International Journal of Materials
E-ISSN: 2313-0555
Volume 6, 2019
Notice: As of 2014 and for the forthcoming years, the publication frequency/periodicity of NAUN Journals is adapted to the 'continuously updated' model. What this means is that instead of being separated into issues, new papers will be added on a continuous basis, allowing a more regular flow and shorter publication times. The papers will appear in reverse order, therefore the most recent one will be on top.
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Volume 6, 2019
Title of the Paper: Experimental Researches by Applying Sonic Surface Treatments to Carbon Steels
Authors: Bolfa Traian
Pages: 39-43
Abstract: The paper presents some experimental results obtained by applying sonic surface treatments to carbon steels plastic deformed or cast. The goal of these tests is to obtain the increase of the performances of some materials that are at higher level used in industry. The method used was ion nitriding and thin layer deposition of TiN which have been developed on a large scale.
Title of the Paper: Mathematical Model of Dimethyl Ether Catalytic Transformation to Liquid Hydrocarbons Process
Authors: Valentin Doluda, Adel Latypova, Olga Lefedova
Pages: 34-38
Abstract: Catalytic transformation of dimethyl ether to liquid hydrocarbons is process of special interest for industry and scientific community. This process can be applied for liquid hydrocarbons production from biomass or waste organic products by consecutive biomass transformation to syngas, further methanol and dimethyl ether synthesis and dimethyl catalytic transformation to hydrocarbons. The process is characterized by high complexity therefor development of its model is of great interest as for increasing of target products yield as for reactor modelling and heat management. The article is devoted to the development of extended lumped kinetic model of dimethyl ether to hydrocarbons transformation based on Eley-Rideal catalytic mechanism derivation. A series of differential equations were developed and numerically solved using Levenberg Marquardt algorithm. Model includes carbon chain and carbon cycle forming. Developed kinetic model allowed to determined specific activation energies and exponentials factors for lumped reactions. The relative deviation of found specific activation energy and preexponential factors varies from 5 to 12% depends on calculations accuracy and components concentrations. Developed model characterize by not high consumption of computational time and its applicability for reactor modelling and heat management
Title of the Paper: Experimental Investigation of 3-D Surface Microtexture of Nickel-carbon Nanocomposite Thin Films
Authors: Ştefan Ţălu, Alicja Rąplewicz, Sebastian Stach
Pages: 27-33
Abstract: The study's aim was to identify the 3-D surface spatial parameters that describe the 3-D surface microtexture of the nickel–carbon (Ni–C) nanocomposite thin films composed of Ni nanoparticles with different average sizes embedded in amorphous hydrogenated carbon, prepared by the combining radio frequency magnetron sputtering technique and plasmaenhanced chemical vapor deposition (RF-PECVD). The deposition time was varied at 7, 10 and 13 min, respectively. The sample investigation was performed using an atomic force microscope, and the obtained data were analyzed and visualized using MountainsMap® Premium software to determine their stereometric surface engineering characteristics. The results from this study provide not only fundamental insights into the texture characteristics, but also directions toward their implementation in nano-tribological models
Title of the Paper: Controlled High-Temperature Sintering of Boron Carbide
Authors: Bogomil Popov, Nikolay Stoimenov, Dimitar Karastoyanov
Pages: 22-26
Abstract: The paper discusses the boron carbide properties. Two methods are used to examine and control the sintering process of boron carbide. For achieving sintering is used a Tammann furnace. First, it is used an electric furnace with the thermal couple for determining transmission coefficient of ZnSe infrared window, observed with an infrared thermal camera. Analysis of the temperatures with and without infrared glass are discussed. After setting the transmission coefficient to the camera, the material is sintered to desired temperatures and for the temperature control is used an infrared camera. The result of the controlled temperature is achieved boron carbide material, obtained in strict temperature environment.
Title of the Paper: Improvement on Characteristics of Transformer Oil using Nanofluids
Authors: S. Sumathi, R. Rajesh
Pages: 15-21
Abstract: Transformers plays an important role in the transmission and distribution systems. Even to this day, 75% of high voltage transformer failures are the outcome of improper dielectric insulation. The reliable operation and aging characteristics of the transformers mainly depend on the insulation material. Mineral oil has been used as insulation and coolant for almost a century in power transformers. Due to the development of extra high voltage in the recent scenario and to cope up with the increasing demand in the voltage level a nanofluids based transformer oil is proposed. In this work, nanoparticles such as Aluminium Oxide (Al2O3), Molybdenum disulfide (MoS2) and Titanium Dioxide (TiO2) are proposed with transformer oil to investigate the various critical characteristics like dielectric strength, acidity, interfacial tension, viscosity, flash point and fire point of the power transformer. The observed results show that the proposed nanofluids based transformer oil produces better performance than the normal transformer oil.
Title of the Paper: Reliability Analysis of Bending Strength of Porous Sintered Clay using Three-Parameter Weibull Probability Distribution
Authors: Muazu Abubakar, Mohd Nasir Tamin, Norhayati Ahmad
Pages: 8-14
Abstract: In this research, a three parameter Weibull probability distribution was used to model the reliability of the flexural strength of inexpensive porous sintered clay. The as-received clay and the porous sintered clay were characterized by XRF, XRD, BET and FESEM. The clay powders mixed with 10wt% cassava starch were compacted and sintered at a temperature of 1300°C. The flexural strength of the sintered samples (33 samples) was determined by three point bending test. The flexural strength data was analyzed using three-parameter Weibull with Minitab 15 software. Maximum likelihood (ML) and least square (LS) estimates were employed in determining the Weibull parameters. The Weibull modulus value of LS (3.28) was found to be higher than ML (2.21). the Weibull modulus obtained is found to be higher compared to other engineering materials while the threshold strength (11.18-12.97MPa) was lower than other engineering materials. The flexural strength analysis of porous sintered clay shows higher reliability and a three parameter Weibull gives detail reliability of the flexural strength of the porous sintered clay.
Title of the Paper: Durability of GCB Concrete Exposed to Sea Water Sulphates in the Region of Jijel – Algeria
Authors: A. Boumehraz M. A., B. Mellas M., C. Goudjil K., D. Boucetta F.
Pages: 1-7
Abstract: Significant deterioration has been observed on marine structures in the Jijel region, due to the low quality of the concrete produced and the aggressive nature of the external environment. The aim of this work is to study on concrete durability the grooved cubic blocks (GCB) immersed in the seawater near the North West pier of the port of DjenDjen under the effect of sulphates. On will retrieving cores from GCB immersed in sea water for 25 years at DjenDjen and the results obtained will compare with control specimens. Based on this study, it was concluded that the GCB concrete exhibited weak mechanical characteristics compared to the control specimens concrete, and a relatively slow penetration of the aggressive agents; as well as a significant reduction in compressive strength by 45 % of cores; and by 7 % for speed of sound at the age of 25 years. At the same age the carbonation depth test reached to 117.00 mm.
