Surface Microtexture Research Articles

Investigation on tool properties for the production of components with micro textured surfaces

Defined surface micrcotextures offer potential for the friction reduction in elastohydrodynamic contacts and can thus increase the energy efficiency of technical systems. The production of prostheses, where microtextured surfaces can provide anti-bacterial effects is another application area. To manufacture these components economically in large quantities, forming processes are to be aimed at. Since lightweight parts are crucial in most application areas, the forming of sheet metal is the subject of current research. A major aspect of the presented investigation is the behavior of tool materials for the production of such microtextured sheet metal parts. Applying microtextures of varying geometries to the tools is a key challenge. Limitations in the accuracy of electrical discharge machining processes for the fabrication of micro cylinders, prisms and cuboids are therefore analyzed on the high-speed steels 1.3343 and 1.3244. In addition, the tool surfaces are characterized regarding their friction properties with case hardening steel as a contact partner. In this paper, the tool friction is analyzed for the steel 1.7131 (16MnCr5) with an initial sheet thickness of t0 = 2.4 mm, which is often utilized for high-wear applications due to its high strength and toughness. In this context, the friction behavior of the wax-containing lubricant Beruforge 150 DL made for bulk forming processes is compared with zinc-free high-performance lubricants Raziol CLF 65-400 of varying viscosity.

Corrosion resistance and surface microstructure of Mg3 N2 /SS thin films by plasma focus instrument.

Utilizing a plasma focus (PF) instrument, magnesium nitride (Mg3 N2 ) thin films were synthesized on stainless steel substrates. Twenty five optimum focus shots at 8 cm distance from the anode tip were used to deposit the films at different angular positions regarded to the anode axis. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray diffraction (XRD) analyses were performed to assess the surface morphology and structural characteristics of Mg3 N2 films. Based on AFM images, these films were studied to understand the effect of angular position variation on their surfaces through morphological and fractal parameters. By increasing the angle, we verify that the grain size decreased from 130(0) nm to 75(5) nm and also the mean quadratic surface roughness of the films reduced in its average values from (28.97 ± 3.24) nm to (23.10 ± 1.34) nm. Power spectrum density analysis indicated that films become more self-affine at larger angles. Furthermore, the corrosion behavior of the films was investigated through a potentiodynamic polarization test in H2 SO4 solution. It was found that the ion energy and flux, varying with the angular positions from the anode tip, directly affected the nanostructured roughness and surface morphology of the samples. The electrochemical studies of films show that the uncoated sample presented the lowest corrosion resistance. The highest corrosion resistance was obtained for the sample deposited with 25 optimum shots and at 0° angular position reaching a reduction in the corrosion current density of almost 800 times compared to the pure stainless steel-304 substrate. HIGHLIGHTS: Mg3 N2 /SS films have been deposited at different angles by plasma focus (PF) instruments. The effect of angular position on the surface microtexture, morphological parameters, and corrosion features of the films was studied. The RBS measurement and X-ray diffraction are utilized to identify the crystalline phases and thickness of films.

Effect of clamping pressure on interfacial fusion morphology and fracture mechanism of CFRTP/Ti6Al4V laser bonding joint featuring blind hole surface microtextures

Carbon fiber reinforced thermoplastic composites (CFRTP) and titanium (Ti) alloy are both important lightweight materials in aircraft and aerospace applications, whose heterogeneous hybrid structure manufactured by laser joining technology is propitious to leverage the performance advantages of each component. The clamping pressure during the laser joining procedure is one of the most critical process parameters affecting the joint performance. Laser joining of CFRTP to Ti alloy (Ti6Al4V) under various clamping pressure is carried out, aimed to investigate the effect of clamping pressure on interfacial fusion morphology, mechanical property and fracture mechanism of bonding joint featuring blind hole surface microtextures. The fusion morphology and element distribution at joining interface are observed by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). Moreover, the fracture morphology and fracture mechanism are analyzed after tensile-shear test. The results show that an appropriate increase of clamping pressure improves the filling effect of melted resin to microtextures on Ti alloy surface, while too high pressure is inclined to induce the generation of pores and cracks at the joining interface. The fracture load of the joints increases and then decreases as the pressure rises, and it reaches a peak value of 3821.4 N corresponding to the optimal interfacial fusion effect when the pressure is 0.8 MPa. Significant distinctions exist in the main fracture mechanisms under different clamping pressure conditions, which lead to different fracture surface morphologies and mechanical performance of laser bonding joints.

