scholarly journals Effect of Laminar Flow on the Corrosion Activity of AA6061-T6 in Seawater

Metals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 175
Author(s):  
Gloria Acosta ◽  
Lucien Veleva ◽  
Luis Chávez ◽  
Juan L. López
Keyword(s):  
Laminar Flow ◽  
Open Circuit Potential ◽  
Electrochemical Behaviour ◽  
Corrosion Current ◽  
Open Circuit ◽  
Flow Conditions ◽  
Metal Interface ◽  
Intermetallic Particles ◽  
Power Spectral ◽  
Surface Changes

The electrochemical behaviour and surface changes on AA6061-T6 alloy exposed to Caribbean seawater from the Cozumel Channel for 30 days under laminar flow (0.1 m s−1) were studied, contrasting then with stationary (no flow) conditions. Monitoring of open-circuit potential and current fluctuations, both considered as electrochemical noise (EN), were employed as two nondestructive methods. The calculated corrosion current, based on Rn, was one order higher in laminar flow. The fluctuations of current were transformed in the frequency domain. Their power spectral density (PSD) plots were obtained in order to gain information concerning the dynamic of the spontaneous release of energy during the corrosion process. The value of the exponent β in PSD graphs suggested that the localised corrosion on AA6061-T6 surface occurs as a persistent stationary process, in which dynamic is controlled by oxygen diffusion and its renewal at the metal interface. The changes in the morphology and elemental composition of the formed layers revealed that the localized attacks occurred in the vicinity of intermetallic particles rich in Fe and Cu, which act as cathodes.

scholarly journals Galvanic Corrosion of Copper / Nickel-Chrome Alloy in an Agitated Sulfuric Acid Solution

2018 ◽  
Vol 21 (1) ◽  
pp. 133
Author(s):  
Samar S. Hussein ◽  
Basim O. Hasan ◽  
Naseer A. Al-Haboubi
Keyword(s):  
Sulfuric Acid ◽  
Acid Solution ◽  
Sulfuric Acid Solution ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Galvanic Corrosion ◽  
Corrosion Current ◽  
Open Circuit ◽  
Flow Conditions ◽  
Galvanic Current

Galvanic corrosion of Nickel-Chrome alloy (Ni-Cr alloy) and Copper (Cu) coupled in 5% sulfuric acid solution was investigated. The effects of agitation velocity, temperature, and time on the galvanic corrosion current and the weight loss of both metals in both free corrosion and galvanic corrosion were investigated. The trends of open circuit potential (OCP) of each metal and galvanic potential (Eg) of the couple were also determined. The results showed that Cu was cathodic relative to Ni-Cr alloy in galvanic couple and the corrosion potential of the couple (Ni- Cr alloy /Cu) was between the values of the two single components because the OCP of copper shifted to positive with the increase in velocity. Under stagnant conditions initially the galvanic current was more negative then shifted to the positive with time. The corrosion of Ni-Cr alloy decreased with time because the passivation layer was formed on the surface. Under flow conditions, the galvanic current sharply shifted to the negative direction (increase galvanic current from Ni-Cr alloy (anode) to Cu (cathode) during the first few minutes.

scholarly journals From Waste to Valuable Resource: Lignin as a Sustainable Anti-Corrosion Coating

Coatings ◽  
2018 ◽  
Vol 8 (12) ◽  
pp. 454 ◽  
Author(s):  
Arman Dastpak ◽  
Kirsi Yliniemi ◽  
Mariana de Oliveira Monteiro ◽  
Sarah Höhn ◽  
Sannakaisa Virtanen ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Steel Corrosion ◽  
Linear Sweep Voltammetry ◽  
Corrosion Current ◽  
Polymer Coatings ◽  
Open Circuit ◽  
Linear Sweep ◽  
Cyclic Potentiodynamic Polarization

