scholarly journals Protection of Carbon Steel Rebars by Epoxy Coating with Smart Environmentally Friendly Microcapsules

Coatings ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 113
Author(s):  
Jacob Ress ◽  
Ulises Martin ◽  
Juan Bosch ◽  
David M. Bastidas

The protection of mild steel by modified epoxy coating containing colophony microencapsulated corrosion inhibitors was investigated in this study. The corrosion behavior of these epoxy coatings containing colophony microcapsules was studied by electrochemical analysis using cyclic potentiodynamic polarization and electrochemical impedance spectroscopy. The microcapsule coating showed decreased corrosion current densities of 2.75 × 10−8 and 3.21 × 10−8 A/cm2 along with corrosion potential values of 0.349 and 0.392 VSCE for simulated concrete pore solution and deionized water with 3.5 wt.% NaCl, respectively, indicating improved corrosion protection in both alkaline and neutral pH. Electrochemical impedance spectroscopy analysis also showed charge transfer resistance values over one order of magnitude higher than the control sample, corroborating the electrochemical corrosion potential and current density testing results. Overall, the use of colophony microcapsules showed improved corrosion protection in simulated concrete pore solution and DI water solutions containing chloride ions.

2011 ◽  
Vol 105-107 ◽  
pp. 1797-1800
Author(s):  
Yu Ye Xu ◽  
Bi Lan Lin

Electrochemical impedance spectroscopy (EIS) technique was used to investigate the corrosion behavior of HRB400 reinforcing steel in Simulated Concrete Pore (SCP) solutions differently contaminated by bicarbonate ions and/or chloride ions. The corrosion kinetics parameters of the capacitance Y0-CPEdl, surface roughness n0-CPEdl and charge transfer resistance Rct of the electric double-layer capacitance of the interface of solution/HRB400 were analyzed and were compared to those of HPB235 reinforcing steel. The results show that the corrosion resistance index of HRB400 and HPB235 is increased with an increase in NaCl content to 0.1%, but that is decreased markedly for a larger NaCl content; and that of them is decreased largely with an increase in pH; the decrease extent of the corrosion resistance index of HRB400 with NaCl or pH is larger than that of HPB235; and the corrosion resistance of HRB400 is inferior to that of HPB235.


Author(s):  
Nguyen Tuan Anh ◽  
Ngo Thi Hoa ◽  
To Thi Xuan Hang ◽  
Nguyen Thuy Duong ◽  
Trinh Anh Truc

Abstract: Zinc aluminum hydrotalcite containing 2-benzothiazolythio-succinic acid (HT-BTSA) and modified by 2-aminoethyl-3-aminopropyltrimethoxysilane (APS) at different concentrations (3%, 5% and 10%). APS modified HT-BTSA (HT-BTSA-S) was incorporated in epoxy coatings at 3% concentration. The corrosion protective performance of the epoxy coatings containing HT-BTSA-S were evaluated by electrochemical impedance spectroscopy, adhesion measurement.  The results showed that the presence of HT-BTSA-S improved protection performance of epoxy coating and the best protection was obtained with HT-BTSA modified with 5 % APS.  


Sensors ◽  
2021 ◽  
Vol 21 (3) ◽  
pp. 788
Author(s):  
Hien T. Ngoc Le ◽  
Sungbo Cho

Aggregation of amyloid-β (aβ) peptides into toxic oligomers, fibrils, and plaques is central in the molecular pathogenesis of Alzheimer’s disease (AD) and is the primary focus of AD diagnostics. Disaggregation or elimination of toxic aβ aggregates in patients is important for delaying the progression of neurodegenerative disorders in AD. Recently, 4-(2-hydroxyethyl)-1-piperazinepropanesulfonic acid (EPPS) was introduced as a chemical agent that binds with toxic aβ aggregates and transforms them into monomers to reduce the negative effects of aβ aggregates in the brain. However, the mechanism of aβ disaggregation by EPPS has not yet been completely clarified. In this study, an electrochemical impedimetric immunosensor for aβ diagnostics was developed by immobilizing a specific anti-amyloid-β (aβ) antibody onto a self-assembled monolayer functionalized with a new interdigitated chain-shaped electrode (anti-aβ/SAM/ICE). To investigate the ability of EPPS in recognizing AD by extricating aβ aggregation, commercially available aβ aggregates (aβagg) were used. Electrochemical impedance spectroscopy was used to probe the changes in charge transfer resistance (Rct) of the immunosensor after the specific binding of biosensor with aβagg. The subsequent incubation of the aβagg complex with a specific concentration of EPPS at different time intervals divulged AD progression. The decline in the Rct of the immunosensor started at 10 min of EPPS incubation and continued to decrease gradually from 20 min, indicating that the accumulation of aβagg on the surface of the anti-aβ/SAM/ICE sensor has been extricated. Here, the kinetic disaggregation rate k value of aβagg was found to be 0.038. This innovative study using electrochemical measurement to investigate the mechanism of aβagg disaggregation by EPPS could provide a new perspective in monitoring the disaggregation periods of aβagg from oligomeric to monomeric form, and then support for the prediction and handling AD symptoms at different stages after treatment by a drug, EPPS.


2015 ◽  
Vol 227 ◽  
pp. 515-518 ◽  
Author(s):  
Luigi Calabrese ◽  
Lucio Bonaccorsi ◽  
Chiara Borsellino ◽  
Angela Caprì ◽  
Francesca Fabiano ◽  
...  

In this work the assessment of the corrosion performances in saliva solution of NdFeB magnets coated with silane layers was studied for its application in orthodontic brackets. The silane film, deposited by dip coating technique, has been prepared with varying dipping steps, with the purpose to identify the number of layers able to achieve an optimal protective action. Corrosion protection performance, during immersion in Fusayama synthetic saliva solution, was evaluated by means electrochemical impedance spectroscopy (EIS). The silane coatings evidenced good barrier properties resulting in an improvement of the anti-corrosion performances of the magnets. Better results were observed for samples with at least 15 layers of silane, that evidenced still acceptable protective action after three days of immersion in a Fusayama synthetic saliva solution.


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