Control of the wetting properties of stainless steel by ultrashort laser texturing using multi-parallel beam processing

The laser surface microtexturing is increasingly used for the production of surfaces with desired wetting characteristics (i.e., superhydrophobicity). For this not only precise but also fast laser processing is needed. Microtextures not based entirely on laser induced material self-organization require relatively tight focusing of the laser beam which can not be achieved using fast beam scanning systems. Therefore, in this work, the possibility to use parallel laser processing by multi-beam array for control of the EN 1.4301 (AISI 304) stainless steel surface was investigated. High-energy picosecond laser pulses were used to pattern the polished steel surface using 8 × 8 beam array with two different patterning strategies: mesh and dot. The multi-beam patterning inevitably brings some irregularities due to variation of properties of the beams in the array. However, after the investigation of the influence of laser patterning parameters on the wetting properties of the steel surface, it was determined that multi-beam mesh patterning allows obtaining superhydrophobic surface properties through the right combination of texture depth, surface chemical properties and laser induced surface ripples. The dot patterning was even more promising and was found suitable for obtaining a broad spectrum of wetting states ranging from superhydrophobic to superhydrophilic, when appropriate patterning parameters were used, mostly by controlling self-organized surface structure shape by changing texture period (laser spot overlap).

Electrical discharge micro-texturing using compound tool electrodes for tribological and wettability applications

ABSTRACT The present work consists of large-area surface texturing through die-sinking electrical discharge machining (EDM) using compound tool electrodes. The compound tools were machined through the wire electrical discharge machining (WEDM). The micro-textured surfaces incorporating array of nearly square/circular-shaped micro-dimples, rectangular micro-channels and square micro-pillars were analysed for their wetting properties. An increase in water contact angle (CA) indicated higher water repellence for textured surfaces with respect to the untextured ones. Further, improved frictional behaviour was elicited through tribological analysis via the ball-on-disc test, revealing a lower average coefficient of friction (CoF) compared to the untextured surface. The wear volume of textured surfaces (micro-channels and micro-pillars) exhibited a slightly higher value with respect to the untextured surface, which can be ascribed to the stress concentration from microfeatures. However, the micro-dimpled textured surface showed a relatively lower wear volume, presenting a suitable micro-texture for improved tribological characteristics.

Ice adhesion properties of periodic surface microtextured optically transparent superhydrophobic polydimethylsiloxane

There is a need for optically transparent surfaces which repel water and eliminate ice formation in applications, such as solar power generation. Surface microtexture has played an important role in controlling wetting properties and ice adhesion pressure. Here we report the effect of periodic surface microtexture on water wetting properties and ice adhesion pressure for optically transparent Polydimethylsiloxane. Laser ablation was used to produce surface microtexture on an aluminum substrate and was transferred onto a polydimethylsiloxane (PDMS) surface via hot embossing. The control of laser processing patterns with smooth area from 53.8% to 89.6% enabled fine-tuning of the wetting and ice adhesion properties. PDMS with a grid microtexture pattern has proven to be superhydrophobic and exhibited an ice adhesion pressure as low as 60.1 kPa, allowing the achievement of a water repellent and anti-icing surface. The surface wetting and anti-icing properties of the microtextured surfaces were quantified by the measurement of the receding contact angle (RCA), contact angle hysteresis (CAH), and ice adhesion pressure. Various publications have pointed to the ROA, RCA, or CAH as a predictor of low ice adhesion pressures for smooth surfaces. For microtextured surfaces, it was found that the CAH was the most accurate predictor of ice adhesion pressure.

