Zinc dissolution in Leclanche electrolyte

1974 ◽  
Vol 27 (11) ◽  
pp. 2467 ◽  
Author(s):  
DB Matthews ◽  
PG Capps
Keyword(s):  
Corrosion Rate ◽  
Metallic Impurity ◽  
Cathodic Reaction ◽  
Electrolyte Layer ◽  
Zinc Surface ◽  
Diffusion Controlled ◽  
Layer 2 ◽  
Order Of Magnitude ◽  
Zinc Dissolution

The rate and morphology of zinc dissolution were studied in a Leclanche electrolyte of composition 0.5 mol dm-3 ZnCl2 and 5 mol dm-3 NH4Cl. A gelled electrolyte layer 2 x 10-3 m thick on the zinc surface was found to reduce the corrosion rate by an order of magnitude and to promote even dissolution. The corrosion results are interpreted in terms of a diffusion-controlled cathodic reaction involving O2 dissolution and metallic impurity deposition.

Discussion of Oxygen Threshold Level for Corrosion Management in Seawater Injection Systems

2021 ◽  
Author(s):  
Jean Vicente Ferrari
Keyword(s):  
Corrosion Rate ◽  
Oxygen Reduction ◽  
Water Injection ◽  
Steel Corrosion ◽  
Threshold Level ◽  
International Standards ◽  
Limiting Current ◽  
Order Of Magnitude ◽  
The Impact ◽  
Oxygen Concentrations

Abstract Generally, in water injection systems, oxygen levels starting from around eight ppm are deoxygenated to below 50 ppm, following international standards' guidelines. This work aims to discuss the impact of such a magnitude value of oxygen contamination on steel corrosion in seawater injection systems by analysing theoretical polarisation curves and results from published works with different approaches. Corrosion models consider mass-transfer controlled diffusion of oxygen to predict the maximum steel corrosion rate, which depends on the oxygen limiting current, which in turn is strongly influenced by flow velocity. The effect of free chlorine on corrosion in seawater injection systems has also been considered and included in an oxygen equivalent parameter. In such systems, where oxygen reduction is the key cathodic reaction, the corrosion process may be under cathodic activation control, independent of flow at higher velocities or when erosion-corrosion begins. In this work, theoretical polarisation curves were constructed by using published oxygen and chlorine cathodic limiting currents (iLc) on carbon steel and a noble metal electrode, respectively. Aerated (200 ppb and 9000 ppb of oxygen) and deaerated conditions (50 ppb of oxygen) and the presence of 300 ppb of chlorine were applied to the assumed exchange current densities (io). Neutral (pH 7) and acid (pH 4) conditions (considering the presence of CO2) were also assumed to be at room temperature and pressure. Since the corrosion rate in lower oxygen concentrations (ppb order of magnitude) may result in corrosion rates of the same order of magnitude than in higher oxygen concentrations (ppm order of magnitude) when comparing and analysing results from experimental, semi-empirical or mechanistic approaches, it is necessary to weigh up the effects of both steel surface (bare or scaled/corrosion products) and flow. At oxygen concentrations below 200 ppb and under acid conditions, the contribution of H+ reduction on corrosion rate starts to be higher than oxygen reduction, mainly in the absence of chlorine.

scholarly journals Effects of tungsten, chromium and zirconium on the corrosion behavior of ternary amorphous W–Cr–Zr alloys in 1 M NaOh solution

1970 ◽  
Vol 9 (9) ◽  
pp. 39-43
Author(s):  
Basu Ram Aryal ◽  
Jagadeesh Bhattarai
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Corrosion Rates ◽  
Corrosion Resistance Property ◽  
Naoh Solution ◽  
Order Of Magnitude ◽  
Sputter Deposited ◽  
Zr Alloys

