Corrosion Kinetic Parameters Research Articles

Investigation of Alumina-Doped Prunus domestica Gum Grafted Polyaniline Epoxy Resin for Corrosion Protection Coatings for Mild Steel and Stainless Steel.

Eco-friendly inhibitors have attracted considerable interest due to the increasing environmental issues caused by the extensive use of hazardous corrosion inhibitors. In this paper, environmentally friendly PDG-g-PANI/Al2O3 composites were prepared by a low-cost inverse emulsion polymerization for corrosion inhibition of mild steel (MS) and stainless steel (SS). The PDG-g-PANI/Al2O3 composites were characterized by different techniques such as X-ray diffraction (XRD), UV/Vis, and FTIR spectroscopy. XRD measurements show that the PDG-g-PANI/Al2O3 composite is mostly amorphous and scanning electron micrographs (SEM) reveal a uniform distribution of Al2O3 on the surface of the PDG-g-PANI matrix. The composite was applied as a corrosion inhibitor on mild steel (MS) and stainless steel (SS), and its efficiency was investigated by potentiodynamic polarization measurement in a 3.5% NaCl and 1 M H2SO4 solution. Corrosion kinetic parameters obtained from Tafel evaluation show that the PDG-g-PANI/Al2O3 composites protect the surface of MS and SS with inhibition efficiencies of 92.3% and 51.9% in 3.5% NaCl solution, which is notably higher than those obtained with untreated epoxy resin (89.3% and 99.5%). In particular, the mixture of epoxy/PDG-g-PANI/Al2O3 shows the best performance with an inhibition efficiency up to 99.9% on MS and SS. An equivalent good inhibition efficiency was obtained for the composite for 1M H2SO4. Analysis of activation energy, formation enthalpy, and entropy values suggest that the epoxy/PDG-g-PANI/Al2O3 coating is thermodynamically favorable for corrosion protection of MS and exhibits long-lasting stability.

Improved Corrosion Resistance, Mechanical Stability and Biocompatibility of Functionalized Multiwall Carbon Nanotube Incorporated Calcium-Deficient Apatite for Orthopedic and Dental Applications

This report describes the successful development of functionalized multiwall carbon nanotube (MWCNT) incorporated β-tricalcium phosphate (β-TCP) by typical physical method and its coatings on medical grade 316L SS (316L Stainless Steel) substrate for orthopedic and dental applications. The synthesized material was confirmed by physical and analytical techniques. The improved adhesion property was clearly shown in the field emission scanning electron microscopy (FESEM) cross-sectional view. The Brunauer–Emmett–Teller (BET) analysis reveals the intact nature of the coating on the metal surface with reduced pore size which drastically improves the protective nature of the coating in the aggressive physiological environment the obtained corrosion kinetic parameters also support the observation. The results obtained from the hardness tests and thermogravimetric analysis revealed the information about the mechanical stability (7.1 GPa) and thermal stability of the developed materials. The apatite formation ability tested in the simulated body fluid demonstrates that the developed materials are potential enough to use it as a biomaterial to correct and repair the hard tissue defects.Graphical Abstract

Research on corrosion mechanism of microstructure on low alloy steel in humid atmosphere

The corrosion process of low-alloy steels with three different microstructures in a humid atmosphere was systematically studied in this paper. Scanning electron microscope (SEM), transmission electron microscope (TEM), scanning Kelvin probe force microscope (SKPFM) and electrochemical measurement were conducted to characterize the microstructure, surface Volta potential and corrosion kinetic parameters of different phase. Confocal laser scanning microscope (CLSM) and X-ray diffraction (XRD) were utilized to characterize morphology and composition of rust layer. The results show that the volt potential of the substrate surface has a linear relationship with the corrosion kinetic parameters, and the structure with small micro-area potential difference and low average potential has better corrosion resistance. The ferrite in the dual phase will preferentially dissolve as an anode to form a crater, which will be filled with corrosion products, resulting in an uneven diffusion of oxygen and thus the formation of a concentration polarization. Dual phase steel will form a poorly protective rust layer, which causing the corrosion resistance analysis to be inconsistent with the final corrosion rate results.

