Investigation on the effect of nano-ceria on the epoxy coatings for corrosion protection of mild steel in natural seawater

2018 ◽  
Vol 65 (1) ◽  
pp. 38-45 ◽  
Author(s):  
Joseph Raj Xavier
Keyword(s):  
Charge Transfer ◽  
Mild Steel ◽  
Charge Transfer Resistance ◽  
Epoxy Coating ◽  
Coated Sample ◽  
Natural Seawater ◽  
Film Resistance ◽  
Transfer Resistance ◽  
Content Type ◽  
Nano Ceria

Purpose This paper aims to investigate the effect of introducing nano-ceria (CeO2) particles to the epoxy coatings on mild steel in natural seawater. Design/methodology/approach The epoxy–ceria nanoparticles were coated with mild steel using a wire-wound draw-down bar method. The effects of ceria nanoparticles on the corrosion resistance of epoxy-coated samples were analyzed using scanning electrochemical microscopy (SECM) and electrochemical impedance spectroscopy (EIS). Findings Localized measurements such as oxygen consumption and iron dissolution were observed using SECM in natural seawater in the epoxy-coated sample. The increase in film resistance (Rf) and charge transfer resistance (Rct) values by the addition of nano-ceria particles in the epoxy coating was measured from EIS measurements after wet and dry cyclic corrosion test. Scanning electron microscope (SEM)/energy dispersive X-ray spectroscope (EDX) analysis showed that complex oxides of nano-ceria were enriched in corrosion products at a scratched area of the coated mild steel after corrosion testing. Focused ion beam-transmission electron microscope (FIB-TEM) analysis confirmed the presence of the nanoscale oxide layers of ceria in the rust of the steel. Research limitations/implications The tip current at −0.70 V for the epoxy–CeO2-coated sample decreased rapidly because of cathodic reduction of the dissolved oxygen. The increase in film resistance (Rf) and charge transfer resistance (Rct) values by the addition of nano-ceria particles in the epoxy coating were measured from EIS measurements after wet and dry cyclic corrosion test. Practical implications The presence of complex oxide layers of nano-ceria layers protects the coated steel from rusting. Social implications The use of this nano-ceria for corrosion protection is environment-friendly. Originality/value The results of this study indicated the significant effect of nano-ceria particles on the protective performance and corrosion resistance of the epoxy coating on mild steel. The dissolution of Fe2+ was lower in the epoxy–ceria nanoparticle-coated mild steel than that of the epoxy-coated mild steel resulting in a lower anodic current of steel. The increase in film resistance and the charge transfer resistance showed that the nano-ceria particles and the formation of complex oxides provide better barrier protection to the coating metal surfaces.

Corrosion performance of mild steel and epoxy coated rebar in concrete under simulated harsh environment

2019 ◽  
Vol 37 (5) ◽  
pp. 657-678
Author(s):  
Muazzam Ghous Sohail ◽  
Mohammad Salih ◽  
Nasser Al Nuaimi ◽  
Ramazan Kahraman
Keyword(s):  
Mild Steel ◽  
Polarization Resistance ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Charge Transfer Resistance ◽  
Harsh Environment ◽  
Corrosion Performance ◽  
Transfer Resistance ◽  
Content Type ◽  
Rc Structures

Purpose The purpose of this paper is to present the results of a two-year long study carried out in order to evaluate the corrosion performance of mild steel bare bars (BB) and epoxy-coated rebar (ECR) in concrete under a simulated harsh environment of chlorides. Design/methodology/approach The blocks are subjected to Southern Exposure testing. The electrochemical impedance spectroscopy (EIS), linear polarization resistance (LPR) and Tafel plot are performed to measure the polarization resistance and corrosion current densities of these rebars. Knife-peel test was performed to assess the adhesion between epoxy and underlying steel after two years of exposure. Findings Mild steel BB showed a high corrosion current density of 1.24 µA/ cm2 in Tafel plots and a very low polarization resistance of 4.5 kΩ cm2 in LPR technique, whereas very high charge transfer resistance of 1672 and 1675 kΩ cm2 is observed on ECR and ECR with controlled damage (ECRCD), through EIS technique, respectively. EIS is observed to be a suitable tool to detect the defects in epoxy coatings. After two years of immersion in 3.89 percent NaCl− solution, the mild steel BB were severely corroded and a considerable weight loss was observed, whereas under heavy chloride attack, ECR showed no deterioration of epoxy coating and neither any corrosion of underlying steel. Results of this study show that the durability of reinforced concrete (RC) structures with respect to corrosion could be enhanced by using ECR, especially in harsh climatic conditions. Originality/value The corrosion performance of mild steel and ECR in concrete under a simulating splash zone environment is evaluated. EIS was used to evaluate the health of epoxy and corrosion state of underneath steel rebars. EIS was able to detect the defects in epoxy. The durability of RC structures could be enhanced in harsh climate regions by using ECR.

