Ice adhesion tests are widely used to assess the performance of potential icephobic surfaces and coatings. A great variety of test designs have been developed and used over the past decades due to the lack of formal standards for these types of tests. In many cases, the aim of the research was not only to determine ice adhesion values, but also to understand the key surface properties correlated to low ice adhesion surfaces. Data from different measurement techniques had low correspondence between the results: Values varied by orders of magnitude and showed different relative relationships to one another. This study sought to provide a broad comparison of ice adhesion testing approaches by conducting different ice adhesion tests with identical test surfaces. A total of 15 test facilities participated in this round-robin study, and the results of 13 partners are summarized in this paper. For the test series, ice types (impact and static) as well as test parameters were harmonized to minimize the deviations between the test setups. Our findings are presented in this paper, and the ice- and test-specific results are discussed. This study can improve our understanding of test results and support the standardization process for ice adhesion strength measurements.

A simple process to obtain a slippery surface with anti-ice and ice-phobic properties has been developed and characterized in laboratory. The coating is realized by growing a nanostructured pseudo-boehmite on an aluminum substrate and applying an environmentally compatible final functionalization consisting of a fluorine-free oligomeric short-chain alkylfunctional silane. The resulting surface is conceptually similar to a slippery liquid infused porous surface (SLIP) material, but the porous infrastructure is inorganic and the process to generate it is very simple, rapid and economic. The coating performance in terms of hydrophobicity at room and low temperatures, ice nucleation temperature and ice adhesion forces were assessed in laboratory. Moreover, hydrophobicity persistence was tested after prolonged immersion in acid, basic and saline solutions while the durability of ice-phobic behavior was assessed by repeated shear stress tests. Results are compared with those of a superhydrophobic hierarchical aluminum surface obtained with a fluorinated siloxane. The novel coating shows very good anti-ice properties and relevant durability, with some differences from the fluorinated surface. The novel slippery coating process is promising for industrial applications, also taking into account its environmental compatibility, simplicity and low cost.

Overhead power line conductors and ground wires are affected by ice and snow accretion which can easily adhere to their surface, causing the breakage of cables and the collapse of pylons due to excessive weight. In Italy, the main concern is about wet snow: this phenomenon occurs close to zero degrees Celsius with snow density reaching up to 350 Kg/m³. Anti-icing and anti-snow coatings represent a possible strategy to mitigate ice accretion on overhead power line structures. Many works are oriented to achieve anti-icing properties, starting from superhydrophobic coatings or slippery coatings; however, there is a lack of knowledge about the anti-snow behaviour of these surfaces. In this work, aluminium alloy conductor and ground-wire samples were prepared with different coatings, which include hydrophobic, superhydrophobic and slippery surfaces prepared in the laboratory. Characterisations of sample wettability at room and low temperatures and ice adhesion strength were carried out in the laboratory. Anti-snow behaviour was studied in outdoor test facilities in the Italian Alps during several snowfall events. Furthermore, the environmental parameters were also recorded. Two figures of merit were developed to quantify anti-snow behaviour of the samples: one describing the fraction of surfaces covered by snow during the snowfall event and the other representing the maximum accretion load reached on the samples. Results of laboratory and field testing are compared and discussed. Field testing evidenced a promising snowphobic behaviour for all the samples, despite the different anti-icing and wettability properties measured in the laboratory. The mitigation of the phenomenon was found to occur mainly with two different mechanisms: the delay in snow accretion on the surface and/or the early shedding of the snow-sleeve.

Several hydrophobic and superhydrophobic aluminum surfaces were prepared with a three-step process that includes chemical etching, a treatment in hot water and a further coating with fluoroalkysiloxane (FAS). By varying the concentration of the etchant, the immersion time in the etchant and the boiling time, surfaces characterized by different roughness were obtained, with a wettability ranging from hydrophobic to superhydrophobic values. The icephobic properties were tested and the results reveal important differences among the samples, related to the roughness of the surface and the etching and boiling treatment processes.