Volume 3 Issue 2

Authors: Bülent Eker; Murat Alkan; Ay?egül Akdo?an Eker

Abstract: This study analyzed the use of environmentally friendly, cornstarch based bioplastic raw materials instead of polyethylene based raw material to produce flat drip irrigation pipes, which is the most efficient agricultural irrigation system. Two groups of raw materials were used in the study, low density polyethylene (LDPE) material and cornstarch based biodegradable- poly beta hydroxybutyrate (PHB) raw material. Mixtures are obtained by adding 4 types of PHB raw materials at the ratio of 25%, 30%, 35% and 40% and 5% black masterbatch separately in the form of granules. Test samples were prepared from these mixtures using extrusion film production method. Mechanical tests, shrinking tests and thermal analysis were performed on test samples. Of the raw materials with bioplastic mixture, only the sample obtained from 65% LDPE + 30% PHB + 5% black masterbatch was consistent with the values of commercially available flat drip irrigation pipes with 0.14 mm wall thickness, 443.54 % strain at break, 0.967 g/cm3 density and 123.36 °C melting point. Moreover, raw materials with bioplast additives obtained from the study are suitable for the use as an alternative material in the polyethylene applications used in the fields of agricultural and industry.

Keywords: Flat Drip Irrigation Pipe; Bioplastic; Polyethylene; Extrusion


Authors: Alla Vorobjova; Alena Prudnikava; Yuri Shaman; Boris Shulitski; Vladimir Labunov; Sergey Gavrilo; Alexey Belov; Alexander Basaev

Abstract: Aligned, highly uniform multiwall carbon nanotubes (MWCNT) in a porous anodic aluminum oxide (AAO) membrane were successfully grown by chemical vapor deposition (CVD). The effectiveness of MWCNT formation was studied with various synthesis parameters. It was found that high catalyst (ferrocene) concentrations led to formation of a thick layer of MWCNT arrays on top surface of AAO membranes, which led to decrease of the pores filling with nanotubes. It was shown that the growth mechanism of the nanotubes in the AAO pores by this method was not connected with the traditionally used transition metal catalysts, no matter whether they were in a deposited (localized catalyst) or volatile (injected catalyst) state. The pre-annealing process in air atmosphere inhibited the nanotubes formation in the AAO pores. We speculate that the formation of MWCNT s in the AAO pores is governed by the pore structure reconstruction (water desorption, phase transformation) during the high-temperature (870° C) CVD process, though this phenomenon needs further investigation.

Keywords: Chemical Vapour Deposition; Carbon Nanotubes; Porous Aluminum Oxide; Ferrocene; Xylene


Authors: Hitoshi Ozaki; Takahito Mima; Hiroshi Kawakami; Jippei Suzuki

Abstract: The new cutting process, Assist Gas Free laser cutting (AGF laser cutting), was developed and the cutting properties were investigated in our laboratory. In a previous study of AGF laser cutting by using circular polarized CO2 laser, basic properties have been investigated. On the other hand, when cutting of metallic materials with a linear polarized laser is performed, it is known that the cutting kerf might slant and critical cutting speed can be accelerated. These phenomena have been also observed in AGF laser cutting. However, more detailed research about the properties by using a linear polarized laser in AGF laser cutting is needed. In the present study, the effect of laser polarization on cutting properties in AGF laser cutting by using linear polarized laser was investigated. The cutting speed and direction were varied in order to study the influence of these parameters on the critical cutting speed and kerf shapes such as slant angle, width, and removed area of kerf. The study showed that when the cutting direction and the polarized direction were parallel, the kerf slant was depressed. In addition, the critical cutting speed could be the fastest in any other cutting direction.

Keywords: Assist Gas Free; Laser Cutting; Linear Polarization; Stainless Steel


Authors: E. Jajarmi; O. Fakhraei; S. Shahsavar Fard

Abstract: This paper presents a new method for optimizing the heat treatment of 4620 AISI steel in the steering wheel pinion. In the first place, the pinion was carburized and quenched in oil at 120 °C. The second step was stress-relief and temper by induction. Finally, a machining operation was carried out to make thread and spline. According to the standard, the surface hardness of spline should be 37-45 HRC. Meanwhile, the pinion should machine easily to prevent fast-failing of the machining tools. As a result, the mentioned procedure was repeated with different induction parameters. The most important induction parameters for this research were the power of induction and the coil motion speed. The diameter of the thick part of the pinion has a major role in the hardness of spline because of the thickness of the carburized layer after the machining process. Thus, this parameter was included in the experiments too. According to the results, it was found out that by increasing the induction power, the spline surface hardness decreased. In addition, the effect of high speed of coil motion was more than its lower one. This effect increases the hardness of spline surface intensely. Based on these findings, it was concluded that using low power induction, high coil speed and small diameter lead to lower costs, increased speed of the process and good machining ability. This study demonstrated that the proposed technique can be considered more suitable than the existing procedure.

Keywords: Induction; Pinion; Hardness


Authors: Yu. V. Zaika; E. K. Kostikova

Abstract: An efficient reduction of gaseous hydrogen isotope permeation through a metal wall is essential in several applications like hydrogen storage and distribution, hydrogen embrittlement protection, and tritium inventory in future fusion reactors like ITER. Hydrogen permeation barrier films often exhibit lower efficiency than anticipated. It is very difficult to identify and quantify the responsible mechanism since the defects can be of submicrometer dimensions and very sparsely populated. We considered hydrogen permeability through a cylindrical membrane (barrier) in the presence of protective coating defect at the inlet surface of a structural material. For various materials, when the processes of diffusion, desorption and dissolution are limiting, we present the mathematical models in the form of boundary value problems with non-linear and dynamic boundary conditions. On the basis of the implicit difference scheme, a computational algorithm of a boundary value problems solution is developed. Numerical simulation results of hydrogen permeation flux and diffusant distribution are presented. Qualitative regularities of steady state permeability regime establishment and delay times registered experimentally and depending on geometric characteristics of the membrane and physical parameters are identified.

Keywords: Hydrogen Permeability Models; Nonlinear Boundary-value Problems; Difference Schemes; Computer Simulation