Effect of B₂O₃ Addition on Electrical Conductivity and Structural Roles of CaO-SiO₂-B₂O₃ Slag

The effect of B₂O₃ addition on electrical conductivity of CaO-SiO₂-B₂O₃ slag was investigated using the four-electrode method. The slag structure was determined from Raman and nuclear magnetic resonance spectra. The experimental results show that the electrical conductivity, as the B₂O₃ content in the slag increased from 0 to 10 pct, monotonously increases from 0.0769 to 0.2642 Ω⁻¹ cm⁻¹ at temperatures ranging from 1783 to 1873 K (1510 °C to 1600 °C). The effects of temperature on electrical conductivity obeyed the Arrhenius law, and the electrical conductivity increased as the temperature increased. The Raman spectra results indicated that addition of B₂O₃ led to an increase of Q³(Si) at the cost of Q²(Si), which will increase the degree of polymerization of the slag. ¹¹B nuclear magnetic resonance spectra showed that both BO₃ trigonal and BO₄ tetrahedral structures increased with the increasing B₂O₃ content. There was a competitive effect between the presence of these structures and an enhanced degree of polymerization of slags in the networks, which resulted in the increased electrical conductivity of the slag. A structure–electrical conductivity model for CaO-SiO₂-B₂O₃ slag was established.