中国物理B ›› 2021, Vol. 30 ›› Issue (2): 28103-0.doi: 10.1088/1674-1056/abc168

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  • 收稿日期:2020-08-26 修回日期:2020-09-09 接受日期:2020-10-15 出版日期:2021-01-18 发布日期:2021-01-26

Effects of heat transfer in a growing particle layer on microstructural evolution during solidification of colloidal suspensions

Jia-Xue You(游家学)1,†, Yun-Han Zhang(张运涵)2, Zhi-Jun Wang(王志军)2, Jin-Cheng Wang(王锦程)2, and Sheng-Zhong Liu(刘生忠)1   

  1. 1 Key Laboratory of Applied Surface and Colloid Chemistry, Ministry of Education; Shaanxi Key Laboratory for Advanced Energy Devices; Shaanxi Engineering Laboratory for Advanced Energy Technology; Institute for Advanced Energy Materials; School of Materials Science and Engineering, Shaanxi Normal University, Xi'an 710119, China; 2 State Key Laboratory of Solidification Processing, School of Materials Science and Engineering, Northwestern Polytechnical University, Xi'an 710072, China
  • Received:2020-08-26 Revised:2020-09-09 Accepted:2020-10-15 Online:2021-01-18 Published:2021-01-26
  • Contact: Corresponding author. E-mail: jiaxueyou@snnu.edu.cn
  • Supported by:
    Project supported by the National Key Research and Development Program of China (Grant Nos. 2018YFB1106003, 2017YFA0204800, and 2016YFA0202403), the National Natural Science Foundation of China (Grant No. 51901190), the China Postdoctoral Science Foundation (Grant No. 2020M673336), and the Peak Experience Program (2018) of Northwestern Polytechnical University, China.

Abstract: Heat transfer is the foundation of freezing colloidal suspensions and a key factor for the interface movement. However, how the thermal conductivity of particles affects freezing microstructural evolution remains unknown. Here in this work, a mathematical model is built up to investigate thermal interactions among a growing particle layer, pulling speeds, and the freezing interface under a thermal gradient. Experiments are conducted to confirm the tendency predictions of the model. With the increase of pulling speeds, the drifting distance of the freezing interface increases and the time to finish drifting decreases. When the thermal conductivity of particles (k p) is smaller than that of the surrounding (k w), the freezing interface tends to go forward to the warm side. Contrarily, the freezing interface tends to go back to the cold side when the thermal conductivity of particles is larger than that of the surrounding (α =k p/k w >1). It originates from the shape of the local freezing interface: convex (α <1) or concave (α >1). These morphological changes in the local interface modify the premelting drag force F f. When α <1, F f decreases and the freezing morphology tends to be the frozen fringe. When α >1, F f increases and the freezing morphologies tend to be ice spears. These understandings of how the thermal conductivity of particles affect microstructural evolution may optimize the production of freeze-casting materials and their structural-functional properties.

Key words: solidification, colloidal suspensions, heat transfer, microstructural evolution

中图分类号:  (Solidification)

  • 81.30.Fb
82.70.Dd (Colloids) 02.60.Cb (Numerical simulation; solution of equations) 47.20.Hw (Morphological instability; phase changes)