Simulated microbial corrosion in oil, gas and non-volcanic geothermal energy installations: The role of biofilm on pipeline corrosion

The role of biofilm in the Microbiologically Influenced Corrosion (MIC) of carbon steel by Sulfate Reducing Bacteria (SRB) in oil and gas exploitation, and geothermal installations is investigated. Simulated biofilm made of calcium alginate, abiotic sulfide (to mimic SRB metabolic end product H2S), CO2 (to mimic CO2 from SRB dissimilatory sulfate reduction) and simulated brine (3.0 wt% NaCl) are used to simulate the SRB environment. For reference experiments, distilled water is used instead of simulated brine. The electrochemical results show that the simulated biofilm in the reference at 120 min exposure time and in brine experiments neither inhibits nor accelerates corrosion. These results are strongly supported by corrosion kinetic adsorption parameters, statistical T-test, ICP-OES, pH, SEM-EDS and XRD. The results contradict with the existing literature on the role of biofilm and this is likely due to the presence of both H2S and CO2 as simulated SRB metabolites. Despite of this discrepancy, the obtained corrosion rates (0.25 to 1.6 mm/year) in the simulated SRB environment are comparable to published corrosion rates obtained in SRB experiments (0.20 to 1.2 mm/year). The results highlight the novelty of this research and have a direct impact on the role of other microbial metabolites on the corrosion of carbon steel.

Combining Experimental and Quantum Chemical Study of 2-(5-Nitro-1,3-Dihydro Benzimidazol-2-Ylidene)-3-Oxo-3-(2-Oxo-2H-Chromen-3-yl) Propanenitrile as Copper Corrosion Inhibitor in Nitric Acid Solution

Due to acidic solutions aggressiveness, corrosion inhibitors use is considered to be one the most practical methods to delay metals dissolution in the said solutions. In this study benzimidazolyl derivative namely 2-cyanochalcones 2-(5-nitro-1,3-dihydrobenzimidazol-2-ylidene)-3-oxo-3-(2-oxo-2H-chromen-3-yl) propanenitrile which was synthesized was then applied as a corrosion inhibitor for copper in 1 M HNO3 solution. The inhibition action of this molecule was evaluated by gravimetric and density functional theory (DFT) methods. It was found experimentally that this compound has a better inhibition performance and its adsorption on copper surface follows Langmuir adsorption isotherm. This adsorption evolves with temperature and inhibitor concentration, it is endothermic and occurs spontaneously with an increase in disorder. Corrosion kinetic parameters analysis supported by Adejo-Ekwenchi model revealed the existence of both physisorption and chemisorption. DFT calculations related that compound adsorption on copper surface is due to its electron donating and accepting capacity. The reactive regions specifying the electrophilic and nucleophilic attack sites were analyzed using Fukui and dual descriptor functions. Experimental results obtained were compared with the theoretical findings.

Strong and ductile Fe-24Mn-3Cr alloy resistant against erosion-corrosion

The ternary-based Fe-24Mn-3Cr alloy has superior mechanical properties based on an attractive combination of high strength and ductility, with long-term environmental stability in highly corrosive environments compared to conventional ferritic steel alloys. This study reports that the environmental instability caused by the rapid electrochemical corrosion kinetics on the surface of conventional high Mn-bearing ferrous alloys could be overcome by a combination of high Mn–low Cr-balanced Fe and their synergistic interactions. In contrast to Cr-free Mn-bearing alloys, the high Mn–low Cr-bearing alloy showed comparatively lower corrosion kinetic parameters, without a continuously increasing trend, and higher polarization resistance according to electrochemical polarization and impedance spectroscopy measurements. Moreover, the rate of degradation caused by erosion–corrosion synergistic interaction under erosion–corrosion dynamic flow conditions was the lowest in the high Mn–low Cr-bearing alloy. These surface-inhibiting characteristics of the alloy were attributed primarily to the formation of a bilayer scale structure consisting of inner α-Fe2−xCrxO3/outer FexMn3−xO4 on the surface.

