Elucidating Electrical Conductive Mechanisms for CaF2-SiO2-Al2O3-MgO Welding Fluxes in Liquid and Crystalline States

H Yuan and ZJ Wang and YY Zhang and ZS Li and C Wang, METALLURGICAL AND MATERIALS TRANSACTIONS B-PROCESS METALLURGY AND MATERIALS PROCESSING SCIENCE, 55, 5068-5079 (2024).

DOI: 10.1007/s11663-024-03309-6

Electrical conductivity of flux, particularly in a liquid state, plays significant roles in optimizing arc and molten pool behaviors pertinent to submerged arc welding. However, the effects of crystallization on flux electrical conductivity remain less clear. Here, the relationship between electrical conductivity of CaF2-SiO2-Al2O3-MgO fluxes with varying Al2O3/MgO ratios between 0.51 and 4.13 and crystallization characteristics have been established. It is demonstrated that, as a function of Al2O3/MgO ratio, liquid-state flux conductivity gradually decreases from 0.115 to 0.078 S/cm. Such results can be attributed to the reduced carrier number and impaired carrier diffusion. Furthermore, flux crystallization ability diminishes and then enhances as the Al2O3/MgO ratio increases in the range from 0.51 to 4.13. Crystals gradually shift from Mg-dominating phases to spinel, and ultimately to Al-dominating phases. When the Al2O3/MgO ratio is 0.51, coarse Mg- dominated crystals strongly inhibit conductivity. However, when the Al2O3/MgO ratio ranges from 0.97 to 1.85, scattered spinel phases showcase a minor impact on conductivity as the effective carrier number remains almost constant. This study sheds light on flux crystallization behaviors and also contributes to optimized flux design for desired electron transport capabilities.

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