•An efficient and good drilling performance of micro-textured drilling tools was proposed in this study.•A surface topography analysis experiment was used to predict the micro-textured drilling tools ...can solve drilling defects.•3D FEM simulation for drilling of Inconel 718 using micro-textured drilling tools is carried out and the results are experimentally validated.•Different micro-texture shapes (groove, convex and pit), were studied the effect of drilling performance.•A secondary cutting phenomenon that reduces the drilling performance is proposed, and increasing the width of the micro-texture can avoid it.
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In this study, finite element method (FEM) was used to study the performance of three different geometrically shaped micro-textures, namely grooved micro-texture, convex micro-texture and pit micro-texture drilling tool in the processing of Inconel 718 superalloy. By changing the key parameter of spindle speed, the purpose is to discuss the influence of changing drilling parameters on the machining performance of micro-textured drilling tools. Through the analysis and comparison of experiments, the results show that the micro-texture of the rake face can be well prepared by laser surface texturing technology, and the micro-textured drilling tools can alleviate the defects caused by conventional drilling tools. The simulation model is established and the changes of thrust force, drilling temperature and tool wear are compared and analyzed. In addition, the secondary cutting phenomenon of micro-texture during the drilling process was proposed for the first time, and the influence of micro-texture width on the secondary cutting phenomenon is analyzed. The results show that micro-texture implantation has lower thrust force, drilling temperature and tool wear, it is proved that micro-texturing technology can effectively improve the drilling process.
Friction continues to account for the bulk of energy losses in mechanical systems, with an estimated 23% of the world’s total energy consumption used to overcome friction. Concentrated polymer ...brushes (CPBs) have recently attracted significant scientific and industrial attention, given their ability to achieve superlubricity (i.e., coefficients of friction below 0.01); however, understanding the mechanistic interactions underlying their wear performance has been largely overlooked. Herein, we employ a custom-built optical test apparatus to investigate the inter-dependencies between CPBs and laser-produced surface texture (LST), assessing for the first time the friction, film thickness, and wear behavior in situ and simultaneously. Recent developments in picosecond laser etching allowed us to graft CPBs atop the finest laser-etched matrix of micron-sized dimples reported in literature to date. At low sliding speeds, combined CPB–LST reduces the coefficient of friction to 0.0006, while increasing the CPB durability by up to 34% through a lateral support mechanism offered by the textured micro-features. Furthermore, the imaging results shed light on CPB failure mechanisms. Both these mechanisms of lateral support and failure propagation impact the wear resistance of CPBs and are important in the development of CPBs for future applications (e.g., in low-speed bearings functioning under controlled abrasive wear conditions).
In this paper, a superhydrophobic surface with mechanical durability was prepared on 6061 aluminum (Al) alloy by combining laser surface texturing (LST) and micro-arc oxidation (MAO) techniques ...followed by chemical immersion treatment. The effects of processing on Al alloys with different texturing spacings on the surface morphology, roughness, surface wettability, and corrosion resistance of the subsequently formed composite coatings were analyzed. The results show that a superhydrophobic surface was obtained with the water contract angle (WCA) of 158.3 ° and the roll-off angle of 9.5 ° at a texture spacing of 300 μm. This was due to the fact that the surface microroughness texturization process created by LST on the surface increased the generation of surface nanostructures, and combined with the natural nanostructure possessed by MAO, unique " double " nanostructure was formed on the surface. This surface structure increased the area of fluoride attachment, reduced the solid-liquid contact area, and decreased the adhesion of droplets to the surface, resulting in higher hydrophobicity. Electrochemical corrosion experiment showed that the corrosion current density of LM-300 was 2 orders of magnitude lower than that of the LM-0 sample, clearly demonstrating better corrosion resistance. In addition, the prepared superhydrophobic surface presented excellent mechanical durability, and in the ceramic zirconia cyclic abrasion experiment, the superhydrophobic surface was able to withstand 61 cycles of abrasion at a pressure of about 2.5 kPa.
