Experimental investigation into radiative heat transfer characteristics for mould fluxes containing transition oxides

Abstract

Infrared transmittance of glassy and crystalline mould fluxes was measured using a Fourier transform infrared spectrometer at room temperature. Radiation heat transfer from the steel shell to the mould was calculated by a model. The results indicate that transition metal oxides MnO, FeO and TiO₂ have a marked negative effect on infrared transmittance and radiation heat flux of glassy samples. With MnO, FeO and TiO₂ added, the reductions of radiation heat flux in glassy samples are 19–25%, 34–36%, 6–29% respectively. X-ray diffraction results indicated that the crystalline phase in transition oxides free samples was mainly Ca₄Si₂O₇F₂. After transition oxides MnO, FeO and TiO₂ added, Mn₂SiO₄, Fe₂SiO₄, CaTiO₃, Ca₂SiO₄ and other minor phases were also precipitated in mould fluxes. On account of strong refraction and scattering, the negative effect on radiation heat flux in crystalline samples was much larger than that in the glassy ones.