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Showing papers by "National Aerospace Laboratories published in 2017"


Journal ArticleDOI
TL;DR: In this paper, the potential of polymer and ceramic matrix composites for aerospace/space vehicle applications is discussed and the properties of resulting nanocomposite material with its disadvantages like cost and processing difficulties are discussed.
Abstract: This paper reviews the potential of polymer and ceramic matrix composites for aerospace/space vehicle applications. Special, unique and multifunctional properties arising due to the dispersion of nanoparticles in ceramic and metal matrix are briefly discussed followed by a classification of resulting aerospace applications. The paper presents polymer matrix composites comprising majority of aerospace applications in structures, coating, tribology, structural health monitoring, electromagnetic shielding and shape memory applications. The capabilities of the ceramic matrix nanocomposites to providing the electromagnetic shielding for aircrafts and better tribological properties to suit space environments are discussed. Structural health monitoring capability of ceramic matrix nanocomposite is also discussed. The properties of resulting nanocomposite material with its disadvantages like cost and processing difficulties are discussed. The paper concludes after the discussion of the possible future perspectives and challenges in implementation and further development of polymer and ceramic nanocomposite materials.

146 citations


Journal ArticleDOI
TL;DR: In this article, the authors have described different types of solar absorber coatings with particular emphasis on dielectric-metal-dielectric (DMD) based absorber coating.
Abstract: The effective use of solar energy has become significantly important due to unnatural weather changes and fossil fuel exhaustion Concentrating Solar Power (CSP) technology is a promising approach to harvest solar energy in the form of heat using solar selective absorber coating These coatings are expected to absorb maximum incoming solar radiation (α ≥ 095) and prevent loss of the absorbed energy as infrared radiation (e ≤ 005) Efficiency of the absorber coating can be evaluated by a metric called “Solar selectivity (α/e)” In recent years, a number of attempts have been made to achieve remarkable selective property and high temperature stability of the absorber coating using the concept of Surface Plasma Polaritons (SPPs) The SPPs have the capability to capture solar energy by confining electromagnetic field at the metal-dielectric interface Solar absorption, can be maximized by tailoring the optical constants of the metal and dielectric In this review, we have described different types of solar absorber coatings with particular emphasis on dielectric-metal-dielectric (DMD) -based absorber coatings We have presented a brief theoretical overview to comprehend physics of DMD coatings This review additionally highlights some of the case studies based on the DMD -based absorber coatings with the high temperature stability and their importance in the context of CSP technologies

103 citations


Journal ArticleDOI
TL;DR: In this paper, the authors reported the synthesis of nanostructured porous hollow nickel telluride nanosheets and their use as bifunctional electrocatalyst towards hydrogen and oxygen evolution reaction.

80 citations


Journal ArticleDOI
TL;DR: In this article, an optimized ITO/Ag/ITO (IAI) multilayer coating was designed for spectral beam splitter applications and these coatings were deposited on glass substrates by magnetron sputtering method.

73 citations


Journal ArticleDOI
TL;DR: In this article, two series of Fe-and Cr-doped Co3O4 catalysts were prepared by a single-step solution combustion technique, and the catalytic activity of new materials for low-temperature CO oxidation was correlated to the nature of the dopant.
Abstract: Co3O4 with a spinel structure shows unique activity for CO oxidation at low temperature under dry conditions; however the active surface is not very stable. In this study, two series of Fe- and Cr-doped Co3O4 catalysts were prepared by a single-step solution combustion technique. Fe was chosen because of its redox activity corresponding to the Fe2+/Fe3+ redox couple and compared to Cr, which is mainly stable in the Cr3+ state. The catalytic activity of new materials for low-temperature CO oxidation was correlated to the nature of the dopant. As a function of dopant concentration, the temperature corresponding to the 50% CO conversion (T50) demonstrated significant differences. The maximal activity was achieved for 15% Fe-doped Co3O4 with T50 of −85 °C and remained almost constant up to 25% Fe. In the case of Cr, the activity was observed to be maximum for 7% of Cr with T50 of −42 °C and significantly decreased for higher Cr loadings. Similarly, there was a contrasting behavior in catalyst stability too. 1...

