The formation and accretion of ice on high voltage (HV) power lines components represent a huge problem which can affect the efficiency of current conduction whose removal requires expensive and time-consuming treatments. Strong snowfalls can often involve severe drawbacks such as extended blackout and damages to the HV systems due to the accretion phenomena and the subsequent breakup of the lines. Superhydrophobic surfaces (SHSs) have been widely investigated for many applications but the correlation with icephobic performance has not been clearly highlighted yet, notwithstanding many recent papers on the subject (Liu et al, Nanomaterials 2016; Kim et al, ACS Nanoorg 2012).Water repellence depends on surface chemical composition and morphology. Coupling hierarchical micro-nanostructure with a very low surface energy, a stable Cassie-Baxter state is reached preventing water drops from wetting the surface. In this work, 50 cm-long aluminum conductors commonly used in HV lines were functionalized by dip coating into a ceramic oxide nanoparticles suspension, synthesized by sol-gel route, and chemically modified with fluoroalkylsilane (FAS) solution to obtain SHSs by the typical Lotus leaf approach. In addition, some more water-repellent conductors were fabricated by infusion in a fluorinated oil (Krytox 100), according to the so-called SLIPS approach. Both the design approaches provided materials with high dynamic performances (contact angle hysteresis < 10°), while the infused samples showed a static water contact angle of about 120°, much lower than 170° reached by SHS samples. However, the advantage of Krytox as outer layer lies in the greater homogeneity of the coating, with a decreasing of local defects, this circumstance being very relevant on local interaction between the liquid and the surface . As known from the literature, substrate roughness plays a key role in superhydrophobic properties, this parameter being linked with the icephobic behavior as well (Susoff et al, Applied Surface Science 2013; Fu et al, Applied Materials Interfaces 2014).To better understand the influence of roughness on nucleation and accretion of the ice, the functionalization was performed on smooth (Ra = 0,3 ?m) and sandblasted (Ra = 3.6 ?m) conductors, either by SHS or SLIPS approach. Treated samples were exposed outdoor during winter at the RSE test facility located in the west of Italian Alps, at an altitude of 959m asl. SHS conductors, under particular snowfall events and conditions, showed a significant delay (some hours) in snow deposition if compared to the untreated and SLIPS ones. This effect was noticed only on sandblasted samples, while smooth SHS conductors exhibited the same behavior of untreated and SLIPS surfaces, with an easy deposition and fast accretion of the snow layer during the atmospheric event.
Design and Fabrication of Superhydrophobic Coatings for High Voltage Power Lines Applications
Boveri Giulio;Mariarosa Raimondo;Veronesi Federico;
2017
Abstract
The formation and accretion of ice on high voltage (HV) power lines components represent a huge problem which can affect the efficiency of current conduction whose removal requires expensive and time-consuming treatments. Strong snowfalls can often involve severe drawbacks such as extended blackout and damages to the HV systems due to the accretion phenomena and the subsequent breakup of the lines. Superhydrophobic surfaces (SHSs) have been widely investigated for many applications but the correlation with icephobic performance has not been clearly highlighted yet, notwithstanding many recent papers on the subject (Liu et al, Nanomaterials 2016; Kim et al, ACS Nanoorg 2012).Water repellence depends on surface chemical composition and morphology. Coupling hierarchical micro-nanostructure with a very low surface energy, a stable Cassie-Baxter state is reached preventing water drops from wetting the surface. In this work, 50 cm-long aluminum conductors commonly used in HV lines were functionalized by dip coating into a ceramic oxide nanoparticles suspension, synthesized by sol-gel route, and chemically modified with fluoroalkylsilane (FAS) solution to obtain SHSs by the typical Lotus leaf approach. In addition, some more water-repellent conductors were fabricated by infusion in a fluorinated oil (Krytox 100), according to the so-called SLIPS approach. Both the design approaches provided materials with high dynamic performances (contact angle hysteresis < 10°), while the infused samples showed a static water contact angle of about 120°, much lower than 170° reached by SHS samples. However, the advantage of Krytox as outer layer lies in the greater homogeneity of the coating, with a decreasing of local defects, this circumstance being very relevant on local interaction between the liquid and the surface . As known from the literature, substrate roughness plays a key role in superhydrophobic properties, this parameter being linked with the icephobic behavior as well (Susoff et al, Applied Surface Science 2013; Fu et al, Applied Materials Interfaces 2014).To better understand the influence of roughness on nucleation and accretion of the ice, the functionalization was performed on smooth (Ra = 0,3 ?m) and sandblasted (Ra = 3.6 ?m) conductors, either by SHS or SLIPS approach. Treated samples were exposed outdoor during winter at the RSE test facility located in the west of Italian Alps, at an altitude of 959m asl. SHS conductors, under particular snowfall events and conditions, showed a significant delay (some hours) in snow deposition if compared to the untreated and SLIPS ones. This effect was noticed only on sandblasted samples, while smooth SHS conductors exhibited the same behavior of untreated and SLIPS surfaces, with an easy deposition and fast accretion of the snow layer during the atmospheric event.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
