Search published articles


Showing 21 results for Golozar

M.a. Golozar,
Volume 14, Issue 1 (1-1994)
Abstract


Kiani Rashid, A. Najafi- Zadeh, M.a. Golozar,
Volume 14, Issue 1 (1-1994)
Abstract


M.h. Fathi, V. Mortazavi, M.a. Golozar and K. Khosravi,
Volume 15, Issue 1 (7-1994)
Abstract

Tarnish and Corrosion behavior of three Commercial dental amalgams namely Am.1, Am.2, Am.3, have been investigated by utilizing in vitro tests. The corrosion and/or dissolution rate of the three dental amalgams were studied in 0.9 wt% NaCl Solution, artificial saliva and Ringer's solution. Potentiodynamic polarization technique was employed to study cathodic and anodic polarization behavior, from which the corrosion potentials and corrosion current densities were calculated. The corrosion potential and the corrosion current density of each amalgam was found to be affected by the nature of electrolyte used, as well as the Pre-immersion time. However, the order of corrosion potentials and corrosion current densities of the three dental amalgams examined, was found to be independent of the electrolyte used.
M. A. Golozar,
Volume 16, Issue 2 (1-1998)
Abstract

In this paper, the nucleation and growth of diamond/diamond-like coatings on austenitic (AISI 316) and ferritic (AISI 430) stainless steel substrates have been investigated using torch technique. The effects of substrate surface preparation has also been studied. The quality of coatings produced has been examined using optical and scanning electron microscopy, X-ray diffraction, Raman spectroscopy and atomic force microscopy. The results obtained revealed very good crystalline grains and coating on austenitic and clusters of semi-and non-crystalline particles on ferritic stainless steel substrates. It was also observed that mechanical polishing and/or chemical etching would increase the nucleation density. The nucleation density was a function of substrate temperature, as well.
A. Said and M.a. Golozar,
Volume 18, Issue 1 (4-1999)
Abstract

Combustion synthesis has been used to produce Fe-(Ti,W)C composites. A simple reactor was designed which made it possible to ignite the samples under controlled atmosphere. Samples with different W/Ti ratio were ingnited under argon atmosphere by an electric arc and a self-propagating reaction was initiated in each sample. Different composites such as WC in Fe-Ti matrix, WC+(Ti,W)C in Fe matrix, and (Ti, W)C in iron matrix were produced by changing W/Ti ratio in the starting materials. Examination of the microstructure revealed that WC had an angular morphology while (Ti, W)C particles were spherical.
M. A. Golozar and R. Bagheri,
Volume 19, Issue 1 (7-2000)
Abstract

In this paper , the effect of curing time and temperature as well as various primers on durability of high density polyethylene on plain carbon steel have been investigated. The aim is to increase adhesion, improve durability and also to produce a defect-free in order to improve the corrosion resistance of steel substrate. For this purpose, after surface preparation and applying a primer (zinc phosphate, polyvinylalcohol, resol, stearic acid, and polyurethane) polymer coating was applied using electrostatic powder coating system. Coatings having 300 µ thickness were produced and then subjected to primary and secondary curing treatments. In addition to adhesion, ductility, and corrosion tests, quality of coatings were studied using scanning electron microscopy. The results obtained revealed that, surface porosity and uniformity of metal/coating interface is a function of curing time and temperature, as well as of the primers used. The best results obtained after curing for 45 min at 230˚C. The effects of primers were as following: no primers
A.r. Kiani Rashid and M. A. Golozar,
Volume 22, Issue 2 (1-2004)
Abstract


R. Mozaffarinia, F. Ashrafizadeh, M. A. Golozar,
Volume 22, Issue 2 (1-2004)
Abstract

The purpose of this work was to production of ceramic thin films by using of Sol-Gel process. For this purpose deposition of SiO2 on substrates of soda-lime glasses has been carried out. Coating treatments on prepared specimen were conducted in a Sol solution by means of dipping at various times. After drying and performing appropriate heat treatment on each sample, the thickness of coated layer was measured by means of roughness method. Some of the specimens were also exposed to heat and chemical environment to evaluate the coating resistance in such media. SEM examination and EDAX and XRD analysis of coating layers was also conducted on some samples. The results indicated that by Sol-Gel method, it is easily possible to achieve thin layers in the scale of one hundredth micron meter. Any change of the thickness layer on the surface is negligible and the quality of the coating is excellent. Also, experiments indicated that deposited coatings by Sol-Gel process, are stable and give enough durability in various environments.
M. F. Najafabadi and M. A. Golozar,
Volume 23, Issue 1 (7-2004)
Abstract

