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Materials Science, Surfaces, Coatings & Films; expired drug; corrosion inhibitor; potentiodynamic polarization; electrochemical impedance spectroscopy; AFM
Online: 17 October 2017 (04:18:30 CEST)
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Our study aims to implement a strategy to reduce the carbon steel corrosion rate in sulfuric acid solution, using an expired drug with adsorption affinity on the metal surface. To investigate the corrosion protection efficiency of an environmental friendly inhibitor, namely neomycin sulfate (NMS), the electrochemical measurements were applied on carbon steel immersed in 1.0 M H2SO4 solution with and without NMS. The protective layer formed on the steel surface was studied by atomic force microscopy (AFM). The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) showed that the presence of the neomycin sulfate in acid solution leads to the decrease in corrosion current density (icorr) and the increase of polarization resistance (Rp). The mixed mechanism between physical and chemical adsorption of NMS molecules on the steel surface was proposed according to the Langmuir adsorption isotherm. The Atomic Force Microscopy (AFM) indicated that the NMS molecules contributed to a protective layer formation by their adsorption on the steel surface. The AFM parameters such as: root-mean-square roughness (Rq); average roughness (Ra) and maximum peak to valley height (Rp-v) revealed that in the presence of NMS a smoother surface of carbon steel was obtained, compared to the steel surface corroded in sulfuric acid blank solution.
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Materials Science, Surfaces, Coatings & Films; X-ray diffraction imaging; Raman spectroscopy; indentation geometry; plastic deformation; crack generation; plastic deformation strain imaging
Online: 10 October 2017 (11:46:27 CEST)
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The crack geometry and associated strain field around Berkovich and Vickers indents on silicon have been studied by X-ray diffraction imaging and micro-Raman spectroscopy scanning. The techniques are complementary, the Raman data coming from within a few micrometers of the indentation, whereas the X-ray image probes the strain field at a distance of typically tens of micrometers. For example, Raman data provides an explanation for the central contrast feature in the X-ray images of an indent. Strain relaxation from breakout and high temperature annealing are examined and it is demonstrated that millimeter length cracks, similar to those produced by mechanical damage from misaligned handling tools, can be generated in a controlled fashion by indentation within 75 micrometers of the bevel edge of 200mm diameter wafers.
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Materials Science, Surfaces, Coatings & Films; BaxSr1-xTiO3 films; boltzmann modelling; optical band gap; deposition rate; stoichiometric content
Online: 9 October 2017 (05:20:59 CEST)
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Thin films (100-400 nm) of BaxSr1-xTiO3 (0≤x≤1) deposited in RF-magnetron co-sputtering equipment are presented in this research work. The change of deposition rate, gap energy, and resistivity as a function of temperature- applied power change in the growth parameters was studied through the ISO colour-code lines constructed with MATLAB: By analysing the trend information and take into account the influence of the calculated "x" parameter with the Boltzmann profile fitting is proposed a method to allow a controlled set up of the RF-magnetron co-sputtering system and predict the Eg and resistivity values in the BaxSr1-xTiO3 solid solution with 0≤x≤1 for amorphous and crystalline phases. Also, a versatile tool to optimise the deposition process and material properties.
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Materials Science, Surfaces, Coatings & Films; phosphate coating; nitrate; nitrite; Zn-Ni coating; porosity
Online: 27 September 2017 (03:11:33 CEST)
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The aim of this study is to investigate the effect of nitrate and nitrite on the weight, morphology and electrochemical properties of phosphated Zn-%12Ni electrodeposit coatings. In order to investigate phase structure and surface morphology of samples, X-ray diffraction and scanning electron microscopy were employed. In order to measure corrosion resistance behavior of the coats, Potentiostat/Galvanostat test was used. The results showed that nitrite accelerator reduces coating weight and surface porosity simultaneously obtaining by phosphating solution. Furthermore, coatings which were obtained by the nitrite accelerator had a higher corrosion resistance than that of the nitrate accelerator.
