Specific Surface Texture Research Articles

Development of Microstructure on Titanium Implant Surface Using CO2 Laser Processing

Background: Dental biomaterials made of titanium are commonly used. It depends on the implant surface texture to improve fixation and prevent the unwanted adhesion of bone cells. This study aimed to investigate whether continuous laser beam carbon dioxide (CNC - CO2) lasers produce specific textures on titanium surfaces with micrometer-sized indentations that influence cell behavior. Materials and method: (CNC - CO2) red laser device; with a fundamental wavelength of λ=10600 nm and power pulses of 34 W were applied, and textures on the surface of titanium discs were achieved. Results: Excellent degrees of uniformity and repeatability were achieved for the desired portions of the surface by creating different surface textures. The surface topography and chemical composition of the specimens were investigated by scanning electron microscopy, electron dispersive spectroscopy, X-ray diffraction, and surface roughness measurements. Also, a laser power of 34 watts raised the surface roughness, Ra (1.71 nm), and Rz (1.99 nm). Conclusion: Titanium surface textures with unique qualities can be formed in response to an increased heat input. When excessive laser power was used, the measured roughness increased because of instantaneous re-melting. The use of a right continuous-wave (CNC - CO2) laser on titanium used in dental implants can form specific surface textures.

Synthesis, characterization, and gas sensing application of crumpled CdO sheets prepared in alkaline media

CdO crumpled sheets have been synthesized by microwave-assisted irradiation in alkaline solutions of NH4OH and NaOH, respectively, and in presence of a surfactant. The morphology of CdO samples have been investigated using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). X-ray diffraction analysis (XRD) has been used to determine the cadmium oxy/hydroxide crystalline phases of CdO formed during synthesis and successive annealing at 300 °C. Crystallite sizes of CdO nanostructures obtained from NH4OH and NaOH reagent-assisted synthesis are 44 nm and 57 nm, respectively. The specific surface area (SSA), lattice parameter, X-ray density, dislocation density, macrostrain, and texture coefficient (TC), have also been determined. The optical characteristics of CdO samples were investigated using UV reflectance (DRS) and K-M plot. NO2 gas detecting capabilities of CdO nanostructures have been investigated at low working temperature of 150 °C. When compared to its NaOH counterpart, the CdO sample prepared by NH4OH reagent-assisted synthesis demonstrated a superior sensitivity to NO2, being demonstrated even at the low concentration of 0.14 ppm, with excellent selectivity.

Multiscale Wear Simulation in Textured, Lubricated Contacts

Specific surface textures may reduce the friction and increase the lifting forces in lubricated contacts. For the detrimental operating condition of mixed friction, wear is induced by the solid contact. In this study, a methodology for wear calculation in textured, lubricated contacts is presented that considers the wear-induced surface topography evolution. Based on the Reynolds differential equation, the mass-conserving cavitation model according to Jakobsson, Floberg, and Olsson (JFO), a wear-dependent asperity contact pressure curve and the wear equation according to Archard, wear in a wedge-shaped, textured lubrication gap was calculated. The results show the wear behavior of textured lubrication gaps. Based on the wear simulations, the tribological behavior of the textured surfaces compared to smooth surfaces is discussed. It is evident that textures, which improve the tribological performance in the hydrodynamic lubrication regime, are not necessarily associated with low wear values in a lubrication condition in the mixed friction regime. The analysis of the wear-dependent parameters initially showed a ‘recovery’ of the tribological system with increasing wear until the performance decreased again after a specific reversal point. This behavior is attributed to the relative position of the surface textures in the lubrication gap.

The Effect of Initial Texture on the Plastic Deformation of Gradient Aluminum.