In this research work, the possibility of semi industrial production of Al-TiB2 and Al-ZrB2 composites, using reactive slag in a flame furnace have been investigated. For this purpose, commercial pure aluminum and powder mixture of TiO2 (ZrO2) , KBF4 and Na3AlF6 were used. The results showed that using a proper ratio of slag forming materials as well as proper amounts of the above-mentioned compounds make it possible to produce good quality Al-TiB2 and Al-ZrB2 compounds employing the conventional melting equipment such as a flame furnace.
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.
R. Bagheri and M.a. Golozar,
Volume 25, Issue 2 (1-2007)
Abstract

Using Electrostatic Spray Coating Technique, Polypropylene Powder (EPD 60R) was applied on carbon steel substrates at room temperature. In order to obtain a uniform coating, steel substrates with powder coatings were heated in a vacuum oven at various temperatures up to 250° C for various periods of time up to 45 min and a pressure of 200 mb. The coatings produced had thicknesses of around 470 microns. In order to modify the chemical structure of this polymer, the powder coatings containing various weight percentages of maleic (anhydride (MA) and a peroxide (TBHP or DCP) were also applied onto the steel substrates under the above conditions. Adhesion strength, wear resistance, and ductility of polymer coatings produced were assessed using ASTM standard methods. Results obtained revealed that the polymer coating containing 5 wt%. MA and 0.1 wt% TBHP had the best mechanical properties. Adhesive strength and wear resistance of this coating were 14.3 kgf and 250.3 cm, at 6 kgf, respectively, under the applied load of 6kg. Results obtained from DSC thermographs and IR Spectroscopy also proved the chemical bond formation (grafting) between the polymer and MA. The mechanical properties of coatings on steel substrate stem from such graftings.
H. Khabbazi, R. Bagheri, and M.a Golozar,
Volume 26, Issue 1 (7-2007)
Abstract

Polypropylene (PP) has poor adhesion to metals and other surfaces for its chemical structure. Hence, chemical modification of PP is necessary for metal surface coating application. In this research, grafting of maleic anhydride (MA) onto co(propylene-b-ethylene) in the presence of a dicumyl peroxide (DCP) was accomplished in a single screw extruder. Characteristics of the modified polymer were determined by Infra-red Spectroscopy (IR), Scanning Electron Microscopy (SEM), and adhesion test. Maximum grafting of MA was found to be 1.2832% for 1.5 pph of MA. Adhesion test showed that the samples containing 1 pph of MA (degree of grafting is 0.5816%) had better adhesion to steel surface (17.25 kgf).
S. Vahabzadeh, M. A. Golozar, F. Ashrafizadeh and A. Ghasemi,
Volume 27, Issue 2 (1-2009)
Abstract


M. Eshraghi Kakhki, A. Kermanpur, M. A. Golozar,
Volume 30, Issue 1 (Jun 2011)
Abstract

In this work, a 3D thermo-microstructural model was developed to simulate the continuous cooling of steel. The model was employed for simulation of cooling process of the gears made from a plain carbon steel (AISI 1045) and a low alloy steel (AISI 4140). Temperature-dependent heat transfer coefficients for two different quenching media were evaluated by experimental and computational methods. The effects of latent heat releases during phase transformations, temperature and phase fractions on the variation of thermo-physical properties were investigated. The present model was validated against cooling curve measurements, metallographic analysis, and hardness tests, and good agreement was found between the experimental and simulation results. This model was used to simulate the continuous cooling process and to predict the final distribution of microstructures and hardness in steel gears.
A. Fattah-Alhosseini, A. Saatchi, M.a. Golozar, K. Raeissi, B. Bavarian,
Volume 32, Issue 2 (Dec 2013)
Abstract

