The Study On External Addition Of CeO₂ In Oxide Metallurgy

The application of external addition method in oxide metallurgy has attracted wide attention from metallurgy workers.In recent years,most of the research has focused on titanium oxides which have better wettability and reactivity.Although Ce-containing oxides can effectively induce Intragranular Ferrite（IGF）nucleation,there are few studies on the external addition of cerium oxides.Therefore,this thesis focus on CeO₂particles which modified by mechanochemical method to explore the influence of external CeO₂particles on inclusions and microstructure.The results are helpful for expanding the application of CeO₂in oxide metallurgy.Firstly,CeO₂particles were ball-milled with Fe powder,Ti O₂and Si powder,respectively.Then each mixture were added to molten steel to explore the feasibility of introducing CeO₂particles.The results show that Ce-Al-O-Mn-S composite inclusions can be formed after the adding of CeO₂particles wrapped with Si powder,which can effectively induce the nucleation of IGF.The analysis indicates that Si powder coating layer can effectively disperse the CeO₂particles.Furthermore,the molten Si can improve the wettability between CeO₂and molten steel,thereby enhancing their reactivity.Secondly,steel samples added with different contents of Si powder and CeO₂particles were systematically studied.The experimental results show that under this conditions,the optimum addition amount of modifier Si powder is 10g,and the optimum ratio of Si powder and CeO₂addition amount is 1:2.When the ratio is greater than 1:2,the ability of Si powder to improve the wettability of CeO₂and molten steel tends to be stable.In addition,too much Si adding will introduce a large number of Si-containing inclusions.When the ratio is less than 1:2,the modifier cannot disperse CeO₂particles effectively.Thus the improvement of wettability between CeO₂and molten steel is poor,which reduces the effectiveness of CeO₂adding.Thirdly,the effect of particle size on the addition of CeO₂was studied.The results show that the Ce content and proportion of Ce-containing oxides in the samples added with nano-scale CeO₂are generally higher than those of micro-scale CeO₂.Moreover,the smaller particle size of external addition of CeO₂results in the better refinement of steel inclusion.The analysis shows that the high energy of nano-sized particles is the main factor.