Technical Note:Microbiologically Induced Increase in Corrosion Current Density of Stainless Steel under Cathodic Protection

The present work deals with direct diffusion bonding welding without interlayer of austenitic stainless steel type AISI 304L with Oxygen Free High Conductivity pure copper (OFHC) in vacuum atmosphere (1.5 *10-5 mbr.). The optimum bonding conditions are temperature of 650 ◦C, duration time of 45 min. and the applied stress of 30 MPa, in order to secure a tight contact between the mating surfaces. The corrosion behavior of diffusion bonding joints in 3.5% Nacl is studied to evaluate the corrosion resistance of welding joints by using Potentiodynamic method. The observed microstructure of corroded specimen of optimum diffusion bonding joint shows that the corrosion current density has low value as compared with base materials used. During polarization, galvanic coupling is observed between two materials used. At passivity region, inverse polarity is occurred at 450mV. Therefore, passive stainless steel 304 L behaves as cathode respective to pure copper, the corrosion behavior of the diffusion bonding joint was mostly by copper side. The corrosion results indicate the presence of galvanic effect. The corrosion current density of copper, stainless steel 304L and bond joints condition were (3.66 µA/cm2, 1.62 µA/cm2 and 1.85µA/cm2) respectively. A SEM examination of corroded diffusion bonding joint indicates that the galvanic corrosion happened on copper side. The corrosion rate of bonding joint conditions was 0.85 mpy, which is less than 1%. This means that corrosion resistance of bond joint is more than excellent.

Download Full-text

Optimizing the Required Cathodic Protection Current for Pre-Buried Pipelines Using Electrochemical Acceleration Methods

Materials ◽

10.3390/ma14030579 ◽

2021 ◽

Vol 14 (3) ◽

pp. 579

Author(s):

Nguyen-Thuy Chung ◽

Min-Sung Hong ◽

Jung-Gu Kim

Keyword(s):

Current Density ◽

Cathodic Protection ◽

Potentiodynamic Polarization ◽

Corrosion Current Density ◽

Electrochemical Impedance ◽

Operating Time ◽

Corrosion Current ◽

Buried Pipelines ◽

Soil Corrosion ◽

Surface Corrosion

Several corrosion mitigation methods are generally applied to pipelines exposed to corrosive environments. However, in the case of pre-buried pipelines, the only option for corrosion inhibition is cathodic protection (CP). To apply CP, the required current should be defined even though the pipeline is covered with various oxide layers. In this study, an electrochemical acceleration test was used to investigate the synthetic soil corrosion of a pre-buried pipeline. Potentiodynamic polarization experiments were first conducted to ascertain the corrosion current density in the environment, and galvanostatic measurements were performed to accelerate corrosion according to the operating time. In addition, corrosion current density and the properties of the rust layer were investigated via potentiodynamic polarization tests and electrochemical impedance spectroscopy (EIS) tests. The variation in surface corrosion was subsequently analyzed via optical microscopy (OM) and X-ray diffraction (XRD) measurements. Finally, an empirical equation for the optimized CP current requirement, according to the pipeline service time, was derived. This equation can be applied to any corroded pipeline.

Download Full-text

Influence of Mechanical Deformation on the Corrosion Behavior of AISI 304 Stainless Steel Obtained from Cooking Utensils

CORROSION ◽

10.5006/1.3290382 ◽

2001 ◽

Vol 57 (6) ◽

pp. 557-565 ◽

Cited By ~ 20

Author(s):

V. A. C. Haanappel ◽

M. F. Stroosnijder

Keyword(s):

Stainless Steel ◽

Current Density ◽

Corrosion Current Density ◽

Water Solution ◽

Cold Work ◽

Corrosion Current ◽

304 Stainless Steel ◽

Cyclic Polarization ◽

Aisi 304 ◽

Polarization Measurements

Abstract The corrosion properties of an AISI 304 (UNS S30400) stainless steel food-service utensil were investigated by linear polarization, Tafel plots, and cyclic polarization, performed in a sodium chloride (NaCl)/water solution at 20°C. Different surface area zones of the utensil were distinguished by differences in the amount of residual stress incorporated as a result of cold work. Large differences in corrosion current density and pit formation after cyclic polarization measurements, and as a consequence, in corrosion rates were found between zones with different degrees of deformation. In general, an increasing degree of deformation resulted in a decrease in the corrosion current density, whereas after cyclic polarization the number of pits increased. However, crevice corrosion was always observed after cyclic polarization measurements.

