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1 – 10 of 797
Article
Publication date: 27 June 2008

Mohammad Ghassem Mahjani, Mohammad Sabzali, Majid Jafarian and Jaber Neshati

The purpose of this paper is to investigate the effects of inorganic inhibitors on the corrosion rate of aluminum alloy using the electrochemical noise (EN) analysis and…

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Abstract

Purpose

The purpose of this paper is to investigate the effects of inorganic inhibitors on the corrosion rate of aluminum alloy using the electrochemical noise (EN) analysis and electrochemical impedance spectroscopy (EIS) techniques.

Design/methodology/approach

EN and EIS measurements were employed to study the corrosion behavior of aluminum alloy in Na2SO4(0.50 M)/NaCl(0.20 M) solution in presence of inorganic inhibitors. The time‐series noise patterns were transformed into the frequency domain using fast Fourier transformation, and then their power spectrum densities (PSDs) at specified frequencies were determined and compared with the EIS and polarization results.

Findings

The EN, EIS and polarization results were in agreement. The inhibitive effect of the anions decreased in the order: CrO42−>Cr2O72−>NO3>WO42−>MoO42−>NO2. The results showed that the slope of PSD of the current (i.e. the “roll off”) was less where inhibition efficiency was greater. The spectral noise impedance and the modulus of the impedance recorded using impedance spectroscopy showed good agreement.

Originality/value

This paper provides useful information relative to corrosion inhibition efficiency of the sodium and potassium salts using EN analysis technique.

Details

Anti-Corrosion Methods and Materials, vol. 55 no. 4
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 12 January 2010

S. Krakowiak and K. Darowicki

The purpose of this paper is to present the investigation of aluminum alloy by means of dynamic electrochemical impedance spectroscopy (DEIS), which is simultaneous method of AC…

Abstract

Purpose

The purpose of this paper is to present the investigation of aluminum alloy by means of dynamic electrochemical impedance spectroscopy (DEIS), which is simultaneous method of AC impedance and DC polarization measurements.

Design/methodology/approach

A method of DEIS has been applied. Changes in equivalent circuit (EC) parameters versus potential for both investigated aluminium alloys are evaluated.

Findings

On the basis of obtained results, it is unambiguously demonstrated that the addition of 4.5 percent magnesium degraded the anticorrosive properties of the test alloys. It is difficult to define unequivocally the range of passive state and a moment of passive layer breakdown on the basis of current/voltage dependencies. However, application of the DEIS method and analysis of the evolution of particular elements of an electrical EC allowed identification of the instant of corrosion process initiation.

Practical implications

The presented method is only suitable for laboratory evaluation of metal alloys because it requires sophisticated measuring equipment and is a difficult and time‐consuming way to obtain final results.

Originality/value

In one experiment, both polarization (DC) data and impedance (AC) measurements can be obtained. This allows the electrochemical properties of very similar aluminum alloys to be compared precisely with one other.

Details

Anti-Corrosion Methods and Materials, vol. 57 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 8 January 2020

Zhiping Zhu, Chun Shi, Yu Zhang and Zhifeng Liu

The purpose of this paper is to study the effects of Cl and direct stray current on the soil corrosion of three grounding grid materials.

Abstract

Purpose

The purpose of this paper is to study the effects of Cl and direct stray current on the soil corrosion of three grounding grid materials.

Design/methodology/approach

The electrochemical corrosion properties of three grounding grid materials, which include the Q235 steel, Q235 galvanized flat steel and copper, were measured by means of the weak polarization curve method and electrochemical impedance spectroscopy; the corrosion rate of specimens was calculated using the weight loss method; and the specimen surfaces were characterized using the scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analysis.

Findings

Results showed that both factors, Cl and direct stray current, can accelerate the corrosion rate of grounding grid materials. The magnitude of DC stray current density affected the mass transfer type and response frequency of the anode and cathode reaction of grounding materials, while the Cl contents of the soil only affect the mass transfer rate of the electrode material from the electrochemical impedance spectroscopy diagrams. The electric field generated by the DC stray current caused Cl directed migration. The larger the DC stray current density, the greater the diffusion process and the greater the weight loss rate of the grounding grid materials that would have a logarithmic relationship with the Cl content at the same DC stray current density. The corrosion resistance of the three materials is copper > Q235 galvanized flat steel > Q235 flat steel.

Originality/value

The paper provides information regarding the relationship among Cl, direct stray current and corrosion of three grounding grid materials by means of electrochemical impedance spectroscopy. Meanwhile the weight loss rate is the logarithmic relationship with the Cl content, which is useful for understanding the corrosion mechanism of Q235 steel, Q235 galvanized flat steel and copper under the condition of Cl and direct stray current in soil.

Details

Anti-Corrosion Methods and Materials, vol. 67 no. 1
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 19 September 2019

Elbahi Djaalab, Mohamed Elhadi Samar, Saida Zougar and Rochdi Kherrat

A new electrochemical analysis based on ß-cyclodextrin (ß-CD) was developed for penicillin V (Peni-V) using polyaniline as a conducting polymer.