64 citations


Journal ArticleDOI
TL;DR: In this paper, the self-healing property of the coating is investigated experimentally by electrochemical impedance spectroscopy and exfoliation test, and the results confirm that coatings containing 0.005 M cerium nitrate inhibitor offers superior protection to the surface.
Abstract: Cerium nitrate added silica-alumina hybrid sol-gel coatings have been explored for the corrosion protection of AA2024-T3. The self-healing property of the coating is investigated experimentally by electrochemical impedance spectroscopy and exfoliation test. The results confirm that coatings containing 0.005 M cerium nitrate inhibitor offers superior protection to the surface. Increase in the surface concentration of Ce species in the corrosion tested coating, as evaluated from X-ray photoelectron spectroscopy (XPS) studies, provides a strong evidence for the outward migration of cerium ions from the coating. Improved corrosion protection observed is attributed to the combined effect of the stable barrier nature of the coating and the corrosion inhibiting nature of Ce3 + ions.

56 citations


Journal ArticleDOI
TL;DR: In this article, the machining characteristics and machinability of a nickel-based superalloy were investigated using uncoated and TiAlN-coated tungsten carbide micro-end mills.
Abstract: We report the machining characteristics and machinability of a nickel based superalloy in this study. A micro-milling operation is loaded on Nimonic 75 using uncoated and TiAlN coated tungsten carbide micro-end mills. A full factorial design of experiments was devised to optimize the machining conditions to reduce the flank wear on the tool surface. The optimized machining conditions for uncoated micro-tools were found to be a cutting speed ( v c ) of 13 m/min and a feed rate ( f z ) of 6 mm/min. Following this, the tools were coated with TiAlN using a semi-industrial four-cathode reactive pulsed direct current unbalanced magnetron sputtering system. Further experiments were then performed using these optimized machining conditions using both uncoated and TiAlN coated micro-tools in order to ascertain the tool wear and surface integrity. The change in geometry of the machined slot was estimated based on the variation in tool radius of the micro-end mill with progression of the operation. A direct comparison was made between the results observed using both uncoated and TiAlN coated tungsten carbide to illustrate the effect of the nanocomposite TiAlN coating. It was seen that TiAlN coated micro-tools exhibited a superior performance as compared to the uncoated ones with respect to tool life and micro-burr formation.

54 citations


Journal ArticleDOI
TL;DR: The literature is filled with works done by researchers working in this domain this paper, and a significant contribution comes from the works which have been published during the period 1998-2014, which have primarily been on conventional and non-conventional micromachining techniques.
Abstract: The concept of miniaturizing machine tools has received a strong interest in the research community due to their ability to fabricate intricate components. Lower power consumption, higher productivity rate, and smaller sizes of work stations have enabled microscale machining operations to acquire an edge over other fabrication techniques in various applications such as aerospace, instrumentation, automotive, biomedical, etc. The literature is filled with works done by researchers working in this domain. A significant contribution comes from the works which have been published during the period 1998–2014. The focus of these studies has primarily been on conventional and nonconventional micromachining techniques. Since nonconventional machining operations such as microelectrical discharge machining, laser machining, etc., are not compatible with traditional workpiece materials, conventional micromachining techniques such as micromilling and microdrilling are generally used. However, as of today, the...