Tribological Performance of Multiscale Micro-Textured H62 Brass Surface Fabricated by Micro-Milling and Wet Micro-Blasting

Abstract The cylinder block/valve plate interface in the axial piston pump has been proven to be easily worn out, which will increase power loss and reduce its efficiency. The valve plate surface is required to be manufactured with low viscous friction and wear. Multiscale micro-texture has been proven to improve surface tribological properties. However, there are few types of research in the effect of surface topography on the tribological performance of multiscale micro-textured surfaces. The purpose of this study is to explore how the multiscale micro-texture on H62 brass affects its sliding friction behavior on 38CrMoAl. Based on micro-milling and wet micro-blasting, the multiscale micro-textured surface was manufactured on H62 brass. The wet micro-blasting was applied in the H62 brass after the surface micro-texturing. The surface topography of multiscale micro-textured samples processed by three abrasive grit sizes accompanied by two processing times was comprehensively measured in terms of height, feature, functional, and functional volume parameters. The tribological performance of multiscale micro-textured H62 brass was characterized by disk-on-disk frictional experiments. Through analyzing the relationship between surface morphology and tribological properties, the antifriction mechanism of the multiscale micro-textured surface was analyzed from the perspective of 3D surface roughness parameters. The friction coefficient of the multiscale micro-textured surface processed by the combination of micro-milling and wet micro-blasting decreased with the increasing grit size and micro-blasting time.

The impact of helical slide honing on surface microtexture compared to plateau honing process through relevant characterization methods.

The cylinder engine surface texture has a major influence on the functional performances of the ring-pack tribo-system. The cylinder engine surface microtexture manufactured by plateau honing (PH) and helical slide honing (HSH) processes have been analyzed using white light interferometry (WLI), and stereometric analysis. The approaches in three-dimensional (3-D) white light interferometer measurements and surface stereometric analysis are important for the correct interpretation of 3-D local surface texture features and can be applied in mathematical models for calculating the friction. The samples were divided into two groups: plateau honing (PH) samples and helical slide honing (HSH) samples to discuss the obtained results, according to the honing techniques obtained after several stages: the rough and finish honing and final stage. The obtained results demonstrated that the surface of group PH has the higher values of root mean square height (Sq=1.83 μm) and fractal dimension (Df=2.74 ± 0.01), while the lowest values of root mean square height (Sq=0.63 μm) and fractal dimension (Df=2.60 ± 0.01) were found for HSH samples. These values highlight that the PH samples are more irregular (both as surface and topography) in comparison with HSH samples. HIGHLIGHTS: We characterized the micromorphology of surface microtexture in plateau and helical slide honing. The nanostructure morphology was investigated using the white light interferometry, fractal and stereometric analyses. The surface topography during the HSH process has different characteristics than the PH process and can be used to obtain better friction and lubrication performances.

Application of friction–speed model to evaluate runway surface microtexture and macrotexture: a case study

ABSTRACT Runway skid resistance should be evaluated and maintained periodically to sustain aircraft operation safety. This study focuses on evaluating runway skid resistance in terms of surface microtexture and macrotexture and determining how aircraft operations affect these characteristics. The friction–speed model developed by the Harmonisation of European Routine and Research Measuring Equipment for Skid Resistance of Roads and Runways–Laboratoire Central des Ponts et Chaussées was selected due to its consistent and rational results. The grip number values measured using a grip tester for 19 continuous months on 2 runways of the Taoyuan International Airport were analysed as a case study. Research outcomes showed that the microtexture of dense grade asphalt concrete was not considerably different from that of stone mastic asphalt concrete, but the latter exhibited markedly better macrotexture than the former. Aircraft landing operation significantly reduced skid resistance at the touchdown zone. In particular, macrotexture was decreased. However, aircraft behaviour at high-speed exits exerted more negative influences on microtexture than on macrotexture. Accordingly, designing a runway surface layer with improved macrotexture at the touchdown zone is recommended and special attention should be given to the microtexture evaluation of the area located immediately before a high-speed exit point.

