Showing 14 results for Morphology
A. Saatchi, H. Yan, and S. J. Harris,
Volume 20, Issue 1 (7-2001)
Abstract
Zinc was electrodeposited from an acidic sulphate solution on commercial steel sheet substrates galvanostatically at 10, 20, and 100 mA/cm2. The steel substrates had an average roughness number of 1.34 microns and a high percentage of its grains had their (111) planes parallel to the plate surface. During electrodeposition at 10 mA/cm2, on some specimens, there was an intense potential fluctuation around –870 mV vs Saturated Calomel Electrode (SCE). During this period zinc hydroxide precipitated on the surface. After a certain time, the potential dropped to –1020 for zinc deposition. Zinc nuclei were seen to precipitate from zinc hydroxide. Increasing current density changed nucleation mode from progressive to instantaneous, and also changed the size, morphology, and texture of zinc deposits.
Keywords: Zinc Electroplating, Current Density, Morphology, Orientation
K. Raeissi, A. Saatchi and M. A. Golozar,
Volume 23, Issue 2 (1-2005)
Abstract
On electropolished steel at low current densities, morphology and texture of electrodeposited zinc were investigated. Zinc coating is consisted of hexagonal crystallites laid on each other to produce packets. These packets are of different sizes and are stacked in different orientations to construct a homogeneous coating on steel substrate. This coating does not have texture, i.e., it has a random texture. With increasing current density, the morphology changes completely as each grain attains a special orientation. In this case, coating has a strong basal plane (0002) along with low angle planes (1013 and 1014). Coating obtained on mechanically polished surfaces consists of individual packets of zinc crystals, which are near each other with different
orientations. These coatings have a higher density of basal plane (0002) in comparison to electropolished surfaces. The morphology and texture variations with cathodic polarization and surface preparation of steel are due to their effect on nucleation and growth.
P. Delshad-Khatibi, F. Akhlaghi,
Volume 28, Issue 1 (6-2009)
Abstract
Solid Assisted Melt Disintegration (SAMD) is a relatively new method for producing metallic powder particles in which the kinetic energy transferred from a rotating impeller to the melt via a solid medium causes melt disintegration. These droplets are then solidified and separated from the media to obtain metallic powder particles. In the present study, sodium chloride (NaCl) was used to produce Al-6wt%Si powder particles. A specified amount of NaCl was introduced into the aluminum alloy melt and the slurry was stirred following a specified time-temperature regime to disintegrate the molten alloy into droplets. This blend was quenched in water to solidify Al powder particles and to dissolve NaCl in water. The Al powder particles were then collected, washed, dried, and subjected to laser particle size (LPS) analysis and scanning electron microscopy (SEM). The effects of different time-temperature regimes on the size and morphology of the resultant Al-6wt%Si powder particles were investigated and the optimum conditions for obtaining the finest spherical particles were established. It was concluded that the finest and most spherically shaped Al powder particles could be produced by stirring the slurry at 690 °C for 5 min followed by water quenching.
J. Jaafaripour Maybody, E. Salahi, A. Nemati, M.h. Amin,
Volume 30, Issue 1 (6-2011)
Abstract
In the present study, in-situ synthesis of carbon nanotube/hydroxyapatite nano composite powder with stable homogeneous dispersions of carbon nanotubes (CNTs) was carried out using surfactant as dispersing agent. By applying sol-gel method, dispersion in the hydroxyapatite matrix and its effects on the microstructure were investigated. The chemical and phase composition, structure and morphological and size analyses were performed using XRD, FT-IR, SEM, TEM/SAED/EDX, Raman, UV-Vis spectroscopy and differential scanning calorimetry (DSC). The influences of different dispersing agents (sodium dodecyl sulfate, SDS) as a benchmark for future dispersion experiments) and excitation wavelength are discussed and the results are compared to the commonly used UV-Visible spectroscopic analysis. The results indicated that synthesis of hydroxyapatite particles in the presence of the carbon nanotubes had the best homogenization of the carbon nanotube dispersion and faster crystallization of hydroxyapatite, and the use of SDS for dispersion carbon nanotubes at hydroxyapatite matrix rendered formation of hydroxyapatite coating on CNTs surface. The average crystallite size of heat-treated (at 600°C) samples, estimated by Scherrer,s equation, was found to be ~50-60 nm that was confirmed by TEM.
