Corrosion Initiation and Anodic-Cathodic Alternation of Localized Corrosion of SiC-Reinforced Aluminum Composites in NaCl Solution

2019 ◽  
Vol 3 (31) ◽  
pp. 237-247 ◽  
Author(s):  
Hongbo Ding ◽  
Lloyd H. Hihara
Keyword(s):  
Localized Corrosion ◽  
Nacl Solution ◽  
Aluminum Composites ◽  
Corrosion Initiation

Radial Spreading of Localized Corrosion-Induced Selective Leaching on α-Brass in Dilute NaCl Solution

CORROSION ◽  
10.5006/0611 ◽  
2013 ◽  
Vol 69 (5) ◽  
pp. 468-476 ◽  
Author(s):  
Mattias Forslund ◽  
Christofer Leygraf ◽  
Changjian Lin ◽  
Jinshan Pan
Keyword(s):  
Localized Corrosion ◽  
Selective Leaching ◽  
Nacl Solution ◽  
Radial Spreading

scholarly journals Assessment of nickel titanium and beta titanium corrosion resistance behavior in fluoride and chloride environments

2013 ◽  
Vol 83 (5) ◽  
pp. 864-869 ◽  
Author(s):  
Elisa J. Kassab ◽  
José Ponciano Gomes
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Fluoride Concentration ◽  
Nickel Titanium ◽  
Localized Corrosion ◽  
General Corrosion ◽  
Nacl Solution ◽  
Galvanic Coupling ◽  
Beta Titanium

ABSTRACT Objective: To assess the influence of fluoride concentration on the corrosion behavior of nickel titanium (NiTi) superelastic wire and to compare the corrosion resistance of NiTi with that of beta titanium alloy in physiological solution with and without addition of fluoride. Materials and Methods: NiTi corrosion resistance was investigated through electrochemical impedance spectroscopy and anodic polarization in sodium chloride (NaCl 0.15 M) with and without addition of 0.02 M sodium fluoride (NaF), and the results were compared with those associated with beta titanium. The influence of fluoride concentration on NiTi corrosion behavior was assessed in NaCl (0.15 M) with and without 0.02, 0.04, 0.05, 0.07, and 0.12 M NaF solution. Galvanic corrosion between NiTi and beta titanium were investigated. All samples were characterized by scanning electron microscopy. Results: Polarization resistance decreased when NaF concentration was increased, and, depending on NaF concentration, NiTi can suffer localized or generalized corrosion. In NaCl solution with 0.02 M NaF, NiTi suffer localized corrosion, while beta titanium alloys remained passive. Current values near zero were observed by galvanic coupling of NiTi and beta titanium. Conclusions: There is a decrease in NiTi corrosion resistance in the presence of fluoride. The corrosion behavior of NiTi alloy depends on fluoride concentration. When 0.02 and 0.04 M of NaF were added to the NaCl solution, NiTi presented localized corrosion. When NaF concentration increased to 0.05, 0.07, and 0.12 M, the alloy presented general corrosion. NiTi corrosion resistance behavior is lower than that of beta titanium. Galvanic coupling of these alloys does not increase corrosion rates.

EIS Study on the Deterioration Process of Organic Coatings under Immersion and Different Cyclic Wet-Dry Ratios

2012 ◽  
Vol 161 ◽  
pp. 58-66 ◽  
Author(s):  
Wei Zhang ◽  
Xue Zheng Chen ◽  
Peng Fei Yin ◽  
Zheng Kai Xu ◽  
Bing Han ◽  
...  
Keyword(s):  
Electrochemical Techniques ◽  
Organic Coating ◽  
Organic Coatings ◽  
Metal Corrosion ◽  
Nacl Solution ◽  
Corrosion Initiation ◽  
Carbon Steel Surface ◽  
Short Period ◽  
Deterioration Process ◽  
Immersion Condition

Under immersed and we-dry cyclic conditions, the deterioration processes of the organic coating on carbon steel surface have been comparatively studied using electrochemical techniques. The wet-dry cycles were carried out by exposure to 4 h immersion and 4h dryness (4-4h cycles) and 12h immersion and 12h dryness (12-12h cycles) conditions, respectively. The immersion condition was carry out in a 3.5% NaCl solution and drying at 298K and 50% RH. According to the EIS characteristics, the entire deterioration processes under above three mentioned conditions can be divided into three main stages, consisting of the medium penetration, corrosion initiation and corrosion extension. Comparing with the immersed, the 4-4h wet-dry cycles greatly accelerated the entire deterioration process; especially during the corrosion initiation and the corrosion extension periods, leading the paint system lose its anti-corrosive performance in a short period. However, the 12-12h wet-dry cycles decelerated the entire deterioration process, prolonging the coatings anticorrosive ability. The acceleration mechanism of the coatings and underlying metal corrosion under wet-dry cycles was discussed based on the above results.

