Preparation of Binary Alloy Powder of Co and Ni by Reduction of Simultaneous-precipitates

Abstract

For the purpose of pre-paring Co-Ni alloy powder, the solid solution of hydroxides of Co and Ni, Co1-xNix (OH)2, were prepared by simultaneous-precipitation from mixture of aqueous solution of Co(NO3)2⋅6H2O and Ni(NO3)2⋅6H2O with 0.1N-NH4OH at 85°C and then these precipitates were reduced in hydrogen at various temperatures ranging from 300°C to 700°C. Analysis of crystal structure by X-ray and electron diffraction and chemical analysis of polarograph showed that the precipitates were solid solution of Co(OH)2 and Ni(OH)2 and their composition also corresponded to the mixed ratio of the nitrates of Co and Ni. From thermomagnetic analysis, the alloy powders reduced were homogeneous solid solution of Co and Ni with composition corresponded to the raw materials respectively. Observation of morphological properties of these powders by electron microscope showed that alloy powders consisted of the smallest unit particles which were linked up with each other, resulting formation of aggregates resembled in shape with original crystals of their mother salts. The size of the unit particles increased with increasing temperature of reduction. Metal-lographical phases of alloy powders prepared were obeerved by X-ray diffraction.