Download or read book Electrochemical Study of Corrosion Phenomena in Zirconium Alloys written by Nicole M. Treeman and published by . This book was released on 2005 with total page 135 pages. Available in PDF, EPUB and Kindle. Book excerpt: (cont.) In this thesis research, four electrode pairs were used to measure galvanic current densities in the irradiation environment: Pt-Pt, Zircaloy 2 (Zr-2)-Pt, Inconel (X-750)-Pt, and Zr-2-X-750. To determine the changes in the coolant water conductivity due to the presence of radiolysis products, electrochemical potential measurements of Pt-Pt coupled electrodes were analyzed. Finally, attempts to characterize the observed oxide behavior using measurements from Electrochemical Impedance Spectroscopy (EIS), also known as Alternating Current Impedance, were conducted. Through the measurements taken, analysis of the mechanisms potentially causing the shadow corrosion phenomenon was conducted. The results of the observations included: -- Measurement of increased conductivity of coolant water correlating to increases in reactor power. -- Measurement of increased galvanic current measurements correlating to increases in reactor power.

Download or read book Progress in Corrosion Science and Engineering II written by Su-Il Pyun and published by Springer Science & Business Media. This book was released on 2012-02-09 with total page 349 pages. Available in PDF, EPUB and Kindle. Book excerpt: This and volume no. 47 of Modern Aspects of Electrochemistry is composed of eight chapters covering topics having relevance both in corrosion science and materials engineering. In particular, the first seven chapters provide comprehensive coverage of recent advances in corrosion science.

Download or read book Corrosion Behaviour of Zirconium Alloys in High Temperature Aqueous Environment by Electrochemical Impedance Spectroscopy written by Peng Wang and published by . This book was released on 2011 with total page 217 pages. Available in PDF, EPUB and Kindle. Book excerpt: The corrosion behaviour of zirconium based alloys has been primarily investigated by electrochemical impedance spectroscopy (EIS). In-situ autoclave EIS experiments were performed in simulated primary coolant conditions in order to study the high temperature water corrosion of zirconium alloys in PWRs. In-situ impedance response of the corroding material was recorded throughout first kinetic transition. A physical model of the zirconium oxide was proposed in accordance with the microstructural observation' made by SEM analysis. Electrical properties of the oxide was evaluated with equivalent circuit model (ECM) which was constructed according to the physical oxide model. Evolution of various oxide parameters obtained from ECM was analysed in accordance with the microstructure observation made by SEM. A two layer structure consists of a outer porous oxide and an inner barrier oxide, was found to be the most accurate description for the autoclave formed oxide. Supporting evidence from the SEM cross-section and surface analysis of the oxide had shown cracks and pores that were linked and connected with the environment. This observation is also confirmed by the in-situ EIS measurement which has shown porous electrode behaviour throughout the course of oxidation. The porous oxide behaviour was also confirmed by the ex-situ soaking experiment on samples with incremental exposure time. Evolution of inner barrier layer oxide thickness was found to be correlated with kinetic transition which was determined from weight gain measurement. This indicated that barrier layer maybe the oxidation rate controlling layer and its thickness maybe reduced during transition. Thus, a thinner barrier layer would resulted in a rapid corrosion of zirconium alloys. Furthermore, maintaining the barrier layer thickness maybe the possible route to improve zirconium alloy corrosion resistance.

Download or read book Electrochemical Techniques in Corrosion Science and Engineering written by Robert G. Kelly and published by CRC Press. This book was released on 2002-09-13 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the origin, use, and limitations of electrochemical phase diagrams, testing schemes for active, passive, and localized corrosion, the development and electrochemical characterization of passivity, and methods in process alteration, failure prediction, and materials selection. It offers useful guidelines for assessing the efficac

