Effect of FeO_t Content and CaO/SiO₂ Ratio on Hydrogen Dissolution in CaF₂–CaO–SiO₂‐Based Welding Fluxes

Abstract

The solubility of hydrogen in the CaF2–CaO–SiO2–FeOt slag system was studied to characterize the dependence of hydrogen dissolution behavior on the CaO/SiO2 ratio and the Fe3+/Fe2+ redox equilibrium at 1823 K. In an acidic slag composition, the dissolved hydrogen seems to exist as an incorporated hydroxyl, where the supplied water vapor reacts with the bridged oxygen (Oo) of the slag network. In a basic slag composition, hydrogen dissolves as a free hydroxyl in the molten slag by reacting with the free oxygen (O2−). Using FTIR (Fourier transform infrared) and Raman spectroscopy, the addition of FeOt depolymerized the slag structure in an acidic slag system, but polymerized the slag structure in a basic slag system as the FeOt content increased. Furthermore, the formation of γ‐ and δ‐FeO(OH) was controlled by the amount of Fe2O3 present in the flux and increased at higher concentrations of Fe2O3. At a fixed Fe2O3 content and with CaO/SiO2 ratios varying from 0.7 to 1.3, the hydrogen solubility curve was parabolic as a function of CaO/SiO2, with a minimum near the CaO/SiO2 ratio of 1.0 and rapidly increasing at CaO/SiO2 ratios above 1.0.

Analysis of Slag Chemistry by FTIR‐RAS and Raman Spectroscopy: Effect of Water Vapor Content in H2H2OCOCO2 Mixtures Relevant to a Novel Green Ironmaking Technology

“…With the ability to distort the dipole moment in a molecule, IR induces certain molecular vibrations (IR vibrational modes) that are characteristic of the chemical environment of the molecule (fingerprint). FTIR has been used to qualitatively determine the structure of silicate melts by many researchers . For qualitative/semiquantitaive determination of silicate species in the melt, a careful peak deconvolution should be done, vide infra.…”

“…FTIR has been used to qualitatively determine the structure of silicate melts by many researchers. [48,50] For qualitative/semiquantitaive determination of silicate species in the melt, a careful peak deconvolution should be done, vide infra. Infrared spectra were collected with a Continuum IR Microscope coupled to a Nicolet 6700 FTIR Spectrometer supplied by Thermo Scientific (Waltham, MA).…”

Study of the Structure of FeOx-CaO-SiO2-MgO and FeOx-CaO-SiO2-MgO-Cu2O-PdO Slags Relevant to Urban Ores Processing through Cu Smelting

“…In that research, it was revealed that the excess free energy of oxides in slag (CaO, MgO, MnO) is strongly dependent on the abundance of silicon anionic units, which was also elucidated further with ionization potential (Z/r 2 ) of the metal ions. In another study, Park et al [32] reported an increase of depolymerization of the CaF 2 -CaO-SiO 2 -FeO x slag system with increasing FeO x (0 to 21.5 wt.%). In this basic slag, FeO x acted as a polymerizing agent of the silicate slag.…”

Effect of Alumina and Extended Basicity on the Viscosity and Structure in the TiO2-MnO-Al2O3-8.64ZrO2-2.77Na2O Welding Flux System

“…Research has shown that light weight high strength steels such as high Mn containing AHSS steel (advanced high steel strength) are especially prone to defects during the welding process. According to Park et al, [1][2][3][4][5] dilution of the weld pool by the base plate, contamination of the weld pool by exogenous gases and particles, and the transfer of elements from slags are some of the issues observed during the welding process, which can exacerbate cracking in the weld zone. In particular, the viscous properties of the welding flux and its optimization ensure discrete separation of the metal from the slag, minimization of gas bubble entrainment, and improved spreading characteristics to inhibit atmospheric contamination.…”