Tafel Extrapolation Research Articles

The effect of scan rate on the precision of determining corrosion current by Tafel extrapolation: A numerical study on the example of pure Cu in chloride containing medium

Although potentiodynamic polarization is a common technique for determining corrosion current, there is no consensus on the choice of scanning parameters. This study explores a 1D mathematical model of copper under oxygen reduction in a chloride containing medium to quantify the effects of scan rate, starting overpotential, and scan direction on the features of polarization curve. All the relevant tendencies of the cathodic branch are reproduced experimentally and explained by local oxygen consumption and coverage by CuCl. The corresponding effects on the precision of determining corrosion current are discussed, revealing that the largest deviation of up to 50% is obtained for the slowest scan rate and largest starting overpotential.

EFFECT OF AL2O3 NANOPARTICLES ON CORROSION BEHAVIOR OF ALUIMNUM ALLOY (AL-4.5 WT% CU-1.5 WT% MG) FABRICATED BY POWDER METALLURGY

In this research the effect of Al2O3 nanoparticles on corrosion behavior of aluminum base alloy (Al-4.5 wt% Cu-1.5 wt% Mg) has been investigated. Nanocomopsites reinforced with variable contents of 1, 3 and 5 wt% of Al2O3 nanoparticles were fabricated using powder metallurgy. All samples were prepared from the base alloy powders under the best powder metallurgy processing conditions of 6 hr of mixing time, 450 MPa of compaction pressure and 560 °C of sintering temperature. Density and micro hardness measurements, and electrochemical corrosion tests are performed for all prepared samples in 3.5 wt% NaCl solution at room temperature using potentiostate instrument. It has been found that density and micro hardness of the nanocomposite increase with increasing of wt% Al2O3 nanoparticles to Al matrix. It was found from Tafel extrapolation method that corrosion rates of the nanocomposites reinforced with alumina nanoparticles were lower than that of base alloy. From results of corrosion test by potentiodynamic cyclic polarization method, it was found the pitting corrosion resistance improves with adding of Al2O3 nanoparticles. It was noticed that the pits disappear and the hysteresis loop disappears also from anodic polarization curve.

Cold Metal Transfer Welding of AA6061 to AA7075: Mechanical Properties and Corrosion

Cold metal transfer (CMT) welding provides many advantages for welding of dissimilar materials and thin sheets with its superior heat input control mechanism. In this study, AA6061 and AA7075 aluminum alloys were joined with CMT welding. The effect of welding parameters on hardness, tensile strength, and corrosion rate was investigated. The Tafel extrapolation method was carried out to determine the corrosion rates of AA6061 and AA7075 base metals and AA6061–AA7075 joints. Increasing heat input was found to be detrimental for both mechanical properties and corrosion resistance. The outcomes showed that CMT welding produces adequate joints of AA6061–AA7075 in terms of mechanical properties and corrosion resistance, favorably with welding parameters that provide low heat input.

Effect of Quenching and Tempering Temperature on Corrosion Behavior of Boron Steels in 3.5 wt.% NaCl Solution

This study was carried out to examine the impact of austenitization and tempering temperatures on the corrosion characteristics of boron steels. Boron steel samples were austenitized at 850 °C, 900 °C, and 950 °C, and then quenched in environmental water. After quenching, the samples were tempered at 150 °C, 300 °C, and 450 °C for 30 minutes to prepare specimens. The corrosion characteristics of quenched and tempered boron steels in a 3.5 wt.% NaCl solution were examined using Tafel extrapolation method. Significant statistical differences have been observed between the tested boron steels in terms of corrosion rate. Changing C concentration affected the corrosion rates of boron steels after their immersion into a 3.5 wt% NaCl solution and increasing C content generally accelerated the corrosion rate. A poor correlation has been found between average ferrite grain size and corrosion rate under the examined heat treatment conditions for tested boron steels.