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Materials Science, Surfaces, Coatings & Films; CAD/CAM implant abutments; zirconia; surface roughness; soft tissue adhesion; focus variation microscopy
Online: 20 September 2017 (05:28:24 CEST)
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Objective: CAD/CAM generated ceramic implant abutments have recently attracted interest due to their superior customization possibilities and aesthetic advantages. Despite their widespread clinical use, little information is currently available on their surface topography, however. The transmucosal portion of the abutment shoulder is of particular interest, as it ideally supports soft tissue but minimizes mechanical plaque retention. The aim of this in vitro study was to topographically characterize the trans- and subgingival roughness of CAD/CAM zirconia abutments from different manufacturers and compare them with zirconia stock abutments. Material and Method: The surface topography of eight CAD/CAM zirconia implant abutments (tests) and two prefabricated zirconia stock abutments (controls) was determined using focus variation microscopy. Two points on the abutment shoulder were subjected to profilometric examination. 2D and 3D parameters of roughness were obtained and compared. Results: The surface roughness of all the test abutments exceeded the recommended threshold of Ra = 0.2 µm and therefore exhibited an increased risk of mechanical plaque retention. Obvious differences in surface structure were apparent, allowing conclusions to be drawn about the manufacturing method and subsequent reworking processes. Conclusion: Manually reworking the trans- and submucosal area of the investigated CAD/CAM zirconia abutments appears necessary to fulfil the conditions for optimal surface topography. The Sa value as arithmetic mean, taking the maximum height (Sz value) and surface excess (Sdr) into account, is an essential parameter for assessing the surface topography of implant abutments.
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Materials Science, Surfaces, Coatings & Films; interfacial phase; interface model; displacement jump; boundary element method
Online: 15 September 2017 (11:52:35 CEST)
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Interface between matrix/coating or coating/coating in fact represents a very complicate thin interfacial layer. So interface model is necessary to avoid the difficulty on considering such a complicate thin layer in analysis. Classic interface model and cohesive model have been widely used in stress analysis of coating materials, though they cannot represent the effect of very thin interfacial layer accurately. A complete interface model has been deduced from the equivalent constitutive of interfacial layer in this paper. It is found that both classic interface model and cohesive model sometimes cannot give correct analysis results, while the complete interface model can always give a correct result. Moreover, the stress parallel to interface within the interfacial layer can also be analyzed by the new model. Besides, this model can also be used to describe the equivalent properties of interfacial layer, thereby, can provide a quantitative characterizing method for interfacial layer itself.
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Materials Science, Surfaces, Coatings & Films; amorphous oxide semiconductor (AOS); thin film transistor (TFT); nitrogen-doped amorphous InGaZnO (a-IGZO:N); nitrogen-doped amorphous InZnO (a-IZO:N); hetero-structure
Online: 8 September 2017 (09:54:19 CEST)
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The nitrogen-doped amorphous oxide semiconductor (AOS) thin film transistors (TFTs) with double-stacked channel layers (DSCL) were prepared and characterized. The DSCL structure composed of nitrogen-doped amorphous InGaZnO and InZnO films (a-IGZO:N/a-IZO:N or a-IZO:N/a-IGZO:N) made the corresponding TFT devices exhibit quite large field-effect mobility due to the existence of double conduction channels. Especially, the a-IZO:N/a-IGZO:N TFTs showed even better electrical performance (μFE = 15.0 cm2·V-1·s-1, SS = 0.5 V/dec, VTH = 1.5 V, ION/IOFF = 1.1×108) and stability (VTH shift of 1.5, -0.5, and -2.5 V for positive bias-stress, negative bias-stress and thermal stress tests, respectively) than the a-IGZO:N/a-IZO:N TFTs. Based on the X-ray photoemission spectroscopy measurements and energy band analysis, it was assumed that the optimized interface trap states, the less ambient gas adsorption, and the better suppression of oxygen vacancies in the a-IZO:N/a-IGZO:N hetero-structures might be responsible for the better behaviors of the corresponding TFTs.
