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.

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.

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.

Experimental investigation and empirical modeling for corrosion rate prediction of biodegradable zinc based composite considering the effect of constituent materials

2021 ◽  
pp. 095440622110556
Author(s):  
Dayanidhi Krishana Pathak ◽  
Pulak Mohan Pandey
Keyword(s):  
Mechanical Properties ◽  
Corrosion Rate ◽  
Biomedical Applications ◽  
Microwave Sintering ◽  
Research Work ◽  
Simulated Body Fluid Solution ◽  
Corrosion Current ◽  
Essential Elements ◽  
Empirical Modeling ◽  
Corrosion Properties

Biodegradable zinc (Zn) has shown great potential in the area of biomedical applications. Though, the mechanical properties are decisive for the use of Zn for orthopedic and cardiovascular applications. Consequently, one needs to focus on improving the mechanical properties of Zn for its suitability in biomedical applications. Alloying of essential elements of the human body resulted in enhancement of Zn’s mechanical properties in recent years. The corrosion rate of pure Zn is ideal; however, the addition of other elements has resulted in a loss of its ideal corrosion rate. The inclusion of hydroxyapatite (HA) and iron (Fe) in Zn has also been reported in improving the mechanical properties. Hence, a need is raised for the development of a model which can predict the corrosion rate after adding HA along with Fe in Zn. In this research work, empirical based modeling is proposed to predict the corrosion rate, which incorporates the outcome of addition of Fe and HA in Zn. The Zn based materials were fabricated with the help of microwave sintering for developing the empirical model. The corrosion properties of the materials were assessed through a potentiodynamic polarization test in a simulated body fluid solution. The enhanced corrosion rate was attained with the rise in HA (wt%) and Fe (wt%) in Zn. An empirical correlation was established between the influencing controlling parameters (i.e., corrosion current, equivalent weight, and material density) of corrosion rate. Confirmation experiments were conducted to validate the developed model, and the highest error of 6.12% was obtained between the experimental and predicted values exhibiting the efficaciousness of the proposed model.

CNT as Interconnects

2020 ◽  
pp. 130-159
Author(s):  
Karmjit Singh Sandha
Keyword(s):  
Comparative Analysis ◽  
Equivalent Circuit ◽  
Integrated Circuit ◽  
Equivalent Circuit Model ◽  
Global Level ◽  
Electrical Equivalent Circuit ◽  
Swcnt Bundle ◽  
Impedance Parameters ◽  
Power Delay Product ◽  
Technology Nodes

The chapter will start with brief introduction to the interconnects and its importance in an integrated circuit at deep sub-micron technology nodes. The brief discussion about the concept of scaling, interconnects models, and material in use are presented. The limitations of conventional materials at scaled down technology nodes will be discussed next. The focus of the chapter is to present the electrical equivalent circuit model to estimate the impedance parameters of SWCNT bundle and MWCNT bundle as interconnects at different nano-scaled technology nodes for global level interconnect length. Using ESC model of SWCNT, MWCNT, and copper, the performance comparative analysis for delay and power delay product (PDP) will be presented for different interconnect lengths at nano-scaled technology nodes. Finally, the chapter summary and conclusion will be written at the end of the chapter.

scholarly journals Study of the inhibitory ability of inorganic di- and polyphosphate compositions

2020 ◽  
Vol 315 ◽  
pp. 04002
Author(s):  
Aktoty Niyazbekova ◽  
Timur Shakirov ◽  
Mayra Almagambetova
Keyword(s):  
Experimental Data ◽  
Kinetic Data ◽  
Research Work ◽  
Corrosion Process ◽  
Degree Of Protection ◽  
Inhibitory Ability ◽  
Depth Index ◽  
Corrosion Deposits ◽  
The Stability ◽  
Quantitative Indicators

The article considers the anticorrosive properties of inorganic di-and polyphosphate compositions in relation to St-3 steel, depending on the pH of the medium, the nature and concentration of phosphate, and the nature of the modifier ion. The research was conducted using GOST-based methods: gravimetry, potentiometry, photocolorimetry, infrared spectroscopy and scanning electron microscopy. On the basis of experimental data, quantitative indicators of corrosion process were determined: the rate of corrosion process, the degree of protection, the depth index, the coefficient of inhibition and the assessment of the stability of the formed film on the ball scale of corrosion resistance against steel. The analysis of experimental data allows to establish the influence of the above factors on the corrosion processes in the systems under study. The experimental data are supplemented by thermodynamic calculations of the corrosion process parameters, the results of which correlate well with the kinetic data of the process under study. In the course of the research work, the analysis of corrosion deposits was also carried out. The regularities established during the work contribute to the creation of effective di-and polyphosphate inhibitors with the highest degrees of protection.

Electrochemical Characteristics of Lanthanum Hexaboride in the Environments Containing S2-

2010 ◽  
Vol 663-665 ◽  
pp. 473-476
Author(s):  
Shu Qi Zheng ◽  
Chang Feng Chen ◽  
Rui Jing Jiang ◽  
Dan Ni Wang
Keyword(s):  
Partial Pressure ◽  
Corrosion Behavior ◽  
Current Density ◽  
Corrosion Current Density ◽  
Corrosion Potential ◽  
Corrosion Current ◽  
Lanthanum Hexaboride ◽  
Electrochemical Characteristics

In the environment with H2S/CO2 or Na2S, the corrosion behavior of Lanthanum hexaboride (LaB6) was investigated by electrochemistry methods. The results indicated that the corrosion potential (Ecorr) and Rf of LaB6 increased as the partial pressure of H2S increased, while the corrosion current density (Icorr) decreased. In the environment containing Na2S, as the content of Na2S increased, the corrosion potential (Ecorr) and Rf of LaB6 decreased, while the corrosion current density (Icorr) increased. Thus, the addition of H2S into the environment with H2S/CO2 would inhibit the corrosion of LaB6; while in the environment containing Na2S, the increasing of the content of Na2S would accelerate the corrosion of LaB6.

Sign in / Sign up

Export Citation Format

Share Document