| Aluminum deoxidization is widely used in the process of steelmaking.The study of the reaction mechanism of aluminum deoxidization has an important role in improving the cleanliness of aluminum sedation steel and optimizing the number,size,size distribution and morphology of inclusions.In order to reveal the mechanism of aluminum deoxidation reaction,the migration of oxygen elements in the process of alumina generation and decomposition in Fe-Al-O melt was studied by electrochemical method.First,the preparation method of MSZ(Magnesium Oxide partially stabilized zirconia)solid electrolyte was studied,and the electrical properties of MSZ at high temperature were measured by AC impedance.The results showed that the conductivity of Zr O2 solid electrolyte containing 3.5%Mg O partially stabilized by injection molding increased with the increase of temperature at 1100-1600℃.When the temperature reached 1300℃,the electrical conductivity tended to be stable,and the conductivity was 0.185S/cm at the temperature of 1600 ℃.Second,using the characteristic of MSZ solid electrolyte to conduct oxygen ion in high temperature state,a high temperature melt electrochemistry test device is set up.The Fe-O-Al system is oxygenated by the mixture of the reference gas CO/CO2,and the open circuit voltage is detected by the electrochemical device until the balance is reached.The results showed that: in the process of Al2O3 synthesis,interfacial oxygen concentration with the change of time and increase after transition zone,nucleation zone,Fe-[70ppm Al] system.when the time reaches 2000 s,the oxygen concentration at the interface reaches a stable value,through SEM images were observed Al2O3 inclusions formation at the interface.The supersaturated energy,including interfacial energy and crystallization energy,is required for the Al2O3 inclusions formed at the interface.In the Al2O3 synthesis process,the corresponding energies of Fe-[70ppm Al] and Fe-[30ppm Al] systems are 87KJ/mol and 98KJ/mol,respectively.Third,using the set of high temperature melt electrochemistry test device for FeO and Fe-O-Al system.the external voltage is applied to study the deoxidization process by using Tafel’s theorem and nengster equation to calculate the change of oxygen concentration at the interface.The restrictive links of oxygen in the Fe-Al-O-MSZ system and the kinetics and thermodynamic conditions during the process of Al2O3 deoxidation in this process are discussed in detail.The results show that the external voltage is applied in the electrochemical device in the decomposition of oxide inclusions involves three kinds of dynamic mechanism,are the activation overvoltage,ohmic overvoltage and overvoltage concentration,these mechanisms are restricted link,electrochemical reaction and diffusion of oxygen ions in Zr O2 electrolyte,diffusion of oxygen atoms of iron solution to the interface;the decomposition mechanism of inclusions under the effect of an external voltage,when the external voltage is 0.1-0.3V and the melting oxygen migration,inclusions of Al2O3 may occur partial decomposition 0.3-0.5V,0.5-0.7V inclusions can completely decompose Al2O3.Through SEM,it was observed that under the external voltage of 0.7V,the Fe-[70ppm Al] inclusions that had been generated were all decomposed.The energy required for Al2O3 decomposition includes the destruction of Al-O bond energy and the driving force energy to melt Al and O into molten steel,and the energy in the Fe-[70ppm Al] decomposition process is 169KJ/mol. |
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