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Materials Science, Surfaces, Coatings & Films; graphene oxide; porphyrin; nylon 66. coating, electrochemical techniques
Online: 5 September 2017 (05:12:26 CEST)
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Electrochemical impedance (EI) measurements were performed to evaluate the nylon 66/-tetra-(para-aminophenyl) porphyrin (H2T(p-NH2)PP)/graphene oxide (GO) film coating on stainless steel and compared to the nylon/H2T(p-NH2)PP and nylon/GO film samples using 1M H2SO4 as electrolyte. The nylon/H2T(p-NH2)PP and nylon/GO composite films showed high electrochemical impedance in the order of 109 ohm-cm2 and a system controlled by mass transfer, product of a diffusion process at low frequencies with a resistance up to 5 orders of magnitude, indicating the diffusion of protons through the coating and a decrease in the metal dissolution. Otherwise, the nylon/H2T(p-NH2)PP/GO film compound evaluated show good ionic conductivity and electrochemical stability in the acid environment, acting porphyrin as a catalyst to the passage of protons through the film, reducing its electrochemical impedance up to 7 orders of magnitude with respect to the compounds nylon/H2T(p-NH2)PP and nylon/GO. Likewise, good capacitance values are also shown by modifying the concentrations of porphyrin and GO reinforcing materials. These properties are important for technological applications, such as anticorrosion coating for bipolar plates or membrane in a fuel cell type PEM, super-capacitors, etc.
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Materials Science, Surfaces, Coatings & Films; 3-((2-chlorobenzylidene)amino)coumarin; corrosion inhibitor; damage reduction
Online: 7 August 2017 (10:51:42 CEST)
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New corrosion inhibitor derived from coumarin-3-amine namely 3-((2-chlorobenzylidene)amino)coumarin was synthesized and characterized by CHN elemental analysis in addition to Fourier transform infrared and nuclear magnetic resonance techniques. The anti-corrosion ability of 3-((2-chlorobenzylidene)amino)coumarin to inhibit the impacts of corrosion has been demonstrated and damage reduction of the mild steel also. 3-((2-chlorobenzylidene)amino)coumarin, has been employed as a good corrosion inhibitor for mild steel in HCL solution. The efficiency of the inhibition was figured according to weight loss method and it was 74.6%.
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Materials Science, Surfaces, Coatings & Films; corrosion inhibitor; coumarin; resonance
Online: 31 July 2017 (16:37:19 CEST)
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Corrosion inhibitors are the natural or synthetic compounds that have the ability to inhibit the average of corrosion and reduce the damage of the mild steel. Enormous organic inhibitors nowadays employed in the corrosion domain but excluded due to costly. Comparatively cheap, and stable organic compound, namely 3-((4-nitrobenzylidene)amino)coumarin, have been utilized as an excellent corrosion inhibitor in hydrochloric acid for mild steel. The inhibition efficiency has been figured regarding to weight loss method. The corrosion inhibitor was identified according to spectroscopic techniques namely Fourier transform infrared and nuclear magnetic resonance in addition to micro-elemental analysis. Inhibition efficiency for the studied inhibitor was 71.4% that, at the highest studied concentration.
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Materials Science, Surfaces, Coatings & Films; Ionic liquids; dicationic; imidazolium; poly(ethylene glycol); tribochemistry; mechanically stimulated gas emission mass-spectrometry
Online: 19 July 2017 (22:59:19 CEST)
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Dynamic tribochemical processes for dicationic ionic liquid containing a germinal imidazolium cation head groups bridged by a poly(ethylene glycol) and bis(trifluoromethylsulfonyl)imide anion were studied using time-resolved Mechanically Stimulated Gas Emission Mass-Spectrometry (MSGE-MS). In comparison with similar monocationic imidazolium ionic liquids with short alkylic or long polyether side chains the dicationic ionic liquid had lower coefficient of friction on Ti6Al4V alloy and smoother behaviour. The analysis of volatile decomposition products suggested multiple tribochemical reactions in which both anionic and cationic moieties are involved. Tribochemical degradation of cations was mainly through detachment of the side and bridging chains from the imidazolium head groups. Absence of volatile products containing nitrogen implies that imidazole group remained unchanged. Hydrogen and water desorption were attributed to the reactions of hydrogen fluoride being a product of anion degradation with titanium and titanium oxide.