50 citations


Journal ArticleDOI
TL;DR: In this paper, the authors proposed a graded dielectric inhomogeneous streamlined radome for airborne applications, which is an excellent choice for airborne application as compared to airborne radomes based on conventional constant thickness radome designs and variable thickness VTR designs.
Abstract: Streamlined nosecone radomes for airborne applications have to cater to high-end electromagnetic (EM) performance requirements of fire control radar antenna system. In this regard, the EM performance analysis of an ogival radome based on novel graded dielectric inhomogeneous wall structure is presented. The radome wall considered here consists of seven dielectric layers cascaded in such a way that the middle layer has maximum dielectric parameters (dielectric constant and electric loss tangent) and on either side, dielectric parameters of the layers decrease in a graded (or stepwise) manner. Further, the outer surface of the radome wall is coated with an antistatic and antierosion radome paint. The EM performance parameters of the radome enclosing an X-band slotted waveguide planar array antenna (center frequency: 10 GHz; bandwidth: 1 GHz) are computed based on 3-D ray tracing in conjunction with aperture integration method. The study shows that the proposed graded dielectric inhomogeneous streamlined radome is an excellent choice for airborne applications as compared to airborne radomes based on conventional constant thickness radome designs and variable thickness radome (VTR) designs. Further, it circumvents the constraints on fabrication that occur in streamlined VTR designs.

39 citations


Journal ArticleDOI
TL;DR: In this paper, a transparent and conducting ITO/Ag/ITO (IAI) multilayer coatings were deposited on glass and flexible fluorinated ethylene propylene (FEP) substrates by reactive sputtering using metallic In:Sn (90%:10%) and Ag targets at room temperature.

36 citations


Journal ArticleDOI
25 May 2017
TL;DR: Electrochemical impedance spectroscopy reveals that the LZO coating plays a vital role in stabilizing the interface between the electrode and electrolyte during cycling; thus, it alleviates material degradation and voltage fading and ameliorates the electrochemical performance.
Abstract: In the quest to tackle the issue of surface degradation and voltage decay associated with Li-rich phases, Li-ion conductive Li2ZrO3 (LZO) is coated on Li1.2Ni0.13Mn0.54Co0.13O2 (LNMC) by a simple wet chemical process. The LZO phase coated on LNMC, with a thickness of about 10 nm, provides a structural integrity and facilitates the ion pathways throughout the charge–discharge process, which results in significant improvement of the electrochemical performances. The surface-modified cathode material exhibits a reversible capacity of 225 mA h g–1 (at C/5 rate) and retains 85% of the initial capacity after 100 cycles. Whereas, the uncoated pristine sample shows a capacity of 234 mA h g–1 and retains only 57% of the initial capacity under identical conditions. Electrochemical impedance spectroscopy reveals that the LZO coating plays a vital role in stabilizing the interface between the electrode and electrolyte during cycling; thus, it alleviates material degradation and voltage fading and ameliorates the elec...

Journal ArticleDOI
TL;DR: In this article, the vibro-acoustic modeling and analysis of sandwich plates with metal-ceramic and functionally graded core was performed using a simplified first-order shear deformation theory and elemental radiator approach, where the material properties of the core were assumed to vary according to a power law distribution of the volume fraction of the constituents.
Abstract: This paper presents the vibro-acoustic modeling and analysis of sandwich plateswith metal–ceramic functionally graded (FG) core using a simplified first-order shear deformation theory and elemental radiator approach. A simply supported rectangular plate having functionally graded core, metal and ceramic facesheets is considered with aluminum as metal and alumina as ceramic. The material properties of the core are assumed to vary according to a power law distribution of the volume fraction of the constituents. The sound radiation due to point load and uniformly distributed load is computed by numerically solving the Rayleigh integral. The effective material properties of the sandwich plate are presented as a function of core thickness. The vibration parameters in terms of natural frequencies, plate displacement and velocity, and acoustic parameters such as radiated sound power level, radiated sound pressure level and radiation efficiency are computed for various values of the power law index. A comprehensive study of the influence of core thickness on vibro-acoustic performance is presented in terms of mean-squared velocity and overall sound power level. It is found that, for the plate being considered, the sound power level increases with increase in the power law index of the core at lower frequency segment. Increased vibro-acoustic response is observed in the high-frequency band for ceramic-rich FG core and in the low-frequency band for metal-rich FG core, respectively. A sandwich plate with metal-rich FG core configuration has shown improved flexural stiffness, compared to an FG plate with no significant rise in overall radiated sound. It is possible with this analysis to suitably tailor and optimize the sandwich FG plates for multifunctional performance and desired vibro-acoustic interaction.