Download or read book Electrochemical and Optical Techniques for the Study and Monitoring of Metallic Corrosion written by M.G.S Ferreira and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 714 pages. Available in PDF, EPUB and Kindle. Book excerpt: In spite of considerable efforts over the years to understand and combat materials degradation via corrosion processes, many challenges still remain both in the theoretical understanding of the phenomena and in seeking pratical solutions to the perennial problem. Progress has been slow due to the complexity of the processes and the systems involved. Fortunately, in recent years there has been a renaissance in the development of new electrochemical and optical techniques, as well as advances in instrumentation, which have greatly aided our quest to gain insight into the complex mechanisms involved in metallic corrosion and passivation. Numerous scientific meetings, symposia, and workshops have been held allover the world which attest to the frenzy of activities in corrosion science and technology. However, most of these conferences have dealt mainly with recent research results. There appeared to be a need to assess and disseminate our present state of knowledge in the field as regards measurement techniques, theory, and instrumentation. The present NATO Advanced Study Institute was therefore held in Viana do Castelo, Portugal from July 9 to 21, 1989. The Institute consisted of a series of tutorial lectures, poster sessions, and round-table discussions interspersed evenly over the two-week period. It was attended by 75 participants from several countries representing industry, government and university laboratories.

Download or read book Electrochemical Studies of Mobile Charged Species During Zirconium Alloy Oxidation written by James Stephen Smith and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This research has used a suite of electrochemical techniques, both in-situ and ex-situ to investigate the mobile charged species in the oxides of zirconium alloys. Limits on the corrosion resistance of existing zirconium alloys used for fuel cladding are a major restriction on the burn-up that can be achieved within a pressurised water reactor (PWR). Developing a full mechanistic understanding of the corrosion process of zirconium alloys in the primary water environment is necessary for prolonging the life-time of fuel cladding. A key component in the corrosion of zirconium alloy is the transport properties of various charged species within the oxide layer, which determine the rate of corrosion. Three distinct electrochemical methods have been employed in this work. The first technique, Electrochemical Impedance Spectroscopy (EIS), has been used to determine the physical properties of the oxide. The second technique, Mott-Schottky analysis, studied the oxide acceptor/donor densities; hence the nature, concentration and activation energy of the major electronic charge carrier could be determined. The final method, a DC method known as Wagner-asymmetric polarization (WAP), separated the ionic and electronic currents and can thus allow the calculation of transport numbers, partial conductivities and activation energies of the ionic species. All the techniques investigated parameters as a function of oxidation time, lithium concentration and alloying elements. Work was carried out on oxides grown under PWR conditions (2 ppm Li and 1000 ppm B) at temperatures of 240-360 °C on specimens of zircaloy-4, ZIRLO, Zr-0.1%Nb and Zr-1%Nb. The EIS was undertaken in-situ to determine the oxide thickness and showed that the electrochemically active oxide grows quicker in a higher lithium concentration. Variances in oxide growth rates are also seen between specimens of differing niobium and tin content. In-situ Mott-Schottky analysis of the electronic charge carriers within the thin oxide showed the oxide to be a n-type semiconductor. Hence the dominant charge carriers, for early stage oxidation of Zircaloy-4 under simulated PWR conditions, were electrons with a donor density of approximately 2 x 1017 cm-3. The addition of lithium to the oxidation environment increases the donor density, which indicates lithium plays a previously unknown active role in the corrosion process. Despite the oxide being highly resistive, this research has also shown that the ionic charge carriers within the oxide can be directly measured using asymmetric-polarisation. However, further work needs to be undertaken to perfect this technique under inert atmospheres.

