Tafel Extrapolation Technique Research Articles

Effect of post-processing on the corrosive behaviour of L-DED Ti-6Al-4V

The study investigates the effect of different post-processing techniques like annealing and cryogenic treatment on the corrosive behaviour on Laser direct energy deposited − Ti-6Al-4 V (LDED-Ti64). The investigation starts with LDED-Ti64 and cast-Ti64, one pair of samples are annealed at 800℃ for 2 h and the other pair of samples are Deep Cryogenic Treated(DCT) at −196℃ for 48 h. The electrochemical corrosion of all the samples are analysed through the tafel extrapolation technique. The results revealed that all the post-processed samples showed improvement in corrosion resistance, especially the annealed ones in comparison to the untreated sample. During annealing the martensitic α’-phases present in untreated samples get converted to β-phase which is a good corrosion inhibitor. During DCT the residual stress relieves and dislocation density improves which restrains electron flow and hence corrosion resistance improves.

Zirconium oxide thin films deposited via DC magnetron sputtering: corrosion and morphological investigation

Purpose The purpose of this study is to investigate the structural, surface roughness and corrosion properties of the zirconium oxide thin films deposited onto SS304 substrates using the direct current (DC) magnetron sputtering technique. Design/methodology/approach DC sputtering at different powers – 80, 100 and 120 W – was used to deposit ZrO2 thin films onto different substrates (Si/SS304) without annealing of the substrate. Atomic force microscope (AFM), energy-dispersive X-ray spectroscopy (EDS), Tafel extrapolation and contact angle techniques were applied to investigate the surface roughness, chemical compositions, corrosion behavior and hydrophobicity of these films. Findings Results showed that the thickness of the deposited film increased with power increase, while the corrosion current decreased with power increase. AFM images indicated that the surface roughness decreased with an increase in DC power. EDS analysis showed that the thin film has a stoichiometric ZrO2 (Zr:O 1:2) composition with basic uniformity. Water contact angle measurements indicated that the hydrophobicity of the synthesized films decreased with an increase in surface roughness. Originality/value DC magnetron sputtering technique is infrequently used to deposition thin films. The obtained thin films showed good hydrophobic and anticorrosion properties. Finally, results are compared with other deposition techniques.

A sustainable approach exploiting Chrysanthemum Coronarium flowers distillation waste as a corrosion suppressor for low carbon steel in monoprotic acid medium through electrochemical and computational evaluations

This study focuses on evaluating a biowaste generated amid the hydrodistillation process of Chrysanthemum Coronarium Flower compounds as a sustainable inhibitor for the corrosion of carbon steel in the hydrochloric medium. Total phenolic and flavonoid contents, phytochemical screening protocols as well as Fourier Transform Infrared (FT-IR) analysis were implemented to examine the phytochemical diversity of the Chrysanthemum Coronarium flowers extract (CCFE). Electrochemical impedance spectroscopy (EIS) as well as Tafel extrapolation techniques were adopted for examining the corrosion suppression efficiency of the liquid waste as a corrosion inhibitor at 293 K. The findings indicated that the CCFE displayed strong corrosion suppression properties on the metal, achieving an impressive efficiency of 82 %. Following a mixed-type inhibition mechanism. Temperature influence in the presence of the CCFE was assessed at a 293–313 K domain, and the combined impact of KI and the CCFE inhibitor was investigated to determine their synergistic effects. Furthermore, an in-depth analysis of the surface morphology of metal was carried out using SEM-EDX analysis to investigate the electrochemical behavior and comprehend alterations occurring on the surface as a result of the CCFE introduction. Moreover, computational analysis through Density Functional Theory (DFT) and Molecular Dynamic simulations (MD) were performed to gain a more comprehensive understanding of the mechanism of electronic adsorption occurring at specific active sites in the presence of the Chrysanthemum Coronarium Flowers compounds.

