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Hot corrosion behavior and near-surface microstructure of a “low-temperature high-activity Cr-aluminide” coating on inconel 738LC exposed to Na2SO4, Na2SO4 + V2O5 and Na2SO4 + V2O5 + NaCl at 900 °C
, Article Corrosion Science ; Volume 128 , 2017 , Pages 42-53 ; 0010938X (ISSN) ; Ghasemi, B ; Sadrnezhaad, S. K ; Habibollahzadeh, A ; Jafarzadeh, K ; Sharif University of Technology
Abstract
Hot corrosion is a serious problem in gas turbines due to poor quality fuels which contain Na, V, S and Cl. To resolve the problem, Cr-aluminide was coated on IN-738LC superalloy with a two steps pack cementation process. Oxidation behavior and near-surface microstructure of the coating showed consecutive increase in destruction by exposition to Na2SO4, 75Na2SO4 + 25 V2O5 and 70Na2SO4 + 25 V2O5 + 5NaCl (wt.%). Kinetic studies indicated parabolic corrosion rate in salt-less samples due to diffusion. Similar expression for salt-covered samples was assessed for oxide dissolution. Plate-like, broken-plate-like and cauliflower-like morphologies attributed to the corrosion products were observed...
Epoxy nanocomposite coatings with enhanced dual active/barrier behavior containing graphene-based carbon hollow spheres as corrosion inhibitor nanoreservoirs
, Article Corrosion Science ; Volume 185 , 2021 ; 0010938X (ISSN) ; Ramazani Saadatabadi, A ; Mahdavian, M ; Arjmand, M ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
Graphene-based carbon hollow spheres (CHSs) fabrication, doped with 2-mercaptobenzimidazole (MBI) was successfully done in previous work. The active/barrier corrosion protection performance (CPP) of epoxy coatings was evaluated using salt spray test, electrochemical impedance spectroscopy (EIS), and scanning vibrating electrode technique (SVET). Results proved the active/barrier CPP enhancement of epoxy coatings in the presence of 3 wt. % MBI@CHSs. While the presence of MBI and empty CHSs in epoxy coatings did not further improve the active performance. An improvement in the adhesion loss of the epoxy coating, ca. 58 %, was observed in the presence of 3 wt. % MBI@CHSs. © 2021
Investigation on corrosion stratigraphy and morphology in some iron age bronze alloys vessels by OM, XRD and SEM–EDS methods
, Article Applied Physics A: Materials Science and Processing ; Volume 122, Issue 4 , 2016 ; 09478396 (ISSN) ; Hasanpour, A ; Davami, P ; Sharif University of Technology
Abstract
The recently study of the corrosion in some bronze artefacts from the Sangtarashan Iron Age site, western Iran, was established to identify corrosion morphology and mechanism in these objects. The corrosion layers in 22 samples were studied by optical microscopy, scanning electron microscopy–energy-dispersive X-ray spectroscopy and X-ray diffraction methods. The results showed that a thin corrosion crust has formed on the surface of bronzes with a triple-layer structure, including two internal and one external corrosion layers. The formation of these layers is due to copper leaching from the bronze surface. The internal corrosion part has been a compact, tin-rich corrosion/oxidation product...
Ni-P/Zn-Ni compositionally modulated multilayer coatings – part 2: corrosion and protection mechanisms
, Article Applied Surface Science ; Volume 442 , 2018 , Pages 313-321 ; 01694332 (ISSN) ; Ghorbani, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
The Ni-P/Zn-Ni compositionally modulated multilayer coatings CMMCs were electrodeposited from a single bath by switching the deposition current density. The corrosion resistance of the deposits was studied and compared with that of monolayers of Ni-P and Zn-Ni alloys via Tafel polarization, EIS and salt spray tests. Characterization of corrosion products by means of EDS and XRD revealed more details from the corrosion mechanism of the monolayers and multilayers. The corrosion current density of Ni-P/Zn-Ni CMMCs were around one tenth of Zn-Ni monolayer. The CMMC with incomplete layers performed lower polarization resistance and higher corrosion current density compared to the CMMC with...
Epoxy nanocomposite coating based on calcium zinc phosphate with dual active/barrier corrosion mitigation properties
, Article Progress in Organic Coatings ; Volume 163 , 2022 ; 03009440 (ISSN) ; Haddadi, S. A ; Motlagh, A. L ; Ghaderi, M ; Ramezanzadeh, B ; Mahdavian, M ; Arjmand, M ; Jalili, M ; Sharif University of Technology
Elsevier B.V
2022
Abstract
In this paper, a high-performance epoxy nanocomposite with dual active/barrier protection ability based on calcium zinc phosphate (CZP) nanopigment was fabricated. Then chemistry, morphology, and anti-corrosion ability of the commercial zinc phosphate (ZP) and CZP pigments were studied. By electrochemical techniques, the inhibition potency of the CZP nanopigment was examined in a NaCl solution on mild steel (MS) substance and compared with that of ZP. Results revealed a higher corrosion inhibition degree of the CZP compared to the ZP. The growth of a protective layer on the metal coupons exposed to the CZP extract was illustrated by X-ray photoelectron spectroscopy (XPS), field emission...
