Modification Of Surface Roughness Research Articles

Surface roughness model in experiment of grinding engineering glass-ceramics

The grinding experiment of mica glass-ceramics was conducted on the GM-D300-type surface grinder. The article investigated the influence of surface roughness on grinding wheel velocity, table feed speed, and grinding depth. The results indicated that surface roughness decreased with the increasing grinding wheel velocity and grinding depth in overall trend, and decreased with increasing table feed speed. Moreover, a modified surface roughness model, which introduced the maximum undeformed chip thickness, was developed based on Snoeys’ empirical formula. The modified model was in good agreement with the experimental data in most cases. The disparity between experimental data and predicted results of surface roughness was attributed to the organization of pores randomly distributed within the mica glass-ceramics.

Superamphiphobic surfaces

Superamphiphobicity is an effect where surface roughness and surface chemistry combine to generate surfaces which are both superhydrophobic and superoleophobic, i.e., contact angles (θCA) greater than 150° along with low contact angle hysteresis (CAH) not only towards probing water but also for low-surface-tension 'oils'. In this review, we summarize the research on superamphiphobic surfaces, including the characterization of superamphiphobicity, different techniques towards the fabrication of surface roughness and surface modification with low-surface-energy materials as well as their functional applications.

Surface finishing of cobalt chromium alloy femoral knee components

This paper describes the modification of surface roughness and lay of cobalt chromium alloy femoral knee components by magnetic abrasive finishing (MAF), including clarification of the MAF surface-processing mechanisms. The MAF process creates characteristic surfaces by micro-cutting of abrasive pressed by magnetic particles that nearly conform to the surface, removing large asperities and creating microasperities compared to hand-buffed surfaces. The process enables smoothing the surface on the nanometer scale with critical control of surface lay (e.g., crosshatch angle), altering the contact angle of water by a combination of kinematic behavior of magnetic particles over the freeform condyle surface.

Tribology, surface chemistry and morphology of WS2 tribofilms generated by the ANS triboconditioning process

ABSTRACTTriboconditioning is a mechanochemical surface finishing process developed for improving the tribological properties of mechanical components made of steel or cast iron. The process combines elements of extreme pressure mechanical burnishing of the component surface with a tribochemical deposition of a low‐friction anti‐wear film of tungsten disulphide (WS2). This allows one to produce, in a single finishing operation, a smoother surface with a significantly reduced coefficient of boundary friction and improved wear‐resistance and load‐carrying capacity.This study presents results of tribological rig tests carried out with valve train components and cylinder bores that underwent the triboconditioning treatment. The results show significant improvement in the tribological properties of triboconditioned components. The improvement is attributed to the formation of WS2 tribofilms at the component surface and a modified surface roughness profile with reduced core roughness (Rk) and peak height (Rpk). Elemental composition of the tribofilms generated by the triboconditioning process has been studied by X‐ray photoelectron spectroscopy and energy dispersive X‐ray spectroscopy the surface profile of the treated components has been studied using vertical scanning interferometry and the internal structure of the tribofilms has been studied with focused ion beam–transmission electron microscope technique. Copyright © 2013 John Wiley & Sons, Ltd.

Design of Biomimetic and Bioactive Cold Plasma-Modified Nanostructured Scaffolds for Enhanced Osteogenic Differentiation of Bone Marrow-Derived Mesenchymal Stem Cells

