Surface treatment Research Papers - Academia.edu (original) (raw)

The formation of a salivary pellicle is a prerequisite of bacterial colonization on the tooth, and the aim of this study has been to further the understanding of the role of surface properties in the formation of the salivary pellicle and subsequent adhesion of oral bacteria. Surface modification as a means of interfering with pellicle and plaque formation has been investigated. Five different silicone-containing compounds were used for the surface treatments: polydimethylsiloxane containing aminoalkyl groups {I), polydimethylsiloxane containing partially neutralized aminoalkyl groups (Ill, ethyl silicate (llt), potassium methyl siliconate (IV) and sodium silicate (V). Studies of water wetting, surface charge, oral bacterial adherence and pellicle formation were performed on glass slides and hydroxyapatite beads coated by the test compounds. No correlation was found between contact angle and surface charge, and evidently hydrophobicity, as expressed by water wetting, is not necessarily an indication of a low surface concentration of polar groups. All compounds reduced bacterial adherence after saliva contact, compound IV by around 90%. Different pauerns were seen in the adsorption of pellicle proteins on the different polysiloxanes.

- by Anette Carlén
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- Chemical Engineering, Biomedical Engineering, Hydroxyapatite, Surface modification
- by quirico semeraro
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- Engineering, Materials Science, Mathematical Sciences, Specification Tests

The bandgap of hydrogenated amorphous silicon (a-Si:H) is studied using a unique set of a-Si:H films deposited by means of three different processing techniques. Using this large collection of a-Si:H films with a wide variety of nanostructures, it is demonstrated that the bandgap has a clear scaling with the density of both hydrogenated divacancies (DVs) and nanosized voids (NVs). The presence of DVs in a dense a-Si:H network results in an anisotropy in the silicon bond-length distribution of the disordered silicon matrix. This anisotropy induces zones of volumetric compressed disordered silicon (larger fraction of shorter than longer bonds in reference to the crystalline lattice) with typical sizes of ∼0.8 up to ∼2 nm. The extent of the volumetric compression in these anisotropic disordered silicon zones determines the bandgap of the a-Si:H network. As a consequence, the bandgap is determined by the density of DVs and NVs in the a-Si:H network.

The aim of the study was to assess, compare and evaluate the adhesive strength and compressive strength of different brands of glass ionomer cements to a ceramometal alloy. (A) Glass ionomer cements: GC Fuji II (GC Corporation, Tokyo), Chem Flex (Dentsply DeTrey, Germany), Glass ionomer FX (Shofu-11, Japan), MR dental (MR dental suppliers Pvt Ltd, England). (B) Ceramometal alloy (Ni–Cr: Wiron 99; Bego, Bremen, Germany). (C) Cold cure acrylic resin. (E) Temperature cum humidity control chamber. (F) Instron Universal Testing Machine. Four different types of Glass ionomer cements were used in the study. From each type of the Glass ionomer cements, 15 specimens for each were made to evaluate the compressive strength and adhesive strength, respectively. The 15 specimens were further divided into three subgroups of five specimens. For compressive strength, specimens were tested at 2, 4 and 12 h by using Instron Universal Testing Machine. To evaluate the adhesive strength, specimens were surface treated with diamond bur, silicone carbide bur and sandblasting and tested under Instron Universal Testing Machine. It was concluded from the study that the compressive strength as well as the adhesive bond strength of MR dental glass ionomer cement with a ceramometal alloy was found to be maximum compare to other glass ionomer cements. Sandblasting surface treatment of ceramometal alloy was found to be comparatively more effective for adhesive bond strength between alloy and glass ionomer cement.

- by sunit jurel
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- Silicon Carbide, Compressive Strength, Bond Strength, Surface treatment

Aim of the investigation was to assess the effect of different surface treatments on the bond strength of veneering ceramics to zirconia. In a shear test, the influences of polishing, sandblasting, and silica-coating of the zirconia surface on bonding were assessed with five different veneering ceramics. In addition the effect of liner application was examined. With one veneering ceramic, the impact of regeneration firing of zirconia was also evaluated. Statistical analysis was performed with one-way ANOVA and post hoc Scheffé's test. Failure in every case occurred in the veneering ceramic adjacent to the interface with a thin layer of ceramic remaining on the zirconia surface, indicating that bond strength was higher than the cohesive strength of the veneering ceramic. Shear strength ranged from 23.5±3.4MPa to 33.0±6.8MPa without explicit correlation to the respective surface treatment. Regeneration firing significantly decreased the shear strength of both polished and sandblasted surfaces. Findings of this study revealed that bonding between veneering ceramics and zirconia might be based on chemical bonds. On this note, sandblasting was not a necessary surface pretreatment to enhance bond strength and that regeneration firing was not recommended.

