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High-quality micro-holes play an important role in modern industry. However, in micro-hole drilling, a series of problems, such as chip removal and heat dissipation, restrict the improvement of micro-hole processing quality. Ultrasonic-assisted drilling (UAD) is a hybrid machining technology that combines conventional drilling (CD) with ultrasonic-assisted machining and it has great advantages when processing regular-size holes. This study mainly focuses on the influence of vibration amplitude in UAD on micro-holes manufacturing. By analyzing the cutting mode caused by periodic vibration in UAD, the influence of amplitude on the contact characteristics of the cutting edge and workpiece was studied regarding chip formation and separation ratio. Finite element simulations and experiments of micro-hole manufacturing using UAD and CD are conducted. The results show that the chip damage in UAD is more severe than CD, and as the amplitude increases, the chips became more fragmented. Compared with CD, in UAD, the thrust force is reduced by 20.1–30.05%. In addition, in UAD, the tool wear is better suppressed than in CD, and the increase in the amplitude ensures the integrity of the cutting edge. In CD, the morphology of the inner wall of the micro-hole is observed, indicating that the surface tearing and material loss are serious. In contrast, in UAD, as the amplitude increases, the material loss is almost completely suppressed. Consequently, the ultrasonic-assisted micro-hole drilling technology can be an optimal method to overcome the urgent problem of high-quality micro-hole manufacturing.

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.

Slippery liquid-infused surfaces (SLISs) are developed as a potential alternative to superhydrophobic surfaces (SHSs) to resolve the issues of poor durability in corrosion protection and wear resistance. In this work, we used a simple laser processing technology to prepare a SLIS on the aluminum alloy (7075) surface. The superhydrophobicities of the modified surface and the oil film formed by liquid injection make the corrosive medium difficult to directly contact the surface and thus have a significant effect on corrosion resistance. The water and oil repellent SLIS exhibits durable corrosion resistance and excellent tribological properties compared with the SHS. The anticorrosion and wear resistance performances provided by the composite film have been assessed by multiple methods including the electrochemical test, immersion test, and friction wear test. The results indicate that compared to the bare surface, laser-ablated surface (LAS), and fluoroalkyl silane-modified SHS, the SLIS composite coating has better corrosion resistance and wear resistance, which is of great significance to expand the potential applications of 7075 aluminum alloys. The work provides a research basis for expanding the practical application of SLISs in complex environments.

The slippery liquid infused porous surface has developed into a potential technology to solve the problem of poor durability in corrosion resistance. Herein, a kind of slippery liquid infused porous surface is created on 7075 aluminum alloy by wire electrical discharge machining for corrosion resistant applications. The hardness of the constructed porous microstructure is similar to the aluminum alloy substrate material, which ensures the stability of the slippery liquid infused porous surface. The modification of low surface energy substance fluorosilane avoids the direct contact between corrosive liquid and porous surface, and improves the lyophobic performance of the porous microstructure surface. The corrosion resistance of the porous microstructure surface is enhanced by the injection of perfluorinated lubricating oil. The experimental results show that the created slippery liquid infused porous surface can display super-slippery properties and durable corrosion resistance. The average sliding velocity of a water droplet is 0.48 ± 0.05 mm s−1 at a sliding angle of 5°. The corrosion current density of the surface is 3.116 × 10−6 A cm−2, which is 2 orders of magnitude lower than that of the polished surface. And the impedance radius reaches 90 kΩ cm2, which is about 20 times that of the polished surface.

Design and fabrication of smart materials with reversible wettability for oil-water separation have attracted worldwide attention due to the increasingly serious water pollution problem. In this study, a rough oxide coating with micro/nanoscale structures is developed on the 304 stainless steel mesh (SSM) by laser ablation. The smart surface with ethanol immersion and natural drying treatments shows the wetting conversion between underwater superoleophobicity and superhydrophobicity. Based on the wettability transition behavior, both light and heavy oil-water mixtures can be separated with the high separation efficiency. Moreover, after being exposed to various corrosive solutions and high temperatures, the smart surface still shows prominent environmental stability. Switchable surface with excellent properties should be an optimal choice to solve the environmental conditions that need to be addressed urgently.

