Showing 9 results for Impedance
Pakshir M., Amini R.,
Volume 2, Issue 1 (3-2005)
Abstract
Anodes are critical component of cathodic protection systems. As part of this effort, three different anodes were tested in a cathodic protection system that was designed and constructed to prevent further corrosion of reinforced concrete. This anodic system includes an electrically conductive coating composition applied in fluid form over an outer surface of the concrete mix. The composition further includes a predetermined amount of electrically conductive carbon material (coke, carbon black, graphite) uniformly distributed in the epoxy resin (as a binder) whereby the coating composition has a predetermined value of resistively. This investigation attempts to find the best type and optimum content of conductive carbon filler in poxy coating, to ensure optimal anode working parameters for marine environments (basically marine and sewer environments) and if any of the coating systems tested in this study excel over the other. In this study, electric and electrochemical parameters of three layer (with average coating thickness of 300µm) coke-epoxy, carbon black-epoxy and graphite-epoxy conducting paints (with different amount of filler) have been determined during long-term anodic polarization (70 days) in a seawater solution. During this test, on the basis of impedance measurements, the electrical resistances of these coatings have been calculated every 14 days. if conductive paints exhibit good electric and electrochemical stability, they will be attractive for cathodic protection of reinforced concrete.
N. Eslami Rad*, Ch. Dehghanian,
Volume 7, Issue 4 (10-2010)
Abstract
Abstract: Electroless Nickel (EN) composite coatings embedded with Cr2O3 and/or MoS2 particles were deposited to combine the characters of both Cr2O3 and MoS2 into one coating in this study. The effects of the co-deposited particles on corrosion behavior of the coating in 3.5% NaCl media were investigated. The results showed that both Ni-P and Ni-P composite coatings had significant improvement on corrosion resistance in comparison to the substrate. Codeposition of Cr2O3 in coating improved corrosion characteristic but co-deposition of MoS2 decreased corrosion resistance of the coating.
Z. Shahri, S. R. Allahkaram,
Volume 10, Issue 4 (12-2013)
Abstract
Metal matrix nano composite coatings possess enhanced properties such as corrosion and wear resistance. This paper aims to study the corrosion behavior of pure Co and Co-BN nano composite coatings deposited with different particles concentration (5-20 g L-1) on copper substrates using electroplating technique. Morphology and elemental compositions of the coatings were investigated by means of scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS). The corrosion behavior was analyzed in a 3.5 wt% NaCl via polarization and impedance techniques. The results obtained in this study indicate that the co-deposition of BN nano particles improved corrosion resistance of electrodeposited cobalt coatings.
N. Bahrami Panah, N. Ajami,
Volume 13, Issue 1 (3-2016)
Abstract
The epoxy coatings containing multi-walled carbon nanotube/ poly ortho aminophenol nanocomposite were prepared and used as anticorrosive coatings. The nanocomposites with different contents of carbon nanotube were synthesized in a solution of sodium dodecyl sulfate and ammonium peroxy disulfate as a surfactant and an oxidant, respectively. The morphology and structural properties were confirmed by Fourier transform infrared spectroscopy and scanning electron microscopy methods. The mean size of nanocomposite particles was 20-35 nm determined by scanning electron microscopy. The epoxy coatings containing the nanocomposites were applied over mild steel panels and their corrosion performance was investigated using electrochemical impedance spectroscopy and potentiodynamic polarization measurements in a 3.5 % sodium chloride solution. The results showed that epoxy coatings consisting of nanocomposite with 1 wt.% multi-walled carbon nanotube exhibited higher anticorrosive properties than other prepared coatings of different carbon nanotube contents, which could be due to the strong interaction between the mild steel surface and the conjugated nanocomposite.
M. R. Khorram, M. R. Shishesaz, Iman Danaee, D. Zaarei,
Volume 13, Issue 1 (3-2016)
Abstract
The micro layers micaceous iron oxide and nano-TiO 2 were incorporated into the epoxy resin by mechanical mixing and sonication process. Optical micrographs showed that the number and diameter size of nanoparticle agglomerates were decreased by sonication. The structure and composition of the nanocomposite was determined using transmission electron microscopy which showed the presence of dispersed nano-TiO 2 in the polymer matrix. The anticorrosive properties of the synthesized nano-composites coating were investigated using salt spray, electrochemical impedance spectroscopy and polarization measurement. The EIS results showed that coating resistance increased by addition of micaceous iron oxide micro layers and nano-TiO 2 particles to the epoxy coatings. It was observed that higher corrosion protection of nanocomposite coatings obtained by the addition of 3 %wt micaceous iron oxide and 4%wt nano-TiO 2 into epoxy resin.