- by Bogna Stawarczyk
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- Dentistry, Biomedical Engineering, Dental Materials, Prosthetic Dentistry

We describe a new surface treatment to obtain optical films for liquid crystal display (LCD) applications. The films consist of a phaseseparated layer including a fluorine-containing (FC) compound and a widely used polymer resin for providing a hard coating after surface treatment of the optical film. The major features of the resulting configuration are high durability with a good hardness of above 4H and a surface that allows oily contaminants such as ink and fingerprints to be easily removed by gentle dry wiping, owing to the antismudge function of the FC compound with a low surface energy. #

- by Il Jeon
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- Mathematical Sciences, Physical sciences, Surface treatment, Phase Separation

It has been shown that the surface properties of titanium and its alloys, in particular the resistance to 'galling' and wear, can be enhanced by surface treatmentycoating based on chemicalyphysical vapour deposition or ion implantation processes. Surface alteration of Ti arising from two processing routes, IonSlip and diamond-like carbon deposition, have been characterized by Raman and surface-specific electron spectroscopies, and then correlated with surface-mechanical properties. ᮊ

- by Alison Crossley
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- Engineering, Technology, Raman Spectroscopy, Titanium

"A target of Fe-40 at.-%Al intermetallic alloy with ordered B2 structure was subjected to laser melting processing by a high energy XeCI excimer pulse (wavelength 308 nm, pulse length 120 ns) in low pressure air. The total thickness of the laser affected zone (LAZ) was ∼ 150 nm. The modified surface showed an increased roughness and the presence of cracking. The X-ray photoelectron spectroscopy (XPS) measurements revealed a strong enrichment in the aluminium concentration within the LAZ, as well as relatively high contents of oxygen and nitrogen incorporated in the near surface region. Both angle resolved and depth profile XPS analyses suggested that oxides, nitrides, and oxynitrides were mainly present within the LAZ as discrete particles in the metallic matrix rather than as surface layers. Significant surface hardness reduction was observed after laser treatment, which has been interpreted to be due to partial suppression of B2 lattice ordering. Electrochemical measurements in borate buffer solution showed a reduced anodic activity of the laser processed aluminide in the potential range between the open circuit potential and 0.1 V saturated calomel electrode, whereas at higher anodic overpotentials no substantial differences in behaviour were observed with respect to the untreated Fe–40Al surfaces. Such consequences of the excimer laser treatment may be explained by mechanisms involving aluminium enrichment and nitride formation processes inside the LAZ."

- by Paolo Di Lazzaro
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- Surface Science, Laser-Matter interactions, Surface Texturing, Aluminium Alloys

This paper studies the eciency of high-power laser methods for modifying the AISI 304 steel surface in order to increase its corrosion resistance. The surface of SS 304 was melted in argon and nitrogen atmospheres using dierent laser beam scan rates and gas¯ows. The results obtained show that in both cases the laser surface melting (LSM) induced improvements in pitting resistance with respect to the base steel. Electrochemical studies showed that the improvements are greater when the LSM is carried out in a nitrogen environment because of the incorporation of nitrogen into solid solution. As a result, the corrosion and pitting potential shift to more noble values while the passive current density decreases by nearly two orders of magnitude. The presence of chromium oxides and nitrogen compounds on the surface of the specimens seem to indicate that nitrogen may help the reconstruction of the passive layer as well as act as a barrier for the electrolyte. Ó

- by Angel Conde
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- Materials Engineering, Mechanical Engineering, Civil Engineering, Corrosion Science

The relationship between the rate of polymer delamination and the intensity of either anodic or cathodic current under the paint has been investigated for the zinc/surface treatment/ polymer system by using a special electrochemical cell. Three types of surface treatment were investigated: simple alkaline degreasing, trication phosphating, and a chromate free conversion coating. Significant differences were observed for the three substrates. The alkaline resistance of the conversion coatings was determined using an ICP atomic emission spectroelectrochemical method. The results are interpreted in terms of the differing chemical stability of the conversion layers towards hydroxide generated by oxygen reduction.

- by Kevin Ogle
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- Materials Engineering, Mechanical Engineering, Civil Engineering, Corrosion Science

The effectiveness of concrete surface treatment materials such as silanes, siloxanes, etc., in preventing concrete deterioration due to sulfate attack, carbonation, and chloride-induced reinforcement corrosion was investigated. The... more

- by Mohammed ibrahim
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- Materials Engineering, Civil Engineering, Materials Science, Materials

The effect of surface treatment on silica agglomerate dispersibility was investigated. Precipitated silica powders were treated with a commercially available coupling agent Bis-(triethoxysilylpropyl)-tetrasulphane (TESPT) in a blender. Spherical agglomerates of known density were prepared and dispersed in styrene butadiene rubber (SBR) under controlled flow conditions. The erosion kinetics was monitored by measuring the reduction in size of parent agglomerate with time. Silica dispersibility was greatly enhanced upon surface treatment. The coupling agent used in surface treatment is known to reduce filler—filler interactions and therefore affects the intrinsic cohesivity of the powder. However powder surface treatment can also induce changes in agglomerate morphology and filler-liquid interactions. The work presented in this paper evidences such changes.

