关键词: 冰晶形貌, 枝晶, 海藻晶, 表面能, 生长速率, 生长机制, 原位实验

Abstract: The icing phenomenon is ubiquitous in nature, from the formation of snowflakes to the low-temperature preservation of food to the anti-icing of aircraft wings. It is both a scientific and technological interest to understand and control the morphology of ice crystals. Inspired by the concept of mesoscience, this study raises the scientific hypothesis that surface energy plays an important role in the morphology evolution of ice crystals. To regulate the surface energy, different additives (sucrose, sodium chloride, and surfactant SDS) were added to the aqueous solution, and the icing processes with different surface tensions was observed by a homemade cooling device loaded at a laser confocal microscope. It was found that the morphologies of ice crystals transfer from dendritic with good symmetry to disordered seaweed crystals with the decrease of the surface tension at the same undercooling conditions, and this change was verified in different kinds of solutions. Further investigations showed that the lower surface tension of the solution resulted in a change of growth rate of ices in the solution. At high growth rates, the growing surface of ice crystals became unstable, and the crystal plane grew anisotropically, resulting in the formation of dendrite structures. However, at low growth rates, the growth surface of ice crystals was covered by additive molecules. The anisotropy of the crystal plane disappears, and hence a disordered dendrite structure was formed. The above findings confirmed the dominant role of supercooling and surface energy in the growth of the material structure, which provides experimental proof to evaluate the concept of mesoscience.

Key words: ice morphology, dendrite, seaweed crystal, surface energy, growth rate, growth mechanism, in-situ experiment