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Home  >  Journal list  >  MATERIALS TRANSACTIONS  >  Vol.49  No.2 (2008)  >  pp.352-359

MATERIALS TRANSACTIONS
<<Previous article Vol.49  No.2 (2008)   pp.352 - 359 Next article>>

Low Temperature Isothermal Reduction Kinetics of Fe2O3/NiO Mixed Oxides and Comparative Synthesis of Fe1−xNix Alloys

Jong-Jin Pak1), M. Bahgat1), Bo-Ho Kim1) and Min-Kyu Paek1)
1) Department of Metallurgical and Materials Eng., Hanyang University

Two Molar ratios 1:1 and 1:2 of AR grade nickel oxide and iron oxide powder was mixed and compacted. The fired compacts were isothermally reduced in pure hydrogen at 500, 550, 600 and 650°C. Based on thermogravimetric analysis, the reduction behavior and kinetics reaction mechanism were studied comparatively for the different mixed oxides ratios. The initial fired powder and the various reduction products were characterized by XRD, SEM, TEM and reflected light microscope to reveal the effect of hydrogen reduction on composition and microstructure of produced Ferronickel alloy. Synthesis of nanocrystalline Fe1−xNix alloy with 33 and 20 at% Ni for reduction of 1:1 and 1:2 NiO/Fe2O3 ratios was detected respectively. The activation energy values were calculated from Arrhenius equation and the approved mathematical formulations for the gas solid reaction were applied. It was found that for NiO/Fe2O3 of both 1:1 and 1:2 ratios, the initial reduction stages is controlled by the combined gaseous diffusion and interfacial chemical reaction mechanisms while at the final reduction stages the reaction is controlled by the interfacial chemical reaction mechanism.


Keyword:
Fe2O3/NiO, H2-reduction, nanocrystallites, iron-nickel alloy, fcc-alloy, bcc-alloy

Received: August 20, 2007
Accepted: November 12, 2007 , Published online: January 25, 2008
Copyright (c) 2008 The Japan Institute of Metals

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