The effects of RE (rare earth)
oxide on
viscosity of
mold fluxes were investigated with a rotary viscometer. The results show that: (1) The viscosity of mold fluxes is remarkably
increased by
RE oxide addition, especially when the mass fraction of RE oxide is more than 10%. (2) By addition of RE oxide, precipitation of the insoluble particles with high melting point from the molten slag with the decreasing of the temperature leads to the increase of viscosity. Viscosity curve shows that RE oxide can be solubilizied certainly in mold fluxes. When RE oxide is in a state of supersaturation, the existence of insoluble particles also makes the viscosity of mold fluxes to increase. (3) Not only the viscosity of mold fluxes can be reduced, but also the capacity to dissolve and absorb RE oxide can be increased by Li_2O, B_2O_3 and BaO. However, the contents of Li_2O, B_2O_3, and BaO should be controlled to suitable levels. (4) The
solidification temperature of mold fluxes can be increased by the addition of RE oxide, which is unfavorable to heat transfer and lubrication of mold fluxes between steel shell and mold.