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1 – 10 of 430Muazzam Ghous Sohail, Mohammad Salih, Nasser Al Nuaimi and Ramazan Kahraman
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…
Abstract
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.
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Ali Ehsani, Mohammad Ghasem Mahjani, Maryam Nasseri and Majid Jafarian
The purpose of this paper was to investigate the anti-corrosion behavior of polypyrrole (PPy) films in different states and presence of alumina nanoparticles synthesized by…
Abstract
Purpose
The purpose of this paper was to investigate the anti-corrosion behavior of polypyrrole (PPy) films in different states and presence of alumina nanoparticles synthesized by galvanostatic electropolymerization on stainless steel (SS) electrodes in an artificial seawater solution using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS).
Design/methodology/approach
The electrochemical measurements were used to examine the effects of PPy and its nanocomposite on the corrosion behavior of SS type 316L in artificial seawater. A standard electrochemical cell with three electrodes was used for the measurements. The electrochemical response of the coated electrodes in the doped and the undoped state was compared with that of a bare electrode. Corrosion rate information was obtained by the Tafel extrapolation method, where the intersection point of a cathodic and an anodic polarization curve provides both the corrosion potential and the corrosion current. EIS measurements confirmed the potentiodynamic and open circuit potential (OCP) results. The microstructure of the obtained films was investigated by scanning electron microscopy.
Findings
The results showed that the coated polymer films shifted the electrode potential toward more positive potentials, but this shift did not lead to passivation. However, a notable synergy was observed between PPy undoped film, oxygen reduction and iron dissolution. The potential of the SS remained in the active dissolution region, and it was not possible to produce a passive oxide layer in this region. PPy separates the metal dissolution process from the oxygen reduction process. This would prevent the local pH increase at the metal surface and subsequent delamination. The polarization curves, EOCP and impedance measurements showed that PPy undoped/Al2O3 layers show promise as good candidates for the corrosion protection of reactive metals.
Originality/value
This paper presents that electrodes coated with undoped PPy synthesized in the presence of dodecyl sulfate anions and Al2O3 nanoparticles offered a noticeable enhancement of protection against corrosion processes.
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The purpose of this paper is to investigate the corrosion resistance of SiO2-Al2O3 coating on mild steel.
Abstract
Purpose
The purpose of this paper is to investigate the corrosion resistance of SiO2-Al2O3 coating on mild steel.
Design/methodology/approach
SiO2-Al2O3 was coated using sol-gel method, and electrochemical measurements were applied to assess the performance of the coated steel.
Findings
The main conclusion is that SiO2-Al2O3-coated specimens acquired a higher corrosion resistance than that of uncoated specimen. icorr values of the coated specimens were between 12 and 14 times smaller than those of uncoated specimen. The coated specimens exhibited a higher Rcor value at electrochemical impedance spectroscopy analysis. The high values of Rcor and low values of CPEdl observed within the SiO2-Al2O3-coated samples imply an improved anti-corrosion capability.
Originality/value
In this work, there are three points of originality. First, steel specimens were coated with ormosil-based solution by applying sol-gel dip coating method. Second, both SiO2 and Al2O3 coatings were applied simultaneously at a considerably low temperature, i.e. 200 °C. Finally, the performance of the coated materials against wet corrosion was improved significantly.
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Ayssar Nahlé, Ideisan Abu‐Abdoun and Ibrahim Abdel‐Rahman
The purpose of this paper is to study electrochemically and by weight loss experiments the effect of 4‐vinylbenzyl triphenyl phosphonium chloride on the corrosion inhibition of…
Abstract
Purpose
The purpose of this paper is to study electrochemically and by weight loss experiments the effect of 4‐vinylbenzyl triphenyl phosphonium chloride on the corrosion inhibition of mild steel in 1.0 M HCl solution, which will serve researchers in the field of corrosion.
Design/methodology/approach
Electrochemical and weight loss measurements were carried out on carbon steel specimens in 1.0 M HCl and in 1.0 M HCl containing various concentrations (1.0 × 10−7 to 1.0 × 10−4 M) of the laboratory synthesized 4‐vinylbenzyl triphenyl phosphonium chloride at temperatures ranging from 303 to 343 K.