Microstructural features and corrosion behavior of Inconel 625 components fabricated using Wire and Arc Additively Manufacturing (WAAM)

Wire and arc additive manufacturing (WAAM) is the predominant technique to process Nickel-based superalloys due to its low cost and high flexibility. This article discusses the microstructural features and corrosion resistance of two Inconel 625 parts manufactured using the WAAM technique. Using the WAAM process, two single-walled Inconel 625(IN625) components were produced additively for inter-pass layer temperatures (IPT) of 200 °C and 300 °C. The grain size changed with a change in IPTs, according to an investigation using electron backscatter diffraction (EBSD). The preferred grain orientation changed from the texture {001} < 001> to {001} < 101> as the IPT increased. Potentiodynamic polarization was used to evaluate the corrosion behavior. The corrosion rate of the IPT 300 °C sample is 0.007255 mmpy, while the corrosion rate of the IPT 200 °C sample is 0.01315 mmpy. Tafel’s extrapolation technique calculated the corrosion current density and corrosion current potential. The scanning electron microscope (SEM) explored the corroded area, and the energy-dispersive X-ray spectroscope examined the elemental composition.

Development of Ni-Co-CNT composite coatings for corrosion protection of mild steel in 5% NaCl

In this report, corrosion resistance of Ni-Co-CNT composite coatings on mild steel was studied. The deposition step follows composite-electrodeposition technique. The effect of CNT nanoparticle on corrosion resistance behavior of Ni-Co alloy coatings on mild steel were studied. The Ni-Co bath contents such as electrolytes, stabilizer and additives were optimized by using Hull cell. The optimized amount of CNT particle in the bath was found to be 0.5g/L. The surface modification of Ni-Co alloy coatings in the presence of nanoparticle was studied interms of their corrosion resistance behavior. The Ni-Co-CNT composite coatings was developed at different current densities. The corrosion protection efficacy of the deposited coatings has been studied by using Tafel extrapolation and electrochemical impedance techniques. The Ni-Co-CNT coating was found to be more stable and results showed linear change of potential with time. The result depicted that deposited composite coating on mild steel at a current of 4.0Adm −2 was found to be more corrosion resistance as compared with other current density coatings. This was attributed to decrease of size of the particle with increase of current densities as confirmed by AFM analysis. The chronopotentiometry technique revealed that coating was found to be more stable for several hours at different current densities. The coating obtained at a c.d of 4.0A dm −2 was found be more stable towards corrosion and confirmed by Chrono potentiometric techniques.

Characterization & electrochemical behavior of DC & PC methods of electrodeposited Ni-TiO2-CNTs nanocomposite coatings

Pure Nickel coatings and Nickel-Titanium dioxide-Carbon Nanotubes (Ni-TiO2-CNTs) nanocomposite coatings have been developed on mild steel substrate by Direct Coating (DC) and Pulse Coating (PC) methods of electrodeposition. Plating parameters are optimized. The structure and surface morphology of coatings were carried out using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Analysis of x-ray (EDAX). The corrosion resistance was investigated using Tafel extrapolation and AC impedance techniques. The preferred growth direction for nickel changed from (200) to (111) during inclusion on nanoparticles. A bath composition of 0.75 g l−1 of nanoparticles was optimum for getting coatings with high corrosion resistance and micro hardness.

Effect of sulfur content in the crude oil to the corrosion behavior of internal surface of API 5L X65 petroleum pipeline steel

