Long Xiao, Long Shaolei, Luo Wenbo, Li Xiang, Tu Changping, Na Yunhao, Xu Jinxin
School of Materials and Energy Engineering, Guizhou Institute of Technology, Guiyang 550003, China.
Materials (Basel). 2023 Feb 25;16(5):1903. doi: 10.3390/ma16051903.
In this study, solidified films of CaO-AlO-BaO-CaF-LiO-based mold fluxes with different contents of AlO addition were acquired by immersing an improved water-cooled copper probe in bulk molten slags. This probe can obtain films with representative structures. Different slag temperatures and probe immersion times were employed to investigate the crystallization process. The crystals in the solidified films were identified using X-ray diffraction, the morphologies of the crystals were observed using optical microscopy and scanning electron microscopy, and the kinetic conditions, especially the activation energy of devitrified crystallization in glassy slags, were calculated and discussed based on the differential scanning calorimetry. The results indicated that after adding extra AlO, the growing speed and thickness of the solidified films increased, and more time was required for the film thickness to reach a steady state. In addition, fine spinel (MgAlO) precipitated in the films at the early stage of solidification after adding 10 wt% of extra AlO. Together with LiAlO, spinel (MgAlO) acted as nuclei for the precipitation of BaAlO. The apparent activation energy of initial devitrified crystallization decreased from 314.16 KJ/mol (original slag) to 297.32 KJ/mol (5 wt% AlO added) and 269.46 KJ/mol (10 wt% AlO added). The crystallization ratio of the films also increased after adding extra AlO.
在本研究中，通过将改进的水冷铜探头浸入大量熔渣中，获得了添加不同含量AlO的CaO-AlO-BaO-CaF-LiO基保护渣凝固膜。该探头能够获得具有代表性结构的薄膜。采用不同的熔渣温度和探头浸入时间来研究结晶过程。利用X射线衍射对凝固膜中的晶体进行鉴定，通过光学显微镜和扫描电子显微镜观察晶体的形貌，并基于差示扫描量热法计算和讨论动力学条件，特别是玻璃态熔渣中非晶晶化的活化能。结果表明，添加额外的AlO后，凝固膜的生长速度和厚度增加，且膜厚达到稳态需要更多时间。此外，添加10 wt%额外AlO后，在凝固初期薄膜中析出了细小的尖晶石（MgAlO）。尖晶石（MgAlO）与LiAlO一起，作为BaAlO析出的晶核。初始非晶晶化的表观活化能从314.16 KJ/mol（原始熔渣）降至297.32 KJ/mol（添加5 wt% AlO）和269.46 KJ/mol（添加10 wt% AlO）。添加额外的AlO后，薄膜的结晶率也有所提高。