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Materials Science, Surfaces, Coatings & Films; membranes; polymer solution; breath-figures; ordering; capillary cluster
Online: 30 June 2017 (11:05:45 CEST)
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The review is devoted to the physical, chemical and technological aspects of the breath-figures self-assembly process. Main stages of the process and the impact of the polymer architecture and physical parameters of the breath-figures self-assembly on the eventual pattern are covered. The review is focused on the hierarchy of spatial and temporal scales inherent for the breath-figures self-assembly. Multi-scale patterns arising from the process are addressed. The characteristic spatial lateral scales of patterns vary from nanometers to dozens of micrometers. The temporal scales of the process span from micro-seconds to seconds. The qualitative analysis performed in the paper demonstrates that the process is mainly governed by the interfacial phenomena, whereas the impact of inertia and gravity is negligible. Characterization and applications of polymer films manufactured with breath-figures self-assembly are discussed.
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Materials Science, Surfaces, Coatings & Films; Rare earth rich magnesium alloy, Plasma Electrolytic Oxidation, PEO, Microstructure, Fatigue
Online: 25 May 2017 (18:24:45 CEST)
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Rare earth rich magnesium alloys are used in aerospace and automotive fields because of their high specific strength and good castability. However, due to their low corrosion resistance, protective surface treatments, such as conversion coating or electroless plating are necessary, when they have to be used in humid or corrosive environments. The present study was aimed to evaluate the effect of Plasma Electrolytic Oxidation (PEO) and different surface roughness (Ra≈0.8 μm and Ra≈0.3 μm) on the rotating bending fatigue of an innovative Mg alloy, with a high content of Nd (up to 3.1 wt%) and Gd (up to 1.7 wt %). Fatigue tests revealed a 15% decrease in the fatigue strength of the PEO treated alloy (fatigue strength = 88 MPa) with respect to the bare alloy (fatigue strength = 103 MPa). The reduction of fatigue strength was mainly due to the residual tensile stresses induced by the PEO treatment. The effect of surface roughness on the bare alloy was, instead, negligible. The mechanisms of crack initiation were similar in the untreated and PEO treated alloy, with crack nucleation sites located in correspondence of large facets of the cleavage planes.
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Materials Science, Surfaces, Coatings & Films; polyester fabrics; surface modification; sulfuric acid; polypyrrole; deposition; conductivity
Online: 1 May 2017 (08:48:17 CEST)
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A simple and effective surface modification of polyester fabrics with sulfuric acid to improve the interfacial deposition of polypyrrole was presented in our work. A range of sulfuric acid concentrations were analyzed by studying water contact angle. Effect of sulfuric acid modification on the deposition of polypyrrole was investigated by sheet resistance and color depth of fabric samples. Polyester fabrics coated with polypyrrole layer were confirmed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), X-Ray diffraction spectra (XRD), Fourier transform infrared spectroscopy (FTIR). XPS showed that sulphur containing functional groups were obviously appeared on the polyester fiber surface after modification, which were advantageous to promote the deposition of polypyrrole onto polyester fabrics. The improved deposition increased electrical conductivity of fabric samples.
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Materials Science, Surfaces, Coatings & Films; electroluminescent; 3D-printing; rapid prototyping; light-emitting fibers; roll-to-roll process
Online: 1 May 2017 (07:25:50 CEST)
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There is a growing interest in fibers supporting optoelectrical properties for textile and wearable display applications. Solution-processed electroluminescent (EL) material systems can be continuously deposited onto fiber or yarn substrates in a roll-to-roll process, making it easy to scale manufacturing. It is important to have precise control over layer deposition to achieve uniform and reliable light emission from these EL fibers. Slot-die coating offers this control and increases the rate of EL fiber production. Here, we report a highly adaptable, cost-effective 3D printing model for developing slot dies used in automatic coating systems. The resulting slot-die coating system enables rapid, reliable production of alternating current powder-based EL (ACPEL) fibers and can be adapted for many material systems. The benefits of this system over dip-coating for roll-to-roll production of EL fibers are demonstrated in this work.
