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The cutting performance of textured polycrystalline diamond (PCD) tools on SiCp/Al composites is studied using an orthogonal cutting experiment. Micro-grooves with rounded corners are machined on the tool. Two texture parameters, namely the distance between the texture and main cutting edge and the texture spacing, were varied to investigate their influence on the cutting performance. The former is found to play a more important role in machining. Compared with non-textured tools, textured tools reduce the cutting force and tool wear, improve the surface quality, and change the chip flow direction to produce an anti-adhesion effect during cutting. To elucidate the cutting mechanism of textured tools, the cutting performance of tools with different micro-groove shapes is numerically studied using the finite element method. The simulation results indicate that a micro-groove-textured PCD tool with rounded corners reduces the interaction between the tool texture and chips, and the particles in the interface play a supportive and rolling role between the chip and tool surface.

In this paper, the characteristics and mechanism of laser-assisted machining (LAM) of C/SiC composites with different fiber orientations (0°, 45°, 90°, 135°) are studied. For the purpose of this study, a series of LAM experiments have been carried out and supported by a comparative analysis over the conventional machining (CM). Furthermore, the effect of fiber orientation on surface morphology, roughness, and sub-surface damage was explored. It is found that the surface quality of the workpiece treated by LAM is better than that of CM, and a lower surface roughness Ra value is obtained. It is shown that depending on different fiber orientations, the surface roughness decreases in different degrees. The roughness at 90° fiber orientation witnesses the maximum reduction, followed by 0° and 45° fiber orientation, and the roughness at 135° fiber orientation undergoes the slightest reduction. Moreover, surface micro-defects under LAM are significantly reduced, and fiber fractures are tidier. On the other hand, the matrix is mixed with fiber debris under high temperatures and sticks to the machined surface, filling and repairing surface pits and holes and hence improving the processed surface quality. These results provide new guidance for improving the machining quality of C/SiC composites.

The poor quality of the micro-hole in the conventional drilling (CD) of 3D needled Cf/SiC composites seriously limits its application in modern industry. Ultrasonic assisted drilling (UAD) is a hybrid machining technology that combines CD with ultrasonic vibration. When processing holes in the Cf/SiC composites, the UAD has great advantages of improving hole wall quality and reducing cutting force, and it has been widely applied to Cf/SiC manufacturing. This study mainly focuses on the influence of amplitude in UAD on the manufacturing of micro holes in the Cf/SiC. By analyzing the micro-morphology of the hole wall and outlet edge under different amplitude in UAD, the influence of amplitude on the fiber removal mode and material damage mechanism is studied. Meanwhile, the thrust force in CD and UAD is also obtained. The results show that the defects of the hole are reduced with the alteration of the fiber removal mode in UAD. And with the increase of the amplitude, the hole quality is further improved. However, the excessive amplitude leads to the damage of the matrix. The thrust force curve shows a “multi-peak” shape with a regular interval due to the layered structure of Cf/SiC in CD and UAD. Compared with the CD, the thrust force of UAD is reduced by up to 70.1% as the amplitude increases from 3 μm to 9 μm. Furthermore, the hammering effect caused by ultrasonic vibration alleviates the material damage around the outlet edge in UAD. With the increase of amplitude, the matrix damage and the fracture of the fiber around the outlet are alleviated. The fracture feature of the fiber around the outlet is more regular than the CD. Consequently, UAD is a beneficial method for Cf/SiC composites micro-drilling with better hole quality and it plays an important role in the future of Cf/SiC processing.

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.

Large-scale slender beam structures with low stiffness are widely used in the aviation field. There will be a great deformation problem in machining because the overall stiffness of slender beam parts is lower. Firstly, the cutting mechanism and stability theory of the Ti6Al4V material are analyzed, and then the auxiliary support is carried out according to the machining characteristics of the slender beam structure. The feasibility of the deformation suppression measures for the slender beam is verified by experiments. The experimental analysis shows that on the basis of fulcrum auxiliary support, the filling of paraffin melt material is capable of increasing the damping of the whole system, improving the overall stiffness of the machining system, and inhibiting the chatter effect of machining. This method is effective to greatly improve the accuracy and efficiency during machining of slender beam parts. On the premise of the method of processing support with the combination of fulcrum and paraffin, if the tool wear is effectively controlled, the high precision machining of large-scale slender beams can be realized effectively, and the machining deformation of slender beams can be reduced.

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.

With the development of marine transportation and underwater navigation technology, fluid drag reduction has become an international research hotspot as an important technical means to save energy and reduce environmental pollution. It has been found that the body surface structures of many organisms have unique drag-reduction properties. Therefore, it is feasible and important to replicate the morphological features of the body surface to the material surface. In this research, the structural features of biomimetic fish scales were summarized and extracted by observing the laminar arrangement features and morphology features of the surface scales of aquatic fish. Then, the arrangement features and morphology of fish-scales were abstracted into the oblique groove structure, and a three-dimensional model of the bionic fish-scale with a fan-shaped structure was constructed. The surface flow field of the bionic fish-scale was numerically simulated by COMSOL Multiphysics to revealing the mechanism of resistance reduction on the surface of the bionic fish-scale. The results indicate that the maximum drag reduction rate of the bionic fish scale surface is 8.40% compared with the smooth surface at a water speed of 0.6 m/s.

