电渣重熔中TiO2对低氟CaF2-CaO-Al2O3-MgO-Li2O渣黏度和结构的影响

Effect of TiO2 on the Viscosity and Structure of Low-fluoride CaF2-CaO-Al2O3-MgO-Li2O Slag for Electroslag Remelting

摘要:

本文研究了连续冷却条件下电渣重熔中TiO₂对低氟CaF₂-CaO-Al₂O₃-MgO-Li₂O渣黏度的影响,并利用傅里叶变换红外光谱和拉曼光谱分析水淬渣和对应结构的关系。结果表明,渣的黏度随着TiO₂的增加而降低,当TiO₂含量达到13.1%,随着温度从1743K, 1793K, 1843K 增加至1893K时, 对应黏度从0.067 Pa?s, 0.059 Pa?s, 0.056 Pa?s 降低到0.054 Pa?s；当温度达到1843K或之上时,TiO₂的加入对降低黏度有较小的影响。随着TiO₂含量从0,4.3%,8.7%增加至13.1%,黏流活化能从58.0 kJ/mol,47.7 kJ/mol,42.8 kJ/mol降低到38.6 kJ/mol。此外,红外光谱结果表明,随着TiO₂的加入,渣中[AlOnF_4-n]-四面体络合物和[AlO₄]-四面体网状结构被解聚,但[AlO₆]-八面体结构没有发现；同时,拉曼光谱分析表明,TiO₂加入可解聚[AlO₄]-四面体网状结构中Al-O-Al键, 并且Q^₄单元转化为Q^₂单元,同时形成O-Ti-O和Ti-O-Ti键。这些结果都表明TiO₂可降低渣的聚合度,并且有利于渣的结构简单化。最终,黏度变化与渣的对应结构有很好的一致性。

Abstract:

The effect of TiO₂ on viscosity of low-fluoride CaF₂-CaO-Al₂O₃-MgO-Li₂O slag for electroslag remelting was investigated under the continuous cooling conditions and the FTIR and the Raman spectroscopy were employed to analyze the correction between the quenched slags and the corresponding structure in the study. It can be found that the slag viscosity lowers as gradually increasing TiO₂ content, and when TiO₂ content up to 13.1%, the corresponding viscosity values slowly decrease from 0.067 Pa?s, 0.059 Pa?s, 0.056 Pa?s to 0.054 Pa?s with the temperature increases from 1743 K, 1793 K, 1843 K to 1893 K and at higher temperature of 1843 K and above, TiO₂ addition has only a relatively small effect on lowering the slag viscosity. The calculated activation energy of viscous flow decreases from 58.0 kJ/mol, 47.7 kJ/mol, 42.8 kJ/mol to 38.6 kJ/mol as increasing TiO₂ content from 0, 4.3%, 8.7% to 13.1%. Additionally, the FTIR results reveal that with the addition of TiO₂, [AlO_nF_4-n]-tetrahedral complexes and [AlO₄]-tetrahedra network structures depolymerized, but [AlO₆]-octahedra is not found in the slag. Simultaneously, it can be seen by Raman analysis that with the addition of TiO₂, leading to the depolymerization of the Al-O-Al linkage in the [AlO₄]-tetrahedra network structures, the transformation of part Q^₄ units to Q^₂ units, and the forms of O-Ti-O and Ti-O-Ti chains. These results suggest that polymerization degree of these slags decreases as increasing TiO₂ content, which is beneficial to simplify slag structure. Finally, the changed slag structure is in good agreement with the slag corresponding to the varying viscosity.