Crystallization Behavior of Calcium Silicate-Based Mold Flux Under Electropulsing Treatment with Different Pulse Duty Cycles

Electropulsing treatment (EPT), as an external field technology, has the potential to adjust the crystallization of mold flux when it is locally applied in the casting mold. In this study, the effect of EPT with different pulse duty cycles on crystallization behavior of calcium silicate-based mold flux was investigated. The results show that the morphology of crystals precipitated in the mold flux transforms from elongated grains into block-like grains, with the average grain radius increasing from 14.1 ± 1.01 μm to 24.7 ± 2.07 μm when the duty cycle increases from 10% to 70%. Phase analyses show that the fraction of Ca 2 Mg 0.75 Al 0.5 Si 1.75 O 7 in the mold flux increases from 11.2 wt.% to 14.7 wt.%, while that of Ca 4 Si 2 O 7 F 2 decreases from 88.8 wt.% to 85.3 wt.% with the increase of the duty cycle. The variation of content of these phases is mainly due to their electrical conductivity, which leads to the enhancement of melilite and the inhibition of cuspidine precipitation when the electropulsing is applied.