Surface Microtexture Research Articles

Study on synergistic friction between surface micro-texture and hot-pressing filling coal-to-oil soot solid lubricant

To study the combination of triangle micro-texture (TM) and coal-to-oil soot (CS) solid lubricants to improve the tribological properties of steel balls and disc surface, three filling processes (hot pressing, mechanical pressing, and alcohol coating) were used to prepare CS composite lubricating film on TM surface (TM-CS). The tribological behavior of CS was examined across various experimental parameters using the WTM-2E controlled atmosphere micro-friction and wear tester. The structure and morphology of CS were scrutinized with high-resolution transmission electron microscopy. The tribological mechanisms were involved by X-ray photoelectron spectroscopy and scanning electron microscopy. The results reveal that the hot press filling is the most effective method, which can achieve a 97 % filling rate. The optimal tribological performance is observed at a speed of 900 rpm and a load of 2.5 N. Under this condition, the TM-CS surface reduces by 75 % in the average friction coefficient (AFC) and 88 % in the average wear scar diameter (AWSD) compared to the TM surface. The analysis of the friction mechanisms indicates a substantial synergistic effect between the TM surface and the CS solid lubricant. This synergy is significantly potentiated by the electrostatic adsorption phenomenon and the impact of airflow at high rotational speeds, which play a pivotal supportive role in enhancing tribological performance.

An Experimental Study Based on Surface Microtexture of Medical Devices

An Experimental Study Based on Surface Microtexture of Medical Devices

Anti-friction and anti-infection properties on biomedical Ti3Zr2Sn3Mo25Nb alloy driven by high-precision cross-elliptical micro-texture and copper coating

A surface modification method was proposed to boost tribological properties of near β-type biomedical titanium alloy Ti3Zr2Sn3Mo25Nb (TLM) by synergistic application of micro-texture and copper coating. In calf serum, the friction coefficient on the TLM surface decreased by approximately 17 % when the micro-texture density was 15 %. Furthermore, the texture-free modified TLM surface exhibited reduced friction coefficients under various loads, with a maximum decrease of nearly 30 %. Additionally, the wear mass and wear rate of TLM surface were as low as 1.97 times and 2.34 times of commercial Ti6Al4V alloy when combining micro-texture with copper coating, respectively. The anti-friction mechanism can be attributed to enhanced load-bearing capacity due to micro-texture and the self-lubricating effect by copper coating. Importantly, introducing copper coating on micro-textured surface will catalyze protein denaturation to generate graphite-like carbon films during friction with an anti-friction property, meanwhile, exhibited significant antibacterial activity, with the antibacterial rate of 99.41 % and 94.70 % against Staphylococcus aureus and Escherichia coli, effectively improving postoperative infections.

Wettability-Oriented Laser Microgrooving Process on Cemented Carbide Surface.

Surface micro-texture has been shown to enhance wettability and reduce wear on cutting tools. However, there is limited research on how laser parameters impact the dimensional accuracy of surface texture and its wettability. This study focuses on producing arrayed groove textures on WC/Co cemented carbide surfaces using Nd: YAG laser, evaluating the effect of the laser parameters on surface topography and texture accuracy through microscopic observation and simulation. The results indicate that, with laser parameters such as a number of passes less than 5, approximately 16 W power, scanning speed of 100-150 mm/s, and pulse frequency of 30 kHz, the error between the groove width and laser spot diameter was 4.7%. Additionally, the study explores the impact of the groove texture on surface wettability using the solid droplet method and XPS analysis. Comparative experiments reveal that increased surface roughness enhanced oleophobicity, with surfaces exhibiting high texture accuracy and integrity showing improved oleophobic and spreading properties. Thus, the precise regulation of laser processes is crucial for maintaining surface texture integrity and enhancing surface wettability.