Journal ArticleDOI
TL;DR: In this paper, a solution precursor plasma spray and suspension plasma spray (SPS) processes were compared to obtain the phase and morphology of hydroxyapatite (HAp) coatings on Ti-6Al-4V alloy.

Journal ArticleDOI
TL;DR: In this article, an alumina reinforced with zirconia viz., 0, 3, and 8mol% yttria doped (i.e., ZrO2, 3YSZ, 8YSZ), and 4wt% carbon nanotube (CNT) is coated on Inconel 718 substrate by atmospheric plasma spraying (APS).
Abstract: In this work, alumina (Al2O3) reinforced with zirconia viz., 0, 3, and 8 mol% yttria doped (i.e., ZrO2, 3YSZ, and 8YSZ), and 4 wt% carbon nanotube (CNT) are coated on Inconel 718 substrate by atmospheric plasma spraying (APS). Reinforcement by CNT and 3YSZ has led to a substantial enhancement in the fracture toughness from 3.89 MPa m1/2 (for Al2O3) to 5.90 MPa m1/2 in the reinforced composite. It is observed that CNT has contributed ∼5–12% toughness enhancement, whereas ∼15% contribution to toughening is obtained via tetragonal to monoclinic (t→m) transformation of zirconia. Moreover, CNTs not only assist the t→m transformation but also enhance the toughness value of Al2O3-based thermal barrier coatings (TBC) near to its upper theoretical bound estimated using modified fractal model. Moreover, the effective thermal conductivity is estimated using modified theoretical models embracing the aligning factor of CNT in APS coatings, which unequivocally confirms the superiority of Al2O3 reinforced with 3YSZ and CNT as a potential TBC.

Journal ArticleDOI
TL;DR: A combination of plasmaenhanced chemical vapor deposition and magnetron sputtering techniques has been employed to deposit chromium-doped diamond-like carbon (DLC) coatings on stainless steel, silicon and glass substrates.
Abstract: A combination of plasma-enhanced chemical vapor deposition and magnetron sputtering techniques has been employed to deposit chromium-doped diamond-like carbon (DLC) coatings on stainless steel, silicon and glass substrates. The concentrations of Cr in the coatings are varied by changing the parameters of the bipolar pulsed power supply and the argon/acetylene gas composition. The coatings have been studied for composition, morphology, surface nature, nanohardness, corrosion resistance and wear resistance properties. The changes in I D /I G ratio with Cr concentrations have been obtained from Raman spectroscopy studies. Ratio decreases with an increase in Cr concentration, and it has been found to increase at higher Cr concentration, indicating the disorder in the coating. Carbide is formed in Cr-doped DLC coatings as observed from XPS studies. There is a decrease in sp 3/sp 2 ratios with an increase in Cr concentration, and it increases again at higher Cr concentration. Nanohardness studies show no clear dependence of hardness on Cr concentration. DLC coatings with lower Cr contents have demonstrated better corrosion resistance with better passive behavior in 3.5% NaCl solution, and corrosion potential is observed to move toward nobler (more positive) values. A low coefficient of friction (0.15) at different loads is observed from reciprocating wear studies. Lower wear volume is found at all loads on the Cr-doped DLC coatings. Wear mechanism changes from abrasive wear on the substrate to adhesive wear on the coating.