In this study, a waste of biorefinery—lignin—is investigated as an anticorrosion coating on stainless steel. Corrosion behavior of two lignin types (hardwood beech and softwood spruce) was studied by electrochemical measurements (linear sweep voltammetry, open circuit potential, potentiostatic polarization, cyclic potentiodynamic polarization, and electrochemical impedance measurements) during exposure to simulated body fluid (SBF) or phosphate buffer (PBS). Results from linear sweep voltammetry of lignin-coated samples, in particular, demonstrated a reduction in corrosion current density between 1 and 3 orders of magnitude cf. blank stainless steel. Furthermore, results from cross cut adhesion tests on lignin-coated samples demonstrated that the best possible adhesion (grade 0) of ISO 2409 standard was achieved for the investigated novel coatings. Such findings suggest that lignin materials could transform the field of organic coatings towards more sustainable alternatives by replacing non-renewable polymer coatings.

scholarly journals Mechanical and Corrosion Properties of Mg-Based Alloys with Gd Addition

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1775 ◽  
Author(s):  
Aneta Kania ◽  
Ryszard Nowosielski ◽  
Agnieszka Gawlas-Mucha ◽  
Rafał Babilas
Keyword(s):  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Orthopedic Implants ◽  
Corrosion Current ◽  
Medical Application ◽  
Open Circuit ◽  
Dendritic Microstructure ◽  
Corrosion Properties ◽  
Electrochemical Parameters ◽  
Mechanical And Corrosion Properties

Magnesium alloys with rare earth metals are very attractive materials for medical application because of satisfactory mechanical properties. Nevertheless, low corrosion resistance is an obstacle in the use of Mg alloys as resorbable orthopedic implants. The paper presents results of mechanical and corrosion properties of MgCa5-xZn1Gdx (x = 1, 2, and 3 wt. %) alloys. Based on the microscopic observations it was stated that the studied alloys show a dendritic microstructure with interdendritic solute rich regions. The phase analysis reveals an occurrence of α-Mg and Mg2Ca, Ca2Mg6Zn3 phases that are thermodynamic predictions, and stated Mg26Zn59Gd7 phases in MgCa5-xZn1Gdx (x = 1, 2, and 3 wt. %) alloys. The Mg26Zn59Gd7 phases are visible as lamellar precipitations along interdendritic regions. It was confirmed that an increase of Gd content from 1 to 3 wt. % improves ultimate tensile (Rm; from 74 to 89 MPa) and compressive strength (Rc; from 184 to 221 MPa). Moreover, the studied alloys are active in Ringer’s solution. They are characterized by an increase of corrosion potential (Ecorr) of about 150 mV in comparison with values of open circuit potential (EOCP). The best electrochemical parameters (e.g., corrosion current density, icorr, polarization resistance, Rp, and Ecorr) were obtained for the MgCa3Zn1Gd2 alloy.

A study of the electrochemical behaviour of cobalt in aqueous H2CO3/HCO3–/CO32– solutions at pH 7–9

2004 ◽  
Vol 82 (5) ◽  
pp. 583-594 ◽  
Author(s):  
Stéphan Simard ◽  
Danick Gallant
Keyword(s):  
Open Circuit Potential ◽  
Competitive Adsorption ◽  
Carbonic Acid ◽  
Acid Corrosion ◽  
Electrochemical Behaviour ◽  
Open Circuit ◽  
Corrosion Process ◽  
Rotating Disc ◽  
Solution Interface ◽  
Potential Decay

The electrochemical behaviour of a cobalt rotating electrode in H2CO3/HCO3–/CO32– aqueous solutions was investigated in the pH region from 7 to 9. The effects of H2CO3/HCO3–/CO32– concentration, pH, and the presence of phosphates as inhibitors was explored using a rotating disc electrode at 1000 rpm. Some potentiodynamic experiments indicate that for pH 8.5 and higher, carbonate and bicarbonate species play a key role on the rate of electrooxidation of cobalt. For pH lower than 8.5, the electrochemical behaviour of cobalt changes drastically and very aggressive corrosion is observed. The involvement of carbonic acid must be considered in the corrosion process of cobalt in this pH region. The study of passive film potential decay under open circuit potential and galvanostatic reduction was performed on preanodized cobalt electrodes in solutions of various compositions. These experiments indicated the phenomena occurring at the electrode–solution interface during the corrosion process. A mechanism involving competitive adsorption of different species is suggested on the basis of the experimental evidence.Key words: cobalt, bicarbonate, phosphate, carbonic acid, corrosion.