Simultaneous additions of tungsten, chromium and zirconium in the chromium- and zirconium-enriched sputter-deposited binary W-xCr and W-yZr are effective to improve the corrosion resistance property of the ternary amorphous W- xCr-yZr alloys after immersion for 240 h in 1 M NaOH solution open to air at 25°C. The corrosion rates of all the examined sputter-deposited (10-57)W-(18-42)Cr-(25-73)Zr alloys is higher than those of alloy-constituting elements (that is, tungsten, chromium and zirconium) in aggressive 1 M NaOH solution open to air at 25°C. The corrosion rates of all the examined sputter−deposited W–xCr–yZr alloys containing 10-57 at% tungsten, 18-42 at% chromium and 25-73 at% zirconium were in the range of 1.5-2.5 × 10−3 mm/y or lower which are more than two orders of magnitude lower than that of sputter-deposited tungsten and even about one order of magnitude lower than those of the sputter-deposited zirconium in 1 M NaOH solution. Keywords: Ternary W–Cr–Zr alloys; Amorphous; Corrosion rate; Open circuit potential; 1 M NaOH. DOI: http://dx.doi.org/10.3126/sw.v9i9.5516 SW 2011; 9(9): 39-43

scholarly journals The Corrosion Behavior of Sputter-Deposited Nanocrystalline W-Cr Alloys in Nacl and NaohaSolutions

1970 ◽  
Vol 25 ◽  
pp. 53-61
Author(s):  
Minu Basnet ◽  
Jagadeesh Bhattarai
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Rate ◽  
Corrosion Behavior ◽  
Chromium Content ◽  
Open Circuit ◽  
Nacl Solution ◽  
Corrosion Rates ◽  
Naoh Solution ◽  
Order Of Magnitude ◽  
Sputter Deposited

The corrosion behavior of the sputter-deposited nanocrystalline W-Cr alloys wasstudied in 0.5 M NaCl and alkaline 1 M NaOH solutions at 25°C, open to air usingimmersion tests and electrochemical measurements. Chromium metal acts synergisticallywith tungsten in enhancing the corrosion resistance of the sputter-deposited W-Cr alloys soas to show higher corrosion resistance than those of alloy-constituting elements in both 0.5M NaCl and 1 M NaOH solutions. In particular, the nanocrystalline W-Cr alloys containing25-91 at% chromium showed about one order of magnitude lower corrosion rates (that is,about 1-2 × 10-3 mm.y-1) than those of tungsten and chromium metals even for prolongedimmersion in 0.5 M NaCl solution at 25°C. On the other hand, the corrosion rate of thesputter-deposited W-Cr alloys containing 25-75 at % chromium was decreased significantlywith increasing chromium content and showed lowest corrosion rates (that is, 1.5-2.0 × 10-3 mm.y-1) after immersed for prolonged immersion in 1 M NaOH solution. The corrosion ratesof these nanocrystalline W-(25-75)Cr alloys are nearly two orders of magnitude lower thanthat of tungsten and more than one order of magnitude lower corrosion rate than that ofsputter-deposited chromium metal in 1 M NaOH solution. The corrosion-resistant of all theexamined sputter-deposited W-Cr alloys in 0.5 M NaCl solution is higher than in alkaline 1M NaOH solution at 25°C. Open circuit potentials of all the examined W-Cr alloys areshifted to more noble direction with increasing the chromium content in the alloys afterimmersion for 72 h in both 0.5 M NaCl and 1 M NaOH solutions at 25°C, open to air.Keywords: Sputter deposition, nanocrystalline W-Cr alloys, corrosion test, electrochemicalmeasurement, NaCl and NaOH solutions.DOI:  10.3126/jncs.v25i0.3300Journal of Nepal Chemical Society Volume 25, 2010 pp 53-61

The Reaction of Organophosphorus Radicals With Vinyl Acetate and Acrylonitrile in the Presence of an Aminoxyl Radical Scavenger