Journal ArticleDOI
TL;DR: In this paper, an experimental investigation was conducted to assess the effectiveness of five microvortex generator configurations in controlling an incident shock-induced separation associated with a 14-degree separation.
Abstract: An experimental investigation was conducted to assess the effectiveness of five microvortex generator configurations in controlling an incident shock-induced separation associated with a 14 deg sho

Journal ArticleDOI
TL;DR: In this article, the authors demonstrate the ability of functionalized chopped carbon fibers (CCFs) chosen from industrial waste to improve the thermo-mechanical properties of CCFs/epoxy composites.
Abstract: This study demonstrates the ability of functionalized chopped carbon fibers (CCFs) chosen from industrial waste to improve the thermo-mechanical properties of CCFs/epoxy composites. The defect sites onto the CCFs were created by their oxidation and the oxidized CCFs were covalently linked with siloxane functional groups to conceal their defects. The surface functionalization of CCFs was characterized by a simple chemical route, FTIR and TGA analysis, respectively. The surface morphology of functionalized CCFs showed the generation of highly dense networked globules. Epoxy composites filled with 0.5 wt% of siloxane attached CCFs (S-CCFs) showed a tremendous enhancement in storage modulus (∼376%) without sacrificing their thermal stability. Furthermore, the S-CCFs reinforced epoxy composites demonstrate a significant improvement in the tensile and fracture properties. Such enhancement in the mechanical properties can open up the scope for the utilization of CCFs as a potential cost-effective candidate for high-performance next generation structural composites.

Journal ArticleDOI
TL;DR: In this paper, a spectrally selective tandem absorber was used for solar thermal power generation applications, which achieved a solar absorptance of 0.960 at 82°C and an emittance of 0.,061 at 80°C, measured using solar spectrum reflectometer and emissometer.

Journal ArticleDOI
TL;DR: In this article, an EM (electromagnetic) design of low observable antenna using active hybrid-element frequency selective surface (FSS) as ground plane for stealth applications is presented.
Abstract: A novel EM (electromagnetic) design of low observable antenna using active hybrid-element frequency selective surface (FSS) as ground plane is presented in this paper for stealth applications. The EM characteristics of active hybrid-element FSS structure are reconfigured from reflecting mode to transmitting mode and vice versa by switching ON and OFF the PIN diode at 10 GHz. In ON state of diode (reflection mode), the FSS structure shows extremely less transmission ( 2 ) as compared to conventional MPA. Finally, a prototype active FSS-based antenna is fabricated and measured for proof-of-the concept.

Journal ArticleDOI
TL;DR: In this paper, the wear condition on the micro-tool cutting edge, surface roughness of machined holes, and hole diameter analysis in micro-drilling of Nimonic 80A, using two types of microdrills (uncoated and TiAlN coated) with 0.79 mm diameter.
Abstract: Micro-drilling is a complex mechanical machining process. Micro-drilling experiences an early tool damage which is a major drawback for nickel-based superalloy. This paper examines the wear condition on the micro-tool cutting edge, surface roughness of machined holes, and hole diameter analysis in micro-drilling of Nimonic 80A, using two types of micro-drills (uncoated and TiAlN coated) with 0.79 mm diameter. Micro-drilling tests, using cutting speed (Vc), feed rate (fz), and the micro-drill diameter as experimental parameters were carried out to bring out the best optimized machining conditions in micro-drilling of Nimonic 80A. Wear on the tool cutting edge and burr height occurring at the entrance of drilled holes were measured at constant period to give the lastingness of micro-drill. Quality of holes were analyzed in terms of surface roughness inside the hole and the hole diameter after every five drilled holes. The result obtained from the above analysis showed that TiAlN-coated micro-drill p...

Journal ArticleDOI
TL;DR: In this paper, the aerodynamic performance of a typical UAV whose wings were modified to incorporate tubercles on the leading edge was investigated, and the results showed that the wing with tubercles significantly improved the aircraft's aerodynamic efficiency.

