Supersonically sprayed nanotextured surfaces with silver nanowires for enhanced pool boiling

Rapid production of nanoscale-textured surfaces for microscale devices is important for commercial applications. In this study, we introduce a commercially viable method to fabricate nanotextured surfaces used in pool-boiling heat-transfer applications. Silver nanowires were supersonically sprayed onto copper substrates with good adhesive strength. The coating method required little time and could be adapted for roll-to-roll processing. The fabricated nanotextured surfaces showed a significantly increased critical heat flux (CHF) and effective heat transfer coefficient (h_eff), as evidenced by the release of numerous bubbles from nanotextured nucleation sites during pool-boiling. The silver nanowires were well connected either by self-sintering or due to the fusion induced by supersonic impacts with the copper substrate. The thickness of the coated layer could be controlled by the number of spray sweeps/passes and the optimal thickness for maximizing CHF and h_eff was identified. The nanotextured surfaces were characterized by scanning electron microscopy and by bubble formation and release as visualized with a charge-coupled device camera.