Study on force-thermal characteristics of ball end milling cutter with chamfered edge and micro-textured flank face

Micro-texturing can significantly improve the cutting performance of tools. During the titanium alloy cutting process, the cutting depth is relatively small, and the flank face mainly bears the friction. To overcome this issue, this study attempts to explore the influence of the micro-texture of the flank surface and chamfered edge on the cutting performance of the ball end mill. It is proved that the micro-texture of the flank surface of ball end milling cutter can reduce the actual contact area and friction, and thus reduce the cutting force. The increase of chamfering width and Angle changes the chip state and provides a good heat dissipation environment. Under the combined action of chamfered cutting edge and micro-texture, the force and heat in the milling process are reduced, and the tool life is increased to some extent. The results show that the optimum combination of chamfering and micro-texture parameters is as follows: chamfer angle is 10°, chamfer width is 100 µm, diameter of the micro-circular pit is 70 µm, pit spacing is 125 µm, and distance from cutting edge is 110 µm.

Fishbone-like micro-textured surface for unidirectional spreading of droplets and lubricity improvement

Directional spreading of droplets on asymmetrical micro-structures surface has attract interests of researchers for its significant application potential in scientific and engineering fields. In this paper, a fishbone-like micro-textured surface (FMS) is proposed, which exhibits efficient unidirectional spreading behavior of droplets (maximum forward-backward spreading coefficient up to 3.7). The effect of geometrical characters on spreading performance are studied, thus facilitating obtainment of optimal parameters of the FMS. Such type of micro-structured surface is arranged on noncontact areas of pin-on-disk tribological system. Experimental results demonstrate the FMS has lubrication retention effect, resulting in reduction of friction and wear. The maximum reduction rate of friction coefficient is 63.3 % compared with the bare specimen.

Synergistic Effects of Graphene-added Lubricants and Surface Micro-texturing on the Tribological Behavior of Thrust Roller Bearings

The synergistic effects of graphene additive and surface micro-texturing on the friction and wear properties of rolling bearings are still a research gap. To this end, the tribological behavior of dimples textured thrust roller bearings (81107TN) are investigated under starved lubrication. The lubricants contained different mass fractions (0.06 %, 0.10 % and 0.14 %) of graphene. The evenly distributed dimples (diameter: 60 µm or 250 µm; depth: 1 µm or 8 µm) were manufactured only on the raceways of the shaft washers. By comparing the coefficients of friction (COF), wear losses and worn surfaces, the influence of various dimples dimensions and mass fractions of graphene on the tribological behavior of rolling bearings is discussed. The results show that appropriate dimple parameters and a suitable mass fraction of graphene can synergistically have a positive effect on the tribological properties of bearings. In this work, the textured group, with a dimple-diameter of 60 µm and a dimple-depth of 1 µm, can provide the best comprehensive friction-reducing and wear-reducing performance for the mass fraction of graphene with 0.10 wt%. Compared to the smooth bearings lubricated with base oil, its mean COF is reduced by 31 % and its wear loss by 35 %. This work can be a valuable reference for the improvement of rolling bearings and lubricants.

Surfalize: A Python Library for Surface Topography and Roughness Analysis Designed for Periodic Surface Structures.

Surface roughness measurement is an integral part of the characterization of microtextured surfaces. Multiple established software packages offer the calculation of roughness parameters according to ISO 25178. However, these packages lack a specific set of features, which we hope to address in this work. Firstly, they often lack or have limited capabilities for automated and batch analysis, making it hard to integrate into other applications. Secondly, they are often proprietary and therefore restrict access to some potential users. Lastly, they lack some capabilities when it comes to the analysis of periodic microtextured surfaces. Namely, common parameters such as the peak-to-valley depth, spatial period and homogeneity cannot be calculated automatically. This work aims to address these challenges by introducing a novel Python library, Surfalize, which intends to fill in the gaps regarding this functionality. The functionality is described and the algorithms are validated against established software packages or manual measurements.

Drag increase behavior of micro-textured concave titanium surface generated by oblique laser etching

Titanium alloy has been widely used in the clinical preparation of artificial jawbone implants due to its excellent mechanical properties and biocompatibility. Artificial bone implantation drug-carrying research can realize the targeted release of drugs at the lesion, however, it is still at the technical bottleneck in inhibiting the sudden release of drugs. In this paper, based on the typical wettability model, a drug-loading and release-retarding method for artificial titanium jawbone drug-storage microcapacitor has been proposed by studying the oblique laser etching process of the inner surface of the drug-storage capsule and by investigating the resistance-enhancing mechanism of the texturization of concave surface of the inner wall. Using the oblique laser etching texture, the contact angle measurement reveals that when the laser frequency is 40KHz, the laser pulse width is 11 ns, the scanning speed is 130 mm/s, and the laser incidence angle is kept at 30° and the number of processing is one, the minimum surface contact angle can be obtained is only 8°. By combining the “3 + 2″ nanosecond laser etching device with the laser depth of focus theory, a curved surface laser etching process method was proposed. A titanium alloy jawbone with drug-carrying cavities was printed using SLM 3D printing technology, and the drag-enhancing effect of the texture was verified using sodium fluorescein labeling method, and it was found that the hydrophilic microtexture had a significant drag-enhancing effect on the liquid flow in the microfluidic channel.

