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.