The objective of this study was to design a biomimetic and bioactive tissue-engineered bone construct via a cold atmospheric plasma (CAP) treatment for directed osteogenic differentiation of human bone morrow mesenchymal stem cells (MSCs). Porous nanocrystalline hydroxyapatite/chitosan scaffolds were fabricated via a lyophilization procedure. The nanostructured bone scaffolds were then treated with CAP to create a more favorable surface for cell attachment, proliferation, and differentiation. The CAP-modified scaffolds were characterized via scanning electron microscope, Raman spectrometer, contact angle analyzer, and white light interferometer. In addition, optimal CAP treatment conditions were determined. Our in vitro study shows that MSC adhesion and infiltration were significantly enhanced on CAP modified scaffolds. More importantly, it was demonstrated that CAP-modified nanostructured bone constructs can greatly promote total protein, collagen synthesis, and calcium deposition after 3 weeks of culture, thus making them a promising implantable scaffold for bone regeneration. Moreover, the fibronectin and vitronection adsorption experiments by enzyme-linked immunosorbent assay demonstrated that more adhesion-mediated protein adsorption on the CAP-treated scaffolds. Since the initial specific protein absorption on scaffold surfaces can lead to further recruitment as well as activation of favorable cell functions, it is suggested that our enhanced stem cell growth and osteogenic function may be related to more protein adsorption resulting from surface roughness and wettability modification. The CAP modification method used in this study provides a quick one-step process for cell-favorable tissue-engineered scaffold architecture remodeling and surface property alteration.

Synthesis and characterization of nanostructured poly(methyl methacrylate) for antireflection coating

Single layer coatings were prepared with poly(methyl methacrylate)/polystyrene nanoparticles blend by spin-coating, demonstrating excellent antireflection performance after selective removal of polystyrene particles. The thickness, refractive indices and surface roughness of the coatings, which significantly affect their optical performance, can be modulated by the coating conditions. The particle size can be well controlled by the operational conditions for the particle synthesis. The surface microscopic roughness of the coating strongly affects its light transmittance and the dimensionless parameter, roughness/wavelength ratio, dominates the deviation of the real transmittance from the theoretically predicted transmittance. By optimizing the reaction and the film preparation conditions, the transmittance of antireflection coatings can be up to 99.17% in the visible light range. Compared with work previously reported in the literature, the transmittance in the visible light range can be significantly improved via surface roughness modification, which was generally a problem, especially at the short wavelength region.

Characteristics of Ga-Al Doped ZnO Thin Films with Plasma Treatment Prepared by Using Facing Target Sputtering Method

Ga-Al-doped ZnO (GAZO) thin films were prepared on glass substrates using facing targets sputtering at room temperature. GAZO thin films have been treated in O2 plasma to modify surface roughness in order to enhance the efficiency of OLED anodes made from the films. After deposition of the thin films, the substrate was subjected to plasma surface treatment. The electrical, optical, and surface properties of the deposited thin films were investigated by hall-effect measurement, UV/Vis spectrometry, and atomic force microscopy (AFM), respectively. As a result of increasing the plasma treatment time from 0 to 45 sec, the surface roughness of films after plasma treatment was improved, but their electrical, optical, and structural properties were slightly changed. The lowest values of the surface roughness were 1.409 nm for the as-deposited GAZO thin films for an O2 plasma treatment time of 40 sec. All GAZO thin films have an average transmittance of 90% in the visible range (400-800 nm).

Evolution of damage fraction due to dense ionizing irradiation on TiO2 film

The evolution of damage fraction during dense ionizing irradiation at various fluences using 100MeV Ag ion is studied. Irradiation induced modification of surface roughness and surface potential of titanium dioxide nanocrystalline thin films are estimated. TiO2 thin films deposited on Si (100) substrate were irradiated by 100MeV Ag ion beam with varying fluences. Ion bombardment generates point and extended defects in TiO2 thin films due to dense electronic excitation. The surface morphology and surface roughness of irradiated and pristine thin films were measured using atomic force microscopy. The changes in surface potential of pristine as well as Ag ion beam irradiated thin films were measured from contact potential difference between TiO2 thin film (one electrode) of unknown work function and Au (reference electrode) of known work function using scanning Kelvin probe microscopy. The defect size and damage fraction are calculated from exponential fitting of variation of both contact surface potential difference and roughness exponent with fluence.