Journal ArticleDOI
TL;DR: In this paper, a micro arc oxidation (MAO) coating was developed as an interlayer for the electroless nickel (EN) top coat to improve the corrosion resistance of Mg alloy.
Abstract: Micro arc oxidation (MAO) coating was developed as an interlayer for the electroless nickel (EN) top coat to improve the corrosion resistance of Mg alloy. Prior to the electroless nickel deposition, oxide layer was activated by using NaBH4 solution as a replacement for conventional chromate and HF activation processes. EN coatings were prepared using the alkaline carbonate bath. As-prepared coatings were characterized for the surface morphology and composition using Field Emission Scanning Electron Microscopy (FESEM) attached with energy dispersive analysis of X-ray (EDX). Potentiodynamic polarization studies were carried out in non-deaerated 3.5% NaCI solution to find out the corrosion resistance of the coatings. The MAO coating showed porous morphology with micro cracks whereas, MAO/Ni-P coating exhibited dense nodular structure. The cross-Ni-P and MAO/Ni-P/Ni-W-P duplex al images showed good adhesion between MAO and Ni-P layers. This clearly indicates that the present activation process results in dense with uniform pores of MAO coating along with excellent bonding at the interface for Ni-P coat. The MAO/EN coating combination showed two orders improvements in corrosion resistance as compared with the substrate. (C) 2017 Published by Elsevier B.V.

Journal ArticleDOI
TL;DR: In this article, carbon fiber cloth, ZrB2, polycarbosilane (PCS), and Zr metal at 4 MPa and 1200 °C were prepared by hot pressing.

Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate a very simple and effective approach to improve the sensitivity and the low detection limit of cobalt phthalocyanine (CoPc) films towards the detection of chlorine by creating a porous nanostructured surface on a glass substrate via a vapor phase etching process.
Abstract: In this paper, we demonstrate a very simple and effective approach to improve the sensitivity and the low detection limit of cobalt phthalocyanine (CoPc) films towards the detection of chlorine by creating a porous nanostructured surface on a glass substrate via a vapor phase etching process. CoPc films grown on etched glass (CoPc-etched films) exhibited entirely different morphology as compared to CoPc films grown on plain glass (CoPc-plain films). For 60 nm thickness, randomly distributed CoPc nanostructures were grown on the etched surface, whereas the CoPc-plain film showed an elongated granular structure. For 250 ppb Cl2 exposure, the CoPc-etched film showed a response of ∼105%, which is ∼5 times higher than the CoPc-plain film (20%). In addition, it can detect Cl2 down to 100 ppb concentration; this low detection limit is superior to CoPc-plain film (250 ppb). The improved gas sensing property of CoPc-etched film is ascribed to the presence of more interaction sites for gas adsorption, which is confirmed by charge transport, X-ray photoelectron spectroscopy and Kelvin probe measurement. This novel approach of improving the sensitivity and low detection limit paves a new way for the application of surface etching in the gas sensing field of organic semiconductors.

Journal ArticleDOI
TL;DR: In this article, the growth of flower-like ferromagnetic Cu-doped ZnO (CZO) nanostructures using electrochemical deposition on FTO-coated glass substrates was reported.
Abstract: We report the growth of flower-like ferromagnetic Cu-doped ZnO (CZO) nanostructures using electrochemical deposition on FTO-coated glass substrates. X-ray photoelectron spectroscopy studies affirmed the presence of Cu in ZnO with an oxidation state of 2+. In order to find the optimized dopant concentration, different Cu dopant concentrations of 0.28, 0.30, 0.32, 0.35, 0.38, and 0.40 mM are applied and their magnetic, optical, and electrical properties are studied. Magnetic moment increased with the increasing dopant concentration up to 0.35 mM and then decreased with further increase in the concentration. Diamagnetic pure ZnO showed ferromagnetic nature even with a low doping concentration of 0.28 mM. Band gap increased with the increasing Cu concentration until a value of 0.35 mM and then remained the same for the higher dopant concentrations. It is ascribed to the Burstein–Moss effect. Defect-related broad photoluminescence (PL) peak is observed for the pure ZnO in the visible range. In contrast, Cu-doped samples showed a sharp and intense PL peak at 426 nm due to increased Zn interstitials. Kelvin probe measurements revealed that the Fermi level shifts toward the conduction band for the Cu-doped samples with respect to pure material. Electron transport mechanism in the samples is observed to be dominated by space charge-limited current and Schottky behavior with improved ideality factor up to 0.38 mM Cu.