A detailed atomic level computational and electrochemical exploration of the Juglans regia green fruit shell extract as a sustainable and highly efficient green corrosion inhibitor for mild steel in 3.5 wt% NaCl solution
, Article Journal of Molecular Liquids ; Volume 284 , 2019 , Pages 682-699 ; 01677322 (ISSN) ; Alibakhshi, E ; Bahlakeh, G ; Ramezanzadeh, B ; Mahdavian, M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Seawater, which has been frequently applied in cooling and injection water systems, imposes severe pitting corrosion to mild steel. Addition of green and sustainable inhibitors based on renewable sources is one of the promising methodologies for restricting metal corrosion in chloride-containing electrolytes. In this study, for the first time, from both theoretical and experimental faces, the role of Juglans regia green fruit shell (JRS) extract as a sustainable potent corrosion inhibitor for mild steel was studied. The chemical structure of the JRS extract was deliberated by Fourier transform infrared spectroscopy (FT-IR). By electrochemical techniques including polarization, EIS and...
PH-Sensitive polydopamine–La (III) complex decorated on carbon nanofiber toward on-demand release functioning of epoxy anti-corrosion coating
, Article Langmuir ; Volume 38, Issue 38 , 2022 , Pages 11707-11723 ; 07437463 (ISSN) ; Saadatabadi, A. R ; Mahdavian, M ; Haddadi, S. A ; Sharif University of Technology
American Chemical Society
2022
Abstract
The high aspect ratio and unique thermal and electrical characteristics of carbon nanofiber (CNF) made it an ideal physical barrier against the penetration of corrosive ions. However, the poor compatibility of the CNF with the polymer matrix and the lack of active corrosion inhibitors are the key limitations of this nanomaterial, resulting in short-term anti-corrosion resistance. An intelligent self-healing epoxy (EP) coating, including CNF modified with a polydopamine (PDA)-La3+ complex, was successfully fabricated to overcome these issues. Electrochemical impedance spectroscopy (EIS) evaluation implied that mild steel (MS) submerged in a 3.5 wt % NaCl solution containing the CNF-PDA-La...
The Effect of Inhibitors on the Corrosion of Automotive Aluminum in Water and Ethylene Glycol Environment
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
In this study, the effects of different corrosion inhibitors on the corrosion of aluminum alloy which is used in the cooling systems of automotive industries were investigated. Also a comparison between the corrosion behaviour of the mentioned aluminum alloy with and without any galvanic connection to 5 different metals consist of solder, stainless steel, mild steel, brass and copper was done. The corrosion rate became more by establishing galvanic coupling. The base solution was ethylene glycol and water which is the base part of all antifreeze compounds. The tests were done at high temperature about 88ºC. Two different industrial corrosion inhibitors were examined in these conditions....
Evaluation of the Effect of Olive Leaf Extract (Olive Leaf) as a Green Inhibitor on Corrosion of Concrete Steel Reinforcements in the Persian Gulf Sea Water Simulator
, M.Sc. Thesis Sharif University of Technology ; Afshar, Abdollah (Supervisor)
Abstract
In this project, olive leaf extract has been investigated as a green corrosion inhibitor or in other words environmentally friendly for rebars embedded in concrete in the Persian Gulf Sea water simulator. Olive leaves were prepared by ultrasonic method at 50 ° C with the help of ethanol solvent. The water-ethanol solvent was 70:30 and the resulting extract was immediately applied to the concrete mix in specified doses. Portland cement type 2 according to ISIRI-389-96 standard has been used to prepare concrete. The resulting extract powder was added to the samples in four different doses: 2%, 4%, 6%, 8% by weight of cement to prove the inhibitory function as well as the cathodic or inhibitory...
Failure analysis of a gas turbine marriage bolt
, Article Journal of Failure Analysis and Prevention ; Volume 7, Issue 2 , 2007 , Pages 81-86 ; 15477029 (ISSN) ; Salimi, H. R ; Sharif University of Technology
2007
Abstract
A gas turbine which output 18MW power exploded after 3h of ordinary operation and after 4,785 starts. The turbine's rotor had undergone repair after 77,000 operating hours. A piece was cut from the failed marriage bolt and tested using atomic absorption spectrometry in order to know the grade of the alloy. It was found that the marriage bolt is made from ASTM A193 B16 steel which is suitable. Hardness and microhardness measurement was also determined and showed that it was within the range of the specified hardness for ASTM A193 B16 steel. The marriage bolt's mechanical properties also meet technical specifications and showed that it contained anti-corrosion properties. Visual examination...
