Enhanced capillary performance of copper wicks with honeycomb-forest micro-nano composite structures by inhibitor-regulated electrodeposition

High-efficient wicking structure with strong capillarity is desired to improve the thermal performance of heat pipes. Electrodeposition presents great potential on fabricating wicks with superior capillary performance. However, conventional electrodeposited wicks are mainly disordered and chaotic, making it difficult to balance capillary pressure and permeability. In response, this study proposed a novel wick with a biomimetic Honeycomb-Forest Composite Structure (HFCS). It was fabricated via regulated electrodeposition and compared with conventional Disordered-Forest Structure (DFS). The effects of the current density and PEG inhibitor concentration on the morphology, wettability, and capillary rise performance were investigated. The HFCS exhibited significantly improved wettability and capillary performance compared to the DFS: the time required for a droplet to spread completely over the surface decreased from 0.286 s to 0.088 s, and the capillary performance parameter (K/R eff ) increased by 123%. The inhibitor further enhances the capillary performance of HFCS. The K/R eff was improved by an additional 40%, reaching 1.46 μm, which is significantly higher than the range reported in the literature (0.29-1.05 μm). The enhancement mechanism is that the dual-scale pores of the HFCS regulate the local permeability to achieve a balance between capillary pressure and permeability. Therefore, the biomimetic HFCS is an efficient capillary-transport structure.