- by Donald L Feke
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- Kinetics, Morphology, Silica, SBR

The effect of different mechanical and chemical pre-treatments on the adhesion strength of hydroxyapatite (HAp) coating on a commercially pure titanium (CP-Ti) substrate was studied by means of a standard tensile test followed by microscopic and chemical analysis to determine the locus of fracture. In addition, the effects of either these pre-treatments or post-treatment by low-energy electron irradiation, which allowed tuning the wettability of the surface, on both osteoblast progenitor attachment and S. aureus bacteria attachment were investigated. A dedicated program was developed for unambiguous identification and count of stained cells. A single-phase HAp coating was formed by electrodeposition. A series of surface pre-treatments consisted of grinding down to P1000, etching in HNO 3 /HF solution, grit blast, soaking in NaOH and subsequent heat treatment provided the highest adhesion strength to the HAp coating. Osteoblast progenitors derived from rats may be attached preferentially to a hydrophilic surface (post-treatment to h = 30°), while the bacteria seemed to be less attached to hydrophobic surfaces (post-treatment to h = 105°). However, the results were not statistically different. The bacteria seemed to be less attached to the smoother, uncoated surfaces.

- by Daniel Aronov
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- Materials Engineering, Biomedical Engineering, Hydroxyapatite, Cell Adhesion

Rainwater harvesting is being promoted to solve water problems for agricultural and domestic uses in the semiarid loess regions of China. In recent years, however, the current rainwater harvesting practices are still confined to rural family units to supply household water needs and for very limited supplemental irrigation purposes due to low runoff efficiencies of the limited catchment types and consequently low amount of collected water. The current runoff catchments mainly include rooftops, courtyards, earth and asphalt-paved roads. It is necessary to test artificial catchment treatments to select optimum treatments for large-scale use in the region. This study evaluated runoff characteristics of six surface treatments relative to rainfall amount and intensity and antecedent rainfall during naturally occurring rainfall events in the semi-arid loess regions of northwest China. The surface treatments included two basic types, i.e., earthen (natural loess slope and cleared loess slope) and barrier-type surface treatments (concrete, asphalt--fiberglass, plastic film, and gravel covered plastic film).The results of the study indicated that runoff and runoff efficiency of the earthen surface treatments were closely related to the rain intensity, while runoff from the asphalt fiberglass, plastic film, gravel-covered plastic film, and concrete surface treatments was more governed by the amount of the rainfall. Asphalt fiberglass had the highest average annual runoff efficiency of 74–81%, followed in decreasing order by the plastic film (57–76%), gravel-covered plastic film (56–77%), concrete (46–69%), cleared loess slope (12–13%), and natural loess slope (9–11%). Antecedent rainfall had an obvious effect on the runoff yield for the cleared loess slope, natural loess slope, and concrete. The threshold rainfall was 8.5, 8.0, and 1.5 mm for the natural loess slope, cleared loess slope, and concrete treatments, respectively, without antecedent rainfall effects and 6.0, 5.0, and 1.2 mm, respectively, with antecedent rainfall effects. Due to the impermeable surface, antecedent rainfall had little effect on the runoff yield for the asphalt fiberglass, plastic film, and gravel-covered plastic film treatments, which had a threshold rainfall of 0.1, 0.2, and 0.9 mm respectively.

- by Klementina Zupan
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- Engineering, Carbon, Atomic Force Microscopy, Physical sciences

Any heat treatment induce residual stresses and residual deformations which can play a major role on the mechanical strength and the quality of a mechanical component. Moreover, in the highly competitive industry, heat treatment processes become more and more sophisticated and require to be accurately defined. The increase of computer capabilities combined with the development of modelling technologies enable today to achieve numerical simulations of manufacturing processes involving complex interactions between several physical phenomena. For the simulation of bulk and surface heat treatments, one key point for the prediction of residual stresses and distortions is the modelling of material modifications and their consequences on the thermal and mechanical behaviour. The aim of this paper is to discuss the contribution of numerical techniques to the analysis of bulk and surface heat treatments and the way the different physical phenomena involved have to be taken into account. The finite element implementation of coupled heat transfer, metallurgy and mechanical analysis in SYSWELD® will be detailed. At last, industrial applications will be discussed. Our experience mainly concerns steel components and so this paper will focus on steel. Nevertheless, aluminium alloys models have been recently implemented in the software for welding applications. These models will be briefly presented.

- by F. Boitout and +1
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- Heat Transfer, Heat Treatment, Finite Element, Numerical Simulation

This work is focused on the development of plasma diffusion treatments for stainless steels to obtain a higher conductivity of bipolar plates in fuel cells and secondly, to avoid hydrogen embrittlement of stainless steels in case of high pressure hydrogen storage systems by the formation of a single γ C layer. Electrical conductivity and corrosion resistance were enhanced by plasma nitriding. Tests with single cells have shown a 15% higher voltage compared to graphite plates at low temperatures and reduced treatment durations. The substitution of high alloyed stable stainless steel grades by cheaper metastable stainless grades depends on a successful suppression of hydrogen environmental embrittlement. A promising way could be a surface treatment resulting in the formation of a γ C layer on top of the surface. Plasma nitrocarburizing can form such γ C layer, but a variation of treatment temperature and CH 4 content was not successful in suppressing the undesired S-phase as a top layer.

