To look for applications, search for a keyword on this page and find papers related to it. If you are scientist and want some of your publications listed here, please send us your latest papers. We will be pleased to add them here (providing they use or cite MountainsMap or a partner equivalent product). Other publications are available in French, Spanish, Polish, etc. but are not listed here. More publications: see at the bottom of the page.
For information, more than 700 publications used and/or mentionned Mountains® were published in 2023 alone.
Improving the formability of linear flow split profiles by laser annealing
NIEHUESBERND J, [...], Materialwissenschaft und Werkstofftechnik
The effect of laser annealing on the mechanical properties of severely deformed low alloy steel is discussed. Two different sets of annealing parameters were used to achieve improvements in formability. The resulting microstructures, tensile properties and hardness distributions are reviewed. Annealing at temperatures around 700 °C with very high heating and cooling rates leads to recrystallization at the surface and moderate grain growth in subsequent layers. The improvement in ductility is proven to be sufficient to prevent cracking during bending operations.
Growth defects in magnetron sputtered PVD films deposited in UHV environment
M CEKADA, [...], Vacuum, [Talymap]
The growth defects in magnetron sputtered coatings have been well studied in industrial environment. In this work, on the other hand, the emphasis is in observing the same phenomena in a lab-scale UHV environment. TiN and CrN films were deposited at a thickness of 1–2 μm. The statistical evaluation of defect density was based on stylus profilometry scans (2 mm2 area), and consequent analysis of hillock density in dependence of threshold height. Morphology of defects was observed by SEM, while on selected defects we made FIB cross-sections. In this way we were able to measure the chemical composition of individual seeds – starting points for growth defects. In contrast to expectations, there was only a relatively minor reduction of defect density by using UHV environment.
[PDF] Metal-Oxide Decorated Multilayered Three-Dimensional (3D) Porous Carbon Thin Films for Supercapacitor Electrodes
K MONDAL, R KUMAR, A SHARMA, I&EC Research, [PicoImage]
We demonstrate an easy, scalable, and two-step
synthesis of macroporous carbon, carbon/TiO2 (cTiO2), carbon/MnO2 (cMnO2), and carbon/TiO2/MnO2 (cTiO2/MnO2) composite thin films for energy storage applications. The direct synthesis of the hybrid films was achieved by spin
coating, followed by carbonization. The unique multilayered three-dimensional (3D) pore structure of the film permits the synthesis of carbon/TiO2/MnO2 nanocomposites with enhanced metal-oxide nanoparticle loading up to 50 wt %.
The as-synthesized porous carbon thin films were tested for their supercapacitor activity and a maximum specific capacitance ∼44 F g−1 was achieved with a film thickness of 350 nm. The as-prepared cTiO2, cMnO2, and cTiO2/MnO2 electrodes exhibit high specific capacitances of 178, 237, and
297 F g−1, respectively, at 5 mV s−1, because of their unique properties with impregnated nanoparticles, and direct fabrication on conductive substrates. This simple scalable coating technique is compatible with the high-speed roll-to-roll manufacturing processes and easily generalized for other carbon/metal oxide composites. We demonstrate an easy, scalable, two-step synthesis method similar to the roll-to-roll process for the synthesis of multilayered of macroporous carbon, carbon/TiO2 (cTiO2), carbon/MnO2 (cMnO2), and carbon/TiO2/MnO2 (cTiO2/MnO2) composite thin films for energy storage applications.
PVDF/TiO2 nanocomposites prepared by solution blow spinning: Surface properties and their relation with S. Mutans adhesion
J GONZALEZ-BENITO, [...], Polymer Testing, [MountainsMap]
Thermoplastic nanocomposite materials with potential bactericide properties were prepared and their surface properties and adhesion to Streptococcus mutans, S. mutans, were characterized. Solution blow spinning was successfully used to prepare films with a fiber-like structure on the surface of nanocomposites based on Polyvinylidene fluoride, PVDF, filled with well dispersed TiO2 nanoparticles. PVDF/TiO2 nanocomposites were prepared varying the nanoparticles content (0%, 1%, 2%, 5% and 10% by weight). In order to understand the influence of the presence of TiO2 nanoparticles and the final surface properties on the adhesion of S. mutans to the materials, a deep characterization was carried out focusing on the morphology, roughness, surface free energy from contact angle measurements and cell adhesion by single cell force spectroscopy. It was observed that the uniform dispersion of the nanofiller arose from nanoparticles embedded in the polymer when fibers were created during the blow spinning process. TiO2 content influenced the topography of the films probably due to a direct effect on the solvent evaporation rate. Although this factor greatly conditioned the roughness of the samples and therefore the surface free energy, S. mutant adhesion on the substrates under study was concluded to be more dependent on the specific interactions with the surface polar groups of the material.
