Aluminium corrosion studies. II. Corrosion rates in water

1977 ◽  
Vol 30 (4) ◽  
pp. 721 ◽  
Author(s):  
A Berzins ◽  
JV Evans ◽  
RT Lowson
Keyword(s):  
Corrosion Rate ◽  
Dissolved Oxygen ◽  
Chloride Concentration ◽  
Chloride Ions ◽  
Oxide Surface ◽  
Corrosion Rates ◽  
Saturated Water ◽  
Corrosion Studies ◽  
Competitive Action ◽  
Ph Range

The corrosion rate of aluminium in flowing neutral waters at 50�C has been determined as a function of pH, oxygen concentration and chloride concentration. The corrosion rate, At, as total aluminium lost between the 4th and 80th day was observed to be logarithmic according to At = B log t+C with a minimum rate in the pH range 5-6, and with B c. 3 x 10-5g cm2, C c. 20 x 10-5 g cm-2 and t in days for oxygen-saturated water. Saturating the water with nitrogen or adding up to 15 mg Cl- l-1 increased the corrosion rate. It was concluded that this was due to competitive action on the oxide surface, between dissolved oxygen and chloride ions.

Steel Corrosion Patterns in Neutral and Alkaline Iron Oxide Slurry

2021 ◽  
pp. 142-155
Author(s):  
V.A. Shelontsev ◽  
I.G. Gorichev ◽  
A.V. Kuzin ◽  
I.V. Gerasimova ◽  
E.A. Eliseeva
Keyword(s):  
Iron Oxide ◽  
Corrosion Rate ◽  
Dissolved Oxygen ◽  
Polarization Resistance ◽  
Gravimetric Method ◽  
Sharp Decrease ◽  
Steel Corrosion ◽  
Chloride Ions ◽  
Diffusion Control ◽  
Ph Range

The study identifies and theoretically substantiates the steel corrosion patterns in aqueous slurry of iron-ore concentrate. The purpose of the study was to examine the effect that the content of dissolved oxygen(PO2), pH, the concentration of chloride ions (CCl-) and the rate of movement of the iron oxide slurry (ω) produce on the corrosion losses of steel 20. Comparative analysis of the corrosion rate values obtained by the gravimetric method and the polarization resistance method showed that the reciprocal of the polarization resistance and the corrosion rate change symbatically with increasing pH, the corrosion rate values are quantitatively well consistent with each other. To identify the corrosion patterns, the method of polarization resistance was used. The dependence of the corrosion rate (ρ) on рН revealed two characteristic areas: in the first one, there is no dependence of the rate on pH (6.5--9.0); in the second one, there is a sharp decrease in corrosion losses when the pH goes from 9.0 to 12.5. For pH = 6.5--9.0, the corrosion rate increases linearly with an increase in the partial pressure of oxygen, and corrosion losses in the slurry are higher than in the background solution. The dependence ρ(√ω) is linear over the entire pH range (6.0--9.0), which indicates the diffusion control of the corrosion process. Findings of research show that in order to protect carbon steel from corrosion in the iron oxide slurry, it is necessary to take into account the pH and О2 concentration. Optimal reduction of corrosion losses can be achieved by alkalizing the slurry and removing dissolved oxygen

scholarly journals Effect of Fe, Ni, and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy under different pH conditions

2018 ◽  
Vol 8 (3) ◽  
pp. 241-253
Author(s):  
Mohammad Salim Kaiser ◽  
Maglub Al Nur
Keyword(s):  
Corrosion Rate ◽  
Oxide Film ◽  
Corrosion Behaviour ◽  
Chloride Ions ◽  
Surface Oxide ◽  
Surface Oxide Film ◽  
Sem Images ◽  
Optical Micrograph ◽  
Ph Conditions ◽  
Ph Range

Effect of Fe, Ni and Cr on the corrosion behaviour of hyper-eutectic Al-Si automotive alloy was studied. The test of corrosion behaviour at different environmental pH 1, 3, 5, 7, 9, 11 and 13 was performed using conventional gravimetric measurements and complemented by resistivity, optical micrograph, scanning electron microscopy (SEM) and X-ray analyser (EDX) investigations. The highest corrosion rate was observed at pH 13 followed by pH 1, while in the pH range of 3.0 to 11, there is a high protection of surface due to formation of stable surface oxide film. The highest corrosion rate at pH 13 is due to presence of sodium hydroxide in the solution in which the surface oxide film is soluble. At pH 1, however, high corrosion rate can be attributed to dissolution of Al due to the surface attack by aggressive chloride ions. Presence of Fe, Ni and Cr in hyper-eutectic Al-Si automotive alloy has significant effect on the corrosion rate at both environmental pH values. Resistivity of alloy surfaces initially decreases at pH 1 and pH 13 due to formation of thin films. The SEM images of corroded samples immersed in pH 1 solution clearly show pores due to uniform degradation of the alloy. In pH 13 solution, however, the corrosion layer looks more packed and impermeable.