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Building-integrated photovoltaics (BIPV) offer a promising approach for reducing carbon emissions in the buildings sector. In BIPV system, color control harmonizes photovoltaic modules with the ...architectural design and surroundings. In this paper, a structural coloring technique based on the optical interference effect of dielectric multilayers is applied to the cover glass of Si-based photovoltaic modules to realize efficient and aesthetically appealing BIPV modules. A trade-off between the color brightness and the short-circuit current density (JSC) of colored BIPV modules is found, which are highly dependent on the multilayers structure and the surface roughness of the cover glass. We also evaluate the glare-effect and the color angular dependence of these modules and find that these two obstacles can be effectively suppressed by introducing the surface texturing to the cover glass. However, roughening the glass surface can also contribute to an additional optical loss and a decrease in the JSC. Therefore, the design of structured colored glass should be adapted depending on the intended purpose. Finally, we demonstrate colored PV modules with high conversion efficiencies of >21% and minimal JSC loss of <5%, while maintaining the adequate anti-glare effect and the color angular independence.
•We apply structural color technology with dielectric multilayers to the cover glass of Si-based photovoltaic modules and realize efficient and aesthetically appealing BIPV modules.•In general, a color brightness and the short-circuit current density (JSC) of colored PV modules are inversely related and highly dependent on the multilayers structure and surface roughness of cover glass, but complex interplays between multilayers and surface textures are also observed.•The glare-effect and the color angular dependence of these modules are effectively suppressed by introducing the surface texturing to the cover glass.•We have fabricated colored PV modules with high conversion efficiencies of >21% and minimal JSC loss of <5%, which are one of the most efficient colored modules with similar colors.
•Surfaces with periodically changed wettability were produced by a ns marking laser.•Heat transfer was investigated on uniformly and non-uniformly wettable surfaces.•Microporous surfaces with ...non-uniform wettability enhance boiling heat transfer.•The most bubble nucleations were observed in the vicinity of the microcavities.•Results agree with the predictions of the nucleation criteria.
Microstructured uniformly and non-uniformly wettable surfaces were created on 25-μm-thin stainless steel foils by laser texturing using a marking nanosecond Nd:YAG laser (λ=1064nm) and utilizing various laser fluences and scan line separations. High-speed photography and high-speed IR thermography were used to investigate nucleate boiling heat transfer on the microstructured surfaces. The most pronounced results were obtained on a surface with non-uniform microstructure and non-uniform wettability. The obtained results show up to a 110% higher heat transfer coefficients and 20–40 times higher nucleation site densities compared to the untextured surface. We show that the number of active nucleation sites is significantly increased in the vicinity of microcavities that appeared in areas with the smallest (10μm) scan line separation. Furthermore, this confirms the predictions of nucleation criteria and proves that straightforward, cost-effective nanosecond laser texturing allows the production of cavities with diameters of up to a few micrometers and surfaces with non-uniform wettability. Additionally, this opens up important possibilities for a more deterministic control over the complex boiling process.
•A flexible hinge mechanism is used in a non-resonant vibration generator to generate larger vibration amplitudes over a range of frequencies. Another advantage of this device is that it can use not ...only a single frequency but also multiple frequencies at the same time. Therefore, complex texture can be generated in one step.•The principles of this vibration assisted surface texturing process both on the cylindrical and face surfaces of a cylinder were detailed analyzed.•Surface generation models both for cylindrical and flat surfaces of a cylinder are established to serve as the vehicle for generating the desired surface topography. The predictive accuracy of the proposed surface generation models were ascertained by experimental results.•The uniform surface textures on face surface of a cylinder can be generated by proposed vibration controlling method.
Surface texturing with designed micro-structures exhibits numerous novel functional characteristics and features as compared to ordinary smooth surfaces or surfaces generated by the conventional customary manufacturing processes. Though several micro-scale surface textures generating techniques have been used to fabricate surface textures, most of these techniques are either of low efficiency or lack the flexibility to fabricate sophisticated surface topographies. In this study, a non-resonant vibration generator was used to control the micro surface texturing generation process. The principles of this vibration assisted surface texturing process are analyzed. Furthermore, surface generation models for both the cylindrical and flat surfaces of a cylinder are formulated to serve as a vehicle for generating the desired surface topography. Finally, surface texturing experiments were conducted, and complex micro textured topographies were successfully fabricated.
