Role of Na2O and TiO2 on viscosity and structure of Sodium-Titanium-bearing slag

The viscosities of Na2O-TiO2-SiO2-CaO-MgO-Al2O3 slags were measured to enhance understanding of the effect of Na2O and TiO2 on the viscous behavior. An increase in the Na2O content lowered the viscosity but adding TiO2 increased the viscosity. The transformation of the structural units was investigated using in-situ temperature-dependent Raman spectra. TiO2 primarily existed in the slag system in the form of [TiO4]4− monomer, which acted as a network former. As Na2O increased, the chain structure (Q2, [Ti2O6]4− or [SiTiO6]4−) was broken by O2− ions to form tetrahedral monomer (Q0, [TiO4]4− or [SiO4]4−), which lowered the degree of polymerization. Adding TiO2, Q2 chain was formed by TiO2 and Q0 monomer to enhance the polymerization degree of the slag, resulting in the increase of the viscosity. Based on the Raman spectra and the hole theory, a quantitative relationship, lnη=3.7+0.88ln((Q2)/(Q0)2), between the structural units and viscosity of sodium- titanium-bearing slag was established.