Laboratory study of the skid resistance of asphalt concrete made of local low performances aggregates by partially replacing sand with olive mill waste

This paper presents the results of a laboratory experimental study that explores the skid resistance of asphalt concrete mixtures made of local low-performance aggregates by partially replacing sand with olive mill waste (OMW).OMW was mixed with aggregates using a dry process by replacing sand with contents of 5%, 7%, 10% and 15%. The mechanical performances of the mixtures were evaluated using the Marshall and Duriez tests. A modified accelerated polishing machine was used as polishing equipment, and a British pendulum tester (BPT) was used to test the skid resistance of the samples. Finally, texture parameter analysis was performed using scanning electron microscopy (SEM) and MountainsMap software to assess the effect of OMW on the friction coefficient evolution.Using a new road wheel for a modified version of an accelerated polishing machine, which is normally used to determine the polished stone value of aggregates, the results showed that the addition of OMW up to 10% conferred a better skid resistance in comparison to normal asphalt concrete. The presence of olive mill waste in the mixture until 15% guarantees a gain of 22%-29% in skid resistance after polishing compared with the reference mix. Indeed, from texture parameter analysis, it was observed that there was differential wear of the lightweight aggregates (OMW) compared to the other aggregates during the polishing process, which created a new surface microtexture; that had new peaks; and led to a good level of friction compared to the mixtures without OMW. In general, it was found that OMW is a promising modifier for asphalt mixtures with both engineering and economic merits.

Theoretical and Simulation Analysis on Fabrication of Micro-Textured Surface under Intermittent Cutting Condition by One-Dimensional Ultrasonic Vibration-Assisted Turning

Fabricating micro-textures with specific parameters (size, shape, and distribution) on the surface of mechanical components has the potential to improve the tribological performance. When the ultrasonic vibration is applied to depth direction of turning, the micro-textured surfaces with specific dimples can be generated in a simple and effective way. Under the intermittent cutting condition, the generation mechanism of the micro-textured surface, processed by this one-dimensional ultrasonic vibration-assisted turning (1D UVAT), was further carried out. A novel theoretical model was firstly proposed from the perspective of geometric kinematics, which can reveal the influence of three intersection states between the flank face and cutting trace (η1 < tan α, η1 > tan α > η2 and η2 > tan α) on the size, shape, and distribution of micro-dimples, generated under intermittent cutting conditions. Then, a simulation model was built to predict the surface topography and dimple profile under different processing parameters. The results show that the processing parameters, including clearance angle, spindle speed, and vibration amplitude, have an important influence on the intersection state. By choosing the proper clearance angle, spindle speed, or vibration amplitude, the different intersection states can be realized, and the corresponding size, shape, and distribution of micro-dimples will be changed accordingly. With the increase of the nose radius and feed rate, the dimple width and distance between adjacent dimples along feed direction can both increase accordingly. The simulation results not only confirm the feasibility of the proposed theoretical model, but also show that the discrete or continuous micro-dimples, with different sizes and specific shapes, can be controllably generated on cylindrical surface by 1D UVAT under intermittent cutting conditions.

Study of deterministic surface micro-texture generation in ultra-precision grinding considering wheel oscillation.

Ultra-precision grinding is crucial for manufacturing high-end optics and molds, while the unbalanced wheel vibration is inevitable and becomes even more critical in surface generation, which resulted in undesired waviness and micro-texture on the ground surface. In this paper, to understand and control the micro-texture generation, a theoretical model has been developed to predict the deterministic surface micro-texture generation resulted from unbalanced tool vibration in ultra-precision grinding, in which the overlap trajectories of grinding wheel with an arc cutting edge were analyzed and calculated. The simulation work was performed and a double phase mechanism involved in deterministic textural pattern and structure has been revealed. Both theoretical and experimental results proved that phase shift is an important factor to determine micro-texture evolution in the ultra-precision grinding process. On this basis, a novel tool path strategy has been proposed to fabricate deterministic micro-structure by coordinating oscillation motion of the grinding wheel and phase shift control, in which a rhombus-shaped micro-structure array can be generated. A small adjustment for the phase shift was conducted and it was found that the more complex micro-texture with different textural patterns and micro-structure can be machined. The results indicated that the phase control for the tool path planning is an effective method to fabricate flexible and tunable micro-texture surfaces in ultra-precision grinding.

