Mohammad Ali Golozar - Academia.edu (original) (raw)

Papers by Mohammad Ali Golozar

Journal of Power Sources, 2019

� Nanometric Ti/TiN multi-layer coating was deposited on 316L via PVD technique. � Hydrophobicity... more � Nanometric Ti/TiN multi-layer coating was deposited on 316L via PVD technique. � Hydrophobicity and corrosion resistance were increased by applying the coatings. � ICR of Ti/TiN multi-layer coated bipolar plates was lower than that of the bare one. � Corrosion resistance of 316L was improved by applying Ti/TiN multi-layer coating.

Transactions of the Indian Institute of Metals, 2017

In this research, Taguchi method (DOE technique) was used to optimize welding parameters in a dis... more In this research, Taguchi method (DOE technique) was used to optimize welding parameters in a dissimilar joint between the duplex stainless steel UNS32750 and the austenite stainless steel AISI 321 for the corrosion resistance. For joining, pulsed current gas arc welding with the ER2594 electrode was used. Pulse current, background current, % on time and current frequency were considered in three levels. Welding conditions were based on the L 9 Taguchi's orthogonal array design of experiment. Signalto-noise ratio was used to estimate the optimal conditions. The parameters and levels were considered as the optimal conditions in which the higher pitting potential could be obtained. Analysis of variance was carried out to determine the influential effect of each parameter. The pitting potential was evaluated by the potentiodynamic polarization test in the 3.5% NaCl solution at room temperature. Microstructural characterization and mechanical properties of the optimal joint were determined by optical microscopy and Vickers microhardness, respectively. According to the results of Taguchi method, the pulse current of 130 A, the Background current of 60 A, the % on time of 90% and the current frequency of 3 Hz were obtained as the optimal conditions. Pitting potential under optimal conditions (1.03 V) was close to Taguchi prediction (0.99 V). Analysis of Variance also indicated that the most effective parameter on the pitting corrosion was Background current. The percentage contributions of pulse current, background current, current frequency and % on time were 38.01, 32.48, 22.85 and 6.6%, respectively. The results showed that adjusting heat input led to the equal austenite-ferrite proportion.

Progress in Organic Coatings, 2008

... It is believed that the detached functional group is a carbonyl with a sulfonate branch, in a... more ... It is believed that the detached functional group is a carbonyl with a sulfonate branch, in agreement with results previously published by Dini [28]. Table 2. Elemental analysis results for C, H, N and S of coated steel Sample, C (wt%), H (wt%), N (wt%), S (wt%). ...

Journal of Applied Electrochemistry, 2008

ABSTRACT Nickel–Co nanocrystalline coatings were electrodeposited onto a carbon steel substrate w... more ABSTRACT Nickel–Co nanocrystalline coatings were electrodeposited onto a carbon steel substrate with and without saccharin addition. In the absence of saccharin, current density and adsorption of hydrogen complexes and/or intermediate components were distinguished as two effective parameters causing nanocrystalline electrodeposits. In the latter case, the growth active sites can be blocked easily at low current densities. By increasing the current density, a lower degree of adsorption was associated by a significant increase in surface diffusion of adions resulting in grain growth. Although, the nucleation rate is expected to increase with current density, it seems that the Ni–Co grain size is not reduced by the nucleation rate. Adsorption of saccharin molecules and/or decomposed sulfide species occurred in the saccharin contained bath, resulting in slow surface diffusion of adions. Therefore, finer grains were obtained which produced a smooth morphology instead of the pyramidal forms obtained in the absence of saccharin.

Journal of Applied Electrochemistry, 2004

The texture and morphology of zinc coatings electrodeposited on low carbon steel substrate have b... more The texture and morphology of zinc coatings electrodeposited on low carbon steel substrate have been studied. The predominant texture component of zinc coating at low overpotentials was pyramidal (11.5) and (11.6) non-fiber while at high overpotentials (00.2) fiber component dominated. The morphological analysis of the coating surface indicates that the non-fiber texture component results from epitaxial growth of zinc which develops through 2D nucleation and bunching growth of substrate surface microsteps, while the (00.2) fiber component starts from 3D nucleation and oriented growth to promote the plane having the lowest surface energy (i.e., (00.2)) parallel to the steel substrate surface. Zinc hydroxide adsorption prevents 3D nucleation at low overpotentials and this process favors epitaxial growth of the zinc deposit. At high overpotentials, inhibited zinc adsorption, in addition to increased number of active nucleation sites, promotes strong (00.2) fiber component. Such variation in texture indicates that the electrodeposit texture is strongly dependant on overpotential.

