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    Preparation of mullite-TiB2-CNTs hybrid composite through spark plasma sintering

    , Article Ceramics International ; Volume 45, Issue 13 , 2019 , Pages 16288-16296 ; 02728842 (ISSN) Orooji, Y ; Ghasali, E ; Moradi, M ; Derakhshandeh, M. R ; Alizadeh, M ; Shahedi Asl, M ; Ebadzadeh, T ; Sharif University of Technology
    Elsevier Ltd  2019
    A near fully dense mullite-TiB2-CNTs hybrid composite was prepared successfully trough spark plasma sintering. 1 wt%CNT and 10 wt%TiB2 were mixed with nano-sized mullite powders using a high energy mixer mill. Spark plasma sintering was carried out at 1350 °C under the primary and final pressure of 10 MPa and 30 MPa, respectively. XRD results showed mullite and TiB2 as dominant crystalline phases accompanied by tiny peaks of alumina. The microstructure of prepared composites demonstrated uniform distribution of TiB2 reinforcements in mullite matrix without any pores and porosities as a result of near fully densified spark plasma sintered composite. The fracture surface of composite revealed... 

    Polyacids for producing colloidally stable amorphous calcium carbonate clusters in water

    , Article Journal of Applied Polymer Science ; November , 2021 ; 00218995 (ISSN) Jia, X ; Basak Kayitmazer, A ; Ahmad, A ; Ramzan, N ; Li, Y ; Xu, Y ; Sun, S ; Sharif University of Technology
    John Wiley and Sons Inc  2021
    As an important precursor of crystalline phases, amorphous calcium carbonate (ACC), especially ultrasmall ACC clusters, have been attracting great interest in fundamental research, materials chemistry, as well as industrial applications. However, it is still challenging to synthesize stable ACC clusters in water that can be isolated and concentrated without severe aggregation. Herein, we report a facile dialysis method for producing colloidally stable ACC clusters that are well dispersed in water with the protection of specific polycarboxylic acids, which could be also easily deprotected by small-molecule acids like sodium citrate. Inherent proto-calcite short-range order is found to be... 

    Synthesis of nanocrystalline Ni/Ce-YSZ powder via a polymerization route

    , Article Materials Science- Poland ; Volume 31, Issue 3 , 2013 , Pages 343-349 ; 01371339 (ISSN) Abolghasemi, Z ; Tamizifar, M ; Arzani, K ; Nemati, A ; Khanfekr, A ; Bolandi, M ; Sharif University of Technology
    Oficyna Wydawnicza Politechniki Wroclawskiej  2013
    Pechini process was used for preparation of three kinds of nanocrystalline powders of yttria-stabilized zirconia (YSZ): doped with 1.5 mol% nickel oxide, doped with 15 mol% ceria, and doped with 1.5 mol% nickel oxide plus 15 mol% ceria. Zirconium chloride, yttrium nitrate, cerium nitrate, nickel nitrate, citric acid and ethylene glycol were polymerized at 80 °C to produce a gel. XRD, SEM and TEM analyses were used to investigate the crystalline phases and microstructures of obtained compounds. The results of XRD revealed the formation of nanocrystalline powder at 900 °C. Morphology of the powder calcined at 900 °C, examined with a scanning electron microscope, showed that the presence of... 

    Effects of nucleation agent particle size on properties, crystallisation and microstructure of glass-ceramics in TiO2-ZrO2-Li 2O-CaO- Al2O3-SiO2 system

    , Article Advances in Applied Ceramics ; Volume 109, Issue 6 , 2010 , Pages 318-323 ; 17436753 (ISSN) Nemati, A ; Goharian, P ; Shabanian, M ; Afshar, A ; Sharif University of Technology
    The objective of this study was to evaluate the effects of P 2O5 particle size distribution on the crystalline phases and microstructure of lithium disilicate glass-ceramics derived from the TiO2-ZrO2-Li2O-CaO-Al2O 3-SiO2 system for dentistry applications. The samples were made via fusion and casting procedure. Crystallisation as well as the morphology and microstructure of the samples were investigated using X-ray diffraction, differential scanning calorimetric and scanning electron microscopy. The results showed that the crystallisation of the samples occurred in the range of 500-650°C. The main crystalline phase was lithium disilicate (Li2Si2O5) along with Lithium metasilicate (Li2SiO3),... 