The effect of specific processing-induced surface textures in gradient aluminum has not yet been investigated. A dislocation-based multi-scale framework is employed to explore the influence of various initial shearing textures and the depth from the surface of the region featuring each texture on the macroscopic behavior of gradient aluminum. By assigning different textures to the same grain size gradient aluminum sample, the initial texture was found to significantly affect the plastic deformation and macroscopic behavior of gradient aluminum. Specifically, the {111} texture can enhance the strength-ductility synergy, and this effect is dependent on the depth from the surface where the texture is located. This texture can lead to a slow stress/strain gradient in the assigned texture region and a sharp stress/strain gradient in the grain size gradient region connecting this region with the coarse grain region. Particularly, the sharp stress/strain gradient can result in extra strengthening by adjusting the stress/strain localization. These findings provide valuable insights for the design and optimization of surface textures in gradient aluminum.

Effects of anisotropic and isotropic LIPSS on polymer filling flow and wettability of micro injection molded parts

In micro injection molding, the specific cavity surface texture and roughness directly influence the polymer flow and the heat transfer between polymer melt and mold. In this work, two different types of laser-induced periodic surface structures, linear and hexagonal, were generated, and their impact on the flow length in micro injection molding was evaluated.A complete investigation of the surface treatment effect on the polymer flow was carried out, comparing the performance of an untreated cavity surface with surfaces modified by LIPSS. The phenomenon was examined by localizing the weld lines created by the polymer flowing in two parallel channels having different surface treatments. Several cavity inserts were treated by varying the LIPSS process parameters to generate surfaces with different micro- and nanostructures directions and periodicity. Furthermore, the paper addresses the hydrophobicity achieved on the micro molded surfaces replicated from mold inserts with different LIPSS-based surface topography. Mold surfaces with linear and hexagonal LIPSS and the respective molded parts were analyzed by optical profilometry and scanning electron microscopy to characterize the cavity surfaces replication and localize the weld lines on the micro injection molded parts.

Effect of intermittent cutting behavior on the ultrasonic vibration-assisted grinding performance of Inconel718 nickel-based superalloy

Ultrasonic vibration-assisted grinding (UVG) is a promising precision machining method for difficult-to-cut materials. This study investigated the intermittent cutting behavior in UVG of Inconel718 nickel-based superalloy and its effect on the grinding temperature, grinding force and workpiece surface quality. A novel material removal probability model was established to analyze the impact depth and the contact length between the abrasive grain and the workpiece considering the interference of grinding trajectories in UVG. Results indicated that the intermittent cutting behavior in UVG caused a decrease in the contact length by 42%, resulting in a significant reduction of grinding temperature and grinding force by 40% and 41%, respectively. It was suggested that the increase in the cutting depth was better than the increase in the workpiece infeed speed for enabling the lager material removal rate in the tangential UVG due to the lower grinding force ratio and the less change of specific grinding energy. A specific surface texture was generated on the ground surface due to the phenomenon of frequent contact and separation, enabling the reduction of workpiece surface roughness by maximum 20%.

Surface properties of cork: Is cork a hydrophobic material?

Knowledge of the surface tension of cork and its hydrophobicity is of critical importance in many applications of this material at the interface with solid or liquid phases. The conventional technique based on contact angle measurement by sessile drop is not adapted to this naturally textured material and does not allow to accurately determine its hydrophobic character. A study based on capillary rise measurement is reported. A statistical distribution of the surface tension of cork is obtained, based on experiments performed on cork powder with various liquids and using a specific data processing to take into account the intrinsic heterogeneity of cork. This gives a surface tension of 22.6 (±1.2) mN·m−1, with a polar component at 5.2 (±0.5) mN·m−1 and a dispersive component at 17.4 (±1.6) mN·m−1. With a water contact angle of around 90°, cork shows an intermediate hydrophobic/hydrophilic behaviour. Locally, the specific surface texture and chemical composition can reinforce either the hydrophobic or the hydrophilic character. This critical analysis invites reflection on the notion of surface hydrophobicity as it can be determined macroscopically by a contact angle measurement and as defined at the molecular level by the free enthalpy of sorption of water.