scholarly journals Experimental evaluation of corrosion resistance of the alloys used in the fixed dental prosthesis

2015 ◽  
Vol 61 (2) ◽  
pp. 117-120
Author(s):  
Costin Coman ◽  
◽  
Raluca Monica Comăneanu ◽  
Violeta Hâncu ◽  
Horia Mihail Barbu ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Current Density ◽  
Applied Research ◽  
Open Circuit Potential ◽  
Corrosion Potential ◽  
Artificial Saliva ◽  
Corrosion Current ◽  
Open Circuit ◽  
Metal Alloys ◽  
Fixed Dental Prosthesis

Objectives. In this study we evaluated corrosion resistance of three types of metal alloys (two NiCr and one CoCr). Methods. Samples (coded A, B, C) of circular shape, with dimensions 13 x 1.5 mm, sanded and polished, were introduced in Fusayama Meyer artificial saliva at pH 5.2 and 37 ± 0.5°C and tested in terms of corrosion resistance with a potentiostat/galvanostat (model 4000 PARSTAT, Princeton Applied Research). Results. Open circuit potential EOC [mV] ranged between 21.316 and 5.75. Corrosion potential Ecor [mV] was between -73.536 and -395.662, and the corrosion current density icor [A/cm2] was between 1.237 x 10-6 and 905.13 x 10-9. Conclusion. The best corrosion behavior in Fusayama Meyer artificial saliva at pH 5.2 and at a temperature of 37 ± 0.5°C is the alloy A, followed by the alloy C.

scholarly journals Corrosion behavior of GeO2 and Sc2O3 Coatings on AZ31 Alloy

2021 ◽  
Vol 37 (2) ◽  
pp. 433-439
Author(s):  
L. Sutha ◽  
A. Cyril
Keyword(s):  
Open Circuit Potential ◽  
Corrosion Current ◽  
Az31 Alloy ◽  
Germanium Dioxide ◽  
Electrode System ◽  
Open Circuit ◽  
X Ray ◽  
X Ray Crystallography ◽  
Corrosion Studies ◽  
Surface Examination

In this work, GeO2 (germanium dioxide) and Sc2O3 (scandium trioxide) were developed as coatings on AZ31 alloy using polymer binder. The coatings were characterized using X-ray crystallography procedure (XRD), infrared spectrum of absorption or emission of a solid procedure (FTIR), Raman spectroscopy procedure, surface examination by FESEM. The corrosion studies were analyzed using a three electrode system in 3.5% NaCl electrolyte. The bare AZ31 alloy showed open circuit potential (Ecorr) of -1.7 V (SCE) and the corrosion current density (icorr) of 3.4 x 10-4 mA/cm2, while the Sc2O3 coated AZ31 alloy exhibited Ecorr of -1.4 V (SCE) and the icorr of 5.4 x 10-9 mA/cm2 and while the GeO2 coated AZ31 alloy exhibited Ecorr of -1.3 V (SCE) and the icorr of 2.59 x 10-9 mA/cm2. The results reveal that the GeO2 coated AZ31 alloy demonstrated higher corrosion resistance than of bare AZ31 alloy and Sc2O3 coated AZ31 alloy.

scholarly journals Influence of Ultrasonic Excitation Sealing on the Corrosion Resistance of HVOF-Sprayed Nanostructured WC-CoCr Coatings under Different Corrosive Environments

Coatings ◽  
2019 ◽  
Vol 9 (11) ◽  
pp. 724 ◽  
Author(s):  
Zhang ◽  
Hong ◽  
Lin ◽  
Zheng
Keyword(s):  
Corrosion Resistance ◽  
Atmospheric Pressure ◽  
Room Temperature ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Corrosion Current ◽  
Aluminum Phosphate ◽  
Open Circuit ◽  
Corrosive Environments ◽  
Oxygen Fuel

The corrosion behavior of unsealed and sealed high-velocity oxygen-fuel (HVOF)-sprayed nanostructured WC-CoCr cermet coatings under different corrosive environments was investigated using scanning electron microscopy (SEM), open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Ultrasonic excitation sealing with aluminum phosphate was performed in an external ultrasonic bath with the frequency of 40 kHz at atmospheric pressure and room temperature. SEM micrographs revealed that the exposed area of the coating was effectively reduced by the coverage of aluminum phosphate sealant on the majority of pores. Electrochemical measurements demonstrated that the sealant with the help of ultrasonic energy could shift the corrosion potential to a more noble direction, reduce the corrosion current density, increase the resistance of charge transfer, and effectively improve the corrosion resistance of the coating in both 3.5 wt % NaCl and 1 mol·L−1 HCl solutions.

