Controlling the nucleation of ice is important in many areas including atmospheric sciences, cryopreservation, food  
science and infrastructure protection. Similarly, control and enhancement of nucleation of hydrates (crystalline  
structures containing a guest molecule in a cage of water molecules) impacts industrial applications related to carbon  
sequestration, methane transport and desalination. A particular challenge associated with artificial synthesis of  
hydrates in laboratory conditions involves the very long induction (wait) times, before hydrates nucleate.  
In this work, we show via experiments and analysis that a three-phase contact line of air, water, and an aluminum  
surface significantly promotes nucleation of both ice and carbon dioxide hydrates. Experiments are conducted in  
small bulk water systems with polished metal surfaces immersed in water. Experimental results show that metal  
surfaces induce faster heterogeneous nucleation of ice and carbon dioxide hydrates, primarily due to the  
hydrophilicity of water on metal surfaces. Furthermore, a completely immersed aluminum piece slows down  
nucleation compared to an aluminum piece which protrudes out from the bulk water resulting in the creation of the  
three-phase contact line of air, water and metal surface. Our results show that the nucleation temperature is lowered  
by a few degrees for ice, and the induction time is reduced for carbon dioxide hydrates in the presence of this three-  
phase contact line. Origin of nucleation at the three-phase contact is clearly observed.  
The present experiments are supplemented by a modeling effort which extends classical nucleation theory on a two-  
dimensional geometry. Our analysis shows that the air phase assists in faster heterogeneous nucleation on the metal  
surface. A seed-crystal of ice preferentially nucleates at the three-phase contact line where it gets assisted by both  
the air and the metal interfaces. Results show that the driving force for nucleation is increased if ice nucleates at the  
junction of two surfaces, and that this force depends on the angle at the three phase line. This driving force is higher  
for smaller angles and increased hydrophilicity of the two surfaces. Interestingly, our results also show that even  
when one surface is hydrophobic and the other hydrophilic, the driving force for nucleation is higher than  
heterogeneous nucleation on the hydrophilic surface alone. In summary, this analysis supports our experimental  
observations that nucleation preferentially originates at the three-phase contact line and is faster compared to the  
metal completely immersed inside water.  
Overall, the present experiments and modeling aid the understanding of nucleation of ice and carbon dioxide  
hydrates. These findings can also be generalized to crystallization phenomena across many different disciplines.


Faster Nucleation of Ice and Carbon Dioxide Hydrates at the Three-Phase Contact Line

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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