Tafel Extrapolation Method Research Articles

The adsorption and corrosion inhibition of 8-hydroxy-7-quinolinecarboxaldehyde derivatives on C-steel surface in hydrochloric acid

Abstract The protection influence of 8-hydroxy-7-quinolinecarboxaldehyde derivatives against C-steel corrosion was studied in 2 mol·L − 1 HCl solutions at 30 °C. Measurements were conducted under various experimental conditions using weight loss, potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and electrochemical frequency modulation (EFM) techniques. These studies have shown that 8-hydroxy-7-quinolinecarboxaldehyde derivatives are very good “green”, mixed-type inhibitors. Corrosion rates obtained from both EFM and EIS methods are comparable with those recorded using Tafel extrapolation method, confirming validation of corrosion rates measured by the latter. The inhibitive action of these 8-hydroxy-7-quinolinecarboxaldehyde derivatives was discussed in terms of blocking the electrode surface by adsorption of the molecules through the active centers contained in their structures following Langmuir adsorption isotherm. Quantum chemical method was also employed to explore the relationship between the inhibitor molecular properties and its protection efficiency.

Study of Corrosion Behavior of Dicalcium Phosphate-dihydrate (DCPD) Coating Prepared by Large Amplitude Sinusoidal Voltammetry (LASV) Technique on ZW3 Magnesium Alloy

This study is focused on corrosion behavior of dicalcium phosphate-dihydrate (DCPD) coating electrodeposited by large amplitude sinusoidal voltammetry (LASV) technique on ZW3 magnesium alloy in sodium sulphate solution. The electrochemical characteristics of coated and non-coated samples were evaluated by potentiodynamic polarization (PD) tests in 0.1M Na2SO4 solution at the temperature of 22±1°C. The PD curves were analyzed using Tafel extrapolation method. The analyzed values of the corrosion potential and corrosion current density obtained from PD tests proved that DCPD coating can effectively increase corrosion resistance and slow down degradation of ZW3 magnesium alloy in chosen environment.

Sage extract as an inhibitor of steel and copper corrosion

Protection of steel and copper from corrosion was caried out by processing corrosive environment using different concentrations of sage extract (0.5 g/dm3, 1 g/dm3 and 1.5 g/ dm3) as a green inhibitor in 3% NaCl and 4% HCl solutions. The rates of steel and copper corrosion in the solutions prepared were measured using gravimetric analysis and electrochemical methods (the Tafel extrapolation method and electrochemical impedance spectroscopy). The highest level of steel protection (z= 97.5%) in the 3% NaCl solution occurs with the concentartion of sage of 1.5 g/dm3 for a six-hour time interval. Sage concentrations of 1.0 g/dm3 and 1.5 g/dm3 in the 3% NaCl solution exhibit a very good inhibitory action, since the average protction factors are 78.5% and 95.3% respectively. These results prove that sage can be used as a potential inhibitor of steel corrosion in the 3% NaCl solutions. Corrosion protection for steel in the 4% HCl is considerably lower, not more than 64.5%, which means that sage can only be used as a green inhibitor for a shorter period of time. The highest level of copper protection (z=60,04%) in the 3% NaCl is for the sage concentration of 1 g/dm3, whereas for the concentration of 1.5 g/dm3 it is 53% for a six-hour time interval. However, the same solutions for the time intervals of 4 and 24 h have a catalytic action in the process of copper corrosion, so it is not recommended to use sage extract as a green inhibitor for copper in the 3% NaCl. The highest protection factor achieved in the 4% HCl is 59.96% in the solution which contains 1 g/dm3 of sage extract. This value is not sufficent to recommend sage extract as an inhibitor of copper corrosion in the 4% HCl. The results obtained from electrochemical measurements confirm the results obtained by gravimetric analysis, which makes them, therefore, recommendable as fast and relibale methods in corrosion testing.

Corrosion Susceptibility of a 0.35%C Steel in Seawater Electrolyte Using the Electrochemical Method

The Tafel extrapolation and linear polarization methods were used as effective measures for determining the corrosion susceptibility of a spheroidized 0.35%C steel with sea water as the electrolyte. Eight pieces of steel were machined to length 5mm by 10mm in diameter. Two pieces each were heat treated at 600°C, 700°C and 800°C respectively and two pieces left as control. Electro-chemical experiments were carried out to obtain the best potential and anodic current of samples immersed in an electrolyte (seawater) at varying anodic potential of-0.7mv, -0.6mv, -0.5mv and-0.4mv respectively. The results showed that the sample with the least corrosion rate were the samples spheroidized at 700°C. They appeared to have the highest electrode potential value of-0.6mv and 800°C spheroidized samples had the least electrode potential value of-0.65mv at the end of 2000seconds respectively. From the results obtained, the samples spheroidized at 700°C appeared to be most suitable for seawater environment.

