Frosting and defrosting characteristics of multi-layer coated aluminum surfaces

Abstract

Delaying frost formation and shortening defrosting time were both of importance to enhance anti-frosting characteristics. To achieve those, functional multi-layers with a total thickness of <20 μm were successfully integrated over aluminum substrates by sequentially depositing a bottom electrical insulating layer, a middle heating layer, and a top superhydrophilic-superhydrophobic patterned layer. Frosting and defrosting characteristics of functional multi-layers were experimentally investigated. Coating functional multi-layers over aluminum substrates considerably enhanced anti-frosting characteristics. Specifically, the functional multi-layers effectively retarded frost formation on the surfaces, compared to superhydrophilic surfaces, while showing slightly higher frost formation than superhydrophobic surfaces. During defrosting, melting was completed in a fast manner due to the combined effects of the ultrafast temperature increase by the functional multi-layers and the excellent water drainage characteristics by the top superhydrophilic-superhydrophobic patterned layer.