Al Jīzah, Egypt
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Yousef S.,Akhbar Elyom Academy | Yousef S.,Messina University | Visco A.M.,Messina University | Galtieri G.,Messina University | Njuguna J.,Robert Gordon University
JOM | Year: 2015

The wear of polyoxymethylene (POM) is considered a key design parameter of polymer gears and some mechanical applications, and it determines the service time span. This work investigates the influence of carbon nanotubes (CNTs) on the specific wear rate of POM/CNT nanocomposites by using a pin-on-disk test rig (sliding only). The CNTs were synthesized with a fully automatic machine via the arc-discharge multi-electrode technique and subsequently dispersed in a POM matrix to manufacture test specimens. The CNT weight percentages were varied within the range 0–0.03 wt.% in three different operating media (air, distilled water, and mineral oil). The wear mechanism was examined by microscopy. The mechanical and thermal properties of POM/CNT were studied by using calorimetric analysis and by mechanical tensile testing. In addition, the thermal and mechanical properties were improved to an optimum CNT ratio of 0.02 wt.% due to the improvement in crystallinity of POM and a decrease in the fusion defects. The crystallinity degree increased by 7%, and the melting temperature also increased. The results further indicate that the specific wear rate (Ws) for POM/CNT containing 0.03 wt.% CNT in air and water media was improved by 73% and 66%, respectively, compared with virgin POM. In addition, the tensile strength of the mechanical properties and Young’s modulus increased by 31% and 29%, respectively. © 2015 The Minerals, Metals & Materials Society

Visco A.,Messina University | Yousef S.,Messina University | Yousef S.,Akhbar Elyom Academy | Galtieri G.,Messina University | And 3 more authors.
JOM | Year: 2016

Ultra-high molecular weight polyethylene (UHMWPE) is a very attractive polymer employed as a high performance material. For its high viscosity, dispersion of fillers is considered a critical point in UHMWPE nanocomposites preparation process. Currently, paraffin oil (PO) is used extensively to overcome this issue in an assisted melt-mixing process. In this work, we have prepared nanocomposites based on UHMWPE, carbon nanofiller (CNF) and PO mixed by different mixing methods: magnetic stirring, ball milling (BM), ultrasonic and Mini-Lab extruder (EX). The aim of this work was to check the effect of the dispersion method on the mechanical and thermal features of UHMWPE/CNF nano composites in order to obtain a material with improved mechanical and physical properties. The samples were characterized by calorimetric, density, mechanical tensile and rheological analyses. Experimental results highlighted that the nanocomposites produced by EX and BM exhibits the best dispersion, good filler matrix interaction and had significantly improved mechanical properties compared to pure UHMWPE. For instance, for the BM method, the yield strength improved to 18.6 MPa (+96%), the yield strain improved by 60%, while stress at break improved by 13%. In summary, the EX improved the stiffness while the BM produced better ductility, melting temperature and the crystalline degree of the nanocomposites. © 2016 The Minerals, Metals & Materials Society

Mohassieb S.A.,Akhbar Elyom Academy | Barseem I.M.,Akhbar Elyom Academy | Abdallah E.A.-F.,Electronics Research Institute of Egypt | El-Hennawy H.M.,Ain Shams University
Progress in Electromagnetics Research Symposium | Year: 2010

In this paper, miniaturized branch-line couplers (BLCs) are designed, simulated and fabricated using FR4 substrate at the operating frequency 2.4 GHz. First, high impedance open stubs (HIOS) are used to miniaturize the conventional BLC using the combinational-model (combinational of T and π-model). The proposed design is reduced by more than 57.5% compared to the conventional design. The second step is to use defected ground structure (DGS) underneath the BLC. The proposed design is capable to achieve any dividing ratio without reducing the width of the line, which means that the power handling capability is not reduced. In addition, suppression of higher order modes is achieved and more than 18% reduction in size as compared to the conventional shape is obtained. As a final step, the two techniques are combined together and a third BLC is proposed. Good agreement is found between experimental and simulated results using the software package Zeland IE3D.

Yousef S.,Akhbar Elyom Academy | Khattab A.,Cairo University | Osman T.A.,Cairo University | Zaki M.,Akhbar Elyom Academy
Proceedings of the 2012 1st International Conference on Innovative Engineering Systems, ICIES 2012 | Year: 2012

The production and industrial applications of carbon nanotubes (CNT) are recently the main concern of research in nanotechnology. CNT exhibit unique properties which have valuable commercial applications ranging from electronics to chemical processes. The main goal of the present paper is to develop the complete design of fully automatic system for producing carbon nanotubes (CNTs) by using deionized water and extra pure graphite multiple electrodes (99.9% pure). The advantage of the designed system is the increase yield of Carbon Nanotubes CNTs within the experimental limitations, through the increase of the number of cathodes and anodes and by using automatic feeding system for the electrodes, considering techniques at lower costs. The results of these experiments were examined by scanning electron microscope (HRSEM) and transmission electron microscope (HRTEM). The results show that the produced CNTs are multi-wall carbon nanotubes with average diameter of 25nm. © 2012 IEEE.

