si(41.32?46.71%),H(0.58?1.52%),C(11.65?13.85%),0(45.04?52.90%).The content of H decreases with the pyrolysis temperature while that of C increases.There was free carbon in SiOC fibers with the size of carbon clusters of 1.35?1.4nm.Both tensile strength and density increase with pyrolysis temperatures.The maximum tensile strength is 818MPa,and the density ranges from 1.99g/cm3 to 2.41g/cm3.The SiOC have reflection loss of-10dB with a band width of 1.7GHz,showing microwave absorption ability.