scholarly journals Mechanism of Corrosion in Porcelain Insulators and Its Effect on the Lifetime

2020 ◽  
Vol 10 (1) ◽  
pp. 423 ◽  
Author(s):  
Taeyong Kim ◽  
Youn-Jung Lee ◽  
Simpy Sanyal ◽  
Jung-Wook Woo ◽  
In-Hyuk Choi ◽  
...  
Keyword(s):  
Crevice Corrosion ◽  
Galvanic Corrosion ◽  
Zinc Coating ◽  
Industrial Area ◽  
Sea Salt ◽  
Corrosion Mechanism ◽  
Maximum Lifetime ◽  
Geographical Factors ◽  
Porcelain Insulators ◽  
Corrosion Mechanisms

Porcelain insulators should be exchanged periodically, but their lifetime is not clearly defined. One factor that affects service life is corrosion occurring at the pin and cap—each of which is made of iron with a zinc coating. A number of porcelain insulators used for different lengths of time in different locations are gathered, and the corrosion mechanisms of the cap and pin are investigated. The corrosion mechanism of the cap is mainly galvanic corrosion while that of the pin is primarily electrolytic and crevice corrosion as well as galvanic corrosion. Although time is an important factor in corrosion, it is found that corrosion is more influenced by geographical factors. Since the amount of acid rain and sea salt—each of which causes rapid rusting—is dependent on geographical factors, the location of where porcelain insulators are installed should be considered when predicting their lifetime. Theoretically, if there is only galvanic corrosion occurring, the expected lifetime is 56 years in an industrial area when the zinc coating has a thickness of 75 µm. Previous articles dealing with aging have predicted the maximum lifetime of porcelain insulators used in Korea to be approximately 30 years. To prolong the lifetime of porcelain insulators, further study is required in which the use of zinc alternatives, or waterproof coatings (in addition to the zinc coating), could be examined.

Pitting corrosion and crevice corrosion behaviors of titanium alloy overlapped with aluminized PVC film in neutral salt spray

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Longfei Xie ◽  
Wenlong Zhou ◽  
Shiwen Zou ◽  
Xuesong Fu
Keyword(s):  
Crevice Corrosion ◽  
Graphical Model ◽  
Electrochemical Impedance ◽  
Galvanic Corrosion ◽  
Salt Spray ◽  
Corrosion Mechanism ◽  
Neutral Salt ◽  
X Ray ◽  
Pvc Film ◽  
Corrosion Behaviors

Abstract This paper presents a research on the corrosion behavior of Ti-15-3 alloy overlapped with aluminized PVC film in salt spray. It was found that severe corrosion occurred on aluminized PVC film in the coupled regions because of crevice corrosion and/or galvanic corrosion whereas Ti-15-3 alloy in the coupled regions experienced minor corrosion. Scanning electron microscope and Energy-dispersive X-ray spectroscopy analyses demonstrated the corrosion products adhered to the surface of Ti-15-3 alloy within the crevice. To evaluate the effect of aluminized PVC film on the crevice corrosion of Ti-15-3 alloy in salt spray condition, it is necessary to compare with the corrosion resistance of Ti-15-3 overlapped with polytetrafluoroethylene (PTFE) in different neutral salt spray. Further, the tests were performed by electrochemical impedance spectroscopy and potentiodynamic polarization. Combining the graphical model, an in-depth understanding of the crevice and galvanic corrosion mechanism of Ti-15-3 alloy overlapped with aluminized PVC film has been revealed.

scholarly journals Effect of Benzotriazole on the Localized Corrosion of Copper Covered with Carbonaceous Residue

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 2722
Author(s):  
Yun-Ho Lee ◽  
Min-Sung Hong ◽  
Sang-Jin Ko ◽  
Jung-Gu Kim
Keyword(s):  
Oxygen Concentration ◽  
Photoelectron Spectroscopy ◽  
Crevice Corrosion ◽  
Galvanic Corrosion ◽  
Tap Water ◽  
Energy Dispersive Spectrometer ◽  
Copper Surface ◽  
Localized Corrosion ◽  
Electrochemical Tests ◽  
Corrosion Mechanisms