Corrosion inhibition and surface analysis of amines on mild steel in chloride medium
K XHANARI, [...], Chem Papers, [Talymap]
In this study, the corrosion inhibition effectiveness of eight amines, i.e. 2-ethylhexyl amine, aniline, benzylamine, butylamine, ethylamine, isopropylamine, octylamine, and triethanolamine, on C15 grade mild steel in 3 wt% NaCl solution is reported. The corrosion inhibition performance of the amines was studied using immersion tests at 25 and 70°C, with and without the addition of KI as a possible intensifier. Among the inhibitors tested at 0.1 wt% concentration, the lowest corrosion rates were obtained for specimens immersed in solutions containing 2-ethylhexyl amine at 25°C and triethanolamine at 70°C. The highest inhibition effectiveness at 25°C among all amines tested was obtained for 1.0 wt% butylamine with the addition of 0.5 wt% KI, while at 70°C the lowest corrosion rate was obtained for specimens inhibited with 1.0 wt% isopropylamine. Surface analysis was subsequently performed on specimens inhibited by the most effective inhibitors. Adsorption of the selected amines on the C15 grade mild steel surface was confirmed by ATR-FTIR. 3D-profilometry showed a reduction in the surface roughness (less corroded) for the specimens inhibited with these inhibitors compared to the non-inhibited specimens. Contact angle measurements showed that all of the tested specimens were hydrophilic.
Inflammatory cell response to ultra-thin amorphous and crystalline hydroxyapatite surfaces
L RYDEN, [...], J Mat Sci, [MountainsMap]
It has been suggested that surface modification with a thin hydroxyapatite (HA) coating enhances the osseointegration of titanium implants. However, there is insufficient information about the biological processes involved in the HA-induced response. This study aimed to investigate the inflammatory cell response to titanium implants with either amorphous or crystalline thin HA. Human mononuclear cells were cultured on titanium discs with a machined surface or with a thin, 0.1 μm, amorphous or crystalline HA coating. Cells were cultured for 24 and 96 h, with and without lipopolysaccharide (LPS) stimulation. The surfaces were characterized with respect to chemistry, phase composition, wettability and topography. Biological analyses included the percentage of implant-adherent cells and the secretion of pro-inflammatory cytokine (TNF-α) and growth factors (BMP-2 and TGF-β1). Crystalline HA revealed a smooth surface, whereas the amorphous HA displayed a porous structure, at nano-scale, and a hydrophobic surface. Higher TNF-α secretion and a higher ratio of adherent cells were demonstrated for the amorphous HA compared with the crystalline HA. TGF-β1 secretion was detected in all groups, but without any difference. No BMP-2 secretion was detected in any of the groups. The addition of LPS resulted in a significant increase in TNF-α in all groups, whereas TGF-β1 was not affected. Taken together, the results show that thin HA coatings with similar micro-roughness but a different phase composition, nano-scale roughness and wettability are associated with different monocyte responses. In the absence of strong inflammatory stimuli, crystalline hydroxyapatite elicits a lower inflammatory response compared with amorphous hydroxyapatite.
Transient pulse test and morphological analysis of single rock fractures
Y ZHAO, [...], Int J Rock Mech and Mining Sci, [Talymap]
Transient pulse tests were performed on single rock fractures at different confining pressures. A new data analysis method based on polynomial fitting was introduced to investigate the relationship between flow velocity and hydraulic gradient. 3D laser scanning was used to quantify the morphological changes of the fracture surface after the transient pulse test or under the hydro-mechanical coupling effect. The results show that the flow velocity versus hydraulic gradient data gradient shows a nonlinear relationship at very low hydraulic, possibly due to strong solid-water interaction, but becomes approximately linear after the hydraulic gradient is high enough. The permeability of a single fracture is sensitive to the confining pressure. As the confining pressure increases, the permeability first remarkably decreases when the confining pressure is lower than a certain value and then decreases at a much lower speed when the confining pressure is higher than that value. Both mechanical and hydraulic apertures decrease at a decreasing rate with the increase in confining pressure. The effect of fracture roughness on the permeability is related to the magnitude of the confining pressure. Rougher fractures have lower permeability at low confining pressures; but the opposite can be true when the confining pressure is high enough. Roughness is no longer critical to permeability when the confining pressure is over a certain value.
Erbium, Chromium:Yttrium-Scandium-Gallium-Garnet Laser Effectively Ablates Single-Species Biofilms on Titanium Disks Without Detectable Surface Damage
J M STREVER, [...], J Periodontology, [Talymap]
Increasing evidence implicates biofilms, consisting of species such as Porphyromonas gingivalis (Pg), in the etiology of peri-implantitis. Multiple approaches to ablate biofilms on failing implants have been proposed and include use of lasers, most recently the erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser. The purpose of this study is to establish an in vitro single-species biofilm model on implant surfaces and determine power settings of the Er,Cr:YSGG laser that remove biofilm without causing physical damage to disks. Single-species biofilms consisting of Pg strain 381 were grown on titanium disks, including: 1) sandblasted, large-grit, acid-etched (SLA); 2) calcium phosphate nano-coated (CaP); 3) anodized; or 4) machined surfaces. Power settings from 0 to 1.5 W using an Er,Cr:YSGG laser equipped with radial firing tip were used. Biofilm formation/removal was quantitated using confocal and scanning electron microscopy. Surface changes in temperature, microroughness, and water contact angle were analyzed.