Findings
4‐vinylbenzyl triphenyl phosphonium chloride was found to be a highly efficient inhibitor for carbon steel in 1.0 M HCl solution, reaching about 99 per cent at the concentration of 1 × 10−4 M at room temperature and about 96 per cent at 303 K, a concentration and temperature considered to be very moderate. The percentage of inhibition in the presence of this inhibitor was decreased with temperature which indicates that physical adsorption was the predominant inhibition mechanism because the quantity of adsorbed inhibitor decreases with increasing temperature.
Practical implications
This inhibitor could have application in industries, where hydrochloric acid solutions at elevated temperatures are used to remove scale and salts from steel surfaces, such as acid cleaning of tankage and pipeline, and may render dismantling unnecessary.
Originality/value
This paper is intended to be added to the family of phosphonium salt corrosion inhibitors which are highly efficient and can be employed in the area of corrosion prevention and control.
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Illustrates how potentiodynamic anodic polarization measurement conventions can be applied to electrochemical measurements in corrosion testing following the standard ASTM G5–87…
Abstract
Illustrates how potentiodynamic anodic polarization measurement conventions can be applied to electrochemical measurements in corrosion testing following the standard ASTM G5–87 and G3–89. Provides information for electrochemical corrosion data acquisition in a standard presentation format, making comparison easy with curves found in the literature or between data from different laboratories.
Gongwen Tang, Tingting Ren, Yi Wang, Zhishan Yan, Linrong Ma, Xiangyu Hou and Xin Huang
The purpose of this paper is to study the effect of the nano tube fillers on the corrosion protection properties of the self-curing epoxy (SEP) coatings.
Abstract
Purpose
The purpose of this paper is to study the effect of the nano tube fillers on the corrosion protection properties of the self-curing epoxy (SEP) coatings.
Design/methodology/approach
The self-curing epoxy (SEP) resin was synthesized via a reaction between diisopropoxy-bis ethylacetoacetato titanate and the epoxy resin. Halloysite nanotubes (HNTs) was surface modified by grafting (3-glycidoxypropyl) trimethoxysilane to obtain modified HNTs (mHNTs). The HNTs and mHNTs are used as nano tube fillers for the SEP coating. The thermal stability of the coatings was assessed via thermo-gravimetric analysis. The field-emission scanning electron microscopy (SEM) was conducted to analyze the surfaces and cross sections of the coatings. The anticorrosive efficiencies of the coatings were investigated by electrochemical measurements and a neutral salt spray test.
Findings
The results demonstrated that the additions of HNTs and mHNTs have little effect on the thermal degradation temperature of the SEP coating. However, the addition of the nanotubes reduced the corrosion resistance of the SEP coating.
Originality/value
The SEP coating itself showed excellent corrosion resistance without any reinforcement particles and is hence promising for application in the heavy-duty anticorrosion field of heat exchangers.
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Yan Jun Xi, Yong Jun Liu, Zhi Xin Wang and Jin Bin Liu
The purpose of this paper is to investigate the high‐temperature oxidation behavior in air at 900‐1,000°C and electrochemical corrosion performance in 3.5 percent NaCl solution of…
Abstract
Purpose
The purpose of this paper is to investigate the high‐temperature oxidation behavior in air at 900‐1,000°C and electrochemical corrosion performance in 3.5 percent NaCl solution of Ti‐24Al‐17Nb‐0.5Mo (at. %) alloy with Ti‐48Al‐8Cr‐2Ag (at. %) coating.
Design/methodology/approach
Laboratory tests are performed to determine the effect of the Ti‐48Al‐8Cr‐2Ag (at. %) coating on the corrosion performance of Ti3Al alloy.
