A new perspective on measuring the corrosion rate of localized corrosion

2020 ◽  
Vol 71 (5) ◽  
pp. 808-823 ◽  
Author(s):  
Ueli Angst ◽  
Markus Büchler
Keyword(s):  
Corrosion Rate ◽  
Localized Corrosion ◽  
New Perspective

The Calculation of the Thickness for Uniform Corrosion and Localized Corrosion in Steel Corrosion

2011 ◽  
Vol 255-260 ◽  
pp. 514-518
Author(s):  
Zheng Yi Kong ◽  
Shan Hua Xu ◽  
Yu Sheng Chen
Keyword(s):  
Corrosion Rate ◽  
Constant Temperature ◽  
Safety Assessment ◽  
Steel Corrosion ◽  
Localized Corrosion ◽  
Power Relationship ◽  
Uniform Corrosion ◽  
Experiment Data ◽  
Temperature And Humidity ◽  
Corrosion Pits

Because of the complexity of corrosion, the law of uniform corrosion and localized corrosion is still not clear,so it is difficult to assess their impact on the structure safety. In order to differ them and find their own law, we obtain a lot of corrosion specimens by ways of constant temperature and humidity, and then detect the size of corrosion pits by roughness tester. After that, the method for calculating the thickness of uniform corrosion and localized corrosion is proposed. Then the method is used to analyze the experiment data. The result indicates the thickness of uniform corrosion and localized corrosion all increase with the rate of corrosion, and they all show a power relationship with corrosion rate, so it will provide a basis for distinguishing them in safety assessment.

scholarly journals Application of Kelvin Probe Force Microscopy (KFM) to Evidence Localized Corrosion of Over-Aged Aeronautical 2024 Aluminum Alloy

2013 ◽  
Vol 550 ◽  
pp. 127-134
Author(s):  
Nicoleta Radutoiu ◽  
Joël Alexis ◽  
Loïc Lacroix ◽  
Marioara Abrudeanu ◽  
Jacques Alain Petit
Keyword(s):  
Aluminum Alloy ◽  
Corrosion Rate ◽  
Pitting Corrosion ◽  
Corrosion Damage ◽  
Localized Corrosion ◽  
Kelvin Probe ◽  
Force Microscopy ◽  
Intermetallic Particles ◽  
2024 Alloy ◽  
The Matrix

The 2xxx serie aluminum alloys are characterized by good mechanical performances and low density, however they are susceptible to different forms of localized corrosion: pitting corrosion, intergranular corrosion and stress corrosion cracking. The 2024-T351 aluminum alloy is used in the aircraft industry for numerous applications such as fuselage and door skin. Corrosion damage of the material is also very detrimental for the structural integrity of the aircraft. The presence of coarse intermetallic particles, with a heterogeneous size distribution was found to be responsible for the 2024 susceptibility to localized corrosion. These particles are generally the cause of initiation sites. Presence of micro-defects in the oxide film upon coarse intermetallic particles and the galvanic coupling with the matrix contribute to the development of pitting corrosion. The over-ageing treatment (T7) is supposed to stabilize the microstructure and the mechanical properties to improve the corrosion resistance. The 2024 alloy microstructure after the T7 heat treatment remains very complex. The 2024 alloy corrosion behavior was studied in the over-ageing state for three different temperatures (150, 175 and 190 °C). During the corrosion tests in chloride-containing environment, the behavior of coarse intermetallic particles was found to be different. Thus, the 2024 samples suffer a gradual attack upon S-Al2CuMg particles and finally Al (Cu,Mn,Fe,Si) particles. The corrosion damage was studied by Atomic Force Microscopy (AFM) and Kelvin probe Force Microscopy (KFM). This technique allows simultaneous topographical and electric potential mapping to be obtained. This latest potential was shown to be correlated to the corrosion potential of the 2024 alloy. This study focuses on the variation of the KFM potential of the coarse intermetallic particles and the matrix for the over-ageing conditions (T7). Observations using optical microscope and AFM were also performed to obtain the corrosion rate for each condition. The corrosion rate was correlated to the chemical composition variation of the particles obtained by scanning electron microscope observations and EDS analyses.

