International Journal of Materials

E-ISSN: 2313-0555
Volume 4, 2017

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 4, 2017

Title of the Paper: New Ways of Obtaining Super - Strengthened Large Components Based on Use of Optimal Hardenability Steel


Authors: N. I. Kobasko

Pages: 74-81

Abstract: In the paper new patented in Ukraine optimal hardenability steel and method of its designing is discussed to eliminate completely costly carburization process during thermal strengthening of large gears and improvement quality of hardening of big rotors, rollers by implementation intensive quenching processes. Usually, metallurgists are trying to improve me¬chanical properties of steel components by increasing alloy elements in steel that require slow cooling in oils or high concentration of water polymers solutions. It is proposed opposite way in increasing service life of machine components by cardi¬nal decrease alloy elements in steel and providing intensive cooling during hardening in water, water solutions combined with moving in quenching baths sprayers connected with the pumps. The proposed new approach is based on two fun¬damental phenomena which include creation of high surface compressive residual stresses after intensive quenching and obtaining super – strengthened material in surface layers after complete cooling. These two factors compensate decrease alloy elements in steel. The paper provides methodology of calculation for achieving maximal effect in residual surface compressive stress formation and super- strengthening of material depending on martensite finish temperature of steel. Effectiveness and bene¬fits are considerable due to saving alloy elements, energy and increasing service life of products. A team of Ukrainian lead¬ing specialists is organized to design appropriate software for governing and optimizing hardening processes with the aim of achieving above benefits and make environment clean. New steel and technology of hardening is based on UA Patents No. 109577 and No. 114174.

Title of the Paper: Monte Carlo Simulation of Terahertz Harmonic Generation in GaAs Quantum Wire Structure


Authors: Andrei V. Borzdov, Vladimir M. Borzdov, Vladimir A. Labunov

Pages: 70-73

Abstract: Electron transport in the GaAs/AlAs quantum wire transistor structure is simulated by means of ensemble Monte Carlo method under the effect of external alternating electric field. Nonlinear properties of electron transport are studied in terahertz range. The efficiency of high order harmonics generation in the structure is estimated for the lattice temperature of 300 K.

Title of the Paper: Software-Hardware Complex for Scanning and Analyzing of Drill Cores


Authors: Dolgiy K. A., Belashev B. Z.

Pages: 63-69

Abstract: A software-hardware complex for scanning and analyzing the lateral surface of drill cores was designed. A scan contains visual information on the lateral surface of a drill core, is easy to store and the risks of losing, mixing and destroying a drill core are minimum. The structure and design of the complex, scanning options and methods of control are described. Algorithms for constructing 3D scanning models, assessing mineral composition and other characteristics of a drill core and compressing a scan in the MATLAB computer mathematical system were developed. The complex was tested on drill cores from the Kostomuksha iron deposit. The accuracy characteristics of the algorithms were assessed on simulated images.

Title of the Paper: Nanoscale Patterns in Carbon–nickel Nanocomposite Thin Films Investigated by AFM and Stereometric Analysis


Authors: Ştefan Ţălu, Katarzyna Janus, Sebastian Stach

Pages: 54-62

Abstract: The objective of this study is a stereometric investigation of 3-D surface topography of the nickel–carbon (Ni–C) nanocomposite thin films composed of Ni nanoparticles with different average sizes embedded in amorphous hydrogenated carbon, prepared by RF-PECVD. The deposition time was varied at 7, 10 and 13 min, respectively, to study changes in the properties of the obtained films. The studied samples were taken with the help of atomic force microscopy (AFM) operating in a non-contact mode and examined in order to determine their stereometric surface engineering characteristics. This analysis of 3-D surface texture will give a deeper insight into their texture characteristics and their implementation in graphical models and computer simulation.

Title of the Paper: Percolation Theory Usage for Water Transfer Simulation While Drying out of Refractory Castables


Authors: Andrew V. Zabolotsky

Pages: 46-53

Abstract: A percolation structure model of refractory material was provided for mass transfer with temperature gradient (water evacuation while drying out) simulating. This allow providing pore structure model for material, which fits the experimental data. Coefficient of mass transfer for water, obtained with help of the suggested model was used for drying out process simulating for gunning mass, considering simultaneous chemical processes of hydration - dehydration. The results of simulation were not against data received by investigation of the gunning mass drying out at real metallurgical plant (damage character, observed at real installation can be explained using the suggested structure and mass transfer computer model).

