Effect of primary product stability on the anodic dissolution rate of metals

2012 ◽  
Vol 48 (3) ◽  
pp. 297-303
Author(s):  
A. V. Noskov
Author(s):  
Frank Y. Cheng

A thermodynamic model was developed to determine the interactions of hydrogen, stress and anodic dissolution at the crack-tip during near-neutral pH stress corrosion cracking in pipelines. By analyzing the free-energy of the steel in the presence and absence of hydrogen and stress, it is demonstrated that a synergism of hydrogen and stress promotes the cracking of the steel. The enhanced hydrogen concentration in the stressed steel significantly accelerates the crack growth. The quantitative prediction of the crack growth rate in near-neutral pH environment is based on the determination of the effect of hydrogen on the anodic dissolution rate in the absence of stress, the effect of stress on the anodic dissolution rate in the absence of hydrogen, the synergistic effect of hydrogen and stress on the anodic dissolution rate at the crack-tip and the effect of the variation of hydrogen concentration on the anodic dissolution rate.


2020 ◽  
Vol 25 (3) ◽  

It is known that the disadvantages of ferrosilide earthing devices are their fragility, which leads to their frequent mechanical damage. Their fragility is increased with increasing silicon content. The solution to this problem is to reduce the content of silicon in the alloy, but this greatly increases the rate of dissolution of the resulting alloy. As a result, the possibility of reducing the dissolution rate of ferrosilides with a silicon content of 9…12% due to thermal oxidation and treatment in a phosphoric acid medium was studied. The most promising method for anode grounding conductors is the method of processing materials in orthophosphoric and metaphosphoric acids with the formation on the surface of a phase of iron silicide highly resistant to anodic dissolution due to selective etching of the alloy. The relationship between the phase composition of the films showed that mainly phases of silicon oxide (SiO2) and magnetite (Fe3O4) predominate in the alloys, as a result of which the dissolution rate is significantly reduced. As a result of heat treatment of ferrosilide alloys with a silicon content of less than 14%, a decrease in the dissolution rate does not occur due to the high porosity of the formed films and the presence of phases that do not have protective properties. The anodic dissolution rate is the lower, when the grain size of the alloy used is the larger.


Metals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 487
Author(s):  
Changqi Yan ◽  
Boyu Yuan ◽  
Zhenhui Li ◽  
Liang Li ◽  
Chao Wang

The anodic dissolution of copper in chloride electrolytes with different pH has been investigated by using polarization measurements and digital holography. In acidic and neutral NaCl solutions, the oxidation processes of copper are almost the same: copper firstly dissolves as cuprous ions, which then produces the CuCl salt layer. The dissolution rate in the acidic solution is a little higher than that in the neutral. However, the mechanism is quite different in the alkaline NaCl solution: copper turns passive easily due to the formation of a relatively stable Cu2O film which results in pitting, and the dissolution rate of copper decreases before pit initiation.


2016 ◽  
Vol 2 (2) ◽  
pp. 91-95
Author(s):  
Neelima Rani T ◽  
Pavani A ◽  
Sobhita Rani P ◽  
Srilakshmi N

This study aims to formulate solid dispersions (SDs) of Simvastatin (SIM) to improve the aqueous solubility, dissolution rate and to facilitate faster onset of action. Simvastatin is a BCS class II drug having low solubility & therefore low oral bioavailability. In the present study, SDs of simvastatin different drug-carrier ratios were prepared by kneading method. The results showed that simvastatin solubility & dissolution rate enhanced with polymer SSG in the ratio 1:7 due to increase in wetting property or possibly may be due to change in crystallinity of the drug.


1994 ◽  
Vol 80 (4) ◽  
pp. 294-299
Author(s):  
Katsumi MORI ◽  
Toshiro KITAHARA ◽  
Kunihiko NAKASHIMA
Keyword(s):  

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