Tribocorrosion Behaviour of Biomedical Porous Ti–20Nb–5Ag Alloy in Simulated Body Fluid

Porous Ti–20Nb–5Ag (wt.%) alloy was developed using powder metallurgy (PM) route with the porosity of 43% after sintering in a high vacuum atmosphere. The microstructure of the porous alloy revealed various micro, macro and interconnected pores with an average pore size of about 114 µm. Tribocorrosion behaviour of the porous alloy was examined in simulated body fluid under the various applied load of 1–10 N using DC electrochemical corrosion technique and kinetic parameters (corrosion potential, corrosion current density and breakdown potentials). After tribocorrosion test, the OCP values decreased from 0.17 to − 0.49 VSCE as applied load was increased. The potentiodynamic polarization results revealed that the corrosion potential decreased, while corrosion current density increased under higher applied loads. Active–passive transition plots showed metastable passivity due to severe fluctuations of passive current density. After tribocorrosion, the surface morphology was analysed using SEM, and it exhibited the severity of wear tracks at higher applied loads. The results indicated that the developed porous Ti–20Nb–5Ag alloys exhibit better tribocorrosion properties in simulated body fluid. Through observations of SEM images of the worn surfaces, the visible scratches and deep grooves were observed along the sliding direction, indicating a predominant abrasive mechanism.

Novel Green Corrosion Protection for Mild Steel on Optimal Temperature and Pressure

The green novel catalyst 1-[(4-nitrophenyl) methyl]-4-(pyridin-2-yl)piperazine (NMPP) polymer composite was synthesized by condensation polymerization. The polymer composite was characterized by Fourier transform infrared (FTIR), and high resolution scanning electron microscope (HR-SEM). The inhibition action of the polymer composite was investigated by conventional weight loss method, and electrochemical impedance spectroscopy (EIS). The maximum corrosion inhibition efficiency of 88.34% was obtained at concentration level of 6% at 303 K. The results revealed NMPP as a mixed type corrosion inhibitor, the thermodynamic and kinetic parameters also revealed adsorption of catalyst on to mild surface as exothermic and the adsorption was confirmed by conventional weight loss method. The morphology of mild steel coupons was investigated by HR-SEM. The HR-SEM results showed novel catalyst to have inhibited corrosion on mild steel in 1 M HCL on CO2 environment.

Kinetic and thermodynamic analyses of the corrosion inhibition of synthetic extracellular polymeric substances

Background Extracellular polymeric substances (EPS) extracted from waste activated sludge (WAS) have previously shown its potential in corrosion inhibition. The aim of this study is to design a synthetic EPS formulation as a surrogate of natural WAS EPS to overcome the corrosion inhibition inconsistency in WAS EPS. The adsorption behavior of the designed inhibitor was studied by kinetic and thermodynamic analyses. Methods Synthetic EPS is a bio-inspired material that was formulated based on the most typical chemical compositions of natural WAS EPS, that is, proteins, carbohydrates, humic substances, nucleic acids, and uronic acids, which was not optimized for corrosion inhibition performance. It is a mixture of glutamic acid, carboxymethylcellulose, humic acid, thymine, and alginic acid. Its corrosion inhibition performance was tested with carbon steel in 3.64% NaCl saturated with CO2, using the potentiodynamic polarization scanning technique. The resulted electrochemical parameters were used to evaluate the empirical corrosion kinetic and thermodynamic adsorption parameters. Results Addition of synthetic EPS showed significant decrease in corrosion rate as compared to the control. The inhibition efficiency improved with increasing inhibitor concentration and temperature. The optimum performance was 94% with 204 mg/L of inhibitor applied at 70 °C (343 K). The inhibition performance was controlled by both the concentration of inhibitor and temperature. Chemisorption of the inhibitor molecules contributed to the overall inhibition performance, reducing the contact of metal with the corrosive environment, thus, slowing down the overall corrosion rate.