Localized Corrosion of 304 Stainless Steel under a NaCl Droplet

2011 ◽  
Vol 480-481 ◽  
pp. 443-447
Author(s):  
Yan Hua Wang ◽  
Yuan Yuan Liu
Keyword(s):  
Stainless Steel ◽  
Corrosion Rate ◽  
Corrosion Potential ◽  
Corrosion Process ◽  
Localized Corrosion ◽  
304 Stainless Steel ◽  
Galvanic Current ◽  
Cooperative Effects ◽  
Electrochemical Parameters ◽  
Wire Beam Electrode

The distributions of corrosion potential and galvanic current of 304 stainless steel under a NaCl droplet were studied by using the wire beam electrode (WBE). It was found that the distributions of the electrochemical parameters were heterogeneous with isolated anodic and cathodic zones appeared randomly. During the corrosion process, the polarity of some anodes changed with the evolution of time. The localized corrosion rate and heterogeneity increased firstly, and then decreased afterward with the increase of time, which can be attributed to the cooperative effects of the aggressive ions and the corrosion products.

Effect of pH on the Grain Size Dependence of Magnesium Corrosion

CORROSION ◽  
2012 ◽  
Vol 68 (6) ◽  
pp. 507-517 ◽  
Author(s):  
K. D. Ralston ◽  
G. Williams ◽  
N. Birbilis
Keyword(s):  
Grain Size ◽  
Corrosion Rate ◽  
Anodic Polarization ◽  
Localized Corrosion ◽  
Anodic Reaction ◽  
Left Behind ◽  
Kinetics Of ◽  
Electrode Technique

Prior works show that grain size can play a role in the corrosion of a metal; however, such works are nominally executed in a single electrolyte/environment at a single pH. In this work, the anodic and cathodic reaction kinetics of pure Mg specimens with grain sizes ranging from approximately 8 μm to 590 μm were compared as a function of pH in 0.1 mol dm−3 sodium chloride (NaCl) electrolytes using anodic polarization experiments and an in situ scanning vibrating electrode technique (SVET). Anodic polarization experiments showed that grain size is important in determining overall electrochemical response, but the environment dictates the form of the grain size vs. corrosion rate relationship (i.e., pH is the overall controlling factor). Consequently, the role of grain size upon corrosion cannot be fully assessed unless a variation in environment is simultaneously studied. For example, the anodic reaction, which dictates active corrosion, also dictates passivation, so the corrosion rate vs. grain size relationship has been shown to “flip” depending on pH. Further, SVET analysis of unpolarized Mg immersed in 0.1 mol dm−3 NaCl electrolyte at neutral pH showed that breakdown of passivity of cast Mg occurred after ~1 h immersion, giving filiform-like corrosion tracks. The front edges of these corrosion features were revealed as intense local anodes, while the remainder of the dark-corroded Mg surface, left behind as the anodes traversed the surface, became cathodically activated. In contrast, grain-refined Mg samples were significantly less susceptible to localized corrosion, and breakdown was not observed for immersion periods of up to 24 h.

Study of the Degradation Behaviour of Biomaterial Mg-4.0Zn-2.0Sr Alloy in SBF

2015 ◽  
Vol 1095 ◽  
pp. 309-313 ◽  
Author(s):  
Tong Cui ◽  
Ren Guo Guan ◽  
Hai Ming Qin ◽  
Fu Lin Song
Keyword(s):  
Corrosion Rate ◽  
Pitting Corrosion ◽  
Biological Properties ◽  
Alloy Sheet ◽  
Localized Corrosion ◽  
Cyclic Process ◽  
Degradation Behaviour ◽  
Corrosion Resistance Property ◽  
Corrosion Pitting ◽  
Average Corrosion Rate

In v itro degradation behaviour and biological properties of Mg-4.0Zn-2.0Sr alloy sheet had been studied. The results indicate that a novel biodegradable Mg-4.0Zn-2.0Sr (wt. %) alloy sheet was successfully produced using a series of metallurgical processes. The corrosion of Mg-4.0Zn-2.0Sr (wt. %) alloy sheet immersed in SBF occurred as a cyclic process: pitting corrosion →extending of pitting corrosion along grain boundary→ localized corrosion → pitting corrosion again at the new exposed surfaces and the corrosion products were found that contain HA, CaCO3 and MgOH. The change of corrosion rate of Mg-4.0Zn-2.0Sr alloy sheets immersed in SBF is unstable until the 17th day and the average corrosion rate of the alloy sheets was 1.244 g/(m2 • h) after 17 days immersing, which is slightly higher than that of Mg-4.0Zn-1.0Sr alloy sheet 1.163 g/(m2 • h). The corrosion resistance property in SBF of Mg-4.0Zn-2.0Sr alloy is slightly lower than that of Mg-4.0Zn-1.0Sr alloy, which is proved by electrochemical measurements.

scholarly journals Corrosion Behavior of 3% Cr Casing Steel in CO2-Containing Environment: A Case Study