Cluster/polarized continuum models for density functional theory investigations of benzimidazole corrosion inhibitors at metal/solution interface
, Article Corrosion ; Volume 62, Issue 3 , 2006 , Pages 199-206 ; 00109312 (ISSN) ; Arshadi, M. R ; Parsafar, Gh. A ; Sastri, U. S ; Sharif University of Technology
National Assoc. of Corrosion Engineers International
2006
Abstract
The molecular behavior of some benzimidazole (C7H 6N2) derivatives as corrosion inhibitors ojiron in hydrochloric acid (HCl) solution was investigated quantum electrochemically via the inhibitors' chemical potential (μ), molecular softness (σ), and the extent of charge transfer from the inhibitor to the metal (ΔN). These quantities were obtained from density functional theory (DFT) calculations for three models, i.e., isolated inhibitors (in vacua), inhibitors in solution, and, finally, inhibitors in electrical double layer (EDL). In these models, the effects of solvent, substrate, and electric field were considered using a polarized continuum model, iron Fe13(9,4) cluster, and a...
A simple and fast method for comparison of corrosion inhibition powers between pairs of pyridine derivative molecules
, Article Corrosion ; Volume 61, Issue 8 , 2005 , Pages 778-783 ; 00109312 (ISSN) ; Arshadi, M. R ; Parsafar, Gh. A ; Sharif University of Technology
National Assoc. of Corrosion Engineers International
2005
Abstract
Ab initio quantum chemical calculations at the density functional theory (DFT) level were performed on eight pyridine derivative molecules as corrosion inhibitors for iron in an acidic solution. In this regard, the geometry of the molecules were optimized using the B3LYP/6-31G method first, and then interactions of these optimized structures with the iron atom were explored using the B3LYP/LANL1MB method. Two modes of adsorption were considered, i.e., planar adsorption (P) via the pyridine ring and vertical adsorption (V) through a nitrogen atom. The interaction energy was minimized through the variation of the inhibitor molecule-iron atom distance. These minimum energy values, along with...
The Structure and Corrosion Behavior of Synthesized Zn-SiO2 Nano-composite Coating by Sol-Gel Method
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
Zinc–silicanano-composite coatings were produced by successive dip coatand sintering procedure from different sol-gel solutions. The surface and cross-sectional morphologies of Zn-SiO2 nano-particles (NPs) were examined using field emission scanning electron microscopy (FE-SEM). Corrosion resistance evaluated by means of polarization and electrochemical impedance spectroscopy showed that even thin films of Zn-SiO2 in orders of 200 nm can have corrosion rates as low as conventional hot dip galvanized steels. Multi-layers coatings have been studied and showed that 10 layers coating with the thickness of 2m has the lowest corrosion rate with the passive region in anodic branch. Corrosion...
Microstructure-corrosion resistance relationship of Direct and Pulse Current electrodeposited Zn-TiO2 nanocomposite coatings
, Article Ceramics International ; Vol. 41, issue. 1 , 2014 , pp. 217-224 ; ISSN: 02728842 ; Ghorbani, M ; Afshar, A ; Sharif University of Technology
Abstract
Zinc-TiO2 nano-composite coatings were synthesized by Direct Current (DC) and Pulse Current (PC) electrodeposition techniques. The effects of the plating parameters on the microstructure, codeposition percentage of TiO2 and corrosion behavior were investigated. The coatings morphology presents hexagonal grains perpendicularly oriented to the surface. Under DC conditions, TiO2 content of the coatings decreased with increasing TiO2 concentration of the electrolyte. Increasing applied current and TiO2 concentration in the bath leads to a fine microstructure with corrosion currents as low as 2.7 μA/cm2. Under PC conditions, incorporation rate of nanoparticles tends to increase with increasing...
Double layer bioglass-silica coatings on 316L stainless steel by sol-gel method
, Article Ceramics International ; Volume 40, Issue 1, Part A , January 2014 , Pages 993–1000 ; Afshar, A ; Sharif University of Technology
Abstract
The application of bioglass coatings on metallic implants provides link between bone and materials and prevents corrosion of metallic implants in body fluid. Therefore, in this research, 45S5 bioglass-silica coatings on 316L stainless steel were prepared by the sol-gel method and were characterized by different techniques. According to X-ray diffraction (XRD) results, by sintering 45S5 bioglass at 600 C for 5 h, coatings containing both amorphous phase and Na2Ca2Si3O9 crystalline phase were obtained. Scanning electron microscopy (SEM) results showed that coatings prepared via appropriate sol aging and substrate preparations are crack-free. Potentiodynamic polarization tests in simulated body...