Effect of bleaching agents and soft drink on titanium surface topography

The effects of carbamide peroxide, hydrogen peroxide and cola soft drink on the topographic modifications of commercially-pure titanium (CP-Ti) and Ti-6Al-4V were investigated. Ti discs were divided into 18 groups (n = 4) based on the solution treatment and Ti type. Specimens were immersed in 3 mL of each solution for 4 h per day (for the remaining 20 h, discs were left dry or immersed in artificial saliva) for 15 days. For control, specimens were immersed in only artificial saliva. Ti surfaces were examined using scanning electron (SEM) and atomic force (AFM) microscopes and their surface roughness (in µm) and surface chemical modifications were investigated. Data were analyzed by ANOVA and Tukey's test (α = 0.05). Groups immersed in 35% hydrogen peroxide showed the highest roughness (Ra) (171.65 ± 4.04 for CP-Ti and 145.91 ± 14.71 for Ti-6Al-4V) (p < 0.05), followed by groups treated with carbamide peroxide 16% (110.91 ± 0.8 for CP-Ti and 49.28 ± 0.36 for Ti-6Al-4V) and 35% (65.67 ± 1.6 for CP-Ti and 53.87 ± 1.98 for Ti-6Al-4V); treatment with artificial saliva did not affect the results. These values were statistically superior to those observed prior to the treatment and to those of the control group (31.0 ± 0.99 for CP-Ti and 29.95 ± 0.58 for Ti-6Al-4V). Cola soft drink did not alter the surface roughness of either Ti type (p > 0.05). SEM and AFM revealed dramatic changes in the specimens surfaces immersed in the 35% hydrogen peroxide, mainly for CP-Ti. No detectable chemical modifications on the Ti surface were observed. Bleaching agents promoted significant changes in Ti topography, which could affect the longevity of implants treatments.

A semi-empirical inversion model for assessing surface soil moisture using AMSR-E brightness temperatures

Summary In 2004–2005, 2007 and 2009, three major drought disasters occurred in Guangdong Province of southern China, which caused serious economic losses. Hence, it has recently become an important research subject in China to monitor surface soil moisture (SSM) and the drought disaster quickly and accurately. SSM is an effective indicator for characterizing the degree of drought. First, using the brightness temperatures (Tb) of the Advanced Microwave Scanning Radiometer on the EOS Aqua Satellite (AMSR-E), a modified surface roughness index was developed to map the land surface roughness. Then by combining microwave polarization difference indices (MPDI)-based vegetation cover classification and the modified surface roughness index, a simple semi-empirical model of SSM was derived from the passive microwave radiative transfer equation using AMSR-E C-band Tb and observed surface soil temperature (Ts). The model was inverted to calculate SSM. The results showed the ability to discriminate over a broad range of SSM (7–73%) with an accuracy of 2.11% in bare ground and flat areas (R2 = 0.87), 2.89% in sparse vegetation and flat surface areas (R2 = 0.85), about 6–9% in dense vegetation areas and rough surface areas (0.80 ⩽ R2 ⩽ 0.83). The simulation results were also validated using in situ SSM data (R2 = 0.87, RMSE = 6.36%). Time series mapping of SSM from AMSR-E imageries further demonstrated that the presented method was effective to detect the initiation, duration and recovery of the drought events.

Influence of burst pulses on the film topography in picosecond pulsed laser deposition of LaAlO3

Using a commercial picosecond laser in a pulsed laser deposition setup for the deposition of LaAlO3 thin films, we showed that it is possible to obtain a wide range of different surface topography just by altering the temporal output of the laser pulses. In single-pulse mode, a highly structured surface is obtained independent of the laser fluence. As the number of burst pulses is increased from 2 to 10, the surface roughness gradually decreases to almost atomically smooth as investigated with scanning electron and atomic force microscopy. Studies by X-ray photoelectron spectroscopy revealed no significant variation in the film composition indicating that the burst mode only tunes the topography without affecting other parameters. The surface roughness modification is independent of the background pressure in a wide range, which opens up the possibility of using different reactive atmospheres, which could be used to tune the properties of the material even further.

