scholarly journals Diffusivity of Point Defects in the Passive Film on Stainless Steel

2011 ◽  
Vol 2011 ◽  
pp. 1-6 ◽  
Author(s):  
A. Fattah-alhosseini ◽  
M. H. Alemi ◽  
S. Banaei
Keyword(s):  
Stainless Steel ◽  
Film Formation ◽  
Passive Films ◽  
Defect Model ◽  
Exponential Relationship ◽  
Donor Density ◽  
Oxygen Ion ◽  
Aisi 316 Stainless Steel ◽  
Aisi 316 ◽  
Semiconductor Properties

The semiconductor properties of passive films formed on AISI 316 stainless steel in sulfuric acid solution were studied by employing Mott-Schottky analysis in conjunction with the point defect model. The donor density of the passive films, which can be estimated by the Mott-Schottky plots, changes depending on the film formation potentials. Based on the Mott-Schottky analysis, an exponential relationship between donor density and the film formation potentials of the passive films was developed. The results showed that the donor densities evaluated from Mott-Schottky plots are in the range 2-3 × 1021 cm−3and decreased with the film formation potential. By assuming that the donors are oxygen ion vacancies and/or cation interstitials, the diffusion coefficient of the donors, (), is calculated to be approximately 3.12 × 10−16 cm2/s.

The Mechanism of Oxide Film Formation on AISI 316 Stainless Steel in Sulphate Solutions

2019 ◽  
Vol 16 (48) ◽  
pp. 67-77
Author(s):  
Cesar A. Sequeira ◽  
Diogo M. Santos ◽  
Jose Rodrigues Sousa ◽  
Paulo Brito
Keyword(s):  
Stainless Steel ◽  
Oxide Film ◽  
Film Formation ◽  
316 Stainless Steel ◽  
Aisi 316 Stainless Steel ◽  
Aisi 316

The Effect of Chloride Ions on the Passive Films of Titanium in Sulfuric Acids

2015 ◽  
Vol 227 ◽  
pp. 67-70 ◽  
Author(s):  
Jing Liu ◽  
Akram Alfantazi ◽  
Edouard Asselin
Keyword(s):  
Point Defect ◽  
Film Formation ◽  
Chloride Ions ◽  
Passive Films ◽  
Defect Model ◽  
Point Defect Model ◽  
Formation Potential ◽  
Donor Density

The effect of chloride ions on the passivity of titanium in sulfuric acids was investigated by potentiodynamic and potentiostatic anodizing, Mott-Schottky analysis and the point defect model (PDM). The anodizing results indicated that chloride ions facilitate the anodic passivity of titanium in sulfuric acids. Based on the Mott-Schottky analysis in conjunction with the PDM, it was shown that the donor density decreases exponentially with increasing film formation potential. Also, the results indicated that with the increasing concentration of chloride ions, the donor density decreases, while the diffusivity of the donors increases at the same film formation potential.

scholarly journals Breakdown and Evolution of the Protective Oxide Scales of AISI 304 and AISI 316 Stainless Steels under High-Temperature Oxidation

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
K. A. Habib ◽  
M. S. Damra ◽  
J. J. Saura ◽  
I. Cervera ◽  
J. Bellés
Keyword(s):  
Stainless Steel ◽  
Stainless Steels ◽  
Breakdown Point ◽  
304 Stainless Steel ◽  
Aisi 304 Stainless Steel ◽  
Protective Oxide ◽  
Aisi 304 ◽  
316 Stainless Steel ◽  
Aisi 316 Stainless Steel ◽  
Aisi 316

The failure of the protective oxide scales of AISI 304 and AISI 316 stainless steels has been studied and compared at 1,000°C in synthetic air. First, the isothermal thermogravimetric curves of both stainless steels were plotted to determine the time needed to reach the breakdown point. The different resistance of each stainless steel was interpreted on the basis of the nature of the crystalline phases formed, the morphology, and the surface structure as well as the cross-section structure of the oxidation products. The weight gain of AISI 304 stainless steel was about 8 times greater than that of AISI 316 stainless steel, and AISI 316 stainless steel reached the breakdown point about 40 times more slowly than AISI 304 stainless steel. In both stainless steels, reaching the breakdown point meant the loss of the protective oxide scale of Cr2O3, but whereas in AISI 304 stainless steel the Cr2O3scale totally disappeared and exclusively Fe2O3was formed, in AISI 316 stainless steel some Cr2O3persisted and Fe3O4was mainly formed, which means that AISI 316 stainless steel is more resistant to oxidation after the breakdown.

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