Title of the Paper: Use of CdSe/Zns Core/shell Quantum Dots for Detection of Protoporphyrin IX and Polyaromatic Hydrocarbon Compounds


Authors: Jong Il Rhee

Pages: 40-45

Abstract: In this work, some CdSe/ZnS core/shell quantum dots (QDs) were synthesized and entrapped into a mixture of 3-glycidoxypropyltrimethoxysilane (GPTMS) and methyltrimethoxysilane (MTMS). The electron energy transfer from the QD-entrapped GA (mixture of APTMS and GPTMS) membrane to protoporphyrin IX (PpIX) or to polycyclic aromatic hydrocarbon compounds (PAHs) led to the quantification of PpIX in the linear detection range of 1-50 μM, of anthracene (ANT) and phenanthrene (PHE) in the linear detection range of 0.01-0.1 μM, and of pyrene (PYR) in the range of 0.005-0.05 μM.

Title of the Paper: Experimental Study on the Effects of Temperature and Concentration on the Thermal Conductivity of Graphene Nanoplatelets/DW Nanofluid


Authors: Masoud Vakili

Pages: 36-39

Abstract: In this paper, an experimental study on the effects of temperature and concentration on the thermal conductivity of Graphene Nanoplatelets/Deionized Water nanofluid is presented. The experiments were carried out for weight percentages of 0.00025, 0.0005, 0.001 and 0.005 in temperatures ranging from 25 °C to 50 °C. The results revealed that the thermal conductivity ratio enhances with increasing the solid volume fraction and temperature. Results also showed that, at higher temperatures, the variation of thermal conductivity ratio with solid weight percentages was more than that at lower temperatures. Moreover, the effect of temperature on the thermal conductivity ratio was more noticeable at higher solid volume fractions.

Title of the Paper: Weldability of Ti/Al Dissimilar Sheet Metal Joints Using Nd: YAG Pulsed Laser


Authors: K. Kalaiselvan, A. Elango, N. M. Nagarajan, K. Sekar

Pages: 31-35

Abstract: These The use of Nd: YAG Pulsed laser for the structure manufacturing sector has more advantages over the conventional welding due to its high productivity, non-contact treatment, automation, good finishing operations, less cost and better weldment quality. Titanium and aluminium alloys lead to many technical issues in laser welding. In particular, Ti6Al4V and AA2024 aluminium alloy thin sheets are investigated in this paper, being it is used extensively in the aerospace industries. Butt autogenous laser weldment tests were examined morphologically and micro-structurally. The mechanical features of the weld bead were evaluated. In addition to the speeds which are traditionally referred to, beam defocusing was considered. Softening in the fused zone is discussed via Rockwell hardness testing. Tensile test and fracture mode analysis were conducted on the specimens.

Title of the Paper: Influence of Cutting Parameters on Cutting Forces


Authors: M. Bourdim, A. Bourdim, S. Kerrouz

Pages: 26-30

Abstract: The turning is machining operation used in industrial manufacturing processes to obtain specific characteristics of machined work piece such as part geometry, surface roughness, etc. Cutting process create movements between the cutting tool and the work piece, which can affect the cutting forces between the tool and the work piece. The cutting forces depend on tool geometry and its material, work piece material, feed rate and cutting. These cutting forces could lead to reduced productivity, since lowered cutting speeds have a negative effect on the work piece surface. In this work we present an approach based on the study of cutting forces applied on the surface of work piece by Lathe tool is measured using experimental setup. The forces works on the work piece applies in three directions as longitudinal, axial and lateral directions.

Title of the Paper: Enhancing Conduction Heat Transfer in Phase Change Materials – Graphite Inserts


Authors: Bogdan Diaconu, Mihai Cruceru

Pages: 22-25

Abstract: The availability of the renewable energy sources and systems – solar especially – is generally not synchronous with the demand. Therefore, methods to ensure the supply during the periods with no availability had to be implemented. Such method is represented by Phase Change Materials (PCMs) which are used in thermal systems where primary energy sources are available with intermittence. PCMs effect is based on storage and release of a significant amount of heat with a relatively small temperature variation – due to the latent heat of fusion/solidification. PCMs widely used in thermal systems are organic compounds with low thermal conductivity which is a major drawback in implementation of thermal systems with high efficiency. The paper describes a method of increasing significantly the thermal conductivity of PCMs by means of graphite inserts.