- by Peter Kaestner and +1
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- Materials Engineering, Condensed Matter Physics, High Pressure, Hydrogen Storage

In this study, the effects of various surface treatments on the friction and wear behavior of AISI 4140 steel have been evaluated. Sample surfaces of AISI 4140 steel were treated by quenching, carburizing, boronizing and plasma transferred arc (PTA) modification. The microstructural characteristics of surface treated steel samples were examined by optical microscopy and scanning electron microscopy (SEM). The mechanical properties of the samples including the surface roughness, microhardness, and abrasive and adhesive wear characteristics were also evaluated. Wear tests were applied by using a block-on-disc configuration under dry sliding conditions. The wear behavior and friction characteristics of the samples were determined as a function of sliding distance. Each sample group was compared with the other sample groups, and it was observed that the carburized samples demonstrated the lowest weight losses; however, PTA-treated samples demonstrated the lowest coefficient of friction in comparison to the other sample groups at the same sliding distance.

- by Osman Çelik
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- Materials Engineering, Mechanical Engineering, Materials Science, Sliding wear

Bulk characteristics and deposition of gold nanoparticles on mica modified by (PAH) was studied byUV–visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM),dynamic light scattering (DLS) and atomic force microscopy (AFM). The size of gold nanoparticles (AuNPs)was 15 nm as determined by TEM and AFM. The electrophoretic mobilities and electrokinetic chargeof particles were quantitatively evaluated for a broad range of pH and ionic strength. Using Henry’smodel, it was calculated that the zeta potential of particles varied between − 50 mV and − 80 mV forpH 2 and pH 11, respectively (at 10−2M of NaCl). Measurements of nanoparticle deposition kineticswere performed under diffusion-controlled transport conditions using AFM and SEM imaging of particlemonolayers. The influence of the bulk suspension concentration was systematically studied. Additionally,the maximum coverage of particle monolayers, which monotonically increased with ionic strength, wasdetermined by SEM. The obtained data were in agreement with theoretical predictions derived from therandom sequential adsorption (RSA) model. It was also confirmed that by varying the bulk suspensionconcentration and ionic strength one can prepare homogeneous gold particle monolayers of controlledcoverage.

Objectives. The purpose of this study was to investigate the effect of different surface treatments on the bond strength () of repaired, aged resin composites (ARC). Methods. Forty blocks of Filtek Z250 TM (Z2) and Filtek Supreme TM (SU) were made, stored in deionized water for 9 days, and randomly assigned to different surface treatment groups: hydrofluoric acid etching (HA), abrasion using a coarse diamond bur (AB), sandblasting with alumina particles (AO), and silica coating (SC). The average roughness (Ra) of the treated surfaces was measured with a profilometer. An adhesive system (SB-Adper Single Bond Plus TM), a silane (SI) or a combination of both (SI + SB) were applied after each surface treatment. The blocks were restored with the same composite (RC) and cut to produce bars that were turned into dumbbell-shaped specimens (0.5 mm 2) using a precision grinding machine. The specimens (n = 30) were tested in tension to fracture and the microtensile bond strength () values were calculated (MPa). Data were analyzed using three-way ANOVA/Tukey test (˛= 0.05) and Weibull statistics. Results. AO and SC produced similar Ra values, which were greater than the value produced by HA. The values were statistically influenced by the type of RC (p < 0.0001), by the surface treatment (p < 0.0001) and by the surface coating (p < 0.0001). Treating the surface of Z2 with SC + SB produced the greatest m value. Significance. AO and SC produced the greatest values, irrespective of the primer (SI, SB or SI + SB) used. Yet, the RC microstructure influenced the mean values, which were greater for Z2 than for SU. The HA should not be used for repairing ARC.

- by Shaymaa Elsaka
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- Engineering, Survival Analysis, Nanocomposites, Dental Materials

The chemical surface modifications of jute fabrics involving bleaching, dewaxing, alkali treatment, cyanoethylation and vinyl grafting are made in view of their use as reinforcing agents in composites based on a biodegradable polyester amide matrix, BAK 1095. The effect of different fibre surface treatments and fabric amounts on the performance of resulting composites are investigated. The mechanical properties of composites like tensile and bending strengths increase as a result of surface modification. Among all modifications, alkali treatment and cyanoethylation result in improved properties of the composites. The tensile strength of BAK is increased by more than 40% as a result of reinforcement with alkali treated jute fabrics. SEM investigations show that the surface modifications improve the fibre-matrix interaction. From degradation studies we find that after 15 days of compost burial about 6% weight loss is observed for BAK whereas cyanoethylated and alkali treated jute-BAK composites show about 10% weight loss. The loss of weight as well as the decrease of bending strength of degraded composites is more or less directly related. ᭧

Bond failures at the acrylic teeth and denture base resin interface are still a common clinical problem in prosthodontics. The effect of methyl methacrylate (MMA) monomer on the bond strength of three types of denture base resins (Acron MC, Lucitone 550 and QC-20) to two types of acrylic teeth (Biotone and Trilux) was evaluated. Twenty specimens were produced for each denture base resin/acrylic tooth combination and were randomly divided into control (acrylic teeth received no surface treatment) and experimental groups (MMA was applied to the surface of the acrylic teeth for 180 s) and were submitted to shear tests (1 mm/min). Data (MPa) were analyzed using three-way ANOVA/Student's test (a ¼ 0.05). MMA increased the bond strength of Lucitone denture base resins and decreased the bond strength of QC-20. No difference was detected for the bond strength of Acron MC base resin after treatment with MMA.

