Substrate Dependence of the Freezing Dynamics of Supercooled Water Films: A High-Speed Optical Microscope Study

Abstract

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.

Pores Dominate Ice Nucleation on Feldspars

“…9,10 However, cryogenic temperatures can easily lead to situations where thermodynamic equilibrium is not reached, so that the results might not be transferable to ambient conditions. Studies on the interaction of water and ice with surfaces in ambient conditions have been restricted mainly to light microscopy 11 and spectroscopy 3 or scanning probe microscopy 12,13 . However, in the last two decades, advances in surface-sensitive techniques based 3 on electron spectroscopy 14 and microscopy 15 , that were traditionally limited to work in vacuum conditions, have allowed measurements at temperatures and pressures relevant to ice in ambient conditions.…”

“…Studies performed in cryogenic conditions at the molecular level clearly indicate that the interaction of water molecules with the surface determines the ice structure that will be formed at the interface. , However, cryogenic temperatures can easily lead to situations where thermodynamic equilibrium is not reached, so that the results might not be transferable to ambient conditions. Studies on the interaction of water and ice with surfaces in ambient conditions have been restricted mainly to light microscopy and spectroscopy or scanning probe microscopy. , However, in the last two decades, advances in surface-sensitive techniques based on electron spectroscopy and microscopy, that were traditionally limited to work in vacuum conditions, have allowed measurements at temperatures and pressures relevant to ice in ambient conditions. In this work, we take advantage of one of these techniques, environmental scanning electron microscopy (E-SEM), to study ice nucleation on feldspar surfaces.…”

Dynamics of Dendritic Ice Freezing in Confinement

“…Graph showing measured dendrite propagation speeds in mixed (red), glass (black), and insulating (blue) cells, with literature data for comparison: bulk propagation speeds from Shibkov et al (squares), growth speeds on single surfaces of plexiglass (plusses) and stainless steel (crosses) from Schremb et al, and glass from Pach et al (diamonds) …”

“…This body of theory applies to dendrites propagating through bulk water. However, experiments have also shown that very much greater values of v may be achieved at a given Δ T if the dendrite is allowed to instead grow along a thermally conductive external surface. − The effect is attributed to the fact that a dendrite adjacent to a conductive wall may shed its excess latent heat much more easily than may a dendrite in bulk water. Experiments have also shown that the presence of a thermally insulating wall offers no measurable speed increase …”

Studying Ice with Environmental Scanning Electron Microscopy

“…To understand how that happens, the molecular bases of the interaction of water molecules with surfaces need to be studied. Many different techniques can be used to study water interaction with surfaces and heterogeneous nucleation, such as photon spectroscopy [ 2 ], optical microscope [ 3 , 4 ], and others. Nevertheless, all these techniques lack the spatial resolution needed to study it at the required nanometer range.…”