This work discussed the corrosion behavior of the internal surface of pipeline steel caused by the composition of petroleum products, particularly crude oil. Internal and external pipeline corrosion is the notable cause of pipeline failure in Malaysia&#8217;s oil and gas industry. However, internal corrosion is preferred to be concerned in this work because it involved one of the major corrosive media in the crude oil, such as sulfur content. This project aim is to find the sulfur concentration in the crude oil using Fourier transform infrared spectroscopy and atomic absorption spectroscopy. The corrosion rate, corrosion current and corrosion potential of the API 5L X65 grade carbon steel pipeline in different simulated H2SO4 solution concentrations were carried out using the Tafel extrapolation technique. The corrosion properties of the samples were morphologically measured by means of optical microscope, scanning electron microscope and energy dispersive X-ray analyses. The results showed that the corrosion rate of the pipeline steel significantly increased with the increasing H2SO4 concentrations. The corrosion products formed on the pipeline steel surfaces were mainly composed of iron sulfate, iron sulfide and iron oxide. These findings are crucial to understanding the corrosion behavior caused by the crude oil and should be further investigate with the other possible influence factors such as temperature and petroleum&#8217;s flowing velocity.

Influence of the diffusion annealing process in the corrosion susceptibility of cobalt boride layer immersed in Hank's solution

The corrosion susceptibility of borided CoCrMo alloy exposed to a diffusion annealing process (DAP) and immersed during 7 days in a Hank's solution was evaluated, being compared with the results obtained in the borided CoCrMo alloy and the CoCrMo alloy. Firstly, the CoCrMo alloy was exposed to the powder-pack boriding process during 5 h at 1273 K, to obtain a biphasic layer (CoB-Co2B) with a total thickness around 33 μm. Then, the DAP was performed on the borided CoCrMo alloy during 2 h at 1273 K in an inert argon atmosphere to obtain a 29 μm of monophasic Co2B layer. The corrosion tests were performed by the potentiodynamic polarization technique to estimate the corrosion resistance (Rp) and the corrosion current density (jcorr) by means of the linear polarization and the Tafel extrapolation techniques, respectively. The results showed, in the 7th day of immersion in the Hank's solution, that the borided CoCrMo alloy exposed to the DAP exhibited a corrosion value ~22 times higher (~357 kΩ cm2) than that obtained in the borided CoCrMo alloy (~15 kΩ cm2), reaching a value close to the CoCrMo alloy (~385 kΩ cm2). The corrosion performance of the borided CoCrMo alloy exposed to the diffusion annealing process was attributed to i) the presence of the monophasic Co2B layer and high contents of Cr and Mo on the outer-zone of the borided surface, and ii) the depletion of the B2S3 and CrPO4 species at the surface of the borided CoCrMo alloy. Finally, the borided CoCrMo alloy exposed to the DAP exhibited a corrosion susceptibility around 7%, meanwhile the borided CoCrMo alloy obtained a value of 96%, approximately.

Corrosion behavior of API-5L-X42 petroleum/natural gas pipeline steel in South China Sea and Strait of Melaka seawaters

This work aims to investigate the corrosion effect of different seawaters surrounding Peninsular Malaysia on the carbon steel of the petroleum/natural gas pipeline. The Tafel extrapolation technique has been applied to evaluate the corrosion rate of the pipeline steel and different locations of natural seawaters have been used as the electrolyte solution. In this experiment, carbon steel pipeline, API-5L-X42 was utilized as the sample and the seawaters were taken from several locations in Peninsular Malaysia, specifically at the South China Sea (Terengganu, Kelantan, Pahang) and the Strait of Melaka (Melaka, Johor, Negeri Sembilan). The corrosion rate calculation and the type of corrosion attack also have been discussed on the basis of the morphology and the metal contents of the seawaters. It was found that the corrosion rate of the carbon steel is relatively higher in the Strait of Melaka seawaters than that of the South China Sea seawaters. The corrosion rate results varied from 0.01 to 0.024 mm/year. Immersion test were carried out to examine the corrosion product formed on the surface of the pipe and from the result, localized corrosion (pitting) and uniform corrosion occurred at the specimen’s surface severely for both seawater electrolytes. In summary, South China Sea is more favorable environment for the application of this type of pipeline steel compared to that of Strait of Melaka.