Abstract

Purpose

A new electrochemical analysis based on ß-cyclodextrin (ß-CD) was developed for penicillin V (Peni-V) using polyaniline as a conducting polymer.

Design/methodology/approach

The preparation of modified electrode involves the incorporation of β-CD with membrane of polyaniline. Polyaniline, incorporating β-CD, was prepared by electrochemical polymerization method in a medium of hypochloride. Cyclic voltammetry and electrochemical impedance have been used to characterize this sensor. The detection and the kinetic study of modified platinum electrode are evaluated.

Findings

Results clearly indicate that β-CDs interfere with the polymerization mechanism with an inhibition factor. The inclusion phenomenon of β-CDs has been studied and applied to detect Peni-V. The principle of this electrochemical sensor is based on the chemical properties of β-CD, which were studied using the cyclic voltammetric method and impedance spectroscopy. The electrochemical behavior of Peni-V at concentrations between 10–8 and 10–2 M was measured versus Ag/AgCl at pH 7.4 and 30°C in a phosphate alkaline buffer. Relationship of Peni-V concentration in logarithmic mathematical form with current in potentiometric method and with resistance in impedimetric method were obtained.

Originality/value

The present study showed that the Pt electrode modified with Polyaniline–β-CD was an excellent candidate for sensitive penicillin analysis. The proposed electroanalytical technique is rapid, simple and inexpensive.

Details

Sensor Review, vol. 40 no. 2
Type: Research Article
ISSN: 0260-2288

Keywords

Article
Publication date: 16 March 2022

Iling Aema Wonnie Ma, Sachin Sharma Ashok Kumar, Ramesh Kasi, Ammar Shafaamri and Ramesh Subramaniam

This study aims to propose that the corrosion resistance of the neat epoxy coating can be further enhanced by incorporating reinforcing agents.

Abstract

Purpose

This study aims to propose that the corrosion resistance of the neat epoxy coating can be further enhanced by incorporating reinforcing agents.

Design/methodology/approach

Chitosan, silica and their hybrid compound were used to study the subject of corrosion resistance of epoxy coating systems. This work used 3.5 Wt.% NaCl solution as the electrolyte, and electrochemical impedance spectroscopy (EIS) was used to investigate the electrochemical behaviour of the studied coating systems. Standard and accelerated states were used without and with scratch on the coating layer.

Findings

It was found that the impedance value of composite coating incorporated with the hybrid compound was significantly higher at 1010 Ω after 14 days of exposure in both testing states. The breakpoint frequency (fb) determination also proves with large capacitive region at low-to-high frequency of impedance plots corresponding to the high corrosion resistance.

Originality/value

The hybrid compound consisting of chitosan as organic biopolymer and silica as inorganic material, respectively, served as a promising reinforcing agent for composite coating as a promising corrosion inhibitor. Different states of EIS measurement were used which are standard (without scratch) and accelerated (with scratch) states associated with the fb values.

Details

Pigment & Resin Technology, vol. ahead-of-print no. ahead-of-print
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 3 November 2014

N.A. Mat Nor, L. Ismail, S.K.M. Jamari, K. Ramesh, B. Vengadaesvaran and A.K. Arof

This paper aims to analyse the coating behaviour in corrosion environment as well as to evaluate the best percentage amount of copper oxide and copper needed for organic coating…

Abstract

Purpose

This paper aims to analyse the coating behaviour in corrosion environment as well as to evaluate the best percentage amount of copper oxide and copper needed for organic coating in order to prevent the corrosion degradation. Electrochemical impedance spectroscopy (EIS) studies have been conducted in order to evaluate the corrosion performance of polyester-epoxy-copper oxide and polyester-epoxy-copper coating systems.

Design/methodology/approach

The availability of this modem instruments is used to obtain impedance data as well as computer programs to interpret the results that made the technique popular. In addition, EIS is well suited to the study of polymer-coated metals.

Findings

The results showed that samples containing 25 weight per cent of copper oxide and copper (90P25CuO and 90P25Cu) obtained the excellent corrosion properties from the first day up to 30 days of NaCl immersion. The highest corrosion resistance values obtained by 90P25CuO and 90P25Cu on the 30th day were 7.107 × 108 O and 5.701 × 108 O, respectively, with lower double layer capacitance of 1.407 × 10−9 Farad and 3.935 × 10−9 Farad, respectively. Moreover, the water uptake gained by these two coating samples was the lowest at the end of immersion, which was 0.0084 for 90P25CuO and 0.1592 for 90P25Cu, showing that the sample has good corrosion performance.

Originality/value

This paper discussed on the highest corrosion resistance, double layer capacitance and the water uptake of the copper (Cu) and copper oxide (CuO) coating system obtained from the EIS measurements.