Corrosion behaviour of single and double layer hydroxyapatite coatings on 316L stainless steel by plasma spray

AISI316L stainless steel is extensively used in orthopedic and dental applications. However, this alloy exhibits low integration behaviour when it comes in contact with surrounding bone tissue and implant healing duration can be as much as few months. The aim of this study is the fabrication of biocompatible hydroxyapatite (HA) coatings on stainless steel substrate in order to accelerate the process of osseointegration of implants. The biocompatible single layer of Titania (TiO2), Hydroxyapatite and bi-layer TiO2/HA coatings were deposited by atmospheric plasma spray on 316L stainless steel. Coated and uncoated stainless steel specimens were incubated in simulated body fluids and 0.9% NaCl solutions for 1h and 7 days. In vitro electrochemical-corrosion evaluation of coated and uncoated stainless steel specimens have been investigated by Tafel extrapolation and linear polarization methods. Results indicates that corrosion resistance of single layer HA coated stainless steel specimens are superior to single layer TiO2 and bi-layer HA/TiO2 coated stainless steel specimens.

Green inhibitors for corrosion protection in acidizing oilfield environment

Tafel extrapolation method has been employed to determine the corrosion resistance of super austenitic stainless steel (UNS S31254) in a CO2-saturated acidizing oilfield environment. Green inhibitors (Tridax procumbens and Chromolaena odorata extracts) were employed for protection of the alloy in the environment. Over 90% inhibition efficiency was achieved at inhibition dosage of 100ppm for one of the inhibitors. Results showed that both inhibitors are effective for protecting the alloy in the acidizing environment. The result of the adsorption isotherm showed that the adsorption of the extracts on the surface of UNS S31254 is a monolayer and consistent with the Langmuir isotherm.

An Experimental Study of Sintered (Ni-Cr-xAl2O3) Composites

This paper deals with the (Ni-Cr- xAl2O3) metallic composites (MCCs). Restraining of of thermal expansion at adequate mechanical and corrosion properties is the main objective of this work. Composites are fabricated with four weight percentages of (x = 1, 2, 5 and 10% Al2O3). Compacting and sintering has accomplished at (636 MPa) and 1250oC for 7 hrs. All sintered compacts were examined for phases and microstructure featuring. Results have indicated, the incorporation of Al2O3 with the matrix is due to the efficient sintering conditions, that diminishing the grain growth and increasing the softening temperature from 850°C to become 1350°C. Volume expansion appeared in the base sintered composites (NiCr-xAl2O3) due to pores evolution according to SEM observation. As, the Al2O3 has increased, the microhardness and corrosion resistance have improved. DSC results show a clear one exothermic and one endothermic reaction were occurred during the heating cycle. Corrosion behavior of fabricated composites was estimated by polarization curves using Potentiostat at scan rate 3 mV.sec-1. Potential-time measurements showed the formation of protective layer on surface composites compared with Ni-Cr base composite through an obtaining of the nobler open circuit potentials for composites. Corrosion parameters were estimated by the Tafel extrapolation method, these parameters indicated that the corrosion potential shifted toward a positive direction in addition to get lower corrosion current density especially for Ni-Cr/5%Alumina composite.

Impact of anode substrates on electrodeposited zinc over cycling in zinc-anode rechargeable alkaline batteries

Electrochemical behavior of Ag, Bi, Cu, Fe, Ni and Sn substrates on zinc deposition was evaluated over battery cycling by cyclic voltammetry and electrochemical impedance spectroscopy. The effect of Bi, Cu, Ni, and Sn substrates on zinc electrodeposition during battery cycling was investigated using scanning electron microscopy and X-ray diffraction. The corrosion behavior of each metal in 9M KOH and the corrosion rates of zinc plated on each substrate were analyzed by Tafel extrapolation method from the potentiodynamic polarization curves and electrochemical impedance spectroscopy. Although the charge-transfer resistance (Rct) of zinc electrodeposition is lowest on Sn, Sn eventually corrodes on cycling in alkaline media. Use of Ni as a substrate causes zinc to deteriorate on account of rapid hydrogen evolution. Bi and Cu substrates are more suitable for use as current collectors in zinc-anode alkaline rechargeable batteries because of their low corrosion rate and compact zinc deposition over battery cycling.