- by Marco Compagnoni and +1
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- Materials Engineering, Mechanical Engineering, Chemical Engineering, Adhesion

In this work the effects of both the substrate surface condition and the adhesive properties on single-lap aluminium joint resistance were analysed. The aluminium sheets were mechanically treated with two abrasive surfaces evaluating the induced roughness; four different resins were used in adhesion tests. Moreover, wettability tests were performed in order to evaluate the effect of the abovementioned parameters on the substrate/adhesive interaction. A design of experiments was defined in order to quantify the effect of the considered factors and their correlation.

- by Chiara Borsellino
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- Materials Engineering, Mechanical Engineering, Chemical Engineering, Adhesion

Flame retardant challenges for textiles and fibres: new chemistry versus innovatory solutions.

Surface damage & morphology Surface treatments Yttria-stabilized tetragonal zirconia polycrystal a b s t r a c t This paper studied the surface quality (damage, morphology, and phase transformation) of yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) in CAD/CAM milling, and subsequent polishing, sintering and sandblasting processes applied in dental restorations. X-ray diffraction and scanning electron microscopy (SEM) were used to scan all processed surfaces to determine phase transformations and analyse surface damage morphology, respectively. The average surface roughness (R a) and maximum roughness (R z) for all processed surfaces were measured using desk-top SEM-assisted morphology analytical software. X-ray diffraction patterns prove the sintering-induced monoclinic-tetragonal phase transformation while the sandblasting-induced phase transformation was not detected. The CAD/CAM milling of pre-sintered Y-TZP produced very rough surfaces with extensive fractures and cracks. Simply polishing or sintering of milled pre-sintered surfaces did not significantly improve their surface roughness (ANOVA, p40.05). Neither sintering-polishing of the milled surfaces could effectively improve the surface roughness (ANOVA, p40.05). The best surface morphology was produced in the milling-polishing-sintering process, achieving R a ¼0.2170.03 mm and R z ¼1.7370.04 mm, which meets the threshold for bacterial retention. Sandblasting of intaglios with smaller abrasives was recommended as larger abrasive produced visible surface defects. This study provides technical insights into process selection for Y-TZP to achieve the improved restorative quality. (L. Yin). j o u r n a l o f t h e m e c h a n i c a l b e h a v i o r o f b i o m e d i c a l m a t e r i a l s 6 5 (2 0 1 7) 1 0 2 – 1 1 6

The polymer materials are likely to suffer constrai nts leading to the formation of cracks and fissures , often in depth, where their detection remains difficult and their repair virtually impossible. These cracks are at the origin of adverse consequences as degradation or a dysfunction of the system. To remedy all these problems, the self ("S elf-Healing") appears as the

- by Cristina Nistor and +1
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- Scanning Electron Microscopy, Infrared spectroscopy, Surface treatment

- by Marco Compagnoni
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- Materials Engineering, Mechanical Engineering, Chemical Engineering, Adhesion

The effect of exposure to different ozone concentrations, in conjunction with UV radiation, on the surface modification and adhesion properties of a block synthetic styrene-butadiene-styrene (S6) rubber was studied. The treatment time varied between 10 s and 30 min. Three different surface treatments were investigated: ozone only (O 3 ), UV radiation in the presence of air, and UV radiation in the presence of externally generated, supplemental ozone (UV/O 3 ). The surface modified S6 rubber was characterized using contact angle measurements (ethylene glycol, 25 1C), Fourier transform infrared spectroscopy using an attenuated total reflection attachment (ATR-IR), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). T-peel tests of surface modified S6 rubber/polyurethane (PU) adhesive/leather joints were carried out to quantify the changes in the adhesion properties.

Post-consumer glass represents a major component of solid waste. On the other hand, more than 100 million tons of coal combustion ash are generated in the U.S. annually, of which 60 million tons are fly ash. To deal with these problems, two new materials were developed: "glascrete" and "ashcrete." They have the potential of being made almost entirely from recycled materials: crushed mix-color waste glass as aggregate and activated fly ash (or portland cement) as cementitious binder. The combination of waste glass with portland cement or with activated fly ash offers an economically viable technology for high-value utilization of the industrial wastes. Disposal of waste tires is another serious environmental problem in the U.S. Two innovative materials were developed for utilization of rubber particles in concrete: rubber modified concrete (RMC) and sulfur rubber concrete (SRC). In RMC, the strength loss of the concrete is minimized, and the toughness of the concrete is enhanced by surface treatment of the rubber particles using coupling agents. In SRC, waste rubber particles are mixed in sulfur concrete, and the partial vulcanization process between the rubber and hot sulfur improves the strength of SRC.

