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以Mo Si2和(NH4)6Mo7O24·4H2O为原料,在酸性环境中,采用液相沉淀法制备Mo-Mo Si2前驱体粉末,并对得到的前驱体粉末采用氢气热还原法制备Mo-Mo Si2复合粉末。借助X射线衍射(XRD)、扫描电子显微镜(SEM)和能谱分析(EDS)分析检测手段研究沉积条件(钼源浓度、反应温度、HCl添加量)对前驱体粉末的成分、物相组成与微结构的影响,并分析热还原后所得粉末的物相组成。结果表明:当钼源浓度为0.0142和0.0285 mol·L-1时,前驱体粉末的由Mo O3和Mo Si2两相组成;当钼源浓度增大到0.0570mol·L-1时,前驱体粉末中没有形成Mo O3;随着反应温度的升高或HCl添加量的增加,由六棱柱Mo O3组装而成的微米支状结构的数量逐渐增多,并且团聚程度也随之增加。研究同时发现,在整个前驱体粉末制备过程中,H+的量对Mo O3的形成起决定性的作用。还原后的粉末主要是由Mo和Mo Si2两相组成,同时还含有少量的Mo2C。
The Mo-Mo Si2 precursor powder was prepared by liquid-phase precipitation method using Mo Si2 and (NH4) 6Mo7O24 · 4H2O as raw materials in an acidic environment, and the Mo-Mo Si2 composite was prepared by hydrogen thermal reduction powder. The effects of deposition conditions (molybdenum source concentration, reaction temperature and HCl addition) on the composition, phase composition and phase composition of the precursor powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) The influence of the microstructure and the phase composition of the resulting powder after thermal reduction were analyzed. The results show that when the molybdenum source concentration is 0.0142 and 0.0285 mol·L-1, the precursor powder is composed of two phases, Mo O3 and Mo Si2. When the molybdenum source concentration is increased to 0.0570 mol·L-1, the precursor powder MoO3 was not formed. With the increase of reaction temperature or the addition of HCl, the number of micro-branched structures assembled by hexagonal Mo O3 gradually increased, and the degree of agglomeration also increased. The study also found that the amount of H + plays a decisive role in the formation of MoO3 throughout the preparation of the precursor powder. The reduced powder is mainly composed of Mo and Mo Si2 two phases, but also contains a small amount of Mo2C.