Absorption behavior of TiO2 inclusions by different high titanium steel mold slags
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摘要: 为了提高高钛钢连铸过程中保护渣吸收夹杂物的速率，设计了五种潜在的高钛钢保护渣，将原位观察试验和旋转圆柱法相结合，分别观察和定量分析了各保护渣对TiO2夹杂物的吸收行为及吸收速率的差异，采用扫描电镜-能谱仪（SEM-EDS）对TiO2试样与保护渣接触的界面进行分析，以确定TiO2在保护渣中的溶解机理。结果表明，TiO2在CaO-SiO2-BaO渣中溶解速率最快，其次为低碱度CaO-SiO2渣，两种渣在原位试验中耗时较短，且完全溶解，在旋转圆柱试验中溶解速率分别为0.285 、0.281 mm/min。TiO2在高碱度CaO-SiO2、CaO-SiO2-Al2O3和CaO-SiO2-Al2O3-BaO渣系中溶解速率较慢，仅CSAB渣完全溶解，旋转圆柱试验中溶解速率分别为0.151、0.101 mm/min和0.191 mm/min。阻碍TiO2溶解的主要原因是溶解的TiO2与渣中CaO反应生成的高熔点CaTiO3使得保护渣局部粘度和熔点上升。Abstract: To enhance the inclusion absorption rate of mold slags during continuous casting of high-titanium steel, five candidate high-Ti steel slags were designed. The absorption behaviors and absorption rate differences of TiO2 inclusions by each slag were investigated through a combination of in-situ observation tests and rotating cylinder method with quantitative analysis. SEM-EDS was employed to analyze the interface between TiO2 samples and slags, elucidating the dissolution mechanism of TiO2 in the slag. Results demonstrate that TiO2 dissolution rate was fastest in the CaO-SiO2-BaO slag, followed by the low-basicity CaO-SiO2 slag. Both achieved complete dissolution with shorter durations during the in-situ tests, exhibiting dissolution rates of 0.285 mm/min and 0.281 mm/min respectively in the rotating cylinder tests. Comparatively, TiO2 dissolution rates decreased significantly in the high-basicity CaO-SiO2, CaO-SiO2-Al2O3, and CaO-SiO2-Al2O3-BaO systems, with only the CSAB slag completely dissolving (0.151, 0.101 mm/min, and 0.191 mm/min respectively). The primary inhibition mechanism was identified as the formation of high-melting-point CaTiO3 through reaction between dissolved TiO2 and CaO in the slag, which elevated local viscosity and melting point of the slags.
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图 3 保护渣吸收TiO2的试验装置示意
Figure 3. Schematic diagram of apparatus for dissolution of TiO2 in the slags
图 4 不同保护渣对TiO2样品的吸收过程
Figure 4. Absorption process of TiO2 by different slags
（a）LCS；（b）HCS；（c）CSB；（d）CSA；（e）CSAB
图 5 溶解前与溶解后的TiO2试样形貌
Figure 5. Morphology of TiO2 sample before and after dissolution
(a)溶解前；(b)溶解后
图 6 旋转柱试验后各保护渣溶中TiO2含量
Figure 6. Content of TiO2 in slags after the rotating cylinder experiment
图 7 不同保护渣与TiO2试样界面处的线扫描
Figure 7. The line scanning results at the interface of different slags and TiO2 sample
（a）LCS；（b）HCS；（c）CSB；（d）CSA；（e）CSAB
表 1 设计的保护渣的化学组分
Table 1. Designed chemical compositions of mold slags
No. SiO2 CaO MgO Al2O3 Na2O CaF2 BaO LCS 43 26 3 6 8 10 4 HCS 32 37 3 6 8 10 4 CSB 32 21 3 6 8 10 20 CSA 18 37 3 20 8 10 4 CSAB 18 21 3 20 8 10 20 
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表 2 TiO2在不同保护渣中溶解所用的时间
Table 2. The dissolution time of TiO2 in different slags
No. Dissolution time/s Completely dissolved LCS 100 Yes HCS 390 No CSB 116 Yes CSA 391 No CSAB 400 No
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