含钽炭基复合材料前驱体的制备及表征

Preparation and characterization of a tantalum-containing pitch precursor for carbon materials

以煤沥青为原料,氯化钽为钽源,通过化学反应制备了含钽沥青前驱体。利用扫描电镜(背散射电子能谱和X射线能量色散谱)、透射电镜、x射线衍射等测试分析手段对钽化合物在沥青中的存在形态、分散状况和热处理过程中的物相变化进行了研究。结果表明:沥青中钽化合物的粒度为20nm～50nm,主要以五氧化二钽的形式均匀分散于沥青中;惰性气氛下,较低温度(420℃)热处理时,钽化合物以δ-Ta2O5的形式存在,温度升高到900℃时,δ-Ta2O5转化为β-Ta2O5,在温度达到1200℃时,β-Ta2O5和碳化钽共同存在于炭基体中,在2800℃温度下,钽完全转化为碳化钽。

Tantalum-containing pitch as a carbon precursor was synthesized by an in situ liquid phase reaction between coal tar pitch and tantalum pentachloride. The dispersion, chemical state and transformation of tantalum during carbonization and graphitization were characterized by scanning electron microscopy, transmission electron microscopy and X-ray diffraction measurements. Also, the effects of the amount of tantalum pentachloride and reaction time on the softening point of the pitch were investigated. Results showed that the tantalum particles were dispersed homogeneously in the pitch precursor with sizes in the range of 20-50 nm. The tantalum particles mainly existed in the form of δ-Ta2O5 when the reaction temperature was 420 ℃. By further heat treatment, δ- Ta2O5 was transformed into β-Ta2O5 at 900 ℃. β-Ta2O5 and TaC co-existed at 1200℃. At 2800 ℃, all the tantalum was transformed into TaC.