Improvement the Corrosion Resistance of Aluminum Bronze Alloy (Cu-7.7wt%Al) Reinforced by Al2O3 and TiO2 Nanoparticles

This work involves study of corrosion behavior of Aluminum bronze alloy (Cu-7.7wt%Al) reinforced by both nanoparticles of Al2O3 and TiO2 with different percentage (0.6, 1.1, 1.5 and 3 weight percent). Composite materials are prepared by stir casting method with mechanical stirring and magnetic field from induction furnace that used in this work. The copper base alloy reinforced samples were tested to investigate corrosion behavior, by using Tafel extrapolation technique. The Scanning Electron Microscope was used to study the effect of Al2O3 and TiO2 nanoparticles on the topography of surfaces. The results showed that the microstructure of reinforced alloy is composed of a fine dendritic structure of α Cu phase and CuAl2 as intermetallic compound. The samples reinforced with 3wt% of Al2O3 and TiO2 have a lower corrosion rate compared to nano-composites reinforced with 1.5wt% of Al2O3 and TiO2. While the nano-composites reinforced with 1.5wt% of Al2O3 and TiO2 has lower corrosion rate compared to the Cu-Al matrix in 3.5%NaCl solution at ambient temperature.

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.

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.

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.

Inhibition of Mild Steel Corrosion in Acid Medium

Since inhibition is the simplest mechanism used for mitigating the corrosion of metals and alloys, particularly in acidic environments, the present work aims to investigate the inhibiting effect of N-benzyl-N′-phenyl thiourea (BPTU) and N-cyclohexyl-N′-phenyl thiourea (CPTU) on mild steel corrosion in 0.1M HCl medium using the Tafel extrapolation technique. Tafel experiments were conducted with ±250 mV vs. rest potential (RP) in steps of 20 mV from the cathodic side for recording the corrosion currents, and then, the Tafel plot of potential vs. current was drawn for determining the corrosion current density (icorr). The linear polarization method was also used for validating the Tafel results. It was performed by polarizing the specimen with ±20 mV vs. RP in steps of 5 mV, and the corrosion currents were noted. The plot of potential vs. current was drawn for calculating icorr. The study reveals that both BPTU and CPTU act as anodic inhibitors for mild steel in the HCl medium, and good inhibition efficiency (>97%) was evidenced from both the compounds even at elevated temperatures. The study also reveals that the investigated compounds get adsorbed quickly on the steel surface, following Temkin’s adsorption isotherm. The kinetic parameters obtained from the study indicated that the inhibition was governed by a chemisorption mechanism and the presence of inhibitors substantially reduced the metal dissolution in the studied temperature range. The investigation shows that there was a good correlation between the Tafel extrapolation and linear polarization results

Corrosion resistance of Ti-6Al-4V and ASTM F75 alloys processed by electron beam melting

The electron beam melting (EBM) is a useful technique for fabricating alloys that are difficult to machine and require expensive tools as well as the presence of inert atmosphere for further treatments. Under vacuum, EBM provides a controlled environment, reducing the drawbacks of the alloys of their processing in a conventional manner and thereby improving their microstructure, which can enhance corrosion resistance. In the present work, the corrosion resistance of the Ti-6Al-4V and ASTM F75 alloys was evaluated by using the Tafel extrapolation technique with scan rates of 0.05, 0.1 and 0.166mV/s. The corrosion specimens were submerged in a Hank solution to simulate the corporal fluid. The specimens were characterized before and after the corrosion tests by optical microscopy and scanning electron microscopy, as well as a chemical microanalysis by EDS. The microstructural characterization before the corrosion tests revealed a dual phase (α+β) microstructure and α′ martensite in the Ti-6Al-4V alloy. For the ASTM F75 (Co-base) alloy, carbides were observed on the grain boundaries. Corrosion resistance increased in the Ti-6Al-4V alloy, from 0.50 to 0.14mpy, possibly due to the formation of a TiO2 passive layer. For the case of the ASTM F75 alloy, the corrosion rate decreased from 0.21 to 0.14 milli-inches/year (mpy) due to the formation of Cr layer. The corrosion results were observed to be very similar for the EBM fabricated alloys in comparison with more commercially fabricated alloys.

