|Cite this article as:|
|Dawei Cai, Li Zhang, Wanlin Wang, Lei Zhang, and Il Sohn, Dissolution of TiO2 and TiN inclusions in CaO-SiO2-B2O3 based fluorine-free mold flux, Int. J. Miner. Metall. Mater.,(2023). https://doi.org/10.1007/s12613-023-2622-9|
Mold flux serves a crucial metallurgical function of absorbing inclusions, which has a direct impact on the smooth of casting process and the casted slab quality. In this study, the dissolution behavior and mechanism of TiO2 and TiN inclusions in molten CaO-SiO2-B2O3 based fluorine-free mold flux were explored by in-situ Single Hot Thermocouple Technology combined with X-ray Photoelectron Spectroscopy. The results showed that the rutile TiO2 inclusion was effectively dissolved by the molten slag within 76 s, which the original [TiO6] octahedral structure was destroyed and converted to the network former [TiO4] tetrahedral. However, the dissolution rate of TiN inclusion was significantly lower than that of the TiO2 inclusion. This was primarily due to that, during the dissolution process of TiN inclusion, the TiN particle needed to be first oxidized and then dissolved in the molten slag into [TiO4] tetrahedral and [TiO6] octahedral structures, accompanied by the generation of a large amount of N2 gas. Besides, CaTiO3 crystals tended to nucleate and grow on the surface of the bubbles with sufficient [TiO6] octahedral and Ca2+ ions, resulting in the molten slag to be in a solid-liquid mixed state eventually.