Surface textures have been of great interest within the tribology community with nearly 1500 papers published on this topic in the past two decades. With the pursuit of low emissions and ...environmental sustainability, the application of surface texturing to mechanical systems to lower friction and control wear is attracting increasing attention. There is no doubt that certain textured surfaces can have a beneficial effect on tribological performance but it is widely agreed that the optimization of textures should be carried out based on specific requirements of applications. The purpose of this review article is to summarize the current state of the art in surface texturing applied to mechanical applications (cutting tools, piston-ring & cylinder liners, sealing and journal bearings) from the following aspects: application requirements, numerical/experimental testing and validation, and tribological performance of textured surfaces (wear and friction), as well as the limitations in texture designs when applied to certain applications. Patterns/grooves in the micron-scale are the most typical shapes been studied, and benefits of partial texturing are applicable for most of these mechanical applications. Friction reduction of up to 34.5% in cutting tools, 82% in piston-ring & cylinder-liners, 65% in seals and 18% in journal bearings have been observed by experimental tests. Based on primary evidence from the literature, the last section provides general suggestions on current gaps in understanding and modelling and suggestions for future research directions.
Micro-textures applied on rubbing surfaces have gained tremendous attention in the tribological community. Numerous studies deal with the deduction and testing of beneficial micro-textures. ...Nevertheless, not all questions have been answered yet. Will texturing really deliver as good effects as frequently claimed? Are there optimum texture designs? Are there occasions where texturing could enhance the tribological performance but is questionable from other perspectives?
Therefore, ball-on-disc experiments are carried out with a special emphasis on the relative position of micro-texture and counter body. Furthermore, transient EHL simulations are performed, addressing the effects of structural parameters and relative texture's position on the tribological performance. Finally, meta-modeling with subsequent optimization is applied to predict numerically derived optima and robust texture designs.
•The relative position between micro-texture and contact area influences friction and wear.•Structural texture parameters determine the tribological behavior.•Tribo-simulations and Meta-Modeling support the deduction of robust texture designs.•Appropriate micro-texture designs depend on the applied load.•Shallow textures with a diameter close to contact area are considered to be beneficial.
In this research, three types of vein-bionic texture patterns inspired by five kinds of leaves (Forsythia, Clausena lansium, Ash, Pipal, and Apricot) were designed and fabricated on the raceways of ...the shaft washers of cylindrical roller thrust bearings (CRTBs) through a fiber laser marking system. A vertical universal wear test rig was used to obtain the coefficient of friction (COF) of bearings under starved lubrication, with a customized tribo-pair. The wear losses of the shaft washers and the worn surfaces were characterized. The influence of different veins (chief, primary, secondary) and vein-structure characteristics (pattern symmetry, number of veins) on the tribological behavior of vein-bionic textured CRTBs is investigated and discussed. The results show that the original vein-bionic (V) pattern inspired by the Ash has the best friction-reducing performance, while the texture with the no-chief vein (NC) obtained by Clausena lansium has the best wear resistance. The chief vein mainly contributes to the low friction by enhancing the secondary lubrication effect and facilitating the formation of a protective nylon film. A reasonable mechanism for improving the tribological properties of resulting textures is proposed.
The metal-thermoplastic hybrid structure has been widely employed in the aviation and aerospace industry. In this work, we developed a feasible way of laser surface texturing to address the poor ...adhesion between PEEK and 6061-T6 aluminum alloy. With the laser surface modification on 6061-T6 aluminum alloy, the PEEK/6061-T6 friction lap joining strength was improved significantly. The experimental results showed that the tensile shear strength between PEEK and 6061-T6 with laser textured surfaces achieved the maximum of 48.14 MPa. The enhanced bonding strength was attributed to the mechanical interlocking at the interface between PEEK and 6061-T6 caused by periodic micro-pores and nano-particles. After the progress of laser surface texturing, the double-scale hierarchical structures were produced on the surface of modified 6061-T6 alloy, leading to the formation of superhydrophobic or hydrophobic surfaces. Besides, quantitative fractal analysis of 6061-T6 surfaces was performed to study the relation between the morphology of 6061-T6 surface and the adhesion property of PEEK and 6061-T6. The results indicated that the superhydrophobic surface of 6061-T6 exhibited higher adhesion property with PEEK than the hydrophobic surface. A flawless interface was observed in the joint of PEEK and 6061-T6 with the superhydrophobic surface, compared to the voids observed at the interface of PEEK and 6061-T6 with the hydrophobic surface.
•A method of laser surface modification was developed to address the poor adhesion between PEEK and 6061-T6.•The modified 6061-T6 surfaces evolved to be hydrophobic or superhydrophobic.•The modified PEEK/6061-T6 FLJ joint achieved the maximum tensile shear strength of 48.14 MPa.
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