Carbonaceous residues on copper pipes during the manufacturing process are known to be one of the main causes of pitting corrosion on copper pipes. This study examined the corrosion-inhibiting effect of benzotriazole (BTA) on C12200 copper pipes with carbonaceous film in synthetic tap water. In the absence of BTA, localized corrosion mechanisms due to galvanic corrosion, crevice corrosion, and oxygen-concentration cell were proposed in the boundary part of the carbonaceous film on the copper through X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy dispersive spectrometer (EDS) analyses. Electrochemical tests showed that BTA inhibits corrosion by forming Cu−BTA complexes on all over the copper surface where carbonaceous film is present. BTA mitigates galvanic corrosion and crevice corrosion at the boundary of the carbonaceous film and suppresses the formation of oxygen-concentration cells through the formation of a Cu−BTA complex.

scholarly journals Investigation of Zirconium Effect on the Corrosion Resistance of Aluminum Alloy Using Electrochemical Methods and Numerical Simulation in an Acidified Synthetic Sea Salt Solution

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1982 ◽  
Author(s):  
Yong-Sang Kim ◽  
Jong Park ◽  
Byeong-Seon An ◽  
Young Lee ◽  
Cheol-Woong Yang ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Microprobe Analysis ◽  
Electron Microprobe Analysis ◽  
Galvanic Corrosion ◽  
Sea Salt ◽  
Al Alloy ◽  
Alloying Element ◽  
Intermetallic Particles ◽  
Transmission Electron ◽  
Corrosion Simulation

Corrosion resistance of Zr that has been added to an Al alloy (U1070) is higher than that of a commercial Al alloy (A1070). A decreasing number and size of Al3Fe intermetallic particles (IMPs) were observed by electron microprobe analysis and transmission electron microscopy. Based on the numerical corrosion simulation, it was confirmed that decreasing the number and size of IMPs was favorable for improving the corrosion resistance of the Al alloy due to the reduction of the galvanic effect. In addition, Al3Zr was found to be insignificant in promoting galvanic corrosion within the Al matrix. Thus, Zr is an advantageous alloying element for improving the corrosion resistance of the Al alloy.

scholarly journals Effects of Variations in Salt-Spray Conditions on the Corrosion Mechanisms of an AE44 Magnesium Alloy

2010 ◽  
Vol 2010 ◽  
pp. 1-10 ◽  
Author(s):  
Holly J. Martin ◽  
M. F. Horstemeyer ◽  
Paul T. Wang
Keyword(s):  
Galvanic Corrosion ◽  
Salt Spray ◽  
Chloride Ions ◽  
General Corrosion ◽  
Multiple Exposure ◽  
Test Conditions ◽  
Lightweight Alloys ◽  
Pit Nucleation ◽  
Corrosion Mechanisms ◽  
By Products

The understanding of how corrosion affects magnesium alloys is of utmost importance as the automotive and aerospace industries have become interested in the use of these lightweight alloys. However, the standardized salt-spray test does not produce adequate corrosion results when compared with field data, due to the lack of multiple exposure environments. This research explored four test combinations through three sets of cycles to determine how the corrosion mechanisms of pitting, intergranular corrosion, and general corrosion were affected by the environment. Of the four test combinations, Humidity-Drying was the least corrosive, while the most corrosive test condition was Salt Spray-Humidity-Drying. The differences in corrosivity of the test conditions are due to the various reactions needed to cause corrosion, including the presence of chloride ions to cause pit nucleation, the presence of humidity to cause galvanic corrosion, and the drying phase which trapped chloride ions beneath the corrosion by-products.

