Sharif Digital Repository

The aim of this study was to investigate the thermal behavior of Mg-doped calcium phosphate compounds. Nanocrystalline HA and β-TCP mixtures containing different magnesium contents were synthesized via an alkoxide sol gel method. The ratio of (Ca+Mg)P was kept constant at 1.67, and the Mg content ranged between 0 and 3 mol%. The influence of magnesium on the phase composition, chemical structure, thermal behavior and morphological characteristics of nanopowders was analyzed using X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), Simultaneous Thermogravimetry and Differential Thermal Analysis (STA/DTA), Scanning Electron Microscopy (SEM) and Transmission Electron... 

Aluminum powder and various volume fractions of SiC particles with an average diameter of 50 nm were milled by a high-energy planetary ball mill to produce nanocrystalline Al-SiC nanocomposite powders. Double pressing/sintering process was used to consolidate powders to cylindrical specimens. It was shown that a double cycle of cold pressing and sintering can be utilized to obtain high density Al-SiC nanocomposite parts without using a hot-working step. High resolution scanning electron microscopy (HRSEM), X-ray diffraction (XRD) and laser particle size analyzer (PSA) were used to study the morphological and microstructural evolution of nanocomposite powders and bulk samples. The role of... 

In this paper fabrication of a 0-3 ceramic/ceramic composite lead zirconate titanate, Pb(Zr0.52Ti0.48)O3 thin film has been presented and then a pressure sensor based on multilayer thin-film PZT diaphragm contain of Lead Zirconate Titanate nanocrystalline powders was designed, modeled and optimized. This multilayer diaphragm in general acts as sensor or actuator. ANSYS was used for simulation of diaphragm. Dynamics characteristics of this multilayer diaphragm have been investigated. By this simulation the effective parameters of the multilayer PZT diaphragm for improving the performance of a pressure sensor in different ranges of pressure are optimized. The optimized thickness ratio of PZT... 

Recently, co-powder injection molding process (2C-PIM) has attained considerable interest to fabricate complex-shaped functional materials. The aim of this work is to study the sintering compatibility between nanocrystalline yttria-stabilized zirconia (3Y-TZP) and PIM grade 430L stainless steel (SS) powders, which is the utmost important step in the 2C-PIM process. To evaluate the mismatch strain development during the co-sintering, the isothermal and nonisothermal behaviors of the ceramic and metal powders were studied. Small bilayers of 3Y-TZP/430L were made by a powder metallurgy technique and the feasibility of simultaneous sintering and joining of the composite layer was examined.... 

Various compositions of maleated ethylene-propylene-rubber (EPR-g-MA) toughened polyamide 6 without and with short glass fiber, i.e. 5-20 wt.% rubber and 5-20 wt.% fiber, are prepared using an industrial twin-screw extruder at different levels of feed rate (100-250 kg/h), screw speed (200-450 rpm) and barrel temperature (230-260 °C). Trial runs designed based on the Taguchi's orthogonal arrays are subjected to tensile, impact, scanning electron microscopy (SEM) and optical microscopy tests; and the results are used to perform the analysis of variance (ANOVA). It is shown that the rubber particle size decreases significantly by increasing the rubber content for the unreinforced blend. The... 

Tin sulfide (SnS2) has recently attracted considerable attention due to its layered structure that may form two dimensional morphologies. It is an n-type semiconductor with band gap and electron affinity similar to CdS and In2S3; therefore can be regarded as an alternative for these materials in thin film solar cells. Here, we synthesis of SnS2 nanoparticles with different morphology in different ratio of water-ethanol mixed solution by solvothermal method, and observe that more ethanol leads to large sheet like morphologies, while water based synthesis results in very small nanosheets. A challenge in wet deposition of device-quality thin films of SnS2 is the requirement for highly dispersed... 

In this study, the effects of TiO2 addition on the physical and photoelectrochemical properties of ZnO thin films have been investigated. The (TiO2)x-(ZnO)1-x nanocomposite thin films were dip-coated on both glass and indium tin oxide (ITO)-coated conducting glass substrates with various values of x, specifically 0, 0.05, 0.1, 0.25 and 0.5. Optical properties of the samples were studied by UV-vis spectrophotometry in the range of 300-1100 nm. The optical spectra of the nanocomposite thin films showed high transparency in the visible region. The optical bandgap energy of the (TiO2)x-(ZnO)1-x films increased slightly with increasing values of x. The crystalline structure of the nanocomposite...