Wear and corrosion interaction of AISI D2 in an acidic environment

The tribological, electrochemical and tribo-electrochemical behavior of bare AISI D2 was studied. The tribological aspects were tested by pin on disc with an aluminum oxide ball as counter body, the electrochemical tests were performed in an aqueous solution of citric acid and the tribo-electrochemical evaluation was through a combination of both tests. AISI D2 steel presented abrasive wear in dry and wet conditions, such type of wear occurred due to stick-slip motion, moreover, in wet conditions the alloy corroded at corrosion current values around 10-6 A/cm2.  The damage produced over the wear track was larger under wet conditions than for the dry conditions

Optical properties of nickel-incorporated amorphous carbon film deposited by femtosecond pulsed laser ablation

International audienceThe present study investigates the optical properties of Ni-incorporated amorphous carbon (a-C:Ni) films covering a wide range of Ni concentration from doping to alloys. The films are deposited by sequential femtosecond pulsed laser ablation of graphite and Ni targets. The optical properties are analyzed by means of the Maxwell-Garnett theory with separated metal and carbon phases. This analysis permits to investigate the change of the carbon phase with Ni concentration. It is shown that the microstructure of the carbon phase is affected by the Ni incorporation even at low Ni concentrations (1 at.%) where a local reorganization of the carbon matrix occurs affecting the aromatic clusters. At higher Ni concentrations the films become more disordered

Room temperature transparent conducting oxides based on zinc oxide thin films

Doped zinc oxide thin films are grown on glass substrate at room temperature under oxygen atmosphere, using pulsed laser deposition (PLD). O2 pressure below 1 Pa leads to conductive films. A careful characterization of the film stoichiometry and microstructure using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) concludes on a decrease in crystallinity with Al and Ga additions (≤3%). The progressive loss of the (0 0 2) orientation is associated with a variation of the c parameter value as a function of the film thickness and substrate nature. ZnO:Al and ZnO:Ga thin films show a high optical transmittance (>80%) with an increase in band gap from 3.27 eV (pure ZnO) to 3.88 eV and 3.61 eV for Al and Ga doping, respectively. Optical carrier concentration, optical mobility and optical resistivity are deduced from simulation of the optical data

Structural and optical properties of Pb2KNb5O15 and GdK2Nb5O15 tungsten bronze thin films grown by pulsed laser deposition

International audienceLead potassium niobate Pb2KNb5O15 (PKN) and gadolinium potassium niobate GdK2Nb5O15 (GKN) thin films were grown on (001) MgO single crystal substrates using pulsed laser deposition technique. PKN and GKN thin films were characterized by X-ray diffraction and their linear optical properties were determined. The out-of-plane orientation of PKN thin film depends on the oxygen pressure used during the growth process: [001] for low pressure and [530] for high pressure. In contrast, GKN thin film is oriented [001] and is less sensitive to pressure. PKN and GKN thin films were found transparent and their refractive index quite similar to that reported on TTB-type ferroelectric oxides. GKN film exhibits high bandgap compared to the PKN film. (C) 2017 Elsevier B.V. All rights reserved

Wavelength Dependent Remote Power Supply for Shape Memory Alloy

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REALIZATION AND CHARACTERIZATION OF A NEW ORGANIC THIN FILM SEMICONDUCTOR

International audienceThe main objective of this paper is the realization and characterization of a new organic thin film semiconductor material through the use of an ideal mixture of Acetaminophen/Curcumin utilizing several characterization techniques. From optical analysis, we can conclude that our semiconductor material is comparable and shows good concurrency to the semiconductors applied in technologic applications. In fact, the analysis of the optical measurement (transmittance T) conducting to the optical energy bandgap, E-g, it was found the optical bandgap is around to 2.6 +/- 0.02 eV. In addition, by using the Wemple Didominico model it was found the dispersion energy E-D varied from 5 eV to 7 eV, the average bandgap E-M separated the center of both bands occupied and unoccupied is around 4.5 eV and the static refractive index n(0) varies from 1.3 to 2 and it dependent on the compactness and transparency of the material

Optical, electrical and structural investigations of nanostructured coatings of metal-incorporated amorphous carbon

The structure and physical properties of nano-structured metal (nickel and tantalum) incorporated amorphous carbon (a-C:Ni and a-C:Ta) thin films deposited by femtosecond pulsed laser deposition (PLD) have been investigated. Various complementary film characterizations, including atomic force microscopy (AFM), Fourier-transform infrared spectroscopy have been used to determine the nanostructure of the a-C :Ni and a-C :Ta films, with a metal concentration range within 1% and 15 at.%. The electronic and optical properties have been also investigated in order to evaluate the potentialities of the coatings consisting in metallic nodules embedded in an amorphous carbonaceous matrix. The influence of the metal nature and concentration on the structure and properties of the films has been highlighted. The ability of femtosecond pulsed laser deposition to synthesize nanocomposite carbon-based films with tailored structures and properties is discussed

Electromagnetic Digital Microactuators Remote Control by a Parallel Dual Wavelength Optical Communication System

International audienceIn this paper, a parallel dual wavelength optical communication channel is presented. A custom optical sensor based on a double Fabry-Perot structure is described. It allows the system to instantaneously demultiplex the incident wavelengths as well as offers noise rejection, such as ambient light. It allows sending two bits in only one pulse of light. Contrary to other optical approaches, the presented approach differs in that it uses a wide optical spectrum and only inexpensive electronics. The usefulness of this free space, point-to-point, communication channel is demonstrated in the remote control of an electromagnetic digital microactuator. Thanks to a proper algorithm in the receiver, the proposed system is able to control all the degrees of freedom of the microactuator with a movement for every pulse of light

Synthesis and properties of Bi5Nb3O15 thin films prepared by dual co-sputtering

International audienceBismuth-based oxides have gained attention because of their particular electronic configuration that enhances the mobility of photogenerated carriers. In this work, we focused on the synthesis, and the evaluation of the physical and photocatalytic properties of Bi5Nb3O15 films. Bismuth niobate films were deposited by dual magnetron co-sputtering, starting from Bi2O3 and Nb independently driven targets. Although the substrates were heated at 150 degrees C during the deposition, the films were amorphous; therefore, they were annealed at 600 degrees C in air for 2 h to obtain the nanocrystalline Bi5Nb3O15 orthorhombic phase. The Bi5Nb3O15 compound is an interesting material for applications in microelectronics due to its high-k dielectric value at the radiofrequency range; another possible and reported application is as photocatalyst for degradation of organic pollutants and water splitting processes. The films structure was confirmed by X-ray diffraction (theta-2 theta and in-plane modes). The Raman and infrared spectra were measured and compared with calculated vibrational modes since they have not been reported in the past. The optical properties (refractive index, extinction and absorption coefficients) of the Bi5Nb3O15 films were estimated using UV-VIS reflectance and transmittance spectroscopy. The optical band gap was estimated assuming an indirect fundamental inter-band transition at 3.25 eV. The prospective to use the Bi5Nb3O15 films as a photocatalyst was evaluated through the measurement of the photo-discoloration of indigo carmine (IC) dye solutions (5 ppm) under UV light irradiation at three pHs: 3.5, 7 and 11. The results showed a decrease in the absorbance spectrum of the IC solution as a function of irradiation time only at acidic pH where almost 100% of degradation was achieved at 270 min; this behavior is probably due to the increment of the adsorption of IC molecules on the positively charged surface. A similar response was observed after 5 cycles without any structural change of the films. (C) 2016 Elsevier B.V. All rights reserved