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    A novel method for production of foamy core@compact shell Ti6Al4V bone-like composite

    , Article Journal of Alloys and Compounds ; Volume 656 , 2016 , Pages 416-422 ; 09258388 (ISSN) Ahmadi, S ; Sadrnezhad, S. K ; Sharif University of Technology
    Elsevier Ltd 
    This paper presents a novel method for fabrication of bone-like Ti6Al4V foamy core@compact shell composite for utilization as substitutive implant for cortical bone having porous core. Seven prototypes with core-diameters of 0, 6, 8, 10, 12, 14 and 16 mm surrounded by dense shells of respective thicknesses 8, 5, 4, 3, 2, 1 and 0 were produced by an innovative two-stage packing/compaction sintering method. Density, porosity, Young's modulus and compression strength of the prototypes depended on the core diameter. Mechanical strength and Young's modulus of 10@16 (10 mm core, 16 mm diameter prototypes) resembled that of the human ulna bone. Creation of foam at the center was achieved by... 

    Effect of starting materials on the wear performance of NiTi-based composites

    , Article Wear ; Volume 334-335 , July , 2015 , Pages 35-43 ; 00431648 (ISSN) Farvizi, M ; Ebadzadeh, T ; Vaezi, M. R ; Yoon, E. Y ; Kim, Y. J ; Kang, J. Y ; Kim, H. S ; Simchi, A ; Sharif University of Technology
    Elsevier Ltd  2015
    NiTi alloys have exhibited significant potential as a matrix of wear resistant composites. In this study, in order to examine the effect of starting materials on the wear performance of NiTi-based composites, both elemental Ni/Ti and prealloyed NiTi powders were used to fabricate NiTi-6wt% nano-Al2O3 composites using hot isostatic pressing (HIP). Nanoindentation and microhardness test results indicate that the composite samples produced from the elemental Ni/Ti powders exhibited higher hardness and lower pseudoelasticity properties than those of the samples fabricated from the prealloyed NiTi powders; this is attributed to the higher amount of... 

    Microwave-assisted sintering of Al2O3-MWCNT nanocomposites

    , Article Ceramics International ; Volume 43, Issue 8 , 2017 , Pages 6105-6109 ; 02728842 (ISSN) Ghobadi, H ; Ebadzadeh, T ; Sadeghian, Z ; Barzega Bafrooei, H ; Nemati, A ; Sharif University of Technology
    Elsevier Ltd  2017
    Alumina-MWCNT composite was densified by microwave sintering. CNTs were coated with boehmite nanoparticles to enhance their distribution in composite samples. Calcination temperature of composite powder was determined by TGA analysis (5 °C/min). Samples containing 0 and 1vol%CNT were produced by cold isostatic pressing at 180 MPa. Microwave sintering (1520 °C for 45 min) was conducted under the flow of argon. Phase analysis of the calcined composite powder showed complete transformation of boehmite into gamma-alumina. The relative densities were 99.3% and 98.1% for monolithic alumina and composite, respectively. CNT addition improved the fracture toughness of alumina by ~37%. SEM images... 

    Synthesis and characterization of sol-gel derived hydroxyapatite-bioglass composite nanopowders for biomedical applications

    , Article Journal of Biomimetics, Biomaterials, and Tissue Engineering ; Volume 12, Issue 1 , 2012 , Pages 51-57 ; 16621018 (ISSN) Adibnia, S ; Nemati, A ; Fathi, M. H ; Baghshahi, S ; Sharif University of Technology
    The main purpose of this study is to prepare and characterize hydroxyapatite (HA)-10%wt bioglass (BG) composite nanopowders and its bioactivity. Composites of hydroxyapatite with synthesized bioglass are prepared at various temperatures. Suitable calcination temperature is chosen by evaluating of the phase composition. X-ray diffraction (XRD), Transmission electron microscopy (TEM) and Scanning electron microscopy (SEM) techniques are utilized to characterize the prepared nanopowders. The bioactivity of the prepared composite samples is evaluated in an in vitro study by immersion of samples in simulated body fluid (SBF) for predicted time. Fourier transformed infrared (FTIR) spectroscopy and... 

