Showing 4 results for Aghaei
A. Moosavi, A. Aghaei,
Volume 5, Issue 2 (spring 2008 2008)
Abstract
Abstract: Auto-ignited gel combustion process has been used for producing a red hematite-zircon
based pigment. The combustible mixtures contained the metal nitrates and citric acid as oxidizers
and fuel, respectively. Sodium silicate (water glass) was used as silica source for producing zircon
phase. X-Ray Diffractometery, Electron Microscopy and Simultaneous Thermal Analysis were used
for characterization of reactions happened in the resulted dried gel during its heat-treatment.
L* a* b* color parameters were measured by the CIE (Commission International de I'Eclairage)
colorimetric method. This research has showed that solution combustion was unable to produce
coral pigment as the end product of combustion without the need for any further heat treatment
process.
A. Moosavi, M. A. Bahrevar, A. R. Aghaei,
Volume 13, Issue 1 (March 2016)
Abstract
An actuator is a device that converts input energy into mechanical energy. According to various types of input energy, various actuators have been advanced. Displacement in the electromagnetic, hydraulic and pneumatic actuators achieve by moving a piston via electromagnetic force or pressure, however the piezoelectric actuator (piezoceramic plates) displace directly. Therefore, accuracy and speed in the piezoelectric device are higher than other types of actuators. In the present work, the high-field electromechanical response of high-quality (1−x)(Bi 0.5Na0.5)TiO3–x(Bi0.5K0.5)TiO3 samples abbreviated to BNKTx with x = 0.18, 0.20, 0.22 and 0.24 ceramic materials across its MPB was investigated. The piezoelectrics and actuation characteristics were characterized. Ourresults indicate that x = 0.20, indeed, constitutes the best choice for the MPB composition in the system. Maximum of remanent polarization (37.5 μC cm−2) was obtained for x=0.20. High-field electromechanical responses were also obtained for BNKT0.20 samples. This material exhibited giant field induced strains of 0.13% under 1 kV mm -1 at room temperature.
Sara Ahmadi, Bijan Eftekhari Yekta, Hossein Sarpoolaky, Alireza Aghaei,
Volume 18, Issue 4 (December 2021)
Abstract
In the present work, monolithic gels were prepared through different drying procedures including
super critical, infrared wavelengths and traditional drying methods. Dense and transparent glasses
were obtained after controlled heat treatment of the dried porous xerogels in air atmosphere.
The chemical bonding as well as different properties of the prepared gels and the relevant glasses
were examined by means of Fourier transform infrared spectroscopy (FTIR), Brunauer-Emmitt-
Teller (BET) and UV-Vis spectrometer. Based on the obtained results, different drying conditions
affect the average pore size and the total pore volume of the studied gels. The mean pore size was
found to be 8.7 nm, 2.4 nm and 3.2 nm for super critical, IR radiation and slow drying in air
atmosphere, respectively. The glass network structure was significantly changed by heat treatment temperature so that the B-O-Si bonds were formed only after 450 °C. It was found that the gel dried under super critical condition was unable to reach to its full density all over the selected sintering temperature interval.
Zahra Shamohammadi Ghahsareh, Sara Banijamali, Alireza Aghaei,
Volume 20, Issue 2 (June 2023)
Abstract
Various analysis techniques were used to investigate the effects of P2O5 on the crystallization, mechanical features, and chemical resistance of canasite-based glass-ceramics. The results showed that canasite-type crystals were the primary crystalline phase in the examined glass-ceramics subjected to the two-step heat treatment, while fluorapatite was the secondary crystalline phase in some specimens. The microstructural observations by field emission electron microscope indicated that the randomly oriented interlocked blade-like canasite crystals decreased with an increase in the P2O5 content of the parent glasses. Among the examined glass-ceramics, the Base-P2 composition (containing 2 weight ratios of P2O5 in the glass) showed the most promising mechanical features (flexural strength of 176 MPa and fracture toughness of 2.9 MPa.m1/2) and chemical resistance (solubility of 2568 µg/cm2). This glass-ceramic could be further considered as a core material for dental restorations.