1995 ◽  
Vol 48 (3) ◽  
pp. 625 ◽  
Author(s):  
WK Busfield ◽  
ID Grice ◽  
ID Jenkins
Keyword(s):  
Vinyl Acetate ◽  
Hydrogen Abstraction ◽  
Phosphate Esters ◽  
Radical Scavenger ◽  
Diphenylphosphine Oxide ◽  
Dimethyl Phosphite ◽  
Radical Trapping ◽  
Diffusion Controlled ◽  
Order Of Magnitude

The radical-trapping technique employing 1,1,3,3-tetramethyl-1,3-dihydro-2H-isoindol-2-yloxyl (1) as a radical scavenger has been used to study the reaction of diphenylphosphinoyl (2) and dimethoxyphosphinoyl (3) radicals with vinyl acetate and acrylonitrile. The phosphorus- centred radicals were generated by hydrogen abstraction from diphenylphosphine oxide and dimethyl phosphite respectively. Diphenylphosphine oxide was approximately three times as reactive as dimethyl phosphite towards hydrogen abstraction by t- butoxyl radicals and four times as reactive as tetrahydrofuran (towards abstraction of an α-hydrogen). Diphenylphosphinoyl radicals were found to be relatively nucleophilic and, in competition experiments, reacted about an order of magnitude faster with acrylonitrile than with vinyl acetate. Dimethoxyphosphinoyl radicals were rather less nucleophilic and reacted only twice as fast with acrylonitrile as they did with vinyl acetate. In the presence of excess aminoxyl (1), both diphenylphosphinoyl and dimethoxyphosphinoyl radicals were efficiently scavenged to produce stable phosphinic and phosphate esters respectively. The rate of scavenging was close to diffusion-controlled (c. 1.8×109 1. mol-1 s-1).

scholarly journals Inhibition of Brass Corrosion in Acid Medium Using Thiazoles

2013 ◽  
Vol 14 ◽  
pp. 87-102
Author(s):  
K.K. Taha ◽  
Musa E. Mohamed ◽  
S.A. Khalil ◽  
S.A. Talab
Keyword(s):  
Weight Loss ◽  
Thermal Properties ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Corrosion Rate ◽  
Heat Exchangers ◽  
Corrosion Inhibitors ◽  
Inhibition Efficiency ◽  
Electrochemical Impedance ◽  
Zinc Dissolution

Brass as an alloy composed mainly of copper is great industrial uses such as heat exchangers and similar other facility due to its good thermal properties. Due to the presence of the considerable ratio of zinc the alloy suffers from zinc dissolution or dezincification. Dezincification rate increases with the increase in the ratio of zinc in the alloy. In this study benzothiazole (BTH) and its substituent’s 2-methylbenzothiazole (MeBTH), 2-aminobenzothiazole (ABTH), 2-mercaptobenzothiazole (MBTH) and 2-phenylbenzothiazole (PhBTH) have been used as corrosion inhibitors for α-brass in stirred 0.1 M HClO4. The methods of investigation include weight loss, Tafel and linear polarizations and electrochemical impedance spectroscopy. The order of inhibition efficiency (%E) was calculated and the values obtained has indicated the sequence of inhibition efficiency was found to be BTH < MeBTH < ABTH < PhBTH < MBTH. The calculated values of thermodynamic parameters support this order. The inhibitors were found to suppress the corrosion rate by the formation of films which were identified by IR, SEM and EDAX techniques.

