Ti-stabilized 321 stainless steel was prepared using an electric arc furnace, argon oxygen decarburization (AOD) furnace, ladle furnace (LF), and continuous casting processes. In addition, the effect of refining proce...Ti-stabilized 321 stainless steel was prepared using an electric arc furnace, argon oxygen decarburization (AOD) furnace, ladle furnace (LF), and continuous casting processes. In addition, the effect of refining process and utilization of different slags on the evolution of inclusions, titanium yield, and oxygen content was systematically investigated by experimental and thermodynamic analysis. The results reveal that the total oxygen content (TO) and inclusion density decreased during the refining process. The spherical CaO–SiO2–Al2O3–MgO inclusions existed in the 321 stainless steel after the AOD process. Moreover, prior to the Ti addition, the spherical CaO–Al2O3–MgO–SiO2 inclusions were observed during LF refining pro-cess. However, Ti addition resulted in multilayer CaO–Al2O3–MgO–TiOx inclusions. Two different samples were prepared by conventional CaO–Al2O3-based slag (Heat-1) and -TiO2-rich CaO–Al2O3-based slag (Heat-2). The statistical analysis revealed that the density of inclusions and the -TiOx content in CaO–Al2O3–MgO–TiOx inclusions found in Heat-2 sample are much lower than those in the Heat-1 sample. Furthermore, the TO content and Ti yield during the LF refining process were controlled by using -TiO2-rich calcium aluminate synthetic slag. These results were consistent with the ion–molecule coexist-ence theory and FactSage?7.2 software calculations. When -TiO2-rich CaO–Al2O3-based slag was used, the -TiO2 activity of the slag increased, and the equilibrium oxygen content significantly decreased from the AOD to LF processes. Therefore, the higher -TiO2 activity of slag and lower equilibrium oxygen content suppressed the undesirable reactions between Ti and O.展开更多
采用喷雾干燥法和沉淀法,制备了表面修饰TiO2（B）（2wt%、4wt%、6wt%和8wt%）的富锂层状氧化物Li（Li0.17Ni0.2Mn0.58Co0.05）O2正极材料。X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）结构测试分析结果表明,修饰T...采用喷雾干燥法和沉淀法,制备了表面修饰TiO2（B）（2wt%、4wt%、6wt%和8wt%）的富锂层状氧化物Li（Li0.17Ni0.2Mn0.58Co0.05）O2正极材料。X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）结构测试分析结果表明,修饰TiO2（B）后样品的体相结构仍然保持初始样品的层状结构,仅氧化物颗粒表面附着有少量TiO2（B）纳米晶。示差扫描量热测试（DSC）表明,与初始样品比较,修饰TiO2（B）后样品的热稳定性得到明显改善。在2.0~4.8 V范围内进行恒流电化学性能测试。研究显示,在0.1C（1C=300 m A/g）倍率下,修饰4wt%TiO2（B）样品的首次放电比容量可达296.4 m Ah/g,首次库伦效率则由初始样品的77.7%提升到修饰TiO2（B）后样品的84.3%,100周循环后电极容量保持率由初始样品的69.5%提升到修饰TiO2（B）后样品的80.2%。即使在阶梯倍率的2C倍率下,修饰4wt%TiO2（B）的样品仍具有较高的电化学容量（166.5 m Ah/g）。以上研究结果表明,表面修饰TiO2（B）纳米晶可以显著改善富锂层状氧化物Li（Li0.17Ni0.2Mn0.58Co0.05）O2的热稳定性和电化学性能。展开更多
基金The authors gratcfully acknowledge the sup-port of the National Natural Science Foundation of China(Grant No.51374020)the State Key Laboratory of Advanced Metallurgy at theUniversity of Science and Technology Beijing(USTB)the JiuquanIron and Steel Group Corporation.
文摘Ti-stabilized 321 stainless steel was prepared using an electric arc furnace, argon oxygen decarburization (AOD) furnace, ladle furnace (LF), and continuous casting processes. In addition, the effect of refining process and utilization of different slags on the evolution of inclusions, titanium yield, and oxygen content was systematically investigated by experimental and thermodynamic analysis. The results reveal that the total oxygen content (TO) and inclusion density decreased during the refining process. The spherical CaO–SiO2–Al2O3–MgO inclusions existed in the 321 stainless steel after the AOD process. Moreover, prior to the Ti addition, the spherical CaO–Al2O3–MgO–SiO2 inclusions were observed during LF refining pro-cess. However, Ti addition resulted in multilayer CaO–Al2O3–MgO–TiOx inclusions. Two different samples were prepared by conventional CaO–Al2O3-based slag (Heat-1) and -TiO2-rich CaO–Al2O3-based slag (Heat-2). The statistical analysis revealed that the density of inclusions and the -TiOx content in CaO–Al2O3–MgO–TiOx inclusions found in Heat-2 sample are much lower than those in the Heat-1 sample. Furthermore, the TO content and Ti yield during the LF refining process were controlled by using -TiO2-rich calcium aluminate synthetic slag. These results were consistent with the ion–molecule coexist-ence theory and FactSage?7.2 software calculations. When -TiO2-rich CaO–Al2O3-based slag was used, the -TiO2 activity of the slag increased, and the equilibrium oxygen content significantly decreased from the AOD to LF processes. Therefore, the higher -TiO2 activity of slag and lower equilibrium oxygen content suppressed the undesirable reactions between Ti and O.
文摘采用喷雾干燥法和沉淀法,制备了表面修饰TiO2（B）（2wt%、4wt%、6wt%和8wt%）的富锂层状氧化物Li（Li0.17Ni0.2Mn0.58Co0.05）O2正极材料。X射线衍射（XRD）、扫描电子显微镜（SEM）和透射电子显微镜（TEM）结构测试分析结果表明,修饰TiO2（B）后样品的体相结构仍然保持初始样品的层状结构,仅氧化物颗粒表面附着有少量TiO2（B）纳米晶。示差扫描量热测试（DSC）表明,与初始样品比较,修饰TiO2（B）后样品的热稳定性得到明显改善。在2.0~4.8 V范围内进行恒流电化学性能测试。研究显示,在0.1C（1C=300 m A/g）倍率下,修饰4wt%TiO2（B）样品的首次放电比容量可达296.4 m Ah/g,首次库伦效率则由初始样品的77.7%提升到修饰TiO2（B）后样品的84.3%,100周循环后电极容量保持率由初始样品的69.5%提升到修饰TiO2（B）后样品的80.2%。即使在阶梯倍率的2C倍率下,修饰4wt%TiO2（B）的样品仍具有较高的电化学容量（166.5 m Ah/g）。以上研究结果表明,表面修饰TiO2（B）纳米晶可以显著改善富锂层状氧化物Li（Li0.17Ni0.2Mn0.58Co0.05）O2的热稳定性和电化学性能。