Effect of Heat Treatment on Properties of Titanium Biomedical Alloy

The aim of this work to study the effects of heat treatments on the alloy (Ti6Al4V) which produced by powder metallurgy methods and consists of a mixture of the following powders (titanium 90%, aluminum 6% and vanadium 4%).The heat treatments (sintering process) take place in different time of stay. The alloy (Ti6Al4V) used as biomaterials in the medical field due to their excellent properties such as : high corrosion resistance, high wear resistance, high breaking strength, higher ductility, non-toxic and non-magnetic, suitable elasticity coefficient, where used as an alternative to replacing damaged hard tissues such as orthopaedic, osteosynthesis, full hip joint, knee joint and dental implants. The elements were weighed by a highly sensitive electronic balance, the powder was mixed for five hours, Then press with a pressure (700 MPa) to transition to green cylindrical samples with a diameter of 13 mm. The sintering process was carried out at 1100 °C. The porosity of the samples decreases at high temperatures and time of stay to a certain extent and then increase porosity at very high temperatures due to the growth of particle and the expansion of gases. The density of the samples after the sintering process increases with increasing the temperature because increase the mass diffusion of particles and reduces porosities that increase contact points between particles. The sintering processes lead to increase the hardness, where the hardness was tested in the Vickers hardness method. The wear increased by increasing (load, time and sliding distance), and increase the hardness leads to a low volume loss (the amount of metal lost a few) as the relationship between them is inverse. To study the corrosion behavior of the samples that have been sintering processes under different time of stay and to perform this test (tafel Extrapolation test) in 0.9 NaCl solution, where the sample is subjected to high temperature and a long period of stay and therefore This lead to increases the diffusion and increases the contact points between the particles and increase the forces of bonds between the particles and this leads to increased corrosion current and therefore the oxidation process to be a high degree and this leads to the higher rate of corrosion.

Corrosion behaviour of Al 7075 /TiC composites processed through friction stir processing

Aluminum alloys are promising for structural applications due to their high strength-to-weight ratio, resistance to corrosion and light weight. Aluminum/aluminum alloy matrix composites reinforced with particles like ceramic possess higher strength and hardness. Aluminum alloy 7075-T651 of 6.35 mm thick plate was used as a base material for the present study and surface modification was done using friction stir processing (FSP). H13 tool steel in the heat-treated condition was used as the tool material. TiC particle of 3.5µm size was used as a reinforcement in different volume fractions 2, 4 and 6 vol.% respectively. FSP process was carried out at travel speed of 30 mm/min and a rotational speed of 1200 rpm. Corrosion studies were carried out using 3.5% NaCl with varying the molarity of the electrolyte (1M, 2M, and 3M NaCl). Corrosion rates were calculated from corrosion current density (Icorr), by using polarization techniques with the help of Tafel extrapolation. The effect of TiC on microstructural development, hardness and corrosion behaviour was studied. It was observed that the corrosion resistance of the Al 7075-TiC composite was higher than the Al 7075-T651. The corroded surface morphology of revealed pits on the surface and the number of pits increased with increasing the concentration of NaCl..

Corrosion of Platinum Nanocoatings Thin Films Deposited by Sputtering Deposition Method for Medical Applications

Platinum (Pt.) thin films have been deposited by Magnetron Sputtering Deposition method with 25 nm and 50 nm thickness by used power RF for deposited 5 nm Titanium (Ti) firstly then used DC for deposited Platinum (Pt) on Ni-Cr alloy substrate. SEM/EDX and Ellipsometry Spectroscopy have been used to investigate the morphology, element analysis, nanothickness and roughness of the thin films respectively. Electrochemical corrosion tests have been used to analyze the localized corrosion resistance by used cyclic polarization, Tafel extrapolation and open circuit potential (o.c.p) methods on artificial saliva solution at 37 ±1 oC. The results show the ability to deposit 5 nm of Ti before deposited of Pt. film to improve the adhesive of the films, nanostructure morphology of the Pt. film without defect or microcracks, nanocoatings thickness of Pt. film, and high localized corrosion resistance in artificial saliva corrosive media.

Effect of Dissolved Oxygen on the Corrosion Rate of Stainless Steel in a Sodium Chloride Solution

The corrosion currents of 17-4РН stainless steel in an NaCl solution at various contents of dissolved oxygen are obtained by the method of Tafel extrapolation. It is shown that the dependences of the corrosion current on the concentration of dissolved oxygen are significantly different on the passive and cathodically activated specimens; however, they are similar after preliminary cathodic activation and after the anodic activation with chloride ions.

Synthesis and characterization of kaolinite/polyaniline nanocomposites and investigating their anticorrosive performance in chlorinated rubber/alkyd coatings