The surface topography of a metallic femoral head and its influence on the wear mechanism of a polymeric acetabulum
M NIEMCZEWSKA-WOJCIK, W PIEKOSZEWSKI, {Arc Civil Mech Eng, [TalyMap]
The wear mechanisms of friction components depend on conditions of articulation, material properties and surface topography of the co-acting parts. Therefore, it is important to examine these determinants in order to improve the durability of a friction pair. With the view of securing the longer life of articulating surfaces, a metallic femoral head used in conjunction with a polymeric acetabulum was subject to research. The components of the friction pair were prepared in accordance with the standard specification ASTM F2033-12. From the precision machining process of metallic femoral heads, two different kinds of surface topography (defined by Ra parameter: Ra(A) < Ra(B)) were obtained. The tribological research was performed with a testing machine simulating the kinematic movements and the working conditions of a natural joint (friction pair: ball-and-socket) in the Ringer's solution. The measurements of the surface topography (machined and worn surfaces) were conducted using the following measuring devices: coordinate measuring machine, white light interference microscopy and scanning electron microscopy. Based on the analysis results, the influence of the surface topography of the metallic ball upon tribological characteristics was determined. The wear mechanisms of the polymeric socket resulted from a number of phenomena, including plastic deformation, abrasive wear, fatigue and adhesion.
Magnetoresistance of nanocomposite copper/carbon thin films
A ARMAN, [...], J Mat Sci, [MountainsMap]
Nanocomposite thin films made of partially oxidized Cu nanoparticles embedded into hydrogenated amorphous carbon, with different thicknesses and Cu/C ratio, were prepared by means of radio frequency plasma enhanced chemical vapor deposition and radio frequency sputtering using acetylene gas and copper target. The surface roughness was investigated using atomic force microscopy, revealing the fractal geometry of the Cu/carbon thin films at the nanoscale with fractal dimensions around 2.7. In addition, the electrical properties of these films and their dependence on the application of low magnetic fields were explored at room temperature. It was found that when the Cu nanoparticles are separated by gaps, the electrical conduction is governed by tunneling effects. In these conditions, the samples exhibit negative magnetoresistance values, displaying steps in the dependences on the magnetic field. These properties suggest the potential use of these films as magnetic sensors in spintronics.
The influence of drawing speed on surface topography of high carbon steel wires
M SULIGA, [Talymap]
In this work the influence of the drawing speed on surface topography of high carbon steel wires has been assessed.
The drawing process of f 5,5 mm wire rod to the final wire of f 1,7 mm was conducted in 12 passes by means of a modern Koch multi-die drawing machine. The drawing speeds in the last passes were: 5, 10, 15, 20 and 25 m/s. For
final wires f 1,7 mm the three-dimensional analysis of the wire surface topography investigation was determined. It has been proved that the wire topography in the drawing process is characterized by a random anisotropy and the
amount of directing the geometrical structure of the surface depends on the drawing speed.
A new high-resolution 3-D quantitative method for identifying bone surface modifications with implications for the Early Stone Age archaeological record
M C PANTE, [...], J Human Evolution, [MountainsMap]
Bone surface modifications have become important indicators of hominin behavior and ecology at prehistoric archaeological sites. However, the method by which we identify and interpret these marks remains largely unchanged despite decades of research, relying on qualitative criteria and lacking standardization between analysts. Recently, zooarchaeologists have begun using new technologies capable of capturing 3-D data from bone surface modifications to advance our knowledge of these informative traces. However, an important step in this research has been overlooked and after years of work, we lack both a universal and replicable protocol and an understanding of the precision of these techniques. Here we propose a new standard for identifying bone surface modifications using high-resolution 3-D data and offer a systematic and replicable approach for researchers to follow. Data were collected with a white-light non-contact confocal profilometer and analyzed with Digital Surf's Mountains® software. Our data show that when methods are standardized, results between researchers are statistically indistinguishable. Multivariate analyses using the measured parameters allow discrimination between stone tool cut marks and mammalian carnivore tooth marks with 97.5% accuracy. Application of this method to fossil specimens resulted in 100% correspondence with identifications made by an experienced analyst using macroscopic observations of qualitative features of bone surface modifications. High-resolution 3-D analyses of bone surface modifications have great potential to improve the reliability and accuracy of taphonomic research, but only if our methods are replicable and precise.