Effect of akyl chain length, flow, and temperature on the corrosion inhibition of carbon steel in a simulated acidizing environment by an imidazoline-based inhibitor

An imidazoline, 2-heptadecyl-1-[2-(octadecanoylamino)ethyl]-2- imidazoline (QSI) with -C17H35 as the tail chain length was synthesized, characterized, and studied as corrosion inhibitor for low carbon steel in 15% HCl solution under static and hydrodynamic conditions. Influence of addition of KI, temperature, and chain length of pendant hydrocarbon on inhibition efficiency (η) was also examined. It is found that, QSI exhibits a mixed type behavior but fairly inhibited the corrosion of low carbon steel in the studied medium. The maximum concentration studied (400 mg/L) afforded η of <50%. Addition of KI to QSI synergistically enhanced the corrosion inhibition performance of QSI, upgrading the η to approximately 90%. Increase in the system temperature increases the η of both QSI and QSI + KI. From the variation of η with temperature and the calculated corrosion kinetic parameters, chemical adsorption is proposed as the adsorption mechanism of the additives. QSI performs better under hydrodynamic condition than static condition. However, the corrosion resistance of the metal decreases at rotation speed higher than 1000 rpm. Inhibition efficiency of imidazoline decreases as the length of the hydrocarbon pendant chain increases. Imidazoline compounds with -C13H27 and -C15H31 as the length of the pendant group hydrocarbon perform better than QSI with -C17H35.

Thermodynamic and Electrochemical Analysis of Synergistic Corrosion Inhibition Performance of Natural Polysaccharides with Metal Halides on Mild Steel in Hydrochloric Acid Solution

The effect of synergistic corrosion inhibition efficiency of Azadirachta indica gum with halides (KCl, KBr and KI) on mild steel in 1 mol L−1 HCl was studied using conventional weight loss and electrochemical studies. The temperature (303–328 ± 1 K) and time (1, 2, 3, 4, 6 and 24 h) effect on the inhibition of corrosion has also been tested. The inhibition efficiency of gum exudates of Azadirachta indica considerably increased with the presence of halide ions at all temperature ranges studied. Corrosion kinetic parameters and thermodynamic adsorption parameters were calculated and discussed in detail. The mode of adsorption of inhibitor on the mild steel surface was examined by FT-IR spectroscopy.

Theoretical and experimental studies of a new aniline derivative corrosion inhibitor for mild steel in acid medium

Abstract4‐Chloro‐N‐(pyridin‐2‐ylmethyl)aniline (CPYA) was synthesized by a simple and inexpensive method and tested as a corrosion inhibitor in acid medium for mild steel by using gravimetric studies and electrochemical measurements. An average maximum efficiency of 96.0% was achieved at 4.59 mmol/L. Corrosion kinetic and thermodynamic parameters were also analyzed. Surface analyses (atomic force microscopy and scanning electron microscopy) show that protection is enabled by adsorption on the metal, forming a film. Quantum chemical calculations were performed to access information regarding the molecular structure in the corrosive medium and to support interpretation of the results obtained by experimental methods.

Study the Effect of Cyperus Rotundus Extracted as Mouthwash on the Corrosion of Dental Amalgam

Many extracted material were used as mouthwash to settle different kinds of oral fungi and bacteria. In this study an extractive of Cyperus rotundus plant E.C.R. which is very active as a mouthwash, was used in concentration range (10-25) ppm in artificial saliva at pH=6.4 and temperature range (288-318) K, to study it’s inhibitory effect on the corrosion of dental amalgam. Potentiostatic and cyclic polarization were used to follow this study. The presence of E.C.R. lead to shift the corrosion potential to the active direction and decreased the corrosion rate to about 98.87%, the inhibition action of E.C.R. resulting from the adsorption of C.R.E. layer between amalgam and saliva as FTIR spectrums shows, where the variety of FTIR adsorption of many group were noticed for the free E.C.R. and adsorbed E.C.R. layer. Thermodynamic of adsorption, corrosion kinetic parameters were also investigated.

