During sintering the vanadium titanomagnetite,TiO2 competes with Fe2O3 for CaO,which inhibits the formation of calcium ferrite(CxF)and affects the sinter quality.In this paper,the diffusion reaction of CaO-Fe2O3-TiO2 system is intuitively studied by preparing CxF/TiO2 diffusion couple.Electron probe and X-ray diffractometer are used to analyze and characterize the products at different positions of the reaction interface.The reaction characteristics of CxF/TiO2 interface are studied at the diffusion temperature of 900～1050℃and the time of 1～4 h.The effects of temperature and time on the types,distribution and morphology of the generated phases are discussed.The results show that the main phases are CxF,CaO·Fe2O3(CF),Fe2O3,CaTiO3 and TiO2 from the CxF-to TiO2-layer,among which perovskite(CaTiO3)is the main product.The thickness of CaTiO3 increases from 8.1 μm to 90.2 μm with the temperature increasing from 900℃to 1 050℃;it increases from 47.4 μm to 121.4 μm with the time increasing from 1 h to 4 h.Meanwhile,the diffusion thickness of CaTiO3 has a good linear relationship with the square root of diffusion time,which indicates that the formation of CaTiO3 is controlled by diffusion process.Furthermore,the formation process of CaTiO3 in CaO-Fe2O3-TiO2 system is explained by vacancy-mediated diffusion mechanism.
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