Wetting and corrosion characteristics of thermally sprayed copper-graphene nanoplatelet coatings for enhanced dropwise condensation application

Abstract

Water vapour condensation is frequently used as an effective means of transferring heat using dropwise condensation on non-wetting surfaces. The rate of heat transfer can be enhanced with dropwise condensation on non-wetting hydrophobic and superhydrophobic surfaces when compared to filmwise condensation on a wetting surface. Since low surface energy materials are mostly polymeric with low durability and poor thermal conductivity, copper-graphene nanoplatelet (Cu-GNP) composite coatings are developed in this work using atmospheric plasma spray (APS) and high-velocity oxy-fuel (HVOF) as versatile and scalable surface engineering techniques. It is demonstrated that by adjusting the deposition parameters, it is possible to preserve the GNPs in the coating structure. After treating with a stearic acid solution, the coatings demonstrate superhydrophobicity and extreme water repelling behavior with a water contact angle of 164° and sliding angle of 1° Raman analysis confirmed the presence of GNP in the coating with minimal defects. It is shown that the HVOF Cu-GNP coating developed in this work can improve the corrosion resistance up to 89% when compared to the uncoated Cu surface. This coating can potentially promote dropwise condensation while offering enhanced corrosion stability.

Keywords

• Graphene nanoplatelet (GNP)
• Atmospheric plasma spray (APS)
• High velocity oxygen-fuel (HVOF)
• Superhydrophobicity
• Dropwise condensation
• Corrosion resistance