Synthesis of silicon carbide nanorods from mixture of polymer and sol–gel silica
Synthesis of silicon carbide nanorods from mixture of polymer and sol–gel silica
复制标题
由聚合物和溶胶-凝胶二氧化硅的混合物合成碳化硅纳米棒
DOI：
10.1007/s10853-006-1175-4
复制
发表时间：
2007
影响因子：
4.5
通讯作者：
K. N. Sood
中科院分区：
文献类型：
--
作者：
V. Raman;G. Bhatia;P. Sengupta;A. Srivastava;K. N. Sood
碳化硅具有许多独特的性能，例如高温下的优异强度、耐腐蚀性和抗氧化性[1]。纤维状碳化硅用于开发陶瓷基和金属基复合材料（CMC 和 MMC）[2, 3]。最近，人们对纳米纤维的合成越来越感兴趣，纳米纤维可用于开发纳米复合材料、固态润滑剂、催化剂和磁性装置组件[4]。纳米碳化硅被合成为纳米棒、纳米线、纳米管和纳米纤维[5-8]。可用作增强材料的碳化硅纳米材料通常通过化学气相沉积（CVD）[9]、电弧放电[10]、聚合物共混技术[11]以及碳纳米管与一氧化硅之间的反应[12]来制备。作者还采用并报道了聚合物共混技术来开发沥青基碳纤维 [13, 14]。作者在用聚合物改性的沥青开发碳纤维的过程中发现，聚苯醚-聚苯乙烯（PPO-PS）共混物在纺丝时不会产生纤维，而是产生棒状材料[13]。基于上述研究结果，本研究尝试通过将溶胶-凝胶衍生的二氧化硅与PPO-PS聚合物共混来合成SiC纳米棒。使用市售的 PPO-PS 作为碳源，使用甲基三乙氧基硅烷 [(MTEOS) Lancaster, 98%] 和四乙氧基硅烷 [(TEOS) E’Merck, 98%] 作为二氧化硅源。 PPO-PS 在惰性气氛中于 1000°C 下碳化以确定碳残留物。将PPO-PS溶解在二氯甲烷中并与MTEOS溶胶混合，该溶胶是通过水解MTEOS、水和二氯甲烷的混合物制备的。将混合物充分搅拌约2小时。然后，使含溶胶的聚合物在室温下胶凝，并在 60°C 下干燥，以获得掺有溶胶-凝胶衍生二氧化硅的聚合物，这是碳化硅纳米棒前体。用 TEOS 溶胶重复相同的实验。将如上制备的SiC前体在1000℃下碳化并分析碳和二氧化硅含量。将碳化产物在氩气气氛下进一步加热至1400℃，得到SiC、碳和二氧化硅的混合物。将热解产物(热处理温度＝1400℃)在空气中于800℃下氧化以除去游离碳。通过扫描电子显微镜（SEM，LEO-440）对 PPO–PS+ MTEOS 和 PPO–PS+ TEOS 的碳化、热解和氧化产物进行了表征。还通过透射电子显微镜（TEM，Jeol JEM 2000 CX）对源自 PPO–PS+ MTEOS 衍生二氧化硅的氧化样品进行了表征。前体（PPO–PS+ MTEOS 衍生的 SiO2）和热解样品（热处理温度 = 1400 C）的 FTIR 光谱是使用 Perkin Elmer FTIR 2000 通过 KBr 颗粒法记录的。 X 射线衍射
Silicon carbide possesses many unique properties like superior strength, corrosion and oxidation resistance at elevated temperature [1]. Silicon carbide in the fibrous form is employed for the development of ceramicmatrix and metal-matrix composites (CMCs and MMCs)[2, 3]. Recently there is growing interest in the synthesis of nanofibres, which could be used for the development of nanocomposites, solid-state lubricants, catalysts and components of magnetic devices [4]. Nano silicon carbides are synthesized as nanorods, nanowires, nanotubes and nanofibres [5–8]. Silicon carbide nanomaterials which can be used as reinforcing material are generally prepared by chemical vapor deposition (CVD)[9], arc-discharge [10], polymer blend technique [11] and by reaction between carbon nanotubes and silicon monoxide [12]. The authors had also employed and reported polymer blend technique for the development of pitch based carbon fibres [13, 14]. It was seen by the authors during their efforts to develop carbon fibres from pitches modified with polymers that polyphenylene oxide–polystyrene (PPO–PS) blend does not give fibres on spinning and gives rod like materials [13]. Based on the results of the above studies, attempts have been made in the present investigation to synthesize SiC nanorods by blending sol–gel derived silica with PPO–PS polymer. Commercially available PPO–PS was used as carbon source and methyltriethoxysilane [(MTEOS) Lancaster, 98%] and tetraethoxysilane [(TEOS) E’Merck, 98%] are used as silica source. PPO–PS was carbonized at 1000 C in inert atmosphere to determine carbon residue. PPO–PS was dissolved in dichloromethane and was mixed with MTEOS sol, which was prepared by hydrolyzing a mixture of MTEOS, water and dichloromethane. The mixture was stirred well for about 2 h. The sol-containing polymer was then allowed to gel at room temperature and dried at 60 C to obtain polymer incorporated with sol–gel derived silica, which is the silicon carbide nanorods precursor. The same experiment was repeated with TEOS sol. The SiC precursor prepared as above was carbonized at 1000 C and analyzed for carbon and silica contents. The carbonized product was further heated at 1400 C under argon atmosphere to get a mixture of SiC, carbon and silica.The pyrolysed products (Heat treatment temperature= 1400 C) were oxidised in air at 800 C to remove the free carbon. The carbonized, pyrolysed and oxidized products of PPO–PS+ MTEOS and PPO–PS+ TEOS were characterized by scanning electron microscopy (SEM, LEO-440). The oxidized sample derived from PPO–PS+ MTEOS derived silica was also characterized by transmission electron microscopy (TEM, Jeol JEM 2000 CX). The FTIR spectra of the precursor (PPO–PS+ MTEOS derived SiO2) and the pyrolysed sample(heat treatment temperature= 1400 C) were recorded by KBr pellet method using Perkin Elmer FTIR 2000. X-ray diffraction