PREPARATION AND CHARACTERIZATION OF FIBROUS Ni-Co ALLOY POWDERS BY THERMAL DECOMPOSITION OF SOLID SOLUTION OF COMPLEX Ni-Co OXALATES

摘要

Synthesis of fibrous Ni-Co alloy powders was achieved by thermal decomposition of precursor of complex Ni-Co oxalates solid solutions obtained via modified coprecipitation method among intimate mixing solution of NiCl{sub}2·6H{sub}2O, CoCl{sub}2·6H{sub}2O and H{sub}2C{sub}2O{sub}4·2H{sub}2O in the presence of surfactant polyvinylpyrrolidone (PVP) and organic solvent ethanol. Scan electron microscopy (SEM), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), disperse energy X-ray analyses (EDX) were used to characterize the structure features and chemical compositions of the as-prepared fibres. The influences of decomposition conditions, including temperature, time, the flow rate of N{sub}2+H{sub}2, and the heating rate, on the morphology, average size and specific surface area of the Ni-Co alloy powders were investigated. It is found that a trend of the mutual alloying of nickel and cobalt: the formation of perfect solid solution for any compositions Ni{sub}xCo{sub}(100-x) was indicated and corresponding Ni{sub}xCo{sub}(100-x) alloys with fcc phase can be obtained under the optimal conditions.