Inhibition effect of a new pyrimidine derivative on the corrosion of mild steel in hydrochloric acid solution

The inhibition effect of a newly synthesized pyrimidine derivative, namely 3-(2-(4-(hydroxymethyl)-1H-1,2,3-triazol-1-yl)ethyl)-2-methyl-6,7,8,9-tetrahydropyrido[1,2-a]pyrimidin-4-one, on the corrosion of mild steel in 1.0 M HCl medium was investigated using the weight loss, the Tafel extrapolation technique and the AC impedance spectroscopy. The effect of the inhibitor concentration, temperature and concentration of the acid mixture media on the inhibitor action was also studied. It was observed that the anti-corrosion efficiency increases with an increase in the inhibitor concentration, but decreases with an increase in temperature. Thermodynamic parameters for the dissolution process were determined. The adsorption of the pyrimidine derivative on the mild steel surface was found to obey the Langmuir adsorption isotherm.

Electrochemical Corrosion of Low Carbon Steel in a Hydrochloric Acid Medium

Inhibition is one of the mechanisms used for mitigating the metallic corrosion, particularly in an acid environment. The present work aims to investigate the inhibiting effect of N-benzyl-N/-phenyl thiourea (BPTU) on the corrosion of low carbon steel in a 0.1 M hydrochloric acid (HCl) solution using a Tafel extrapolation and linear polarization techniques. The study reveals that BPTU acts as an excellent anodic inhibitor for low carbon steel in a HCl solution. The protective efficiency of the compound was found to be more than 97% even at higher temperatures. The study demonstrated that BPTU gets adsorbed on the steel surface, following Temkin’s adsorption isotherm and the inhibition is controlled by a chemisorption mechanism. The investigation shows that the results obtained from the Tafel extrapolation and linear polarization techniques for the corrosion of mild steel in HCl medium were in good agreement. The influence of temperatures and concentrations of BPTU on the corrosion of low carbon steel are also examined in the present work

The Effect of Magnetic Field on Corrosion Inhibitor of Copper in 0.5 M HCl Solution

Corrosion of metals within magnetic field (MF) had been actively studied for better understanding of the corrosion mechanism when the magnetic sources are presented. However, findings regarding the effect of MF on metals are inconclusive, and there is a lack of studies of MF interaction with various corrosion control techniques, such as corrosion inhibitor. In this paper, the effect of MF on the corrosion of copper in 0.5M hydrochloric acid (HCl) solution, with or without corrosion inhibitor were studied. Benzotriazole (BTA), a common copper inhibitor, was chosen as the inhibitor for this study. To determine the effect of MF, a MF of 13 mT, generated using a pair of permanent neodymium magnet, was applied during weight loss and electrochemical tests. The results showed that corrosion inhibition efficiency of BTA decreased when it is under an applied MF. A decrease from 47% to 60% in inhibition efficiency had been observed for all samples in an applied MF. By using Tafel extrapolation technique on the polarization curves, it revealed that MF had increased the corrosion current of copper in HCl, causing a decrease in the inhibition efficiency.

The Corrosion of Copper Metal in HCl Solutions and the effect of Molybdate and Chromate

Dissolution characteristics of copper in hydrochloric acid medium and the effect of potassium chromate and sodium molybdate on the corrosion process have been studied using potentiodynamic technique, and Electro impedance spectroscopy (EIS). corrosion current density ( I corr) were obtained by Tafel extrapolation technique. Charge transfer resistance (R ct) was obtained from the electrochemical impedance spectroscopy (EIS). The corrosion rate was retarded in presence of sodium molybdate mainly because of the adsorption of the inhibitor on the electrode surface and it was found that the optimum concentration of this inhibitor in 1 M HCl was 0.008 M with an protection efficiency 79.17%, while the corrosion rate was accelerated in presence of potassium chromate.