Development of Hydrophobic and Hydrophilic Surfaces for Pool Boiling Applications via Electric Discharge Coating Technique

Electric Discharge Coating (EDC) has been a key technique in altering surfaces for industrial and biomedical purposes, yielding robust, corrosion-resistant surfaces with controlled roughness. Recognizing these benefits, the focus of recent efforts has been on developing surfaces optimized for pool boiling heat transfer applications. Utilizing EDC, four surface types were created, employing various microparticle and dielectric medium combinations. Two sets of micro-composite surfaces—Ti-Cu and Zn-Cu—were crafted using hydrocarbon (HC) oil as the dielectric medium, while another pair used deionized (DI) water. To ensure consistency for comparison, the EDC process parameters were standardized. Assessment of the surfaces included examining surface roughness, porosity, and wettability. Elemental analysis highlighted carbide and oxide depositions on HC oil and DI water-developed surfaces, respectively. Notably, HC oil-derived surfaces exhibited hydrophobic traits, while those from DI water were hydrophilic. Surface morphology displayed discrete pores, acting as nucleation sites for bubbles, thereby enhancing boiling performance. Porosity levels ranged from 39.6 to 48.6%, with surface roughness spanning 1.48 μm to 1.87 μm. Comparing the pool boiling outcomes among the same micro-composite-coated surfaces unveiled superior performance in the hydrophilic variants. Within the micro-composite types, the Zn-Cu coated surfaces displayed the most efficient boiling heat transfer.