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利用共沉淀-热分解法,制备出超细复合碱式碳酸盐前驱体和Co-Cr-V复合金属粉末。利用X线衍射仪和红外吸收光谱分析前驱体和复合金属粉末的物相与晶体结构,用电感耦合等离子体原子发射光谱测定复合金属粉末的元素组成和含量。研究结果表明:前驱体为单相碱式碳酸钴,煅烧得到包含α-Co(fcc)和β-Co(hcp)的两相Co-Cr-V复合金属粉末,其中α-Co相含量在pH为11时达到最大值,约为82%(质量分数)。通过DSC-TG(氩气气氛)分析,研究前驱体的热分解行为,发现前驱体的热分解过程与碱式碳酸钴相似,大约在259和951℃分别发生一次和二次离解。利用扫描电镜观察前驱体和复合金属粉末的形貌,发现煅烧后的复合金属粉末与前驱体的形貌相似,具有继承性,均为类球状颗粒团聚体。利用比表面积分析仪测定前驱体与复合金属粉末的比表面积,并据此估算出粉末的平均粒度:前驱体的粒度在5~11 nm之间,煅烧后得到的复合金属粉末粒度显著增大,接近或达到亚微米级;复合金属粉末粒度随pH(pH在7~11之间)增大而增大,当pH为7时,粉末的平均粒度约为96 nm。
Using coprecipitation-thermal decomposition, ultrafine composite alkali carbonate precursors and Co-Cr-V composite metal powders were prepared. The phase and crystal structure of precursors and composite metal powders were analyzed by X-ray diffraction and infrared absorption spectroscopy. The elemental composition and content of the composite metal powders were determined by inductively coupled plasma atomic emission spectrometry. The results show that the precursor is single-phase basic cobalt carbonate and calcined to obtain a two-phase Co-Cr-V composite metal powder containing α-Co (fcc) and β-Co (hcp) Reaching the maximum value of 11, about 82% (mass fraction). The thermal decomposition behavior of the precursor was investigated by DSC-TG (argon atmosphere). The thermal decomposition of the precursor was similar to that of the basic cobalt carbonate. The first and second dissociation occurred at about 259 and 951 ℃, respectively. Scanning electron microscopy (SEM) was used to observe the morphologies of precursor and composite metal powders. It was found that the morphology of the calcined composite metal powders was similar to that of the precursors, and was inherited as both spherical and spherical aggregates. The specific surface area of the precursor and the composite metal powder is measured by the specific surface area analyzer, and the average particle size of the powder is estimated: the particle size of the precursor is between 5 and 11 nm, the particle size of the composite metal powder obtained after the calcination is significantly increased, Close to or reach the submicron level. The particle size of the composite metal powder increases with the increase of pH (pH between 7 and 11). When the pH is 7, the average particle size of the powder is about 96 nm.