A study on the corrosion and mechanical properties of duplex coating Ti6Al4V/TiAlBN

Titanium alloys, especially Ti6Al4V, have an excellent combination of properties. However, in many cases their application is limited because of poor wear and corrosion properties. In this research, a surface modification (duplex coating) has been carried out to improve the surface properties of Ti6Al4V. The duplex coating of the Ti6Al4V alloy was conducted with the aim of improving the corrosion resistance and mechanical properties of the alloy. In this study, plasma nitriding of Ti6Al4V was performed using a microwave plasma technique at a temperature 600°C for 1 and 3 h, followed by deposition of TiAlBN coating on plasma-nitrided samples for duplex coating purposes. Microstructural measurement revealed that the duplex coating process produces a relatively smooth and crack-free modified surface layer which is believed able to inhibit the occurrence of corrosion process. The electrochemical behaviour of duplex coating samples and untreated Ti6Al4V was evaluated using the Tafel Extrapolation method and it was found that the duplex coating significantly increased the corrosion protection property. In addition, the duplex surface obtained in this study has a superior surface hardness property compared to untreated Ti6Al4V, especially for samples with the longer nitriding time.

Effect of major degradation products of ethylene glycol aqueous solutions on steel corrosion

The effect of major degradation acid products of ethylene glycol (EG) aqueous solutions, namely glycolic, formic, acetic, and oxalic acids, on the corrosion behavior of low carbon steel was investigated under stirring conditions at 80°C by means of well-established techniques for electrochemical, physico-chemical, and surface analyses. The electrochemical behavior of steel under polarization conditions is dominated by active dissolution of iron with Fe2+ production leading to oxide products and H+ reduction as the cathodic counterpart. No correlation was found between the corrosion current density estimated by Tafel extrapolation method and that determined by the rate of production of Fe2+ under free corrosion conditions. The latter experiments revealed that the nature and the relative proportion of carboxylic acids influence the corrosion behavior of steel. The rate of production of soluble corrosion products increases with the stability and complexation ability of the organic anion towards Fe3+, being more significant in the case of glycolic acid in excess with high chelation propensity. Conversely, formation of Fe2+ and Fe3+ oxalates on iron surface is promoted in the presence of oxalic acid due to a catalytic action on magnetite dissolution. The extent of above processes is compromised if hydrogen bonding interactions between different carboxylic acids are privileged.

Synthesis of novel Schiff Bases containing acryloyl moiety and the investigation of spectroscopic and electrochemical properties

A novel Schiff bases and their acryloyl derivatives were synthesized through the reaction of p-hydroxybenzaldehyde in order of with aniline, p-chloroaniline, p-nitroaniline, p-methylaniline and p-aminobenzoic acid. The structures of these compounds were characterised spectroscopic techniques such of IR, 1H NMR, 13C NMR and Mass spectroscopy. π→π* and n→π* transitions were determined via UV–vis spectroscopy studies performed in EtOH, CHCl3, and DMF. Furthermore, the inhibition efficiencies of these new compounds were investigated on the surface of steel within the solution of 0.1 M NaCl, 0.1 M NaOH and 0.10 M H2SO4 solution via cyclic voltammetry and Tafel extrapolation methods.

Effect of Recasting of Ni-Cr Base Metal Dental Casting Alloys on the Corrosion Rate, Compositional Changes and Ion Release in Artificial Saliva and Saline Solution