An Innovative Specimen for Mg Corrosion Studies

2011 ◽  
Vol 690 ◽  
pp. 365-368 ◽  
Author(s):  
Zhi Ming Shi ◽  
Andrej Atrens
Keyword(s):  
Weight Loss ◽  
Corrosion Rate ◽  
High Purity ◽  
Crevice Corrosion ◽  
Corrosion Current Density ◽  
Cathodic Polarization ◽  
Corrosion Current ◽  
Polarization Curves ◽  
Corrosion Rates ◽  
Corrosion Studies

Plug-in specimens enable measurement of reliable Mg polarization curves. Cathodic polarization curves were measured for high purity Mg in 3.5% NaCl saturated with Mg(OH)2using (i) mounted specimens and (ii) plug-in specimens. Polarization curves yielded the corrosion current densityicorrand the corresponding corrosion ratePi, which was compared with corrosion rates evaluated from hydrogen evolution,PH, and weight loss,PW. Mounted specimens producePivalues three times larger than plug-in specimens, due to crevice corrosion in the mounted specimens. Plug-in specimens had no crevice and allow simultaneous measurement ofPHandPi. Piwas less thanPHand indicated an apparent valence of 1.45 in support of the existence of the uni-positive Mg+ion.

The Effect of Dissolved Oxygen on Corrosion of Steel And on Current Required for Cathodic Protection★

CORROSION ◽  
1957 ◽  
Vol 13 (4) ◽  
pp. 35-43 ◽  
Author(s):  
E. SCHASCHL ◽  
G. A. MARSH
Keyword(s):  
Corrosion Rate ◽  
Dissolved Oxygen ◽  
Current Density ◽  
Cathodic Protection ◽  
Dissolved Oxygen Concentration ◽  
Anodic Reaction ◽  
Corrosion Rates ◽  
Acidic Environments ◽  
Corrosion Of Steel ◽  
Very High

Abstract The interrelationship of corrosion rate of steel, dissolved oxygen concentration, agitation, electrode potential, and cathodic protection current density were studied under controlled laboratory conditions. While the corrosion rate of steel is essentially linear with amount of dissolved oxygen, the rate appears to fall almost to zero near 1.0 ppm dissolved oxygen rather than at zero ppm dissolved oxygen as commonly assumed. In the region below 2 ppm dissolved oxygen, there is almost no effect of agitation on corrosion rate; above 2 ppm there is a large effect. By measuring the corrosion rate of an unprotected specimen, it should be possible to compute the minimum current density needed for cathodic protection in the field. In acidic environments, less current is needed for protection than is predicted by analysis of the mechanism of cathodic protection. This fact suggests that the anodic reaction in low pH corrosion proceeds by the removal of “chunks” of metal which contain several atoms. The “chunk effect” also appears to operate in the neutral range, but only when the corrosion rate is very high. The effect of differential aeration on corrosion rates is discussed in detail. 5.2.4

Monitoring corrosion rate for ordinary portland concrete (OPC) and high-performance concrete (HPC) specimens subjected to chloride attack

2002 ◽  
Vol 29 (6) ◽  
pp. 863-874 ◽  
Author(s):  
Mohamed E Ismail ◽  
Hamid R Soleymani
Keyword(s):  
Corrosion Rate ◽  
High Performance ◽  
High Performance Concrete ◽  
Chloride Concentration ◽  
Electrochemical Technique ◽  
Reinforcing Steel ◽  
Destructive Testing ◽  
Corrosion Rates ◽  
Chloride Attack ◽  
American Society

This paper presents the results and the applicability of an electrochemical technique, the Tafel plot method, for determining the corrosion rate of reinforcing steel embedded in laboratory ordinary portland concrete (OPC) and high-performance concrete (HPC) specimens. Fifty-two OPC and 52 HPC concrete cylinders, each with a single embedded reinforcing steel rod, have been subjected to various laboratory conditions, and the corrosion rate of each specimen has been monitored. Results indicate that HPC specimens performed much better than OPC specimens in terms of resisting corrosion, as the corrosion rates were far lower for the HPC specimens than for the OPC specimens. Sodium chloride concentration played an important role in the propagation of corrosion: the higher the NaCl concentration, the higher the corrosion rate. In addition, different cycles of wetting and drying of concrete specimens had different impacts on corrosion rates. Results for the chloride concentration based on the American Society for Testing and Materials (ASTM) destructive testing method C1218 were in agreement with the corrosion rate results from the Tafel plot method used in the study.Key words: corrosion, electrochemical, reinforced concrete, Tafel method, high-performance concrete.

