Experimental Study On Wettability Of Al₂O₃-MgO-TiO₂ Non-Metallic Inclusions And Molten Steel

In the steel metallurgy process,deoxidation and inclusion control are important for improving the quality of steel products.Al₂O₃-MgO-TiO₂ composite inclusions are easily formed when Al-Mg-Ti and other composite deoxidizers are used for deoxidation.In refining and rolling process of some steel grades,the inclusions such as Al₂O₃ and Al₂O₃-MgO in steel are also easily transformed into Al₂O₃-MgO-TiO₂ composite inclusions under certain conditions.The properties between these non-metallic inclusions and molten steel,especially the wettability,have an important influence on the floatation,removal,aggregation and distribution of inclusions.Therefore,it is particularly important to analyze and study the wettability between Al₂O₃-MgO-TiO₂ composite inclusions formed in molten steel and molten steel.In this paper,the contact angle between molten steel and Al₂O₃-MgO-TiO₂composite inclusions at high temperature is studied,and the influence of wettability on the movement behavior of inclusions in molten steel is systematically analyzed.The contact angles between Al₂O₃-MgO,Al₂O₃-TiO₂ and Al₂O₃-MgO-TiO₂ inclusions and molten steel at different temperatures and holding time were measured by seat drop method.The results show that the contact angle between molten steel and inclusion substrates decreases with the increase of temperature.Under the condition of 1600?,the contact angle tends to be stable with the further increase of temperature.The contact angle between molten steel and inclusion substrates decreases with the increase of holding time at 1600?.When holding time reaches about 180s,the contact angle will not change any more.Under the condition of holding for 3 minutes at 1600?,the influence of inclusion types on contact angle is more obvious.The contact angle of Al₂O₃-MgO inclusions decreases rapidly first and then increases gradually with the increase of MgO content in the substrate.The contact angle of Al₂O₃-TiO₂ and Al₂O₃-MgO-TiO₂ inclusions decreases gradually with the increase of the content of titanium dioxide in the substrate.Because of the similarity between the simulated particles and the inclusions,the inclusions of Al₂O₃·TiO₂,Al₂O₃·MgO,MgO and Al₂O₃ were simulated by EVA,polyethylene,polypropylene and EBS particles respectively.A simulation system was established with the similarity ratio of 1:2.5.The effect of wettability on the movement behavior of Al₂O₃-MgO-TiO₂ inclusion particles with different composition in molten steel was studied by means of high-speed camera.The results show that the wettability between EBS particles and water is the worst and the removal rate of EBS particles is higher when the simulated inclusions particles are removed by floating.In the process of particle floating,at low Reynolds number,the wettability of inclusion simulated particles and deionized water is worse,and the uniform floating velocity is higher.At high Reynolds number,the actual uniform floating velocity of different inclusion simulated particles fluctuates within-10%¹0%compared with the theoretical calculated value,indicating the wettability has little effect on the uniform floating velocity of inclusions.The wettability of EVA simulated particles and water is the best,and the mixing time is the shortest,which makes it easier for the more uniform distribution of EVA simulated particles in molten steel.