Electrochemical Behavior of a Nanostructured La1.25Gd0.25Mg0.5Ni7 Hydrogen Storage Material Modified with Magnetron Sputtered Nickel

A nanocrystalline La1.25Gd0.25Mg0.5Ni7 hydrogen storage material with a dominant A2B7 phase was obtained by mechanical alloying (MA) and heat-treatment (1123 K for 0.5 h). The concentration of the AB5 phase is 6.4 at.% and is marginally lower than that in the Gd-free parent La1.5Mg0.5Ni7 alloy. The powder fraction of 20–50 μm was encapsulated with thin (0.31 μm thick), amorphous nickel using magnetron sputtering. Electrochemical multicycling allowed the determination of the corrosion kinetic parameters, as well as the exchange current density of a H2O/H2 system and the effective diffusivity of hydrogen. Partial substitution of Gd for La in the La1.5Mg0.5Ni7 nanocrystalline parent alloy increases the electrode discharge capacity (up to 16%) but somewhat deteriorates its activation properties. Gd addition does not affect the corrosion degradation resistance, although the corrosion properties are weakened after particle encapsulation with the amorphous nickel coating. Finally, in spite of the Gd-modified La1.5Mg0.5Ni7 nanocrystalline alloy revealing a 10% lower exchange current density of the H2O/H2 system compared to the parent alloy, this property can be considerably improved (by >50%) by Ni particle encapsulation. The hydrogen diffusivity of the Gd-modified material is faster compared to the parent material but is slowed down by the Ni coating.

Corrosion inhibition of N80 steel in 10% HCl + 8% HBF4 solution

PurposeThis paper aims to analyze the corrosion and corrosion inhibition of N80 in 10 per cent HCl + 8 per cent fluoroboric acid (HBF4) solution for acidizing operation.Design/methodology/approachThe corrosion rate, kinetic parameters (Ea, A) and thermodynamic parameters (ΔH, ΔS) of N80 steel in fresh acid and spent acid, 10 per cent HCl + 8 per cent HBF4, 10 per cent HCl and 8 per cent HBF4 solutions were calculated through immersion tests. The corrosion and inhibition properties were studied through X-ray diffraction and electrochemical measurements. The corrosion morphology of the corrosion product was examined by scanning electron microscopy (SEM).FindingsThe results demonstrated that the spent acid was the main cause of acidification corrosion, and the HBF4 would cause serious corrosion to N80 steel. The results showed that the N80 steel was more seriously corroded in the spent acid than in fresh acid, and the hydrolysis of HBF4 accelerates the dissolution process of N80 steel anode to control the corrosion reaction. The results showed that the acidification will definitely cause serious corrosion to the oil tube; therefore, necessary anti-corrosion measures must be taken in the acidification process.Originality/valueThe results showed that acidizing the formation with 10 per cent HCl + 8 per cent HBF4 will definitely cause serious corrosion to the oil tube, especially when the spent acid flows back. Therefore, necessary anti-corrosion measures must be taken in the acidification process, especially in the spent acid flowback stage.

Atmospheric corrosion patterns of electrogalvanized mild steel at east southern coastal areas of CPEC

The primary goal of the study was to establish corrosivity category in accordance with ISO 9223 norm of the two test stations located at National Institute of Oceanography (NIO) and Karachi Port Trust (KPT) along the east southern coastal route of China Pakistan Economic Corridor (CPEC) project in Pakistan. Electrogalvanized mild steel test coupons were exposed for a period of 12 months from May 2014 to May 2015. Results indicated that for both NIO and KPT test stations the corrosivity category in term of corrosion rate (C5+) was not in agreement with the corrosivity category (C5) established by using the pollution category and time of wetness. Corrosion kinetic parameters n and correlation coefficient (R2) obtained for NIO were 1.58 and 0.98 and for KPT 1.43 and 0.95 respectively. Scanning electron microscopy/energy dispersive X‐ray spectroscopy (SEM/EDS) showed the presence of simonkolleite at NIO while zincite and hydrozincite at KPT. Fourier transform infrared (FTIR) spectroscopy showed that the typical corrosion products formed on both test stations were simonkolleite and hydrozincite. XRD showed the presence of zincite at both test stations and hydrozincite only at KPT.

