Papers by Keyword: Surfaces

Abstract: The aim of this paper is to describe the fracture behavior of composites reinforced with two layers of Alfa random. An alkaline treatment at 1, 5 and 10% for a period of 24 hours with NaOH solution was performed to improve the mechanical properties of Alfa fibers. The morphological and structural changes that occurred in fiber after treatment; and the effects of this treatment on the mechanical properties of composites were discussed and were supported by Scanning Electron Microscopy. Many aspects of studies reported in this paper are original, such as the strain energy release rate and intensity factor evaluation of Alfa composites.

Abstract: Stiff coating on the phase-separated soft polyurethane substrate under the compression deformation is investigated by the finite element modeling (FEM). External strain leads to the wrinkling of layer surface, which is characterized by a set of wavelengths and amplitudes. The influence of the thickness and stiffness of the layer, elastic modulus of the substrate on the structural-mechanical properties of the deformed surface is studied. The results of the model are in good accordance with the experiment (plasma immersion ion impanation of nitrogen ions into the polyurethane substrate) and allowed to estimate the modulus of the coating and the deformation of the surface.

Abstract: The characterization and properties of the HKT800 carbon fiber were performed, and results showed that the tensile strength, tensile modulus and tensile elongation of HKT800 carbon fiber reached 5.6 GPa, 290 GPa and 1.9 %, respectively. The Cv value of all index was less than 3 %, and there were a few HKT800 carbon fibers belong to the cashew type. Furthermore, the surface activity of 6 K carbon fibers was higher than that of the 12 K carbon fibers after the same surface treatment. It was found that the sizing agent existed on the surface of HKT800 carbon fiber was epoxy resin.

Abstract: Single phase CuO films have been successfully synthesized by thermal oxidation of cupper foil in air with water vapor. The structural and optical properties of CuO films were investigated. It is observed that the grain size increases with increasing the oxidation temperature. The optical band gap of CuO film is determined by the transmittance and reflectance spectra.

Abstract: The paper aims at studying the phenomenon of adhesion between the graphite pellicles deposited through electric discharges in pulse (EDI) with metal surfaces subjected to processing on the one hand and on the other hand the adhesion of this pellicle with a polyurethane adhesive. Experimental research has shown that, when the surfaces are not treated, the shear occurs in the adhesive, when the test pieces are covered with graphite pellicles the shear occurs on the surface that separates the pellicle from the adhesive. It has been stated experimentally that graphite pellicles deposited through electric discharges in pulse decrease the adhesion between the mating surfaces by at least 40% compared to the not treated surfaces.

Abstract: Conical arrays of polydimethyl siloxane were fabricated by duplicating the morphology of needle tips. The prepared cones have periodic order and regular shape, with the bottom diameter of about 80 μm and height of about 250 μm. Due to their special structure, the conical arrays of polydimethyl siloxane exhibited broadband anti-reflective property. Compared with smooth surface, they could reduce the reflection of incident electromagnetic wave at ultraviolet, visible and near-infrared region. The specular reflectance was lower than 0.75% in the range of 250-2600 nm. The prepared PDMS cones have potential to be applied for antireflective devices. The method was simple for mass production of PDMS cones at low cost.

Abstract: Iron-phthalocyanines (Fe-phthalocyanines) with different amounts of carboxyl groups were added into carboxymethylcellulose (CMC) cation exchange membrane to prepare the modified CMC/CS bipolar membranes (BPMs, CS: chitosan), which were characterized using electric universal testing machine, contact angle measurer and so on. Experimental results showed that the ion exchange capacity, hydrophilicity of CMC membrane and mechanical properties of the BPM notablely got better after Fe-phthalocyanines were added. Furthermore, a high charge density area formed in the interlayer of the BPM after modification, which sped up water dissociation and lowered the membrane impedance. At the current density of 60 mA cm^-2, the cell voltages of Fe₂Pc₂(COONa)₁₂-CMC/CS BPM, FePc (COONa)₈-CMC/CS BPM, FePc (COONa)₄-CMC/CS BPM and CMC/CS BPM were 5.6V, 6.2V, 6.5V and 8.9V respectively [here, Fe₂Pc₂(COONa)₁₂: planar binuclear iron (III) phthalocyanine; FePc (COONa)₈:iron (III) octocarboxyphthalocyanine; FePc (COONa)₄:iron (III) tetracarboxyphthalocyanine]. The cell voltage of Fe₂Pc₂(COONa)₁₂-CMC/CS BPM was the smallest.

Abstract: High quality cuprous oxide thin films with large grain size were grown by thermal oxidation of copper foil in water vapor with N₂ gas. It was found that in water vapor (111) oriented Cu₂O is preferentially formed, whereas mixtures of random oriented CuO and Cu₂O are formed when oxidized in air. The effects of the film oxidation method and heating temperature are investigated. In addition, the optical band gaps of cuprous oxide thin films have been determined by measuring the transmittance and reflectance spectra.

Abstract: Associating a perturbation term for the effective refractive index which may depend ontime or position we describe the extremal features for the surface plasmon fields propagating on aroughness metal surface. This representation allows us to interpret the surface optical field as ageodesic flow which in principle enables us to associate coherence features to plasmon modes andto analyze the stability of the surface fields under small perturbations of the refractive index.

Abstract: An important and basic issue of compound material surface analysis was raised in this paper, that was, the picking basic element which that material microstructures were well characterized according to the research subject of material. Here, the five kinds of basic element were proposed for picking, they were separately ellipse, regular triangle, rectangle, square and circle. At first, the counting methods and rules of area radio base on elements and pictures, and the formula of the merging difference was introduced, then block experiment design in modern statistics was used to pick among the five elements. At last, through experiment and analysis, the result of picking was that ellipse element was most appropriate one among five elements. Meanwhile, it was pointed in this paper with regard to the area radio of picture based on element that the approaching extent of the ellipse was most suitable among five elements.