Entity

Time filter

Source Type

Karaj, Iran

Heydari F.,Material and Energy Research Center | Maghsoudipour A.,Material and Energy Research Center | Hamnabard Z.,Ceramic Group | Farhangdoust S.,Material and Energy Research Center
Materials Science and Engineering A | Year: 2012

In the present work, barium calcium aluminosilicate glass matrix was reinforced by 10, 15, and 20. vol% nanoparticles of total stabilized zirconia (TSZ). X-ray diffraction and scanning electron microscopy were used to evaluate the microstructure features of the final composites. Mechanical properties of the heat-treated specimens at the SOFC application temperature (800 °C) were determined at ambient temperature for different times (1, 10, 30, 50. h). The obtained results show that mechanical properties were somehow improved in the presence of zirconia nanoparticles. © 2012 Elsevier B.V. Source


Khalkhali Z.,Iran University of Science and Technology | Hamnabard Z.,Ceramic Group | Eftekhari Yekta B.,Iran University of Science and Technology | Nasiri M.,Iran University of Science and Technology | Khatibi E.,Iran University of Science and Technology
Journal of Materials Engineering and Performance | Year: 2013

Mica-based glasses in the SiO2-Al2O 3-MgO-K2O-F system were prepared by a sintering method to investigate the effects of different amounts of hematite (Fe2O 3) on thermal and sintering behaviors besides machinability of the glasses by means of differential thermal analysis (DTA), X-ray diffraction, and scanning electron microscope techniques. DTA analysis on fine and coarse glass powders indicated that the main crystallization mechanism in this system occurred in the bulk rather than the surface. Increasing Fe2O 3 content to 5 wt.% improved machinability of the glass ceramic. Fe2O3 led to the disruption of the glass matrix and facilitated the nucleation of the crystalline phase. Precipitation of sellite (MgF2) crystals as heterogeneous nucleating sites for potassium phlogopite crystals acted as a second contribution to the machinability of the 5 wt.% Fe2O3-containing sample. However, introducing more than 5 wt.% Fe2O3 to the base glass prohibited the nucleation of MgF2, and as a result, large micas formed within the glass. This together with precipitation of cordierite aggregates in highly doped glass with Fe2O3 led to lower machinability in these samples. © 2012 ASM International. Source


Maghsoudipour A.,Material and Energy Research Center | Shabani M.O.,Material and Energy Research Center | Hamnabard Z.,Ceramic Group | Farhangdoust S.,Material and Energy Research Center
Journal of Ceramic Processing Research | Year: 2014

The objective of the present work is to study properties of a composite material consisting of zirconia nanoparticles in a glass matrix based on the system of BaO-CaO-SiO2-B2O3-Al2O3. Zirconia nanoparticles are added by 0-20 vol.% into the glass matrix to prepare the glass composites. Coefficient of thermal expansion, glass transition temperature and dilatometric softening point temperature of specimens are determined by means of dilatometry analysis. Coefficient of thermal expansion of base glass is 10.38 × 10-6 k-1 and by increasing zirconia content to 10, 15, and 20 vol.%, coefficient of thermal expansion reduces down to 9.88 × 10-6, 9.84 × 10-6 and 9.76 × 10-6 k-1 respectively. Sinterability of different specimens is studied by increasing zirconia nanoparticles. Electrical properties are measured in different temperatures, and results show that with increment of zirconia nanoparticles, temperature resistivity of specimens has been decreased. Microstructural investigation reveals a well-adhered bonding between the sealants and electrolyte. Source


Heydari F.,Material and Energy Research Center | Maghsoudipour A.,Material and Energy Research Center | Hamnabard Z.,Ceramic Group | Farhangdoust S.,Material and Energy Research Center
Journal of Materials Science and Technology | Year: 2013

To develop suitable sealants for intermediate temperature solid oxide fuel cells (IT-SOFC), glass-ceramics based on the CaO-BaO-B2O3-Al2O3-SiO2 system were studied. Coefficient of thermal expansion (CTE), glass transition temperature (Tg) and dilatometric softening point temperature (Td) of specimens were determined by means of dilatometer analysis and crystallization temperature was measured by differential thermal analysis (DTA). Also, crystallization behavior during prolonged heat-treatment and microstructure properties were studied by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Electrical properties were measured at different temperatures, and the results showed a high resistance (>104 Ω) at the SOFC operation temperature (600-800 °C). Moreover, mechanical properties of heat-treated specimens (1, 10, 30, 50 h) were measured. Microstructure investigation revealed a well-adhered bonding between the sealant glass-ceramic electrolyte and glass. © 2013. Source


Ghasemzadeh M.,Islamic Azad University at Tehran | Nemati A.,Sharif University of Technology | Golikand A.N.,Ceramic Group | Hamnabard Z.,Ceramic Group | Baghshahi S.,Imam Khomeini International University
Synthesis and Reactivity in Inorganic, Metal-Organic and Nano-Metal Chemistry | Year: 2011

Non-isothermal differential thermal analysis (DTA), X-ray diffraction (XRD), and scanning electron microscopy (SEM) were used to study the nucleation and crystallization behavior of mica glass-ceramics with LiF as nucleating agent. The models enabled establishing the kinetic parameters for crystal growth of individual phases. The activation energies for crystal growth were found to be in the range of 161-301 KJ/mol, 416-424 KJ/mol, and 583-1011 KJ/mol for base glasses, samples with substitution of Li 2O for K 2O and samples with addition of LiF, respectively. Formation of transparent glass-ceramics from studied glass-samples has been investigated. Transparency is assumed to occur in the samples with nanocrystalline structure. Copyright © Taylor & Francis Group, LLC. Source

Discover hidden collaborations