Investigation of Alumina Wetting by Fe-Ti, Fe-P and Fe-Ti-P Alloys

The wetting of alumina substrates by Fe-Ti, Fe-P and Fe-Ti-P alloys has been investigated using sessile drop experiments conducted under an inert gas atmosphere in the temperature range of 1550 to 1620 degrees C. The surface and interfacial structures have been explored by scanning electron microscopy and energy dispersive X-ray spectroscopy. Substantial additions of titanium are known to induce steel melts to wet alumina due to the formation of a Ti-rich reaction product at the alloy/ceramic interface, but the present work has shown that even low Ti concentrations can induce a reactive wetting process leading to an improvement of the wettability of alumina by Fe alloys. The contact angle of molten steel containing phosphorus on alumina decreased with increasing P content. The improvement of the wetting behaviour in this system was attributed solely to the adsorption of P onto the surface of the Fe melt. The addition of P as a ternary alloying element to the system Fe-Ti proved to be beneficial to the wetting behaviour. The measured contact angles were much lower than those in the binary systems Fe-Ti and Fe-P. This effect was related to the fact that P enhances the activity of Ti in the Fe melt. According to experimental observations, it turns out that the wettability of liquid Fe-based alloys, when an Al2O3 surface is present, is not only a property of the metal/oxide couple but is also dependent on the oxygen partial pressure, whereas temperature variations bring about a comparatively small effect. This work is of interest in understanding the phenomena pertaining to inclusion engineering and steel-refractory interactions, such as the clogging of submerged entry nozzles by agglomerated alumina particles during the continuous casting process. (C) Koninklijke Brill NV, Leiden, 2012