Background: Environmental concerns are increasing rapidly, and the industry and public are more concerned about natural resources and recycling. Today, it is equally important to take into account cost, ecological factors in production and recycling of materials used in various fields. Purpose: The aim of this study was to evaluate corrosion rate, compositional changes and ion release of recasted Ni-Cr dental casting alloy Materials and Methods: Commercially available Ni -Cr alloy (Bellabond) was used in the study. The recasting was done without any addition of new alloys and recasted up to six times. Corrosion rate was determined by Tafel extrapolation method in artificial saliva in pH 2.3, 6.7 and in 0.9% saline solution at pH 7.3. The compositional changes were studied by Inductively coupled Plasma – Atomic emission Spectroscopy (ICP-AES) method. Ion release during storage in artificial saliva and saline solution for one week and four weeks was detected by using atomic absorption spectroscopy (AAS). Results: The corrosion rate was found slightly increased with recasting numbers up to six times. The quantities of ions released increased as the recasting number increases. These changes were not clinically significant. During recasting procedure, there was a change in their alloy compositions, which increases the corrosion rate in recasted alloys. Conclusion: The recasting technique can be accepted in dental practices. This study showed the possibilities of safe usage of recasted alloys up to certain generations in dentistry and in later stages if it is not suitable for dentistry it can be directed to other fields of industries, where the biocompatibility is not a major requirement. This lowers the environmental burden, health hazards and protects imbalance of natural resources

A newly synthesized sulphated 8-hydroxyquinoline derivative to effectively control aluminum corrosion in perchloric acid: Electrochemical and positron annihilation studies

The corrosion of aluminum in 1.0M HClO4 was effectively controlled by a newly synthesized sulphated 8-hydroxy-quinoline derivative (8HQD), namely 2-(2-(quinolin-8-yloxy)acetamido)ethyl hydrogen sulfate. Rates of corrosion were monitored as a function of C8HQD (C8HQD: 10−4–10−2M) using Tafel extrapolation method and linear polarization resistance (LPR) measurements. The electron density and corrosion-related defects in corroded and inhibited Al samples were probed using the positron annihilation lifetime (PAL) and positron annihilation Doppler broadening (PADB) techniques. Results were compared with 8-hydroxyquinoline (8HQ) itself. Polarization studies indicated that 8HQD acted as a mixed-type inhibitor with anodic predominance. PAS measurements demonstrated that the PAL components (τi) and their corresponding intensities (Ii) as well as PADB line-shape parameters (S and W) can be used to assess the inhibition performance of the tested materials. Results obtained from the different corrosion evaluation techniques were in good agreement and went parallel with those of PAS measurements. 8HQD was much better than 8HQ in inhibiting Al corrosion in these solutions.

Corrosion of Surface Modified AISI 4340 Steel in Jatropha Biodiesel

The aim of this paper is to study the effect of jatropha curcas biodiesel on the corrosion behavior of surface modified low alloy steel after modification by TIG torch surface melting technique. The coating layer was produced by preplacement of 1 mg/mm2 TiC particulate into the surface of AISI 4340 steel and at heat input of 1344 J/mm using an electric arc generated from the tungsten electrode that melt the powder with substrate material to form a composite layer. The micrograph of the composite coated surface modified steel showed formation of TiC dendrites that densely populated at the of the melt pool which contributes to the high hardness value. The corrosion behavior of the composite coated steel was studied using tafel extrapolation method in biodiesel environment. The surface micrograph after corrosion test shows pitting corrosion holes as a dominant corrosion phenomenon for AISI 4340 steel. The tafel curve showed reduction of corrosion current density of the surface modified steel compared to the alloy street substrate.

Effects Of Aluminum Sputtering On The Corrosion Resistance Of AZ91 Alloy

Abstract The corrosion resistance of a Magnesium alloy is low and needs to be improved. This research aimed at corrosion-resistance improvement by supatterd deposition aluminium film, which is formed on the surface of AZ91 Magnesium-alloy. Corrosion resistance performed polarization curve measurement, was evaluated in quest of the corrosion rate using the Tafel extrapolation method, and conducted surface observation and EDS analysis by SEM. Although corrosion resistance is not improved only by film forming because of defects in film, corrosion resistance is improved by heat treatment for 3 hours by 553K after sputtering. In the case of heat treated at 623K and 673K for 3 hours, magnesium diffuses through the alminium film and reached the surface of the film. Thus, heat treatment at high temperature degrade the corrosion resistance of the film. The optimization of heat treatment after sputtering is important in this method.

Electrochemical Characteristics of Anodized Ti-6Al-4V Alloy

Titanium and its alloys are still popular in different kind of industry. Ti-6Al-4V alloy is usually used due to its two-phased composition, which cause good mechanical properties. Corrosion resistance of this material can be improved by anodic oxidation. This electrochemical method is used to increase the thickness of titanium dioxide. The aim of the research was color anodizing of the Ti-6Al-4V alloy in the 7% H2SO4 acid solution at 20 ± 0.5°C and for 30 seconds at different voltages (15-90V). The electrochemical characteristics were determined by potentiodynamic tests in the 0.1M NaCl solution. The obtained results were analyzed by the Tafel-extrapolation method. Finally, the corrosion current densities and corrosion rates were evaluated. In fact, the corrosion rates of anodized alloys were 6 to 85 times lower against to ground surface.

