Advanced Materials Research Vols. 816-817

Abstract: Various problems of science and engineering that deal with dynamical systems can be described by partial difference equations. This article is concerned with a class of mixed partial difference equations with constant coefficients. We obtain necessary and sufficient conditions for all solutions of these equations to be oscillatory by finding the characteristic roots. An example is given to illustrate the results presented in this paper.

Abstract: A simple, convenient and accurate method for the kinetic study of photochemical oxidation of glucose by chloramine-T in acidic medium is described. The kinetic investigation shows the first order dependence of reaction rate on chloramine-T. With excess concentration of other reactants the reaction rate follows fractional order kinetics with respect to substrate. The reaction is catalyzed by H⁺ ions as well. A small salt effect and increase in reaction rate with increasing the intensity of light source is also observed. Addition of p-toluene sulphonamide retards the reaction rate. A suitable mechanism in agreement with observed kinetics has been proposed

Abstract: Concerning with an actual situation in the exploitation of technological waste, this contribution deals with the properties analysis of moulded parts made of thermoplastics containing added regrind. The aim of the experiments was to analyze mechanical properties of plastics with various percentage of added regrind into basic material. Material PBT (polybutylene terephthalate), mineral composite with 30% glass fiber, was used for experimental testing. The plastics specimens were made by injection moulding and tested by chosen mechanical properties. The yield of tested material had tendency to decline with added amount of regrind. Addition of regrind had no impact on change of tensile strength and hardness of tested materials with regrind. The values of Charpy impact test had decreasing tendency with increasing rate of regrind. The utilization of regrind at the production of new moulded parts is important from aspect of reduction plastics waste and pollution abatement of environment.

Abstract: The contribution examines the effects of the electrolyte chemical composition on the resulting AAO layer thickness, which is one of the main indicators of corrosion protection of aluminium parts and which also favourably affects mechanical properties of component surfaces. For comparison purposes, there were selected the electrolytes comprising sulphuric acid, oxalic acid, boric acid and sodium chloride. Anodizing time for all specimens was 210.00 minutes. At the same time, equal electrolyte temperature 22.00°C ± 13.64% as well as equal magnitude of the applied voltage 12.00 V ± 4.17% were determined for all specimens. The results obtained lead to the assumption that it is possible to replace conventional electrolytes by those that are more environmentally friendly, reduce the costs of their disposal and allow obtaining oxide layers of the same thickness. The admixture of sodium chloride plays here the crucial role and its effect on the thickness of the formed oxide layer has not been published yet in any study.

Abstract: In this article, parametric optimization for material removal rate (MRR) and surface roughness (SR) study on the powder mixed electrical discharge machining (PMEDM) of EN-8 steel has been carried out. Response surface methodology (RSM) has been used to plan and analyze the experiments. Average current, duty cycle, diameter of electrode and concentration of micro-nickel powder added into dielectric fluid of EDM were chosen as process parameters to study the PMEDM performance in terms of MRR and SR. Experiments have been performed on newly designed experimental setup developed in laboratory. Most important parameters affecting selected performance measures have been identified and effects of their variations have been observed.

Abstract: Surface Dielectric Barrier Discharges (SDBD) plasma treatment has been performed to produce uniform atmospheric plasmas in He and in open air in order to functionalize the polycarbonate surface. SDBD is used for different application, processing especially of low-cost polymeric materials, combining the advantages of non-equilibrium plasma properties with the ease of atmospheric-pressure operation. Contact angle measurements were used to record the short-and long - term variations in wettability of treated and untreated polycarbonate sheets. The modification process was determined with hydrophilic measurements evaluated by means of the SEE system drop test.

Abstract: The aim of this contribution is to present the properties of the hydrogenated DLC (a-C:H) films and to study their growth carried out in a special deposition technique based on Gaseous Thermionic Vacuum Arc (G-TVA) method. The mechanical properties were investigated on cross-sectional samples using the Fischerscope HM 2000 depth sensing indentation (DSI) tester.

Abstract: Polycrystalline CuIn(Se,S)2 (CISS) thin films with chalcopyrite structure were synthesized by sol-gel spin-coating method. Sequential reduction, selenization and sulfurization treatments were performed with hydrogen, Se and H2S vapor, respectively. The effects of different sulfurization times on the films were also studyed. X-ray diffraction (XRD), and SEM analysis have been employed to examine the structural properties and surface morphology of polycrystalline CISS thin films. The experimental results demonstrated that the obtained CISS had good crystallinity and uniformity.

Abstract: The drying of porous media is studied in this paper by means of the continuous approach and the control volume method. Both transport phenomena inside the porous medium and overall drying kinetics are analyzed. The model utilized in this study requires a lot of physical properties. All of them have been established experimentally. The capillary pressure, which depends on the moisture content, is obtained by a mercury intrusion curve.