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- 저자 : Omayma M (검색결과 4 건)
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Peter Nyanor,Omayma El‑Kady,Hossam M. Yehia,Atef S. Hamada,Koichi Nakamura,Mohsen A. Hassan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.5
Aluminum matrix composites reinforced with reduced graphene oxide (rGO) and hybrid of carbon nanotube (CNT) andrGO are fabricated by solution coating powder metallurgy process. The hardness, wear resistance and coefficient of thermalexpansion (CTE) of the reinforced aluminum composites and the associated microstructural changes with rGO range(0.2–0.6 wt%) and hybrids of 0.2 wt% CNT–rGO at different ratios have been investigated. The intensive microstructuralobservations show that rGO is adsorbed on Al particles and uniformly distributed in the Al matrix composites. The hardnessvalues of the composites increase significantly with rGO reinforcement exhibiting the maximum hardness at 0.4 wt% rGO.Compared with the hybrid composites CNT–rGO/Al counterparts fabricated by the same route and wt. percent of 0.2, thehardness values in the hybrid CNT–rGO increase considerably. Similar to the hardness, the results of wear tests also exhibitcorresponding variation in the values of the wear rates. The improvement in the wear resistance of the hybrid CNT–rGO /Alcomposite is pronounced in this work. Whereas the rGO reinforcements decrease significantly the wear rate of the aluminumbaseby 98%, the wear resistance of the corresponding hybrid CNT–rGO is significantly higher than that of the precedingcomposites. Maximum CTE reduction of 28% was recorded for hybrid CNT–rGO (1:1) reinforced composite.
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Peter Nyanor,Omayma El‑Kady,Hossam M. Yehia,Atef S. Hamada,Mohsen A. Hassan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.4
Aluminium (Al) matrix reinforced with carbon nanotubes (CNT), micron-sized titanium carbide (TiC) particles, and bimodal(nano + micron) hybrid TiC–CNT is fabricated by solution ball milling, followed by cold compaction and vacuum sinteringto improve the mechanical properties and reduce thermal expansion. The hardness, wear resistance, compressive strength andCTE of pure Al, 0.6 wt% CNT/Al, 10 wt% TiC/Al, and hybrid 10–0.6 wt% TiC–CNT/Al composites have been investigated inthis work. Analysis of strengthening mechanisms based on theoretical models, microstructure, and properties of constituentmaterials is performed. Microstructure analysis reveals an excellent distribution of the reinforcement phase and no new phaseformation in sintered composites. The hardness value of bimodal TiC–CNT reinforced Al composite is significantly higherthan monomodal TiC reinforced composite, reaching 2.3 times the hardness value of pure Al. Similarly, the wear resistanceimproved, and CTE reduced with CNT and TiC addition but is even significantly better in the hybrid reinforced composite. Experimental values of CTE show good agreement with the theoretical model. The strength and ductility of materials aremutually exclusive, but the compressive strength of pure Al has been doubled without significant loss in ductility throughthe use of bimodal-sized hybrid TiC–CNT reinforcement in this work.
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Ban M,Kassab,Hoda H,Hussein,Omayma M,Mahmoud,Gamal Abdel-Alrahman 대한해부학회 2019 Anatomy & Cell Biology Vol.52 No.2
Gestational diabetes mellitus is one of common medical complications of pregnancy. Hyperglycemia in utero impairs renal development and produces renal anomalies. Metformin has antioxidant properties and better glycemic control. Aim: assessment insulin and metformin effects on renal development of streptozotocin-induced gestational diabetic albino rats. Sixty virgin female albino rats were used. Once pregnancy confirmed, animals were randomly assigned into control, metformin, diabetic, diabetic plus insulin, diabetic plus metformin and diabetic plus insulin and metformin treated groups. Rats were sacrificed on the 20th day of gestation; fetuses were extracted and weighted. Fetal kidneys were extracted prepared for light, morphometric and electron microscopic examination. Diabetic followed by diabetic plus metformin treated groups revealed retardation of glomerular development in the cortical and Juxtaglomerular zones with a significant increase in the early immature glomerular stages and immature to mature glomerular ratio compared to other groups. Diabetic group also showed morphometric changes, shrunken and empty glomeruli, vacuolar degeneration and hemorrhage. Diabetic plus metformin group showed minimal improvement while diabetic plus insulin and diabetic plus insulin and metformin groups showed developmental, histopathological and morphometric improvement with best results in the combination group. Gestational diabetes mellitus (GDM) possess deleterious effects on fetal kidney development. Insulin improves the glycemic state and decreases GDM effects on fetal kidneys. Metformin produces mild protection while the combination of insulin and metformin produces the best glycemic control and protect fetal kidneys.
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Mostafa Eid,Saleh Kaytbay,Ahmed El‑Assal,Omayma Elkady 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.11
Poor interfacial structure and severe agglomerations of carbon fiber (CF) are significant problems that face carbon fiberreinforced aluminium (CF/Al) composites. Thus, CF was surface modified with nano copper particles (Cu) to overcomethese problems. Two groups of CF/Al composites (uncoated and coated) at different weight percentages of reinforcement(0, 5, 10, 15, and 20) were fabricated using the planetary ball milling method and then uniaxially hot coined at 550 ℃ under700 MPa. The results showed that CF refined the crystallite size of the Al matrix, and no Al4C3 or Al2Cu were detected inXRD patterns. The density and thermal expansion of composites reduced with increasing CF percentage in all samples. The electrical and thermal conductivities are improved up to 10 wt% of uncoated reinforcement and 15 wt% of coated one. The mechanical test results revealed that by increasing CF, the compressive strength of composites decreased while thewear properties improved for both groups. Cu deposition on CF improved the bonding between reinforcement and matrix,producing composites with better interfacial bonding, fewer agglomerations and porosity, and higher values of the propertiesof the composites.
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