Surfactant effects on structural, optical and morphological characteristics of microwave irradiated CdO nanostructures

Surfactant based microwave irradiated and alkaline medium involving wet chemical method was adopted to prepare CdO nanostructures. The phase evaluation of prepared and annealed CdO nanostrucutures has been analyzed by XRD and FTIR. The average size of the crystallite was estimated to be 54 nm for the NH4OH reagent and 60 nm for the NaOH reagent in the assisted synthesis. Specific surface area, lattice parameter, X-ray density, dislocation density, microstrain, texture coefficient and Williamson Hall have been calculated from the XRD profile. UV transmittance and the K-M plot of DRS and PL spectra were used to examine the optical properties of CdO nanostructures. The spherical and rod-like structures of CdO prepared with strong and weak alkaline medium have been recorded through SEM and TEM micrographs. The four-step process of hydration, intermediate formation, metal hydroxide formation, and metal oxide formation confirms that the experiment in the presence of 0.1 M sodium hydroxide results in rod-shaped nanostructures.

Special Issue on Tribology of Additive Manufacturing

Special Issue on Tribology of Additive Manufacturing

Engineering Properties of Nagar Parkar Plutonic & Volcanic Rocks as a Construction Aggregates, District Tharparkar, Sindh Province Pakistan

The purpose of this paper is to study the important engineering properties of the volcanic rocks present with the Nagar Parkar Granites located from Sindh University Campus Jamshoro 5 h 44 min (355.3 km) via Hyderabad - Badin Road and 5 h 57 min (323.5 km) via Naukot - Mithi Road and Islamkot, the rocks look suitable for pavement and concrete aggregates. Number of standard tests were conductedted. Which included; Specific Gravity, Gradation, Soundness, Particle shape and Surface Texture Absorption Index, Abrasion Resistance, Deleterious Materials,, in addition to moisture content and Fineness modulus. Geologically there are two main components known as Pink Granites and Grey granites on the basis of the plagioclase / orthoclase mineral component. Results of the standard tests depicted that both Pink Granites and Grey Granites samples have different characteristics especially concerning abrasion resistance. After comparing the obtained results with standard specifications showed that both samples can produce aggregates that are suitable for pavement but only Pink sample can produce concrete aggregates. It was also assumed that there should be a technical control in the crushing circuit to produce the required gradation.

The Influence of Isotropic Surface Roughness of Steel Sliders on Ice Friction Under Different Testing Conditions

Ice friction is affected by various system and surface-related parameters such as ice temperature, ambient air temperature and humidity, relative sliding velocity, specific surface pressures and surface texture (waviness, roughness) as well as the macroscopic geometry of the samples. The influences of these parameters cannot be easily separated from each other. Therefore, ice friction is a very complex tribological system and it is challenging to draw sound conclusions from the experiments. In this work, ice friction experiments with stainless steel samples that have different isotropic surface roughness values were carried out. Two tribological experimental setups were used: (i) an inclined ice track where the sliding velocity of the freely sliding steel samples was determined and (ii) an oscillating tribometer, where the coefficient of friction was assessed. For both experimental setups, the environmental parameters such as air temperature, relative humidity and ice surface temperature as well as the test parameters such as normal load and surface pressure were kept as constant as possible. The results of the experiments are discussed in relation to the ice friction mechanisms and the friction regimes.