Electrochemical Aspects of Etching and Passivation of Silicon in Alkaline Solutions

1995 ◽  
Vol 386 ◽  
Author(s):  
Joong S. Jeon ◽  
Srini Raghavan
Keyword(s):  
Current Density ◽  
Corrosion Current Density ◽  
Open Circuit Potential ◽  
Corrosion Current ◽  
Open Circuit ◽  
High Resistivity ◽  
Alkaline Solutions ◽  
Current Densities ◽  
Passivation Potential ◽  
P Type

ABSTRACTElectrochemical polarization experiments were performed on Si wafers in ammoniacal solutions maintained at a pH in the range of 9.5 to 11.5. Anodic polarization of silicon yielded curves which are typical for materials that undergo passivation. The values of open circuit potential and passivation potential for p-type Si wafers were more anodic than for the n-type Si wafers. Corrosion current density of p-type Si wafers of low resistivity was lower than that of wafers of high resistivity. Corrosion current densities correlated well with surface roughness induced in alkaline solutions. Addition of surfactant or H2O2 to alkaline solutions reduced critical current density for passivation and corrosion current density.

Study on the Impact of Welding on the Corrosion Properties of AA 6061 T6

2014 ◽  
Vol 575 ◽  
pp. 210-213
Author(s):  
Elsadig Mahdi ◽  
E. Eltai
Keyword(s):  
Pitting Corrosion ◽  
Heat Affected Zone ◽  
Open Circuit Potential ◽  
Welding Process ◽  
Corrosion Current ◽  
Open Circuit ◽  
Nacl Solution ◽  
Corrosion Properties ◽  
The Impact ◽  
Alloy 6061

Aluminium alloy 6061 T6 circular specimens were joined using TIG welding method. AlMg5 was used as filler. The corrosion behavior of welded and un-welded AA 6061 T6 was investigated using potentiodynamic and open circuit potential (OCP) measurements. Specimens were immersed in 3.5 (wt %) NaCl solution. Different zones with different corrosion properties were created as a result of the welding process. Results reveals that sever pitting corrosion has taken place on the heat affected zone (HAZ); the corrosion current of HAZ was increased. The measured potential of HAZ was more negative and largely fluctuated comparing to base metal (BM).

scholarly journals Corrosion Resistance Test of Electroplated Gold and Palladium Using Fast Electrochemical Analysis

Coatings ◽  
2019 ◽  
Vol 9 (6) ◽  
pp. 405
Author(s):  
Walter Giurlani ◽  
Patrick Marcantelli ◽  
Francesco Benelli ◽  
Daniele Bottacci ◽  
Filippo Gambinossi ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Standardized Tests ◽  
Open Circuit Potential ◽  
Electrochemical Impedance ◽  
Salt Spray ◽  
Corrosion Current ◽  
Electrochemical Analysis ◽  
Open Circuit ◽  
Metal Coatings ◽  
High Impedance

Noble metal coatings are commonly employed to improve corrosion resistance of metals in the electronic and jewellery industry. The corrosion resistance of electroplated goods is currently determinate with long, destructive and almost subjective interpretation corrosion tests in artificial atmosphere. In this study we present the application of electrochemical analysis to obtain fast and numerical information of the antiaging coating. We performed open circuit potential (OCP) and corrosion current measurement; we employed also the electrochemical impedance spectroscopy (EIS), commonly applied to organic or passivated metal with high-impedance, to find the best option for noble low-impedance coating analysis. For comparison, traditional standardized tests (damp heat ISO 17228, salt spray ISO 9227 and sulphur dioxide ISO 4524) were also performed.

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