2018 ◽  
Vol 11 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Lin Xu ◽  
Jie Xu ◽  
Ming-biao Xu ◽  
Si-yang Li ◽  
Shuai Liu ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Corrosion Product ◽  
Corrosion Behavior ◽  
Exposure Time ◽  
Corrosion Products ◽  
Localized Corrosion ◽  
Internal Corrosion ◽  
Tafel Polarization ◽  
Water Cut ◽  
Increasing Temperature

Introduction: The production casing of 3% Cr steel has encountered severe internal corrosion in Huizhou Oilfield. To disclose corrosion behavior of inner casing, a series of corrosion exposure tests were systematically conducted on 3% Cr coupons in terms of in-field conditions. Material and Methods: Influence of exposure time, temperature, and water-cut on the CO2 corrosion of 3% Cr steel was investigated, and analyses on weight loss, composition and morphology of corrosion product, and Tafel polarization curves were further carried out. Result: The results showed that the corrosion rate of 3% Cr steel increased with increasing temperature, but such trend descended when the temperature exceeded 65°C due to formation of an compact and adherent corrosion product film on the surface of 3% Cr coupons. While varying exposure time from 7 days to 14 days, the corrosion rate decreased, and the Cr and O enrichment was determined in the corrosion products. The corrosion rate of 3% Cr steel increased with a continuous increment of water-cuts, especially when the water-cut was larger than 40%. Conclusion: The localized corrosion can happen at the lower water-cut due to the presence of amorphous films. The main corrosion products were FeCO3, Cr5O12, Fe2O3, and Fe-Cr. Entry of CO2 to the simulated formation water caused an increase in the anodic Tafel slope, and accelerated dissolution of 3% Cr steel.

Effect of nitrate and chromate on the localized corrosion of iron and nickel

1981 ◽  
Vol 46 (11) ◽  
pp. 2834-2841 ◽  
Author(s):  
Jaromír Toušek
Keyword(s):  
Activation Energy ◽  
Corrosion Rate ◽  
Competitive Adsorption ◽  
Localized Corrosion ◽  
Favourable Effect ◽  
Water Molecules ◽  
Metal Dissolution ◽  
Breakdown Potential ◽  
Passivation Potential ◽  
Corrosion Of Iron

The combined effect of some inorganic inhibitors - chromate and nitrate - on the rate of localized corrosion of iron and nickel was investigated. The efficiency of these inhibitors and the mechanism of their effect were found to depend on the potential. If the breakdown potential is lower than the second passivation potential, the corrosion rate decreases owing to the competitive adsorption of inhibitor and of aggresive ions and owing to a change in the activation energy of the metal dissolution. Substances that are strongly adsorbed on the electrode act in this region as strong inhibitors. In the range of the second passivation potential there operates another mechanism consisting in a favourable effect of the water molecules in the inhibitor hydration sphere on the rate of the passivation reaction. In this range, even such substances that are only weakly adsorbed on the electrode can act as strong inhibitors.

scholarly journals New perspective on Jun glaze corrosion: study on the corrosion of light greenish blue and reddish purple glazes from Juntai Kiln, Yuzhou, Henan, China

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Zhimin Li ◽  
Ying Ma ◽  
Qinglin Ma ◽  
Jiachang Chen ◽  
Yan Song
Keyword(s):  
Calcium Ions ◽  
Coming Out ◽  
Active Sites ◽  
Dissolved Inorganic Carbon ◽  
Structural Features ◽  
Localized Corrosion ◽  
Corrosion Mechanism ◽  
Greenish Blue ◽  
New Perspective ◽  
The Ancient Chinese

AbstractThe ancient Chinese Jun Porcelain has of typical high fired calcium silicate glaze. After observation of Jun porcelain shards excavated from Juntai Kiln in Yuzhou, Henan Province, China, two pieces with light greenish blue glaze and reddish purple glaze are selected for study as special corrosion samples buried in soil environment. Taking the corrosion of each phase of the overall glaze into consideration, the chemistry compositional and morphological structural features of the earthworm-walking patterns and their surrounding white area (corroded zone) in the glazes are compared and studied with optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray analysis (SEM–EDS), Raman spectroscopy (Raman) and electron microprobe (EPMA): during the firing of Jun Porcelain, the dendritic and columnar crystals coming out of the glaze and mostly in surrounding corroded areas are identified as wollastonite (CaSiO3), which provides active sites for localized corrosion. The wollastonite crystalline phases have preferential corrosion initiated by pitting corrosion relative to glassy phase, leaving dendritic or columnar pits and craters to dissolve into calcium ions and silicic acid and losing into the burial environment. Some calcium ions in the surface pits react with dissolved inorganic carbon (DIC) from the soil to form calcium carbonate (CaCO3) precipitated on the surface of the glazes. The cracks formed during the cooling process and the interconnected craters caused by crystals dissolution can provide channels to facilitate the progression of the corrosion. This research is of great significance to the study of the corrosion mechanism of ancient porcelain and the conservation of its cultural relics. It has changed the traditional view that porcelain is corrosion-resistant. At the same time, the study of the corrosion process and characteristics of ancient porcelain can provide reference for modern ceramic research and corrosion protection.

