Reduction Kinetics and Catastrophic Swelling of MnO_2-doped Fe_2O_3 Compacts with CO at 1073-1373K

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概要

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• Pure Fe2O3 and Fe2O3 doped with either 2, 4, or 6 mass% MnO2 annealed at 1473 K for 6 h were isothermally reduced with carbon monoxide at 1073–1373 K. The oxygen weight loss resulted from the reduction at a given temperature was continuously recorded as a function of time. Reflected and scanning electron microscopes were used to characterize the annealed and reduced samples whereas the different phases developed were identified by X-ray phase analysis technique. The external volume of partially and completely reduced samples was measured by displacement method and the volume change (ΔV%) was calculated. At a given temperature, the influence of MnO2 mass% on the reduction behaviour and volume change of Fe2O3 compacts was investigated. The doping of MnO2 showed different effects during the reduction of Fe2O3 which is temperature dependant. At <1198 K, the rate of reduction decreased at early stages with the increase in MnO2 mass% due to the presence of hardly reducible manganese ferrite phase (MnFe2O4). At final reduction stages the retardation effect was attributed to the formation of dense iron manganese oxide (FeO0.899, MnO0.101). At ≥1198 K, the presence of MnO2 promoted the reduction of Fe2O3 and the catastrophic swelling resulted from the formation of both metallic iron plates and whiskers was observed. Maximum swelling (ΔV%) was measured at 1198 and at 1248 K for pure Fe2O3 and MnO2-doped compacts respectively and it increased with the increase in MnO2 mass% resulting about 405% for 6 mass% MnO2-doped samples. The reduction mechanism was predicted from the correlation between the apparent activation energy values, testing of different mathematical formulations derived from gas-solid reaction model and the microscopic examination of partially reduced compacts.

• 社団法人 日本鉄鋼協会の論文
• 2007-03-15

著者

• Omar Adel

  Benha High Institute Of Technology Mechanical Engineering Department

• Mousa El-sayed

  Central Metallurgical Research & Development Institute Cmrdi

• EL-GEASSY Abdel-Hady

  Central Metallurgical Research & Development Institute, CMRDI

• NASR Mahmoud

  CMRDI

• MOUSA El-Sayed

  CMRDI

• Nasr Mahmoud

  Central Metallurgical Research & Development Institute Cmrdi

• El-geassy Abdel-hady

  Central Metallurgical Research & Development Institute Cmrdi

関連論文

• Influence of SiO_2 and/or MnO_2 on the Reduction Behaviour and Structure Changes of Fe_2O_3 Compacts with CO Gas
• Reduction Kinetics and Catastrophic Swelling of MnO_2-doped Fe_2O_3 Compacts with CO at 1073-1373K

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