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Materials Science, Surfaces, Coatings & Films; biodegradable; Carboxymethyl cellulose (CMC); edible films; mechanical properties; sago starch
Online: 20 February 2017 (06:43:55 CET)
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Using biodegradable films is increasingly growing since they contain natural materials. In this study, sago starch and carboxymethyl Cellulose (CMC) were used in film preparation. Sago starch films with 0, 5, 10, 15 and 20% CMC concentrations were prepared using solvent casting method. The mechanical properties were determined according to standards of American Society for Testing and Materials. In mechanical test of the combined films, increased CMC concentration significantly (P<0.05) increased tensile strength and Young Modulus from 21.04 to 27.74MPa and from 1372.83 to 1842.87kg/m2, respectively, and percent elongation showed significant (P<0.05) reduction from 17.69 to 15.39. Considering biodegradability of the edible films and improvement of their mechanical properties by CMC, they can be utilized in different industries, particularly in food industry, as an edible coating for packaging food and agricultural products. With regard to its properties such as cost saving, biodegradability and mechanical properties when percentage of CMC increased can found a position among food packaging materials.
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René De La Barré,
Roland Bartmann,
Silvio Jurk,
Mathias Kuhlmey,
Bernd Duckstein,
Arno Seeboth,
Detlef Lötzsch,
Christian Rabe,
Peter Frach,
Hagen Bartsch,
Matthias Gittner,
Stefan Bruns,
Gerhard Schottner,
Johanna Fischer
Materials Science, Surfaces, Coatings & Films; fast switchable wavelength-selective elements, autostereoscopic image splitter, color filter barrier array, Fabry-Pérot color filter, on-off filter mode
Online: 1 February 2017 (16:52:44 CET)
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A time-sequential working, spatially multiplexed autostereoscopic 3D display design consisting of a fast switchable RGB-color filter array is presented. The wavelength-selective filter barrier emits the light from a display over a larger active area than common autostereoscopic barrier displays. An optical modelling of wavelength-selective barriers has been used for instance to calculate the light ray distribution properties of that arrangement. To find well working display designs, automated searches by simulation and computational evaluation has been proceeded. Wavelength-selective filter barrier arrangements exhibit characteristics different from common barrier displays with similar barrier pitch and ascent. In particular, these constructions show strong angular luminance dependency under barrier inclination specified by correspondent slant angle. In time-sequential implementation it is important to avoid that quick eye or eyelid movement lead to visible color artifacts. In the millisecond regime tunable liquid crystal Fabry-Pérot color filters for the colors red, green and blue are presented. They consist of a sub-micrometer thick nematic layer sandwiched between dielectric mirrors and ITO-electrodes. These cells shall switch narrow-banding light of red, green or blue. An array for a glasses-free 3D display has to be equipped with several thousand switchable filter elements having different color apertures. The newly introduced design is usable as a multi user display as well as a single user system with user adaptive control.
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Materials Science, Surfaces, Coatings & Films; Superhydrophobic; Water-repellent; Chemical etching; Self-cleaning; Anti-fogging
Online: 2 January 2017 (17:27:05 CET)
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Development of the self-cleaning and anti-fogging superhydrophobic coating for aluminum surfaces which is durable in the aggressive conditions has raised tremendous interest in materials science. In this work, by employing chemical etching technique with mixture of hydrochloric and nitric acid, followed by passivation with lauric acid, superhydrophobic aluminum surface was synthesized. The surface morphology analysis reveals the presence of rough microstructures on coated aluminium surface. Superhydrophobicity with water contact angle of 170 ± 3.9° and sliding angle of 4 ± 0.5° is achieved. Surface bounces off the high speed water jet, indicating excellent water-repellent nature of coating. It is also continuously floated on water surface for several weeks, showing excellent buoyancy nature. Additionally, coating maintains its superhydrophobicity after undergoing 100 cycles of adhesive tape peeling test. Its superhydrophobic nature withstands 90° and 180° bending, and repeated folding and de-folding. Coating exhibits the excellent self-cleaning property. In low temperature condensation test, almost no accumulation of water drops on the surface, showing the excellent anti-fogging property of coating. This approach can be applied to any size and shape of aluminium surface and hence has great industrial applications.