The Effect of Water Vapour and Sulphur on Corrosion Mechanisms of Steels

2008 ◽  
Vol 595-598 ◽  
pp. 841-849
Author(s):  
Satu Tuurna ◽  
Sanni Yli-Olli ◽  
Liisa Heikinheimo
Keyword(s):  
Water Vapour ◽  
Metal Surface ◽  
Corrosion Mechanism ◽  
Sulphur Compounds ◽  
Boiler Furnace ◽  
Effect Of Water ◽  
Kraft Recovery Boilers ◽  
Recovery Boilers ◽  
Corrosion Mechanisms ◽  
Test Atmosphere

It is well known that water vapour accelerates oxidation; however different gas conditions and material compositions affect the mechanism. The paper addresses this issue from two different application areas; biomass and kraft recovery boilers. In these applications water vapour and sulphur are simultaneously affecting the corrosion mechanism, though the mechanisms are different. Low-alloyed steels were exposed to an atmosphere containing different amounts of water vapour at temperatures of 420, 550 and 600°C. Under oxidising conditions increasing water content generally accelerates oxidation. However, presence of SO2 in moist atmosphere retards oxidation at high temperatures. The phenomenon is seen at low temperatures with higher chromium contents. Stainless steel 304L was tested in an atmosphere containing hydrogen sulphide and carbon monoxide with and without water vapour at a temperature of 440°C to simulate elevated kraft recovery boiler furnace conditions. The tests showed that water vapour in the test atmosphere produces a protective spinel oxide on the metal surface. In tests without water vapour, the initial scales at metal surface were different sulphur compounds and intensive sulphidation occurred. The effect of water vapour on the sulphidation mechanism is addressed in the paper through the described tests and thermodynamic modelling.

scholarly journals Corrosion Behaviors of the Eutectic Structure in Zn-Al-Mg Alloy Coated Steel in Chloride Containing Aqueous Environment

2020 ◽  
Vol 58 (9) ◽  
pp. 610-616
Author(s):  
Jae-Won Lee ◽  
Se-Young Oh ◽  
Bora Park ◽  
Min-Suk Oh ◽  
Sung Jin Kim
Keyword(s):  
Coating Layer ◽  
Early Stage ◽  
Galvanic Corrosion ◽  
Salt Spray ◽  
Eutectic Structure ◽  
Mg Alloy ◽  
Aqueous Environment ◽  
Corrosion Mechanism ◽  
Coated Steel ◽  
Corrosion Behaviors

To clearly understand the effect of the eutectic structure in the Zn-Al-Mg alloy coating on the corrosion behaviors in chloride containing aqueous environments, a bulk Zn-MgZn<sub>2</sub> sample was fabricated by diffusion bonding process, and a variety of experiments, such as electrochemical polarization and galvanic corrosion measurements, salt spray tests, and cyclic corrosion tests, were carried out. This study revealed that the corrosion potential values of MgZn<sub>2</sub> and Zn samples exposed to a 5 wt.% of NaCl solution were approximately -1.5 and -1 VSCE, respectively, and the MgZn<sub>2</sub> showed a higher corrosion current density than Zn at the early stage of corrosion. The continued dissolution of MgZn<sub>2</sub> phase from the eutectic structure in the coating layer provides not only sacrificial protection, but also environmental conditions for the co-formation of two types of corrosion products (simonkoleite (Zn<sub>5</sub>(OH)<sub>8</sub>Cl<sub>2</sub>·H<sub>2</sub>O) and hydrotalcite (ZnAl<sub>2</sub>(OH)<sub>6</sub>Cl<sub>2</sub>·H<sub>2</sub>O)) which have an inhibiting effect on the outer surface. The formation areas and kinetics of the two products on the coating surface were different, and they were greatly dependent upon the types of eutectic structures in the coating layer. Based on the results, a modified anti-corrosion mechanism of Zn-Al-Mg alloy coated steel sheet in chloride containing aqueous environment was proposed.

scholarly journals Research Progress on Corrosion of Equipment and Materials in Deep-Sea Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Sheng Chen ◽  
Liping Qiu ◽  
Shaofang Sun ◽  
Junyi Yang ◽  
Qinghua Meng ◽  
...  
Keyword(s):  
Deep Sea ◽  
Hydrothermal Field ◽  
Research Progress ◽  
Research Trend ◽  
Corrosion Mechanism ◽  
Material Research ◽  
Hydrothermal Temperature ◽  
Field Environment ◽  
Materials Research ◽  
Corrosion Mechanisms

