Kinetics of Decomposition and Re-oxidation Resistance of θ- and χ-Iron Carbides at Elevated Temperatures and Influence of Their Formation Conditions
スポンサーリンク
概要
- 論文の詳細を見る
The rate of decomposition of θ-iron carbide (Fe3C) and χ-iron carbide (Fe5C2), which were produced by carburizing reduced iron from a hematite ore and a limonite ore with 80%CO-H2-H2S mixture of aS=0.5, was determined from their compositional change. Their decomposition starts from about 873 K with Fe5C2 and about 973 K with Fe3C. To mass fraction variation curves of θ- and χ-iron carbide, the integrated rate equation for the first order reaction was applied to obtain the rate constant, k. The value of k for Fe5C2 is much greater than that for Fe3C. Fe5C2 firstly decomposes to Fe3C plus carbon and secondly the formed Fe3C decomposes to metallic iron plus carbon. Microscopically, the metallic iron grows as if the flat interface between Fe3C and metallic iron propagates through the grain of Fe3C. And the iron carbide and formed metallic iron are always in front of pore. Therefore, the gas molecules in the atmosphere can react with the carbide, metallic iron and carbon throughout the reaction. The re-oxidation in dry air accelerated by the exothermic reaction for both iron carbides begins from about 623 K. The reason why the re-oxidation starts at the lower temperature than the decomposition does is direct oxidation of Fe5C2 and Fe3C to iron oxides and CO2 before their decomposition. The re-oxidation starting temperature is raised by the increase of the temperature of reduction and carburization, but the improvement is not very large.
- 社団法人 日本鉄鋼協会の論文
- 2004-02-15
著者
-
IGUCHI Yoshiaki
Nagoya Institute of Technology
-
Kouda Takafumi
Graduate School Nagoya Institute Of Technology
-
Shibata Toshihiro
Graduate School Nagoya Institute Of Technology
関連論文
- Influence of sulfur activity on the reforming reaction during production of iron carbide with CO-CH_4-H_2-H_2S mixtures in fluidized bed
- Electronic Transport Properties of ZrTiO_4 at High Temperature ( FERROELECTRIC MATERIALS AND THEIR APPLICATIONS)
- Carburized Carbon Content of Reduced Iron and Direct Carburization in Carbon Composite Iron Ore Pellets Heated at Elevated Temperature
- Abnormal Swelling during Reduction of Binder Bonded Iron Ore Pellets with CO-CO_2 Gas Mixtures
- Reduction and Melting Process of Coal Char/Iron Ore Composite Pellet by Heating in Nitrogen
- Chromites Reduction Reaction Mechanisms in Carbon-Chromites Composite Agglomerates at 1773K
- Rate of Iron Carbide Formation from Reduced Iron in CO-H_2-H_2S Mixtures under Pressurized Conditions
- Kinetics of Decomposition and Re-oxidation Resistance of θ- and χ-Iron Carbides at Elevated Temperatures and Influence of Their Formation Conditions
- Carburization Kinetics of Reduced Iron during Its Carbidization in CO-H_2-H_2O-H_2S Mixtures
- Reactions, Coalescence of Reduced Iron Particles, and Liberation of Carbon Particles in Carbon Composite Iron Ore Pellets
- Kinetics of the Reactions in Carbon Composite Iron Ore Pellets under Various Pressures from Vacuum to 0.1MPa
- Kinetics of Cementite Formation from Reduced Iron in CO-H_2-H_2S Mixtures under Pressurized Conditions
- Sulfur Sorption Rate and Equilibrium Content of Reduced Iron in H_2-H_2S Mixtures