Heat transfer through mould flux with titanium oxide additions

The effects of titanium pick-up on the heat transfer and solidification nature of mould flux, when casting titanium stabilised stainless steels, were investigated. To achieve this, the overall thermal resistance of a typical industrial mould flux was measured by means of a specially designed experimental apparatus that could simulate the casting process. The procedure was then repeated with TiO₂ doped mould fluxes. A lower TiO₂ content (<5%) in the test flux primarily resulted in the formation of cuspidine (Ca₄Si₂O₇F₂) upon solidification, while higher titanium levels promoted the formation of perovskite (CaO·TiO₂) at the expense of cuspidine. The effect of titanium pick-up on heat transfer is largely overshadowed by the formation of a thermal contact resistance on the mould wall during flux solidification.