Micro-textured silicone-based implant fabrication using electrospun fibers as a sacrificial template to suppress fibrous capsule formation

Conventionally, macro-textured surfaces comprising several hundred micrometer-sized patterns are used to minimize silicone-based breast implant complications, including capsular contracture. However, because of the recent cases of breast implant-associated anaplastic large cell lymphoma from macro-textured implants, there is a strong demand for nano- or micro-textured silicone implants with dimensions smaller than sub-micrometers. Herein, we propose a simple and cost-effective topographical surface modification strategy for silicone-based implants. Several hundred nanometer to sub-micrometer wide groove-type micro-textures were fabricated on a polydimethylsiloxane surface using electrospun polyvinylpyrrolidone fibers as a sacrificial template. The aligned and randomly oriented micro-textures were prepared by controlling the electrospun fiber orientation. In vitro experiments demonstrated that the micro-textured polydimethylsiloxane was cytocompatible and suppressed differentiation of fibroblasts into myofibroblasts. Importantly, the aligned micro-texture promoted the polarization of macrophages into the anti-inflammatory M2 phenotype. Long-term in vivo studies established that the micro-textures potently suppressed various factors affecting foreign body reactions by downregulating profibrotic cytokine gene expression and reducing the fibroblast and myofibroblast counts, the cells playing important roles in the immune response. Thus, the thickness and collagen density of fibrous capsules were decreased, demonstrating that the micro-textured surface effectively inhibited capsular contracture. Although the aligned micro-textures contributed to the polarization of macrophages to the M2 phenotype both in vitro and in vivo, foreign body reaction by both the aligned and randomly oriented micro-textures are similar.

Molecular dynamics simulation on the merging movement of nanodroplets on materials surface

The movement of droplets on materials surface is a common phenomenon and may be affected by many factors such as surface wettability and initial spacing of nanodroplets. In this study, the movement process of two nanodroplets were calculated by using molecular dynamics simulation. For obtaining the influence rule of different surface and different initial spacing on the movement process of nanodroplets, the snapshot, the key time points during the movement process and the contact angle(CA) change were studied. The results show that surface microtexture can affect the merge of nanodroplets and make the surface more hydrophobic. The smaller the initial spacing, the earlier the merge starts. In addition, the texture significantly improves the hydrophobicity of copper surface, but have a marginal effect on the wettability of Si surface. Meanwhile, the increase of number of nanodroplets shortens the time of fusion.

Theoretical and experimental exploration into the fluid structure coupling dynamic behaviors towards water-lubricated bearing with axial asymmetric grooves

The work studies the fluid structure interaction (FSI) dynamic behaviors of water-lubricated bearing with axial asymmetric grooves. Revised FSI models with consideration of cavitation and turbulent effects are put forward. Stimulations are consistent with the literature and experimental data, indicating the correctness of the model. Effects of groove types, locations in ascending/descending zones towards the dynamic behaviors are explored in details systematically. The separation effects of the local asymmetric grooves coupled with the rotation effects further enhances the hydrodynamic effects, which will directly lead to the growth of maximum pressure values and the load carrying capacity (LCC). Research fruits have important guiding significances for the optimization design of the surface microstructures and micro-textures, especially the design of axial asymmetric grooves for such bearings.

From the micromorphology of paleoweathering fronts to paleoenvironmental analysis: A case study of the Cretaceous dune fields of Sanfranciscana Basin, Brazil