Download Full-text

An electrochemical method to investigate the effects of compound composition on gold dissolution in thiosulfate solution

Green Processing and Synthesis ◽

10.1515/gps-2020-0033 ◽

2020 ◽

Vol 9 (1) ◽

pp. 496-502 ◽

Cited By ~ 1

Author(s):

Zhaohui Zhang ◽

Bailong Liu ◽

Mei Wu ◽

Longxin Sun

Keyword(s):

Dissolution Rate ◽

Current Density ◽

Polarization Resistance ◽

Electrochemical Method ◽

Corrosion Current Density ◽

Corrosion Potential ◽

Corrosion Current ◽

Gold Dissolution ◽

Tafel Polarization ◽

Edta Solution

AbstractThe electrochemical behavior of gold dissolution in the Cu2+–NH3–S2O32−–EDTA solution has been investigated in detail by deriving and analyzing the Tafel polarization curve, as this method is currently widely implemented for the electrode corrosion analysis. The dissolution rate of gold in Cu2+–NH3–S2O32−–EDTA solution was determined based on the Tafel polarization curves, and the effects of various compound compositions in a Cu2+–NH3–S2O32−–EDTA mixture on the corrosion potential and corrosion current density were analyzed. The results showed that the corrosion potential and polarization resistance decreased, whereas the corrosion current density increased for certain concentrations of S2O32−–NH3–Cu2+ and EDTA, indicating that the dissolution rate of gold had changed. The reason for promoting the dissolution of gold is also discussed.

Download Full-text

Structure, Corrosion Resistance, Mechanical and Tribological Properties of ZrB2 and Zr-B-N Coatings

Metals ◽

10.3390/met11081194 ◽

2021 ◽

Vol 11 (8) ◽

pp. 1194

Author(s):

Philipp Kiryukhantsev-Korneev ◽

Alina Sytchenko ◽

Yuriy Kaplanskii ◽

Alexander Sheveyko ◽

Stepan Vorotilo ◽

...

Keyword(s):

Corrosion Resistance ◽

Tribological Properties ◽

Current Density ◽

Corrosion Current Density ◽

Elastic Recovery ◽

Optical Emission ◽

Corrosion Current ◽

Impact Testing ◽

Total Oxidation ◽

Mechanical And Tribological Properties

The coatings ZrB2 and Zr-B-N were deposited by magnetron sputtering of ZrB2 target in Ar and Ar–15%N2 atmospheres. The structure and properties of the coatings were investigated via scanning and transmission electron microscopy, energy dispersion analysis, optical profilometry, glowing discharge optical emission spectroscopy and X-ray diffraction analysis. Mechanical and tribological properties of the coatings were investigated using nanoindentation, “pin-on-disc” tribological testing and “ball-on-plate” impact testing. Free corrosion potential and corrosion current density were measured by electrochemical testing in 1N H2SO4 and 3.5%NaCl solutions. The oxidation resistance of the coatings was investigated in the 600–800 °С temperature interval. The coatings deposited in Ar contained 4–11 nm grains of the h-ZrB2 phase along with free boron. Nitrogen-containing coatings consisted of finer crystals (1–4 nm) of h-ZrB2, separated by interlayers of amorphous a-BN. Both types of coatings featured hardness of 22–23 GPa; however, the introduction of nitrogen decreased the coating’s elastic modulus from 342 to 266 GPa and increased the elastic recovery from 62 to 72%, which enhanced the wear resistance of the coatings. N-doped coatings demonstrated a relatively low friction coefficient of 0.4 and a specific wear rate of ~1.3 × 10−6 mm3N−1m−1. Electrochemical investigations revealed that the introduction of nitrogen into the coatings resulted in the decrease of corrosion current density in 3.5% NaCl and 1N H2SO4 solution up to 3.5 and 5 times, correspondingly. The superior corrosion resistance of Zr-В-N coatings was related to the finer grains size and increased volume of the BN phase. The samples ZrB2 and Zr-B-N resisted oxidation at 600 °C. N-free coatings resisted oxidation (up to 800 °С) and the diffusion of metallic elements from the substrate better. In contrast, Zr-B-N coatings experienced total oxidation and formed loose oxide layers, which could be easily removed from the substrate.

Download Full-text

Evaluation on the Addition of Inhibitor and Surface Treatment to Corrosion Behavior of the Reinforced Steel Bar Embedded in Mortar Specimen

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.744.114 ◽

2017 ◽

Vol 744 ◽

pp. 114-120

Author(s):

Kyung Man Moon ◽

Sung Yul Lee ◽

Jae Hyun Jeong ◽

Myeong Hoon Lee

Keyword(s):

