FORMATION OF SPINEL IN MELT OF THE MgO-Al_2O_3-SiO_2-CaF_2 SYSTEM AGGLOMERATED WELDING FLUX AND ITS EFFECT ON VISCOSITY OF SLAG

摘要

X-ray examinations of structure of agglomerated flux of the MgO-Al_2O_3-SiO_2-CaF_2 system in solid and molten states evidence that in a temperature range above 1200℃ the Al_2MgO_4 hard spinel phase with a melting temperature of 2105℃ forms in the slag melt. It determines physical-chemical properties of the melt and, in particular, the smooth character of viscosity changes in a temperature range of 1180-1540℃. By manipulating proportions and concentrations of spinel-forming components Al_2O_3 and MgO, it is possible to achieve the optimal values of the temperature dependence of viscosity of the slag melt and, on this base, develop welding fluxes with predictable technological properties.