共沉淀法制备Co-Y2O3复合粉的热力学分析

Thermodynamic Analysis of Co-Y2O3 Composite Powders Prepared by Coprecipitation Method

摘要:

为了制备球形颗粒的Co粉和实现在Co粉中添加Y2O3的目的，分析了共沉淀法制备Co-Y2O3复合粉前驱体的热力学。通过对Co2 -Y3 -NH3-C2O42--H2O沉淀体系的热力学分析，得到了lg[M]T－pH关系图(M为金属元素)。热力学分析表明：增加草酸根总浓度[C]T和铵根总浓度[N]T会促进Co2 离子的络合，而Y3 离子只受草酸根总浓度[C]T的影响，随着[C]T的升高Y3 离子沉淀率下降。Co2 离子和Y3 离子沉淀的最佳pH值分别为2～2.5和1.5～2.5。当pH值为2.5时，由共沉淀法制备出簇球状Co-Y2O3前驱体，经煅烧和还原后得到球形Co-Y2O3复合粉，其颗粒尺寸约为5μm。

Abstract:

In order to prepare spherical particles of cobalt powders and add Y2O3 into cobalt powders, the preparation thermodynamic of the precursor of Co-Y2O3 composite powders by coprecipitation was analyzed. The lg[M]T-pH diagram was obtained by analyzing the thermodynamics of Co2 -Y3 -NH3-C2O42--H2O precipitation system. It is shown that the complexation of Co2 ions is promoted by increasing the total concentration of oxalic acid root [C]T and ammonium root [N]T could. The precipitation rate of Y3 ion is only influenced by the total concentration of oxalic acid root [C]T and declines with its increase. The optimum pH values for the precipitation of Co2 and Y3 are 2~2.5 and 1.5~2.5, respectively. The precursor of Co-Y2O3 composite powders was prepared by coprecipitation with the pH value of 2.5. The shape of the precursor composite powders is cluster ball with good dispersion. The spherical Co-Y2O3 composite powders with uniform size distribution and the mean particle size of about 5 μm were obtained.