An experimental study was conducted on laser-assisted machining of β21s titanium alloy to investigate the effects of input variables of laser-assisted micromachining (LAMM) and conventional micromachining (CM) on the surface quality of β21s titanium alloy. At the same time, the tool wear patterns of LAMM and CM were revealed, and the wear law of the tools under different laser parameters when cutting different distances was studied as well. The experimental results showed that an optimum roughness value of 0.132 μm was obtained at a laser power of 30 W, a cutting speed of 100 mm/s, and a cutting depth of 10 μm, reduced by 61.7% as compared to CM. On the other hand, during the LAMM and CM experiments, the flank wear of the tools was characterized by bonding wear, while the degree of tool wear was effectively reduced in LAMM. Meanwhile, the influence of cutting length and laser power on tool wear is obtained under the condition of constant cutting speed and cutting depth. In addition, in the process of LAMM, as the cutting length increases and other processing parameters remain unchanged, the optimal laser power is not constant. Increasing the laser power appropriately can effectively suppress tool wear.

Presented in 1996, maskless localized electrochemical deposition (LECD) is an emerging and unconventional manufacturing technology that originated from precision electroforming and electroplating. As a novel additive manufacturing technology, it forms a three-dimensional structure layer by layer at atomic scale. In this work, we present a review of the theoretical basis and key parameters of maskless LECD technology. LECD process, almost limited to linear structure-based depositions, is capable of creating structures with high aspect ratio up to 280. However, the degree of deposition accuracy is not satisfactory during the whole process. Besides, the deposition rate is rather slow and the highest deposition rate of 25 μm/s was reported in published literature. Moreover, not all metals can be deposited due to the limitations of the electrochemical discipline. For instance, the effects of interelectrode potential difference, interelectrode gap, scanning speed, electrolyte concentration, and energy field on the quality of maskless LECD were discussed. Although all parameters abovementioned have an effect on the deposition results, there is currently no optimization software that can calculate the optimal values in an effective manner. By combining different deposition structures, special tiny part systems can be generated or integrated into devices for tackling current and future challenges in some fields such as electronic circuits, microfluidics, communications, and biomedical aspect. Additionally, this work also introduces main hybrid variants of LECD. Possible future efforts to fully exploit LECD potential are also discussed.

Metals are indispensable engineered materials for day-to-day life. Researches focused on metallic surfaces with superlyophobicity (superhydrophobicity, superoleophobicity, underwater superoleophobicity and slippery characteristic) have attracted much attention recently. Nature is a magician that gives each organic life a unique advantage. Researchers have created a large number of biomimetic superlyophobic metallic surfaces through various approaches. These biomimetic superlyophobic metallic surfaces exhibit advantages in many applications, such as self-cleaning, corrosion resistance, anti-icing, and drag reduction. In this review, the specific fabrication and applications of biomimetic superlyophobic metallic surfaces were reported. The remaining challenges and future outlook of biomimetic superlyophobic metallic surfaces were preliminarily analyzed. It is hoped that the review will be essential for broadening the scope of potential applications of metals and providing a powerful reference for future research on metal-based advanced functional materials.

Directional droplet transport on functional surfaces with anisotropic wettability has shown great potential applications in various fields such as water harvesting, chemical micro-reaction, and biomedical analysis. However, the in-plane manipulation of the anisotropic droplet motion in more than two directions is still a challenge. Herein, through the fusion of inspirations from rice leaves, butterfly wings and Pitcher plants, we report a tridirectionally anisotropic slippery surface (TASS) with periodic step-like micro grooves for programmable droplet transport. TASS possesses a tridirectional droplet sliding behavior, i.e., the ultra-slipperiness along the grooves with a sliding angle of ∼ 2°, and the bidirectionally anisotropic sliding perpendicular to the grooves with sliding angle difference up to ∼ 50°, which is caused by the pinning effect of the step edge. Under the assistance of periodic vertical vibration, groove-features and droplet-volume dependent unidirectional droplets transports are realized on horizontally placed TASS, based on which two micro-reactors are designed to control the sequence of droplets merging and subsequent chemical reactions. Additionally, by utilizing the slipperiness (i.e., ultra-low sliding angle for liquid droplet) along the grooves simultaneously, programmable droplet transport under vertical vibration is further demonstrated on a tilted TASS. This work will provide a new avenue for the understanding of anisotropic wettability on asymmetric slippery surface, and thus offer a great opportunity to develop advanced interface for multidirectional droplet transport, chemical micro-reactor, etc.\ud \ud

