1 School of Materials Science and Engineering, Chongqing University, Chongqing 400044, China 2 Chongqing Key Laboratory of Vanadium–Titanium Metallurgy and Advanced Materials, Chongqing University, Chongqing 400044, China
Phase-field method for growth of iron whiskers in the presence of CO gas convection
1 School of Materials Science and Engineering, Chongqing University, Chongqing 400044, China 2 Chongqing Key Laboratory of Vanadium–Titanium Metallurgy and Advanced Materials, Chongqing University, Chongqing 400044, China
摘要 A phase-field model for growth of iron whiskers that includes convection around a particle was investigated during the process of fluidized pre-reduction. In the simulations, the phase-field method was coupled with flow field and reduction of iron oxide particles. The results showed that the reduction rate at local place had significant effects on the iron ions diffusion and the iron whiskers were more easily grown on the area containing low mole fraction of oxygen. The growth of iron whiskers in the model was investigated in two important simple situations: a velocity change flow and a CO concentration change flow. Because of high reduction rate and low surface energy, iron whiskers were more easily grown on the windward surface and the length of iron whiskers increased with gas velocity increasing. However, both the length and numbers of iron whiskers increased with CO concentration increasing due to the more nucleation site of iron whiskers created by CO adsorbed. When the gas velocity is higher than 0.3 m/s or CO mole fraction is high than 0.6, the nucleation incubation time would be rapidly decreased, which could give suggestions to control the operational parameters in the fluidized pre-reduction process.
Abstract：A phase-field model for growth of iron whiskers that includes convection around a particle was investigated during the process of fluidized pre-reduction. In the simulations, the phase-field method was coupled with flow field and reduction of iron oxide particles. The results showed that the reduction rate at local place had significant effects on the iron ions diffusion and the iron whiskers were more easily grown on the area containing low mole fraction of oxygen. The growth of iron whiskers in the model was investigated in two important simple situations: a velocity change flow and a CO concentration change flow. Because of high reduction rate and low surface energy, iron whiskers were more easily grown on the windward surface and the length of iron whiskers increased with gas velocity increasing. However, both the length and numbers of iron whiskers increased with CO concentration increasing due to the more nucleation site of iron whiskers created by CO adsorbed. When the gas velocity is higher than 0.3 m/s or CO mole fraction is high than 0.6, the nucleation incubation time would be rapidly decreased, which could give suggestions to control the operational parameters in the fluidized pre-reduction process.
Feng Lu,Liang-ying Wen,Xu Han, et al. Phase-field method for growth of iron whiskers in the presence of CO gas convection[J]. Journal of Iron and Steel Research International, 2019, 26(8): 829-837.
2019, Vol. 26 
