scholarly journals The Effect of Graphene on the Protective Properties of Water-Based Epoxy Coatings on Al2024-T3

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
T. Monetta ◽  
A. Acquesta ◽  
A. Carangelo ◽  
F. Bellucci
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Electrochemical Impedance ◽  
Free Water ◽  
Adsorbed Water ◽  
Polymerization Process ◽  
Protective Properties ◽  
Matrix Interaction ◽  
Graphene Nanoflakes ◽  
Water Based ◽  
Pathway Length

0.5 and 1% wt. of graphene nanoflakes were added to an anticorrosive additives-free water-based epoxy resin applied to Al2024-T3 samples. Calorimetric (DSC) and adhesion (cross-cut test) tests indicated that the presence of graphene did not affect the polymerization process of the resin or its adhesion to the substrate while it had some effect on its wettability. Electrochemical Impedance Spectroscopy (EIS) results obtained suggested that the addition of a small amount of graphene greatly enhanced the protective properties of the epoxy coating, retarding electrolytes absorption and reducing the total amount of adsorbed water. The latter occurrence suggests that the graphene effect on coating performances is related to both extended diffusion pathway length and graphene/matrix interaction due to the unique properties of graphene.

Aging Behavior of Polyaspartic Polyurea under Salt-Fog Exposure Studied by Electrochemical Impedance Spectroscopy

2012 ◽  
Vol 455-456 ◽  
pp. 760-764
Author(s):  
Wei Bo Huang ◽  
Jing Zhang ◽  
Xin Mao Li ◽  
Ping Lu
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Coating Thickness ◽  
Electrochemical Impedance ◽  
Great Influence ◽  
Low Frequency ◽  
Curing Temperature ◽  
Aging Behavior ◽  
Protective Properties ◽  
Salt Fog

- Electrochemical impedance spectroscopy (EIS) was used to study the thickness and curing temperature influence on the aging behavior of polyaspartic ester (PAE) polyurea under salt fog exposure in this paper. The result has demonstrated that coating thickness and curing temperature had great influence on aging behavior of the PAE-t-HDI prepolymer-D2000H65 aliphatic polyurea (T3). The low frequency impedance after 1day exposure increased from 5.31×1010Ω·cm to 7.96×1010Ω while coating thickness was increased from 40μm to 200μm, and the low frequency impedance of 200μm coating was 7.42×1010Ω·cm2 high after 200 days exposure. The low frequency impedance after 1day and 200 days exposure increased by 0.83×1010 Ω·cm2 and 0.39×109Ω·cm2 respectively, while curing temperature were increased from 60°C to 80°C. Suggestions have been made, namely that increase the coating thickness and curing temperature can improve low frequency impedance of PAE polyurea, as a result, improve the protective properties of the coatings.

Bicarbonate, Temperature, and pH Influences on the Passivation of API-X100 Pipeline Steel in Simulated Groundwater Solutions

2014 ◽  
Author(s):  
Ibrahim M. Gadala ◽  
Akram Alfantazi
Keyword(s):  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Passive Film ◽  
Electrochemical Impedance ◽  
Pipeline Steel ◽  
Environmental Parameters ◽  
Passive Films ◽  
Good Correspondence ◽  
Protective Properties ◽  
X100 Pipeline Steel

The influence of bicarbonate ion (HCO3−) concentration and related environmental parameters such as pH and temperature on the passivation of API-X100 pipeline steel is the focus of this investigation. NS4 solution simulating groundwater trapped under disbonded coatings at regions where near-neutral stress corrosion cracking (SCC) occurs was used as a reference. Bicarbonate content in the solutions was increased steadily and the critical HCO3− concentration at which passivation becomes evident is found using potentiodynamic polarization sweeps. Multi-step dissolution is observed especially in higher pH solutions, owing to the involvement of hydroxide ions (OH−) in the adsorption of hydrous Fe(OH)2. Dynamic electrochemical impedance spectroscopy (DEIS) is used to study and compare interfacial processes in active, pre-passive, passive, and trans-passive regions. The results of the potentiodynamic and DEIS tests achieve good agreement. The protective properties of the passive film formed at three different HCO3− concentrations (critical passivation and two higher concentrations) and temperatures (25, 50, and 75 °C) are studied. The combined effect of HCO3− and temperature resulted in a pH range from ∼6.7 to 9.3 for the nine conditions in the corresponding test matrix. Passive films were formed at a suitable anodic potential and then studied with electrochemical impedance spectroscopy (EIS), Mott-Schottky, and cyclic voltammetry (CV) tests. Evidence of adsorption and diffusion, in addition to significant resistance from the passive film, is observed and accounted for in the equivalent circuit, which achieved good correspondence when fitted with the experimental data. The protective properties of the overall passive film are enhanced with increased bicarbonate and decreased temperature. Positive slopes in the Mott-Schottky plots reveal the n-type semi-conductive behavior of the passive films in all conditions and the CV results highlight the proposed reaction sequences occurring in different potential scan regions. CV measurements also confirm the enhanced protective properties of passive films with increased bicarbonate and lower temperatures observed in the EIS analysis.

A Bayesian View on the Hilbert Transform and the Kramers-Kronig Transform of Electrochemical Impedance Data: Probabilistic Estimates and Quality Scores

2020 ◽  
Author(s):  
Jiapeng Liu ◽  
Ting Hei Wan ◽  
Francesco Ciucci
Keyword(s):  
Power Generation ◽  
Electrochemical Impedance Spectroscopy ◽  
Hilbert Transform ◽  
Electrochemical Impedance ◽  
The Self ◽  
Impedance Data ◽  
The Hilbert Transform ◽  
Validation Tests ◽  
Self Consistency ◽  
Mathematical Relations

<p>Electrochemical impedance spectroscopy (EIS) is one of the most widely used experimental tools in electrochemistry and has applications ranging from energy storage and power generation to medicine. Considering the broad applicability of the EIS technique, it is critical to validate the EIS data against the Hilbert transform (HT) or, equivalently, the Kramers–Kronig relations. These mathematical relations allow one to assess the self-consistency of obtained spectra. However, the use of validation tests is still uncommon. In the present article, we aim at bridging this gap by reformulating the HT under a Bayesian framework. In particular, we developed the Bayesian Hilbert transform (BHT) method that interprets the HT probabilistic. Leveraging the BHT, we proposed several scores that provide quick metrics for the evaluation of the EIS data quality.<br></p>

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