Findings
It is found that the oxidation rate of sputtered Ti‐48Al‐8Cr‐2Ag nanocrystalline coating is lower than that of the Ti3Al alloy at 900°C. The former forms a scale of merely Al2O3 and the latter forms a scale of TiO2. However, the Ti‐48Al‐8Cr‐2Ag nanocrystalline coating shows a slightly higher oxidation rate than did the Ti3Al alloy at 1,000°C, because outer TiO2 scale forms and columnar boundaries of the coating give a larger actual oxidation area than the original alloy. The coating shows the excellent electrochemical corrosion resistance in 3.5 percent NaCl solution because it exhibits stable passive polarization behavior without any overpassivation phenomena.
Originality/value
TiAlCrAg coatings may become a promising protective coating for Ti3Al‐base intermetallics, which improve the Al2O3 scale formation and make the passivation stable.
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A.K. Mishra, R. Balasubramaniam and S. Tiwari
The research work in this paper aims to focus on understanding the corrosion inhibition of 6061‐8 (vol.%) SiC in 3.5 per cent NaCl solution using different concentrations (250…
Abstract
Purpose
The research work in this paper aims to focus on understanding the corrosion inhibition of 6061‐8 (vol.%) SiC in 3.5 per cent NaCl solution using different concentrations (250, 500, 750 and 1,000 ppm) of cerium and lanthanum chloride.
Design/methodology/approach
The corrosion inhibition of 6061‐SiC in 3.5 per cent NaCl solution using the rare earth chloride inhibitors was analyzed by different electrochemical techniques. The techniques employed were linear polarization, Tafel extrapolation and electrochemical impedance spectroscopy (EIS). Further, surface characterization, before and after inhibitor addition, was studied using scanning electron microscopy (SEM) and energy dispersive analysis using X‐ray.
Findings
It was observed that the polarization resistance increased after addition of LaCl3 and CeCl3, with maximum increase noticed for 250 ppm LaCl3 and 1,000 ppm CeCl3. CeCl3 addition showed better improvement in polarization resistance value compared with LaCl3 addition. Pitting nucleation resistance also increased with addition of LaCl3 and CeCl3, with maximum obtained for 250 ppm LaCl3 and 500 ppm CeCl3. EIS studies showed that there was a significant increase in resistance of areas not covered by the surface film after addition of LaCl3 and CeCl3, when compared with the case without inhibitor, with a maximum increase observed with 1,000 ppm CeCl3. Rare earth chloride addition resulted in an increase in resistance on both cathodic intermetallic sites as well as the pitted regions by formation of precipitates of their oxide/hydroxide on those locations. This gave the high pitting nucleation resistance as well as improved corrosion resistance.
Research limitations/implications
It was observed that optimum concentrations of CeCl3 and LaCl3 resulted in good corrosion resistance properties on 6061‐SiC in 3.5 per cent NaCl solutions. Even small quantities of these inhibitors resulted in high corrosion resistance. However, it should be noted that both LaCl3 and CeCl3 did not follow a simple increase in corrosion resistance with composition, despite both being rare earth chloride inhibitors, and this issue merits further research.
Practical implications
Metal matrix composites (MMC) are of great use in the aerospace, military and automotive industries due to their good mechanical strength/density and stiffness/density ratios. A typical example might be the reinforcement of Al alloys with SiC particulates, which leads to a new generation of engineering materials. However, the addition of a reinforcing phase can cause discontinuities in any protective surface film, increasing the number of sites where corrosion can be initiated and rendering the composite liable to severe attack. Thus, this research work was performed to investigate if a suitable concentration of lanthanide salts (LaCl3 and CeCl3) could be identified that could improve both uniform and pitting corrosion resistance.
Originality/value
Earlier studies on the corrosion inhibition of 6061‐SiC used cerium conversion coatings. More recently (i.e. during the last 1‐2 years) work has started on lanthanum conversion coating on Al alloys. However, little work has been carried out on use of these lanthanide salts (CeCl3 and LaCl3) as corrosion inhibitors for 6061‐SiC. The present research work was performed in order to better understand the effectiveness of these inhibitors to reduce corrosion attack on 6061‐8(vol.%) SiC.