- by Alabi Stev
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- Solid waste, Fly Ash, Surface treatment, Industrial Waste

This experimental study was performed with intent to improve the surface properties of titanium and to minimize the friction on ceramic. Its main object was to strengthen the resistance against wear resulting from dry-sliding contact. Titanium-covered or not, graphite powder was irradiated and superficially melted by means of a pulsed Nd-YAG laser beam. Different irradiations were carried out, changing the distance between irradiated surface and laser beam focal plane. The variations in the dry-sliding friction coefficient were recorded using a pin-on-disc tribometer. An optimum irradiation of graphite-covered titanium generated hard granular titanium carbide and lubricating graphite inclusions which drastically reduced dry friction and wear of the Laser-Melted Zone. In this way, a self-lubricating composite coating has been successfully synthesized on titanium from the laser melting process. q 1999 Elsevier Science S.A. All rights reserved.

- by Stéphane Benayoun
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- Materials Engineering, Mechanical Engineering, Titanium, Wear

Generation and features of the radio frequency (rf) hollow cathode discharge (HCD) and its transition into the hollow cathode arc (HCA) are described. Rf linear hollow cathodes for generation of plasma over large areas and suitable for further scale-up are presented. Examples of surface processing and coating by PVD, both by HCD and HCA, are given. The hybrid reactor, combining hollow cathode and microwave plasmas, integrates features of both and provides more options to control plasma characteristics and consequently properties of deposited films. The rf hollow cathodes can be operated in both, PVD and PE CVD regimes, depending on process parameters. These regimes can even be combined within one process. New concepts of fused hollow cathode (FHC), microwave antenna (MWA) and Hybrid hollow electrode activated discharge (H-HEAD) cold atmospheric plasma sources are introduced. The FHC with its modular concept can be used for gas conversion, cleaning and for surface treatment of temperature-sensitive materials at ambient atmosphere. The H-HEAD cold atmospheric plasma source, capable of generating plasma plumes more than 15 cm long, enables treatment of 3-d and complex geometry objects even at low gas flows.

- by Ladislav Bardos
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- Materials Engineering, Pulsed Power, Plasma Processing, Radio Frequency

A sepiolite silicate was heat-treated at 550 and 1000°C to modify its structure, and was used as a filler in a solvent-based polyurethane (PU) adhesive. The treated sepiolites were characterized by X-ray diffraction and infra-red spectroscopy, and it was observed that the water was irreversibly removed from the structure and pores of the sepiolite, changing the structure. The increase of temperature produced a collapse of the sepiolite structure. The rheological, mechanical, thermal and adhesion properties of the filled PU adhesives were measured. In general, the addition of treated sepiolite to PU adhesives resulted in a loss of adhesive properties with respect to the blank (PU adhesive with untreated sepiolite). The loss in properties was more noticeable as the treatment temperature increased. Thus the PU adhesives containing treated sepiolite had reduced rheological properties (lower viscosity, lower storage and loss moduli, and they did not provide thixotropy and pseudoplasticity to the solutions) with respect to the PU adhesive filled with untreated sepiolite. On the other hand, the addition of treated sepiolite decreased the mechanical and thermal mechanical properties of PU films. The T-peel strength of roughened and roughened+chlorinated (with l wt% trichloroisocyanuric acid in 2-butanone) styrene-butadiene rubber/PU adhesive joints was improved if the PU adhesive contained untreated sepiolite, but it decreased if the sepiolite was heat-treated. Interactions between the untreated sepiolite, the solvent and the polyurethane were responsible for the improved properties of PU adhesives. These interactions disappeared when the sepiolite was heattreated, because of the destruction of the structure of the sepiolite and the removal of surface silanol groups. © 1997 Elsevier Science Ltd (Keywords: A. polyurethane; A. solvent based; B. rubber; B. surface treatment; C. infrared spectra; C. dynamic mechanical analysis; C. rheology; D. viscoelasticity)

This study evaluated the effect of three post surface treatments on quartz-fiber post (a) retention and (b) morphology. A control group was not treated. Different treatments were performed for the other posts: silanization; etching by hydrofluoric acid 9.5%; sandblasting with 50 m Al 2 O 3 . Two specimens of each group were submitted to a qualitative scanning electron microscopy (SEM) analysis. Remaining specimens were luted in prepared root canals (n ϭ 10) and retentions were determined using a universal testing machine. Retentive post bond strengths were significantly enhanced with any tested post surface pretreatment. The increase in retentive strength was more remarkable in sandblasted and etched posts. Significant changes of post surfaces were SEM observed after different conditioning treatments. (J Endod 2007;33: 264 -267)

- by Sergio Caputi
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- Dentistry, Water, Nonparametric Statistics, Scanning Electron Microscopy

Galvanized steel structures are used in a large variety of external constructions in the modern urban society, and their beneficial properties from a corrosion and oxidation perspective are well known. Less investigated is the extent of their contribution to the diffuse dispersion of zinc in the society and also to the environmental fate of corrosion-induced released zinc. This paper presents long-term runoff rates of zinc from galvanized steel surfaces with main focus on hotdipped galvanized steel exposed for up to 10 years at nonsheltered urban atmospheric conditions. The long-term capacities of a naturally formed patina and the presence of surface treatments and coatings to hinder and reduce corrosion-induced zinc runoff from galvanized steel are elucidated. The environmental interaction of zinc runoff and concrete surfaces in pavement and urban storm drain systems is highlighted and the high capacity of concrete to retain released zinc presented.

