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以聚碳硅烷(polycarbosilane,PCS)为原料,在含氧气(1%)的气氛下用电子束低剂量辐照PCS原丝,然后在惰性气氛下退火实现不熔化处理并烧成制得碳化硅(SiC)纤维。分析了退火温度对辐照后PCS的氧含量、凝胶含量及化学结构的影响,研究了PCS在含氧气氛下辐照及在惰性气氛下退火所发生的化学反应。结果表明:在辐照过程中,主要是Si—H与O2反应生成Si—OH;在退火过程中,主要是Si—OH缩合脱水生成Si—O—Si交联结构。在1250℃烧成制得的SiC纤维呈芯–壳结构,表壳富氧,而芯部氧含量较低。纤维的平均拉伸强度为2.4GPa,平均弹性模量为170.1GPa。
Using polycarbosilane (PCS) as raw material, the PCS precursor was irradiated with low dose electron beam under the atmosphere of oxygen (1%), and then annealed in an inert atmosphere to achieve a non-melting treatment and firing to obtain silicon carbide (SiC) fiber. The effects of annealing temperature on the oxygen content, gel content and chemical structure of irradiated PCS were analyzed. The chemical reactions of PCS irradiated in an oxygen-containing atmosphere and annealing in an inert atmosphere were studied. The results show that during the irradiation process, Si-H mainly reacts with O2 to form Si-OH. During annealing, Si-OH is mainly condensed and dehydrated to form Si-O-Si cross-linked structure. The SiC fiber prepared by sintering at 1250 ℃ has a core-shell structure with oxygen enrichment in the case and low oxygen content in the core. The fiber had an average tensile strength of 2.4 GPa and an average modulus of elasticity of 170.1 GPa.