Preparation and Properties of Graphene/Nickel Composite Coating Based on Textured Surface of Aluminum Alloy

This study carried out a novel duplex surface treatment on aluminum alloy base to explore the potential improvement of wear and corrosion resistance. Regular arrayed dimple surface texture (DST) and groove surface texture (GST) were fabricated by using laser processing on 6065 aluminum alloy matrix (6065Al). Electrochemical deposition of Ni and Graphene/Ni coatings on textured surface was then performed in electrolytes with concentrations of 0, 0.5, 1 and 1.5 mg graphene. Surface morphology such as diameter of dimple and width of groove measured by C-PSCN stereo microscope presents addition of graphene helps to refine and homogenize the coating. Corrosion resistant properties of the duplex surface treatment were examined by electrochemical corrosion tests and wear resistant properties were tested by UMT-Tribo Lab friction and wear tester in a dry sliding condition at room temperature. Electrochemical corrosion tests results show that the corrosion resistance of samples is related to the specific surface texture and the dimple texture can improve the electrical corrosion parameters, such as the electrode potential, greatly. Friction and wear tests show that the textured Gr/Ni electroplating coating with the 1.5 mg graphene content has best wear properties under vertical friction and each index, such as the coefficient of friction and wear trace width, are superior to other conditions of samples.

Local risk indicators – Consensus report of working group 2

In implant dentistry, plaque control and oral hygiene practices are essential to limit the risk of complication and failure in the long term. All conditions around an implant in function that influence the load and pathogenicity of the microbiota are considered local risk indicators. They concern the prosthetic suprastructure design and the possibility for the patient to easily access each implant for plaque removal. Use of cemented prostheses should be limited to avoid excess cement acting as a foreign body and leading to peri-implant disease. The crown margins should be supramucosal, and the connection should be precise to avoid a gap between the implant and the suprastructure. Every implant system is characterised by a specific design, surface texture and connection type. These features may influence peri-implantitis development and progression, and the clinician should consider the risk of infection when selecting an implant. The soft-tissue conditions around the implant, the width of keratinised mucosa, and the phenotype and thickness of the mucosa are also considered major risk indicators, as the presence of any mucosal defect around an implant can increase plaque accumulation and result in tissue inflammation. The pathogenicity of the microbiota around an implant is primarily dependent on pocket depth. Deep pockets around implants should be avoided and, if present, closely monitored and/or reduced. Proximity to natural teeth presenting endodontic and/or periodontal lesions may result in implant contamination, but the influence of the type of edentulism on perio-pathogen presence is still unclear. These local conditions around an implant have a clear influence on peri-implant diseases development and progression, but there is still only limited evidence regarding their role as true risk indicators.

Experimental investigation into surface texture effect on journal bearings performance

Abstract Hydrodynamic sliding bearings are designed to operate under fully flooded conditions to enable adequate film formation. In actual operating conditions, journal bearings could operate in a mixed or even boundary lubrication regime, for example, during the start-up/shut-down period. To prevent bearing destruction, a specific surface texture can be created on the sliding zones. One of the roles of surface irregularities is to maintain a certain amount of oil in the case of its shortage. The aim of this study was to identify the characteristic parameters, such as the sliding velocity, Hersey number, and friction torque or friction coefficient, when the transition of lubrication regimes occurs for different journal bearing types. The study demonstrates the results achieved in experimental investigations conducted on journal bearings, with the oil pockets on the journal surface mating with the smooth bearing and with the texture on the bearing surface co-acting with a standard smooth journal. The obtained results were also compared with the tested effects of the classical, smoothly finished journal bearing. It was found that, during shut-down, the textured journal bearings remained in hydrodynamic lubrication for longer and moved to mixed lubrication at lower speeds compared to the smooth journal bearing.

Effect of Mn on Co/HMS-Mn and Co/SiO2-Mn catalysts for the Fischer-Tropsch reaction

