碳热还原杂化前驱体合成SiC-TaC纳米复合粉体

以五氯化钽(TaCl5)、正硅酸乙酯(TEOS)和葡萄糖(C6H12O6 H2O)为原料制备了葡萄糖复合凝胶,凝胶经过450℃煅烧得到C-SiO2-Ta2O5杂化前驱体,通过碳热还原前驱体,于1200～1500℃合成了SiC-TaC纳米复合粉体,并用X射线衍射扫描电镜和能谱仪对产物进行表征。结果表明:凝胶中无定型的SiO2和Ta2O5可通过Si—O—Ta键合,均匀分布的Si—O—Ta—C长链使得杂化前驱体内部结合成为牢固的互穿网络结构;TaC于1200℃时得到,而SiC可在1400℃开始合成,反应可在1500℃完成。在不同的钽硅摩尔比下,SiC-TaC纳米复合粉体具有差异性形貌。当钽硅比约为0.02时,SiC与TaC纳米晶粒颗粒分布均匀,同质化明显。随着钽硅比的升高,SiC有从球状转变为纳米线状的趋势。

Synthesis of SiC-TaC Nanopowder with Hybrid Precursor via Carbonthermal Reduction

A compound gel was firstly prepared with tantalum pentachloride(TaCl5),tetraethoxysilane(TEOS) and glucose(C6H12O6? H2O) as starting materials,and the gel was then calcined at 450 ℃ to obtain a C-SiO2-Ta2O5 hybrid precursor.A nanopowder of SiC-TaC was synthesized with the precusor via the carbonthermal reduction at 1 200-1 500 ℃.The products were charaterized by using X-ray diffration,scanning electron microscope,energy dispersive.The results show that the amorphous SiO2 and Ta2O5 can be composed by Si-O-Ta bonding,and the evenly-distributed Si-O-Ta-C long chain renders the solid structure of interpenetrating networks inside the hybrid precursor.TaC was obtained at <1 200 ℃,and SiC started to be synthesized at 1 400 ℃,and the whole reaction process could be fully completed at 1 500 ℃.The nanopowder of SiC-TaC presented distinct features at different mole ratios of tantalum to silicon.The particle size distribution of the powder appeared narrower at a mole ratio of tantalum to silicon of 0.02.The morphology of SiC could vary from spherical nanoparticles into curve-shaped nanowires when the mole ratio increased.