In this study, a simple method without any additional chemical modification is proposed to fabricate underoil superhydrophobic surfaces with micro- and nano-hierarchical structures using a nanosecond laser system. The fabricated surfaces exhibited extreme superhydrophobicity and underoil superhydrophobicity with high contact angles of 153.8 ± 1.5° and 161.3 ± 1.1°, respectively. The results show that even after 20 abrasion cycles, the fabricated surfaces retained water repellency and self-cleaning performance under oil, while the superhydrophobicity in air was not resistant to wear. In addition, the fabricated brass meshes can also be used to separate oil in an oil-water mixture based on the prewetting induced underoil superhydrophobicity after being damaged. The separation efficiency was as high as 97.8%, which made them more appropriate for the oil-water separation than those based on superhydrophobicity. The proposed fabrication method is suitable for large-scale and mass production and provides a new avenue and possibility for further development of robust functional interface materials.

Magnesium alloys have been widely used in many fields such as the automobile industry, electronics industry, aerospace and optical equipment based on their excellent mechanical properties. However, the extremely poor corrosion resistance of magnesium alloys severely restricts its application and development in many fields. A superhydrophobic coating is prepared on the surface of magnesium alloy through laser processing technology and fluorination treatment. The modified laser processing surface has excellent superhydrophobic properties, making it difficult for corrosive media to contact the surface, and effectively improving the corrosion resistance of the surface. The corrosion resistance provided by superhydrophobic surfaces has been evaluated by electrochemical tests. The results show that, compared with bare surfaces and laser-textured surfaces, superhydrophobic surfaces have better corrosion resistance, which is of great significance for expanding the potential applications of magnesium alloys.

Antireflection functional surface has important applications in photoelectric detection, artificial blackbody, infrared imaging and other fields. In this study, the titanium alloy surface with high absorptivity was fabricated by nanosecond laser system. The effects of different scanning filling intervals on microstructure morphology and reflectance were studied. With the decrease of scanning interval, there are more and more micro clusters and micro holes on the surface, and the reflectance decreases gradually. When the scanning filling interval was reduced to 0.01 mm, the reflectance of titanium alloy surface could be decreased by 3% in the wavelength range of 400–1000 nm after laser treatment. In addition, in order to obtain a composite functional surface with superhydrophobic properties, the laser-processed surface was modified with a mixed solution of $1 H,\ 1 H,\ 2 H,\ 2 H$ -perfluorodecyltriethoxysilane and methanol. The maximum contact angle is 153.8° when the laser filling interval was 0.01 mm. It provides a reference for the preparation of antireflection and superhydrophobic composite functions surface.

The poor corrosion resistance of magnesium alloy has become the main reason restricting its application. In this paper, the layered double hydroxide (LDH) with good compactness was prepared on the surface of magnesium alloy by one-step hydrothermal method. The film thickness was 13 μm. The surface was injected with silicone oil to prepare the Liquid-infused surfaces (LIS). Electrochemical test studies show that the LIS has good corrosion resistance, and the lubricant and LDH on the surface can provide a double lasting physical barrier for magnesium alloy materials, effectively isolating chloride ions from corrosion to magnesium alloy substrates. In addition, the LIS is hydrophobic, which can reduce the contact area (CA) between the NaCl solution and the surface, and further improve the corrosion resistance of the magnesium alloy surface.

As two typical special wettability materials, superhydrophobic and superoleophobic surfaces are the most widely studied interfaces because of their excellent water-or oil-repellent ability. However, how to use a simple strategy to obtain those surfaces is still a huge challenge. On the other hand, corrosion tend to occur while using metallic materials, resulting in poor performance of metallic equipment and even serious safety hazards. In this work, a one-step strategy of nanosecond laser ablation was presented to construct the microstructures acquired by superhydrophobic and superoleophobic aluminum alloy surfaces. The superhydrophobic and superoleophobic properties of microstructured surfaces were obtained via high temperature and fluorosilane treatments on laser-processed surfaces, respectively, and the oil-repellent and corrosion resistance properties of both substrates were studied. The potentiodynamic polarization test shows that the superoleophobic surface had a better corrosion resistance than the superhydrophobic surface, which will provide an effective protection for the bare aluminum alloy. Meanwhile, the superoleophobic surface had good chemical stability. It is believed that the nanosecond laser technology can offer an effective strategy for constructing the microstructures acquired by large-area superhydrophobic and superoleophobic surfaces on aluminum alloy materials.