The deep sea is the frontier of materials research in the 21st century. Owing to the particularity of pressure (15–120 MPa), hydrothermal temperature (90–400°C), and explosive fluid (strong H2S) in the deep-sea hydrothermal field environment, the research on the corrosion mechanism of service materials in this environment under the coupling action of many harsh factors is almost blank. It has become the bottleneck of equipment and material research and development for China to explore the deep sea. This paper reviews the research progress of corrosion mechanisms of deep-sea environmental materials at home and abroad, and forecasts the research trend and difficulties in this field, especially in the deep-sea hydrothermal field. At the same time, it points out the urgency of the construction of harsh environment materials platform and its relevance to the discipline construction of marine college.

Crevice Corrosion of Low-Pressure Steam Turbine Materials in the Boiler Water Contained Impurity Ions

2017 ◽  
Vol 737 ◽  
pp. 192-197
Author(s):  
Li Bin Niu ◽  
Katsuyuki Kobayashi
Keyword(s):  
Steam Turbine ◽  
Pitting Corrosion ◽  
Crevice Corrosion ◽  
Steel Plate ◽  
Electrochemical Corrosion ◽  
Low Pressure ◽  
Corrosion Mechanism ◽  
Boiler Water ◽  
Sulfate Ions ◽  
Single Plate

Crevice corrosion of 3.5NiCrMoV and 13Cr steels, which are used as low-pressure (LP) steam turbine materials, was investigated by electrochemical corrosion tests in the simulated boiler water contained chloride and sulfate ions. For 3.5NiCrMoV steel, by comparison with the surfaces outside crevice, the surfaces inside crevice of the specimens coupled with both of the same steel and 13Cr steel showed no remarkably corroded pattern even though pitting corrosion was observed. The specimen of 13Cr steel coupled with the same steel plate exhibited pitting corrosion inside the crevice, and a lower open cycle potential (Ocp) than the single plate of 13Cr steel. On the other hand, the specimen of 13Cr steel coupled with 3.5NiCrMoV steel plate showed the lowest Ocp, as the anodic dissolutions of 3.5NiCrMoV steel became the dominate corrosion mechanism.

Micro-Abrasion-Corrosion Mapping of Bio-Materials: Some New Perspectives

2005 ◽  
Author(s):  
M. M. Stack ◽  
J. Rodling ◽  
M. T. Mathew
Keyword(s):  
Interactive Effects ◽  
Corrosion Mechanism ◽  
Atomic Force ◽  
Recent Developments ◽  
Corrosion Mechanisms ◽  
Microscopy Techniques ◽  
Ultra High Molecular Weight ◽  
Electrochemical Potentials ◽  
Tribological Parameters

Recent developments in the studies of micro-abrasion have resulted in the construction of mechanistic maps where the change in micro-abrasion is presented as a function of the main tribological parameters. However, in many practical situations where micro-abrasion occurs, the environment tends to be corrosive. In such cases, the interaction of micro-abrasion and corrosion is of interest because the combined interaction may lead to “synergistic” or “antagonistic” effects, where corrosion may have a deleterious or beneficial effect in modifying the mechanical properties of the surface. In this paper, the micro-abrasion of a Co-Cr specimen against an ultra high molecular weight polyethylene (UHMWPE) ball was studied in Ringers solution. The effects of applied load at a range of electrochemical potentials were investigated. Atomic force and scanning electron microscopy techniques were used to identify the extent of wear and the role of the corrosion film on the micro-abrasion rate enabling the various wear, corrosion and the interactive effects to be evaluated for the system. The results showed that various micro-abrasion-corrosion mechanisms could be identified in active and passive conditions. These were used to generate micro-abrasion-corrosion mechanism maps showing the change in mechanism as functions of load and applied potential and the extent of interaction between the wear and the corrosion processes was demonstrated on such maps. Possible uses of the generic form of these maps to identify micro-abrasion-corrosion mechanisms in other bio-medical applications are addressed in this paper.

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