Herein, the effects of BaO (i.e. 5, 10, 15 and 20 pct) on the viscosity and structures of a new fluorine-free CaO-Al2O3-TiO2-based mold flux with w(CaO pct)/w(Al2O3 pct) ratio of 1.0 are investigated using a rotary viscometer, molecular dynamics (MD) simulations, and Raman spectroscopy. The viscosity of the samples (the testing temperature is 1300 °C) decrease from 0.46 to 0.21 Pa·s as the BaO content increased from 5 to 20 pct, and the activation energy decreases from 150.7 to 119.7 kJ·mol−1, the break temperature (Tbr) decreases from 1475 K to 1429 K which are achieved as the initial testing temperature of 1300 °C decreased under the furnace cooling. With the addition of BaO, the MD simulation results suggest that the coordination numbers (CNs) of Al (Ti)-O are reduced, while Q3, Q4, and Q5 are depolymerized into Q0, Q1, and Q2. The Raman spectroscopy results illustrate that the bridge oxygens (BOs) originating from the Ti-O-Ti (Al) linkages and Q2 (Al-O−) are depolymerized into Q1 (Si-O−) and Q0 (Al-O−) as the BaO content is increased. The Raman spectroscopy results agree well with those of the MD simulation. Therefore, BaO can simplify the structure of melts and decrease the viscosity of such systems. This work not only presents a new fluorine-free CaO-Al2O3-TiO2-based mold flux, but also deepens the understandings of the role of BaO in this system.

中文翻译：

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BaO对新型高钛钢无氟CaO-Al2O3-TiO2基助熔剂粘度和结构的影响

在此，BaO（即 5、10、15 和 20 pct）对具有 w(CaO pct)/w(Al2O3 pct) 比率的新型无氟 CaO-Al2O3-TiO2 基保护渣的粘度和结构的影响使用旋转粘度计、分子动力学 (MD) 模拟和拉曼光谱对 1.0 进行了研究。随着 BaO 含量从 5 pct 增加到 20 pct，样品的粘度（测试温度为 1300 ℃）从 0.46 Pa·s 降低到 0.21 Pa·s，活化能从 150.7 降低到 119.7 kJ·mol-1，断裂温度 (Tbr) 从 1475 K 降低到 1429 K，这是在炉冷却下初始测试温度 1300 °C 降低时实现的。随着 BaO 的加入，MD 模拟结果表明 Al (Ti)-O 的配位数 (CN) 减少，而 Q3、Q4 和 Q5 解聚为 Q0、Q1 和 Q2。拉曼光谱结果表明源自 Ti-O-Ti (Al) 键和 Q2 (Al-O-) 的桥氧 (BO) 被解聚为 Q1 (Si-O-) 和 Q0 (Al-O-)随着 BaO 含量的增加。拉曼光谱结果与 MD 模拟结果非常吻合。因此，BaO 可以简化熔体的结构并降低此类体系的粘度。这项工作不仅提出了一种新的无氟 CaO-Al2O3-TiO2 基保护渣，而且加深了对 BaO 在该体系中作用的理解。BaO 可以简化熔体的结构并降低此类体系的粘度。这项工作不仅提出了一种新的无氟 CaO-Al2O3-TiO2 基保护渣，而且加深了对 BaO 在该体系中作用的理解。BaO 可以简化熔体的结构并降低此类体系的粘度。这项工作不仅提出了一种新的无氟 CaO-Al2O3-TiO2 基保护渣，而且加深了对 BaO 在该体系中作用的理解。