Peri-implantitis cleaning instrumentation influences the integrity of photoactive nanocoatings
F KISTER, [...], Dental Mat, [MountainsMap]
Anatase-coated titanium discs were treated with diamond burs, polishers, plastic and metal hand instruments, air scaler and air flow devices. The pressure exerted through instrumentation was measured online. Surface topography was evaluated through scanning electron microscopy and contact profilometry, surface function through hydrophilization capacity upon UV-A activation. Treatment with diamond burs and instruments with metal tips resulted in an increase of roughness. Use of silicone polishers led to smoothening, which was more pronounced on the anatase surface. Plastic instruments, the air abrasive system and rubber cups left the surfaces intact. Functionality was partially lost on surfaces subjected to hand instruments and completely lost upon diamond burs and silicone polishers. The integrity of functional nanocoatings depends on the applied instrumentation. Air flow device, rubber cup with polishing paste and plastic tipped instruments prevent damage on these nanosurfaces and may be preferably used when decontaminating anatase and other nanocoatings in a clinical setting.
Atomic-scale characterization of subsurface damage and structural changes of single-crystal silicon carbide subjected to electrical discharge machining
T H TAN, J YAN, Acta Materialia, [Talymap]
Single-crystal silicon carbide (SiC) is an important semiconductor material used in power electronics. Due to its high hardness and brittleness, SiC is very difficult to machine using mechanical methods. Electrical discharge machining (EDM) has recently garnered extensive research interest as a potential machining method for SiC. However, this technique induces severe subsurface damage on the workpiece. To date, mechanisms leading to EDM-induced subsurface damage in SiC have not been clarified. This study aims to investigate the atomic-scale subsurface damage in SiC induced by EDM using Raman spectroscopy and transmission electron microscopy (TEM). In cross-sectional TEM observations, three regions of subsurface damage were identified, namely, the re-solidified layers, heat-affected zones, and microcracks. It was found that SiC decomposed into silicon and carbon in the re-solidified layers, and the degree of decomposition depended on the discharge energy and workpiece polarity. The re-solidified layer was a mixture of crystalline/amorphous silicon, crystalline/amorphous carbon, and nano-crystalline SiC. The presence of an extremely thin graphite layer was observed in the re-solidified layer. The heat-affected zone remained crystalline but showed a different crystal structure distinct from that of the bulk.
Dry cutting effect in turning of a duplex stainless steel as a key factor in clean production
G M KROLCZYK, [...], J Cleaner Prod, [MountainsMap]
The machining of duplex stainless steel usually involves the application of cutting fluids, which consequently leads to negative ecologic, environmental and health impacts. Therefore, the purpose of the study was to identify the optimal machining strategy and conditions, which will lead to the reduction of pollution generated by cooling/lubricating with coolants and emulsions, as well as the reduction of energy consumption during manufacturing process. The research program included longitudinal turning tests with the application of three different carbide tools. The experiments were carried out in dry and cooling/lubricating conditions, and involved the measurements of surface roughness, cutting force components and tool life. The results presented demonstrate that dry turning with the appropriately selected cutting tool grade and machining conditions induce almost three-fold growth of tool life in comparison to that obtained during cutting with fluids. The results show that the cutting tool life of duplex stainless steel depends on the following problems: difficult chip control and excessive thermal and mechanical loads of the cutting tool. It was also concluded that a rational solution in terms of energy consumption is machining without cooling, which involves combination of high cutting speed with low feed rate.
Electrochemical treatment of aluminium alloy 7075 in aqueous solutions of imidazolium phosphonate and phosphate ionic liquids and scratch resistance of the resultant materials
M ARRES, [...], Tribology Int, [Talymap]
The abilitiy of 1-ethyl-3-methylimidazolium ethylphosphonate ([ImPhosphonate]) and 1-ethyl-3-methylimidazolium diethylphosphate ([ImPhosphate]) ionic liquids (ILs) to interact with anodized Al7075 T6 aluminium alloy has been studied via electrochemical techniques under different applied potentials, inside and outside the passivation regions. SEM, EDX and XPS analysis have been used to study the composition of the surface coatings. The abrasion resistance after treatment with the ILs has been studied by scratch tests under progressive load, and compared with the performance of the unprotected material and the anodized alloy. While conventional anodization only improves the abrasion resistance of Al7075 in a 30%, the maximum reduction of the penetration depth, 86% with respect to Al7075 and 79% with respect to the anodized alloy, is obtained for the material treated with [ImPhosphonate] at 1 V, in the passivation region. Under these conditions, a phosphorus-containing alumina layer is formed. Applied voltages outside the passivation region for each IL activate the dissolution of the alumina layer and reduce abrasion resistance, not only with respect to the anodized material, but also with respect to the unprotected alloy.
The emulsifying and tribological properties of modified graphene oxide in oil-in-water emulsion
Y WU, [...], Tribology Int, 105, 304-316, [LeicaMap]
Graphene oxide (GO) was asymmetric chemically modified with myristyltrimethylammonium bromide (TTAB) to get modified graphene oxide (MGO). This MGO was used as an emulsifier and additive in oil-in-water emulsion. The emulsifying tests showed MGO greatly improved the stability of base emulsion and decreased its droplets size. Tribological test results showed that under the boundary lubrication condition with MGO-emulsion, the friction coefficient (COF) and the wear rate of the steel ball were decreased by about 18% and 48% respectively, comparing with base emulsion lubrication. The tribological mechanism of MGO-emulsion could be explained by the strong film-forming ability on the metal surface; the good lubricity of its small droplets; the formed adsorption film, transfer film and tribofilm between the contact surfaces.