Corrosion Behavior of X70 Pipeline Steel and Corrosion Rate Prediction Under the Combination of Corrosive Medium and Applied Pressure

2017 ◽  
Author(s):  
Kaikai Li ◽  
Wei Wu ◽  
Guangxu Cheng ◽  
Yun Li ◽  
Haijun Hu ◽  
...  
Keyword(s):  
Natural Gas ◽  
Corrosion Rate ◽  
Tensile Stress ◽  
Partial Pressure ◽  
Corrosion Behavior ◽  
Pipeline Steel ◽  
Applied Pressure ◽  
Chloride Concentration ◽  
X70 Pipeline Steel ◽  
Co2 Partial Pressure

Natural gas transmission pipeline is prone to internal corrosion due to the combination of corrosive impurities in the pipe (such as CO2, H2S and chlorides) and applied pressure of the pipeline, which seriously affects the safe operation of the pipeline. In this work, the corrosion behavior of a typical X70 pipeline steel was investigated by using potentiodynamic polarization and electrochemical impendence spectroscopy (EIS). The polarization and EIS data under different CO2 partial pressures (0–1 atm), H2S concentrations (0–150 ppm), chloride concentrations (0–3.5 wt%) and tensile stress (0–400 MPa) were obtained. The results show that corrosion rate increases with the increase of CO2 partial pressure and chloride concentration, respectively, while first increases and then decreases with the increase H2S concentrations. The corrosion rate is less affected by elastic tensile stress. In addition, a quantitative prediction model for corrosion rate of natural gas pipeline based on adaptive neuro-fuzzy inference system (ANFIS) was established by fitting the experimental data which maps the relationship between the key influencing factors (i.e. CO2 partial pressure, H2S concentration, chloride concentration and tensile stress) and the corrosion rate. The prediction results show that the relative percentage errors of the predicted and experimental values are relatively small. The prediction accuracy of the model satisfies the engineering application requirement.

Physical and Chemical Deterioration of Reinforced Concrete Reefs in Tongyeong Reefs Coastal Waters, Korea

2008 ◽  
Vol 42 (3) ◽  
pp. 110-118 ◽  
Author(s):  
H. S. Kim ◽  
C. G. Kim ◽  
W. B. Na ◽  
J. Woo ◽  
J. K. Kim
Keyword(s):  
Reinforced Concrete ◽  
Service Life ◽  
Dissolved Oxygen ◽  
Extreme Event ◽  
Chemical Properties ◽  
Chloride Concentration ◽  
Concrete Cover ◽  
Marine Habitat ◽  
Seawater Salinity ◽  
Physical And Chemical

As part of a marine habitat enhancement project, the physical and chemical deterioration of reinforced concrete reefs that were fully immersed in Tongyeong waters of Korea was investigated. For the investigation, marine environmental factors such as seawater, salinity, pH, dissolved oxygen, sea-bottom materials, and water depth of the targeted sites were surveyed from 1997 to 2001. Then, four reinforced concrete reefs from four different sites were recovered and tested by using various destructive and nondestructive methods. Based on the observations and test results, it was seen that the reinforced concrete reefs have sound physical and chemical properties, except for chloride concentration and its associated factors. However, because of the lack of dissolved oxygen in the targeted seawaters and its continuous supply, it is concluded that the originally designed service life will be achieved, and in fact the concrete reefs will have an even longer service life than expected. By considering an extreme event such as impact loading under installation and construction, a new minimum concrete cover depth of 40 mm is introduced into practice.

scholarly journals Application of Novel Machine Learning Techniques for Predicting the Surface Chloride Concentration in Concrete Containing Waste Material

