Rheological Properties and Structures of CaO–Al2O3–La2O3–B2O3 Slags with Various B2O3 Contents
Rheological Properties and Structures of CaO–Al2O3–La2O3–B2O3 Slags with Various B2O3 Contents
复制标题
不同B2O3含量的CaO·Al2O3·La2O3·B2O3渣的流变性能和结构
DOI：
10.1007/s40831-022-00525-9
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发表时间：
2022
影响因子：
2.4
通讯作者：
Maofa Jiang
中科院分区：
文献类型：
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作者：
Lei Fan;Jie Qi;Chengjun Liu;Maofa Jiang
针对传统CaO-SiO_2-Na_2O-CaF_2系保护渣在连铸含La FeCrAl合金过程中存在严重的钢渣反应和氟污染问题，设计了低活性环保型CaO-Al_2O_3-La_2O_3-B_2O_3渣系，并对不同B_2O_3含量的渣系进行了流变性研究。结果表明，随着B2O3wt%从0增加到15wt%，渣的粘度和活化能逐渐降低。结构分析表明，B3+主要以平面[BO_3]-三角结构形式存在。随着B_2O_3含量的增加，[BO_3]单元通过破坏aliv-O-AlIV键进入初始的铝酸盐网络结构，形成更多的aliv-O-BIII和B-O-B键，从而导致桥氧的增加和渣结构的聚合。由于[BO_3]单元的层状结构，层间B-O键的分子引力较弱，降低了炉渣的整体结构强度，从而导致粘度降低。随着B_2O_3的加入，断裂温度总体上逐渐降低。CaAl_2O_4的析出量随着B_2O_3含量的增加而减少，这是由于高聚合度的[AlO_4]-四面体结构减少所致。在本研究中，Ca~(2+)由于其较小的阳离子场强而起到电荷补偿作用，而La~(3+)主要与NBO相互作用以平衡电荷。
Aiming at the problem of severe steel-flux reaction and fluorine pollution occurred in the process of continuous casting La-bearing FeCrAl alloy with conventional CaO–SiO2–Na2O–CaF2-based mold fluxes, the low-reactive and environmentally friendly CaO–Al2O3–La2O3–B2O3slag system was designed, and rheological behavior of the slags with different B2O3contents was studied. Results showed that with the increase of B2O3from 0 to 15 wt%, the slag viscosity and activation energy decreased gradually. Structural analysis indicated that B3+mainly existed in the form of planar [BO3]-triangular structure with the addition of B2O3. With increasing B2O3contents, [BO3] units entered into the initial aluminate network structure via destroying AlIV–O–AlIVlinkages to form more AlIV–O–BIIIand B–O–B linkages, resulting in the increase of bridging oxygen and the polymerization of slag structure. Due to the layered structure of [BO3] units, the molecular attraction of B–O bonds between the layers was weak, which reduced the overall slag structural strength, thus, leading to the decrease of viscosity. The break temperature decreased gradually on the whole with the addition of B2O3. The precipitated amount of CaAl2O4reduced with increasing B2O3content, which resulted from the decrease of high-polymerized [AlO4]-tetrahedral structure. In this study, Ca2+played the charge compensation effect owning to its small cationic field strength, while La3+mainly interacted with NBOs for balancing charges.Graphical Abstract