In metallurgical processes, more and more usage of hydrocarbons is encouraged to bring down the carbon emissions. In this regard, numerous investigations on reduction of oxides by C-O-H-N gas mixture have been reporte...In metallurgical processes, more and more usage of hydrocarbons is encouraged to bring down the carbon emissions. In this regard, numerous investigations on reduction of oxides by C-O-H-N gas mixture have been reported. Attempts to simulate these reduction processes using shrinking core model, one of the common models used for such studies, have under predicted the reduction rates. This may be owing to the fact that the homogeneous reaction in the gas phase is not being considered. If the reaction temperatures are above 1,000 K, generally so for many reduction processes, the homogeneous gas reaction rates are expected to be high enough that local equilibrium in the gas phase can be assumed. In the present study, reduction of wustite in a C-O-H-N gas mixture has been modeled using shrinking core model considering the water gas shift equilibrium in the gas while it diffuses through the product layer.展开更多
We investigate the structure,trapping,and diffusion behaviors of helium(He) at vacancy in a Fe single crystal using first-principles simulations.Vacancy with more space can provide the lower electron density region fo...We investigate the structure,trapping,and diffusion behaviors of helium(He) at vacancy in a Fe single crystal using first-principles simulations.Vacancy with more space can provide the lower electron density region for He binding in comparison with intrinsic Fe,causing He to diffuse into the vacancy inner easily.We provide the quantitative microscopic studies related to the atomic-level thermo-kinetic trapping processes.Moreover,such physical viewpoint can be applied to other vacancy-like defects such as vacancy clusters,void and grain boundaries which can open a space with reduced electron density region to increase He binding in metals and metal alloys.展开更多
文摘In metallurgical processes, more and more usage of hydrocarbons is encouraged to bring down the carbon emissions. In this regard, numerous investigations on reduction of oxides by C-O-H-N gas mixture have been reported. Attempts to simulate these reduction processes using shrinking core model, one of the common models used for such studies, have under predicted the reduction rates. This may be owing to the fact that the homogeneous reaction in the gas phase is not being considered. If the reaction temperatures are above 1,000 K, generally so for many reduction processes, the homogeneous gas reaction rates are expected to be high enough that local equilibrium in the gas phase can be assumed. In the present study, reduction of wustite in a C-O-H-N gas mixture has been modeled using shrinking core model considering the water gas shift equilibrium in the gas while it diffuses through the product layer.
基金supported by the National Natural Science Foundation of China (Grant No. 51101135)the Natural Science Foundation of Shandong (Grant No. ZR2010AM002)
文摘We investigate the structure,trapping,and diffusion behaviors of helium(He) at vacancy in a Fe single crystal using first-principles simulations.Vacancy with more space can provide the lower electron density region for He binding in comparison with intrinsic Fe,causing He to diffuse into the vacancy inner easily.We provide the quantitative microscopic studies related to the atomic-level thermo-kinetic trapping processes.Moreover,such physical viewpoint can be applied to other vacancy-like defects such as vacancy clusters,void and grain boundaries which can open a space with reduced electron density region to increase He binding in metals and metal alloys.