The structural changes of cobalt deposited on SiO2 and Hexagonal Mesoporous Silica (HMS) supports were studied when Mn was used as a promoter and added to the catalyst during the synthesis of the supports by the sol-gel method. This synthetic method was used to promote the contact between the highly dispersed Mn in the supports and the Co added by incipient impregnation. The characterization results reveal that the presence of Mn promoted the dispersion of deposited cobalt oxide particles, causing a “wetting-like” effect of the cobalt oxide on the support surface, which led to a decrease of the average particle size of cobalt oxide from 13 to 10 nm in absence and presence of Mn respectively. The characterization results indicate that the Co2+ species react with Mn ions to form a likely Mn-Co spinel. Additionally, it was found that the promotion effects of Mn on the catalytic activity at atmospheric pressure for the Fischer-Tropsch synthetic reaction on both studied supports were significantly different because of the low metal loading used (<5 wt% of Co and 0.8 wt% of Mn) and the differences in their specific surface areas and texture. In the case of the catalysts using SiO2 as the support, the addition of Mn resulted in an enhancement of the CO consumption, whereas for the case of catalysts with HMS as the support, its presence was counterproductive, possibly because there was limited contact between the Mn and Co and because a fraction of the Mn was incorporated into the HMS framework. Furthermore, the catalytic tests at high pressure (20 bar) indicates that the catalysts were not fully selective toward hydrocarbon production, indicating that there are secondary reactions (e.g., water gas-shift reaction) due to non-reduced Co-oxide species. Additionally, at these operating conditions, the CO consumption rate increased proportionally as function of the Mn loading in the catalysts, whereas the selectivity toward olefins declined.

Microstructure and Characteristic of Biomedical Titanium Alloy Based on Picosecond Laser Micromachining

Laser micromachining has become a hotspot in recent years due to its high precision, non-contact and adjustable parameter. In this paper, TC4 titanium alloy implant samples were conducted to obtain specific surface textures through picosecond laser. The laser parameters which directly influenced the microstructure and characteristic of surface textures were optimized within the context of laser power, scanning speed and scanning number via response surface methodology. The microstructure was evaluated using scanning electron microscope (SEM) while the feature size of the surface textures was measured through surface 3D profiler. In addition, endothelial cell culture was conducted to investigate the biofunctionalization of samples with specific surface textures. It demonstrated that well-structured textures played an important role in promoting cell adhesion and proliferation for titanium alloy implants.

Effects of processing force on performance of nano-resonators produced by magnetron sputtering deposition

Magnetron sputtering is a perfect technique for processing nanomaterials for engineering and medical applications. A material can be processed with specific mechanical properties, microstructure, and surface texture by controlling the parameters of magnetron sputtering. Therefore, studies should be conducted on investigating the processing conditions on the performance of nanomaterials processed by magnetron sputtering.In this study, effects of the processing force on the surface roughness and vibration characteristics of micro/nano-resonators produced by magnetron sputtering deposition are revealed. The processing force is defined as the ratio of the sputtering power-to-the substrate's traveling velocity. By comparing the substrate's traveling velocity to the deposition rate of the sputtered particles, relations are derived for the thickness and surface roughness evolutions with the processing force. The coefficients of these relations are experimentally determined for mechanical resonators made of FeNiCr alloy. Then, the variations of the natural frequencies of these resonators with the processing force of magnetron sputtering and the deposition rate of the sputtered particles are depicted. It is demonstrated that special considerations should be given for the effects of the processing conditions and surface roughness when designing mechanical resonators produced by magnetron sputtering.

Quantification of improvement in triathlon swimming performance by textile speedsuits