Download or read book Towards Impacting Electrochemical Phenomena Using Interfacial Engineering written by Sami Khan (Ph. D.) and published by . This book was released on 2020 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical phenomena can be broadly defined as any process that involves transfer of electrons, concurrently with a measurable and quantifiable chemical change. Interfacial engineering, on the other hand, can be defined as the altering of surface chemistry and texture across various length scales to impact electro-chemo-mechanical interactions between two or more surfaces. In this thesis, the role of interfacial engineering in impacting two specific electrochemical phenomena has been studied: corrosion and electrochemical reduction of CO 2 In the first part of this thesis, lubricant-impregnated surfaces (LISs) consisting of thin films of lubricant held stably in micro-textures by means of capillary forces have been systematically designed and studied for reducing corrosion. Corrosion is a detrimental process that can impact the performance and lifetime of many infrastructural systems and structures. In this work, we fabricate microposts on silicon using photolithography, varying inter-post spacing systematically from 5 pm to 50 pm, and conformally sputter coat a thin layer of iron to study the corrosion phenomena electrochemically in an aqueous 3.5 wt% sodium chloride solution, and we show that the corrosion rate on LIS is drastically reduced by three orders of magnitude. Using electrochemical impedance spectroscopy, we develop model circuits for various LIS configurations and show that the measured resistances and capacitances agree with a theoretical model, and discuss in detail where deviations may occur. Similarly, we study the role of lubricant layers towards reducing hydrogen embrittlement. Using a Devanathan-Stachurski electrochemical permeation cell we show that under accelerated conditions, the effective diffusion coefficient of hydrogen on steel is reduced by an order of magnitude using LIS. Furthermore, we apply LIS to heal zirconia coatings on steel. Zirconia, that grows natively on zirconium alloys used as cladding for fuel in nuclear reactors, is known to serve as a hydrogen barrier but the presence of grain boundaries or macroscopic surface defects can provide pathways for hydrogen entry. We show that LIS improves the effective diffusion coefficient of a defective zirconia film on steel by an order of magnitude. Finally, we develop aerophilic surfaces to trap CO2 bubbles in close proximity to a CO2 electro-reduction catalyst. Electrochemical reduction of CO2 (CO2RR) to valuable fuels is a promising approach towards reducing the ever-growing atmospheric CO2 levels, and efficient delivery and replenishment of CO2 remains a fundamental challenge that can impact CO 2RR current density and product distribution. When CO2 bubbles are trapped near the catalyst in a plastron layer, the local co 2 concentration available to the catalyst is enhanced and maintained, thereby increasing the magnitude of current density associated with CO2 reduction by close to two times as compared to the conventional CO2 heads pace mode of delivery. We confirm the enhancement in local CO2 concentration using sensitive pH probes as well as colorimetric techniques. Furthermore, we find that hydrogen co-evolution is suppressed from 33% in the heads pace case to 13% with the plastron at -1.1 V vs RHE. We demonstrate that the increase in the CO2RR current density can be scaled up to an array of copper catalysts that possess a higher surface area, while maintaining current density and CO2 concentration close to the catalyst for over an hour. We also demonstrate that CO2RR performance can be enhanced on a porous, nano-structured catalyst using these plastron layers.

Download or read book Lectures on Electrochemical Corrosion written by Marcel Pourbaix and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Workers in the field of corrosion and their students are most fortunate that a happy set of circumstances brought Dr. Marcel Pourbaix into their field in 1949. First, he was invited, while in the USA, to demonstrate at a two week visit to the National Bureau of Standards the usefulness of his electro chemical concepts to the study of corrosion. Secondly, also around the same time, Prof. H. H. Uhlig made a speech before the United Nations which pointed out the tremendous economic consequences of corrosion. Because of these circumstances, Dr. Pourbaix has reminisced, he chose to devote most of his efforts to corrosion rather than to electrolysis, batteries, geology, or any of the other fields where, one might add, they were equally valuable. This decision resulted in his establishing CEBELCOR (Centre BeIge d'Etude de la Corrosion) and in his development of a course at the Free University of Brussels entitled "Lectures on Electrochemical Corrosion." This book is the collection of these lectures translated into English.

Download or read book Zirconium in the Nuclear Industry written by R. B. Adamson and published by ASTM International. This book was released on 1987 with total page 832 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Correlation Between Electrochemical Properties and Corrosion Resistance of Zirconium Alloys written by T. Furuya and published by . This book was released on 1996 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The electrochemical behavior of some zirconium alloys including Zry-2 with various ?Ai from 2.5 x 10-20 to 1.2 x 10-17 (h), modified Zry-2 with iron contents of 0.15, 0.25, and 0.5%, and standard Zry-4 was studied by measuring anodic polarization curves in sulfuric acid solution. The results of these electrochemical tests were compared with those of steam autoclave tests.

