Effect of Halide Anions on Anodic Behaviour and Passivation of Copper in Alkaline Media

1996 ◽  
Vol 61 (1) ◽  
pp. 85-92 ◽  
Author(s):  
Sayed S. Abd El Rehim ◽  
Essam E. Foad
Keyword(s):  
Pitting Corrosion ◽  
Passive Layer ◽  
Alkaline Media ◽  
Anode Surface ◽  
Alkali Concentration ◽  
Halide Anions ◽  
Instantaneous Nucleation ◽  
Cyclic Voltammetric Curve ◽  
Naoh Solution ◽  
Anodic Behaviour

The effect of Cl- and Br- on the anodic behaviour and passivation of copper metal in NaOH solution has been investigated by a potentiodynamic technique complemented with XPS analysis. In halide free solutions, the anodic polarization curves involve three anodic peaks correlated to the electroformation of Cu2O, CuO and Cu(OH)2 on the anode surface. The presence of these species in the passive layer has been confirmed by XPS examination. An addition of the halide anions enhances the peak currents of anodic peaks and tends to rupture the passive layer inducing the pitting corrosion. The critical pitting potentials decrease with rising halide concentration while the alkali concentration has an opposite effect. The accelerating effect of Cl- to pitting corrosion is greater than that of Br-. The pitting corrosion was explained by an instantaneous nucleation and growth of anion salt nuclei. Three cathodic peaks on cyclic voltammetric curve were assigned to the electroreduction of pitting corrosion products, Cu(II) and Cu(I) oxides, respectively.

Separation of sodium chromate from high alkaline media based on precipitation transformation using barium hydroxide

2020 ◽  
Vol 44 (28) ◽  
pp. 12048-12057
Author(s):  
Xiaoyu Tang ◽  
Haifeng Wu ◽  
Xuejun Quan ◽  
Chengfei Feng ◽  
Gang Li ◽  
...  
Keyword(s):  
Barium Hydroxide ◽  
Alkaline Media ◽  
Precipitation Process ◽  
Sodium Chromate ◽  
High Concentration ◽  
Naoh Solution

Separation and recovery of chromium from a high-concentration NaOH solution by a Ba(OH)2 precipitation process.

Inspection and mitigation for pitting corrosion on stainless steel process piping to prevent process safety event and loss production opportunity in Medco E&P

2021 ◽  
Author(s):  
I. Rosyadi
Keyword(s):  
Stainless Steel ◽  
Pitting Corrosion ◽  
Sun Exposure ◽  
Passive Layer ◽  
Process Safety ◽  
Pipe Surface ◽  
Corrosion Propagation ◽  
Process Piping ◽  
Safety Event ◽  
Steel Piping

Stainless steel piping has excellent corrosion resistant properties, both internal or external piping surface. In humid circumstances, sea vapor containing chlorine will be trapped on the pipe surface, especially pipes below deck with minimum sun exposure (more humid). Chlorine on the external pipe surface will damage the passive layer of stainless steel pipe. Damage speed is faster than recovery of passive layer stainless steel. This condition lead to a lot of localized pitting corrosion spread. The corrosion was detected visually and carried out with dye penetrant inspection to assure pitting condition. Actual dimension of pitting (depth, diameter) cannot be measured due to limitation of the NDE technique. This pitting corrosion can result hydrocarbon leakage as a process safety event that contributes loss of production opportunity. Without modification circumstances, this condition can be stopped immediately by application of a viscos elastic coating to prevent pitting corrosion propagation. Application of viscos elastic coating is simpler and faster when compared to conventional coating. Viscos elastic coating will protect stainless steel piping surface against oxygen and chloride in humid circumstances so that stainless steel can recover passive layer and stop pitting corrosion.

