Browsing by Subject "hydrophobic surfaces"

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    PRINTING HYDROPHOBIC STAINLESS STEEL GRAPHENE COMPOSITES
    (University of Texas at Austin, 2023) O'Donnell, M.; Budan, J.; McGuire, J.; Jalagam, P.; Kulkarni, Achyuth; Ansell, T.Y.
    Hydrophobic surfaces have low surface energies, which prevents water droplets from wetting the surface. Metals typically have high surface energies leading to highly wettable, hydrophilic behavior. Nano-structuring metallic surfaces could be a way of making a metallic surface hydrophobic potentially leading to improved corrosion resistance, drag reduction, etc. 3Dprinting a metal matrix nanocomposite maybe a scalable method to fabricate hydrophobic metals. Graphene nanoplatelets (GNP) were mixed with 316L stainless-steel (SS) powder and printed on a selective laser melting platform. The composite samples included 0, 1, 2, and 3 vol% GNP. Initial printing jobs ran into some issues that were addressed by adding a vibration source and aluminum foil to the inside of the powder hopper. Additionally, energy density was set higher than 60 J/mm3 to avoid lack of fusion issues. Printing of small and large plates of composite samples was performed at energy densities starting from 60 J/mm3 going up to 100 J/mm3 . As-printed composite sample surfaces consistently exhibited hydrophobic behavior with contact angles exceeding 90°. After polishing, the surfaces exhibited hydrophilic behavior. What is compelling; however, is that while contact angles for pure SS was as expected, i.e., angles < 80°, the composite samples showed angles between 80° and 90°, drawing closer to 90° with an increase in GNP.