Journal of Manufacturing Processes, 2017

The aim of this study was to evaluate the effect of the bonding time on the transient liquid phas... more The aim of this study was to evaluate the effect of the bonding time on the transient liquid phase (TLP) bonding of SAF 2507 super duplex stainless steel to AISI 304 austenitic stainless steel. The bonding process was carried out at 1050 • C for different bonding times of 5, 10, 30 and 45 min to achieve a joint free of the inter-metallic compounds. For this purpose, an amorphous foil of Ni-7Cr-4.5Si-3.2B-3Fe alloy (AWS BNi-2) was used as the interlayer. Microstructure analyses were performed using optical microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy. Microhardness examinations and shear tests were performed to assess the effect of holding time on the mechanical behavior of dissimilar TLP bonded joints. The results indicated that the width of the athermally solidified zone was decreased with the increase of holding time at a constant temperature. The appearance of hardness peak values in the athermally solidified zone was due to the formation of eutectic compounds. Also, the shear strength was improved by increasing the bonding time. The TLP bonded joint fabricated at the bonding time of 45 min exhibited the best mechanical behavior due to the completion of isothermal solidification. Fractographic studies revealed that the fracture mode was completely ductile in the case of the joint made at the bonding time of 45 min.

Electrochimica Acta, 2016

Abstract The present study addresses the synthesis of manganese-nickel oxide thin films via poten... more Abstract The present study addresses the synthesis of manganese-nickel oxide thin films via potentiodynamic anodic electrodeposition as supercapacitor electrodes. We study in particular the effect of the deposition scan rate and of the Ni(II) to Mn(II) molar ratio in the deposition bath on the capacitive behaviour of mixed oxide electrodes. The increase of the nickel content in oxide thin films of composition Ni x Mn 1-x O y (with x in the range from 0 to 0.17) results in the increase of specific capacitance up to a maximum for about 10 at% Ni. The deposition scan rate affects the capacitive behaviour of mixed oxide electrodes through its effects on layer morphology and surface structure. In particular, thin film electrodes at about 10 at% Ni show a maximum in the specific capacitance for deposition scan rate of 600 mV s −1 , which is shown to be related to the attendant modifications in surface morphology and topography. After annealing at 200 °C, 6 h, partial crystallization of the amorphous structure of the as-grown mixed oxide takes place with formation of dispersed nanocrystalline domains. The annealed electrode at 10 at% Ni, with mass loading of 0.30 mg cm −2 , show the highest specific capacitance (250 F g −1 , at 0.1 A g −1 ), and specific energy and power as high as 34.5 Wh kg −1 (at 50 W kg −1 ), and 4.3 kW kg −1 (at 15.7 Wh kg −1 ). Mixed oxide of the same composition and mass loading reveal a 122% capacitance retention after 10,000 cycles in 1 M Na 2 SO 4 at 20 A g −1 .

international journal of iron and steel society of iran, 2013

A series of TiAlON coatings were synthesized in a gaseous mixture of argon, nitrogen and oxygen b... more A series of TiAlON coatings were synthesized in a gaseous mixture of argon, nitrogen and oxygen by cathodic arc evaporation method using a Ti-Al mosaic target. Oxidation of coatings was carried out by heating the coated samples at the temperatures of 500, 600, 700, and 800°C for 1 h in air atmosphere. It was found that heat treatment changed the microstructure and composition of the coating. The dark copper color of TiAlON films was also changed due to the heat treatment. The peak intensities of TiN were decreased and that of Fe was increased with an increase in heat treatment temperature. Furthermore, the amorphous Al 2 O 3 in grain boundaries was transformed to a crystalline structure with increasing temperature. The variation in the chemical composition of the coatings was recognized to be a function of heat treatment temperature. The oxidizing treatment promoted not only the growth of titanium and aluminum oxides on the pore wall of the coating, thereby allowing a partial pore s...

Journal of Failure Analysis and Prevention, 2019

In this study, the effect of porosity on hardness and strength of as-cast and aged nickel-aluminu... more In this study, the effect of porosity on hardness and strength of as-cast and aged nickel-aluminum bronze (alloy C95800) has been investigated. Optical and scanning electron microscopes were used to examine the microstructures and to characterize the fracture surfaces of the alloy, respectively. After aging, a grains in the microstructure were refined, distribution of eutectoid particle phases became more uniform and volume fraction of b' phase was increased. Hardness testing revealed that optimum aging was achieved at 350°C with more than 90% increase compared to the as-cast alloy. In order to eliminate the effect of pores on tensile data, and to evaluate aging process in terms of tensile strength, the concept of ''effective area'' was introduced as the total cross-sectional area minus the projected area of pores as obtained by fractography. Based on this concept, the effective strength of the cast alloy was calculated. The effective strength was also obtained by Ghosh's model; comparison of the results indicated good agreement of both methods. It was concluded that effective strength presented in this research could be an appropriate reference value when considering mechanical properties of porous casting alloys.

