Characterization of B ₂ O ₃ ‐Modified CaF ₂ –CaO–Al ₂ O ₃ Slag for Improved Electroslag Remelting Processes: Electric Conductivity and Surface Tension

The electrical conductivity and surface tension of the CaF 2 –CaO–Al 2 O 3 –MgO slag with varying B 2 O 3 content (2–7 mass%) were measured between 1573 and 1823 K using the four‐electrode method and the maximum‐pull method. XPS analysis was conducted to investigate the effect of B 2 O 3 on the slag microstructure and its correlation with physical properties. Results indicated that the electrical conductivity of the slag exhibited a decreasing trend with an increase in B 2 O 3 content and a decrease in temperature. This reduction is attributed to a decrease in the content of highly conductive ions (F − and Ca 2+ ), and an increase in the degree of polymerization of the microstructure network, which hinders ion migration. Surface tension of the molten slag decreased with the increase of temperature and B 2 O 3 content. A rise in temperature enlarged the inter‐ionic distances and simultaneously disrupted the large‐sized ionic clusters present in the molten slag, thereby resulting in a reduction in the surface tension of the molten slag. The incorporation of B 2 O 3 also promoted the formation and polymerization of large‐sized structural units such as B–O–Al and [BO 4 ] 5− . This weakens the interaction forces between these units and the metal cations, thus reducing the slag surface tension.