Nano-textured surfaces using hybrid micro- and nano-materials for efficient water cooling

Water cooling heat transfer was enhanced by texturing the heated surface with various micro- and nano-materials. The increased surface area by texturing facilitated not only enhanced convection, but also turbulent mixing, which increased the effective heat-transfer coefficient. A heated copper substrate was textured with electroplated copper oxide, sprayed silver nanowire, or sprayed copper micro-particles. Sprayed micro-particles were subsequently nano-textured by sand blasting with kanthal (Mo₂Si) nanoparticles. Because of the extremely high hardness of kanthal, sand blasting dimpled the surface to increase the total surface area. Optimal texturing was identified for each material. Hybrid cases combining two different texturing materials were also investigated. All cases were quantitatively compared and that with the highest effective heat transfer was identified. Texturing materials were characterized by scanning electron microscopy and X-ray diffraction. The coating methods are simple, rapid, and scalable and may be cost-effective texturing schemes for various electronics cooling applications.