Materials Letters, 2012

In this research, nano iron oxide (Fe 2 O 3)/carbon black electrodes are prepared by mechanical p... more In this research, nano iron oxide (Fe 2 O 3)/carbon black electrodes are prepared by mechanical pressing method and evaluated as possible electrodes for electrochemical capacitors. Electrochemical properties of the produced electrodes are studied using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests in 2 M KCl electrolyte at different scan rates. Scanning electron microscopy (SEM) is also used to characterize the microstructure and nature of the produced electrodes. Electrochemical stability of the electrodes is investigated by switching the electrode back and forth for 500 cycles at 20 mV s À 1 .The results obtained show a specific capacitance of as high as 40.07 F g À 1 for 30:60:10 (carbon black:Fe 2 O 3 :polytetrafluoroethylene) electrode in 2 M KCl at 10 mV s À 1. The proposed electrode exhibits good cyclic stability and maintains 80% of the capacitance after 500 cycles. SEM images confirm the porous structure of Fe 2 O 3 /carbon black electrodes.

Journal of Thermal Spray Technology, 2013

ABSTRACT Because of the nature of the plasma spraying process, the physical and mechanical proper... more ABSTRACT Because of the nature of the plasma spraying process, the physical and mechanical properties of vacuum-plasma-sprayed structures of Ti-6Al-4V alloy are completely different from those of conventionally manufactured alloys such as bulk materials from casting and forging. To obtain desired mechanical and physical properties, vacancy and internal defects must be reduced, splat boundaries must be eliminated, and optimal phase compositions should be obtained through postdeposition heat treatments. To determine appropriate heat treatment processes, one needs to study the kinetic behavior of the as-sprayed microstructure at elevated temperatures. In the current study, the kinetics of the solid transformations found in Ti-6Al-4V alloys produced during the vacuum plasma spraying process was studied based on the Johnson-Mehl-Avrami theory. For the kinetic behavior of this alloy, the nonconstant temperature dependence of the transformation rate constant exhibits an irregularity at 900 °C, marking a change in the transformation mechanism. For the lower-temperature (<900 °C) curves, the constant gradient indicates a lack of change in the transformation mechanism, including homogeneous nucleation, with growth of α phase. For higher temperatures (>900 °C), a gradient change indicates a change in the transformation mechanism. The first mechanism was the formation of α-phase grain boundary, and the second mechanism was α-plate nucleation and growth from grain boundaries. The value of the transformation rate constant in the kinetics study of as-sprayed Ti-6Al-4V alloy was much higher than for material produced by the casting method. Using the results obtained from the kinetics of the $ \upbeta \to \upalpha + \upbeta $ phase transformation at different constant temperatures, a time–temperature–transformation (TTT) diagram for as-sprayed Ti-6Al-4V alloy was developed.

Journal of Materials Processing Technology, 2008

Hot-dip galvanized coatings have attracted increasing interest from the automobile industry and s... more Hot-dip galvanized coatings have attracted increasing interest from the automobile industry and steel producers because of their excellent corrosion resistance. Texture is an important factor, which affects the coating properties. Chemical composition of the zinc bath can strongly influence the texture of hot-dip galvanized coatings. In this study, lead content of the zinc bath was changed from 0.01 to 0.11wt.%. Specimens were prepared from zinc baths with different lead content and their texture was evaluated using X-ray diffraction. Corrosion behaviour of the specimen was analyzed by Tafel extrapolation and salt spray tests. Cross-sectional studies were performed using optical microscopy. Also, the spangle size of the specimens was determined using line intercept method. From the experimental results it was found that (00.2) basal plane texture component would be weakened by increasing the lead content of the zinc bath and coatings with strong (00.2) texture component have better corrosion resistance than the coatings with weak (00.2) texture component. In addition, the increase in lead content of the zinc bath would strengthen the (20.1), (10.3) and (10.0) texture components and stronger (20.1) high angle pyramidal plane texture component would decrease the corrosion resistance of the coating. Furthermore, spangle size and number of dull spangles would be increased by increasing the lead content of the zinc bath. Finally, it was found that increasing the lead content of zinc bath has no effect on the phases detected in corrosion products.