As two typical aspects of the wettability based on bio-inspired functional surfaces, superhydrophobic and anisotropic wetting properties have attracted much interest in practical applications. However, how to use a simple approach to realize those properties is still a huge challenge; simultaneously, the corrosion resistance is also important when the surfaces are introduced into more complex environments. In this paper, a simple and highly effective two-step approach for the fabrication of bio-inspired superhydrophobic and anisotropic wetting surfaces is reported. Aluminum alloy (Al) plates were first structured using nanosecond laser, and then were placed in an oven for low-temperature annealing (100 °C). The results show that the nanosecond laser ablation not only builds dual- and three-level structures inspired by lotus leaf and rice leaf but also oxidizes the Al materials, resulting in an oxide film covering on the surface. After the low-temperature annealing, the as-fabricated surfaces display the superhydrophobic and anisotropic wetting properties by adjusting the scan spacing of adjacent microgrooves. The potentiodynamic polarization and electrochemical impedance spectroscopy tests show that the as-fabricated surfaces have excellent corrosion resistance that can provide an effective protection for the Al materials. In addition, this approach can be applied to a broad range of metals (stainless steel, copper and titanium). This research will be instructive for the applications of functional materials with the properties of superhydrophobicity and anisotropic wetting.

This research studied the surface homogenization and morphology of a Ti-6Al-4V alloy using the longitudinal-torsional coupled ultrasonic vibration-assisted milling (UVAM) of a ball-end cutter, in which a method of continuous processing between the flat surface and the freeform surface connection was proposed. The cutting experiments compared the UVAM method with the conventional milling (CM) process by setting three parameters: the cutting speed, feeding rate, and depth of cut. The finished surface roughness, the in situ cutting force, and the topography of the surface are characterized in this paper. The surface roughness that resulted from UVAM ball-end milling was much better than the surface roughness of CM at high cutting speeds. In particular, there was a steep decrease of the average roughness rate from 0.668 μm at 4000 rpm to 0.161 μm at 5000 rpm. Moreover, the mean cutting force in ball-end milling using UVAM decreased by 20–40% compared to the CM process. The homogenization of the surface roughness also improved from 59.4 to 15.1% in the UVAM method compared to the CM method when the transverse-longitudinal ratio was taken into consideration. The cutting experiments have not only powerfully demonstrated the validity of the UVAM method but have also shown the beneficial effect that the UVAM process brings.

GH4169 superalloy has excellent properties such as high strength, high hardness and high temperature resistance, and is widely used in aerospace, automobile manufacturing, defense industry and biomedical fields. In the cutting process of superalloy, there are some problems such as serious tool wear and poor surface quality. The placement of micro-pit arrays on the rake face of cemented carbide tools can effectively improve the friction and wear resistance of the tools and improve the cutting conditions. In this article, ABAQUS software is used to simulate the micro-pit array tool orthogonal micro-cutting GH4169 superalloy. The cutting simulation of GH4169 superalloy was carried out by using micro-pit diameters of 35 μm, 30 μm, 25 μm, 20 μm and non-texture, respectively. The cutting-chip contact state, cutting force, cutting temperature and chip shape during the cutting process were analyzed. The study found that the placement of micro-pit texture can effectively reduce the cutting force during cutting and improve chip breaking. The micro-pit texture can intercept debris and hard particles on the bottom surface of the chip, reducing scratches on the rake face of the tool and the furrow effect of the hard particles, effectively improving the wear resistance of the tool.