Improvement of form accuracy and surface integrity of Si-HDPE hybrid micro-lens arrays in press molding
A R ABDUL MANAF, J YAN, Prec Eng, [Talymap]
Press molding of silicon (Si)/high-density polyethylene (HDPE) composite is an important technology for producing thin hybrid infrared (IR) optics with microstructures. In this research, Si-HDPE hybrid micro-lens arrays were press molded under various conditions, and the form accuracy and surface integrity of the molded lenses were evaluated. Air trapping occurs inside the micro-lens cavities during molding in a non-vacuum environment, which leads to severe surface defects. To investigate the air trapping phenomenon, a new in-situ observation system was developed which enables real-time direct observation of the molding process. From the in-situ observations, it was found that air traps were formed among the HDPE pellets during melting, and an increase in the pressing force will increase the pressure of the trapped air, forming trenches on the lens surface. The trapped air also impacts the mold coating, causing trench formation on the coating surface. To minimize air trapping, the molding temperature, and pressing force must be strictly controlled. By performing press molding in a vacuum environment, trench formation was completely eliminated. Moreover, polymer shrinkage compensation was performed to improve the lens form accuracy.
Characterization and performance study of phase inversed Sulfonated Poly Ether Ether Ketone – Silico tungstic composite membrane as an electrolyte for microbial fuel cell applications
P NARAYANASWAMY, S DHAMALINGAM, Renewable Energy, [Talymap]
Hybrid composite membranes possess the desired properties than that of the pristine polymeric membranes for fuel cell applications. Phase inversion method was used to entrap silicotungstic acid (STA) particles in Sulfonated Poly Ether Ether Ketone (SPEEK) membranes as a source of protons having a high protonic conductivity at room temperature (0.02–0.1 S/cm). The physico-chemical properties of the hybrid membranes were characterized by SEM-EDX, line scanning, 3D non-contact profilometer, FTIR and XRD techniques. These membranes showed better ion exchange, proton conductivity values and were tested in single chamber microbial fuel cell (SCMFC). In addition, these membranes show decreased oxygen crossover and transport of cations other than protons. Among the various weight percentage (2.5%, 5%, 7.5% and 10%) of STA prepared composite membranes, 7.5% STA + SPEEK showed the highest power density of 207 mWm−2 compared to that of commercial Nafion 117 (47 mWm−2) in the same setup of SCMFC. Overall, the composite membranes proved to be excellent candidates as electrolytes for Microbial Fuel Cell (MFC) applications.
Comment on: ‘‘The effect of pressure on morphological features and quality of synthesized graphene’’
S SOLAYMANI, A GHADERI, S KULESZA, M BRAMOWICZ, Research Chem Intermediates, [MountainsMap]
In their recent article, Alipour et al. (Res Chem Intermed, 1. doi:10.1007/s11164-016-2594-8) studied the effect of pressure on the morphological characteristics and quality of synthesized graphene from SEM data. Here, the basics of fractal calculations and depth histogram will be explained to avoid such egregious mistakes between using AFM, SEM and stereo SEM images by authors.
Colorimetry as Quality Control Tool for Individual Inkjet-Printed Pediatric Formulations
H WICKSTRÖM, J O NYMAN, [...], AAPS PharmSciTech, [MountainsMap]
Printing technologies were recently introduced to the pharmaceutical field for manufacturing of drug delivery systems. Printing allows on demand manufacturing of flexible pharmaceutical doses in a personalized manner, which is critical for a successful and safe treatment of patient populations with specific needs, such as children and the elderly, and patients facing multimorbidity. Printing of pharmaceuticals as technique generates new demands on the quality control procedures. For example, rapid quality control is needed as the printing can be done on demand and at the point of care. This study evaluated the potential use of a handheld colorimetry device for quality control of printed doses of vitamin Bs on edible rice and sugar substrates. The structural features of the substrates with and without ink were also compared. A multicomponent ink formulation with vitamin B1, B2, B3, and B6 was developed. Doses (4 cm2) were prepared by applying 1–10 layers of yellow ink onto the white substrates using thermal inkjet technology. The colorimetric method was seen to be viable in detecting doses up to the 5th and 6th printed layers until color saturation of the yellow color parameter (b*) was observed on the substrates. Liquid chromatography mass spectrometry was used as a reference method for the colorimetry measurements plotted against the number of printed layers. It was concluded that colorimetry could be used as a quality control tool for detection of different doses. However, optimization of the color addition needs to be done to avoid color saturation within the planned dose interval.