Materials ◽  
2021 ◽  
Vol 14 (9) ◽  
pp. 2297
Author(s):  
Ayaz Ahmad ◽  
Furqan Farooq ◽  
Krzysztof Adam Ostrowski ◽  
Klaudia Śliwa-Wieczorek ◽  
Slawomir Czarnecki
Keyword(s):  
Machine Learning ◽  
Mean Square Error ◽  
Gene Expression Programming ◽  
Chloride Concentration ◽  
Absolute Error ◽  
Chloride Ions ◽  
Machine Learning Techniques ◽  
Extensive Literature ◽  
Mean Square ◽  
Chloride Concentrations

Structures located on the coast are subjected to the long-term influence of chloride ions, which cause the corrosion of steel reinforcements in concrete elements. This corrosion severely affects the performance of the elements and may shorten the lifespan of an entire structure. Even though experimental activities in laboratories might be a solution, they may also be problematic due to time and costs. Thus, the application of individual machine learning (ML) techniques has been investigated to predict surface chloride concentrations (Cc) in marine structures. For this purpose, the values of Cc in tidal, splash, and submerged zones were collected from an extensive literature survey and incorporated into the article. Gene expression programming (GEP), the decision tree (DT), and an artificial neural network (ANN) were used to predict the surface chloride concentrations, and the most accurate algorithm was then selected. The GEP model was the most accurate when compared to ANN and DT, which was confirmed by the high accuracy level of the K-fold cross-validation and linear correlation coefficient (R2), mean absolute error (MAE), mean square error (MSE), and root mean square error (RMSE) parameters. As is shown in the article, the proposed method is an effective and accurate way to predict the surface chloride concentration without the inconveniences of laboratory tests.

Competitive Chloride Chemisorption Disrupts Hydrogen Bonding Networks: DFT, Crystallography, Thermodynamics, and Morphological Consequences

CORROSION ◽  
10.5006/2555 ◽  
2017 ◽  
Vol 74 (3) ◽  
pp. 295-311 ◽  
Author(s):  
Laurence Marks
Keyword(s):  
Hydrogen Bonding ◽  
Surface Science ◽  
Density Functional ◽  
Chloride Ions ◽  
Oxide Surface ◽  
Aqueous Environment ◽  
Aqueous Corrosion ◽  
Function Change ◽  
Competing Models ◽  
Galvanic Couples

The consequence for aqueous corrosion of chloride ions in an aqueous environment on the surface structure and thermodynamics of hydroxylated magnesia (001) and alpha-alumina (001) and (100) is analyzed using density functional methods. It is shown that there is competitive chemisorption between hydroxide and chloride, with the chloride disrupting the hydrogen bonding network on the surface. There is a significant crystallographic dependence, as well as dependencies upon the environment in terms of the pH and chloride molarity. An analysis of the results in terms of existing, competing models in the literature for the effect of chloride indicates that rather than the existing models being competitors, most are correct but incomplete. Rather than the different models being viewed as competitors, or each being rate determining for some specific set of conditions, the majority are simultaneously correct. Conventional oxide surface science extrapolation of the results yields qualitative conclusions for the effects of, for instance, alloy dopants which are consistent with existing experimental data. The analysis also indicates the existence of a number of new phenomena in corrosion, for instance local galvanic couples due to the work-function change with chloride chemisorption, as well as thermodynamic dewetting of the oxide film.

Molecular Dynamics Study of the Interaction of C-S-H and Chloride Ions

2016 ◽  
Vol 711 ◽  
pp. 1061-1068
Author(s):  
Yang Zhou ◽  
Guo Dong Xu
Keyword(s):  
Molecular Dynamics ◽  
Calcium Silicate Hydrate ◽  
Chloride Concentration ◽  
Sorption Isotherms ◽  
Hydration Product ◽  
Chloride Ions ◽  
Dynamics Modeling ◽  
Solution Interface ◽  
Molecular Dynamics Modeling ◽  
Cement Based Materials

Molecular Dynamics was employed to investigate the interaction of calcium silicate hydrate (C-S-H), the primary hydration product of cement based materials, and chloride, causing severe durable problems of concrete. The 11Å tobermorite structure was chosen to describe the C-S-H structure and the CLAYFF force field was used. It is observed in the simulation that there are no bound chlorides at 303K, while a fraction of chlorides appear in the adsorption district of tobermorite/solution interface at 323K indicating the temperature increase can improve chloride sorption capacity of C-S-H. The formation of Ca-Cl cluster is found on the surface of tobermorite, which is assumed to promote the chloride sorption. The experimental results of sorption isotherms of C-S-H in CaCl2 and NaCl aqueous solutions with the same chloride concentration have proved this point. Other researchers have made the same conclusion by means of molecular dynamics modeling, NMR tests or zeta potential experiments.

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