The work investigated the paleoenvironmental significance of kaolinite-rich weathering fronts developed during the Cretaceous in stabilized dune fields of Sanfranciscana Basin in Brazil. To this, was conducted a multi-scale analysis from the outcrops of paleosols to mineral grains and soil pores. The macro and micromorphology of paleoweathering fronts allow recognizing weathering features and estimating the porosity and hydraulic parameters (permeability, capillary pressure, and saturated hydraulic conductivity). Scanning electron microscope analyses were conducted to investigate surface microtextures of quartz grains for weathering process characterization based on dissolution microfeatures. Energy-dispersive X-ray spectrometry was utilized to identify chemical elements of clay minerals. The major and trace elements were analyzed using a Philips X-ray fluorescence (XRF) spectrometer (PW 2440). Our results showed that weathering fronts expand through preferential water paths (pipe and finger flow) in bedding planes in response to textural and porosity contrasts related to the bimodality (i.e., the difference of grain size distribution between overlapped sedimentary structures) of aeolian deposits. The dissolution features present in quartz grains, such as etching, pitting, total dissolution of grains, iron coatings, and booklets of well-developed kaolinite, reveal an increase in humidity and the pedogenetic kaolinization process typical of a humid tropical environment. These weathering patterns coincide with cooling events between the Albian and the Cenomanian report in the literature. Our study indicates that during the Cretaceous, the Sanfransicana Basin underwent climatic amelioration and a rise in water table level, which likely enhanced dune stabilization and the formation of an extensive geomorphic surface.

Application of Surface Microtexture Technology

Background: Surface condition of mechanical parts has a significant impact on the machine performance. The use of surface microtexture technology based on bionics is an effective method to improve the comprehensive performance of the surface of machine parts. Surfaces with microscopic pits, convex-hulls, microgrooves, and scale textures can reduce wear, improve friction, enhance lubrication, decrease drag, and minimize noise. Surface microtexture technology has been widely used in many types of machinery, embodying various properties in working conditions. Objective: The purpose of this study is to provide an overview of recent patents and related research on surface microtexture technology, and to serve as a guide for future applications. Methods: The paper describes the development of surface microtexture technology, reviews the representative patents on surface microtextures and their applications in industrial field, including cutting tools, bearings, gears, blades, etc. The advantages and disadvantages of various surface microtextures are discussed. Results: In this study, the influence of surface microtexture on friction, wear, lubrication, sealing, noise reduction, and hydrophobicity is examined through the analyses of various microtexture produts. The main problems in future development of surface microtexture technology are summarized. Conclusion: Machine elements with different types of microtexture perform different functions. The geometrical parameters of the microtexture contribute greatly to the surface properties of the machine elements. Therefore, the surface performance of machine elements can be improved by designing and optimizing the geometric parameters of the microtexture. In the future, more patents focused on surface microtexture will be reported.

Study on optimization of texture parameters in micro-textured cutting of titanium alloy based on ABAQUS

Tools with micro-textured surfaces can successfully lessen the primary cutting surfaces and decrease tool friction. To conduct additional research on the impact of microtexture parameters (depth, width, and spacing) on the cutting of titanium alloy. In this paper, a two-dimensional finite element simulation model for titanium alloy cutting using micro-textured tools is established by using Abaqus software, based on the response surface method, the influence of different microtexture parameters on the chief cutting surfaces and the interaction of microtexture depth, microtexture width,and microtexture spacing is obtained, it is concluded that the effect of the depth of microtexture on the chief cutting surfaces is the most significant, the microtexture spacing is the second, and the microtexture width is the weakest. The optimum parameters of the microtexture tool are microtexture depth 20μm, microtexture width 30μm, and microtexture spacing 80μm. The chief cutting surfaces is 208.26 N.

A Corner-Cube-Cell Solar Array for Improved Capture of Optical Power and Increased Generation of Electrical Power

A corner-cube-cell (CC-cell) array of solar cells is introduced in this article for use with a multichannel form of maximum power point tracking (MPPT). The CC-cell effectively captures internal reflections, enabling the use of nontextured silicon surfaces with prolonged electron-hole lifetimes and greater optoelectronic conversion efficiencies, in comparison to microtextured surfaces. The theoretical and experimental results show marked improvements for the CC-cell array, over the conventional flat-cell array, as seen by an increased generated electrical power density of 50.9% at midday and an increased generated electrical energy density of 34.0% over the full day. The gains result from the CC-cell's geometry and its compatibility with a multichannel form of MPPT. Ultimately, the proposed technology shows great promise for realizing low-cost and high-performance implementations of silicon solar arrays.

Application of Micro-Textured Surface Prepared by an Integrated Molding Process in Sustainable Turning of Ti-6al-4v

Application of Micro-Textured Surface Prepared by an Integrated Molding Process in Sustainable Turning of Ti-6al-4v