Influence of mechanical properties, anisotropy, surface roughness and porosity of brick on FRP debonding force
E SASSONI, S ANDREOTTI, [...], Composites Eng, [LeicaMap]
This paper aims at evaluating how the FRP/brick debonding force is influenced by brick mechanical properties (compressive, tensile and flexural strength) and physical-microstructural properties (surface roughness, porosity, pore size distribution, rate of water capillary suction). The depth of epoxy resin penetration into bricks and the thickness of brick layer detached at the end of bond test were also determined, in order to investigate the role of resin penetration into the brick on the FRP performance. All the tests were carried out on different brick surfaces (namely “bed” and “face”), to account for possible brick anisotropy. The results of the study point out that brick mechanical properties alone are not sufficient to accurately predict the maximum debonding force, but a better estimation can be achieved taking into account also brick surface roughness and resin penetration depth. If brick anisotropy is not considered, in some cases a remarkable overestimation of the maximum debonding force may be found.
3-D surface stereometry studies of sputtered TiN thin films obtained at different substrate temperatures
S STACH, W SAPOTA, [...], J Mat Sci, [MountainsMap]
Nanostructured glass-supported thin films of titanium nitride (TiN) were prepared by reactive magnetron sputtering at different substrate temperatures (from 25 to 400 °C). The surface topography of such films was examined by atomic force microscopy (AFM). The obtained 3-D AFM images was divided into motifs of significant peaks and pits using MountainsMap® Premium software, which uses the watershed segmentation algorithm. In the motif analysis, parameters consistent with ISO 25178-2: 2012 and that characterize essential characteristics of the segmented motifs in terms of surface dimensions, volume, curvature, shape, structure, etc. were calculated, and the highest and lowest points of motifs were localized. This study allowed us to perform a quantitative correlation between synthetic conditions of TiN thin films and their 3-D micro-textured surface properties. Concretely, we found a non-monotonic dependence of the surface morphology properties of the thin films on the substrate temperature during the sample deposition, obtaining the most regular surface at a substrate temperature of 250 °C and the most irregular topography at the substrate temperature of 400 °C.
On direct estimation of hardening exponent in crystal plasticity from the spherical indentation test
H PETRYK, S STUPKIEWICZ, S KUCHARSKI, Int J Solids and Structures, [HommelMap]
A novel methodology is proposed for estimating the strain hardening exponent of a metal single crystal directly from the spherical indentation test, without the need of solving the relevant inverse problem. The attention is focused on anisotropic piling-up and sinking-in that occur simultaneously in different directions, in contrast to the standard case of axial symmetry for isotropic materials. To correlate surface topography parameters with the value of material hardening exponent, a finite-element study of spherical indentation has been performed within a selected penetration depth range using a finite-strain crystal plasticity model. It is shown how the power-law hardening exponent can be estimated from the measured pile-up/sink-in pattern around the residual impression after indentation in a (001)-oriented fcc single crystal of a small initial yield stress. For this purpose, a new parameter of surface topography is defined as the normalized material volume displaced around the nominal contact zone, calculated by integration of the local residual height (positive or negative) over a centered circular ring. That indicator can be easily determined from an experimental topography map available in a digital form. Comparison is made with the estimates based on measurements of the contact area and the slope of the load–penetration depth curve in logarithmic coordinates. The proposed methodology is extended to estimation of the hardening exponent simultaneously with the initial yield stress when the latter is not negligible. Experimental verification for a Cu single crystal leads to promising conclusions.
Effect of relative humidity and temperature on the tribology of multilayer micro/nanocrystalline CVD diamond coatings
M SHABANI, C S ABREU, [...], Diamond and Related Materials, [SensoMap]
The tribological behavior of tenfold micro/nanocrystalline CVD diamond multilayers is here investigated in self–mated configuration using ball-on-plate reciprocating wear testing. The effects of relative humidity (RH) and temperature (T) on friction and wear coefficients are assessed. The strongest effect of humidity was found on the value of the critical load (no delamination) that triples from 40 N at 10%RH to 120 N at 90%RH. Evaluation of the wear coefficients of the plates was only possible with the use of 3D optical profilometry. A valley-shaped evolution is observed for the wear coefficient of the plates, within the 10% to 90% RH range, with a minimum of about 1.7x10-7 mm3N-1.m-1, indicative of a mild wear regime, whereas the balls have lower values in the very mild wear regime of k ~ 10-8 mm3N-1.m-1. The clearest difference between the RH and temperature experiments is observed for the critical loads, limited to the range 40-55 N at 50-100°C, while at room temperature a value of 120 N was reached. However, the critical loads at high temperature are similar to those attained under dry conditions (≤ 25% RH) highlighting the absence of water as the load bearing medium.