A. Elsagh,
Volume 31, Issue 2 (12-2012)
Abstract
In recent years, use of Sol-gel procedure for laboratory and industrial synthesis of Nanostructures and especially silica Nano-particles has increased. In this research, silica particles were synthesized by Sol-gel procedure and their physical properties were studied by means of Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Thermal Gravimetric Analysis (TGA). Effect of structural modifiers on the morphology and diameter of Nano-particles was investigated. In addition, the reaction was carried out in the presence of ultrasonic waves in periods of 10, 30 and 60 minutes and the effect of these waves on different stages of reaction was studied by means of SEM. Finally, in this research, spherical particles of 50 to 80 nanometer sizes were synthesized and characterized. They can be very useful hosts for lanthanide complexes that can be used in drug delivery systems, radiotherapy, photoluminescence applications and manufacturing of special lasers. Also, different amounts of Lanthanum Nitrate hexahydrate were added to the mixture during the creation of Nano-particles. Then, Simulated Body Fluid (SBF) was produced for the study of ability of the Nanostructures in regulated delivery of drugs such as Lanthanides, and releasing of Lanthanides in 10 minute periods for 80 h was studied. Lanthanide concentration in SBF was also studied by means of Inductively Coupled Plasma (ICP). According to the results of ICP, loaded Lanthanide was not released from the silica network. Loaded Lanthanides in the mesopores can be used in radiation, especially in cases of liver cancer.
M. Khalili Savadkoohi, A. Samadi,
Volume 31, Issue 2 (12-2012)
Abstract
Coherency elastic strain between γ and is one of the effective factors which affect the morphology, spatial re-arrangement and coarsening kinetics of precipitates in nickel-base superalloys. In this investigation, using X-ray diffraction (XRD) technique, the - constrained and unconstrained lattice misfits were calculated for different morphologies of the precipitates in Inconel 738LC nickel-base superalloy. The constrained and unconstrained misfits, hence the coherency elastic strains of different morphologies of the precipitates were calculated from the XRD patterns of the bulk sample and electrolytically extracted precipitates, respectively. According to the results, as the sizes of the particles increased the - coherency as well as the compressive strain of the precipitates was reduced and consequently their morphology changed from spherical to cubic, then flower-like, and finally dendritic shapes.
M. Ahmadi, Sh. Ebrahimi, M. Ahmadi,
Volume 33, Issue 2 (3-2015)
Abstract
This research aimed at producing microcellular foams (with cell size of 1-10 μm and cell density above 10 9 cell/cm3)
from PC/EPDM in order to use in medical devices. Due to the weak nucleation behavior of microcellular polycarbonate foams, it is difficult to prepare them. This research provides valuable information regarding the possibility of making microcellular foams from this polymer by using multiwalled carbon nanotubes (MWNT,s) as nucleating agents (the value of 1-3 phr). The nanocomposite samples were prepared in an internal mixer and foamed via a batch processing method using supercritical carbon dioxide as the foaming agent. The results showed that the addition of nanoparticles up to 3 phr improves the foamability of PC/EPDM blend. Furthermore, as nanoparticle content increased a decrease in cell size and hence an increase in cell density were observed. Another finding showed that cell size distribution is directly related to uniform dispersion of carbon nanotubes.
V. Rajaei, K. Raeissi, M. Shamanian, H. Rashtchi,
Volume 35, Issue 1 (6-2016)
Abstract
In this study, Ni-Mo nanocrystalline alloys were prepared on steel substrates by electrodeposition method from citrate-ammonia bath by applying current densities 30, 60 and 100 mA/cm2. Results indicated that the obtained coatings were uniform and compact. Moreover, molybdenum content in the alloy and current efficiency decreased with increasing electrodeposition current density. X-ray diffraction analyses indicated that all coatings were composed of face-centered cubic solid solution of molybdenum in nickel with grain size of 9-5 nanometer. Moreover, the most intensive plane in X-ray diffragtogram was (111). On the othe hand, roughness measurements indicated that surface roughness escalated with increasing current density. Corrosion behavior study showed decrease in corrosion current density of substrate with applying Ni-Mo alloy coatings. In addition, corrosion current density reduced with increasing molybdenum content of the coating and the minimum amount was related to the coating with 13 atomic percent molybdenum.
S. Shirinparvar, R.s. Razavi, F. Davar, M.r. Loghman-Estarki, S. Ghorbani,
Volume 35, Issue 4 (2-2017)
Abstract
In this research, the nanopowders of lanthanum and neodymium co-doped yttria were synthesized by sol-gel combustion method. Citric acid and glycine were used as the gel maker and fuel respectively. The effect of molar ratio of citric acid to glycine on the grain size and morphology was evaluated. The optimized products were characterized by X-ray diffraction (XRD), field-emission scanning electron microscope (FESEM), transmission electron microscope (TEM), UV–visible (UV–Vis), thermal gravimetric-differential thermal analysis (TG/DTA), and Fourier transform infrared spectrometer (FTIR). The optimized products which are synthesized with a molar ratio citric acid to glycine 1.06:1.06 have an average grain size of 30-40nm with spherical morphology, and without agglomeration. Also, their band gap is 3.29eV.
