The Influence of the Semiconducting Properties of Passive Films on Localized Corrosion Rates

2019 ◽  
Vol 16 (52) ◽  
pp. 117-123 ◽  
Author(s):  
Scott P. Harrington ◽  
Thomas Devine
Keyword(s):  
Passive Films ◽  
Localized Corrosion ◽  
Corrosion Rates ◽  
Semiconducting Properties

Localized Corrosion of Binary Mg-Nd Alloys in Chloride-Containing Electrolyte Using a Scanning Vibrating Electrode Technique

CORROSION ◽  
2012 ◽  
Vol 68 (6) ◽  
pp. 489-498 ◽  
Author(s):  
G. Williams ◽  
K. Gusieva ◽  
N. Birbilis
Keyword(s):  
Localized Corrosion ◽  
Radial Expansion ◽  
Alloying Additions ◽  
Corrosion Rates ◽  
Surface Breakdown ◽  
Density Values ◽  
Intact Surface ◽  
Mean Current ◽  
Electrode Technique

The influence of neodymium (Nd) alloying additions in the 0.47 wt% to 3.53 wt% range on the localized corrosion behavior of Mg, when freely corroding in aqueous sodium chloride (NaCl) electrolyte, is investigated using an in situ scanning vibrating electrode technique (SVET). For all samples, the point of surface breakdown is an intense focal anode that expands radially with respect to time, revealing a cathodically activated interior, which is galvanically coupled with the local anode at the perimeter. However, for Nd compositions of ≤0.74%, radial expansion ceases within ca. 2 h of initiation, whereupon dark filiform-like corrosion features are observed, which traverse over the exposed Mg surface. For Nd additions of ≥1.25%, the radial expansion continues with time up to a point where the entire intact surface becomes consumed. The intensity of the local anode ring of circular corroded regions is seen to increase as more cathodically activated corroded surface becomes exposed. Mean current density values measured within these corroded areas increase progressively with Nd content, leading to a progressive rise in localized corrosion rates. The cathodic activation of corroded regions is proposed to derive from an enrichment of noble, Nd-rich intermetallic grains caused as the alpha-Mg phase becomes attacked at local anode sites.

The Corrosion of Carbon Steel and Stainless Steel in Simulated Geothermal Media

1985 ◽  
Vol 38 (8) ◽  
pp. 1133 ◽  
Author(s):  
BG Pound ◽  
MH Abdurrahman ◽  
MP Glucina ◽  
GA Wright ◽  
RM Sharp
Keyword(s):  
Carbon Steel ◽  
Corrosion Rate ◽  
Stainless Steels ◽  
Polarization Resistance ◽  
Iron Sulfide ◽  
Low Carbon Steel ◽  
Passive Films ◽  
Low Carbon ◽  
Corrosion Rates ◽  
Good Agreement

The corrosion rates of low-carbon steel, and 304, 316 and 410/420 stainless steels in simulated geothermal media containing hydrogen sulfide have been measured by means of the polarization resistance technique. Good agreement was found between weight-loss and polarization resistance measurements of the corrosion rate for all the metals tested. Carbon steel formed a non-adherent film of mackinawite (Fe1 + xS). The lack of protection afforded to the steel by the film resulted in an approximately constant corrosion rate. The stainless steels also exhibited corrosion rates that were independent of time. However, the 410 and 420 alloys formed an adherent film consisting mainly of troilite ( FeS ) which provided only limited passivity. In contrast, the 304 and 316 alloys appeared to be essentially protected by a passive film which did not seem to involve an iron sulfide phase. However, all the stainless steels, particularly the 410 and 420 alloys, showed pitting, which indicated that some breakdown of the passive films occurred.

