Pach E, Rodriguez L, Verdaguer A
Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain.
Institut de Ciència de Materials de Barcelona ICMAB-CSIC, Campus de la UAB, E-08193 Bellaterra, Spain.
J Phys Chem B. 2018 Jan 18;122(2):818-826. doi: 10.1021/acs.jpcb.7b06933. Epub 2017 Oct 4.
The freezing of supercooled water films on different substrates was investigated using a high-speed camera coupled to an optical microscope, obtaining details of the freezing process not described in the literature before. We observed the two well known freezing stages (fast dendritic growth and slow freezing of the water liquid left after the dendritic growth), but we separated the process into different phenomena that were studied separately: two-dimensional dendrite growth on the substrate interface, vertical dendrite growth, formation and evolution of ice domains, trapping of air bubbles and freezing of the water film surface. We found all of these processes to be dependent on both the supercooling temperature and the substrate used. Ice dendrite (or ice front) growth during the first stage was found to be dependent on thermal properties of the substrate but could not be unequivocally related to them. Finally, for low supercooling, a direct relationship was observed between the morphology of the dendrites formed in the first stage, which depends on the substrate, and the roughness and the shape of the surface of the ice, when freezing of the film was completed. This opens the possibility of using surfaces and coatings to control ice morphology beyond anti-icing properties.
利用与光学显微镜相连的高速摄像机，对过冷水膜在不同基底上的冻结过程进行了研究，获得了此前文献中未描述的冻结过程细节。我们观察到了两个众所周知的冻结阶段（快速枝晶生长以及枝晶生长后剩余水液体的缓慢冻结），但我们将该过程细分为不同的现象并分别进行研究：基底界面上的二维枝晶生长、垂直枝晶生长、冰域的形成与演化、气泡捕获以及水膜表面的冻结。我们发现所有这些过程均取决于过冷温度和所使用的基底。在第一阶段，冰枝晶（或冰前沿）的生长取决于基底的热性能，但无法明确地将其与热性能联系起来。最后，对于低过冷度情况，在薄膜冻结完成时，观察到了第一阶段形成的枝晶形态（取决于基底）与冰表面粗糙度和形状之间的直接关系。这为利用表面和涂层来控制冰的形态开辟了可能性，而不仅仅局限于防冰性能。
