Browsing by Author "Elkady, Omayma A."

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Effect of consolidation techniques on the properties of Al matrix composite reinforced with nano Ni-coated SiC
(ELSEVIER SCIENCE BV, 2018) Abolkassem, Shimaa A.; Elkady, Omayma A.; Elsayed, Ayman H.; Hussein, Walaa A.; Yehya, Hosam M.
Al/Ni-SiC composite was prepared via powder metallurgy technique. SiC particles were coated with 10 wt% nano nickel by electroless deposition, then mixed by three percents (5, 10 and 15 wt%) with Al powder in a ball mill using 10: 1 ball to powder ratio for 5 h. Three types of sintering techniques were used to prepare the composite. Uniaxial cold compacted samples were sintered in a vacuum furnace at 600 degrees C for 1 h. The second group was the vacuum sintered samples which were post-processed by hot isostatic press (HIP) at 600 degrees C for 1hr under the pressure of 190 MPa. The third group was the hot pressed samples that were consolidated at 550 degrees C under the uniaxial pressure of 840 MPa. The results showed that the hot pressed samples have the highest densification values (97-100%), followed by the HIP samples (94-98%), then come the vacuum sintered ones (92-96%). X-ray diffraction analysis (XRD) indicated the presence of Al and Al3Ni, which means that all SiC particles were encapsulated with nickel as short peaks for SiC were observed. Hardness results revealed that HIP samples have the highest hardness values. The magnetization properties were improved by increasing SiC/Ni percent, and HIP samples showed the highest magnetization parameter values. (C) 2018 The Authors. Published by Elsevier B.V.
Electrochemical Surface Modification of Aluminum Sheets Prepared by Powder Metallurgy and Casting Techniques for Printed Circuit Applications
(SPRINGER INDIA, 2019) Yehia, Hossam M.; Elkady, Omayma A.; Reda, Y.; Ashraf, K.E
Two series of Al sheets are coated with different thicknesses of copper-deposited film from 10 to 40 mu m by the electroplating technique. The first group is the fresh cast Al sheets, and the other is the recycled water-atomized Al powder prepared by the technique of powder metallurgy. Microstructure and phase structure were examined by XRD, optical microscopy and FESEM. Electrical conductivity, thermal conductivity and coefficient of thermal expansion (CTE) were investigated. The XRD showed that only Al and Cu peaks appeared for the cast Al sheet samples, but for the recycled ones other peaks corresponding to Al2O3 were also detected. The microstructure indicated that the coated Cu layer had a dendritic structure in a continuous pattern, but for the recycled samples the dendritic structure was not clear but continuous. Both the thermal and electrical conductivities were gradually increased along with the increase in the Cu thickness, while the CTE was decreased
Microstructure, physical properties and hardness of alumina short fibres/nickel matrix composites fabricated by powder technology
(SAGE PUBLICATIONS LTD, 2014) Daoush, Walid M.; Elkady, Omayma A.
Nickel matrix composites reinforced with different weight percent of alumina short fibres have been fabricated by powder technology route. The alumina short fibres were encapsulated by nickel layers using the electroless deposition technique. The produced alumina/nickel composite powders underwent cold compaction and sintering at 850?. The alumina/nickel powders as well as the consolidated composites were investigated by optical microscope, scanning electron microscope, XRD and VSM. It was observed that the surface of the alumina short fibres was completely coated with nickel layer and the microstructures of the consolidated compacts show homogeneous distribution of the alumina short fibres in the nickel matrix. The density, electrical conductivity, coercivity, retentivity, saturation magnetization and hardness of the produced alumina short fibres/nickel composites were measured. The relative sintered density and the saturation magnetization were decreased, but the retentivity, the coercivity and the hardness were increased by increasing the alumina short fibres weight percent in the nickel matrix.