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Materials Science, Surfaces, Coatings & Films; chemical phosphate coating; EIS; nano TiO2; TAFEL
Online: 23 December 2016 (10:23:24 CET)
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The present study aims at deposition of zinc phosphate coatings with the incorporation of nano Titanium dioxide particles by chemical phosphating method. Zinc phosphate coatings were developed on low carbon steel by using nano TiO2 in the standard phosphating bath. The Coated low carbon steel samples were assessed for corrosion studies using electrochemical impedance spectroscopy and potentiodynamic polarisation techniques in 3.5% NaCl solution. Chemical composition of the coatings was analysed by energy dispersive X-ray spectroscopy (EDX). Significant variations in the coating weight, porosity and corrosion resistance were observed with the addition of nano TiO2 in the phosphating bath. Corrosion rate of nano TiO2 incorporated chemical phosphate coated samples was found to be 3.5 mpy which was 4 times less than the bare uncoated low carbon steel (~14 mpy). Electrochemical impedance spectroscopy studies revels in the reduction of porosity in nano TiO2 phosphate coated samples. It was found that nano TiO2 particles in the phosphating solution yielded phosphate coatings of higher coating weight, greater surface coverage and enhanced corrosion resistance than the normal zinc phosphate coatings (developed using normal phosphating bath).
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Materials Science, Surfaces, Coatings & Films; CuInSe2 electrodeposition; alkaline doping; current sensing atomic force microscopy
Online: 18 December 2016 (09:48:30 CET)
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The local electrical response in alkaline-doped CuInSe2 films prepared by single step electrodeposition onto Cu substrates was studied by current sensing atomic force microscopy. The CIS films were prepared from single baths containing the dopant ions (Li, Na, K or Cs) and were studied by X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy and photocurrent response. Increased crystallinity and surface texturing as the ion size increases was observed as well as enhanced photocurrent response in Cs doped CIS. Li and Na doped films have larger conductivity than the undoped film while the K and Cs doped samples display shorter currents and the current images indicate strong charge accumulation in the K and Cs doped films forming surface capacitors. Corrected CAFM IV curves were adjusted with Shockley equation.
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Materials Science, Surfaces, Coatings & Films; Cryogenic treatment; wear resistance; Raman intensity rate
Online: 7 December 2016 (11:13:10 CET)
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This study explored the effects of cryogenic treatment on the microstructure, hardness, and wear-resistance of diamond-like carbon (DLC) by cryogenically treating NAK 80 mold steel coated with DLC. Raman spectroscopy analyzed the structure of the DLC film. Nanoindenter analyzed the hardness and Young’s modulus of the film, and their relationship determined the wear resistance. Wear test assessed the wear rate and friction coefficient of the DLC film. The results showed that cryogenic treatment increased the rate of carbide precipitation and refined the grain structure. Raman spectroscopy indicated that the Raman intensity rate (ID/IG) of treated DLC films was smaller than those without cryogenic treatment. When the sp3 bond increased, the hardness and wear-resistance of the DLC film also increased.
