Influences of different components on viscosities of CaO-MgO-Al2O3-SiO2 melts

Abstract

The present study is aim ed to distinguish the different influences o f CaO and MgO, as w ell as A 1,03 and SiO , on viscosity o f C a O -M gO -A ip.-SiO . melts. It is fo u n d that fo r melt without A l,0 3, viscosity increases m onotonously as CaO is gradually replaced by MgO. The addition o f A 1,03 leads to a complex variation o f viscosity. In different composition ranges, viscosity may exhibit different variation tendencies as changing the relative contents o f CaO and MgO while keeping contents o f other components constant. It is also fo u n d that when replacing SiO , by equivalent mole o f A l,0 3, (i) in CaO-A 1,0,-SiO, system, viscosity increases when A l,0 } content is sm all relative to CaO content (there are enough Car' ions to charge compensate A T 4 ions), but decreases when CaO content is inadequate fo r charge compensation; (ii) in MgO-Al,OsSiO , system, viscosity always decreases as substituting A l,0 3fo r SiO,. The reason fo r this difference fo r two systems may be resulted from the weak charge compensation ability o f Mg1 2* ion fo r Al3' ion relative to Ca2* ion. A ll the viscosity variations can be interpreted well by our new proposed viscosity model. Keywords: Viscosity; C aO -M gO -A l,03-S iO B r id g in g oxygen; Non-bridging oxygen