A facile approach for fabrication of superhydrophilic, hydrophilic and hydrophobic surface for improved surface properties

Surface wettability plays an important role in the thermal management of high-heat flux-generating microelectronic devices. In the present study, three surfaces with different wettability characteristics have been developed using a two-step electrodeposition method. The superhydrophilic surface is prepared by anodizing the copper surface, while the hydrophilic and hydrophobic surfaces are prepared by a hybrid nanocomposite coating of Cu-TiO2 and Cu-MWCNTs, respectively. The effect of electrodeposition parameters on surface characteristics is investigated. Further, the combined effect of porosity and wettability has been analyzed for the nucleate pool boiling heat transfer characteristics as part of the application. The high current density for a short duration in the first stage of electrodeposition led to the development of a highly porous but fragile layer, which is stabilized by providing low current density for a long time in the second stage. The evolution of hydrogen bubbles during the electrodeposition process created an enormous number of cavities, which enhanced the porosity, surface roughness, and active nucleation site density compared to the plane copper surface. An insignificant evolution of hydrogen bubbles in the second step resulted in strong adhesive bonding among the pores and between the deposit layer and substrate surface. An increase in current density increases the coating thickness and surface roughness, consequently making the hydrophilic surface even more hydrophilic. The maximum heat transfer coefficient, and critical heat flux are obtained for superhydrophilVic and hydrophilic surfaces, respectively, while the earliest onset of nucleation is observed on a hydrophobic surface.