Topography evolution and friction coefficient of gray and nodular cast irons with duplex plasma nitrided + DLC coating
R OSS GIACOMELLI, D BERTI SALVARO, [...], Surface and Coatings Tech, [MountainsMap]
In the present study, the main critical factors affecting the production of high tribological performance coatings on substrates containing near surface graphite were evaluated. Plasma nitriding followed by deposition of a hydrogenated diamond like carbon film (a-C:H) on gray cast iron (GCI) and nodular cast iron (NCI) substrates were carried out using a single thermal cycle. The surface topography evolution was evaluated via Scanning Electron Microscopy (SEM) and White Light Interferometry (WLI). As expected, there is a huge variation in surface topography and morphology according to graphite shape. An intense modification on the topography of GCI was observed, in particular wedges formation after nitriding. In order to enable a more in-depth understanding, the surface evolution after plasma nitriding of cast irons was carefully investigated and discussed in light of EDS linescans and XRD. Micro Raman spectroscopy and TEM analysis indicated that the DLC has an average amount of clustered sp2 bonding in the structure. Additionally, the tribological performance of multifunctional coatings was evaluated via durability tests in ambient air, which revealed friction coefficients as low as 0.06 during steady-state lubrication regime for gray cast iron substrates, whereas the values were of 0.14 for nodular cast iron substrates. Crucial differences were found between friction coefficient behaviours: the GCI presented lubricious tribolayers covering most part of wear track whereas NCI presented topographic factors inhibiting tribolayers formation, a key factor that might explain the friction coefficient variation.
Binderless Solution Processed Zn Doped Co3O4 Film on FTO for Rapid and Selective Non-enzymatic Glucose Detection
M CHOWDHURY, F CUMMINGS, M KEBEDE, V FESTER, Electroanalysis, [PicoImage]
A simple solution based deposition process has been used to fabricate Zn doped Co3O4 electrode as an electrocatalyst for non-enzymatic oxidation of glucose. XRD, HRTEM, SEM, EELS, AFM, EIS was used to characterise the electrode. The addition of Zn as dopant on Co3O4 resulted in enhanced electrochemical performance of Zn:Co3O4 material compared to pristine Co3O4 due to increased charge transferability. The as prepared electrode showed fast response (< 7 s) time, good sensitivity (193 μA mM−1 cm−2) in the linear range of 5 μM–0.62 mM, good selectivity towards glucose at a relatively lower applied potential of +0.52 V in 0.1 M NaOH solution. A detection limit of ~2 μM was measured for the Zn:Co3O4 electrode. The applied fabrication method resulted in good inter and intra electrode reproducibility as was shown by the lower relative standard deviation values (R.S.D). The electrode retained 70 % of initial current response after 30 days. Although the as prepared Zn:Co3O4 electrodes did not result in highest reported sensitivity, and lowest limit of detection; the ease of fabrication and scalability of production, good inter and intra electrode reproducibility makes it a potential candidate for commercial application as glucose sensor.
Proliferation, behavior, and differentiation of osteoblasts on surfaces of different microroughness
O ANDRUCKOV, R HUBER, [...], Dental Metrials, [SensoMap]
Titanium surface roughness is recognized as an important parameter influencing osseointegration. However, studies concerning the effect of well-defined surface topographies of titanium surfaces on osteoblasts have been limited in scope. In the present study we have investigated how Ti surfaces of different micrometer-scale roughness influence proliferation, migration, and differentiation of osteoblasts in-vitro.
Titanium replicas with surface roughnesses (Ra) of approximately 0, 1, 2, and 4 μm were produced and MG-63 osteoblasts were cultured on these surfaces for up to 5 days. The effect of surface micrometer-scale roughness on proliferation, migration in time-lapse microscopy experiments, as well as the expression of alkaline phosphatase, osteocalcin, vascular-endothelial growth factor (VEGF), osteoprotegerin (OPG), and receptor activator of nuclear factor kappa-B ligand (RANKL) were investigated.
Design of carbon nanofiber embedded conducting epoxy resin
S GANTAYAT, N SARKAR, D ROUT, S K SWAIN, Mat Chem and Physics, [PicoImage]
Acid treated carbon nanofiber (t-CNF) reinforced epoxy nanocomposites were fabricated by hand lay-up method with various wt % of t-CNF loadings. Pristine or unmodified carbon nano fibers (u-CNFs) were made compatible with epoxy matrix by means of mixed acid treatment. Fabricated nanocomposites were characterized with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) study, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and atomic force microscopy (AFM). Mechanical and thermal properties of the nanocomposites were measured as a function of t-CNF content. Effect of acid treated CNFs on to the mechanical properties of epoxy nanocomposites was justified by comparing the mechanical properties of epoxy/t-CNF and epoxy/u-CNF nanocomposites with same loading level. The electrical conductivity was achieved by epoxy resin with a threshold at 1 wt % of t-CNF. Substantial improvement in thermal, mechanical and electrical properties of the synthesized epoxy/t-CNF nanocomposites may be suitable for fabricating electronic devices.
