Research On Erosion Behavior Of MgO-C Refractories In High Temperature Slag With Applied Voltage

With the improvement of molten steel cleanliness requirements,refractory becomes more and more important in steel production.A series of physical and chemical reactions among refractory,molten steel and slag will produce serious secondary pollution.In order to reduce the pollution of refractory on molten steel,this research applied the principle of molten oxide electrolysis?MOE?to study the most common refractory MgO-C brick in steel production.Using liquid slag as electrolyte and applying a reasonable voltage between MgO-C brick?cathode?and the molybdenum?anode?to research the effect of the applied voltage,temperature,reaction time and slag composition on the high temperature corrosion resistance of refractory.In general,the aim of this research is to explore the reasonable range of applied voltage in different slag composition,and to provide the relevant theory basis for the electrochemical protection of refractory.Conclusions are as follow:?1?Through the high temperature electrochemical workstation,it was found that the decomposition voltage of?SiO₂?in the slag?acidic and basic slag?was about 4.5V,and the decomposition voltage of?FeO?in oxidative slag was about 1.5V.On base of that,the reasonable range of applied voltage was confirmed.?2?It showed that applied voltage in the acidic,basic and oxidative slag made positive effect on the MgO-C brick.Through the SEM on the vertical penetration depth measuring of molten slag,it was found that the depth of slag penetration decreased with the increasing of applied voltage.?3?In the CaO-Al₂O₃-SiO₂ slag?acidic or basic?,when the applied voltage reached the decomposition voltage of?SiO₂?,the?SiO₂?of the cathode area would be reduced to Si.The precipitation of Si was the thermodynamic driving force of the precipitation of high melting point material.With the increasing of applied voltage,Ca₂SiO₄ would be precipitated near the MgO-C brick?cathode?to prevent the further reaction between molten slag and MgO-C brick.When the content of MgO increased,MA spinel would be precipitated at the cathode.It also protected MgO-C brick.?4?In the CaO-SiO₂-FeO oxidative slag,the applied voltage made?FeO?reduced preferentially at the cathode area to suppress?FeO?decarburizing on the MgO-C brick.When the applied voltage exceeded the voltage of Fe reduction,Ca₂SiO₄ would be precipitated.And then sediments would be formed on the surface of the refractory to protect MgO-C brick.The high-temperature slag electrodeposition method is expected to provide a new solution for protecting refractory from slag and molten steel.It is a new attempt in the production of high quality clean steel,and the relavant research is still being explored.