Details

Pigment & Resin Technology, vol. 43 no. 6
Type: Research Article
ISSN: 0369-9420

Keywords

Article
Publication date: 20 August 2019

Kong Weicheng, Shen Hui, Gao Jiaxu, Wu Jie and Lu Yuling

This study aims to investigate the electrochemical corrosion performance of high velocity oxygen fuel (HVOF) sprayed WC–12Co coating in 3.5 Wt.% NaCl solution, which provided a…

Abstract

Purpose

This study aims to investigate the electrochemical corrosion performance of high velocity oxygen fuel (HVOF) sprayed WC–12Co coating in 3.5 Wt.% NaCl solution, which provided a guiding significance on the corrosion resistance of H13 hot work mould steel.

Design/methodology/approach

A WC–12Co coating was fabricated on H13 hot work mould steel using a HVOF, and the electrochemical corrosion behaviors of WC–12Co coating and substrate in 3.5 Wt.% NaCl solution was measured using open circuit potential (OCP), potentiodynamic polarization curve (PPC) and electrochemical impedance spectroscopy (EIS) tests.

Findings

The OCP and PPC of WC–12Co coating positively shift than those of substrate, its corrosion tendency and corrosion rate decrease to enhance its corrosion resistance. The curvature radius of capacitance curve on the WC–12Co coating is larger than that on the substrate, and the impedance and polarization resistance of WC–12Co coating increase faster than those of substrate, which reduces the corrosion process.

Originality/value

The electrochemical corrosion behaviors of WC–12Co coating and substrate in 3.5 Wt.% NaCl solution is first measured using OCP, PPC and EIS tests, which improve the electrochemical corrosion resistance of H13 hot work mould steel.

Article
Publication date: 1 September 1993

V. Ambrosi and A. Di Sarli

An electrochemical impedance spectroscopy technique based on an equivalent circuit used for the evaluation of metallic substratum/organic coating/electrolyte systems as well as…

Abstract

An electrochemical impedance spectroscopy technique based on an equivalent circuit used for the evaluation of metallic substratum/organic coating/electrolyte systems as well as the importance of each parameter and the way to calculate it is analysed. It is emphasised that the classical semi circumference in the complex plot, which describes the response of a parallel RC circuit, is not real axis centred. This fact makes it necessary to consider the organic film and electrochemical double layer capacitance as pseudo‐capacitances which depend on a fractional power of the frequency. Starting from mathematical relationships over the total impedance algorithms based on the least squares methods are proposed to fit experimental data requiring less processing time than iterative techniques. The methodology is described analysing the charge transfer resistance, ionic resistance and dielectric capacitance variation at increasing immersion times for naval steel/chlorinated rubber (with different PVC)/artificial sea water systems. Parameters thus obtained correlate well with the naval steel/organic coating deterioration with time, also determined by using corrosion potential measurements and visual assessment.

Details

Anti-Corrosion Methods and Materials, vol. 40 no. 9
Type: Research Article
ISSN: 0003-5599

Article
Publication date: 28 July 2022

Yida Liu, Jie Zhao, Xiaoyu Yang, Yanhong Gu and Zihao Yang

The purpose of this paper is to improve the corrosion resistance of the 6061-Al alloy as the battery pack material for electric vehicles, and the nano-SiC/MAO composite coating…

Abstract

Purpose

The purpose of this paper is to improve the corrosion resistance of the 6061-Al alloy as the battery pack material for electric vehicles, and the nano-SiC/MAO composite coating was prepared.

Design/methodology/approach

The corrosion resistance of coatings was evaluated by the global electrochemical test, and the local electrochemical impedance spectroscopy (LEIS) was used to study the local corrosion mechanism. The laser confocal microscope, scanning electron microscope and X-ray diffractometer (XRD) were used to characterise coatings.

Findings

Results showed that the impedance of nano-SiC/MAO coating was 1–2 times higher than MAO coating, and the main corrosion product was Al(OH)3. LEIS results showed that the impedance of the nano-SiC/MAO coating was two times higher than the MAO coating. The defective SiC/Micro-arc oxidation coating still had high corrosion resistance compared to the MAO coating.

Originality/value

The physical model of the local corrosion mechanism for SiC/MAO composite coating in “cavity-fracture collapse” mode was proposed.

Details

Anti-Corrosion Methods and Materials, vol. 69 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

Article
Publication date: 1 December 2001

Stefan Krakowiak, Kazimierz Darowicki and Jacek Bordzilowski

A method has been proposed for testing rubber linings in industrial conditions based on a proposed model of coating penetration. The depth of penetration of rubber lining by water…

Abstract

A method has been proposed for testing rubber linings in industrial conditions based on a proposed model of coating penetration. The depth of penetration of rubber lining by water has been determined on the basis of investigation results by electrochemical impedance spectroscopy. Verification of the proposed procedure has been performed by comparing the obtained results of electrochemical investigations with determination of the water content in rubber by the gravimetric method. It has been confirmed that the values calculated in accordance with the penetration model correlate with the water content in rubber. Investigation results confirm views on the corrosion aggressiveness of media in different zones of a scrubber working as part of the flue gas desulphurisation installation.

Details

Anti-Corrosion Methods and Materials, vol. 48 no. 6
Type: Research Article
ISSN: 0003-5599

Keywords

1 – 10 of 797