High-temperature oxidation is an important property to evaluate thermal protection materials. However, since oxidation is a complex process involving microstructure evolution, its quantitative analysis has always been...High-temperature oxidation is an important property to evaluate thermal protection materials. However, since oxidation is a complex process involving microstructure evolution, its quantitative analysis has always been a challenge. In this work, a phase field method （PFM） based on the thermodynamics theory is developed to simulate the oxidation behavior and oxidation induced growth stress. It involves microstructure evolution and solves the problem of quantitatively computational analysis for the oxidation behavior and growth stress. Employing this method, the diffusion process, oxidation performance, and stress evolution axe predicted for Fe-Cr-A1-Y alloys. The numerical results agree well with the experimental data. The linear relationship between the maximum growth stress and the environment oxygen concentration is found. PFM provides a powerful tool to investigate high-temperature oxidation in complex environments.展开更多
The NiFe2O4-10NiO powder for inert anode of aluminium electrolysis was prepared by high temperature solid state reaction. The microstructural evolution from the raw materials NiO and Fe2O3 to the NiFe2O4-10NiO powder ...The NiFe2O4-10NiO powder for inert anode of aluminium electrolysis was prepared by high temperature solid state reaction. The microstructural evolution from the raw materials NiO and Fe2O3 to the NiFe2O4-10NiO powder was studied by SEM. The results show that the domain structure making up of the agglomerate particles of Fe2O3 remains after high temperature solid state reaction, and the diffusion of Ni2+ into Fe2O3 structure is the control step of the reaction process. A microstructure with compact structure and fine grain inside the particle results from the sintering of NiFe2O4-10NiO powder.展开更多
The effect of F,K,and Na on the solid phase reaction of the Baiyunebo iron ore was investigated by differential thermal analysis （DTA） and X-ray diffraction（XRD）.It has been identified that alkaline elements K and...The effect of F,K,and Na on the solid phase reaction of the Baiyunebo iron ore was investigated by differential thermal analysis （DTA） and X-ray diffraction（XRD）.It has been identified that alkaline elements K and Na in the Baiyunebo ore instigate the formation of low melting point compounds Na2SiO3 and Na2O·Fe2O3 and the generation of molten state in the solid phase sintering.Element F in the Baiyunebo ore facilitates the formation of cuspidine compound 3CaO·2SiO2·CaF2 in the solid phase reaction.The cuspidine compound is kept in solid as one of the final products through the entire sintering process due to its high melting point.In the sintering process,CaF2and SiO2 react with CaO first and form 3CaO·2SiO2·CaF2 and 3CaO·2SiO2,so the formation of ferrites,Na2O·Fe2O3,and 2CaO·Fe2O3 is inhibited.展开更多
基金Project supported by the National Natural Science Foundation of China (Nos. 90505015 and10702035)
文摘High-temperature oxidation is an important property to evaluate thermal protection materials. However, since oxidation is a complex process involving microstructure evolution, its quantitative analysis has always been a challenge. In this work, a phase field method （PFM） based on the thermodynamics theory is developed to simulate the oxidation behavior and oxidation induced growth stress. It involves microstructure evolution and solves the problem of quantitatively computational analysis for the oxidation behavior and growth stress. Employing this method, the diffusion process, oxidation performance, and stress evolution axe predicted for Fe-Cr-A1-Y alloys. The numerical results agree well with the experimental data. The linear relationship between the maximum growth stress and the environment oxygen concentration is found. PFM provides a powerful tool to investigate high-temperature oxidation in complex environments.
基金Project(2005CB623703) supported by the National Basic Research Program of China
文摘The NiFe2O4-10NiO powder for inert anode of aluminium electrolysis was prepared by high temperature solid state reaction. The microstructural evolution from the raw materials NiO and Fe2O3 to the NiFe2O4-10NiO powder was studied by SEM. The results show that the domain structure making up of the agglomerate particles of Fe2O3 remains after high temperature solid state reaction, and the diffusion of Ni2+ into Fe2O3 structure is the control step of the reaction process. A microstructure with compact structure and fine grain inside the particle results from the sintering of NiFe2O4-10NiO powder.
基金supported by the National Natural Science Foundation of China(No.50664006)
文摘The effect of F,K,and Na on the solid phase reaction of the Baiyunebo iron ore was investigated by differential thermal analysis （DTA） and X-ray diffraction（XRD）.It has been identified that alkaline elements K and Na in the Baiyunebo ore instigate the formation of low melting point compounds Na2SiO3 and Na2O·Fe2O3 and the generation of molten state in the solid phase sintering.Element F in the Baiyunebo ore facilitates the formation of cuspidine compound 3CaO·2SiO2·CaF2 in the solid phase reaction.The cuspidine compound is kept in solid as one of the final products through the entire sintering process due to its high melting point.In the sintering process,CaF2and SiO2 react with CaO first and form 3CaO·2SiO2·CaF2 and 3CaO·2SiO2,so the formation of ferrites,Na2O·Fe2O3,and 2CaO·Fe2O3 is inhibited.
