Effect of TiO2 Addition on the Melting Behaviors of CaO-SiO2-30%Al2O3-5%MgO System Refining Slags

To improve the yield of titanium alloy, a certain amount of TiO2 can be added to the refining slag system of Ti-bearing steel grades. With the aim of understanding the effect of TiO2 addition on the melting behaviors of CaO-SiO2-30%Al2O3-5%MgO refining slags, the melting points of the slags and the phases in the slags are herein studied at different temperatures in the laboratory. It is found that with the increase in TiO2 content (0 similar to 10%) in slag, the melting point of the slags drops first, and then rises. The effect of slag basicity (R = w(CaO)/w(SiO2), 2 similar to 10) shows a similar tendency. The TiO2 content and slag basicity evidently affect the precipitated phases in the slags at a lower temperature (e.g., 1310 degrees C). With the increase in basicity, the liquid areal fraction increases first, and then decreases. Moreover, the CaO-TiOx-Al2O3 phase (CTA) and its TiOx content show a declining trend at 1310 degrees C. When R = 10, large amounts of solid calcium aluminates are precipitated. With TiO2 addition in the slags, the TiOx contents in both liquid and CTA phases increase. Excessive TiO2 addition (e.g., 10%) leads to the large precipitation of CTA, as well. To improve the melting properties of the slag and the yield of Ti alloys during the refinement of Ti-bearing steel grades, a small TiO2 addition (e.g., 5%) may be considered.