M. Alizadeh, A. Cheshmpish,
Volume 37, Issue 2 (9-2018)
Abstract
In this research, Ni-Mo-Al2O3 composite coatings were electro-deposited on the mild carbon steel in a citrate bath containing micro- sized Al2O3 particles. Afterward, the effect of the particle concentration in the electrolyte bath (ranging from 0 g/L to 30 g/L) on the microstructure, microhardness, and corrosion performance was evaluated. To investigate the microstructural changes and the surface morphology of the coatings, as well as the particle distribution in the deposits, optical and scanning electron microscopy coupled with the energy dispersive X-ray spectroscopy was utilized. The corrosion behavior of the prepared coatings was investigated in a 3.5 wt. % NaCl solution. The results showed that the presence of the Al2O3 particles in the Ni-Mo coatings changed the microstructure and also, increased the microhardness and corrosion resistance of them. It was also found that the desirable structure of the protruding crystallite morphology with no detectable pores could be achieved at the medium concentrations of reinforcement (e.g. 20 g/L). Further the optimum concentration of the particles in the electrolyte bath to attain the composite coating with the desirable microstructure and consequently, the desirable corrosion resistance was found to be 20 g/L.
M. T. Asadi Khanouki, R. Tavakoli , H. Aashuri,
Volume 38, Issue 2 (9-2019)
Abstract
In this research, the effect of temperature on the mean size of fracture surface features, as well as the relation between fracture surface morphologies and ductility of a La-based BMG as a relatively brittle alloy, was systematically investigated. After producing the alloy, three-point bending experiments, over a wide range of temperatures, were conducted on the samples; then the fracture surfaces were analyzed using scanning electron microscopy. The results demonstrated that the width of stable crack growth region (ΔW) was increased upon ductility (δp). Conversely, the mean size of the features on both stable (Ds) and fast (Df) crack growth regions and also, shear offset width (ΔL) were found to decrease with increasing ductility. In this case, the shear band instability was reduced, and the plastic strain could be more homogeneously distributed on the shear bands. The similarity of ΔL and Ds values suggested that the formation of vein pattern was caused by steak-slip behavior and multiple-step sliding inside the shear band through the fluid meniscus instability mechanism. Furthermore, the results obtained from correlation between ductility and fracture surface morphologies in the BMG indicated that the size of features was reduced with increasing ductility.
M. Zarchi, Sh. Ahangarani ,
Volume 39, Issue 1 (5-2020)
Abstract
The structural and optical properties of polycrystalline silicon films obtained on a silicon wafer by electron beam physical vapor deposition (EBPVD), were studied in this paper. These films were initially amorphous and changed to a crystalline solid phase during annealing. Annealing was performed in an inert gas atmosphere tube furnace at different temperatures. Micro-structure of the films was analyzed to know the relationship between the crystalline / amorphous composition, grain size and characteristics of the films. The results showed a decrease in roughness with increasing annealing temperature and structural density. Moreover, results of Micro-Raman spectrum showed formation and increase of silicon nanocrystals in the annealed condition when the thickness of the coating increased due to structural defects.
R. Bagheri, F. Karimzadeh, A. Kermanpur , M. Kharaziha,
Volume 40, Issue 2 (9-2021)
Abstract
A new method has been presented for the synthesis of copper (Cu)/copper oxide (CuO)-nanoparticles (NPs), based on the process of corrosion and oxidation of Cu-NPs on the surface of the gold electrode by nitric acid. Cu-NPs were deposited on the surface using potentiometric method. The high concentration of Cu-NPs was estimated by Differential Pulse Voltammetry (DPV). The process of growth and distribution of CuO-NPs on the surface of Cu-NPs using structural analysis of Fourier Transform Infrared Spectroscopy (FTIR) and X-ray diffraction (XRD) showed that nitrate was well absorbed and a sharp hydroxyl peak appeared and a phase of CuO NPs formed on the electrode surface. The surface morphology indicated that the average size reduced from about 150 nm to 50 nm in the presence of nitrate. This can be due to the oxidation of Cu nanoparticles on the surface and reduction of particle size compared to the absence of nitric acid. This simple and low-cost method can be used as a surface modification of antibacterial and active catalyst electrodes.
F. Rafati, N. Johari, F. Zohari,
Volume 40, Issue 4 (3-2022)
Abstract
In the present study, PCL/ZnO nanocomposite scaffolds containing 0, 5, and 15 wt.% of ZnO nanoparticles were prepared via the salt leaching/solvent casting method. The influence of ZnO nanoparticles on the morphology of prepared PCL/ZnO scaffolds was investigated using SEM images. The compressive strength test evaluated the effect of scaffolds’ morphology on mechanical properties. The XRD technique confirmed the desired phases in the scaffold composition. The results showed that the compressive strength and structural integrity of the scaffolds increased by increasing ZnO nanoparticles content as the reinforcement. However, the compressive strength and structural integrity decreased by increasing the amount of ZnO nanoparticles up to more than 5 wt.%. In summary, PCL/ZnO nanocomposite scaffold containing 5 wt.% of ZnO nanoparticles revealed the highest strength, compressive modulus, and structural integrity.