A. Ehsani, S Bodaghi, H Mohammad Shiri, H Mostaanzadeh, M Hadi,
Volume 13, Issue 3 (9-2016)
Abstract
In this study, an organic compound inhibitor, namely N-benzyl-N-(4-chlorophenyl)-1H-tetrazole-5-amine (NBTA), was synthesized and the role of this inhibitor for corrosion protection of stainless steel (SS) exposed to 0.5 M H2SO4 was investigated using electrochemical, and quantum analysis. By taking advantage of potentiodynamic polarization, the inhibitory action of NBTA was found to be mainly mixed type with dominant anodic inhibition. The effectiveness of the inhibitor was also indicated using electrochemical impedance spectroscopy (EIS). Moreover, to provide further insight into the mechanism of inhibition, quantum chemical calculations of the inhibitor were performed. The adsorption of NBTA onto the SS surface followed the Langmuir adsorption model with the free energy of adsorption ΔG0ads of of -7.88 kJ mol-1. Quantum chemical calculations were employed to give further insight into the mechanism of inhibition action of NBTA.
M. R. Ghaani, P. Marashi,
Volume 15, Issue 3 (9-2018)
Abstract
Na super ionic conductive (NASICON) materials are ceramics with three-dimensional scaffolds. In this study, Li1.4Al0.4Ti1.6(PO4)3 with NASICON structure was synthesized by Pechini method. As a result, a sample having a total conduction of 1.18×10-3 S cm-1 was attained. In addition, various parameters were studied to obtain high value of conductivity, by optimizing the process. The optimization was made using L16 Taguchi based orthogonal array, followed by ANOM, ANOVA and stepwise regression. As a result, the optimum synthesis parameters can be obtained, while pH of the solution was adjusted to 7. The ratio between the concentration of citric acid to metal ions and ethylene glycol concentration stuck to 1 and 2.5, respectively. The best heat treatment can be carried out with a combination of pyrolysis at 600 ºC and sintering at 1000 ºC.
Mozhgan Hirbodjavan, Arash Fattah-Alhosseini, Hassan Elmkhah, Omid Imantalab,
Volume 19, Issue 4 (12-2022)
Abstract
The principal goal of this research is to produce a CrN/Cu multilayer coating and a CrN single-layer
coating and also compare their electrochemical and antibacterial behavior. In this investigation, the coatings were
applied to the stainless steel substrate by cathodic arc evaporation a sub-division of physical vapor deposition
(CAE-PVD). The present phases were characterized and the thickness of the coatings was measured using X-ray
diffraction (XRD) and field emission scanning electron microscopy (FE-SEM), respectively. Rockwell-C tester was
used to evaluate the adhesion quality. Also, to evaluate the mechanical properties of the coatings such as modulus
of elasticity and hardness, a nanoindentation test was used and the indentation effect and coating topography were
evaluated using atomic force microscopy (AFM). Studying the electrochemical behavior of the coatings was done
using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) tests in Ringer's
solution. The results of EIS tests showed that the CrN coating had higher polarization resistance in comparison to
the CrN/Cu coating and an increasing trend of polarization resistance related to both coatings was identified by
rising the time of immersion. Also, using the PDP curves, the CrN and CrN/Cu coating current densities were
estimated at 1.835×10-8 and 2.088×10-8, respectively. The antibacterial activity of CrN and CrN/Cu coatings was
evaluated by the spot-inoculation method. The results of the antibacterial test indicated that compared to CrN
coating, CrN/Cu coating had a better impact on the control of the bacteria growth.
Bijan Eftekhari Yekta, Omid Banapour Ghafari,
Volume 20, Issue 4 (12-2023)
Abstract
Glasses in the B2O3-Li2 (O, Cl2, I2) system were prepared through the conventional melt-quenching method. Then, the conductivity of the molten and glassy states of these compositions was evaluated. Furthermore, the thermal and crystallization behavior of the glasses was determined using simultaneous thermal analysis (STA) and X-ray diffractometry (XRD). The electrical conductivity of the melts was measured at temperatures ranging from 863 to 973 K, and the activation energy of the samples was calculated using the data obtained from ion conduction in the molten state and found to be in the vicinity of 32 kcal/mol. In glassy states, electrical conductivity was also measured. To determine this property, the electrochemical impedance spectroscopy method (EIS) was used. In the molten state, temperature played an important role in the ion conductivity; however, at lower temperatures, other factors became important. Based on the results, the addition of LiI and LiCl to the B2O3-Li2O base glass system (75 B2O3, 10 Li2O, 7.5 LiI, 7.5 LiCl) (mol%) increases the ionic conductivity of the glass from 3.2 10-8 S.cm-1 to 1.4 10-7 S.cm-1 at 300 K.
