Browsing by Author "Daoush, Walid M"

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    Fabrication and characterization of Copper/Silicon Nitride composites
    (TECHNO-PRESS, 2016-09) El-Nikhaily, Ahmed E.; Daoush, Walid M; Ahmed, Mahmoud A
    Copper/silicon nitride (Cu/Si3N4) composites are fabricated by powder technology process. Copper is used as metal matrix and very fine Si3N4 particles (less than 1 micron) as reinforcement material. The investigated powder were used to prepare homogenous (Cu/Si3N4) composite mixtures with different Si3N4 weight percentage (2, 4, 6, 8 and10). The produced mixtures were cold pressed and sintered at different temperatures (850, 950, 1000, 1050 degrees C). The microstructure and the chemical composition of the produced Cu/Si3N4 composites were investigated by (SEM) and XRD. It was observed that the Si3N4 particles were homogeneously distributed in the Cu matrix. The density, electrical conductivity and coefficient of thermal expansion of the produced Cu/Si3N4 composites were measured. The relative green density, sintered density, electrical conductivity as well as coefficient of thermal expansion were decreased by increasing the reinforcement phase (Si3N4) content in the copper matrix. It is also founded that the sintered density and electrical conductivity of the Cu/Si3N4 composites were increased by increase the sintering temperature.
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    Investigation of the effect of SiC content on the microstructure, physical properties and hardness of SiC/Ni composites
    (NATL ACAD SCIENCES UKRAINE, 2019) Daoush, Walid M; Qassem, Ibrahim S; Ali, Ahmed, I; Chowdhury, Mahmudun N; Makled, Hanan M.
    Nickel matrix composites reinforced with alpha-silicon carbide of various concentrations (up to 4 wt.%) were investigated. Samples were made by powder mixing followed by a process of powder technology. The resulting SiC/nickel composite powders were cold compacted at 400 MPa in a single-axis head, followed by sintering in a controlled furnace at 1000 degrees C in an atmosphere of sintering a hydrogen/nitrogen mixture of 3:2. The SiC/Ni powders, as well as crushed and polished consolidated composites were investigated using a scanning electron microscope and X-ray diffraction (XRD). The microstructures of the obtained sintered SiC/Ni composites show a uniform distribution of SiC particles in the nickel matrix. XRD data showed that the sintered SiC/Ni composites consist mainly of (fcc) Ni as the main phase and alpha-SiC phase. To assess the sintering process of the obtained SiC/Ni composites, their density, electrical conductivity, coefficient of thermal expansion at various temperatures, and hardness were measured. The relative density, electrical conductivity, and thermal expansion coefficient of the sintered SiC/Ni composites obtained decreased; hardness increased by increasing the SiC content in the nickel matrix.