Kaolinite/polyaniline nanocomposites (KPAns) were prepared byin situchemical oxidative polymerization. The nanocomposites were synthesized with four different aniline to kaolinite weight percentage; 5, 10, 15, and 20% to produce KPAn5, KPAn10, KPAn15, and KPAn20, respectively. The structural, morphological and thermal properties of the nanocomposites were characterized using Fourier transform infrared, X‐ray diffraction, scanning electron microscope (SEM)–energy dispersive X‐ray analyzer, transmission electron microscope, and Thermogravimetric analysis. The results revealed a very slight increase in the d‐spacing of kaolinite XRD peaks. SEM images showed hexagonal platy sheets of kaolinite crystals that are indistinguishable in KPAn nanocomposites images, especially on using a high amount of polyaniline (PANI). The increase in the percentage of carbon and nitrogen elements in EDAX data proved the adsorption of PANI on the surface of kaolinite platelets. To investigate the anticorrosive performance of the synthesized nanocomposites, kaolinite and KPAn nanocomposites were loaded in various amounts (1, 5, and 9%) in a blend of chlorinated rubber/medium oil alkyd resin (CR/MA) to prepare different formulations that were applied and evaluated as protective coats on steel substrates. Visual corrosion test revealed that 5% KPAn‐loaded CR/MA coats exhibited the best protection against corrosion amongst other formulations as indicated by their lowest degree of rusting and blistering. Potentiodynamic polarization measurements confirmed the highest protection of 5% KPAn10‐loaded CR/MA coat as indicated by the quantitative corrosion rates obtained from Tafel extrapolation. POLYM. COMPOS., 40:2777–2789, 2019. © 2018 Society of Plastics Engineers

Electrochemical Characterization of Az31 Magnesium Alloy Treated by Ultrasonic Impact Peening (Uip)

Electrochemical characteristics of AZ31 magnesium alloy after impacting by ultrasonic impact peening (UIP) were measured in order to evaluate its effect on corrosion resistance of mentioned alloy. For this purpose, potentio-dynamic polarization (PD) tests and electrochemical impedance spectroscopy (EIS) of ground and impacted samples were performed in 0.1 M NaCl solution at the temperature of 22±2 °C after 5 minutes of potential stabilization. The obtained PD curves were analysed using the Tafel extrapolation method and data from EIS measurements in form of Nyquist plots were quantified by the equivalent circuit method. The results showed clearly that application of the UIP significantly deteriorated corrosion resistance of AZ31 alloy in the chosen testing solution.

Corrosion Behaviours of Aged Haynes 282 and Inconel 718 in Acidic and Alkaline Environments

Haynes 282 and Inconel 718 are superalloy materials originally designed and used in aero- and land-based gas turbine engines. However, they are being considered and used in challenging environments such as nuclear power plants, chemical, and petrochemical plants due largely to their high creep strength and corrosion resistance at low and high temperatures. Recently, there is quest for their uses in the oil and gas refineries. This work examines the corrosion behaviour of these two materials in acidic and alkaline environments; similar to that in the petroleum refinery. The samples were cut, aged, and electrochemically characterized using VersaSTAT 3 model potentiostat with graphite counter electrode and Ag-AgCl SCE. The Linear polarization corrosion test conducted revealed that the corrosion rate, break down potential(Ecorr) and the corrosion current(Icorr) of the aged Haynes 218 are 0.05mmpy, 0.198V, 5.032µA in dilute HNO3 ; 0.145mmpy,16.23V,13.48 µA in dilute NaOH while those of aged Inconel 718 are 0.068mmpy,96.5V,63.56 µA in the dilute HNO3 and 0.026mmpy,0.41V,2.478 µA in the dilute NaOH respectively. These results showed that aged Haynes 282 has a higher corrosion resistance than aged Inconel 718 in the acidic medium ,but, the reverse in the alkaline medium .However better corrosion passivation was obtained in HNO3 for the two materials than in NaOH.Keywords- Superalloys, Haynes 282, Inconel 718, Tafel Extrapolation Method.

To Investigate the Effect of Heat Treatment on Low Carbon Steel Corrosion Behavior

This work was to investigating the corrosion behavior of low carbon steel in a salt solution of 3.5wt% NaCl after undergoing two different types of heat treatment at 960 ºC in a furnace. The material of low carbon steel was cut into nine small pieces under three groups A, B and C, without heated annealing and hardening heat treatment respectively. The heat treatment was at temperature 960ºC. The hardness of the sample as received will be 203 kg/mm2 while after hardening the hardness was increased. The sample was mounted using hot and cold mounting. The microstructure and surface morphology was observed by using Scanning Electron Microscope (SEM) and Optical Microscope (OM) after grinding, polishing and etching on the sample. In group A cementite can be observed clearly on pearlite on the surface before corrosion test. After four days soaking in 3.5 wt% NaCl solution was observed all cementite and pearlite will be transformed to austenite with the remnants of cementite make the surface unstable hence increases the initial corrosion. After four days soaking when the cementite is oxidized and a thick film of corrosion product covers the material surface. The formation of Martensite due to quenching and rapid cooling in group C sample increases the corrosion rate from 0.072 mpy to 0.302 due to decreased of corrosion potential from -572 mV to -639 mV after four days soaking. The corrosion rate of each sample was measured by using electrochemical polarization measurement and Tafel extrapolation technique. From previous result, it was observed that samples which had undergone annealing mode of heat treatment turned out to be the ones with the best corrosion resistance.

