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The electrochemical behavior of graphite in KF-AlF 3 -based melt with a cryolite ratio ͑molar ratio of KF to AlF 3 ͒ of 1.3 as well as a low oxygen content at 750°C was investigated by cyclic voltammetry, potentiostatic electrolysis, sampled-current voltammetry, and chronopotentiometry. Aluminum deposited on graphite at a potential of ca. 0.25 V ͑vs Al͒ and the electrochemical intercalation of potassium into graphite occurred at ca. Ϫ0.1 V ͑vs Al͒. The intercalation of potassium into graphite enhanced the formation of Al 4 C 3 . The deposition of aluminum on graphite was a linear diffusion-controlled process, while its reverse reaction involved kinetic limitations. Sampled-current voltammetry results indicated that the aluminum deposition on graphite was depressed in the potential region extending from about 0.1 to 0.03 V ͑vs Al͒. Chronopotentiometry results revealed that the critical cathodic current density for potassium intercalation was about 400 mA cm −2 .

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Heat exchangers are general equipment for energy exchange in the industrial field. Enhancing the heat transfer of a heat exchanger with low pump energy consumption is beneficial to the maximum utilization of energy. The optimization design for enhanced heat transfer structure is an effective method to improve the heat transfer coefficient. Present research shows that the biomimetic structures applied in different equipment could enhance heat transfer and reduce flow resistance significantly. Firstly, six biomimetic structures including the fractal-tree-like structure, conical column structure, hybrid wetting structure, scale structure, concave-convex structure and superhydrophobic micro-nano structure were summarized in this paper. The biomimetic structure characteristics and heat transfer enhancement and drag reduction mechanisms were analyzed. Secondly, four processing methods including photolithography, nanoimprinting, femtosecond laser processing and 3D printing were introduced as the reference of biomimetic structure machining. Finally, according to the systemic summary of the research review, the prospect of biomimetic heat transfer structure optimization was proposed.

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