Download or read book Progress Report on Electrochemical and Polarographic Studies on the Corrosion Or Zirconium in Presence of Various Aqueous Media written by Pierre Van Rysselberghe and published by . This book was released on 1953 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Hydrogen Evolution and Pickup During the Corrosion of Zirconium Alloys written by S. Yagnik and published by . This book was released on 2002 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electrochemical studies were performed in lithiated water (2.5 ppm Li and 1 ppm dissolved hydrogen) at 315°C in autoclave tests, on Zircaloy-2. Only the outside surface of the cladding was exposed to the environment. Specimens were corroded at open circuit potentials and also with externally imposed constant currents and potentials. The effects of weld regions and of a thin sputtered palladium coating on corrosion potential, the polarization behavior, and hydrogen pickup were investigated. Post-transition oxides were grown in steam at 12.5 MPa and 400°C, and electrochemical measurements were performed at 315°C in the lithiated water. The intrinsic electrochemical coupling effect, inherent in welding Zircaloy components, was also investigated in a loop test. Infrared interferometry and differential scanning calorimetry were used to measure the oxide thickness and hydrogen pickup along the specimen length.

Download or read book Hydrogen Entry in Zircaloy 4 Fuel Cladding written by Jennifer Anne Jarvis and published by . This book was released on 2015 with total page 318 pages. Available in PDF, EPUB and Kindle. Book excerpt: Corrosion and hydrogen pickup of zirconium alloy fuel cladding in water cooled nuclear reactors are life-limiting phenomena for fuel. This thesis studies the fate of hydrogen liberated by waterside corrosion of Zircaloy-4 fuel cladding in Pressurized Water Reactors (PWRs): are the adsorbed protons incorporated into the oxide and eventually the metal, or are they evolved into molecular hydrogen and released into the coolant? Water chemistry modeling was used to understand effects of radiolysis and CRUD. Density functional theory (DFT) was used to investigate the role of oxidized Zr(Fe,Cr)2 second phase particles. Chemical potentials and the electron chemical potential were used to connect these two modeling efforts. A radiolysis model was developed for the primary loop of a PWR. Dose profiles accounting for fuel burnup, boron addition, axial power profiles, and a CRUD layer were produced. Dose rates to the bulk coolant increased by 21-22% with 12.5-75 pim thick CRUD layers. Radially-averaged core chemistry was compared to single-channel chemistry at individual fuel rods. Calculations showed that local chemistry was more oxidizing at high-power fuel and fuel with CRUD. Local hydrogen peroxide concentrations were up to 2.5 ppb higher than average levels of 5-8 ppb. Radiolysis results were used to compute chemical potentials and the corrosion potential. Marcus theory was applied to compare the band energies of oxides associated with Zircaloy-4 and the energy levels for proton reduction in PWR conditions. Hydrogen interactions with Cr203 and Fe203, both found in oxidized precipitates, were studied with DFT. Atomic adsorption of hydrogen was modeled on the Cr and Feterminated (0001) surfaces. Climbing Image-Nudged Elastic Band calculations were used to model the competing pathways of hydrogen migration into the subsurface and molecular hydrogen formation. A two-step mechanism for hydrogen recombination was identified consisting of: reduction of an adsorbed proton (H+) to a hydride ion (H-) and H2 formation from an adjacent adsorbed proton and hydride ion. Overall, results suggest that neither surface will be an easy entrance point for hydrogen ingress and that Cr203 is more likely to be involved in hydrogen evolution than the Fe203.