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Zeinab Abdel Hamid, H.B. Hassan and Mohamed Sultan
The improvement of the hydrogen evolution reaction (HER) performance requires more efficient and inexpensive electrocatalysts. The purpose of this study is to prepare Ni-W and…
Abstract
Purpose
The improvement of the hydrogen evolution reaction (HER) performance requires more efficient and inexpensive electrocatalysts. The purpose of this study is to prepare Ni-W and Ni-W-P thin films using the electrodeposition technique using a pulse current and investigate their behaviors toward HER in an acidic solution.
Design/methodology/approach
The aim is to prepare Ni-W and Ni-W-P films by the electrodeposition technique using a pulse current and estimate their performance for the HER. The surface morphologies and chemical compositions of the deposited films were assessed using scanning electron microscopy, energy-dispersive X-ray analysis and X-ray diffraction. Linear sweep voltammetry, chronoamperometry, Tafel plots and electrochemical impedance spectroscopy were used to evaluate the prepared electrodes toward the hydrogen evolution process.
Findings
The main conclusion is that the surface morphology of Ni–W deposited film is a crystalline structure, while that of Ni-W-P deposit is an amorphous structure. HER activity on Ni-W electrodes increases with decreasing the Wt.% of W to 7.83 Wt.% in the prepared electrodes. In addition, the presence of P enhances HER activity, which increases with increasing the Wt.% of P in the prepared Ni-W-P electrodes. Both Ni-W (7.83 Wt.% W) and Ni-W-P (20.34 Wt.% P), which have been prepared at 8 A dm−2 display the best performance toward HER compared to the other prepared electrodes. They exhibit high catalytic activities toward HER, which is evidenced by high hydrogen evolution current density values of 9.52 and 33.98 mA cm−2, low onset potentials of −0.73 and −0.63 V, low Tafel slopes of −125 mV/dec, high exchange current densities of 0.058 and 0.20 mA cm−2, low charge transfer resistances (Rct) of 226.28 and 75.8 ohm·cm2 for Ni-W (7.83 Wt.% W) and Ni-W-P (20.34 Wt.% P), respectively; moreover, they exhibited considerable stabilities too.
Originality/value
The results presented in this work are an insight into understanding the performance of the prepared Cu electrodes coated by Ni-W and Ni-W-P films toward HER. In this work, a consistent assessment of the results achieved on laboratory scale has been conducted.
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Manawwer Alam and Naser M. Alandis
The purpose of this investigation was to develop sustainable resource-based anticorrosive coating material using Pongamia glabra seed oil and tannic acid (TA), as well as to…
Abstract
Purpose
The purpose of this investigation was to develop sustainable resource-based anticorrosive coating material using Pongamia glabra seed oil and tannic acid (TA), as well as to improve the coating properties.
Design/methodology/approach
TA-modified fatty amide diol was synthesized by condensation polymerization. First, Pongamia glabra seed oil was converted to fatty amide diol (Pongamia oil fatty amide, PFA) that was further modified by TA with different parts per hundred of resin (10, 15 and 20) to develop a polyether fatty amide (PFA-TA). The confirmation of reaction between TA and PFA was carried out using Fourier transform infrared spectroscopy. The thermal behavior of PFA-TA was studied by thermogravimetric analyses. Coatings of several PFA-TA resins were applied to steel (i.e. plain carbon steel) coupons to investigate their physico-mechanical and anticorrosive performance. The corrosion protection performance was observed using AC impedance and polarization tests.
Findings
TA-modified fatty amide coatings showed the highest scratch hardness of 2.5 kg, flexibility (1/8 inch) and gloss at 45° was 60-62. Among all compositions, PFA-TA15 showed the best physico-mechanical and anticorrosion performance. Corrosion tests of coated panels were examined in different corrosive media (3.5 wt per cent HCl, 3.5 wt per cent NaOH and 5.0 wt per cent NaCl) using potentiodynamic polarization and AC impedance measurements. PFA-TA may find application as an eco-friendly protective coating, and thermal analyses revealed that it can be safely used up to 300°C.
Originality/value
This paper provides the development of protective coatings for steel from non-edible seed oil and TA to utilize sustainable resources.