Abstract：Due to the [Al] reaction with the CaO-SiO2-based mold flux used in the high-Al steels continuous casting processes, decreasing the SiO2 content is decreased and the Al2O3 content in mold flux is increased, thus converting the original CaO-SiO2-based mold flux into a CaO-SiO2-Al2O3-based mold flux. This conversion of the mold fluxes can cause the problem of high-Al steels continuous casting. Hence, study on the structural characteristics of the CaO-SiO2-Al2O3- based mold flux can provide fundamental data to design optimum fluxes for high Al-containing steels. In this paper, the structural characteristics of the CaO-SiO2-based and CaO-SiO2-Al2O3-based flux were studied by Raman spectroscopy. The results have shown that, the CaO-SiO2-based flux was the silicate structure whose main micro-structure units were Q0, Q1, Q2 and Q3. The network breakers prefer to depolymerize the silicate network in CaO-SiO2-Al2O3-based flux. While the CaO-SiO2-Al2O3-based flux with low SiO2 content, the [AlO4] tetrahedron was entered the silicate network and the melt converted into the aluminosilicates structure, the formation of Al-O-Al linkages and Si-O-Al linkages increased the degree of disorder of network. The results of Li2O replace Na2O and CaO replace MgO have shown that the ions will influence the formation of [AlO4] tetrahedron linkages. CaF2 replace CaO shown that the polymerization degree of mold slag decreased first, and then increased with the content of CaF2 more than 13 mol%. So, the influences of the ions type and the ions content on the structure were both need considered while designing the CaO-SiO2-Al2O3-based flux.
[1] Kim G H, Sohn I. Journal of Non-Crystalline Solids, 2012, 358: 1530. [2] Cho J W, Blazek K, Frazee M, et al. ISIJ International, 2013, 53(1): 62. [3] Lu Boxun, Chen Kun, Wang Wanlin, et al. Metallurgical and Materials Transactions B, 2014, 45: 1496. [4] Kim G H, Kim C S, Sohn I. ISIJ International, 2013, 53(1): 170. [5] Colomban P, Tournie A L, Ludovic B G. Journal of Raman Spectrometry, 2006, 37: 841. [6] WANG Xin, FAN Xian-guang, XU Ying-jie, et al(王 昕，范贤光，许英杰，等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2014, 34(8): 2117. [7] Shin S H, Cho J W, Kim S H. Journal of the American Ceramic Society, 2014, 97(10): 3263. [8] Hanao M, Kawamoto M, Watanabe T. ISIJ International, 2004, 44(5): 827. [9] McMillan P F. Journal of Non-Crystalline Solids, 1983, 55: 221. [10] Mysen B O, Virgo D, Seifert F A. American Mineralogist, 1985, 70: 88. [11] Mysen B O, Virgo D, Scarfe C M, et al. American Mineralogist, 1985, 70: 487. [12] Neuville D R, Cormier L, Massiot D. Chemical Geology, 2006, 229: 173. [13] Gao Jinxing, Wen Guanghua, Sun Qihao, et al. Metallurgical and Materials Transactions B, 2015, 46B: 1850. [14] Schulz T, Lychatz B, Haustein N, et al. Metallurgical and Materials Transactions B, 2013, 44B: 317. [15] Gao Jinxing, Wen Guanghua, Liu Qi, et al. Journal of Non-Crystalline Solids, 2015, 409: 8.