- by Inger Odnevall
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- Environmental Monitoring, Steel Structure, Corrosion, Multidisciplinary

The importance of biomaterials has been recognized in biomedical research for over three decades. Their practical utilization in biomedical applications depends on the appropriate physical and biological responses collectively referred to as biocompatibility. The response of biomaterials in a biological environment is characteristically associated with their surface properties. The modification of biomaterials by various surface treatments has recently become an active topic in surface engineering. A number of research groups have focused on the preparation of surfaces with a gradually varying chemical composition along one dimension. Such a ''gradient surface'' is of particular interest for basic and applied studies of the interactions between biological species and surfaces as the dependence of a selected property, such as wettability, on composition, can be examined in a single experiment on one surface.

- by Gilson Khang
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- Engineering, CHEMICAL SCIENCES, Surface treatment, Surface Properties

In this paper the usability of two casting methods, of sand and high pressure cast for the anodization of AlSi12 and AlSi9Cu3
aluminium cast alloys was investigated. With defined anodization parameters like electrolyte composition and temperature, current type and value a anodic alumina surface layer was produced. The quality, size and properties of the anodic layer was investigated after the anodization of the chosen aluminium cast alloys. The Alumina layer was observed used light microscope, also the mechanical properties were measured as well the abrasive wear test was made with using ABR-8251 equipment. The researches included analyze of the influence of chemical composition, geometry and roughness of anodic layer obtained on aluminum casts. Conducted investigations shows the areas of later researches, especially in the direction of the possible, next optimization anodization process of aluminum casting alloys, for
example in the range of raising resistance on corrosion to achieve a suitable anodic surface layer on elements for increasing applications in the aggressive environment for example as materials on working building constructions, elements in electronics and construction parts in air and automotive industry.

- by Krzysztof Labisz and +1
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- Anodization, Mechanical Properties of Materials, Surface treatment, Aluminium Cast Alloys

Back tempering, a well known problem in laser hardening of steels, occurs when a large area is hardened by multiple overlapping passes. The overlapping passes partially temper the previous hardened material in the overlapped zone. Back tempering also occurs in circular laser hardening, a typical laser surface treatment used in case of cylindrical workpieces, since the treated starting/ending surfaces are slightly overlapped. In order to avoid the back tempering phenomenon the apparent spot (AS) technique is addressed and investigated. In case of circular laser hardening the AS technique is based on imposing a high rotational speed to the workpiece, since an apparent circular spot is generated, which contemporaneously heats all the annular surface of the workpiece. As a consequence, backtempering is avoided. In this paper an experimental campaign is deigned to analyze the effects of the process parameters (laser power, workpiece rotational speed and workpiece diameter) on the hardened tracks in terms of width, thickness and hardness values, when the AS is applied to the circular laser hardening.

- by Luca Giorleo and +1
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- Surface treatment, Process Parameters

Adsorption behavior of molybdate and tungstate from water by acid-treated carbon cloth was investigated. The carbon cloth was treated with sulfuric acid and used for the adsorption of molybdate and tungstate from water samples at nearly neutral solutions. The concentration of ions in the solution was monitored using in situ UV spectroscopy. Acid treatment caused a significant increase in the adsorption rate of ions and the adsorption capacity of the adsorbents. The adsorption isotherm data for the anions were derived at 25EC and treated according to Langmuir and Freundlich models and was found that both models were almost equally successful. Adsorption capacities determined from Langmuir isotherms of anions showed that molybdate has greater adsorption capacity than tungstate.

- by Abbas Afkhami and +1
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- Engineering, Activated Carbon, Desalination, CHEMICAL SCIENCES

Hot rolled steel (HRS) is used extensively in the automotive, agricultural and appliance industries. The corrosive response of HRS was investigated after it had been exposed to various surface treatments, prior to powder coating. The behaviour of three conversion coatings: zinc phosphate (ZnP), iron phosphate (FeP) and zirconium (Zr)-based nano-scaled, on HRS was studied. HRS is naturally covered with iron oxide scale and this was removed from the surface by mechanical and chemical processes, prior to the application of surface treatment and organic coatings. The following tests on differently treated panels were conducted to evaluate corrosion performance: adhesion tests such as, crosshatch, pull-off, and conical bending, SEM, XPS, salt spray and electro-chemical impedance studies were also performed. Good correlations were recorded showing that zinc phosphate conversion coating gave the best performance, and zirconium-based nano-structured conversion coating, was superior to that of iron phosphate conversion coatings on HRS.

