Superhydrophilic catenoidal aluminum micropost evaporator wicks

Abstract

We introduce the superhydrophilic catenoidal aluminum (Al) wicks fabricated by a multi-step wet etching process followed by wet chemical oxidation. The unique three-dimensional sidewall morphology of the developed wick provides the re-pinning of the liquid meniscus during the receding, which substantially increases the thin evaporative film area and the resulting heat transfer performance. The nanostructured aluminum oxide layer (AlO(OH)) was incorporated to enhance both the corrosion resistance as well as the wettability of the wick with water. The experiment shows that the heat transfer coefficient of the developed wick rapidly increases as the heat flux increases up to ~60 W/cm2. The maximum heat transfer coefficient of the catenoidal wick is measured to be ~117% higher than that of the previously-reported cylindrical ones. The numerical simulation clarifies that the increase in the heat transfer coefficient was due to the ~75% increase in the thin evaporative film area. The polarization scanning test shows that the corrosion resistance of the superhydrophilic catenoidal wicks was increased by ~82% compared to the unstructured ones, which clarifies the incorporated aluminum oxide layer acts as an effective corrosion barrier. This work introduces the Al evaporator wicks with substantially improved heat transfer as well as anti-corrosion performances, which will help develop ultra-light, high-performance heat spreaders.