Mill Scale for Synthesis of Fe–Ni and Fe–Ni–Co Alloys through Gaseous Reduction: Reaction Kinetics and Mechanism

Abstract

Nickel and Nickel cobalt ferrite powders were prepared through the ceramic route by calcination of a stoichiometric mixture of nickel oxide, cobalt oxide and mill scale as source for iron oxide. The produced ferrites powders were isothermally reduced in pure hydrogen at 800–1100°C. Based on thermogravimetric analysis, the reduction behavior of the synthesized ferrite and the kinetics reaction mechanism were studied. The initial ferrite powder and the various reduction products were characterized by XRD, SEM and reflected light microscope to reveal the effect of hydrogen reduction on composition, microstructure and reaction kinetics of synthesized ferro-alloys. The activation energy values were calculated from Arrhenius equation. The approved mathematical formulations for the gas solid reaction were applied to confirm the estimated rate controlling reaction mechanism. Complete reduction of home made ferrite powder was achieved with synthesize of nanocrystalline Fe–Ni and Fe–Ni–Co alloys.