Many biological surfaces with the multi-scale microstructure show obvious anisotropic wetting characteristics, which have many potential applications in microfluidic systems, biomedicine, and biological excitation systems. However, it is still a challenge to accurately prepare a metal microstructured surface with multidirectional anisotropy using a simple but effective method. In this paper, inspired by the microstructures of rice leaves and butterfly wings, wire electrical discharge machining was used to build dual-level (submillimeter/micrometer) periodic groove structures on the surface of titanium alloy, and then a nanometer structure was obtained after alkali-hydrothermal reaction, forming a three-level (submillimeter/micrometer/nanometer) structure. The surface shows the obvious difference of bidirectional superhydrophobic and tridirectional anisotropic sliding after modification, and the special wettability is easily adjusted by changing the spacing and angle of the inclined groove. In addition, the results indicate that the ability of water droplets to spread along parallel and perpendicular directions on the submillimeter groove structure and the different resistances generated by the inclined groove surface are the main reasons for the multi-anisotropic wettability. The research gives insights into the potential applications of metal materials with multidirectional anisotropic wetting properties.

In this work, the localized electrochemical micro additive manufacturing technology based on the FluidFM (fluidic force microscope) has been introduced to fabricate micro three-dimensional overhang metal structures at sub-micron resolution. It breaks through the localized deposition previously achieved by micro-anode precision movement, and the micro-injection of the electrolyte is achieved in a stable electric field distribution. The structure of electrochemical facilities has been designed and optimized. More importantly, the local electrochemical deposition process has been analyzed with positive source diffusion, and the mathematical modeling has been revealed in the particle conversion process. A mathematical model is proposed for the species flux under the action of pulsed pressure in an innovatively localized liquid feeding process. Besides, the linear structure, bulk structure, complex structure, and large-area structure of the additive manufacturing are analyzed separately. The experimental diameter of the deposited cylinder structure is linearly fitted. The aspect ratio of the structure is greater than 20, the surface roughness value is between 0.1&ndash, 0.2 &mu, m at the surface of bulk structures, and the abilities are verified for deposition of overhang, hollow complex structures. Moreover, this work verifies the feasibility of 3D overhang array submicron structure additive manufacturing, with the application of pulsed pressure. Furthermore, this technology opens new avenues for the direct fabrication of nano circuit interconnection, tiny sensors, and micro antennas.

Reducing the contact time of a water droplet on non-wetting surfaces has great potential in the areas of self-cleaning and anti-icing, and gradually develops into a hot issue in the field of wettability surfaces. However, the existing literature on dynamic behavior of water drops impacting on superhydrophobic surfaces with various structural shapes is insufficient. Inspired by the microstructure of lotus leaf and rice leaf, dual-level and three-level structures on plane and convex surfaces were successfully fabricated by wire electrical discharge machining on aluminum alloy. After spraying hydrophobic nanoparticles on the surfaces, the plane and convex surfaces with dual-level and three-level structures showed good superhydrophobic property. Bouncing dynamics of impact droplets on the superhydrophobic surfaces wereinvestigated, and the results indicated that the contact time of plane superhydrophobic surface with a three-level structure was minimal, which is 60.4% less than the plane superhydrophobic surface with dual-level structure. The effect of the interval S, width D, and height H of the structure on the plane superhydrophobic surface with three-level structure on contact time was evaluated to obtain the best structural parameters for reducing contact time. This research is believed to guide the direction of the structural design of the droplet impinging on solid surfaces.

Despite the success of previous methods for fabricating underwater superoleophobic surfaces, most of the surfaces based on soft materials are prone to collapse and deformation due to their mechanically fragile nature, and they fail to perform their designed functions after the surface materials are damaged in water. In this work, the nanosecond laser-induced oxide coatings on hydrophilic bulk metals are reported which overcomes the limitation and shows the robust underwater superoleophobicity to a mechanical challenge encountered by surfaces deployed in water environment. The results show that the surface materials have the advantage that the underwater superoleophobicity is still preserved after the surfaces are scratched by knife or sandpaper and even completely destroyed because of the hydrophilic property of damaged materials in water. It is important that the results provide a guide for the design of durable underwater superoleophobic surfaces, and the development of superoleophobic materials in many potential applications such as the oil-repellent and the oil/water separation. Additionally, the nanosecond laser technology is simple, cost-effective and suitable for the large-area and mass fabrication of mechanically durable underwater superoleophobic metal materials.

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 320.11 μm at a deposition rate of 0.887 μm 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.

