Study on the adhesion mechanism of Al2O3 inclusions on Al2O3-C refractory in Al-killed steel
The nozzle clogging during continuous casting process of Al-killed steel is a difficult problem.It is very important to make clear the formation mechanism of the nozzle clogging to solve the problem.In this study,molten steel containing a single type of Al2O3 inclusions was prepared firstly in laboratory,then a Al2O3-C refractory rod was dipped into it and reacted for different times to study the adhesion behavior of Al2O3 inclusions on the refractory rod.Based on the experimental results,the formation mechanism of nozzle clogging during continuous casting of Al-killed steel was explored.It was found that after a period of time,two layers of Al2O3 were gradually formed on the surface of the refractory rod from inside to outside.The first layer was dense and smooth with smaller thickness,and the second layer was loose and rough with larger thickness.The formation mechanism of nozzle clogging was explored as follows,after the refractory rod was dipped into molten steel for a certain time,the SiO2,Al2O3 and C in the surface area of refractory reacted and SiO,Al2O gases was generated due to the rise of temperature.Then the gases diffused to the liquid steel,and reacted with Al in steel and SiO2 in refractory respectively at the interface between the refractory and steel to generate Al2O3.At the same time,SiO2 on the surface of the refractory rod would also react with Al in molten steel to form Al2O3.After the first Al,O3 layer was formed,the Al2O3 inclusions in liquid steel were easily attached to it,then the second layer of loose Al2O3 was formed.With the extension of time,the Al2O3 layer became thicker,and the nozzle clogging was developed gradually.The formation of the first Al2O3 layer was due to chemical reaction and grew slowly;the second Al2O3 layer was mainly due to the adhesion of inclusions in steel on the first layer and grew faster.
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