Download or read book Comprehensive Nuclear Materials written by and published by Elsevier. This book was released on 2020-07-22 with total page 4871 pages. Available in PDF, EPUB and Kindle. Book excerpt: Materials in a nuclear environment are exposed to extreme conditions of radiation, temperature and/or corrosion, and in many cases the combination of these makes the material behavior very different from conventional materials. This is evident for the four major technological challenges the nuclear technology domain is facing currently: (i) long-term operation of existing Generation II nuclear power plants, (ii) the design of the next generation reactors (Generation IV), (iii) the construction of the ITER fusion reactor in Cadarache (France), (iv) and the intermediate and final disposal of nuclear waste. In order to address these challenges, engineers and designers need to know the properties of a wide variety of materials under these conditions and to understand the underlying processes affecting changes in their behavior, in order to assess their performance and to determine the limits of operation. Comprehensive Nuclear Materials, Second Edition, Seven Volume Set provides broad ranging, validated summaries of all the major topics in the field of nuclear material research for fission as well as fusion reactor systems. Attention is given to the fundamental scientific aspects of nuclear materials: fuel and structural materials for fission reactors, waste materials, and materials for fusion reactors. The articles are written at a level that allows undergraduate students to understand the material, while providing active researchers with a ready reference resource of information. Most of the chapters from the first Edition have been revised and updated and a significant number of new topics are covered in completely new material. During the ten years between the two editions, the challenge for applications of nuclear materials has been significantly impacted by world events, public awareness, and technological innovation. Materials play a key role as enablers of new technologies, and we trust that this new edition of Comprehensive Nuclear Materials has captured the key recent developments. Critically reviews the major classes and functions of materials, supporting the selection, assessment, validation and engineering of materials in extreme nuclear environments Comprehensive resource for up-to-date and authoritative information which is not always available elsewhere, even in journals Provides an in-depth treatment of materials modeling and simulation, with a specific focus on nuclear issues Serves as an excellent entry point for students and researchers new to the field

Download or read book Studies Regarding Corrosion Mechanisms in Zirconium Alloys written by M. Preuss and published by . This book was released on 2011 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding the key corrosion mechanisms in a light water reactor primary water environment is critical to developing and exploiting improved zirconium alloy fuel cladding. In this paper, we report recent research highlights from a new collaborative research programme involving 3 U.K. universities and 5 partners from the nuclear industry. A major part of our strategy is to use the most advanced analytical tools to characterise the oxide and metal/oxide interface microstructure, residual stresses, as well as the transport properties of the oxide. These techniques include three-dimensional atom probe (3DAP), advanced transmission electron microscopy (TEM), synchrotron X-ray diffraction, Raman spectroscopy, and in situ electro-impedance spectroscopy. Synchrotron X-ray studies have enabled the characterisation of stresses, tetragonal phase fraction, and texture in the oxide as well as the stresses in the metal substrate. It was found that in the thick oxide (here, Optimized-ZIRLO, a trademark of the Westinghouse Electric Company, tested at 415°C in steam) a significant stress profile can be observed, which cannot be explained by metal substrate creep alone but that local delamination of the oxide layers due to crack formation must also play an important role. It was also found that the oxide stresses in the monoclinic and tetragonal phases grown on Zircaloy-4 (autoclave testing at 360°C) first relax during the pre-transition stage. Just before transition, the compressive stress in the monoclinic phase suddenly rises, which is interpreted as indirect evidence of significant tetragonal to monoclinic phase transformation taking place at this stage. TEM studies of pre- and post-transition oxides grown on ZIRLO, a trademark of the Westinghouse Electric Company, have used Fresnel contrast imaging to identify nano-sized pores along the columnar grain boundaries that form a network interconnected once the material goes through transition. The development of porosity during transition was further confirmed by in situ electrochemical impedance spectroscopy (EIS) studies. 3DAP analysis was used to identify a ZrO sub-oxide layer at the metal/oxide interface and to establish its three-dimensional morphology. It was possible to demonstrate that this sub-oxide structure develops with time and changes dramatically around transition. This observation was further confirmed by in situ EIS studies, which also suggest thinning of the sub-oxide/barrier layer around transition. Finally, 3DAP analysis was used to characterise segregation of alloying elements near the metal/oxide interface and to establish that the corroding metal near the interface (in this case ZIRLO) after 100 days at 360°C displays a substantially different chemistry and microstructure compared to the base alloy with Fe segregating to the Zr/ZrO interface.

Download or read book Summaries of the UDAEC Basic Research Programs in Metallurgy Solid State Physics and Ceramics written by R. J. Allio and published by . This book was released on 1961 with total page 274 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976-02 with total page 722 pages. Available in PDF, EPUB and Kindle. Book excerpt: