THE ADHESION OF ICE TO HYDROPHOBIC SURFACES.
NAVAL RESEARCH LAB WASHINGTON D C
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Determinations were made on the adhesional shear strength of ice formed against clean, highly polished steel, against close-packed monolayers adsorbed on steel, and against thin coatings of organic polymers painted on metal surfaces. The adsorbed monolayers reduced the shear strength by about one third of that for ice against clean steel. The values of the shear strength for the different monolayers were approximately the same despite a wide difference in the chemical constitution of the adsorbates. The monolayers also had the effect of changing the character of the breaks from clearly cohesional, ductile fractures from clean steel to apparently adhesional, brittle fractures from the monolayers. On lightly abraded steel the results were quite different from those on the highly polished surfaces - the adhesion was noticeably higher and the breaks were cohesional for both clean and monolayer-coated abraded surfaces. The shear strength against the organic coatings ranged from values equal to that of ice against clean steel to values 70 to 80 lower. These results showed no simple correlation with the water contact angle on the organic coatings. The appearance of the ice separated from the various substrates was examined by forming plastic replicas against the ice surface. These replicating solutions etched the ice to reveal crystal structure and crystal lattice defects. The etching features showed the ice lattice to be highly defective near the substrate. Author
- Snow, Ice and Permafrost