Ferrotitanium is used as a deoxidizer and alloying agent during steelmaking process,which has a high demand for sulfur control.Sulfur was introduced from raw materials in the process of producing ferrotitanium by thermite method,where CaO was used as fluxing agent.At the same time,CaO has a great desulfurization capability.Effects of CaO addition on the distribution of sulfur in high titanium ferroalloy prepared by thermite method were studied in this work.The equilibrium diagram of Ti-AlFe-S system was calculated by FactSage 6.4 software package with FactPS and FTmisc database.The alloy and slag samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),inductively coupled plasma atomic emission spectrometer(ICP-AES),X-ray fluorescence(XRF)and high-frequency infrared ray carbon sulfur analyzer.The result indicates that the sulfur in the alloy firstly exists in the form of liquid FeS,thereafter TiS(s)and eventually Ti2 S(s)during cooling.The sulfur is mainly distributed in the alloy,and only a small amount of sulfur remains in the slag.Moreover,it is noted that the sulfur in the alloy does not distribute homogeneously,and it exists in the form of solid solution phase,(Ti,Al,Fe)S.S content in the slag,the sulfur capacity of the slag and the sulfur distribution ratio(LS)all increase with the increment of CaO addition,while S content in alloys decreases.
分别对Al-TiO_2,Al-V_2O_5,Al-V_2O_5-TiO_2及Al-V_2O_5-TiO_2-CaO体系的热力学和动力学进行了研究.结果表明:采用铝粉直接还原TiO_2,V_2O_5粉末制备Ti-6Al-4V合金是可行的.加入CaO会降低体系单位质量反应热,需要补热才能维持反应进行.Al还原TiO_2的反应在951℃发生,表观活化能E1为166.47 k J/mol,反应级数n1为0.398 2;Al还原V_2O_5的反应在946℃发生,表观活化能E_2为392.72 k J/mol,反应级数n_2为1.061 8.Al粉还原V_2O_5和TiO_2制备Ti-6Al-4V合金体系的反应在1 019℃左右发生,表观活化能E3为173.56 k J/mol,反应级数n3为0.472 2;加入CaO后,反应在979℃左右发生,体系表观活化能升高但反应级数降低.这四个体系均属于液-固反应体系.