Insect-inspired breathing interfaces: investigating robustness of coating-free gas entrapping microtextured surfaces under pressure cycles

Numerous natural and engineering scenarios necessitate the entrapment of air pockets or bubbles on submerged surfaces. Current technologies for bubble entrapment rely on perfluorocarbon coatings, limiting their sustainability. Herein, we investigated the efficacy of doubly reentrant cavity architecture towards realizing gas-entrapping microtextured surfaces under static and dynamic pressure cycling. The effects of positive (>1 atm), negative (<1 atm), and positive–negative cycles on the stability the gas entrapment inside individual doubly reentrant cavities were studied across a range of pressures, ramp rates, intercycle intervals, and water-column heights. Remarkably, the fate of the trapped air under pressure cycling fell into either of the following regimes: the bubble (i) monotonically depleted (unstable), (ii) remained indefinitely stable (stable), or (iii) started growing (bubble growth). This hitherto unrealized richness of underwater bubble dynamics should guide the development of coating-free technologies and help us understand the curious lives of air-breathing aquatic and marine insects.

Collective wetting transitions of submerged gas‐entrapping microtextured surfaces

AbstractNumerous natural and industrial processes entail the spontaneous entrapment of gas/air as rough/patterned surfaces are submerged under water. As the wetting transitions ensue, the gas diffuses into the water leading to the fully water‐filled state. However, the standard models for wetting do not account for the microtexture's topography on collective wetting transitions. In other words, it is not clear whether the lifetime of n cavities arranged in a one‐dimensional (I‐D) line or a two‐dimensional (II‐D) (circular or square) lattice would be the same or not as a single 0‐D cavity. In response, we tracked the time‐dependent fates of gas pockets trapped in I‐D and II‐D lattices and compared them with wetting transitions in commensurate 0‐D cavities. Interestingly, the collective wetting transitions in the I‐D and the II‐D arrays had a directionality such that the gas from the outermost cavities was lost the first, while the innermost got filled by water the last. In essence, microtexture's spatial organization afforded shielding to the loss of the gas from the innermost cavities, which we probed as a function of the microtexture's pitch, surface density, dimensionality, and hydrostatic pressure. These findings advance our knowledge of wetting transitions in microtextures and inspiring surface textures to protect electronic devices against liquid ingression.

강원도 북부 동해안 연안류에 의해 운반되는 석영입자표면미세조직의 변화

강원도 북부 동해안 연안류에 의해 운반되는 석영입자표면미세조직의 변화

Theoretical Modeling and Surface Roughness Prediction of Microtextured Surfaces in Ultrasonic Vibration-Assisted Milling

Textured surfaces with certain micro/nano structures have been proven to possess some advanced functions, such as reducing friction, improving wear and increasing wettability. Accurate prediction of micro/nano surface textures is of great significance for the design, fabrication and application of functional textured surfaces. In this paper, based on the kinematic analysis of cutter teeth, the discretization of ultrasonic machining process, transformation method of coordinate systems and the cubic spline data interpolation, an integrated theoretical model was established to characterize the distribution and geometric features of micro textures on the surfaces machined by different types of ultrasonic vibration-assisted milling (UVAM). Based on the theoretical model, the effect of key process parameters (vibration directions, vibration dimensions, cutting parameters and vibration parameters) on tool trajectories and microtextured surface morphology in UVAM is investigated. Besides, the effect of phase difference on the elliptical shape in 2D/3D ultrasonic elliptical vibration-assisted milling (UEVAM) was analyzed. Compared to conventional numerical models, the method of the cubic spline data interpolation is applied to the simulation of microtextured surface morphology in UVAM, which is more suitable for characterizing the morphological features of microtextured surfaces than traditional methods due to the presence of numerous micro textures. The prediction of surface roughness indicates that the magnitude of ultrasonic amplitude in z-direction should be strictly limited in 1D rotary UVAM, 2D and 3D UEVAM due to the unfavorable effect of axial ultrasonic vibration on the surface quality. This study can provide theoretical guidance for the design and fabrication of microtextured surfaces in UVAM.