Nicotinic acid as green inhibitor for copper corrosion in 3.5 wt % NaCl solution: experimental and quantum chemical calculations

This work reports the inhibition properties of nicotinic acid (NAC) for copper protection during its applications in seawater systems such as water pipelines, shipbuilding, seawater desalination operations and heat exchange systems. The efficiency of nicotinic acid (NAC) as a copper corrosion inhibitor in 3.5 wt % NaCl solution was investigated by Tafel extrapolation and electrochemical impedance spectroscopy (EIS) methods in the temperature range from 20 to 50 °C. The corrosion parameters and the adsorption isotherms were determined from the potentiodynamic polarization curves. It was found that the inhibitory efficiency (η%) and the coverage rate (θ) increase to a maximum of 87.97 at 25 °C in 10 mM of nicotinic acid at fixed temperature but decrease as the temperature of the solution increases. Nicotinic acid acts is a purely cathodic inhibitor. Moreover, the obtained thermodynamic parameters using Langmuir model suggested a physical adsorption type. A correlation was found between the corrosion inhibition efficiency and the theoretical parameters obtained by the functional density method B3LYP/ 6-31 + G (d, p). All these results indicate that the addition of NAC in the corrosive solution significantly decreases the corrosion rate. Keywords : Nicotinic acid, copper corrosion inhibition, electrochemical impedance spectroscopy, quantum chemical calculations.

Retardation of Mild Steel Corrosion in Analogous Schiff Bases with Different Electronic Environments

Two Schiff bases namely (E)-2-((phenylimino)methyl) phenol (SA1) and (E)-2-methoxy-6-((phenylimino)methyl) phenol (SA2) were produced via reaction of phenylamine with 2-hydroxybenzaldehyde and 2-hydroxy-3-methoxybenzaldenyde, respectively. The structures were elucidated through spectral and physicochemical techniques of melting point, elemental analysis (C, H and N), 1H Nuclear Magnetic Resonance (NMR) and Infrared (IR) spectroscopy. The distinctive n(C=N) and d(OH) peaks for SA1 and SA2 appeared at 1615 and 1613 cm-1 and at 13.27 and 13.37 ppm, respectively. Electrodeposit both compounds on mild steel at 0.05 M concentration in 0.3 M NaOH was established through cyclic voltammetry (CV) and chronoamperometry (CA) methods. Yellow and brownish Schiff base layers were observed to be formed on the mild steel specimens. The coated and uncoated mild steel specimens were tested for their corrosion behavior using the Tafel Extrapolation Method (TEM) in 0.5 M NaCl. Results demonstrated that mild steel coated with SA2 through CA technique at potential +0.90 V showed the highest inhibition efficiency, hence indicating a superior surface coverage, with 97.20 % inhibition efficiency; while SA1 recorded the highest inhibition efficiency of 93.83 % at coating potential of +1.35 V.

Corrosion Progress Evaluation of a Rebar in Concrete by the Corrosion Monitoring Using the Tafel Extrapolation

Corrosion Progress Evaluation of a Rebar in Concrete by the Corrosion Monitoring Using the Tafel Extrapolation

Chryseobacterium indologenes MUT.2 bacterial biopolymer as a novel green inhibitor protecting carbon steel corrosion in acidic solution

Corrosion inhibition of Chryseobacterium Indologenes MUT.2 bacterial biopolymer was investigated in different biopolymer concentration (0.2–0.5 gl−1) as well as temperature ranging from 25 to 55 °C in 0.5 M HCl corrosive solution. Electrochemical studies were performed by Electrochemical Impedance Spectroscopy (EIS) and potentiodynamic polarization using Tafel extrapolation technique under different conditions. Results showed that increasing the biopolymer concentration enhanced the inhibition efficiency whereas increasing the temperature decreased the inhibition efficiency. Maximum inhibition efficiency of 58% was obtained in the presence of 0.5 gl−1 biopolymer at room temperature (25 °C). The biopolymer adsorption on metal surface obeyed Langmuir adsorption isotherm. Biopolymer acted as a mix inhibitor and physically adsorbed on metal surface. The biopolymer inhibitor deposition on metal surface has been indicated in Scanning Electron Microscope (SEM) images. Suitable mechanism was proposed for the inhibition process.