Modification of Surface Roughness and Area of FeCrAl Substrate for Catalytic Converter using Ultrasonic Treatment

Surface roughness and area play important role especially in deposition and reaction of the catalyst in the catalytic converter substrate. The aim of this paper is to show the modification of surface roughness and area of FeCrAl substrate for catalytic converter using ultrasonic method. The method was conducted by agitating the FeCrAl in 10 minutes 35 kHz ultrasonic cleaning bath. The surface roughness, morphology, and chemical components of FeCrAl catalytic converter substrate after ultrasonic treatment were analyzed using atomic force microscope (AFM) and examined with scanning electron microscope (SEM) in combination with energy dispersive X-ray spectroscopy (EDS). The ultrasonic treatment assisted with Al2O3 powders successfully increased the roughness and surface area of FeCrAl better than SiC powders.

Coating pretreatment for Mg alloy AZ91D

Coating defects and coating failure upon Mg alloy AZ91D are usually due to non-uniform coating growth, which is intrinsically caused by the microstructural heterogeneity of the Mg substrate. This is the case for both conversion coatings and electroplated (incl. electroless) coatings. In the present study, coating pretreatment for the purpose of tailoring surface chemistry on AZ91D was studied. Pretreatments to control β-phase morphology and surface homogeneity include alkaline conditioning and acid activation in four different non-toxic (F-free) acid solutions: H3PO4, HNO3, HCl and C6H8O7. The results show that careful pretreatment can do all of the following: modify surface roughness; remove β-phase; modify solid solution chemistry; and most importantly, tailor the anodic/cathodic character of the surface. This allows surface pretreatment to be customized to optimize the subsequent coating. The influence of different acids was shown to be marked.

A Study of the Effect of Nitrogen and Air Plasma Immersion Ion Implantation Treatments on the Properties of Carbon Fiber

In this paper, plasma immersion ion implantation (PIII) treatments of carbon fibers (CFs) are performed in order to induce modifications of chemical and physical properties of the CF surface aimed to improve the thermoplastic composite performance. The samples to be treated were immersed in nitrogen or air glow discharge plasma and pulsed at <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$-$</tex></formula> 3.0 kV for 2.0, 5.0, 10.0, and 15.0 min. After PIII processing, the specimens were characterized by atomic force microscopy (AFM), scanning electron microscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). Surface morphology of as-received CFs exhibited some scratches aligned along the fibers due to the fiber manufacturing process. After both treatments, these features became deeper, and also, a number of small particles nonuniformly distributed on the fiber surface can be observed. These particles are product of CF surface sputtering during the PIII treatment, which removes the epoxy layer that covers as-received samples. AFM analyses of CF samples treated with nitrogen depicted a large increase of the surface roughness ( <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$Rrms$</tex></formula> value approximately six times higher than that of the untreated sample). The increase of the roughness was also observed for samples treated by air PIII. Raman spectra of all samples presented the characteristic D- and G-bands at approximately 1355 and 1582 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\hbox{cm}^{-1}$</tex></formula> , respectively. Analysis of the surface chemical composition provided by the XPS showed that nitrogen and oxygen are incorporated onto the surface. The polar radicals formed on the surface lead to increasing of the CF surface energy. Both the modification of surface roughness and the surface oxidation are expected to contribute for the enhancement of CF adhesion to the polymeric matrix used for composite manufacturing.

Membrane surface roughness characterization and its influence on ultrafine particle adhesion

Knowledge of the surface properties of ceramic membranes is useful for understanding and improving their filtration performance. In this study surface roughness was determined using a surface roughness tester (SRT). Roughness values were found to increase with increasing scan-length up to a scan-length of 4mm after which it remained relatively constant. Scanning electron microscopy (SEM), vertical scanning interferometry (VSI) and atomic force microscopy (AFM) were used to characterize the membrane morphology. Compared to AFM, VSI and SEM allow for rapid and accurate characterization of membrane roughness at substantially larger scan-sizes. Static adhesion tests showed that rougher surfaces have more adhesion to nanosized particles than smooth ones. In crossflow filtration, adhesion of nanosized particles smaller than or similar in size to the asperities depended mainly on the membrane roughness. At a certain roughness, a highest flux was obtained. But for microsized particles larger than the asperities, roughness had no evident effect on the flux. According to experimental results and the estimation of hydrodynamic forces acting on particles, fouling could be controlled by modification of surface roughness of ceramic membranes.