scholarly journals Effects of LaAlO3 and La2O2S inclusions on the initialization of localized corrosion of pipeline steels in NaCl solution

2020 ◽  
Vol 177 ◽  
pp. 151-156 ◽  
Author(s):  
Yanhui Hou ◽  
Gang Xiong ◽  
Linli Liu ◽  
Guangqiang Li ◽  
Nele Moelans ◽  
...  
Keyword(s):  
Localized Corrosion ◽  
Nacl Solution ◽  
Pipeline Steels

Influence of transverse crack width on reinforcement corrosion initiation and propagation in mortar beams

2008 ◽  
Vol 35 (3) ◽  
pp. 236-245 ◽  
Author(s):  
Mustafa Şahmaran ◽  
İ. Özgür Yaman
Keyword(s):  
Diffusion Coefficient ◽  
Effective Diffusion Coefficient ◽  
Crack Width ◽  
Effective Diffusion ◽  
Reinforcing Bars ◽  
Nacl Solution ◽  
Accelerated Corrosion ◽  
Corrosion Initiation ◽  
Initiation And Propagation ◽  
Crack Widths

This paper discusses the relationship between crack widths, chloride diffusivity, and corrosion rate of cracked mortar beams. Flexural loads are introduced to generate crack widths ranging from 29 to 390 µm. The specimens were subjected to accelerated corrosion by immersion in a 5% NaCl solution and a constant voltage of 12 V. In addition, salt ponding tests were conducted to determine the chloride ion transport properties. The results showed that as the crack width increased, the effective diffusion coefficient (corrosion initiation) and mass loss of steel reinforcing bars due to the accelerated corrosion (corrosion propagation) also increased. For crack widths less than about 135 µm, the effect of crack width on the effective diffusion coefficient and mass loss of steel reinforcing bars embedded in mortar specimens was found to be marginal when compared with the virgin specimens. Therefore, it was concluded that the effect of crack width on the corrosion initiation and propagation period was more pronounced when the crack width is greater than about 135 µm. Moreover, a significant amount of self-healing was observed for the cracks that have widths below 50 µm when subjected to the NaCl solution exposure.

Corrosion of High Zn Content Al-Zn-Mg-Cu Alloy in 3.5 wt.% NaCl Solution

2014 ◽  
Vol 703 ◽  
pp. 21-28
Author(s):  
Fan Qing Ran ◽  
Zi Yong Chen ◽  
Li Hua Chai
Keyword(s):  
Corrosion Process ◽  
Localized Corrosion ◽  
Nacl Solution ◽  
X Ray ◽  
Second Stage ◽  
Cu Alloy ◽  
Zn Content ◽  
The Matrix ◽  
Two Stages ◽  
Scanning Electron

In this paper, the polished specimens of high Zn content Al-Zn-Mg-Cu alloy after various aging treatments were immersed in 3.5 wt.% NaCl for up to 240 mins. The development of corrosion was monitored using scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). There are two stages during the corrosion process, the first stage of attack started with localized corrosion of trenching around the Al-Zn-Mg-Cu particles. In the second stage the pitting corrosion appeared at the grain boundaries, and then developed into intergranular corrosion. This phenomenon is related to the potential difference between the matrix and the precipitates.

scholarly journals Effect of Microstructure on the Localized Corrosion and Stress Corrosion Behaviours of Plasma-Electrolytic-Oxidation-Treated AA7075 Aluminum Alloy Forging in 3.5 wt. %NaCl Solution

2012 ◽  
Vol 2012 ◽  
pp. 1-8 ◽  
Author(s):  
A. Venugopal ◽  
Rajiv Panda ◽  
Sushant Manwatkar ◽  
K. Sreekumar ◽  
L. Ramakrishna ◽  
...  
Keyword(s):  
Stress Corrosion ◽  
Plasma Electrolytic Oxidation ◽  
Tensile Tests ◽  
Localized Corrosion ◽  
Nacl Solution ◽  
Uncoated Sample ◽  
Electrolytic Oxidation ◽  
Metallographic Observation ◽  
The One ◽  
Plasma Electrolytic

The influence of metallurgical heterogeneities such as coring and intermetallic phases on the corrosion and stress corrosion cracking behaviours of AA7075 aluminium alloy forging was examined in 3.5 wt. % NaCl solution with and without plasma electrolytic oxidation coating. Electrochemical test results demonstrated significant improvement in the corrosion resistance of the alloy after PEO coating. Stress corrosion results show that the metallurgical heterogeneities resulted in a loss in elongation of the uncoated sample in NaCl (11.5%) when compared to the one tested in air (12.9%). The loss in elongation of the uncoated sample was shown to be due to localized corrosion-assisted mechanical cracking rather than true stress corrosion based on preexposure tensile tests followed by posttest metallographic observation of the stress corrosion tested samples. This was further confirmed by the fractographic examination of the failed samples, which exhibited a typical ductile cracking morphology for all the coated and uncoated specimens.

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