Yousef S.,Akhbar Elyom Academy | Yousef S.,Cairo University | Khattab A.,Cairo University | Zaki M.,Akhbar Elyom Academy | Osman T.A.,Cairo University
IEEE Transactions on Nanotechnology | Year: 2013

In last decade, polymeric gears have found wide applications in industrial fields. This is due to their advantages like noise reduction, self-lubricating features, weight reduction, cost savings as well as lower tribological characteristics in term of friction and wear. The main objective of this paper is to study the wear behavior of spur gears that makes polymer blended by carbon nanotubes (CNTs) (acetal). This was made by using appropriate adhesive oil (Paraffin) during injection moulding practice to produce thick flanges with diameter 134 mm and thickness 29 mm. The CNTs were produced by a fully automatic system using arc-discharge technique multielectrodes. The synthesizing CNT/acetal flanges contain 1% CNTs by weight. The flanges were machined using CNC milling machine to produce spur gears. The dispersion of CNTs in polymer were examined by scanning electron microscope. The experiments were performed at a running speed of 1420 r/min and at torques of 13 and 16 N·m. In addition, the mechanical properties of CNT/acetal have been tested. The results showed that the wear resistances of the CNTs/acetal spur gears increased with the addition of CNT. The strength, Young's modulus and stiffness also increased while the hardness was not affected by the addition of CNT. © 2002-2012 IEEE.

Yousef S.,Akhbar Elyom Academy | Khattab A.,Cairo University | Osman T.A.,Cairo University | Zaki M.,Akhbar Elyom Academy
Journal of Nanomaterials | Year: 2013

A new design of fully automatic system was built up to produce multiwalled carbon nanotube (MWCNT) using arc discharge technique in deionized water and extra pure graphite multiple electrodes (99.9% pure). The goal of the experimental research is to determine the yield of CNT in two different cases: (a) single plasma electrodes and (b) multiplasma electrodes, particularly 10 electrodes. The experiments were performed at constant parameters (75 A, 238 V). The obtained CNT was examined by scanning electron microscope (SEM), transmission electron microscope (HRTEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The results showed that the produced CNT is of type MWCNT, with a diameter of 5 nm, when using multiplasma electrodes and 13 nm when using single plasma electrodes. The yield of MWCNT was found to be 320% higher in case of comparing multielectrodes to that of single plasma electrodes. Under the experimental test conditions, a yield of 0.6 g/hr soot containing 40% by mass nanotube was obtained in case of single plasma electrodes and above 60% in case of multiplasma electrodes. © 2013 Samy Yousef et al.

Yousef S.,Akhbar Elyom Academy | Osman T.A.,Cairo University | Khattab M.,Cairo University | Bahr A.A.,Cairo University | Youssef A.M.,Cairo University
Advances in Tribology | Year: 2015

This work aims to study the wear characterization of common types of acetal polymer gears (spur, helical, bevel, and worm) using a new TS universal test rig, in order to obtain reliable results and as a reference when compared with acetal nanocomposite gears later. The TS universal test rig consists of three different units that are connected by a main driver shaft and a pair of constantly meshing metal spur gears, which transfer power to the bevel and worm test units. The first unit is used to test the bevel gears, the second unit is used to test the spur and helical gears, and the third unit is used to test the worm gears. The loading mechanism is similarly designed to block the brake mechanism. Hobbing and milling machines were used to machine an injection-moulded polymer flanges and produce the tested gears. All gear pairs, except the worm gear, have identical gear ratios. The experiments were performed at speed 1420 rpm and the torque was 4 Nm. The results showed that the wear rates (in the form of weight loss) of spur gears were consistent with the previous results and the other gear types had larger wear rates. © 2015 Samy Yousef et al.

Yousef S.,Akhbar Elyom Academy | Osman T.A.,Cairo University | Abdalla A.H.,Cairo University | Zohdy G.A.,Cairo University
JOM | Year: 2014

Although the applications of nanotechnologies are increasing, there remains a significant barrier between nanotechnology and machine element applications. This work aims to remove this barrier by blending carbon nanotubes (CNT) with common types of acetal polymer gears (spur, helical, bevel and worm). This was done by using adhesive oil (paraffin) during injection molding to synthesize a flange and short bars containing 0.02% CNT by weight. The flanges and short bars were machined using hobbing and milling machines to produce nanocomposite polymer gears. Some defects that surfaced in previous work, such as the appearance of bubbles and unmelted pellets during the injection process, were avoided to produce an excellent dispersion of CNT in the acetal. The wear resistances of the gears were measured by using a TS universal test rig using constant parameters for all of the gears that were fabricated. The tests were run at a speed of 1420 rpm and a torque of 4 Nm. The results showed that the wear resistances of the CNT/acetal gears were increased due to the addition of CNT, especially the helical, bevel and worm gears. © 2014 The Minerals, Metals & Materials Society

Elkaramany E.M.A.,Cairo University | Abo El-Hadeed F.G.,Cairo University | Ahmed A.S.S.,Akhbar Elyom Academy
Journal of Electromagnetic Waves and Applications | Year: 2014

Two-dimensional circuit is used to determine the resonant frequencies of the arbitrarily shaped, single-layer microstrip patch antennas. This circuit is based on the long transmission line model in the frequency domain. Derivation, analysis, and treatment of boundaries are given. Simple matrix form is obtained and the problem is reduced to an eigenvalue problem which is solved to get the required solution. The resonant frequencies of the resulting circuit are the required resonant frequencies of the patch antenna. Numerical results are given and are compared with the available analytical and experimental results reported by others. © 2014 Taylor & Francis.

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