Enhancement of electrical properties in pentacene-based thin-film transistors using a lithium fluoride modification layer

We investigated the electrical performances of pentacene-based thin-film transistors with a thin LiF film as a modification layer between the source/drain electrodes and the active layer. Au, Pt, and Pd were employed as the source/drain (S/D) electrodes of the organic thin-film transistors (OTFTs). The thickness of the LiF layer was varied to optimize the electrical performances of the OTFTs. We found that the electrical performances of the devices with LiF layer are better than those without inserting the LiF layer, regardless of which one metal used for the S/D electrodes. The electrical performances of the devices in terms of drain current, on resistance, threshold voltage, on/off current ratio and mobility have been optimized when the thickness of the LiF buffer layer was at 1.0 nm. These improvements are attributed to work function of S/D contact materials were modified by the dipole of the inserted LiF layer and an ultrathin LiF layer provides the tunneling condition to enhance the carrier injection efficiently. Additionally, LiF layer with optimal thickness (1.0 nm) can modify surface roughness of pentacene film and partly enhance the carrier injection.

Effect of surface roughness and surface modification of indium tin oxide electrode on its potential response to tryptophan

The effect of surface modification of indium tin oxide (ITO) electrode on its potential response to tryptophan was investigated for ITO substrates with different surface roughness. It was found that a small difference in surface roughness, between ∼1 and ∼2 nm of R a evaluated by atomic force microscopy, affects the rest potential of ITO electrode in the electrolyte. A slight difference in In:Sn ratio at the near surface of the ITO substrates, measured by angle-resolved X-ray photoelectron spectrometry and Auger electron spectroscopy is remarkable, and considered to relate with surface roughness. Interestingly, successive modification of the ITO surface with aminopropylsilane and disuccinimidyl suberate, of which essentiality to the potential response to indole compounds we previously reported, improved the stability of the rest potential and enabled the electrodes to respond to tryptophan in case of specimens with R a values ranging between ∼2 and ∼3 nm but not for those with R a of ∼1 nm. It was suggested that there are optimum values of effective work function of ITO for specific potential response to tryptophan, which can be obtained by the successive modification of ITO surface.

Effects of O 2 and N 2/H 2 plasma treatments on the neuronal cell growth on single-walled carbon nanotube paper scaffolds

The O 2 and N 2/H 2 plasma treatments of single-walled carbon nanotube (SWCNT) papers as scaffolds for enhanced neuronal cell growth were conducted to functionalize their surfaces with different functional groups and to roughen their surfaces. To evaluate the effects of the surface roughness and functionalization modifications of the SWCNT papers, we investigated the neuronal morphology, mitochondrial membrane potential, and acetylcholine/acetylcholinesterase levels of human neuroblastoma during SH-SY5Y cell growth on the treated SWCNT papers. Our results demonstrated that the plasma-chemical functionalization caused changes in the surface charge states with functional groups with negative and positive charges and then the increased surface roughness enhanced neuronal cell adhesion, mitochondrial membrane potential, and the level of neurotransmitter in vitro. The cell adhesion and mitochondrial membrane potential on the negatively charged SWCNT papers were improved more than on the positively charged SWCNT papers. Also, measurements of the neurotransmitter level showed an enhanced acetylcholine level on the negatively charged SWCNT papers compared to the positively charged SWCNT papers.

Enhancement of surface wettability via the modification of microtextured titanium implant surfaces with polyelectrolytes.