It has been researched that the surface structure of many organisms has unique resistance reduction properties and it is important to replicate the morphological features of the biological body surface on the material surface. So, a method for creating a biomimetic fish-scale surface using a laser is proposed by observing the laminar arrangement features of three common fish scales on the body surface, and a composite structure of bionic fish scale macrostructure and different microstructures of bionic fish scale were machined on on aluminium alloy surfaces. The surface morphology and elemental composition were characterized before the resistance reduction test. The results indicate that both the biomimetic fish-scale macrostructure and composite structure have an obvious effect of reduced drag, among which, maximum resistance reduction can be achieved 44.02% at a flow rate of 0.6 m/s for the bionic carp fish scale composite structure.

Aluminum foam is a kind of new material with a large number of holes distributed in aluminum alloy. It has the characteristics of lightweight, sound absorption, energy absorption and vibration reduction, and other porous materials. Aluminum foam has good acoustic performance. However, its excellent sound absorption ability is only reflected in the middle and high-frequency bands. Besides, the low-frequency sound absorption ability is very poor and the frequency band is narrow. Therefore, in this paper, different types of perforated aluminum foams with different parameters are combined to explore the influence on acoustic performance and find that the combination of large porosity perforated sample and aluminum foam has a better sound absorption effect. The unperforated sample is placed in front of the perforated sample to improve the sound absorption coefficient of the low and medium frequencies. Finally, different types of perforated aluminum foam samples were properly combined, and it was found through the test that almost all sound waves in the band of 1200 HZ~2000 Hz could be absorbed by the combined structure.

Carbon fiber-toughened silicon carbide composite matrix composite (Cf/SiC composite) occupies an important position in the field of aerospace due to its excellent mechanical properties. Because Cf/SiC composite have good high temperature resistance and hardness, machining traditional Cf/SiC composite is a difficult and time-consuming process. In this paper, two-dimensional braided Cf/SiC composite is used as the object, and a new laser-assisted machining orthogonal experiment system for processing Cf/SiC composite is developed by combining laser and conventional machining. The influence of laser-assisted orthogonal micromachining (LAOM) and conventional orthogonal micromachining (COM) input variables on the machining performance of Cf/SiC composite is mainly studied. By comparing the processing characteristics of the workpiece surface roughness, surface micro-topography, etc., the process benefits of laser processing variable changes are analyzed. The orthogonal experiment method is used to analyze the influence of factors such as machining speed, machining depth, and laser power on surface quality. The experiment results showed that the surface quality obtained by LAOM was better than that of COM. The machining depth had the most significant effect on the surface roughness, followed by the laser power, and the machining speed exerted the lowest effect on the surface roughness. Considering the surface quality requirements, the smallest surface roughness of the workpiece was obtained and the surface roughness Sa value was 3.841 μm with the optimal combination: a machining depth of 20 μm, a laser power of 20 w, and a machining speed of 300 mm/s. Microscopic analysis revealed that there were no pits, fiber tearing, pulling out, and other defects on the surface of the LAOM workpiece, and the surface was relatively flat and smooth.

Drilling is a kind of processing technology with a large proportion in mechanical processing, especially the drilling of deep hole, which is facing great challenges due to the high-strength properties of materials and debris-removal challenges. Because there is no obvious cutting force in the machining process and all conductive materials can be machined, microelectrical discharge machining (EDM) is playing an important role in deep hole drilling. In this study, micro-EDM technology was used for deep hole drilling on flexible bellows. Key technologies were discussed including workpiece positioning device, process control methods and drilling parameters selection. A special clamp was designed to solve the deformation problem of bellows positioning. In order to improve the consistency of the inlet and outlet of the deep hole, a double-sided guiding device was designed to reduce the radial deflection of tool electrode caused by the high spindle speed and long suspended stretch. The tool electrode compensation method was studied to improve the precision and aspect ratio of the deep hole. In addition, the influence of parameters such as spindle speed and oil flushing pressure on the drilling process was also analyzed. The study results show that the designed devices and process can meet the drilling requirements of the deep hole on bellows; the aspect ratio of the deep hole reaches 44:1.

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.

Severe plastic deformation occurs in micro metal cutting process; meanwhile, new surfaces are generated due to the material separation caused by ductile fracture. The energy required for the formation of the new surfaces is of kJ/m2, which should not be neglected in the analysis of micro-cutting. In this work, an analytical model is developed focusing on the analyses of the micro metal cutting process with no stable built-up edge, in which the effects of both edge radius and material separation are taken into account. The cutting tool edge geometry is simplified with the effective rake angle. On the basis of slip-line field theory, the equation of the cutting power is derived. Applying the minimum energy principle, two nonlinear equations are obtained, through which the shear angle and the minimum chip thickness can be estimated simultaneously. The model is examined through the experiments; the investigations show that the calculation results of cutting force and shear angle agreed with the experimental measurements very well. The effects of fracture toughness, shear yield stress, and friction angle to the micro-cutting process are investigated. The numerical results show that the friction angle affects the cutting force and the shear angle greatly.

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.

Due to the increasing scarcity of global water resources, water collection based on structural functional materials has become one of most potential ways to relieve the crisis. However, water collection functional surface with the high efficiency still encounters a bottleneck. In this paper, we constructed a rough surface with micro groove and nano grass composite structures on the copper substrate, and studied the influence of micro groove spacing on the falling radius of condensate droplets. The results show that the micro groove structure increases the nucleation of droplets, and the nano needle accelerates the removal of condensate droplets. The composite structure reduces the droplet shedding diameter, and the droplet nucleation first occurs at the edge of the micro groove. Therefore, reducing the tank spacing is conducive to the condensation and removal of droplets. In addition, the water collection experiment shows that the surface with micro/nano composite structures has higher collection efficiency than the smooth surface. These findings are useful for designing condensate collection systems with high performance.