Journal ArticleDOI
TL;DR: In this article, the Schottky diode-like behavior of SiNPLs has been studied over a broad temperature range 170-360 K. The SiNpls show a Schotty diodelike behavior at a temperature below 300 K and the rectification is more prominent at temperature > 210 K.
Abstract: Si nanopillars (SiNPLs) were fabricated using a novel vapor phase metal-assisted chemical etching (V-Mace) and nanosphere lithography. The temperature dependent current–voltage (I–V) characteristics have been studied over a broad temperature range 170–360 K. The SiNPLs show a Schottky diode-like behavior at a temperature below 300 K and the rectification (about two orders of magnitude) is more prominent at temperature < 210 K. The electrical properties are discussed in detail using Cheung’s and Norde methods, and the Schottky diode parameters, such as barrier height, ideality factor, series resistance, are carefully figured out and compared with different methods. Moreover, the light sensitivity of the SiNPLs has been studied using I–V characteristics in dark and under the illumination of white light and UV light. The SiNPLs show fast response to the white light and UV light (response time of 0.18 and 0.26 s) under reverse bias condition and the mechanism explained using band diagram. The ratio of photo-to-dark current shows a peak value of 9.8 and 6.9 for white light and UV light, respectively. The Si nanopillars exhibit reflectance < 4% over the wavelength region 250–800 nm with a minimum reflectance of 2.13% for the optimized sample. The superior light absorption of the SiNPLs induced fast response in the I–V characteristics under UV light and white light. The work function of the SiNPLs in dark and under illumination has been also studied using Kelvin probe to confirm the light sensitivity.

Journal ArticleDOI
TL;DR: In this article, a radio frequency magnetron sputtering technique has been used to deposit Cu-doped ZnS thin films on glass and n-type Si(100) substrates at room temperature.
Abstract: Radio frequency magnetron sputtering technique has been used to deposit Cu-doped ZnS thin films on glass and n-type Si(100) substrates at room temperature. Crystalline structure, surface morphology, and elemental oxidation states have been studied by X-ray diffraction, field emission scanning electron microscopy, atomic force microscopy, and X-ray photoelectron spectroscopy. Ultraviolet–visible spectroscopy has been employed to measure the transmittance, reflectance, and absorbance properties of coated films. The deposited thin films crystallize in zinc blende or sphalerite phases as proved by X-ray diffraction analysis. The intensity of diffraction peaks decreases with increasing the dopant concentrations. The predominant diffraction peak related to (111) plane of ZnS is observed at 28.52° along with other peaks. The peak positions are shifted to higher angles with an increase of Cu concentrations. X-ray photoelectron spectroscopy studies show that Cu is present in +1 oxidation state. Transmittance, reflectance, and absorbance properties of the deposited films have a slight variation with dopant concentrations. Copyright © 2016 John Wiley & Sons, Ltd.

Journal ArticleDOI
TL;DR: In this paper, the authors quantified the delamination energy of reduced graphene oxide on soda lime glass by using nanoscratch technique and showed an inverse behavior of energy with temperature and treatment time, which could be correlated with the removal of oxygen functional groups.

Journal ArticleDOI
TL;DR: In this article, the electron paramagnetic resonance (EPR) spectra of vanadyl ions in the glasses exhibit a hyperfine structure and an increase in the ratio of Delta g(parallel to)/Delta g(perpendicular to) with an increase of V2O5 content shows that the tetragonal nature of the V4+O6 complex is enhanced.

Journal ArticleDOI
TL;DR: In this article, four different cases of specimens with embedded gaps in plies at multiple locations are under consideration and the optical images of cut specimens both longitudinal and transverse of all four cases are used for creating 3-D finite element models with ply waviness to compare their behavior with baseline reference specimens.