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Materials Science, Surfaces, Coatings & Films; CO2 enhanced capture; SBA-15 habilitation for CO2 sorption; desilication; silanol functionalization; covalent coordinated CO2 deposition
Online: 29 September 2016 (12:38:24 CEST)
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Special preparation of SBA-15 materials has been carried out for creating adsorbents exhibiting an enhanced and selective adsorption toward CO2. This creation starts from an adequate conditioning of the silica surface, via a thermo-alkaline treatment to increase the population of silanol species on it. CO2 adsorption is only reasonably achieved when the SiO2 surface becomes aminated after put in contact with a solution of an amino alkoxide compound in the right solvent. Unfunctionalized and amine-functionalized substrates were characterized through X-ray diffraction, N2 sorption, Raman spectroscopy, electron microscopy, 29Si solid-state NMR, and NH3 thermal programmed desorption. These analyses proved that the thermo-alkaline procedure desilicates the substrate and eliminates the micropores (without affecting the SBA-15 capillaries), present in the original solid. NMR analysis confirms that the hydroxylated solid anchors more amino functionalizing molecules than the unhydroxylated material. The SBA-15 sample subjected to hydroxylation and amino- functionalization displays a high enthalpy of interaction, a reason why this solid is suitable for a strong deposition of CO2 but with the possibility of observing a low-pressure hysteresis phenomenon. Contrastingly, CH4 adsorption on amino-functionalized, hydroxylated SBA-15 substrates becomes almost 5 times lesser than the CO2 one, thus giving proof of their selectivity toward CO2.
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Materials Science, Surfaces, Coatings & Films; carbonyl iron; composites film; external magnetic field; microwave absorption properties
Online: 28 September 2016 (10:32:52 CEST)
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The carbonyl iron particles were dispersed in a polychloroprene rubber (CR) matrix under an external magnetic field for practical application as microwave absorption composites film. The film prepared under external magnetic field with a thickness of only 0.54 mm showed least reflection loss of -15.98 dB and the reflection loss value less than -10.0 dB over the frequency range of 11.4~14.8 GHz. In comparison with the microwave absorption properties of calculation by transmission line theory based on the tested relative complex permittivity and permeability and film prepared by general route without external magnetic field, the film made with external magnetic field exhibited more excellent microwave absorption properties, strongly depending on the increment of anisotropy and rearrangement of magnetic particles. The results indicated the composite film made under external magnetic field have excellent microwave absorption properties, which suggest that the composites thin film could be used as a thinner and lighter microwave absorber.
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Materials Science, Surfaces, Coatings & Films; nano-Au particles; NIPAAm hydrogel; plasma treatment; UV grafting
Online: 28 September 2016 (09:49:23 CEST)
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In this study, a new type of temperature sensor device was developed. The circular electrode of the thermal sensitive sensor was modified with TMT and O2 plasma to enhance the conductivity by forming a thin SnOxCy layer on the electrode surface. The Nano-Au particles were subjected to O2 plasma pretreatment to form peroxide groups on the surface. The thermally sensitive sensor was made by mixing the above-treated Nano-Au particles with N-isopropylacrylamide (NIPAAm) to form solution and then UV-induced grafting polymerization of the NIPAAm-containing solution onto the electrode substrate. The composite hydrogels on the electrode introduce thermo-sensitive polymeric surface films for temperature sensing. Using ambient environment resistance test to measure the resistance, the LCST (lower critical solution temperature) of Nano-Au (MUA) mixed with NIPAAm hydrogel was found to be 32 °C. At ambient temperatures higher than LCST, the electrode resistance decreases linearly.
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Materials Science, Surfaces, Coatings & Films; waterborne polyurethane; adhesive; lignin
Online: 9 August 2016 (14:53:10 CEST)
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A series of waterborne polyurethane (WBPU)/modified lignin amine (MLA) adhesives was prepared using modified lignin amine (MLA) as a chain extender by a prepolymer mixing process. A successful Mannich reaction was achieved during the synthesis of MLA by reacting lignin with bis(3-aminopropyl)amine. Higher tensile strength, Young’s modulus and thermal stability were recorded for WBPU/MLA adhesives with higher MLA contents. The WBPU/MLA adhesive materials were used to coat PVC substrates. The adhesive strength increased with increasing MLA content. More importantly, the MLA also enhanced the WBPU/MLA coating in terms of adhesive strength at moderately high temperatures as well as under natural weather exposed conditions. The adhesive strength was essentially unaffected with 6.48 mole% MLA in the WBPU/MLA coating after exposure to natural weather conditions for 180 days.