Electrochemical Measurement And Analysis Of The Kinetics Of Aluminum Deoxidation In Molten Iron

It is very important to study the mechanism of aluminum deoxidation and inclusion formation for the optimization of steelmaking process and inclusion control.At present,the group has calculated the cluster structure and thermodynamic properties of the intermediate products of aluminum oxide reaction by using the first principle,explained and demonstrated the two-step mechanism of alumina inclusion nucleation and clarified the nucleation path.On the basis of the two-step nucleation mechanism of inclusions,the kinetic information of aluminum deoxidation in Fe-Al-O melts is detected on-line by electrochemical method and the kinetic curve is analyzed in this paper.The main work is as follows:?1?Using the partial stable zirconia MSZ solid electrolyte at high temperature with selective permeability to oxygen ions,using CO/CO₂(p_co/p_co2=5/1)as the reference gas,an electrochemical workstation was used to connect the reference gas with the Fe based melt to form a solid electrolyte molten iron reaction interface.three experiments of adding 0.1%?Mass percentage?aluminum before connecting the electrochemical workstation and 0.05%?Mass percentage?and 0.02%?Mass percentage?aluminum after connecting the electrochemical workstation were carried out.Based on the principle that the oxygen potential difference between the reference gas and the molten iron drives the migration of oxygen ions,the change of open circuit voltage with time at both ends is measured by electrochemical workstation.Based on the curve of open circuit voltage,the curve of oxygen concentration at the interface between solid electrolyte and molten iron was calculated by Nernst equation.The interface between solid electrolyte and molten iron was observed by SEM,which proved the existence of alumina inclusions.?2?By analyzing the oxygen concentration curve at the interface of solid electrolyte and molten iron,the instantaneous rate of oxygen concentration consumption in aluminum oxygen reaction is obtained;furthermore,the reaction order a of oxygen in the rate equation of aluminum deoxidation v=kc_Al^?c_O^? was calculated by isolation method,the rate formula of aluminum deoxidation expressed by oxygen concentration is v_O=k'_Oc_O^?,in style,k'_O=kc_<sup>Al^?,the oxygen reaction orders a of 0.05%?Mass percentage?and 0.02%?Mass percentage?with aluminum is about 3 and 7,respectively.?3?By using Fick's second law to analyze the oxygen concentration curve at the interface between solid electrolyte and molten iron,the diffusion equation of oxygen element in molten iron in aluminum deoxidization is obtained:???,in the formula,DO is the diffusion coefficient of oxygen,and Do with 0.1%?Mass percentage?,0.05%?Mass percentage?and 0.02%?Mass percentage?aluminum is 8.893×10-4 cm²/s,2.034×10-3cm²/s,8.234×10-3cm²/s,respectively.?4?According to the rate formula of oxygen derived above under different speed control links deduced above,the total rate equation of aluminum deoxidation reaction expressed by oxygen concentration is v_Oc_O,1^?+c_O,1-c_O,2/?/D_O+1/k'_O.