Papers by Keyword: Layers

Abstract: The present study has been conducted in order to obtain iron nitrides layer on AISI4140 steel by using plasma nitriding treatment. As one of several parameters of this process, the nitrogen rate ranging from 10 to 70% with a step of 20% was chosen. The structure, the morphology, the thickness and the hardness of iron nitrides layer were investigated. As a result, the improvement of surface hardness of nitrided steel was identified related with the increase of compound layer thickness due to the increase of activation rate. The steel substrate treated at high activation rate presents hardness 3 times higher than that of untreated steel.

Abstract: Engineering Science Based on Modelling and Simulation (M & S) is defined as the discipline that provides the scientific and mathematical basis for simulation of engineering systems. These systems range from microelectronic devices to automobiles, aircraft, and even oilfield and city infrastructure. In a word, M & S combines knowledge and techniques in the fields of traditional engineering - electrical, mechanical, civil, chemical, aerospace, nuclear, biomedical and materials science - with the knowledge and techniques of fields such as computer science, mathematics and physics, and social sciences. One of the problems that arise during solar cell operation is that of heating them because of permanent solar radiation. Since the layers of which they are made are very small and thick it is almost impossible to experimentally determine the temperature in each layer. In this sense, the finite element method comes and provides a very good prediction and gives results impossible to obtain by other methods. This article models and then simulates the thermal composition of two types of solar cells, one of them having an additional layer of silicon carbide that aims to lower the temperature in the lower layer, where the electronic components stick to degradable materials under the influence of heat.

Abstract: The paper deals with the tribological properties of investigated types of hard-faced materials at erosive wear process. Influence of inclination angle of elements on friction resistance and microhardness changes of hard-faced layer were investigated too. From quantitative aspect were hard-faced layers evaluated on the base of weight loses. From achieved results follow that inclination angle is one from determining factors on to material’s wear measure.

Abstract: The article describes the effect of the pressure in the chamber during the deposition of thin layers on the basic mechanical properties of thin layers based on carbon. Monitoring parameters are mainly nanohardness, coefficient of friction and adhesion between the layer and substrate. This parameters are observed using nanohardness tester and scratch tester. All observed layers had the same thickens of layers. Carbon layers generally have poor adhesion to the substrate. To improve the adhesion, is used the interlayer of titanium which is between the substrate and carbon layer. Carbon layers are mostly used for their very good sliding properties especially in cases where can not be used process fluids or where is necessary to reduce the friction between the two materials. The carbon layer can also be used in medicine (for their biocompatibility), for machine tools (for their hardness and abrasion resistance) or as barriers layers (for their high chemical resistance).

Abstract: This paper presents some experimental research followed by setting industrial criteria for evaluation of titanium screw dental implants coated with layers of carbon doped with silver and silicon. Coating was done by three laser deposition methods. The coatings were studied related to the laser deposition method, friction coefficient and adherence to titanium substrate. As well, a DEFORM 2D™ simulation of screw dental implant fixture is presented. Research was done in the framework of CarLa M-ERA.NET project. Only research done by Romanian partners is presented.

Abstract: In this study, Zinc oxide (ZnO) nanostructures have been fabricated on glass substrates coated with Titanium dioxide (TiO₂) of different layers, which act as seeded-template, by a solution-immersion method. The substrates were coated with TiO₂ by using sol-gel spin coating at five different layers of TiO₂: 1, 3, 5, 7 and 9. The effects of the layers to the growth of ZnO nanostructures were observed by using Ultraviolet-Visible (UV-Vis) spectroscopy, Raman spectroscopy and Photoluminescence (PL) spectroscopy. UV-vis spectra of films display the increasing of absorbance properties at visible region as the TiO₂ layers increase, as well as at UV region. Meanwhile, at visible region the transparency of TiO₂: ZnO films reduce as the layers of TiO₂ increase from 1 layer to 9 layers. Raman analysis shows the presence of ZnO in all the TiO₂ seeded-templates. From the result, it is confirmed the existence of mixed crystalline structure of both materials in these TiO₂: ZnO thin films and PL spectra of the films show seeded TiO₂ thin films has lower intensity of visible emission and high ratio of I_UV/I_VIS compared to the non-seeded TiO₂ This contributes to the lower structural defects, oxygen vacancies, impurities and has the most improved optical properties.

Abstract: Aluminium (Al) - doped zinc oxide (ZnO) nanorods was deposited using sol-gel immersion method. To study the effect of stannic oxide coating (SnO₂) on the structural properties of the ZnO nanorods, SnO₂ with different layers were deposited on the top of ZnO nanorods, from 1 to 5 layers. The structural properties of the samples have been characterized using field emission scanning electron microscopy (FESEM), atomic force microscopy and x-ray diffraction (XRD). The analyses showed that by increasing the deposited layer, the surface roughness of the samples reduced and also reduced the porosity of the surface.

Abstract: The aramid fabrics have been widely used in aerospace, military and protective clothes for light radiation stability properties. The reflection and transmission properties of two kinds of materials (Kevlar 49 fabric and Kevlar 49/Nomex blended fabric) and three weaves of aramid fabrics with different wavelength spectrum were evaluated by ultraviolet-visible-near infrared (UV–Vis–NIR) spectrophotometer analysis. The effects of fabric layers on the reflection and transmission performances of aramid fabric were also discussed. It indicated that the aramid fabrics have good thermal and light protective properties.

Abstract: This paper contains a layer characteristics analysis layer thickness, chemical analysis, surface quality-for the triple deposition with Ti, W and TiC on the ferritic-perlitic cast iron support, using electro-spark deposition method. The resulted surface quality by electro-spark deposition method is dependent by the quality and chemical composition of the electrode. The obtained layer was realized by multiple successive depositions, using different electrodes to combine the beneficial characteristics of the part surface with the appropriate succession.

Abstract: In this study, three kinds of single-layered spunbonded nonwovens with different specifications were prepared as materials. The relation between layer number and pore structure (morphology characteristics, pore size and pore distribution, and Solid Volume Fraction) was studied. The results show that mean pore size decreases as layer number increases and the degree tends to be gentle. But the change law of maximum pore size is not obvious. Furthermore, pore size distribution of single-layered or two-layered nonwovens is concentrated and further increase in layer number doesnt have obvious effects on it . Air permeability reduces when the layer number increases and the variation trend accords with that of mean pore size.