In this study, effect of potential on composition and depth profiles of passive films formed on 316L stainless steel in 0.05 M sulfuric acid has been examined using X-ray photoelectron spectroscopy (XPS). For passive film formation within the passive region, four potentials -0.2, 0.2, 0.5, and 0.8 VSCE were chosen and films were gown at each potential for 60 min. XPS analysis results showed that atomic concentration of Cr and Fe initially increase (E < 0.5 VSCE) and then decrease with potential. This decrease is due to surface dissolution of the Fe and Cr oxides. For both alloying elements, Ni and Mo, no obvious change in atomic concentration was showed. Results indicated that at higher potentials, before entering transpassive region, oxidation of Cr3+ to Cr6+ is happened.
M.r. Garsivaz Jazi, M.a. Golozar , K. Raeissi,
Volume 33, Issue 3 (Journal of Advanced Materials- winter 2015)
Abstract

In this study, the chemical composition, thickness and tribocorrosion behavior of oxide films prepared on Ti-6Al-4V alloy by anodising treatment in H2SO4/H3PO4 electrolyte at the potentials higher than the dielectric breakdown voltage were evaluated. The thickness measurement of the oxide layers showed a linear increase of thickness by increasing the anodizing voltage. The EDS analysis of oxide films demonstrated precipitation of sulfur and phosphor elements from electrolyte into the oxide layer. Tribocorrosion results indicated that the tribocorrosion behavior of samples was significantly improved by anodising process. Furthermore, the tribocorrosin performance of thesamples anodised at higher voltages was enhanced. SEM and EDS of worn surfaces indicated that the oxide layer on the samples anodised at lower voltages was totally removed, but for the samples anodised at higher voltages, the oxide layer was only locally removed within the wear track. Moreover, measurement of wear volume of the treated samples exhibited lower values on the samples anodised at higher voltages.
M. H. Tahmasebi, K. Raeissi, M. A. Golozar, A. Vicenzo, M. Bestetti,
Volume 35, Issue 3 (Journal of Advanced Materials-Fall 2016)
Abstract

In the present investigation, Mn-Ni binary nano-oxide was deposited by potentiodynamic method on stainless steel at room temperature and the effect of annealing process (at 200 oC for 6 h) on microstructure and electrochemical performance of the synthesized pseudocapacitor was studied. The results showed the significant effect of annealing process on increasing the capacitance and decreasing the charge transfer resistance of the electrode. Field Emission Scanning Electron Miscroscopy (FESEM) images depicted interconnected and random nano-flakes in the oxide film microstructure. Moreover, a partially crystallized structure consisting disorder hexagonal birnessite type phase was formed upon annealing in the deposited oxide film with about 10 %at Ni in composition. Based on the galvanostatic charge-discharge plots, the highest specific capacitance (384 F g-1) and specific energy (53 Wh kg-1) were found at specific current of 0.1 A g-1 for the annealed oxide electrode. Finally, cycle life test results at specific current of 10 A g-1 showed an excellent cyclability and an increase of about 23% in specific capacitance of synthesized pseudocapacitor after 5000 charge-discharge cycles in 1 M Na2SO4.


M. Farhadian, K. Raeissi, M. A. Golozar,
Volume 39, Issue 2 (Journal of Advanced Materials-Summer 2020)
Abstract

This work is focused on the effect of amorphous SiO2 addition on the phase transformation and microstructural evolution of ZrO2 particles. Considering the structural similarities between the amorphous ZrO2 and its tetragonal structure, XRD results showed initial nucleation of metastable tetragonal ZrO2 from its amorphous matrix upon heat treatment. This metastable phase is unstable in pure ZrO2 sample and transforms to a stable monoclinic phase at around 600 oC. However, addition of amorphous SiO2 to ZrO2 structure causes metastable tetragonal phase to remain stable up to around 1100 oC. The temperature range for stability of metastable tetragonal ZrO2 structure increased from about 150 oC in pure ZrO2 particles to around 500 oC in ZrO2-10 mol.% SiO2 composite powders. A further increase in SiO2 content up to 30 mol.% did not change the stabilization temperature range but the average particle size reduced around 1.6 times compared to pure ZrO2 particles. Stabilization of metastable tetragonal ZrO2 explained by constrained effect of SiO2 layer surrounding zirconia nuclei. The thickness of this SiO2 layer enhanced by increasing SiO2 content which limited the growth of ZrO2 nuclei resulting in finer particle sizes.


Page 1 from 2    
First
Previous
1
 

© 2024 CC BY-NC 4.0 | Journal of Advanced Materials in Engineering (Esteghlal)

Designed & Developed by : Yektaweb