Basic Research On The Fabrication Of Si-C-O Ceramic Fibers Derived From Silicon Resin

In recent years,ceramic matrix composites(CMCs)with low-cost have been urgently needed in aerospace and other fields,and the preparation of low-cost ceramic fibers is one of the bottlenecks that restrict the development of CMCs.Because of the high price of SiC fibers,the research of preparing low cost ceramic fibers from cheap precursors has been paid more and more attention by researchers all over the world.Si-C-O ceramic fibers have not only high mechanical strength,but also excellent temperature resistance and low production cost,which attract wide attention.In this study,the basic research on the preparation of Si-C-O ceramic fibers with low cost and high performance is carried out.Si-C-O ceramic fibers were prepared by using silicon resin SR8803 as precursor.The results showed that SR8803 was an oligomer with Si-O-Si bonds in the main chain.The amorphous Si-C-O ceramics were obtained after heat treatment at 1000oC and the ceramic yield was 79.5wt%.SR8803 had excellent spinning properties,after the optimization of process,the spinning time was over 30min.The curing process was realized by UV crosslinking technology,with the gel content of the cured fibers reaching 92.1wt%.After pyrolyzed at 1000~oC,the Si-C-O ceramic fibers were obtained,which exhibited good flexibility with 6.9?m in diameter,0.80GPa in tensile strength and 99.45GPa in elastic modulus.The fibers showed good heat resistance.The strength of the fibers did not change significantly after being treated for 2h at 1300~oC in nitrogen.The strength began to decrease after being treated at 1400 ~oC,with the strength retention rate of 67.5%.After being treated at 1500~oC,the strength retention rate was only 26.3%.The mechanical properties of Si-C-O ceramic fibers were effectively improved by using precursors which were prepared by physical blending using SR8803 and LPCS.When the ratio of SR8803 to LPCS was 2:1,by using UV curing,the tensile strength and elastic modulus of the obtained Si-C-O ceramic fibers were 0.97GPa and110.41GPa,respectively.When the ratio of SR8803 to LPCS was 1:1,by using EB curing,the tensile strength and elastic modulus of the obtained Si-C-O ceramic fibers were 1.65GPa and 150.27GPa,respectively.The two fibers showed good heat resistance.In nitrogen atmosphere,after treated at 1300~oC for 2h,the strength retention rates of the fibers were 94.8%and 99.4%,respectively.The mechanical properties began to decline under higher temperature.The strength retention rates were respectively 70.1%and 83.0%at 1400~oC,which were 30.9%and 37.6%at 1500~oC,respectively.The tensile strength of quartz fibers was 0.94GPa after treated at 1000~oC,and the maximum usage temperature was no more than 1200~oC.Compared with quartz fibers,the Si-C-O ceramic fibers prepared in this paper had better mechanical strength and heat resistance.