نشریه علم و مهندسی سرامیک
پیاپی 3 (زمستان 1391)

In current paper، magnetite nanoparticles were prepared via co-precipitation method. Ammonia was used as precipitant agent and iron chlorides of (II) and (III) as iron sources. Dispersion of nanoparticles was investigated in both carrier fluids of water and kerosene and the effect of surfactant concentration was studied. X-ray powder diffraction، dynamic laser scattering، Fourier transform infrared spectrometry and alternative gradient force measurement were used for phase identification، size and distributions of nanoparticles adhesion of surfactant on nanoparticles and magnetic properties respectively. Results indicated that the mean particle size of nanoparticles are in the range of 18-44nm and 68-89nm for water and kerosene carriers respectively; which are depend on surfactant concentration. The magnetic properties such as the saturation magnetization are decreased when the concentrations of surfactants are increased

Anionic nano clay or Layered double hydroxides are a class of nano structure materials with unique physico-chemical properties similar to natural hydrotalcite minerals with chemical formula ofMg6Al2 (OH) 16. CO3. 4H2O. these compounds can be composited with many organic species such as biomolecules، DNA and vitamins to form nanobiohybrids. In this study، Ca–Al–NO3 layered double hydroxide (LDH) nanoparticles of varying sizes weresynthesised by a process involving co-precipitation under hydrothermal condition. This methodproduces stable homogeneous LDH suspensions under variable hydrothermal treatmentconditions with particle size in the range of 7. 5nm–2. 5 μm. Layered double hydroxides werecharacterized by X-ray diffraction، Fourier transform infrared spectroscopy، thermal gravimetric/differential thermal analysis، scanning electron microscopy and transmission electron microscopy (TEM) and nanosizer analyses. By increasing the hydrothermal treatment time، the crystallinityand the particle size of obtained LDH increased. Scanning electron microscopy and TEMobservations showed uniform hexagonal flake-like particles with high aspect ratio. Finally، Ca–Al–NO3 LDH did not show any acute cytotoxic effect up to 100 mg/mLas measured by 3- (4،5-dimethylthiazol-2-yl) -2،5-diphenyltetrazolium bromide assay

This research is intended to cover the creation of multilayer nanostructured titania coating on 304L stainless steel by sol-gel dip-coating method to study the effect of thickness and multilayer characteristic on the photocatalytic properties of this coating. A stable polimeric sol based on Titanium Tetraisopropoxide with diethanolamine as additive was used in the coating process and by repeated immersion process، coating samples with 1 to 5 layers were prepared using two methods، one stage heat treatment and multistage heat treatment. To investigate the properties of samples، following analysis methods are used; TG، DTA، XRD، SEM، AFM، surface roughness test and photocatalytic tests under UV and VIS irradiation. Analysis results of XRD، SEM and AFM showed nanometric scale of TiO2 particles in the coating samples. No evidence of discontinuity has been detected during cross section area examination of multi-layer coatings using SEM. The analysis results of DTA، TG and XRD showed the formation of crystalline anatase phase from the amorphous phase at temperatures around 350°C، then anatase to rutile phase transformation begins at 500°C، and finally completes at 700°C. The optimal temperature for heat treatment was determined as 450°C which is also confirmed by the results of photocatalytic tests. The effect of thickness and layer numerity on the photocatalystic propeties of cotings is one of the discovered results in this research. From the point of photocatalytic properties، the optimum thickness of titania coating was determined around 198nm، which belonged to 3-layers coating with three stage heat treatment. The average surface roughness (Ra) in multilayer coating samples with multistage heat treatment has been decreased from 0. 107 µm in one layer sample to 0. 0147 µm in five layer sample، when layer numbers increased

Ceramics are hard and brittle and typically exhibit higher compressive strength than metals. Because most of the ceramics reveal only elastic strains to failure، accurate measurement of these strains using the traditional SHPB technique is often not a trivial task. In this paper، the limitations of this technique for testing ceramics and the modifications necessary such as strain gaging the specimen، sandwiching the specimen between high-strength impedance matching inserts to avoid indentation into the bars and also using the “momentum-trap” assembly to avoid the reloading of the specimen are expressed. Other topics discussed in this paper include maximum strain rate that can be obtained in ceramics using an SHPB، the necessity of incident pulse shaping، using a tapered striker، specimen design considerations، and the effectiveness of the proposed modifications on the strain gage records by simulating in finite – element code ABAQUS/Explicit

The morphology and particle size cadmium selenide Nanocrystals can change by the volume ratio of the solvent mixture of ethanol amine and ethylene diamine in solution. XRD spectra of all samples showed a crystalline structure wurtzite. Crystallite size decreases with the increase of ethanol amine in mixed solution. FE-SEM images indicated nanoparticles and nanorod with different shapes and dimensions. With the increase of ethylene diamine ratio the size of structures is decreased. The mechanism of morphology formation is SCMT mechanism. Finally FTIR spectroscopy، forming crystals of cadmium selenide nanoparticles in each sample showed in 1380 cm-1 as CdSe peak.

In current paper، zinc oxide nanoparticles were prepared via hydrothermal method using zinc acetate as precursor. The effect of temperature on the morphology and particle size of particles was investigated. For this the samples were synthesized in temperatures of 100، 140، 150، 170 and 190 °C for 1 hr. The morphology and structure of nanoparticles were characterized using powder x-ray diffraction and scanning electron microscopy (SEM). The results showed that the reaction is completed at about 100°C. SEM investigations revealed that the morphology of nanoparticles is affected with temperature of hydrothermal process. The needle-like، spherical and hexagonal structures were identified in 100 to 190 °C temperature range. The mean crystallite size variation was 23-42nm.