Localized electrodeposition micro additive manufacturing of pure copper microstructures

The fabrication of pure copper microstructures with submicron resolution has found a host of applications,such as 5G communications and highly sensitive detection.The tiny and complex features of these structures can enhance device performance during high-frequency operation.However,manufacturing pure copper microstructures remain challenging.In this paper,we present localized electrochemical deposition micro additive manufacturing(LECD-μAM).This method combines localized electrochemical deposition(LECD)and closed-loop control of atomic force servo technology,which can effectively print helical springs and hollow tubes.We further demonstrate an overall model based on pulsed microfluidics from a hollow cantilever LECD process and closed-loop control of an atomic force servo.The printing state of the micro-helical springs can be assessed by simultaneously detecting the Z-axis displacement and the deflection of the atomic force probe cantilever.The results showed that it took 361 s to print a helical spring with a wire length of 320.11μm at a deposition rate of 0.887μm s^(-1),which can be changed on the fly by simply tuning the extrusion pressure and the applied voltage.Moreover,the in situ nanoindenter was used to measure the compressive mechanical properties of the helical spring.The shear modulus of the helical spring material was about 60.8 GPa,much higher than that of bulk copper(~44.2 GPa).Additionally,the microscopic morphology and chemical composition of the spring were characterized.These results delineate a new way of fabricating terahertz transmitter components and micro-helical antennas with LECD-μAM technology.

Novel Hollow Re-entrant Structures Improving Hydrophobicity of Metal Surfaces

Re-entrant structures have drawn increasing attention because of their hydrophobicity.However,it is very difficult to manufacture re-entrant structures at the micron scale on metal surfaces.In this study,we designed and manufactured novel hollow re-entrant structures employing laser ablation and electrodeposition technology.This designed hollow re-entrant structure on metal surfaces has been fabricated successfully,which has high processing efficiency and good repeatability.The morphology and size of the hollow re-entrant structures were characterized.We found that the hydrophobic performance of hollow re-entrant structures was improved after being in the atmosphere for 3 days.After electrodeposition,the static contact angle was 133°.However,after being placed in the atmosphere for 3 days,the static contact angle was 140.4°,which is 5.2%higher than that after electrochemical deposition.We explained the cause of this phenomenon.The change of element content on the surface of hollow re-entrant structures was used to indicate the formation of metal oxide.After being in the atmosphere for 3 days,oxygen content increased by 0.4%.The metal surfaces with hollow re-entrant structures have a broader application prospect.

Recent progress in bio-inspired macrostructure array materials with special wettability—from surface engineering to functional applications

Bio-inspired macrostructure array(MAA,size:submillimeter to millimeter scale)materials with special wettability(MAAMs-SW)have attracted significant research attention due to their outstanding performance in many applications,including oil repellency,liquid/droplet manipulation,anti-icing,heat transfer,water collection,and oil–water separation.In this review,we focus on recent developments in the theory,design,fabrication,and application of bio-inspired MAAMs-SW.We first review the history of the basic theory of special wettability and discuss representative structures and corresponding functions of some biological surfaces,thus setting the stage for the design and fabrication of bio-inspired MAAMs-SW.We then summarize the fabrication methods of special wetting MAAs in terms of three categories:additive manufacturing,subtractive manufacturing,and formative manufacturing,as well as their diverse functional applications,providing insights into the development of these MAAMs-SW.Finally,the challenges and directions of future research on bio-inspired MAAMs-SW are briefy addressed.Worldwide efforts,progress,and breakthroughs from surface engineering to functional applications elaborated herein will promote the practical application of bio-inspired MAAMs-SW.

Research Progress on Corrosion Resistance of Magnesium Alloys with Bio-inspired Water-repellent Properties:A Review

Thanks to its excellent mechanical properties,magnesium alloys have many potential applications in the aerospace and other fields.However,failure to adequately solve corrosion problems of magnesium alloy becomes one of the factors restricting its wide use in many industrial fields.Inspired by nature,researchers designed and fabricated bio-inspired water-repellent(superhydrophobic and slippery liquid-infused porous surface)surfaces with special wetting properties by exploring the surface microstructures of plants and animals such as lotus leaf and nepenthes pitcher,exhibiting excellent corrosion-resistant performance.This article summarizes the research progress on corrosion resistance of magnesium alloys with bio-inspired water-repellent properties in recent years.It mainly introduces the corrosion reasons,types of corrosion of magnesium alloys,and the preparation of magnesium alloys with bio-inspired water-repellent properties to improve corrosion resistance.In particular,it is widely used and effective to construct water-repellent and anti-corrosion coating on the surface of magnesium alloy by surface treatment.It is hoped that the research in this review can broaden the application range of magnesium alloys and provide a powerful reference for the future research on corrosion resistance of magnesium alloys.