Production of nano zinc borate (4ZnO·B2O3·H2O) and its effect on PVC

In this study, nano sized zinc borate powder with a formula of 4ZnO·B₂O₃·H₂O was synthesized using 2ZnO·3B₂O₃·3.0–3.5H₂O as a starting chemical which was produced using a wet chemical method. After dissolving 2ZnO·3B₂O₃·3.0–3.5H₂O in an ammonia solution, the clear solution was boiled until a white powder formed. The resultant powder was characterized with XRD, FTIR, TGA and TEM. XRD, FTIR and TGA results proved that the powder was belonged to the 4ZnO·B₂O₃·H₂O. Nano composites of 4ZnO·B₂O₃·H₂O–polyvinylchloride (PVC) were produced by injection moulding by adding 1 and 5 wt% zinc borate powders into PVC to enhance its flame retardancy. Limiting oxygen index (LOI) of virgin PVC increased from 41% to 47% and 54% for the 1 and 5 wt% zinc borate added PVC, respectively. Nano zinc borate addition into the PVC does not have considerable negative effect on the mechanical properties of zinc borate–PVC composites even at high amounts of 5 wt%.     

On the Effect of Carbon Nano-Tubes Addition on Structure and Superconducting Properties of Bi(Pb)-2223 Phase

In this work, a series of ceramic samples of Bi_1.6Pb_0.4Sr₂Ca₂Cu₃O _y (Bi(Pb)-2223) added with different amounts (0, 0.2 and 0.4 wt%) of carbon nano-tubes (CNT) are prepared from commercial powders and characterized. The study shows that the volume fraction of the Bi(Pb)-2223 phase decreases with CNT content while the grain size of the samples increases. The obtained cell parameters as well as the onset critical transition temperature are independent of this kind of addition. Also, it has been concluded that CNT addition makes the grains of the samples more connected. The measured magnetization in FC and ZFC modes indicates that CNT addition makes the grains of the samples more connected even if the irreversibility line is decreased. The variation of the residual resistivity and metalicity with CNT content suggests that the addition introduces disorder and defects into the samples. Also, the added samples present broad transitions to the superconducting state when compared to the pure one; this result may be associated to the increase of the volume fraction of the secondary phases. The activation energies, upper critical fields H _c2(0) and coherence lengths ξ(0) are extracted from the magneto-resistivity curves and their evolutions with CNT content are discussed.     

Effect of Eu doping on structural and magneto-electrical properties of La0.7Ca0.3MnO3 manganites

We have investigated the influence of europium (Eu) doping on structural and magneto-electrical properties of La_0.7Ca_0.3MnO₃ compounds. In order to analyze the physical mechanism of a spin disorder system and study their relative evolutions, two samples of nominal compositions (La_0.7?xEu_x)Ca_0.3MnO₃ (x = 0.0 and 0.1) have been elaborated and characterized. In addition to structural changes seen by this kind of doping, the magnetoresistance (MR) and resistivity are increased while the metal–insulator transition temperature is decreased. Comparing the experimental data with the theoretical models shows that in the metal-ferromagnetic region, the electrical behaviour of both samples is quite well described by a theory based on Kondo-like spin dependent scattering, electron–electron scattering, electron–phonon and electron–magnon scatterings. For the high temperature paramagnetic insulating regime, the adiabatic small polaron hopping model is found to fit well the experimental curves.     

KINETICS FOR FAST PYROLYSIS OF HAZEL NUT SHELL

Abstract

In this article, the potential utilization of hazel nut shell as a combustible residue was studied. To obtain liquid and gaseous products, the hazel nut shell was subjected to pyrolysis and it was converted to 49.3 % (w) gaseous and 20.0 % (w) liquid products at 475 °C for 7.5 minutes in a simple pyrolysis device The kinetic model used in the present study was based on fractional weight loss for each pyrolysis step. The simple fast pyrolysis was compared with TGA technique.     

Optimization of municipal solid waste (MSW) disposal in Saudi Arabia

Municipal solid waste (MSW) mainly comprises organics, paper, glass, plastics, metals, wood, etc. Rapid industrialization, high population growth rate, and fast urbanization have resulted in increased levels of pollution and MSW in Saudi Arabia. The amount of waste has been steadily increasing due to increasing human population and urbanization. Recovery refers to materials removed from the waste stream for the purpose of recycling and/or composting. There are various options available to convert solid waste to energy. Mainly, the following types of technologies are available: (1) sanitary landfill, (2) incineration, (3) pyrolysis, (4) gasification, and (5) anaerobic digestion. An integrated MSW disposal policy comprises (1) reduction of MSW source, (2) reuse of MSW, (3) recycling of MSW, (4) landfill and gas-to-energy conversion, and (5) MSW-to-energy conversion. Traditionally, MSWs have been disposed in landfills. Landfill is the most inexpensive waste disposal option. The main MSW disposal policies and barriers have been concluded in this study.     

Square cup deep drawing and 2D-draw bending analysis of Hadfield steel

Hadfield steel is the dominant material in the production of bullet proof steel helmet for military uses. The conventional bullet proof steel helmets are extensively fabricated by cold forming (deep drawing) 1.2 mm Hadfield steel sheets at room temperature. This paper presents the experimental analysis of the square cup deep drawing and 2D-draw bending of Hadfield steel as a continuation of an international bench mark research program organized by NUMISHEET'93 organising committee in Japan. The draw-in values of the flange have been determined for various punch travels in the square cup operation. The principal strains were evaluated in three directions from grid measurments for those punch travels. Springback values and sidewall curls were also described in 2D-draw bending operation. The experimental results were compared with that of ones in mild steel.