MQL with water in cylindrical plunge grinding of hardened steels using CBN wheels, with and without wheel cleaning by compressed air
R SOUZA RUZZI, R MELLO BELENTANI, [...], Int J Adv Manuf Tech, [Talymap]
Minimum quantity of lubricant (MQL) in grinding is an alternative for reducing abundant fluid flow and both environmental and health hazards when compared with conventional fluid application. In spite of the fact that MQL is considered an innovative cost-effective and environmentally friendly technique, when used in grinding its inadequate application can increase cutting temperature and wheel clogging, worsening surface roughness, and increasing geometric and dimensional errors. The present study aims to evaluate improvements in MQL in grinding using MQL + water (1:1, 1:3, and 1:5 parts of oil per parts of water), when compared to MQL without water and conventional cooling-lubrication technique. Wheel cleaning by compressed air was also tested, aimed for unclogging of the wheel pores. The tests were performed in a plunge cylindrical grinder with CBN wheel and workpieces of AISI 4340 for different feed rates. The ground workpieces were analyzed with respect to the surface roughness, roundness errors, microhardness, and microscopic changes. In addition, tangential cutting force and diametric wheel wear were investigated. The results observed for the MQL plus water in the proportion of 1:5, with wheel cleaning system (at 30° inclination angle of the air nozzle) were the best, when compared to MQL without water, and close to the conventional flood coolant, implying that this technique is a potential alternative for cooling-lubrication when applied properly.
A new approach on morphological features of synthesized graphene using the LPCVD technique applicable for fuel cell membrane
R ALIPOUR, A JAFARI, A SALAR ELAHI, M GHORANNEVISS, Int J Hydrogen Energy, [MountainsMap]
The one-atom-thick materials such as graphene, once thought to be impermeable, allow protons to pass through them. The result will be more efficient fuel cells and the simplification of the heretofore difficult process of separating hydrogen gas for use as fuel in fuel cells. In this research, a large scale graphene were synthesized by Low Pressure Chemical Vapor Deposition (LPCVD) technique. The effects of temperature growth on morphological features of the synthesized graphene on Cu foils were studied, using only Scanning Electron Microscopy (SEM) analysis. Raman spectrum was used to quantify defects and characteristics of synthesized graphene. Three peaks at ∼1350, ∼1580 and ∼2750 cm−1 related to the D band, G band and 2D band are shown from Raman analysis. The Mountains Map Premium software and the Gwyddion software were used for investigation on morphological features of synthesized graphene samples. The results show that the defects intensity in graphene decreased and the quality of synthesized graphene increased with increasing growth temperature. The grain size and producing the large area of graphene decreased and increased, respectively with the rise of temperature. At all temperatures growth, the multilayer graphene are grown on Cu substrates. The results of the motifs analysis shows that the synthesized graphene layers are made of oblong grains. On the surface of synthesized samples at 800 and 850 °C were dominant of valleys. Also, on the surface of synthesized samples at 900 and 1000 °C, the peaks were dominant. Thus, the surfaces of all synthesized samples were spiky and isotropic and have an oriented or periodical structure. All results of this work represent that the defects intensity, quality, grain size and uniformity of synthesized graphene could be controlled by only changing the temperature and keeping the other effective parameters constant.
Skin friction related behaviour of artificial turf systems
S P TAY, P FLEMING, X HU, S FORRESTER, J Sports Sci, [Talymap]
The occurrence of skin friction related injuries is an issue for artificial turf sports pitches and remains a barrier to their acceptance. The purpose of this study was to evaluate the current industry standard Securisport® Sports Surface Tester that measures skin surface related frictional behaviour of artificial turf. Little research has been published about the device and its efficacy, despite its widespread use as a standard FIFA test instrument. To achieve a range of frictional behaviours, several “third generation” (3G) carpet and infill combinations were investigated; friction time profiles throughout the Securisport rotations were assessed in combination with independent measurements of skin roughness before and after friction testing via 3D surface scanning. The results indicated that carpets without infill had greatest friction (coefficients of friction 0.97–1.20) while those completely filled with sand or rubber had similar and lower values independent of carpet type (coefficient of friction (COF) ≈0.57). Surface roughness of a silicone skin (s-skin) decreased after friction testing, with the largest change on sand infilled surfaces, indicating an “abrasive” polishing effect. The combined data show that the s-skin is damaged in a surface-specific manner, thus the Securisport COF values appear to be a poor measure of the potential for skin abrasion. It is proposed that the change in s-skin roughness improves assessment of the potential for skin damage when players slide on artificial turf.
Aggregation and conformational change of mushroom (Agaricus bisporus) polyphenoloxidase subjected to thermal treatment
ZHOU L, LIU W, [...], Food Chemistry, 214, [PicoImage]
This study investigated changes in the activity, conformation and microstructure of mushroom polyphenoloxidase (PPO) subjected to thermal treatment. The inactivation of PPO can be achieved by high temperature-short time or mild temperature-long time treatment. Circular dichroism and fluorescence spectra suggested that heating process induced the rearrangement of secondary structure and the disruption of tertiary structure. Red shifts of fluorescence spectra showed positive correlations with the inactivation rate of PPO. There were significant differences in the conformation and molecular microstructure among PPO samples with the same relative activity, which were obtained by treating PPO at 45, 55 and 65 °C for different times. In summary, PPO molecules were deformed at mild temperature, while higher temperature induced the formation of large aggregates. PPO with the same relative activity might exist in different forms.
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