    Aging behavior of a 2024 Al alloy-SiCp composite

    , Article Materials and Design ; Volume 31, Issue 5 , May , 2010 , Pages 2368-2374 ; 02641275 (ISSN) Mousavi Abarghouie, S. M. R ; Seyed Reihani, S.M ; Sharif University of Technology
    In the present research work the 2024 aluminum alloy was reinforced with SiC particles via powder metallurgy method. The effect of heat treatment conditions on artificial aging kinetics was investigated. The solution treatment of the composite sample and the unreinforced alloy was carried out at 495 °C for 1, 2 and 3 h followed by aging at 191 °C for various aging times between 1 and 10 h. The existence of SiC particles led to increasing the peak hardness of the alloy. The peak hardness of the composite sample took place at shorter times than that of the unreinforced alloy for the samples solution treated for 2 and 3 h, but took place at longer times for the samples solution treated for 1 h.... 

    Investigation of the fracture resistance in hoop wound composites modified with two different reactive oligomers

    , Article Materials and Design ; Volume 30, Issue 8 , 2009 , Pages 3048-3055 ; 02641275 (ISSN) Abadyan, M ; Bagheri, R ; Haddadpour, H ; Motamedi, P ; Sharif University of Technology
    Rubber modification of hoop filament wound epoxy composites was investigated using amine-terminated butadiene acrylonitrile (ATBN) and carboxyl-terminated butadiene acrylonitrile (CTBN) oligomers. Both mechanical and physical properties of modified composites were investigated and the morphology of the samples was studied via scanning electron microscopy. Results indicated that, when added to the epoxy matrix, ATBN effected a superior increase in toughness, yet a more severe decline in compressive and flexural strength, compared to CTBN. In contrast, in the case of composite samples, incorporation of ATBN led to more favorable mechanical properties, from the viewpoint of both toughness and... 

    Use of rubber modification technique to improve fracture-resistance of hoop wound composites

    , Article Materials and Design ; Volume 30, Issue 6 , 2009 , Pages 1976-1984 ; 02641275 (ISSN) Abadyan, M ; Khademi, V ; Bagheri, R ; Haddadpour, H ; Kouchakzadeh, M. A ; Farsadi, M ; Sharif University of Technology
    Toughness improvement of an epoxy resin and respective hoop wound composite were investigated systematically using amine-terminated butadiene acrylonitrile (ATBN) liquid rubber. Rubber modification improves fracture toughness of epoxy resin with slight reduction in the glass transition temperature (Tg), flexural and compressive properties of resin. Impact resistance of composite is improved by rubber modification similar to modified resin. Interlaminar shear strength (ILSS), compressive modulus and strength, and flexural strength of composite decreased slightly with rubber modification. To interpret the data, the void content of composite samples was determined and the damaged surfaces of... 

    Mechanical strength improvement of mud motor’s elastomer by nano clay and prediction the working life via strain energy

    , Article International Journal of Engineering, Transactions B: Applications ; Volume 32, Issue 2 , 2019 , Pages 184-191 ; 1728144X (ISSN) Izadi, M ; Tabatabaee Ghomi, M ; Pircheraghi, G ; Sharif University of Technology
    Materials and Energy Research Center  2019
    In directional drilling, the most important thing that leads to pulling out the drill string is end of mud motor working life. Considering the working conditions of down hole mud motors; increasing the mechanical properties of their stator’s elastomer is crucial. Some attempts were done to increase the motor performance through geometrical changes but lack of material improvement is significant in previous studies. In this study, NBR/nanoclay composite samples were prepared through melt intercalation in an internal mixer and tested with regard to the temperature and drilling mud of down hole. Hardness, tear, fatigue and tensile test results of neat NBR elastomer and nanocomposite of NBR and... 

    CMC/celite superabsorbent composites: Effect of reaction variables on saline-absorbency under load

    , Article Iranian Polymer Journal (English Edition) ; Volume 19, Issue 8 , May , 2010 , Pages 571-579 ; 10261265 (ISSN) Pourjavadi, A ; Soleyman, R. A ; Ghasemzadeh, H ; Salimi, H ; Sharif University of Technology
    A series of superabsorbent composites were synthesized through graft copolymerization of acrylic acid (AA) onto carboxymethyl cellulose (CMC) in the presence of celite powder using N,N'-methylenebisacrylamide (MBA) as a cross-linking agent and ammonium persulphate (APS) as an initiator. The chemical structure and thermal properties of the composite hydrogels were characterized by FTIR spectroscopy and TGA methods, respectively. Morphology of the samples was examined by scanning electron microscopy (SEM). In free-state, the swelling conditions and hence the related data are not real, because in all their applications the swelling particles of superabsorbent must absorb aqueous solutions while...