Electrochemical performance of tungsten electrode as cathode for hydrogen evolution in alkaline solutions

The electro–catalytic activity of the tungsten metal as cathode for hydrogen evolution in alkaline solutions was investigated by open circuit potential measurements, potentiodynamic polarization techniques and electrochemical impedance spectroscopy (EIS). It was found that the onset potential of the hydrogen evolution reaction (HER) on tungsten is in favor of the hydrogen generation at lower overpotential, compared to Pt electrode. The effect of electrolyte concentration, scan rate on the rate of the HER as well as the electrochemical stability of the cathode was studied. The kinetic parameters characteristic for the hydrogen evolution reaction i.e. cathodic transfer coefficient, exchange current density and also corrosion rates were determined using Tafel extrapolation method. The results reveal that tungsten can be considered as a good candidate for hydrogen evolution on large scale and for long term production. The rate of hydrogen evolution is relatively high under low overpotential.

Improvement in Surface Properties of Ti6Al4V Alloy by ZrN Thin Film

Ti6Al4V alloy is attracting attention as a biomaterial due to its excellent mechanical properties, corrosion resistance and super plasticity. However; this alloy contains aluminium and vanadium liable to do serious harm to human bodies. For overcoming surface originated problems, various surface modification techniques have been used on metallic implants. In this study cathodic arc PVD was used to produce ZrN coating with different substrate bias voltage at 20mttor nitrogen gas pressure. Corrosion resistance of Ti6Al4V and ZrN coated Ti6Al4V were investigated by an electrochemical test, at 37°C in normal saline solution. Tafel extrapolation method was used for calculating corrosion rate. ICP-AES studies were carried out to determine amount of ions leached out from samples when kept immersed in normal saline solution. The surface morphology was carried out by XRD. The ZrN coated samples showed variation in the corrosion resistance with varying voltage and the sample coated at-200V showed an optimum corrosion resistance.

Characterization of Nitrogen Implanted Pure Ti in Normal Saline (0.9% NaCl) Solution

Metallic biomaterial like stainless steel, Co-based alloy, Ti and its alloy are widely used as artificial hip joints, bone plates and dental implants. However; this alloy releases ions from the surface liable to do serious harm to human bodies. For overcoming surface originated problems, various surface modification technique have been used on the metallic implants. In this study, the nitrogen was implanted by a process of ion implantation at 60 keV with different fluences of 1 x 1016, 5 x 1016, 1x1017 and 5 x 1017 ions/cm2. Corrosion resistance of Ti and ion implanted Ti were investigated by an electrochemical test, at 37°C in normal saline solution. Tafel extrapolation method was used for calculating corrosion rate. ICP-AES studies were carried out to determine amount of ions leached out from samples when kept immersed in normal saline solution. Corrosion stability and elemental out-diffusion resistance was found to be increased by nitrogen ion implantation. The implanted samples showed variation in the corrosion resistance with varying doses and the sample implanted at 1 X 1017 ions/cm2 showed an optimum corrosion resistance.

Characterization of Nitrogen Implanted Pure Ti in Normal Saline (0.9% NaCl) Solution

Metallic biomaterial like stainless steel, Co-based alloy, Ti and its alloy are widely used as artificial hip joints, bone plates and dental implants. However; this alloy releases ions from the surface liable to do serious harm to human bodies. For overcoming surface originated problems, various surface modification technique have been used on the metallic implants. In this study, the nitrogen was implanted by a process of ion implantation at 60 keV with different fluences of 1 x 1016, 5 x 1016, 1x1017 and 5 x 1017 ions/cm2. Corrosion resistance of Ti and ion implanted Ti were investigated by an electrochemical test, at 37°C in normal saline solution. Tafel extrapolation method was used for calculating corrosion rate. ICP-AES studies were carried out to determine amount of ions leached out from samples when kept immersed in normal saline solution. Corrosion stability and elemental out-diffusion resistance was found to be increased by nitrogen ion implantation. The implanted samples showed variation in the corrosion resistance with varying doses and the sample implanted at 1 X 1017 ions/cm2 showed an optimum corrosion resistance.