Exploring the physicochemical traits, antifungal capabilities, and 3D spatial complexity of hydroxyapatite with Ag+[sbnd]Mg2+ substitution in the biocomposite thin films

The silver/magnesium doped hydroxyapatite (AgMgHAp, Ca10−x-yAgxMgy(PO4)6(OH)2, xAg=0.05 and yMg=0.02) nanocomposites coatings were deposited on Si substrate using the dip coating technique. The resulting coatings were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), Fourier transform infrared (FTIR-ATR) spectroscopy, atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS). The EDS analysis highlighted the presence of the constitutive elements of the silver/magnesium doped hydroxyapatite (AgMgHAp) nanocomposites coatings. The surface microtexture of the AgMgHAp was assessed by atomic force microscopy (AFM) technique. The AFM data suggested the obtaining of a uniform deposited layer comprised of equally distributed nanoconglomerates. FT-IR studies highlighted the presence of vibrational modes associated with the phosphate and hydroxyl groups. No bands associated with silver or magnesium were observed. The XPS analysis highlighted the presence of the constituent elements of hydroxyapatite (Ca 2p, P 2 s, O 1 s), as well as dopants (Ag 3d, Mg 1 s and Mg 2p). The antifungal evaluation of AgMgHAp coatings was carried out using the Candida albicans ATCC 10231 fungal strain. The results of the antifungal assay revealed that the AgMgHAp coatings exhibited a strong inhibitory antifungal activity. Furthermore, the data highlighted that the AgMgHAp inhibited the development of biofilm on their surface. The results revealed that the antifungal activity of the coating varied based on the duration of incubation. On the other hand, the data also showed that AgMgHAp nanocomposites coatings inhibited the fungal cell adhesion and development from the early stages of the incubation. In addition to morphological analysis, we additionally take advantage of AFM images to investigate and explore the domain of fractal and multifractal analysis applied to the films under evaluation. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. Our studies indicates that nanocomposite coatings made from AgMgHAp demonstrate strong antifungal properties. These results suggest the potential of AgMgHAp nanocomposite coatings as a promising solution for developing innovative antifungal devices in biomedical applications.

Scalable Surface Micro-Texturing of LLZO Solid Electrolytes for Battery Applications

Scalable Surface Micro-Texturing of LLZO Solid Electrolytes for Battery Applications

Study on the Micro-cutting Mechanism of 7075 Aluminum Alloy with Pre-fabricated Surface Microtextures

Study on the Micro-cutting Mechanism of 7075 Aluminum Alloy with Pre-fabricated Surface Microtextures

Early Oligocene record of an “iceberg alley” in the Weddell Sea from quartz sand microtextural analysis at ODP Site 696

Abstract The greenhouse to icehouse transition at the Eocene-Oligocene boundary (34 Ma) marked the appearance of continental-scale glaciation in Antarctica. The material recovered from Ocean Drilling Program Site 696 is the only record spanning this major climatic shift in the Weddell Sea region. Using scanning electron microscopy, quartz microtextures in 13 samples across the Eocene-Oligocene transition were analyzed to understand the degree of glacial modification and the transportation history of the &amp;gt;150 µm material. The quartz grains were visually grouped, characterized, and interpreted by grain outline, relief, and surface microtextures. Glacial textures are present throughout the entire interval (34.4–33.2 Ma), with the proportion of iceberg-rafted grains in each sample decreasing into the early Oligocene (33.6 Ma), accompanied by an increase in the frequency of eolian and sea-ice-rafted grains. Mass accumulation rates reveal that the flux of iceberg-rafted debris increased coincident with the flux of eolian and sea-ice-rafted grains following 33.6 Ma, suggesting a strong coupling between land-ice development and high-latitude atmospheric processes. When compared with other Antarctic climate proxy data sets, the intensification of ice rafting at Site 696 occurred after ice-sheet inception in East Antarctica. The prominent influx of terrigenous material after 33.6 Ma points to strengthened glacial conditions accompanied by major changes in the environment of the Weddell Sea region, supporting the idea of a high-latitude role in climate perturbations, in agreement with interpretations of other global proxies.