Quaternary aryl phosphonium salts as corrosion inhibitors for iron in HCl

Cathodic and anodic Tafel extrapolation data for the corrosion inhibition of iron in deaerated 1 M HCl at 22 °C are obtained for five synthesized phosphonium salts, 4-tolyltriphenyl-phosphonium chloride (TTPPC), 4-phenoltriphenylphosphonium chloride (PTPPC), 4-anilinetriphenylphosphonium bromide (ATPPB), 4-benzyl alcoholtriphenylphosphonium chloride (BATPPC), 4-hlorophenyltriphenylphosphonium bromide (CPTPPB), and two commercially available phosphonium salts, tetraphenylphosphonium bromide (TPPB) and methyltriphenylphosphonium bromide (MTPPB). The inhibitor concentrations ranged from 1 × 10−7 to 1 × 10−3 M. The inhibition of iron corrosion in 1 M HCl at 22 °C was found to be in the order TPPB > BATPPC > CPTPPB > PTPPC > MTPPB > TTPPC > ATPPB.

Effect of 1,2,3benzotriazole on the corrosion of aged 18Ni250 grade Maraging steel in Phosphoric acid solution

The 18 Ni 250 grade maraging steel is a potential high strength steel for advanced technologies such as aerospace, nuclear, and sporting goods. Phosphoric acid and Nitric acid solutions are used in pickling of delicate and precision items where re-rusting after pickling has to be avoided. The present work addresses the study of corrosion behaviour and inhibition using 1,2,3 benzotriazole of aged 18 Ni 250 grade maraging steel in phosphoric acid medium at higher concentration by Potentiodynamic Polarization Technique. The corrosion rates were determined in 1M, 1.5M and 2M by Tafel extrapolation technique in the temperature range 300C-500C with different concentrations of inhibitor. The results indicate that the corrosion rate increases with increase in acid concentration and temperature.Inhibition efficiency of 1,2,3benzotriazolewas found to increase with the increase in 1,2,3 benzotriazole concentration and decrease with the increase in temperature.The activation energy Ea and other thermodynamic parameters (ΔG˚,ΔH# andΔS#) have been evaluated and discussed. The standard free energy of adsorptionΔG˚ads values indicates that the adsorption is of mixed type. Scanning electron microscopy (SEM) study confirmed the formation of an adsorbed protective film on the metal surface.

Effects of ultrasonic agitation prior to deposition and additives in the bath on electrodeposited Ni-B/hBN composite coatings

Ni-B/hBN composite coatings were successfully deposited by conventional electroplating method on mild steel substrate. Electrodeposition was carried out in Watts type nickel electrolite and trimethylamine borane (TMAB) was used as boron element source. hBN particles with 1 μm average powder size were used as reinforcements. In this study, the effects of additives in the bath and ultrasonic mixing before deposition on the composite coating properties were evaluated. Crystal structure, morphology and composition of composite coatings were investigated by X-ray diffraction analysis, scanning electron microscopy and energy dispersive spectroscopy. Also corrosion behavior of composite coatings was analysed via Tafel extrapolation and open circuit potential techniques in 3.5% wt. NaCl solution. The results showed that the composite coatings that have compact and smooth properties were obtained and ultrasonic agitaiton significantly influenced corrosion resistance of composite coatings and uniform distribution of incorporated hBN particles. It was found that corrosion rate of the composite coatings was 76.7% and 78.5% lower than that of composite coatings produced in the bath without ultrasonic mixing and without ultrasonic mixing plus additives, respectively.

A comprehensive study on electrophoretic deposition of a novel type of collagen and hexagonal boron nitride reinforced hydroxyapatite/chitosan biocomposite coating

A novel family of Hydroxyapatite/Chitosan/Collagen/h-BN biocomposite coatings were successfully produced by electrophoretic deposition (EPD). A new type of polyelectrolyte consisting of water, ethanol and isopropyl alcohol was used for EPD process. Collagen (main ligament of human bone) and h-BN (a promising solid lubricant) has been used as supporting materials for biocomposite coatings. The effect of h-BN concentration in the EPD suspension has been investigated. Crystallographic, morphological, spectroscopical, corrosion protection performance, thermal behaviour, mechanical and tribological, topographical and in-vitro biocompatibility investigations have been carried out by XRD, FE-SEM, FTIR, Tafel extrapolation and EIS, TGA/DSC, nanoindentation and nanoscratch, SPM and 12-weeks of immersion into r-SBF, respectively. Corrosion protection performance and mechanical and tribological properties of the coatings have been improved with increase in h-BN concentration in deposition suspension up to 5 g·L−1 and worsen with further increase. The results are encouraging for in-vivo applications of HA/CTS/COL/h-BN biocomposite coatings.