The Effect of Trivalent Chromium Process on Al-Zn-In Pigments in Epoxy Primer on the Corrosion Protection of AA2024-T3

CORROSION ◽  
10.5006/3393 ◽  
2020 ◽  
Vol 76 (1) ◽  
pp. 103-113 ◽  
Author(s):  
Xi Wang ◽  
G.S. Frankel
Keyword(s):  
Aluminum Alloy ◽  
Corrosion Rate ◽  
Potentiodynamic Polarization ◽  
Treatment Time ◽  
Trivalent Chromium ◽  
Accelerated Corrosion ◽  
Epoxy Primer ◽  
Active Aluminum ◽  
Order Of Magnitude ◽  
The One

Active metal pigments in metal-rich coatings are oxidized preferentially and provide sacrificial protection to more-noble metallic substrates. Al-rich primer (AlRP), which contains pigment particles made from an active aluminum alloy (Al-5Zn-0.02In), uses this mechanism to provide a chromate-free epoxy primer system. To address the high self-corrosion rate of active aluminum pigments, the active aluminum pigment particles are pretreated using trivalent chromium process (TCP). In this study, the effects of different TCP treatment times were evaluated, and coating protection properties were studied. Potentiodynamic polarization tests were performed in aerated 0.1 M NaCl solution for a TCP-treated bulk active aluminum alloy and for AA2024-T3. The potentiodynamic polarization curves show that the corrosion potential of the bulk active aluminum alloy is about 500 mV lower than that of AA2024-T3. Therefore, bulk active aluminum alloy is a candidate alloy for cathodic protection of AA2024-T3. In addition, the TCP treatment reduces the corrosion rate of the bulk active aluminum alloy by one order of magnitude. AlRP-coated AA2024-T3 panel samples were scribed and exposed in corrosion chambers, and the cross section of each coating was evaluated by scanning electron microscopy and energy dispersive x-ray spectroscopy mapping. The accelerated corrosion exposure results show that AlRP coatings containing TCP-treated particles provided better protection to the scribe than the one with bare pigment particles. The adhesion of the AlRPs based on pull-off adhesion tests was similar regardless of the TCP treatment time of the pigments, but the adhesion of AlRP was reduced in comparison to a neat epoxy coating.

Examination of the Zinc Cementation of Cadmium in Aqueous Solutions

1987 ◽  
Vol 19 (3-4) ◽  
pp. 333-344 ◽  
Author(s):  
J. P. Gould ◽  
I. B. Escovar ◽  
B. M. Khudenko
Keyword(s):  
Hydrogen Ions ◽  
Electrochemical System ◽  
Solution Ph ◽  
Hydride Ion ◽  
System A ◽  
First Order Kinetics ◽  
Diffusion Controlled ◽  
Reaction Stoichiometry ◽  
Kinetics Of ◽  
Zinc Dissolution

The kinetics of the cementation of cadmium by zinc have been studied over a range of solution pH values and initial cadmium concentrations. The kinetics were interpreted in terms of a model postulating a transition from a migration controlled mechanism with consequent half order kinetics to a diffusion controlled regime following first order kinetics. The conditions under which each mechanism was found to apply were consistent with the model in which the immediate reductant was hydride ion generated by the interaction of hydrogen ions with the zinc. The reaction stoichiometry was remarkable in that conditions were observed under which more than the theoretical one mole of cadmium per mole of zinc could be reduced. This was ascribed to the electrolysis of water by the induced electrochemical system. A lag in both cadmium cementation and zinc dissolution was observed in many runs. The zinc dissolution was found to commence about 25% sooner than cadmium cementation, a fact ascribed to the establishment of the reducing electrochemical system.

Monitoring X65 Steel Internal Corrosion in Humidified N2 containing H2S using Membrane-based Electrochemical Sensors

CORROSION ◽  
10.5006/3454 ◽  
2021 ◽  
Author(s):  
Timothy Duffy ◽  
Derek Hall ◽  
Margaret Ziomek-Moroz ◽  
Serguei Lvov
Keyword(s):  
Relative Humidity ◽  
Natural Gas ◽  
Corrosion Rate ◽  
Electrochemical Sensors ◽  
Element Analysis ◽  
Internal Corrosion ◽  
Natural Gas Pipelines ◽  
Corrosion Rates ◽  
Order Of Magnitude ◽  
X65 Steel