Micrometer- and submicrometer-scale surface roughness enhances osteoblast differentiation on titanium (Ti) substrates and increases bone-to-implant contact in vivo. However, the low surface wettability induced by surface roughness can retard initial interactions with the physiological environment. We examined chemical modifications of Ti surfaces [pretreated (PT), R(a) ≤ 0.3 μm; sand blasted/acid etched (SLA), R(a) ≥ 3.0 μm] in order to modify surface hydrophilicity. We designed coating layers of polyelectrolytes that did not alter the surface microstructure but increased surface ionic character, including chitosan (CHI), poly(L-glutamic acid) (PGA), and poly(L-lysine) (PLL). Ti disks were cleaned and sterilized. Surface chemical composition, roughness, wettability, and morphology of surfaces before and after polyelectrolyte coating were examined by X-ray photoelectron spectroscopy (XPS), contact mode profilometry, contact angle measurement, and scanning electron microscopy (SEM). High-resolution XPS spectra data validated the formation of polyelectrolyte layers on top of the Ti surface. The surface coverage of the polyelectrolyte adsorbed on Ti surfaces was evaluated with the pertinent SEM images and XPS peak intensity as a function of polyelectrolyte adsorption time on the Ti surface. PLL was coated in a uniform thin layer on the PT surface. CHI and PGA were coated evenly on PT, albeit in an incomplete monolayer. CHI, PGA, and PLL were coated on the SLA surface with complete coverage. The selected polyelectrolytes enhanced surface wettability without modifying surface roughness. These chemically modified surfaces on implant devices can contribute to the enhancement of osteoblast differentiation.

Early implant healing: promotion of platelet activation and cytokine release by topographical, chemical and biomimetical titanium surface modifications in vitro

Platelet releasate has been shown to promote osteogenetic cell proliferation and differentiation. Topography and chemistry of biomaterials have high impact on platelet activation. More specifically, the bioactive cell adhesive peptide sequence Arg-Gly-Asp (RGD) triggers platelet activation mediated by the α(IIb) β(3) integrin receptor. Accordingly, topographical, chemical and biomimetical (immobilized RGD peptide) modifications of titanium (Ti) surfaces may enhance early platelet activation and bony healing of implants. Therefore, the aim of the study was to evaluate platelet activation with subsequent platelet-derived cytokine release by accordingly modified Ti surfaces. Pre-treated (PT; mean roughness [R(a)]=0.04 μm, contact angle [CA]=91°), acid-etched (A, R(a) =0.83 μm, CA=106°), large grit-sandblasted, acid-etched (SLA, R(a) =3.2 μm, CA=109°) as well as hydrophilically modified acid-etched (modA, R(a) =0.83 μm, CA=0) and modified large grit-sandblasted, acid-etched (modSLA, R(a) =3.2 μm; CA=0°) titanium surfaces were investigated. Additionally, RGD peptides were chemically immobilized on PT, A and SLA surfaces (PT-RGD [CA=18°], A-RGD [CA=0°], SLA-RGD [CA=0°]). The different Ti surfaces were incubated with platelet concentrate of three healthy volunteers at room temperature for 15 min and for 30 min. High thrombogenous collagen served as the control group. Out of the supernatant, platelet consumption was assessed via platelet count (PC). Cytokine release was quantified via the level of platelet-derived growth factor (PDGF) and vascular endothelial growth factor (VEGF). After 15 min, especially the rough SLA surface showed a strong decrease in PC and a strong increase in VEGF and PDGF levels. After 30 min, high platelet consumption as well as high levels of VEGF and PDGF were measured for unspecifically modified (modA) and especially for biomimetic, specifically modified (PT-RGD, A-RGD) surfaces, indicating a delayed effect of the surface modifications on platelet activation. Modifications of surface roughness modifications appear to influence early platelet activation and cytokine release after 15 min whereas surface chemistry modifications with increased hydrophilic properties and surface modifications via RGD peptide on plainer surfaces lead to a further, more specific promotion of platelet activation and degranulation after 30 min. The observed effect could be valuable for critical clinical situations like compromised bone sites.