Decomposition Behavior of Fe3C under Ar Atmosphere

Abstract

Suppression of CO2 discharged from iron and steelmaking companies is an example of the biggest issues for the protection of global environment and sustainable growth of steelmaking industry. One of the efforts made to decrease the emission of CO2 in ironmaking process is blowing of hydrogen gas into blast furnace. Hydrogen gas can reduce iron oxide and form harmless H2O. Cementite (Fe3C) may be formed by introduction of hydrogen into blast furnace and play an important role on carburization and smelting behavior of reduced iron.In the present work, Fe3C sample was held at 800-1 100 K under Ar atmosphere to clarify the stability and the behavior of Fe3C phase. It was confirmed that metastable Fe3C phase will decompose under Ar atmosphere at 800 K and rapidly decompose at temperature over 900 K. Also, it was found that composite of nano-size C and Fe will form when Fe3C decompose.

Stability of Cementite under CO–CO₂–H₂ Gas Mixture at 1200 K

“…It can be seen that Fe and Fe3C peaks exist after the experiment when heated under Ar. As reported in the previous paper, 18) when Fe3C is heated under Ar it will decompose into Fe and C, and nanosize C will be included in metallic Fe phase as composites and some C particle will be flown out from the furnace. By changing the gas from Ar to70vol%CO-30vol%CO2, C content at 0 min holding time changed from 2.30mass%C to 1.03 mass% and this concentration difference is due to the oxidation reaction of C particle by CO2 in gas mixture.…”

“…Addition of H2 to 70vol%CO-30vol%CO2 gas will increase C content in sample after experiment. It was reported in the previous paper 18) that composite of Fe and nanosize C formed by decomposition of Fe3C will rapidly melt. High C content in sample will have positive effect on lowering the smelting temperature of reduced iron in blast furnace.…”

“…[2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] Also, Fe3C is a metastable phase and its decomposition behavior was investigated by one of the authors. 18) It is reported by Satoh et al 2,3) and Gudenau et al 19) that Fe3C may enhance carburization and smelting of reduced iron. Formation of Fe3C in blast furnace may have good influence on CO2 suppression from ironmaking process.…”

Research on Reaction between SiC and Fe₂O₃

“…8, there is no Fe 3 C in the products. The reason is that metastable Fe 3 C phase will decompose into Fe and C under Ar atmosphere at 800 K (527 C) and rapidly decompose at temperature over 900 K (627 C) 10) 3Fe(s) + SiC(s) = Fe 3 Si(s) + C(s)…”

“…The nal products and their corresponding stoichiometric coef cients calculated by FactSage 7.0. CO, 0 10. CO 2 , 1.50 Fe, 0.55 SiO 2 , 0.25 Fe 2 SiO 4 1.00 CO, 2.00 Fe, 1.00 SiO 2 0.60 CO, 0.20 Fe, 1.20 SiO 2 , 0.60 Fe 3 C CO, 1.98 Fe, 1.00 SiO 2 , 0.02 liquid Fe (0.86 Fe, 0.14C) 0.60 CO, 1.20 SiO 2 , 0.52 Fe 3 C, 0.51 liquid Fe (0.84 Fe, 0.16 C) 1423 K 0.60 CO, 1.20 SiO 2 , 0.18 C, 2.42 liquid Fe (0.83 Fe, 0.17 C) 1473 K 0.70 CO, 0.10 CO 2 , 1.50 Fe, 0.45 SiO 2 , 0.84 liquid slag (0.42 SiO 2 , 0.58 FeO) Fig.…”