Current Density Effects on the Corrosion of Ceramic and Metallic Electrode Materials in Waste Glasses

1995 ◽  
Vol 412 ◽  
Author(s):  
E. Wang ◽  
R. K. Mohr ◽  
A. C. Buechele ◽  
I. L. Pegg
Keyword(s):  
Corrosion Rate ◽  
Current Density ◽  
Electrode Materials ◽  
Corrosion Process ◽  
Metallic Electrode ◽  
Electrode Current ◽  
Waste Vitrification ◽  
Inconel 690 ◽  
Lower Temperature ◽  
High Level

AbstractVitrification by joule-heating requires suitable electrode materials. Molybdenum electrodes are used often in high temperature (∼1500°C) joule-heated melters producing commercial glass while Inconel 690 has been the material of choice for lower temperature (∼1150°C) high-level nuclear waste vitrification. Vitrification of diverse waste streams at higher-temperatures places increasingly severe demands upon the electrode materials. Some commercially available ceramics possess sufficient conductivity at high temperatures to be used as electrodes. Many mixed- and low-level waste vitrification applications involve significant amounts of reducible species that accelerate the corrosion process for metallic electrodes. In addition, the corrosion rate of all electrode materials depends on the electrode current density. A special test rig was designed that measures the dependence of corrosion rate on both current density and temperature over extended periods of time. Molybdenum, Inconel 690, and three types of commercial ceramic coupons were tested over a range of conditions in simulated waste glasses containing key reducible species (e.g., PbO, CuO, ZnO, SO3). The corrosion rates show strong dependencies on the current density. Coupons were sectioned and the glass-coupon interface examined using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS). Cu, Pb, Ni and Sn were found to be reduced to their metallic states at the molybdenum coupon surfaces and were active in the corrosion process.

Corrosion of inconel-690 electrodes in waste glass melts

1999 ◽  
Vol 556 ◽  
Author(s):  
H. Gan ◽  
A. C. Buechele ◽  
C.-W. Kim ◽  
X. Huang ◽  
R. K. Mohr ◽  
...  
Keyword(s):  
Nuclear Waste ◽  
Glass Composition ◽  
Waste Glass ◽  
Savannah River ◽  
Glass Melts ◽  
Waste Vitrification ◽  
Inconel 690 ◽  
Ac Current ◽  
High Level Nuclear Waste ◽  
High Level

AbstractInconel-690, a Cr-Ni-Fe-based “superalloy,” has become the material of choice for electrodes in joule-heated waste glass melters and is currently employed in the high-level nuclear waste vitrification systems at West Valley and DWPF, as well as in GTS Duratek's privatized M-Area mixed waste vitrification facility at Savannah River. Future applications of joule-heated vitrification technologies will necessitate an assessment of the limits of performance of this material under more demanding conditions than have been studied previously. In this work, Inconel 690 electrodes were tested in several simulated sodium-rich aluminosilicate waste glasses in wide ranges of AC current density, electrical waveform, temperature, and glass composition.

Discussion on AC Corrosion Rate Assessment and Mechanism for Cathodically Protected Pipelines

CORROSION ◽  
10.5006/3561 ◽  
2021 ◽  
Author(s):  
Yanxia Du ◽  
Yi Liang ◽  
Dezhi Tang ◽  
Sili Xie
Keyword(s):  
Corrosion Rate ◽  
Current Density ◽  
Research Work ◽  
Equivalent Circuit Model ◽  
Local Environment ◽  
Corrosion Process ◽  
Electrochemical Characteristics ◽  
Electrical Equivalent Circuit ◽  
Corrosion Failure ◽  
Interface Dynamic

Although a lot of AC corrosion failure cases and research work on cathodically protected pipelines have been reported, the mechanism of AC corrosion process has not been completely understood and there still exist many debates on AC corrosion assessment criteria under cathodic protection (CP), especially under high CP level. The AC corrosion simulation experiments in three kinds of environments were conducted to study the AC corrosion behavior under different conditions. Based on AC corrosion rates and corresponding AC current density, DC IR-free potential and DC current density, the AC corrosion rate assessment diagrams were obtained and the threshold values for AC and DC parameters were proposed. Besides, the AC corrosion morphologies, products, local environment parameters and electrochemical characteristics were measured and analyzed under the combined effects of AC and CP. The effect of hydrogen evolution reaction on AC corrosion process under high CP level was discussed based on the electrical equivalent circuit model at the steel/electrolyte interface, dynamic electrochemical reaction process and the change of local environment close to the specimen surface.

scholarly journals A Hierarchical Architecture of Functionalized Polyaniline/Manganese Dioxide Composite with Stable-Enhanced Electrochemical Performance

2021 ◽  
Vol 5 (5) ◽  
pp. 129
Author(s):  
Yapeng Wang ◽  
Yanxiang Wang ◽  
Chengjuan Wang ◽  
Yongbo Wang
Keyword(s):  
Electrochemical Performance ◽  
Manganese Dioxide ◽  
Specific Capacitance ◽  
Current Density ◽  
Electrode Materials ◽  
High Efficiency ◽  
Scanning Speed ◽  
Hierarchical Architecture ◽  
Electrochemical Window ◽  
A Current

As one of the most outstanding high-efficiency and environmentally friendly energy storage devices, the supercapacitor has received extensive attention across the world. As a member of transition metal oxides widely used in electrode materials, manganese dioxide (MnO2) has a huge development potential due to its excellent theoretical capacitance value and large electrochemical window. In this paper, MnO2 was prepared at different temperatures by a liquid phase precipitation method, and polyaniline/manganese dioxide (PANI/MnO2) composite materials were further prepared in a MnO2 suspension. MnO2 and PANI/MnO2 synthesized at a temperature of 40 °C exhibit the best electrochemical performance. The specific capacitance of the sample MnO2-40 is 254.9 F/g at a scanning speed of 5 mV/s and the specific capacitance is 241.6 F/g at a current density of 1 A/g. The specific capacitance value of the sample PANI/MnO2-40 is 323.7 F/g at a scanning speed of 5 mV/s, and the specific capacitance is 291.7 F/g at a current density of 1 A/g, and both of them are higher than the specific capacitance value of MnO2. This is because the δ-MnO2 synthesized at 40 °C has a layered structure, which has a large specific surface area and can accommodate enough electrolyte ions to participate the electrochemical reaction, thus providing sufficient specific capacitance.

scholarly journals Biodegradable Iron-Based Materials—What Was Done and What More Can Be Done?