Journal of Applied Electrochemistry, 2007

ABSTRACT

Corrosion Science, 2012

ABSTRACT Effect of grain refinement and heat treatment on corrosion behavior of a friction stir p... more ABSTRACT Effect of grain refinement and heat treatment on corrosion behavior of a friction stir processed Mg-Y-RE alloy was studied. The ennoblement of pitting potential by ∼250 mV vs. SCE of processed samples as compared to parent alloy was attributed to grain refinement and uniform second phase distribution as a result of friction stir processing. Lower currents and positive open circuit potentials were observed in friction stir processed samples under free corroding conditions. Friction stir processing prior to peak hardening resulted in improved pitting potential when compared to the peak aged and processed samples. Electrochemical testing and constant immersion testing showed differing trends.

International Journal of Polymeric Materials and Polymeric Biomaterials, 2014

ABSTRACT Nano-biocomposites composed of poly (lactide-co-glycolide) (PLGA) and chitosan (CS) were... more ABSTRACT Nano-biocomposites composed of poly (lactide-co-glycolide) (PLGA) and chitosan (CS) were electrospun using two fabrication methods. In the single nozzle method, the CS nano-powders dispersed in PLGA solutions were electrospun through a single nozzle but in the double-nozzle method, PLGA and CS were simultaneously electrospun from two syringes and the electrospun PLGA nanofiber and electrosprayed CS nanoparticles were mixed and collected on the rotating drum (randomly oriented [A] and aligned [B]) to prepare the nano-biocomposite membrane. The PLGA/CS scaffolds were prepared at the different ratios. The single-nozzle method was associated with decreasing fiber diameter when the CS content was increased and exhibited improve mechanical and hydrophilic properties.

Materials and Corrosion

Coating disbondments on pipeline steels are regions with high resistivity where conventional cath... more Coating disbondments on pipeline steels are regions with high resistivity where conventional cathodic protection (CP) could not fully protect. Therefore, in an attempt to mitigate this challenge, this study investigates the effect of pulse CP on corrosion mitigation and electrochemical conditions under a simulated coating disbondment on X‐52 pipeline steel. In this regard, conventional and pulse CP of −870 mVSCE were applied to the open mouth of a simulated coating disbondment. For pulse CP, frequencies of 1, 5, and 10 kHz were used. Results showed while the conventional CP was not able to fully protect the 20 cm simulated coating disbondment, for the pulse CP with increase in frequency from 1 to 5 kHz, and from 5 to 10 kHz, improve in CP potential protection under the simulated coating disbondment was achieved. This was accompanied by considerably lower corrosion and a more uniform pH distribution under the simulated coating disbondment.

Recent excavations in Tepe Sagzabad in Qazvin Plain, Iran, yielded some archaeological metal arti... more Recent excavations in Tepe Sagzabad in Qazvin Plain, Iran, yielded some archaeological metal artifacts dating to the Early Iron Age. Among different metal fragments, a small tube was found. As a part of systematic analytical research, thin sheet tube was studied for elemental composition, manufacturing technique and deterioration mechanism using optical microscopy (OM), scanning electron microscopy combined with energy dispersive X-ray spectroscopy (SEM-EDS) and Raman spectroscopy. The results of analyses showed that the tube has been made from a thin sheet Cu-Sn alloy. In addition, it was found that the tube was completely mineralized, and there was no sound metal remained in it. Corrosion of the tube was composed of a bilayer structure in which the original shape of the artifact has been preserved. Raman characterization of the corrosion products showed that the inner layer is composed mainly of cupric oxide (tenorite) beneath an outer cuprous oxide layer (cuprite) which has grown...

ECS Meeting Abstracts, 2015

Hybrid supercapacitors, or briefly pseudocapacitors, are an emerging class of energy storage devi... more Hybrid supercapacitors, or briefly pseudocapacitors, are an emerging class of energy storage devices, with the capability of providing both high power and energy density. In contrast to conventional electric double layer capacitors, which accumulate charge mostly through an electrostatic mechanism, pseudocapacitors utilize the pseudocapacitance arising from reversible Faradic reactions occurring at the electrode surface [1]. Although various metal oxides have been investigated as active material for pseudocapacitors, greater attention has been given to manganese oxides. In recent years, also Mn-based binary oxides have been studied for pseudocapacitance, in particular, mixed oxides comprising Ni or Co as the other component [2-4] In the present work, Mn-Ni oxide thin films were deposited potentiodynamically at scan rate of 100 mVs-1, pH=7 and room temperature, on a stainless steel substrate. Undoubtedly, a survey of the literature shows that a systematic study on the effect of opera...