Title of the Paper: Molecular Dynamics Simulation of Complex Formation by Lysine Dendrigraft of Second Generation and Semax Peptide


Authors: I. Neelov, E. Popova

Pages: 16-21

Abstract: Lysine dendrigrafts are new type of branched lysine peptides similar to lysine dendrimers but having central core consisting of eight lysine aminoacid residues. Therapeutic Semax peptide are regulatory peptides consisting of seven aminoacid residues and having antioxidant, antihypoxic and neuroprotective properties. It is known that lysine dendrimers could penetrate blood brain barrier, thus it can be assumed that lysine dendrigraft could penetrate it also and thus can be used in future for delivery of different drugs to brain. In present paper we investigated six different systems: first three systems contain 8, 16 and 24 Semax peptides and three other systems contain one lysine dendrigraft and 8, 16 and 24 Semax peptides correspondingly. All six systems were studied in water solvent wu\ith Cl counterions using molecular dynamics simulation method. For last three systems both complexes formation and equilibrium properties of complexes were investigated. It was shown that stable complexes consisting of dendrigraft and Semax peptides were formed in all three cases (with 8, 16 and 32 peptide molecules) and structures of these complexes were investigated. It was obtained that radius of gyration Rg of complex increase with number of peptides but shape anisotropy does not change much with size of complex.

Title of the Paper: Experimental Research on Flow Characteristics Close to Hydrophobic Surface


Authors: D. Jasikova, M. Kotek, S. Fialova, V. Kopecky

Pages: 10-15

Abstract: Combination of hydrodynamic and mechanical specification of the flow can reach the complex description of the liquid flow in the hydraulic system. The initial condition is the flexible wall and hydrophobic surface of the model. The simplification of the system leads to primary setup focused in one direction. It is the hydrophobic surface in our case. Here we present the study based on four various set of samples. We worked with hydrophobic surfaces, with contact angle (CA) above 90°, and with ultra – hydrophobic surfaces with CA above 120°. Increasing the contact angle leads from bubbles conglomeration to uniform air film. Using visualization methods and PIV we studied the air film layer on the hydrophobic surface and determined the velocity profiles in the water channel covered with hydrophobic surface. The existence of symmetrical air film close to hydrophobic surface has an effect on the character of the velocity profile and its boundary slip condition.

Title of the Paper: Synthesis of NaYF4 Compounds from Sulfide Precursors


Authors: Illariia A. Razumkova

Pages: 5-9

Abstract: The synthesis of compounds NaYF4 by "soft chemistry" of sulphide precursors (a simple Y2S3 and a complex NaYS2) is considered. Hydrofluoric acid solution (HF) having a concentration (5-45%) and a saturated aqueous solution of sodium fluoride with different content acidified by hydrofluoric acid (NaF+HF) is studied as the fluorinating component. When fluorination with hydrofluoric acid of different concentrations is decomposed, yttrium fluoride YF3 has been formed. The composition of NaYF4 compound is obtained as a mixture of cubic and hexagonal phases with dimensions of nanoparticles (α:30-100 nm, β:28-60 nm) with different synthesis conditions.

Title of the Paper: Comparison of Full Versus Fractional Factorial Experimental Design for the Prediction of Cutting Forces in Turning of a Titanium Alloy: A Case Study


Authors: John Kechagias, Konstantinos Kitsakis, Nikolaos Vaxevanidis

Pages: 1-4

Abstract: The present paper concerns with the analysis and the optimization of the main cutting force (Fc) during turning of Ti-6Al-4V ELI titanium alloy under dry cutting condition by applying either full or fractional experimental design. The main cutting variables (spindle speed, feed rate and depth of cut) were treated as inputs in whilst the main cutting force (Fc) was considered as the machinability output (quality (target). Therefore, a three parameter design was selected with each parameter having three levels. For the full factorial design, the complete combination array was selected consisted of 27 experiments. For the fractional factorial design only nine (9) experiments according to the L9 orthogonal array proposed by Taguchi’s DOE were used. The results obtained by both methodologies were further analyzed by applying ANOM and ANOVA techniques and compared in order to examine the suitability of the proposed experimental designs for machinability studies.