A comparative study on corrosion kinetic parameter estimation methods for the early stage corrosion of Q345B steel in 3.5wt% NaCl solution

Corrosion kinetic parameters play an important role in researchers’ ability to understand and predict corrosion behavior. The corrosion kinetic parameters of structural steel Q345B specimens immersed in 3.5wt% NaCl solution for 1–2 h were determined using linear polarization resistance (LPR), Tafel-curve multiparameter fitting, electrochemical impedance spectroscopy (EIS), and electrochemical frequency modulation (EFM) methods. The advantages and disadvantages of each method were investigated and discussed through comparative investigation. Meanwhile, the average corrosion rate was examined using traditional coupon tests. The results showed that the corrosion current density values estimated by EFM at a base frequency of 0.001 Hz and those obtained by Tafel-curve four-parameter fitting (TC4) are similar and consistent with the results of coupon tests. Because of their slight perturbation of the corrosion system, EIS and EFM/TC4 in collaborative application are the recommended techniques for determining the kinetics and the corresponding parameters for the homogeneous corrosion of the naked metal. In our study of the electrochemical kinetics, we obtained much more abundant and accurate electrochemical kinetic parameters through the combined use of different electrochemical methods.

Aster koraiensis as nontoxic corrosion inhibitor for mild steel in sulfuric acid

Abstract Inhibition efficiency of Aster koraiensis leaf extract toward corrosion of mild steel in 1 M H2SO4 solution was investigated using weight loss, electrochemical, FT-IR, SEM, and EDX methods The individual phenolic compounds present in A. koraiensis extract were identified. Maximum efficiency of 90.53% was achieved at 2000 ppm of the extract. The corrosion kinetic parameters determined from the polarization curves indicated that the extract acted as a mixed-type inhibitor. Adsorption of the inhibitor on the mild steel surface obeyed the Langmuir isotherm. SEM investigations confirmed the formation of inhibition layer unto the metal surface by compounds present in the extract.

Effect of Stress Ratio and Loading Frequency on the Corrosion Fatigue Behavior of Smooth Steel Wire in Different Solutions.

In this work, the effects of loading condition and corrosion solution on the corrosion fatigue behavior of smooth steel wire were discussed. The results of polarization curves and weight loss curves showed that the corrosion of steel wire in acid solution was more severe than that in neutral and alkaline solutions. With the extension of immersion time in acid solution, the cathodic reaction of steel wire gradually changed from the reduction of hydrogen ion to the reduction of oxygen, but was always the reduction of hydrogen ion in neutral and alkaline solutions. The corrosion kinetic parameters and equivalent circuits of steel wires were also obtained by simulating the Nyquist diagrams. In corrosion fatigue test, the effect of stress ratio and loading frequency on the crack initiation mechanism was emphasized. The strong corrosivity of acid solution could accelerate the nucleation of crack tip. The initiation mechanism of crack under different conditions was summarized according to the side and fracture surface morphologies. For the crack initiation mechanism of anodic dissolution, the stronger the corrosivity of solution was, the more easily the fatigue crack source formed, while, for the crack initiation mechanism of deformation activation, the lower stress ratio and higher frequency would accelerate the generation of corrosion fatigue crack source.

Corrosion Resistance of the Joint of Stainless Steels in Aggressive Solution

The CO2 laser welding technique was proposed as a method of joining dissimilar materials. The corrosion resistance of the joint of TP347HFG and VM12-SHC stainless steels in chloride solution was investigated. The stainless steels were butt welded. The materials were examined by electrochemical methods. The microstructure of the weld and the heat-affected zones were observed in an optical (OM) and scanning electron microscope (SEM). The X-ray fluorescence spectrometer (XRF) was used to determine variations in the main chemical elements across the fillet weld. The results showed a substantial intermixing of both substrates within the fusion zone. The joint in the environment of strong electrolytes of Cl- corrodes according to the electrochemical mechanism. The corrosion kinetic parameters for the substrates were calculated and discussed. The joint possesses medium resistance to electrochemical corrosion in relation to both steels. Keywords: Austenitic, corrosion kinetic parameters, cross-section, electrochemical corrosion, laser welding, joint, martensitic.