Improvement of corrosion resistance of magnesium alloys for biomedical applications

2015 ◽  
Vol 33 (3-4) ◽  
pp. 101-117 ◽  
Author(s):  
Kai Chen ◽  
Jianwei Dai ◽  
Xiaobo Zhang
Keyword(s):  
Corrosion Resistance ◽  
Corrosion Behavior ◽  
Biomedical Applications ◽  
Mg Alloys ◽  
Localized Corrosion ◽  
Biodegradable Implants ◽  
Ordered Structure ◽  
Corrosion Rates ◽  
Long Period ◽  
Treatment Techniques

AbstractIn recent years, magnesium (Mg) alloys have attracted great attention due to superior biocompatibility, biodegradability, and other characteristics important for use in biodegradable implants. However, the development of Mg alloys for clinical application continues to be hindered by high corrosion rates and localized corrosion modes, both of which are detrimental to the mechanical integrity of a load-bearing temporary implant. To overcome these challenges, technologies have been developed to improve the corrosion resistance of Mg alloys, among which surface treatment is the most common way to enhance not only the corrosion resistance, but also the bioactivity of biodegradable Mg alloys. Nevertheless, surface treatments are unable to fundamentally solve the problems of fast corrosion rate and localized corrosion. Therefore, it is of great importance to alter and improve the intrinsic corrosion behavior of Mg alloys for biomedical applications. To show the significance of the intrinsic corrosion resistance of biodegradable Mg alloys and attract much attention on this issue, this article presents a review of the improvements made to enhance intrinsic corrosion resistance of Mg alloys in recent years through the design and preparation of the Mg alloys, including purifying, alloying, grain refinement, and heat treatment techniques. The influence of long-period stacking-ordered structure on corrosion behavior of the biodegradable Mg alloys is also discussed.

scholarly journals Semiconducting properties of oxide films formed onto an Nb electrode in NaOH solutions

2008 ◽  
Vol 73 (3) ◽  
pp. 351-367 ◽  
Author(s):  
Vladimir Jovic ◽  
Borka Jovic
Keyword(s):  
Space Charge ◽  
Oxide Films ◽  
Passive Films ◽  
Flat Band ◽  
Potential Range ◽  
Donor Density ◽  
Nano Crystalline ◽  
Semiconducting Properties ◽  
Eis Measurements ◽  
Charge Capacitance

In this paper, the results of the potentiostatic formation of homogeneous and heterogeneous, nano-crystalline passive films of Nb2O5 onto an Nb electrode in NaOH solutions of different concentrations at potentials lower than 3.0 V vs. SCE are presented. The semiconducting properties of such films were investigated by EIS measurements. After fitting the EIS results by appropriate equivalent circuits, the space charge capacitance (Csc) and space charge resistance (Rsc) of these films were determined. The donor density (Nsc), flat band potential (Efb) and thickness of the space charge layer (dsc) for such oxide films were determined from the corresponding Mott-Schottky (M-S) plots. It is shown that all oxide films were n-type semiconductors in a certain potential range.

Corrosion Behavior of TP95S Anti-Sulfur Casing Steel in High Temperature High Pressure H2S/CO2 Environment

2011 ◽  
Vol 335-336 ◽  
pp. 506-510
Author(s):  
Bin Wang ◽  
Dong Mei Zhou ◽  
Jiang Hu Bai
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Localized Corrosion ◽  
Corrosion Performance ◽  
The Core ◽  
Corrosion Rates ◽  
Simulated Environments ◽  
Static Conditions ◽  
High Temperature High Pressure ◽  
Static Corrosion

The anti-corrosion performance of Tiangang TP95S casing steel was studied by high temperature autoclaves simulating the high-temperature and high-pressure H2S/CO2 environment. The experimental results show that the corrosion rates increase with the rising of temperature which is from 40°C to 80°C under the dynamic and static conditions of the simulated environments; the dynamic corrosion rates are between 1.7294 and 1.8601mm/a and the corrosion rates are 0.4264～1.2715mm/a under the static conditions, both of which belong to a serious corrosion category; the dynamic corrosion samples have had the localized corrosion at 40°C, but the local corrosion of the static corrosion specimens appeared at 80°C; the corrosion product of TP95S steel takes FeS as the core in the case of static corrosion at 40°C.

Sign in / Sign up

Export Citation Format

Share Document