- by Banihan Gunay
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- Materials Engineering, Mechanical Engineering, Iron Oxide, Zinc

This paper, based on an orthogonal experimental design and analysis method, reports the effects of a dielectric barrier discharge (DBD) plasma surface treatment on polytetrafluoroethylene (PTFE), polyimide (PI) and poly (lactic acid) (PLA) films in terms of changes in surface wettability and surface chemistry. The purpose was to study the influence of the main operating parameters, i.e. plasma power, treatment period duration (treatment cycles) and electrode gap on the resultant surface properties. Statistical analysis was carried out to develop an equation which expresses surface properties (water contact angle and oxygen enrichment, as observed by XPS analysis) in terms of these operational parameters. It was observed that the plasma parameters have a selective effect on the changes observed for the polymers processed. In particular, plasma processing time (treatment cycles), plays an important role in the treatment of PTFE and PI in this study, whereas the size of the electrode gap plays the dominant role in the treatment of PLA. Fast surface activation can be achieved in all cases after only a few seconds of treatment duration. The wettability improvement observed in all cases was attributed to changes in both surface chemistry and surface micro-structure. D

Thermoplastics are highly attractive substrate materials for microfluidic systems, with important benefits in the development of low cost disposable devices for a host of bioanalytical applications. While significant research activity has been directed towards the formation of microfluidic components in a wide range of thermoplastics, sealing of these components is required for the formation of enclosed microchannels and other microfluidic

- by Leo Devoe
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- Materials Science, Microstructure, Microfluidics, Nanotechnology

An overview is represented of the cryogenic technologies implementation in the heat treatment and deformation of metals. The areas are determined of most effective application of the cryogenic liquids and gases in the steel rolling production and heavy machines building with the aim of product quality improving, equipment and tools durability and reducing ecology impact on environment and working personnel.

- by Pavlo Krot
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- Cold Rolling and Galvanising of Steel, Cooling, Surface treatment, Cryogenic Machining

Materials used in medicine should fulfill several strict conditions primarily imposed by biological restrictions: absence of harmful interactions with body cells, good compatibility with organs and, finally, suitable mechanical properties. These conditions are often contradictory; hence, only exceptionally single-phased materials can provide the best choice and the appropriate surface treatment appears thus as a mandatory condition for designing of advanced devices. Ion implantation offers an unrivalled tool for tailoring of the surface properties, making possible to design new biocompatible materials characterized by superior mechanical or biological properties. Such properties as: cell adhesion, wettability, hardness, wear resistance and friction are currently intensively investigated. Some of them, mainly those related to cell adhesion and mechanical properties, are presented in this paper. Special emphasis is given to problems of wettability and friction reduction of ceramics and polymers.

- by Jacek Jagielski and +1
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- Materials Engineering, Condensed Matter Physics, Cell Adhesion, Surface Coatings

Ceramics are widely used biomaterials in prosthetic dentistry due to their attractive clinical properties. They are aesthetically pleasing with their color, shade and luster, and they are chemically stable. The main constituents of dental ceramic are Si-based inorganic materials, such as feldspar, quartz, and silica. Traditional feldspar-based ceramics are also referred to as "Porcelain". The crucial difference between a regular ceramic and a dental ceramic is the proportion of feldspar, quartz, and silica contained in the ceramic. A dental ceramic is a multiphase system, i.e. it contains a dispersed crystalline phase surrounded by a continuous amorphous phase (a glassy phase). Modern dental ceramics contain a higher proportion of the crystalline phase that significantly improves the biomechanical properties of ceramics. Examples of these high crystalline ceramics include lithium disilicate and zirconia. Keywords Dental ceramics. Silicates. Silica. Porcelain. Fracture toughness. Ceramic materials. Zirconia 2 Clinical Applications Ceramics have three major indications in dentistry: a) ceramic-metal crowns and fixed partial dentures, b) allceramic restoration that consists of crowns, inlays, onlays, and veneers, short span anterior bridges, and c) ceramic

- by Jukka Matinlinna
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- Materials Science, Silicon, Bond Strength, Zirconia

Although electrical discharge machining is essentially a material removal process, efforts have been made in the recent past to use it as a surface treatment method. An additive powder in the dielectric medium affects the sparking action and helps in improving the surface properties. It may melt at the high temperature of the plasma channel and alloy with the machined surface under appropriate machining conditions. Breakdown of the hydrocarbon dielectric contributes carbon to the plasma channel. In this paper, changes in surface properties of oilhardening non-shrinkable die steel after machining with manganese powder suspended in kerosene dielectric medium have been investigated. Results show improvement in microhardness by 73%, and no microcracks on the machined surface. X-ray diffraction analysis of the machined surfaces reveals the transfer of manganese and carbon from the plasma channel in the form of manganese carbide. Quantitative analysis of chemical composition by optical emission spectrometer confirms significant increase in the percentages of manganese and carbon.

Surface modi®cations of two varieties of jute fabrics, i.e. hessian cloth (HC) and carpet backing cloth (CBC), involving dewaxing, alkali treatment, cyanoethylation and grafting, have been made with a view to their use as reinforcing agents in composites based on a biodegradable polymeric matrix, Biopol. The chemically treated fabrics are characterized by Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The eects of dierent ®bre surface treatments and amounts of fabrics on the performance of the resulting composites are investigated. Mechanical properties such as tensile strength, bending strength and impact strength increase in comparison to pure Biopol as a result of reinforcement with jute fabrics. More than 50% enhancement in tensile strength, 30% in bending strength and 90% in impact strength of the composites relative to pure Biopol sheets have been observed under the present experimental conditions. Scanning electron microscopy (SEM) investigations show that surface modi®cations improve the ®bre/matrix adhesion. From degradation studies we ®nd that after 150 days of compost burial more than 50% weight loss of the jute/Biopol composite occurs. #