| Abstract | Ice adhesion tests were conducted on five substrates with differing ice-phobic coatings. Rectangular-plate ice samples (25–62 cm2), freeze-bonded onto the surfaces, were pushed from one edge (at a nominal rate of 0.5 mm/s) until shear-detachment occurred. Freshwater and saline ice layers were investigated, where the intended test temperatures were -12 oC and -22 oC. For the freshwater ice cases it was found that spraying cold water onto the surfaces led to the formation of ice layers that never fully bonded/contacted the surfaces due to nonuniform freezing and lift-up/delamination. The mild bumpy texture of some of the surfaces and slight curvature of all of the substrates, where liquid could pool in ‘valleys’, contributed to this behavior. Hence, attempts to bond flat pre-shaped ice-plate specimens were unsuccessful. Furthermore, when spraying on smooth surfaces, ice-layer delamination occurred due to freezing of liquid and lift-up at the substrate edges. A thin layer (2–4 mm thickness) of saturated snow applied to the surfaces, however, did freeze and bond because it conformed to the non-flat features of the surfaces. Test results at -12 oC showed a wide variation of ice adhesive strength between the coatings (22–216 kPa). Degradation of the coatings with the number of tests was also noted (i.e. increasing adhesive strength), and was proportional to the adhesive strengths. At -22 oC the preparation method usually led to ice samples that were only partially bonded to the surfaces. In a few cases, video records enabled rough estimates of the contact areas so that approximate adhesive strengths were obtained. For saline ice generated by spraying at -12 oC and -22 oC, lift-off was not evident, however, no freeze-bonding occurred on any of the surfaces because a thin briny liquid layer was present at the interface. |
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