Current Density ◽

Test Specimen ◽

Corrosion Current Density ◽

Corrosion Current ◽

Corrosion Properties ◽

Mortar Specimen ◽

Steel Bar ◽

Steel Bars ◽

Reinforced Steel ◽

One Year

In this study, seven types of mortar test specimens were manufactured with parameters, that is, the surface of the reinforced steel bar was treated with hot dip galvanizing (Zn) and the surface of the test specimen was coated with underwater paint, and four types of inhibitors (DAW, MCI, DCI, and Silcon) were added in mortars respectively. And, the seven types of mortar test specimens were immersed in seawater for 4 years. The corrosion properties of the reinforced steel bars embedded in mortar test specimens were investigated using electrochemical methods. The corrosion potentials of the test specimens with painting on the surface of the specimen and Zn coating on the surface of the steel bar exhibited the noblest and lowest values respectively after one year, however, after 4 years, the specimens of underwater painting and of addition of Silcon inhibitor indicated the noblest and lowest values of corrosion potentials respectively. Furthermore, the painting specimen exhibited the smallest values of corrosion probability as welll as of the corrosion current density, while, addition of MCI inhibitor showed the highest values of both corrosion probability and corrosion current density. Moreover, the painting specimen showed the smallest value of neutralization degree among all the specimens, and the largest value of neutralization degree was observed at the specimen of natural condition (no adding of inhibitor, no painting and no Zn coating). As a result, it is considered that the addition of inhibitors, coating with hot dip galvanizing (Zn), and painting on the surface have the effects not only to inhibit the neutralization degree but also to increase the corrosion resistance of the embedded steel bar.

Download Full-text

Preparation of Ti–Zr-Based Conversion Coating on 5052 Aluminum Alloy, and Its Corrosion Resistance and Antifouling Performance

Coatings ◽

10.3390/coatings8110397 ◽

2018 ◽

Vol 8 (11) ◽

pp. 397 ◽

Cited By ~ 6

Author(s):

Hehong Zhang ◽

Xiaofeng Zhang ◽

Xuhui Zhao ◽

Yuming Tang ◽

Yu Zuo

Keyword(s):

Corrosion Resistance ◽

Surface Modification ◽

Aluminum Alloy ◽

Current Density ◽

Corrosion Current Density ◽

Salt Water ◽

Water Immersion ◽

Chemical Conversion ◽

Corrosion Current ◽

Conversion Coating

A chemical conversion coating on 5052 aluminum alloy was prepared by using K2ZrF6 and K2TiF6 as the main salts, KMnO4 as the oxidant and NaF as the accelerant. The surface morphology, structure and composition were analyzed by SEM, EDS, FT–IR and XPS. The corrosion resistance of the conversion coating was studied by salt water immersion and polarization curve analysis. The influence of fluorosilane (FAS-17) surface modification on its antifouling property was also discussed. The results showed that the prepared conversion coating mainly consisted of AlF3·3H2O, Al2O3, MnO2 and TiO2, and exhibited good corrosion resistance. Its corrosion potential in 3.5 wt % NaCl solution was positively shifted about 590 mV and the corrosion current density was dropped from 1.10 to 0.48 μA cm−2. By sealing treatment in NiF2 solution, its corrosion resistance was further improved yielding a corrosion current density drop of 0.04 μA cm−2. By fluorosilane (FAS-17) surface modification, the conversion coating became hydrophobic due to low-surface-energy groups such as CF2 and CF3, and the contact angle reached 136.8°. Moreover, by FAS-17 modification, the corrosion resistance was enhanced significantly and its corrosion rate decreased by about 25 times.

Download Full-text

Electrochemical Characteristics of Lanthanum Hexaboride in the Environments Containing S2-

Materials Science Forum ◽

10.4028/www.scientific.net/msf.663-665.473 ◽

2010 ◽

Vol 663-665 ◽

pp. 473-476

Author(s):

Shu Qi Zheng ◽

Chang Feng Chen ◽

Rui Jing Jiang ◽

Dan Ni Wang

Keyword(s):

Partial Pressure ◽

Corrosion Behavior ◽

Current Density ◽

Corrosion Current Density ◽

Corrosion Potential ◽

Corrosion Current ◽

Lanthanum Hexaboride ◽

Electrochemical Characteristics

In the environment with H2S/CO2 or Na2S, the corrosion behavior of Lanthanum hexaboride (LaB6) was investigated by electrochemistry methods. The results indicated that the corrosion potential (Ecorr) and Rf of LaB6 increased as the partial pressure of H2S increased, while the corrosion current density (Icorr) decreased. In the environment containing Na2S, as the content of Na2S increased, the corrosion potential (Ecorr) and Rf of LaB6 decreased, while the corrosion current density (Icorr) increased. Thus, the addition of H2S into the environment with H2S/CO2 would inhibit the corrosion of LaB6; while in the environment containing Na2S, the increasing of the content of Na2S would accelerate the corrosion of LaB6.

Download Full-text