Micro-stratigraphical investigation on corrosion layers in ancient Bronze artefacts by scanning electron microscopy energy dispersive spectrometry and optical microscopy
, Article Heritage Science ; Volume 1, Issue 1 , 2013 ; 20507445 (ISSN) ; Emami, S. M ; Ahmadi, H ; Davami, P ; Sharif University of Technology
2013
Abstract
Background: Archaeological metallic artefacts buried in soils deteriorate by means of various environmental as well as internal factors and mechanisms over time such as change in composition and microstructure of metal and corrosive factors due to long-term burial environment. Corrosion in metals occurs in different morphologies and results in different types of corrosion products based on soil composition. Identification of corrosion mechanisms and morphology in archaeological metals can help conservators to characterize deterioration occurred in metals and make decisions to protect artefacts about preventing further deterioration. In archaeological bronzes, different layers may form on the...
The corrosion investigation of rebar embedded in the fibers reinforced concrete
, Article Construction and Building Materials ; Volume 35 , October , 2012 , Pages 564-570 ; 09500618 (ISSN) ; Akil, H. M ; Dolati, A ; Rouhi, J ; Sharif University of Technology
Elsevier
2012
Abstract
One effective method for preventing corrosion of steel reinforcement and improving the mechanical properties of concrete is changing the physical nature of concrete by adding different materials. In this study, we have used polypropylene fibers as an additional material. We have compared the corrosion rate of rebar using different volume ratios and sizes of polypropylene fibers. Reinforcement potential increased as the amount of fibers increased from 0 to 2 kg m -3. The polypropylene fibers delay the initial corrosion process by preventing cracking, thereby decreasing permeability of the concrete. In addition, the corrosion rate of concrete samples made with Kish Island coral aggregate was...
The enhancing power of iodide on corrosion prevention of mild steel in the presence of a synthetic-soluble Schiff-base: Electrochemical and surface analyses
, Article Electrochimica Acta ; Volume 55, Issue 20 , August , 2010 , Pages 6058-6063 ; 00134686 (ISSN) ; Arshadi, M. R ; Miandari, S ; Sharif University of Technology
Abstract
The inhibitory action of N,N′-1,3-propylen-bis(3- methoxysalicylidenimine) {PMSI} on mild steel corrosion in sulfuric acid medium was investigated through electrochemical methods and evaluations based on infrared spectroscopy and scanning electron micrographs. The studies revealed that the molecule is a good mixed-type inhibitor (mostly anodic), acts as a multi-dentate ligand and repels the corrosive agents by hydrophobic forces. Its adsorption on metal surface has a physicochemical nature and obeys the Langmuir isotherm. At a critical (optimum) concentration, an anomalous inhibitory behavior was observed and interpreted at microscopic level by means of desorption/adsorption process and...
Experimental and theoretical studies of media effects on copper Corrosion in acidic environments containing 2-amino-5-mercapto-1,3,4-thiadiazole
, Article Journal of the Iranian Chemical Society ; Volume 7, Issue 2 , June , 2010 , Pages 478-486 ; 1735207X (ISSN) ; Arshadi, M.R ; Biglar, M ; Sharif University of Technology
2010
Abstract
Corrosion behaviour of copper metal in acid solutions (HCl, H 2SO4 and H3PO4) containing 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) was investigated experimentally and theoretically via gravimetric, potentio-dynamic and quantum electrochemical approaches. Similar behavior was observed for H2SO4 and H3PO4 media, and related to the nature of anions at metal/solution interface. With regard to HCl, however, the rate of corrosion was determined to be low at initial stages, but high later on using an auto-catalyzing mechanism. In the presence of AMT, the experimental studies revealed that this molecule was a good anodic-type inhibitor causing substantial changes in corrosion potential. Moreover,...
An investigation of the corrosion behavior of some iron artifacts belonging to the early Iron Age
, Article International Journal of Conservation Science ; Volume 9, Issue 2 , 2018 , Pages 277-290 ; 2067533X (ISSN) ; Dolati, A ; Emami, M ; Sharif University of Technology
Universitatea "Alexandru Ioan Cuza" din Iasi
2018
Abstract
The corrosion process of two iron dagger handles decorated with bronze strips found from the Ziviyeh area, which is one of the important Iron Age sites in the northwest of Iran, is thoroughly investigated. X-ray radiography was used to obtain the damages and corrosion zones of the artifact. Optical and scanning electron microscopies were used to study the microstructure of cross sections and to achieve structural details about the metal matrix and corrosion layers. The X-ray diffraction method was used to study the chemical characterization of corrosion products. The results of studies have shown that severe stress on bronze strips is caused by the formation of goethite and lepidocrocite...