To quantify swimwear-induced differences under triathlon-specific conditions, we compare the swimming performance, the metabolic cost, and the standardised passive drag of well-trained triathletes when wearing (1) five speedsuit models by different manufacturers from 2017, (2) usual swimming trunks/swimsuits (men/women), and (3) individually preferred competition trisuits. Because of the complexity of the underlying hydrodynamic and biomechanical effects, three separate experimental stages were realized, each with 6–12 well-trained short- and middle-distance triathletes (male and female, mean age 22 ± 5 years) from the German national elite or junior elite level. All measurements were conducted on the basis of real athletes’ motion in the water to correctly account for all relevant effects, including skin and muscle vibrations. First, the athletes took part in a series of 100 m short-distance tests at maximal effort in a long-course pool to quantify swim-time differences in absolute terms. Second, the subjects completed multiple submaximal 400 m tests at 95% of their individual maximal speed in a swimming flume, with their swimwear-related differences in metabolic load being explored in terms of blood lactate and heart rate. Third, the passive drag of the triathletes was measured in the flume during a towing test under standardised conditions in velocity steps of 0.2 m/s within the triathlon-relevant range of 1.1–1.7 m/s. In all three test stages, the speedsuits exhibited performance advantages over trunks/swimsuits: in the 100 m maximal test, the mean swim time with speedsuits decreased by 0.99 ± 0.30 s (≙ − 1.5%). During the 400 m submaximal flume test, the mean heart rate showed a reduction of 7 ± 2 bpm (≙ − 4.0%), while the post-exercise blood lactate accumulation decreased by 1.0 ± 0.2 mmol/L (≙ − 26.2%). Similarly, the passive drag in the towing test was lowered by 3.2 ± 1.0 W (≙ − 6.9% as for normalised power and − 5.2% as for normalised force) for the speedsuits. Wearing speedsuits instead of usual trunks/swimsuits is shown to improve the swimming performance and to reduce the metabolic cost for well-trained triathletes under triathlon-specific test conditions. The reduction in passive drag of the passively towed athlete’s body due specific speedsuit surface textures seems to be only one reason for performance advantages: the effective reduction in muscular, soft tissue, and skin vibrations at the trunk and thighs during active propulsive motion of the swimmer seems to further contribute substantially.

Study on peculiar carbon pattern formation from polymer blend thin films under electric fields

In this study, we demonstrate the formation of a peculiar carbon pattern from polyacrylonitrile/poly(methyl methacrylate) (PAN/PMMA) blend thin films under external electric fields. When a spin-coated PAN/PMMA blend thin film was exposed to an electric field, the surface of the thin film facing air layer would fluctuate due to the electrohydrodynamic instability phenomenon induced by an electrostatic force. At the same time, the interface between PAN and PMMA would also become unstable because of the difference in the dielectric constants of PAN and PMMA. The microstructure of the PAN/PMMA thin film obtained after field exposure was influenced by the combined effect of the two phenomena. Subsequent controlled thermal treatment produced an unprecedented and peculiar carbon pattern, which remained intact during carbonization. The effect of experimental parameters such as field intensity, exposure time, and film thickness on the microstructure of the polymer precursor and resulting carbon pattern was investigated. This work provides a strategy to obtain carbon structures showing specific surface texture and certain properties that have been inaccessible by any other means.

Sorption and desorption of atrazine on soils: The effect of different soil fractions

The study of atrazine (AT) sorption and desorption was carried out, employing three Brazilian soils (Typic Acrudox, Typic Argiudoll and Oxic Argiudoll), using horizons A and B, as well as their clay fractions – natural clay, clay after H2O2 treatment, clay after iron removal and after treatment to concentrate iron oxides. A contact time of 12 h was defined as adequate for sorption studies. Sorption and desorption curves were adjusted by the Freundlich equation, and satisfactory linear responses were observed, between 0.8332 and 0.9998 for the sorption process. Multiple regression analyses were performed considering the mineralogy, organic carbon content, specific surface area and texture of the soils, and the Freundlich parameter Kf. The principal influence for AT sorption was attributed to organic carbon content and physical bonding on quartz for soil samples. Positive correlation with goethite was observed for clay fractions. The Kf values for sorption (Kf(S)) obtained for soil samples were between 0.60 and 3.9, and for clay fractions were between 1.90 and 5.30, suggesting an important role of the mineral phase in the sorption of AT. Environmental risks of groundwater contamination were evaluated using the partition coefficient normalized by the soil organic carbon content (Koc), hysteresis index (HI), groundwater ubiquity score (GUS) and leachability index (LIX). Both horizons for the three soils presented leaching potential for AT based on GUS and LIX parameters.