先驱体转化法制备含硼SiC纤维  

Preparation of Polymer-Derived Boron-Containing Silicon Carbide Fibers

作　　者：许憨 张力 陆雪川 陈立富[1] 

机构地区：[1]高性能陶瓷纤维教育部重点实验室,厦门大学材料学院材料科学与工程系,福建厦门361005

出　　处：《硅酸盐学报》2011年第8期1260-1267,共8页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(51072169)资助项目

摘　　要：通过二甲基胺硼烷(dimethylamine borane,DMAB)与低分子量聚碳硅烷(low-molecular mass polycarbosilane,LPCS)反应合成硼溶胶,将硼溶胶与高分子量聚碳硅烷(high-molecular mass polycarbosilane,HPCS)共混制备含硼聚碳硅烷先驱体,经熔融纺丝、氧化交联、热解以及1 800℃烧结制备含硼碳化硅纤维(SiC-B),研究了硼溶胶的形成过程以及SiC-B纤维的组成与性能,结果表明:由于Si—H键和B—H键的相互作用,LPCS与DMAB发生反应,实现LPCS的化学交联,从而形成高分散、高稳定的硼溶胶;硼的引入有效抑制了高温烧结过程中SiC晶粒长大,显著提高了纤维的致密度和力学性能;经1 800℃烧结后,SiC-B纤维表面光滑、断面致密,纤维平均拉伸强度为0.8 GPa。X射线衍射结果显示:SiC-B纤维的主要晶相为β-SiC和少量α-SiC,β-SiC的平均晶粒尺寸约为17.8 nm。Dimethylamine borane（DMAB） was reacted with low-molecular mass polycarbosilane（LPCS） to form a boron-containing colloid.The colloid was then added into a high-molecular mass polycarbosilane（HPCS） to form a boron-containing polycarbosilane precursor.The precursor was melt-spun,oxidation cured,pyrolyzed and sintered at 1 800 ℃ to obtain boron-containing silicon carbide（SiC-B） fibers.Formation of the colloid as well as the composition and performance of SiC-B fibers were studied.Results show that the interaction between Si—H bond and B—H bond is responsible for the reaction of DMAB and LPCS,resulting in the chemical cross-linking of LPCS,and hence forming well-dispersed and highly-stable boron-containing colloids.Introduction of boron could effectively inhibit a rapid growth of SiC grains during sintering,improving fiber density and tensile strength.Surface of SiC-B fibers sintered at 1 800 ℃ is smooth and fracture surface is dense.Average tensile strength of SiC-B fibers is 0.8 GPa.Results by X-ray diffrac-tion indicate that SiC-B fibers consist of mainly β-SiC crystals and a small amount of α-SiC.The average grain size of β-SiC is 17.8 nm.

关 键 词：二甲基胺硼烷 溶胶 先驱体 碳化硅纤维 

分 类 号：TQ343[化学工程—化纤工业]