Many biological surfaces with hierarchical microstructures exhibit obvious fog collection abilities. However, it is difficult to effectively fabricate a microstructured metal surface with fog collection performance using a simple but flexible method. Inspired by the abilities of microstructures of Sarracenia trichomes to capture fog and transport water, a series of hierarchical groove surfaces with the fog collection property were fabricated by wire electrical discharge machining (WEDM) method, and the fabricated surfaces showed the obvious superhydrophilicity. Moreover, the results show that the fabricated surface with the hierarchical groove structure had better water transport performance and higher fog collection efficiency compared with the smooth surface, and the abilities of water transport and fog collection are related to the number of low ribs on the surface with the hierarchical microgroove. The microstructure metal materials obtained in this study not only open up the potential applications of WEDM in fog collection, but also have wide application prospects in the fields of microfluidic system, biomedicine, and biological excitation system.

Ti6Al4V is often used in the manufacture of biomedical equipment due to its excellent properties such as light weight, high strength and good corrosion resistance in the physiological environment. Therefore, it is very important to form a non-toxic antibacterial surface on Ti6Al4V material. In this paper, a micro-nano manufacturing method of Ti6Al4V antibacterial surface was studied. In this process, the surface was firstly cut by low speed wire electrical discharge machine, and then the cut surface was hydrothermal treated. The antibacterial surface prepared by this process had the characteristics of non-toxic, stable structure, and would not cause bacteria to develop drug resistance. The preparation process is simple, friendly to the environment, and can realize mass production. The influence of different cutting times on the antibacterial surface morphology in the low speed wire electrical discharge machining was studied. The micron-grade surface obtained after three cutting times was of good quality, less molten material and high wear resistance. The influence of two etching agents mixed with different molar ratios on the micro-nano structure of antibacterial surface during hydrothermal treatment was analyzed. When the molar ratio of A and B solution was 14:1, the surface structure of the best size was obtained, and the wear resistance of the micro-nano structure surface was improved compared with the polished surface. The antimicrobial test results show that the surface of the prepared workpiece had obvious antimicrobial properties compared with the surface of the polished part after cultured for 24 h. The bacteriostatic rate of Escherichia coli was 49.55%. Based on the above, the research results of this paper have positive significance for the development of micro-nano antibacterial surface.

In this work, the reaction films were generated on the Ti–6Al–4V alloy by means of high-speed wire electrical discharge machining (WEDM-HS) technology in order to improve its microhardness and corrosion resistance. The microhardness was evaluated by using a nanoindentation tester. The corrosion behaviour was studied using measurements of potentiodynamic polarisation and electrochemical impedance spectroscopy. The experimental results showed that the processed alloys presented a higher microhardness than the matrix, and the thicker film on the surface had a greater microhardness. Additionally, the corrosion resistances of the processed alloys were superior, which could have been due to the lower corrosion current densities and the higher impedance values. Furthermore, the corrosion current densities of the processed alloys would decrease with thicker reaction films. This research provides important insights into the surface modification of titanium alloys.

Herein, we report for the first time the use of ethanol for the switchable underwater wettability on a rough titanium dioxide (TiO2) surface. The rough TiO2 thin films on the titanium surfaces are fabricated by the high speed wire electrical discharge machining (HS-WEDM) processes, and the resultant surfaces show the switch between underwater superhydrophobicity and oleophobicity via ethanol immersion and dark storage. The underlying mechanism of the switch is depicted, and the result shows that during the ethanol immersion and dark storage, the change of hydroxyl groups leads to the switch. Considering that the use of ethanol is time-saving and low-cost, we anticipate that the use of ethanol will open up a new way of surface wettability change.

The surface of the titanium alloy was blackened by a nanosecond pulsed laser, and two-dimensional and three-dimensional morphology observations and microstructure reflection measurements were performed by scanning electron microscopy (SEM), laser confocal scanning microscopy (LCSM) and microscopic angular resolution spectrometry (ARM). The effect of laser processing depth on reflectivity was studied by one-way filling scanning method. The results show that under different laser processing times, different microstructures are formed, and as the number of laser processing increases, the reflectivity of light decreases. In the 400–1000 nm band, the reflectance of the sample can be reduced to a minimum of about 1%.