BENIGN APPROACH OF CANTHIUM PARVIFLORUM AS A BIOINHIBITOR FOR MILD STEEL CORROSION IN 0.5 M H2SO4 MEDIUM

2020 ◽  
Vol 27 (09) ◽  
pp. 1950208
Author(s):  
K. A. KARTHICK ◽  
D. S. BHUVANESHWARI ◽  
D. UMAPATHI ◽  
PANDIAN BOTHI RAJA
Keyword(s):  
Charge Transfer ◽  
Mild Steel ◽  
Electrochemical Impedance ◽  
Measurement Techniques ◽  
Charge Transfer Resistance ◽  
Effect Of Temperature ◽  
Adsorption Model ◽  
Free Energy Of Adsorption ◽  
Transfer Resistance ◽  
Vis Spectroscopy

Canthium parviflorum leaf extract (CPLE) was utilized for corrosion prevention against mild steel (MS) in 0.5[Formula: see text]mol[Formula: see text]L[Formula: see text] H2SO4 test medium. Standard corrosion measurement techniques (gravimetric and electrochemical) were employed for this purpose. Gravimetric tests clearly confirmed that the prepared CPLE efficiently performs as corrosion inhibitor. Potentiodynamic polarization measurements (PPM) and electrochemical impedance spectroscopy (EIS) measurements were performed in order to analyze the charge transfer process of CPLE. Polarization curves indicate that CPLE acts through mixed mode inhibition. Impedance study reveals that the CPLE additives enhances the charge transfer resistance values and conversely decreases values of double layer capacitance. Scanning electron microscopy (SEM), Ultraviolet-Visible (UV-Vis) spectroscopy analysis and Fourier-Transform Infrared spectroscopy (FTIR) were done to confirm the Fe-CPLE complex formation on MS. The effect of temperature reveals that the inhibition efficiency increases with decrease in temperature and increase in concentration of CPLE (maximum of 4[Formula: see text]mg[Formula: see text]L[Formula: see text]). The adsorption of CPLE shows that it obeys Langmuir’s isotherm model with free energy of adsorption, [Formula: see text][Formula: see text]kJ mol[Formula: see text]. A suitable adsorption model is also proposed.

Rebar corrosion behavior of coral aggregate seawater concrete by electrochemical techniques

2020 ◽  
Vol 67 (1) ◽  
pp. 59-72 ◽  
Author(s):  
Zhangyu Wu ◽  
Hongfa Yu ◽  
Haiyan Ma ◽  
Bo Da ◽  
Yongshan Tan
Keyword(s):  
Stainless Steel ◽  
Charge Transfer ◽  
Linear Regression ◽  
Polarization Resistance ◽  
Electrochemical Techniques ◽  
Charge Transfer Resistance ◽  
Coated Steel ◽  
Linear Regression Equation ◽  
Transfer Resistance ◽  
Content Type

Purpose Coral aggregate seawater concrete (CASC) is a new type of lightweight aggregate concrete that is becoming widely used in reef engineering. To investigate the corrosion behavior of different kinds of rebar in CASC exposed to simulated seawater for 0-270 d, the electrochemical techniques, including linear polarization resistance (LPR) technique and the electrochemical impedance spectroscopy (EIS), were used in the present work. Design/methodology/approach The electrochemical techniques, including LPR technique and the EIS, were used in the present work. Findings Based on the time-varying law of linear polarization curves, self-corrosion potential (Ecorr), polarization resistance (Rp), corrosion current density (Icorr), corrosion rate (i), and the characteristics of EIS diagrams for different types of rebar in CASC, it can be found that the anti-corrosion property of them can be ranked as epoxy resin coated steel > 2205 duplex stainless steel (2205S) > 316 L stainless steel (316 L) > organic coated steel > ordinary steel. Additionally, the linear regression equation between Rp and charge transfer resistance (Rct) was established. Finally, the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC. Originality/value The linear regression equation between polarization resistance and charge transfer resistance was established. And the EIS corrosion standard of rebar was established from the LPR corrosion standard, which provides a direct standard for the EIS technique to determine the condition of rebar in CASC.

scholarly journals Effect of nanostructured carbon coatings on the electrochemical performance of Li1.4Ni0.5Mn0.5O2+ x -based cathode materials

2016 ◽  
Vol 7 ◽  
pp. 1960-1970 ◽  
Author(s):  
Konstantin A Kurilenko ◽  
Oleg A Shlyakhtin ◽  
Oleg A Brylev ◽  
Dmitry I Petukhov ◽  
Alexey V Garshev
Keyword(s):  
Diffusion Coefficient ◽  
Charge Transfer ◽  
Specific Capacity ◽  
Charge Transfer Resistance ◽  
Poly Vinyl Alcohol ◽  
Nanostructured Carbon ◽  
Transfer Resistance ◽  
Carbon Coatings ◽  
Lithium Diffusion Coefficient ◽  
Electrochemical Cycling

Nanocomposites of Li1.4Ni0.5Mn0.5O2+ x and amorphous carbon were obtained by the pyrolysis of linear and cross-linked poly(vinyl alcohol) (PVA) in presence of Li1.4Ni0.5Mn0.5O2+ x . In the case of linear PVA, the formation of nanostructured carbon coatings on Li1.4Ni0.5Mn0.5O2+ x particles is observed, while for cross-linked PVA islands of mesoporous carbon are located on the boundaries of Li1.4Ni0.5Mn0.5O2+ x particles. The presence of the carbon framework leads to a decrease of the polarization upon cycling and of the charge transfer resistance and to an increase in the apparent Li+ diffusion coefficient from 10−16 cm2·s−1 (pure Li1.4Ni0.5Mn0.5O2+ x ) to 10−13 cm2·s−1. The nanosized carbon coatings also reduce the deep electrochemical degradation of Li1.4Ni0.5Mn0.5O2+ x during electrochemical cycling. The nanocomposite obtained by the pyrolysis of linear PVA demonstrates higher values of the apparent lithium diffusion coefficient, a higher specific capacity and lower values of charge transfer resistance, which can be related to the more uniform carbon coatings and to the significant content of sp2-hybridized carbon detected by XPS and by Raman spectroscopy.

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