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3381
Author(s):  
Gabriela Gąsior ◽  
Jonasz Szczepański ◽  
Aleksandra Radtke
Keyword(s):  
Corrosion Rate ◽  
Iron Metabolism ◽  
Elastic Moduli ◽  
High Strength ◽  
Corrosion Process ◽  
Basic Data ◽  
Metal Stents ◽  
Biodegradable Metal ◽  
Iron Based

Iron, while attracting less attention than magnesium and zinc, is still one of the best candidates for biodegradable metal stents thanks its biocompatibility, great elastic moduli and high strength. Due to the low corrosion rate, and thus slow biodegradation, iron stents have still not been put into use. While these problems have still not been fully resolved, many studies have been published that propose different approaches to the issues. This brief overview report summarises the latest developments in the field of biodegradable iron-based stents and presents some techniques that can accelerate their biocorrosion rate. Basic data related to iron metabolism and its biocompatibility, the mechanism of the corrosion process, as well as a critical look at the rate of degradation of iron-based systems obtained by several different methods are included. All this illustrates as the title says, what was done within the topic of biodegradable iron-based materials and what more can be done.

scholarly journals Evaluation of possible corrosion enhancement due to telluric currents: case study of the Bolivia–Brazil pipeline

2020 ◽  
Vol 38 (4) ◽  
pp. 881-888
Author(s):  
Joyrles Fernandes de Moraes ◽  
Igo Paulino ◽  
Lívia R. Alves ◽  
Clezio Marcos Denardini
Keyword(s):  
Corrosion Rate ◽  
Space Weather ◽  
Geomagnetic Storms ◽  
Corrosion Process ◽  
Fluxgate Magnetometer ◽  
Weather Events ◽  
Source Line ◽  
Geomagnetic Data ◽  
Telluric Currents

Abstract. The electric field induced in the Bolivia–Brazil gas pipeline (GASBOL) was calculated by using the distributed source line transmission (DSLT) theory during several space weather events. We used geomagnetic data collected by a fluxgate magnetometer located at São José dos Campos (23.2∘ S, 45.9∘ W). The total corrosion rate was calculated by using the Gummow (2002) methodology and was based on the assumption of a 1 cm hole in the coating of the pipeline. The calculations were performed at the ends of pipeline where the largest “out-of-phase” pipe-to-soil potential (PSP) variations were obtained. The variations in PSP during the 17 March 2015 geomagnetic storm have led to the greatest corrosion rate of the analyzed events. All the space weather events evaluated with high terminating impedance may have contributed to increases in the corrosion process. The applied technique can be used to evaluate the corrosion rate due to the high telluric activity associated with the geomagnetic storms at specific locations.

Different Chilling-Induced Symptoms and the Underlying Oxidative Stress and Antioxidative Defense in the Exocarp and Mesocarp of Immature Sponge Gourd (Luffa cylindrica) Fruit

2021 ◽  
Author(s):  
Pichaya Chuenchom ◽  
Sompoch Noichinda ◽  
Kitti Bodhipadma ◽  
Chalermchai Wongs-Aree ◽  
David W. M. Leung
Keyword(s):  
Oxidative Stress ◽  
Defense Mechanisms ◽  
Considerable Increase ◽  
Chilling Injury ◽  
Oxygen Species ◽  
Antioxidative Defense ◽  
Sponge Gourd ◽  
Lower Temperature ◽  
High Level ◽  
The Relationship

Immature sponge gourd fruit is consumed as a vegetable with a limited shelf life. Although cold storage is a simple and powerful tool for maintaining postharvest fruit quality, storage at a low temperature may not be appropriate for vegetables as some chilling injury (CI) of the immature sponge gourd fruit may occur. Therefore, this research aimed to elucidate the relationship between CI, oxidative stress, and the antioxidative defense mechanisms in the exocarp and mesocarp of immature sponge gourd fruit. After storage at 5°C for 6 days, visual CI symptoms, including browning and surface pitting, were found in the peel (exocarp) but not in the mesocarp. There were, however, more dead cells (stained by Evans blue) in the mesocarp of the fruit stored at 5°C. There was a more considerable increase in the electrolyte leakage rate in both fruit tissues held at 5°C than 25°C. The CI was correlated with malondialdehyde (MDA) levels in the tissues. The MDA of fruit exocarp at 5°C was 1.6 fold higher than that at 25°C on day 6, while the lipoxygenase (LOX) activity in mesocarp was 50% higher in fruit stored at a lower temperature. The action of ascorbate peroxidase (APX) was high in the exocarp of the fruit stored at 5°C, but there appeared to be a continuous depletion of the co-substrate or ascorbic acid. In conclusion, the CI in the exocarp was mainly associated with a high level of reactive oxygen species (ROS). In contrast, the CI in the mesocarp appeared to be primarily associated with increased lipid peroxidation by the elevated LOX activity under cold stress compared to storage at 25°C.

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