Sedimentary records of giant landslide-dam breach events in western Sichuan, China

Introduction: Landslide-dammed lake outburst floods (LLOFs) are common natural disasters in high-mountain regions, posing serious safety threats to residents’ livelihoods and properties and causing major damage to engineering facilities. Giant landslides and river damming events commonly occur in the Eastern Tibetan Plateau in southwestern China. Dam failure generate LLOFs that form outburst deposits (ODs). This phenomenon is particularly common in some giant ancient landslide-dammed lakes.Methods: This study conducted a detailed investigation of the sedimentary characteristics of large-scale landslide-dammed lake outburst deposits in the Diexi Reach of the Upper Minjiang River and Tangjiashan Reach of the Tongkou River Basin, West Sichuan Plateau, China. Meanwhile, typical evidence of high-energy ODs was recorded.Results and Discussion: The longitudinal distribution of these ODs is similar to an elongated fan-shaped terrace along the river channel, presenting a distinctive sedimentary disordered–sub-ordered–ordered sequence from upstream to downstream. Several typical units of “sedimentary facies” are developed in the OD profiles, such as boulder units deposited by high-energy outburst flood (OF) events and the gravel and sand units representing pulsating-flow sedimentary environments during the recession stage. The grain size frequency curves are bimodal, and the granularity accumulated curves are upward convex, which reflect that the detrital characteristics of the sediment source area are mainly composed of coarse gravel and boulders. This indicates that the coarse gravel sediment gradually become decreased from upstream to downstream. Moreover, the OD hydrodynamic intensity displays a gradual weakening, and sediment sorting is improved. From upstream to the downstream, the mean particle-size and sorting of the ODs gradually decrease. The skewness become larger, and the kurtosis of the ODs is distributed in all the types. In addition, the different combinations of quartz sand surface microtextures indicate the transformation from high-to low-energy impacts over a short distance, which is controlled by flood hydrodynamics and regime.Significance: These sedimentary characteristics of ODs explain the hydrodynamic changes during the propagation of OFs, and are also important records for distinguishing between ODs, and “normal” floods.

Optical tunability with superlattice hyperbolic metamaterial coatings

Optical tunability is demonstrated with multi-metal hyperbolic metamaterial (HMM) structures on varying substrate surfaces. A systematic uniaxial modeling methodology is adapted from classical approaches to extract the anisotropic permittivity of the films to identify epsilon-near-zero (ENZ) behavior over a wide range of metal volume fractions (φ). The anisotropic model accuracy is quantified by a mean squared error (MSE) with the presented modeling routine resulting in a MSE < 35 for all samples. The optical model thicknesses were verified with transmission electron microscopy (TEM) imaging and measurements. This study also demonstrates the ability to tune the optical responses in the visible-to-infrared frequencies with surface microtexturing and applied strain with HMM coatings on flexible Kapton substrates. Furthermore, the structured films and modeling procedure lay the groundwork for future studies on coupling the anisotropic optical and thermal properties for control over advanced multifunctional thin-film coatings.

Inverse Design of Photonic Surfaces via High throughput Femtosecond Laser Processing and Tandem Neural Networks.

This work demonstrates a method to design photonic surfaces by combining femtosecond laser processing with the inverse design capabilities of tandem neural networks that directly link laser fabrication parameters to their resulting textured substrate optical properties. High throughput fabrication and characterization platforms are developed that generate a dataset comprising 35280 unique microtextured surfaces on stainless steel with corresponding measured spectral emissivities. The trained model utilizes the nonlinear one-to-many mapping between spectral emissivity and laser parameters. Consequently, it generates predominantly novel designs, which reproduce the full range of spectral emissivities (average root-mean-squared-error < 2.5%) using only a compact region of laser parameter space 25 times smaller than what is represented in the training data. Finally, the inverse design model is experimentally validated on a thermophotovoltaic emitter design application. By synergizing laser-matter interactions with neural network capabilities, the approach offers insights into accelerating the discovery of photonic surfaces, advancing energy harvesting technologies.