In situ Mössbauer Study of the Passive Layer Formed on the Iron Anode in Alkaline Electrolyte

1999 ◽  
Vol 64 (12) ◽  
pp. 2044-2060 ◽  
Author(s):  
Karel Bouzek ◽  
Martin Nejezchleba
Keyword(s):  
Mössbauer Spectra ◽  
Sodium Hydroxide Solution ◽  
Passive Layer ◽  
Iron Electrode ◽  
Ex Situ ◽  
Anode Surface ◽  
Alkaline Electrolyte ◽  
Mossbauer Spectra ◽  
Wide Range

In situ Mössbauer spectra of the iron electrode at anodic potential were measured in sodium hydroxide solution over a wide range of concentrations (0.1 - 14 mol l-1). It was found that the in situ Mössbauer spectra exhibit generally one sextet and one doublet corresponding to the oxide layer on the anode surface. Parameters of these spectra show only minor variations within the electrolyte concentration range of 0.1 - 7 M NaOH. A pronounced change in the spectra was observed in 14 M NaOH. The major processes taking place in the anode surface layer are based on the break-down of protective properties of the passive layer, incipient intense metal dissolution and subsequent oxidation. Important differences were also found between in situ and ex situ spectra measurements.

Pitting Corrosion of Zn Peculiarly Caused by Acetate Anions

2016 ◽  
Vol 230 (10) ◽  
Author(s):  
Hesham S. Abdel-Samad ◽  
Hamdy H. Hassan
Keyword(s):  
Passive Film ◽  
Pitting Corrosion ◽  
Potentiodynamic Polarization ◽  
Corrosion Behaviour ◽  
Passive Layer ◽  
Acetate Solution ◽  
Layer Formation ◽  
Potentiodynamic Polarization Curve ◽  
Pitting Potential ◽  
Formation Region

AbstractThe corrosion behaviour of zinc metal was studied in acetate solutions. The potentiodynamic polarization curve in 0.1 M acetate solution displays an anodic peak (A1) owing to the anodic dissolution of zinc followed by a passive layer formation region. Breakdown of the passive film and the initiation of pitting corrosion were observed beyond the pitting potential (

scholarly journals The Confocal Scanning Laser Microscopic Study of the Pitting Corrosion on Sputter-Deposited W-Ti Alloys in 1 M NaOH Solution

1970 ◽  
Vol 26 (1) ◽  
pp. 17-26
Author(s):  
Jagadeesh Bhattarai
Keyword(s):  
Passive Film ◽  
Pitting Corrosion ◽  
Corrosion Potential ◽  
Open Circuit ◽  
Scanning Laser ◽  
Ti Alloys ◽  
Naoh Solution ◽  
Confocal Scanning ◽  
Confocal Scanning Laser ◽  
Sputter Deposited

The pitting corrosion of the passive films formed on the surface of sputter-deposited W-30Ti and W-53Ti alloys after immersion for 24 hours in alkaline 1 M NaOH soution at 25°C was studied by using the surface sensitive technique of the confocal scanning laser microscopic (CSLM) technique including corrosion tests and electrochemical measurements. The higher corrosion rate of the W-30Ti alloy (i.e., about 3x 10-2 mm/y) than those of the W-53Ti and W-90Ti alloys (i.e., about 4-5 x 10-3 mm/y) was mostly due to the deep type of pitting corrosion observed on the surface of the passive film formed on the W-30Ti alloy in 1 M NaOH solution. The shallow type of pits was developed on the surface of the passive film formed on the W-53Ti alloy, whereas no pitting corrosion on the titanium-rich W-90Ti alloy.Keywords: Pitting corrosion; Open circuit corrosion potential; Corrosion test; CSLM studyTribhuvan University Journal Vol. XXVI, No. 1, 2009 Page: 17-26

scholarly journals Anodic behaviour of Zn0.5Al doped with molybdenum in acidic, neutral and alkaline media

2021 ◽  
Vol 11 (2) ◽  
pp. 187-194
Author(s):  
Z. R. Obidov ◽  
P. R. Ibrohimov ◽  
F. A. Rahimov ◽  
I. N. Ganiev
Keyword(s):  
Sweep Rate ◽  
Potential Sweep Rate ◽  
Alkaline Media ◽  
Favourable Effect ◽  
Neutral Medium ◽  
Potential Sweep ◽  
Stationary Potential ◽  
Zinc Alloys ◽  
Anodic Behaviour ◽  
Acidic And Alkaline Media

