Etching-enabled ultra-scalable micro and nanosculpturing of metal surfaces for enhanced thermal performance

Abstract

Incorporation of micro- and nanostructures on metals can improve thermal performance in a variety of applications. In this work, we demonstrate two independent highly scalable and cost-effective methods to generate micro- and nanostructures on copper and stainless steel, two widely used metals in energy and thermal applications. The performance of the developed structures, fabricated using scalable chemical etching techniques, is compared against their respective base metals. Our results demonstrate significant flow boiling heat transfer coefficient improvements up to 89% for etched copper and 104% for etched stainless steel. Mercury porosimetry is used to demonstrate that the varying pore-size distributions and presence of micro/nanoscale channels help to regulate heat transfer mechanisms, such as nucleate and convective flow boiling. Furthermore, structure integrity after 7-day flow boiling tests demonstrate surface structure resiliency to damage, a key challenge to implementation. This work combines advances in thermal performance with surface structure durability to provide guidelines for broader application of similar chemical etching methods to scalably create micro- and nanosculptured surfaces.