    Properties, crystallization mechanism and microstructure of lithium disilicate glass-ceramic

    , Article Journal of Non-Crystalline Solids ; Volume 356, Issue 4-5 , 2010 , Pages 208-214 ; 00223093 (ISSN) Goharian, P ; Nemati, A ; Shabanian, M ; Afshar, A ; Sharif University of Technology
    In this study, lithium disilicate glass-ceramic in the TiO2-ZrO2-Li2O-CaO-Al2O3-SiO2 system was investigated for dentistry applications by incorporation of P2O5 and Nb2O5 as nucleation agent. The influence of the particles size (nano and submicron size) and nucleating agents on the crystalline phases, microstructure, crystallization mechanism and mechanical properties were investigated. Our data indicated that in ceramic glass with nano and submicron P2O5, the main crystalline phase was lithium disilicate. The results also showed that change of P2O5 particle's size had significant effect on the crystalline phases and microstructure. By replacement of submicron P2O5 with submicron Nb2O5,... 

    Densification and properties of ZrO2 nanoparticles added magnesia–doloma refractories

    , Article Ceramics International ; Volume 42, Issue 14 , 2016 , Pages 15658-15663 ; 02728842 (ISSN) Ghasemi Kahrizsangi, S ; Barati Sedeh, M ; Gheisari Dehsheikh, H ; Shahraki, A ; Farooghi, M ; Sharif University of Technology
    Elsevier Ltd  2016
    In this work the effect of nano- and microZrO2 addition on the densification and hydration resistance of MgO–CaO refractories was investigated. 0, 2, 4, 6 and 8 wt% ZrO2 was added to MgO–CaO refractories that contain 35 wt% CaO. The crystalline phases and microstructure characteristics of specimens sintered at 1650 °C for 5 h in an electric furnace were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The physical properties are reported in terms of bulk density, apparent porosity and hydration resistance. Results show that with addition of ZrO2 the bulk density and hydration resistance of the samples increased while apparent porosity decreased. Also... 

    Densification and properties of Fe2O3 nanoparticles added CaO refractories

    , Article Ceramics International ; 2016 ; 02728842 (ISSN) Ghasemi Kahrizsangi, S ; Nemati, A ; Shahraki, A ; Farooghi, M ; Sharif University of Technology
    Elsevier Ltd 
    Up to 8wt. % of Nano-iron oxide was added to CaO refractory matrix. The crystalline phases and microstructure characteristics of specimens sintered at 1650°C for 5h in an electric furnace were studied by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The physical properties are reported in terms of bulk density, apparent porosity and hydration resistance. The mechanical behavior was studied by a cold crushing strength (CCS) and flexural strength at 1200°C test. As a result, it was found that the presence of Nano-iron oxide in the CaO refractory matrix induced 2CaO.Fe2O3 (C2F), CaO.Fe2O3 (CF) and 3CaO.Al2O3 (C3A) phase's formation, which improved the sintering... 

    On the Importance of Noncrystalline Phases in Semicrystalline Electrospun Nanofibers

    , Article ACS Applied Polymer Materials ; Volume 3, Issue 12 , 2021 , Pages 6315-6325 ; 26376105 (ISSN) Soleimani, F ; Mazaheri, M ; Pellerin, C ; Bagheri, R ; Sharif University of Technology
    American Chemical Society  2021
    Tailoring the properties of electrospun fibers requires a detailed understanding and control of their microstructure. We investigate the structure/property relationships in fabrics of randomly aligned fibers of polylactide, a prevalent biopolymer, either as-spun or after annealing and solvent-induced crystallization. In-depth characterization by field-emission scanning electron microscope (FESEM), wide-angle X-ray diffraction (WAXD), attenuated total reflection Fourier transform infrared (ATR-FTIR), and modulated temperature differential scanning calorimetry (MT-DSC) reveals that the as-spun fibers comprise crystalline and mesomorphic phases, as well as oriented but mobile amorphous chain... 

    The effects of SiO 2 and K 2O on glass forming ability and structure of CaOTiO 2P 2O 5 glass system

    , Article Ceramics International ; Volume 38, Issue 4 , 2012 , Pages 3281-3290 ; 02728842 (ISSN) Ahmadi Mooghari, H. R ; Nemati, A ; Eftekhari Yekta, B ; Hamnabard, Z ; Sharif University of Technology
    The effects of SiO 2 and K 2O were investigated on the glass forming ability (GFA) and structural characteristics of CaOTiO 2P 2O 5 system. Differential thermal analyzer (DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), FT-IR and 31P magic angle spinning NMR methods were applied for characterizations of the system. Unwanted crystallization in the initial three components base glass composition was observed by adding SiO 2 and crystalline phases such as TiP 2O 7, rutile (TiO 2) and cristobalite (SiO 2) were formed in it. The results showed that K 2O prevents crystallization of glasses and promotes the formation of glass. FT-IR and X-ray diffraction showed that the addition...