Study On Slag Resistance Of Resin-bond Unburnt MgO-CaO System And Low-carbon MgO-C System Refractory

In this article, induction furnace-slag-resistance test was used to study the attack of the AOD slags(CaO-SiO2 slags)and refining slags(CaO-Al2O3 slags) on specimens of various unburnt MgO-CaO contents and low-carbon MgO-C contents. Four kinds of slags were used in this work. Among low-carbon MgO-C refractories, effect of a-AUOs powder and MgAlON powder and Siaty additives on corrosion resistance of samples by slags has been carried out. In terms of MgO-CaO refractories, we have conducted the study on corrosion resistance and penetration resistance of MgO-CaO refractories with various CaO contents (10% 20% 30%) and a-AfeOs powder and MgAlON powder additives by slags. Based on the properties of MgO-CaO refractories, slag corrosion and its penetration, dissolution rate of refractories in slags, according to the liquid zone and the saturation surface at 1600 癈 of CaO-SiO2-Al2O3-MgO quarternary system, having calculated slag viscosity and saturated concentration of MgO and CaO at boundary between refractory and slag as well, the author discussed and analyzed slags attack upon the MgO-CaO system refractories. Suggestion may be made of the improvements upon the service life of the linings either by controlling the composition of slags or by selecting properly the constituents of MgO-CaO refractories. The mechanism of slag attack on MgO-CaO refractories has been suggested basing on the experimental results, microscopic observation, and electron microprobe analysis. The conclusions drawn from the study results are as follows:(1) In terms of low-carbon MgO-C refractory, a-AkOs powder and MgAlON powder in matrix have improved performances of erosion resistance and penetration resistance of samples noticeably;(2) MgO-CaO refractories with the higher CaO content are more suitable to withstand the attack of CaO-SiOi slags, while it is the other way round in terms of CaO-Al2O3 slags;(3) MgO-CaO refractories with the higher CaO content are more suitable to withstand the penetration of any kind of slag;(4) It is found that MgO-CaO refractories containing MgAlON powder in matrix have the most excellent performance of slag corrosion resistance. Its corrosive depth is 18%-25% lower than that of imported burnt MgO-CaO brick;(5 ) Main corrosion mode of MgO-CaO refractories by molten CaO-SiOa- MgO -A^Oa slag and metal is the corrosion at slag-metal interface. Concentration gradient of CaO SiO2 Al2O3 MgO along the slag-metal interface causes the interfacial tension gradient and results in Marangony convection. The Marangony convection accelerates the mass transfer of dissolved component from specimen. It results in the occurrence of corrosion. In addition, the interfacial tension and viscosity of slag also have significant influence on penetration resistance of MgO-CaO system refractory.