Anodic polarization of tungsten in neutral and alkaline solutions under conditions of anode film growth

1972 ◽  
Vol 23 (3) ◽  
pp. 161-167 ◽  
Author(s):  
I. A. Ammar ◽  
R. Salim
Keyword(s):  
Anodic Polarization ◽  
Film Growth ◽  
Alkaline Solutions ◽  
Anode Film

Plasma Electrolytic Oxidation (PEO) Coatings on Aluminum Alloys: Kinetics and Formation Mechanism

2019 ◽  
Author(s):  
Alex Lugovskoy ◽  
Lyubov Snizhko
Keyword(s):  
Aluminum Alloys ◽  
Plasma Electrolytic Oxidation ◽  
Anodic Polarization ◽  
Point Of View ◽  
Alkaline Solutions ◽  
Inorganic Polymers ◽  
Electrolytic Oxidation ◽  
Plasma Electrolytic ◽  
Peo Coatings ◽  
First Time

In this review, the main kinetics and mechanism regularities of plasma electrolytic oxidation (PEO) of aluminum alloys are discussed. The material and heat balances of the PEO process, including anomalous gas evolution and possible thermochemical reactions are presented for the first time. Side effects accompanying spark discharges from both the surface and the electrolyte sides are analyzed. The influences of electrical regime (direct, alternative, and pulse current) on the rate of coatings growth are summarized from the electrochemical point of view. Different modes of anodic polarization and electrolyte composition (alkaline solutions with inorganic polymers and dispersed constituents) are discussed in the applicative aspect.

Inhibition of Corrosion of Commercial Aluminum In Alkaline Solutions

CORROSION ◽  
1961 ◽  
Vol 17 (1) ◽  
pp. 39t-44t ◽  
Author(s):  
J. SUNDARARAJAN ◽  
T. L. RAMA CHAR
Keyword(s):  
Sodium Hydroxide ◽  
Metal Surface ◽  
Anodic Polarization ◽  
Corrosion Process ◽  
Alkaline Solutions ◽  
Corrosion Rates ◽  
Mixed Control ◽  
Polarization Studies ◽  
Percent Manganese

Abstract The corrosion rates for commercial aluminum, containing 4 percent manganese and 3 percent iron, have been determined in sodium hydroxide solutions under different conditions. The inhibitor efficiencies have been calculated for the following substances, the efficiency decreasing from 90 to 60 percent in the order: agar-agar, gum-acaciae, dextrin, gelatin, glue. Corrosion potentials have been measured with and without dextrin inhibitor, and cathodic and anodic polarization studies made. The results show that the dissolution of the metal is electrochemical in character. The corrosion process appears to be under mixed control with predominance of action of dextrin inhibitor on the anodic areas of the metal surface. 6.4.2, 4.3.3, 5.8.2

NEW APPROACHES TO THE STUDY OF ELECTROCHEMICAL DECARBOXYLATION AND THE KOLBE REACTION: PART III. QUANTITATIVE ANALYSIS OF DECAY AND DISCHARGE TRANSIENTS AND THE ROLE OF ADSORBED INTERMEDIATES

1963 ◽  
Vol 41 (1) ◽  
pp. 55-67 ◽  
Author(s):  
B. E. Conway ◽  
M. Dzieciuch
Keyword(s):  
Reaction Mechanism ◽  
Anodic Polarization ◽  
Film Growth ◽  
Open Circuit ◽  
Gas Evolution ◽  
Autocatalytic Decomposition ◽  
Kolbe Reaction ◽  
Current Potential ◽  
Potential Curves

Galvanostatic cathodic discharge and open-circuit decay transients have been obtained for the decarboxylation of formate in formic acid and interpreted quantitatively in terms of the adsorption of intermediates in the reaction. These intermediates are identified with HCOO• radicals. Extended anodic polarization at platinum and particularly at palladium leads to the formation of films of an anodic product which are considerably thicker than a monolayer. After relatively long times (> 100 seconds) of anodic polarization, the film growth obeys the inverse logarithmic rate law deduced by Mott and Cabrera. The thick films which are formed at palladium are believed to be responsible, upon autocatalytic decomposition, for the delayed gas evolution phenomenon observed at this metal.A new method for deduction of adsorption pseudocapacitance and charge associated with the ad-layer from open-circuit decay curves and Tafel parameters is used to obtain the pseudo-capacitance and charge associated with the transition region in the current–potential curves for the formate decarboxylation. It is shown that this region corresponds to filling of the surface with adsorbed intermediates formed in the reaction. These observations are shown to support the reaction mechanism proposed in Part I.

Effect of Phosphorus on the Corrosion Resistance of Nickel Electrocoatings

2015 ◽  
Vol 228 ◽  
pp. 310-316
Author(s):  
B. Łosiewicz ◽  
Magdalena Popczyk ◽  
Magdalena Szklarska ◽  
Patrycja Osak
Keyword(s):  
Corrosion Resistance ◽  
Anodic Polarization ◽  
Open Circuit Potential ◽  
Electrochemical Corrosion ◽  
Amorphous Structure ◽  
Open Circuit ◽  
Alkaline Solutions ◽  
Nickel Coatings ◽  
Effective Manner ◽  
Passivation Potential

The electrodeposited Ni-P coatings are commonly used for their electrocatalytic properties towards hydrogen evolution reaction. However, their corrosion resistance in concentrated alkaline solutions is still less known. In this work, the effect of phosphorus on the resistance of nickel electrodeposits to electrochemical corrosion in 5 M KOH solution, was studied. Open circuit potential and anodic polarization measurements were performed to determine parameters of the corrosion resistance of the crystalline Ni deposit and amorphous Ni-P electrocoating. It was found that alloying of nickel with phosphorus is the effective manner of the improvement of the corrosion resistance of the nickel coatings. The obtained Ni-P electrode material contained 10 wt.% of P and revealed amorphous structure. The increase in the corrosion resistance of the Ni90P10system as compared to that determined for comparable Ni polycrystalline electrode was due to phosphate formation responsible for broad passivation potential in alkaline medium and amorphous structure.

Sign in / Sign up

Export Citation Format

Share Document