Effect of NaF and CaO/SiO2 on the hydrogen dissolution in the CaO-SiO2-FeOt based flux system

Abstract

The compositional effect of NaF and CaO/SiO2 on the hydrogen solubility in the NaF-CaO-SiO2-FeOt welding flux system at 1 823 K is presented. At a CaO/SiO2 of 1.3, higher NaF decreased the hydrogen solubility and at a CaO/SiO2 of 1.5, higher NaF had relatively little effect on the hydrogen solubility in the flux. The hydrogen solubility with CaO/SiO2 showed a parabolic behavior showing a minimum near unit basicity and increasing with higher basicity. FTIR (Fourier transform infra red) and Raman spectroscopy of asquenched flux samples showed the addition of NaF and higher CaO/SiO2 depolymerized the flux structure. At low and intermediate basicities from 0.9 to 1.3, higher NaF decreased the incorporated hydroxyl sites of Si(OH) and FeO(OH), which correlates well to lower hydrogen values. © 2013 ISIJ.