We report here on a new membrane-based electrochemical sensor (MBES) that may provide an important utility in monitoring and characterizing internal corrosion of natural gas pipelines. Using this sensor, we have measured the corrosion rate of X65 steel exposed to H2S in humidified environments up to 60 °C. Consistent with our earlier CO2 study, the membrane’s conductivity did not change when exposed to H2S-contaning acidic gas. Introducing H2S consistently increased the measured corrosion rate between testing conditions, though corrosion rates were typically less than 2 μm y-1. At 30 °C, the corrosion rate doubled from 7.3 to 14 nm y-1 below a relative humidity of 30 %, and increased by an order of magnitude (0.19 μm y-1 to 1.9 μm y-1) at 55 % relative humidity, showing that the influence of H2S on corrosion increases dramatically with larger humidity. Trends with relative humidity match industry expectations: corrosion rate is low (&lt;0.25 μm y-1) without the presence of a condensed aqueous phase, but increases as the water content of the system increases. The MBES was therefore able to captures relevant corrosion trends, even while the corrosion rates would not have presented a serious threat to any natural gas pipeline. As such, the MBES can be used to detect the onset of emerging corrosion threats before they occur. Field emission scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed that H2S reacted with the metal covered by the membrane phase, showing evidence of sulfur-rich sites on the X65 surface. In addition, finite element analysis confirmed that electrochemical measurements and data analysis techniques could be successfully used for this membrane-based sensor, despite its unconventional cell geometry.

Effect of Oxygen Transport and Resistivity of the Environment on the Corrosion of Steel

1990 ◽  
Vol 212 ◽  
Author(s):  
E. Escalante ◽  
T. Oka ◽  
U. Bertocci
Keyword(s):  
Spatial Distribution ◽  
Corrosion Rate ◽  
Oxygen Transport ◽  
Yucca Mountain ◽  
Wide Range ◽  
Order Of Magnitude ◽  
Mountain Environment ◽  
Effect Of Oxygen ◽  
Corrosion Of Steel

ABSTRACTThis study is directed at investigating the rate of corrosion and its spatial distribution that develop under conditions where transport of oxygen and conductivity of the environment are controlled over a wide range, including low conductivity as expected in the Yucca Mountain environment. The results indicate that the corrosion rate of steel is directly related to the rate of oxygen transport over several orders of magnitude, and increasing conductivity by one order of magnitude increases corrosion rate by a factor of two or three. Of greater significance is the result that indicates that as conductivity of the environment decreases, and corrosion rate decreases, the degree of localized attack increases.

Effect of flow rate on the corrosion behaviour of API 5L X80 steel in water-saturated supercritical CO2 environments

CORROSION ◽  
10.5006/3939 ◽  
2021 ◽  
Author(s):  
Jonas da Silva de Sa ◽  
Wenlong Ma ◽  
Joshua Owen ◽  
Yong Hua ◽  
Anne Neville ◽  
...  
Keyword(s):  
Corrosion Rate ◽  
Flow Rate ◽  
Corrosion Behaviour ◽  
Localized Corrosion ◽  
General Corrosion ◽  
Rotating Shaft ◽  
Order Of Magnitude ◽  
X80 Steel ◽  
Condensed Water ◽  
Water Saturated

The effect of the water-saturated supercritical carbon dioxide flow rate on the corrosion behaviour of API 5L X80 steel at a temperature of 35 oC and pressure of 80 bar was investigated. Tests were carried out with the samples attached to a rotating shaft inside an autoclave. Results indicate that increasing the scCO2 flow rate had no significant influence on the general/localized corrosion rate under the various dynamic conditions considered. The average general corrosion rate was 0.064 mm/year, while the average measured pitting penetration rates were one order of magnitude higher. The size of the corrosion features on the surface of the samples, which were believed to provide an indication as to the size of the condensed water droplets, were much smaller than the calculated critical droplet size needed to be displaced by the flow, supporting the theory as to why flow rate had little effect on the corrosion response.

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