Electrochemical Investigation of Under-Deposit Corrosion Behavior for Aluminum Brass in Artificial Seawater

CORROSION ◽  
10.5006/3428 ◽  
2020 ◽  
Vol 76 (11) ◽  
pp. 1050-1063
Author(s):  
Hong Ju ◽  
Weihui Xu ◽  
Jiejing Chen ◽  
Dalei Zhang ◽  
Guomin Liu ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Electrochemical Impedance ◽  
Electrolytic Cell ◽  
Artificial Seawater ◽  
Localized Corrosion ◽  
Effect Of Temperature ◽  
Multielectrode Arrays ◽  
Energy Dispersive Spectrometry Analysis ◽  
Spectrometry Analysis

The under-deposit corrosion behavior and mechanism of aluminum brass (HAl77-2) were investigated in artificial seawater with a custom double electrolytic cell. The experiments included linear polarization, electrochemical impedance spectroscopy, and multielectrode arrays analysis. The electrochemical results revealed a pronounced effect of temperature on the under-deposit corrosion behavior of HAl77-2. The corrosion of HAl77-2 inside the CaCO3 scale is aggravated with increasing temperature. However, the increasing frequency of the corrosion rate of HAl77-2 gradually decreased after 333 K. Moreover, in the desalination of artificial seawater, the corrosion rate of HAl77-2 in the occulated area initially increased and subsequently decreased with increasing Cl− concentration. The scanning electron microscopy and energy dispersive spectrometry analysis showed a remarkable appearance of selective localized corrosion on the surface of HAl77-2.

Corrosion study of low carbon steel under simulated geological disposal environments for HLW in China

2020 ◽  
Author(s):  
Junhua Dong
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Dissolved Oxygen ◽  
Open Circuit Potential ◽  
Steel Substrate ◽  
Low Carbon Steel ◽  
Open Circuit ◽  
Localized Corrosion ◽  
Low Carbon ◽  
Simulated Groundwater

<p>In the multi-barrier system of HLW repository, overpack is the first barrier to isolate high-level radioactive nuclides from biosphere, and Low carbon steel has been considered to be a promising candidate material for manufacturing the oberpack due to its good mechanical performance and workability and weldability. However, during thousands of years of geological disposal, the corrosion resistance of low carbon steel and its corrosion evolution behavior are the first element that must be fully understood, because it determines the life cycle of the artificial barrier.</p><p>Conventional studies had suggested that the corrosion of low carbon steel under the deep geological environment was driven by hydrogen evolution reaction (HER) based on that the dissolved oxygen was completely depleted during the long term disposal. However, the residual oxygen content is a critical factor to determine the corrosion mode of cathodic reduction reaction. Thermodynamics data indicated that the initial ferrous corrosion products formed in the deaerated bicarbonate solution can be chemically oxidized into ferric substance by the trace content of dissolved oxygen, and the accumulated FeOOH as a cathodic depolarizer significantly increased the open circuit potential and enhanced the corrosion rate of the low carbon steel. Moreover, chloride and sulfate in the simulated groundwater can reduce the increase of open circuit potential but it still promotes the corrosion of the low carbon steel. As the environments contained aggressive anions and high concentration of dissolved oxygen, low carbon steel was prone to suffer from the localized corrosion and the corrosion rate was obviously increased. By alloying with some contents of Ni and Cu, the corrosion rate of low alloy steel was decreased by an order of magnitude and it was less prone to suffer from the localized corrosion.</p><p>Under the conditions of simulated groundwater with different content of GMZ bentonite，the bentonite colloidal particle layer attached to the surface of low carbon steel showed blocking effect on resisting oxygen diffusion to the steel substrate, which consequently decrease the further oxidation of ferrous to ferric substances and the corrosion rate of low carbon steel. However, the barrier performance of bentonite colloids would be deteriorated due to their coagulation caused by the ferrous ions dissolved from the steel substrate. High content of bentonite was beneficial to maintain and to prolong the stabilization of the barrier system. An equivalent circuit model which correlates with the interfacial structure between electrode substrate and rust and bentonite layer was proposed. The fitting results showed a very good match between the model and experimental data, and the evolution of the results was also in agreement with real changes.</p>

Sign in / Sign up

Export Citation Format

Share Document