The paper presents the results of a potentiodynamic study of the anodic behaviour of Zn0.5Al doped with molybdenum in the acidic (0.1 M, pH = 1; 0.01 M, pH = 2; 0.001 M, pH = 3), neutral (0.03, 0.3, 3%, pH = 7) and alkaline (0.001 M, pH = 10; 0.01 M, pH = 11; 0.1 M, pH = 12) media of HCl, NaCl and NaOH electrolytes. In the potentiodynamic mode with an electrode potential sweep rate of 2 mV/s, all Zn0.5Al-Mo samples containing from 0.01 to 1.0 wt% of molybdenum demonstrated a shift in the potentials of corrosion, pitting formation and repassivation. These potentials shift towards negative values in acidic and alkaline media, while shifting to positive values in a neutral medium. It was established that an increase in the concentration of electrolytes led to a shift of all the considered potentials towards negative values in all media - acidic, neutral and alkaline. This dependence is associated with the specific features of the process of anodic dissolution of alloys during the formation of an oxide film on their surface. The significance of the dependence of the stationary potential of free corrosion of alloys on time for establishing the passivity of surfaces in acidic, neutral and alkaline media was shown. It was determined that zinc alloys doped with molybdenum are resistant to pitting corrosion in all the investigated media. This resistivity is particularly high in acidic (0.001 M), neutral (0.03%) and alkaline (0.001 M) media of HCl, NaCl and NaOH electrolytes. The favourable effect of molybdenum on both the anodic behaviour of Zn0.5Al and the overall increase in the corrosion resistance of alloys was demonstrated. In comparison with undoped Zn0.5Al alloys, the corrosion rate of alloys doped with molybdenum (0.01-1.0 wt%) is 2-2.5 times lower. The proposed compositions of Zn0.5Al-Mo alloys can be used as noncorrosive coatings for steel products.

scholarly journals Effect of NaOH concentration and curing regime on geopolymer

2017 ◽  
Vol 10 (6) ◽  
pp. 1174-1181 ◽  
Author(s):  
C. N. LIVI ◽  
W. L. REPETTE
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Curing Temperature ◽  
Lower Amount ◽  
Alkali Concentration ◽  
X Ray Diffraction ◽  
Highest Weight ◽  
Thermogravimetric Data ◽  
Naoh Solution ◽  
Curing Regime

Abstract The effect of alkali concentration and curing temperature regime on fly ash-based geopolymer pastes was investigated in this study by using NaOH solutions. Prismatic specimens were molded, cured at 65 °C and 85 °C and submitted to flexural and compressive strength tests. Unreacted fly ash and geopolymers were characterized by X-ray diffraction and thermogravimetric analysis. In general, the mechanical strength was enhanced by increasing the molar concentration and the curing temperature. This trend was confirmed by thermogravimetric data. However, for a lower amount of NaOH there were no significant differences between the strength results. The mixture with the highest strength was obtained with the 16 M NaOH solution and curing temperature of 85 °C, which resulted in flexural strength of 4.20 MPa, compressive strength of 21.35 MPa and also the highest weight loss of 9.89%.

Improved permeability of autohydrolyzed poplar sapwood against sodium hydroxide for CMP production

Holzforschung ◽  
2018 ◽  
Vol 72 (5) ◽  
pp. 347-355 ◽  
Author(s):  
Xiaoya Jiang ◽  
Qingxi Hou ◽  
Wei Liu ◽  
Honglei Zhang ◽  
Yudi Cui ◽  
...  
Keyword(s):  
Sodium Hydroxide ◽  
Cell Walls ◽  
Radial Direction ◽  
Sodium Hydroxide Solution ◽  
Axial Direction ◽  
Positive Influence ◽  
Skeletal Structure ◽  
Alkali Concentration ◽  
Mechanical Pulp ◽  
Naoh Solution

AbstractPoplar sapwood chips were autohydrolyzed at three severity levels and subsequently treated with alkali for the production of chemi-mechanical pulp (CMP). The aim was to study the variation of the principal pathways for sodium hydroxide solution and the alkali concentration and distribution inside the autohydrolyzed chips as a function of autohydrolysis (AH) severity. The tyloses in the vessels and some pit membranes were partly dissolved after AH, while the skeletal structure of the fiber and vessel cell walls remained intact. AH had a positive influence on the diffusion and the uniform distribution of NaOH solution both in the axial and radial direction of the chips, but the axial direction was more favored than the radial one.

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