Download or read book The Importance of Oxide Morphology for the Oxidation Rate of Zirconium Alloys written by E. Ahlberg and published by . This book was released on 1996 with total page 19 pages. Available in PDF, EPUB and Kindle. Book excerpt: The oxide growth rate of zirconium alloys, e.g., Zircaloy-2 and Zircaloy-4, has been proposed to be controlled mainly by the transformation of the zirconium oxide from tetragonal to monoclinic structure at some distance from the metal-oxide interface, leading to cracking. This oxide growth rate model is inconsistent with our results. Zirconium alloys of varying chemical composition but with identical manufacturing process had markedly different oxide growth and hydriding properties in autoclave testing (400°C steam). The materials were characterized by several methods, e.g., electron microscopy (SEM), X-ray diffraction (XRD), and electrochemical impedance (EIS). The SEM and some of the XRD investigations of the oxide were performed on the metal-oxide interface after dissolution of the metal. The oxide growth developed through three different stages with an altered oxide morphology at the metaloxide interface at each stage. The developments of the stages were correlated with the oxide growth rate. Impedance measurements suggested that the oxide film had three layers, the outermost being extensively porous. Relaxation of the oxide film stress showed that the compressive stress in the oxide was not essential for retention of a significant amount of the tetragonal phase.

Download or read book Zirconium in the Nuclear Industry written by George P. Sabol and published by ASTM International. This book was released on 1996 with total page 907 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book An Investigation of the Effect of Tin on Zirconium Alloy Oxide Morphology written by Jessica Gee and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This study aims to investigate oxide formation in zirconium-tin binary alloys as compared to pure zirconium corroded in an oxygen environment. An analysis of oxide morphology with a focus on the metal-oxide interface is meant to establish the influence of tin content on the formation of instabilities in zirconium oxide, leading to breakaway corrosion. The oxide formed on three alloys of varying tin content are compared with those formed on zirconium crystal bar and zirconium sponge to characterize the role tin plays in altering the formation of oxide in these metals. Optical microscopy as well as field emission scanning electron microscopy (FESEM) imaging are used to observe the cross-sectional oxide growth. Increasing tin content increases the oxide thickness. The comparison between these alloys allows for the examination of stable, unstable, and breakaway oxide behavior. Preferential oxide growth occurs at grain boundaries, and develops into instabilities that permeate into grains within the metal. Breakaway behavior causes a dramatic increase in oxidation rate.

Download or read book Oxidation of Zirconium and Zirconium Alloys in Liquid Sodium written by T. L. Mackay and published by . This book was released on 1962 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Nature of Unstable Oxide Growth in Zirconium and Zirconium Alloys written by Brendan Ensor and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Zirconium alloys are commonly used as fuel claddings in nuclear reactors due in part to theirsuperior corrosion resistance. The addition of small concentrations of alloying elements prevents thecladding material from undergoing unstable oxide growth under the operating conditions of a nuclearreactor. Unstable oxide growth can also occur due to the presence of hydrides or exposure to neutron flux.The role of alloying elements in avoiding the transition from stable to unstable growth is examined in thisthesis. The goal is to determine the mechanism whereby oxide stabilization occurs.To accomplish this goal, a variety of experiments were performed, and the resulting oxide layerscharacterized with various techniques. Ten model Zr alloys were fabricated and tested in furnace at 600Cfor 40 hours in oxygen and in autoclave at 360C for up to 70 days to determine the causes of breakawayoxidation in pure Zr (and Zr alloys with small concentrations of alloying elements) and the role that alloyingelements play in causing this phenomenon. These alloys were carefully selected and included crystal barZr, sponge Zr, and alloys with small concentrations of Sn, Fe, and Cr. After testing, the alloys werecharacterized using scanning electron microscopy (SEM), Raman spectroscopy, and synchrotron -X-rayfluorescence (XRF) to determine how the structure of the oxide, tetragonal phase content, and alloyingelement distribution affected the formation of unstable oxide. Heterogeneous distribution of alloyingelements was linked to regions of unstable oxide (either nodule-like, grain boundary penetration, ordifferential grain-to-grain growth) and hypothesized to cause breakaway corrosion.The examination of stable oxide layers was then used as a baseline for comparison to cases ofunstable oxide growth in Zr and Zr alloys. One of the primary modes of examination of stable oxide layersformed on Zr alloys was microbeam synchrotron X-ray radiation diffraction and fluorescence, performedat the Advanced Photon Source (APS) at Argonne National Laboratory. This synchrotron X-ray source wasused to perform -X-ray diffraction (XRD), XRF, and 3D Laue spectroscopy. The XRD technique wasused to determine the oxide layer phase content, strain, and grain size as a function of corrosion temperatureand oxide thickness. The XRF technique was used to perform Fe X-ray absorption near-edge spectroscopyiv(XANES) to determine the oxidation state of Fe in the metal as a function of distance from the metal-oxideinterface for various corrosion temperatures. The 3D Laue spectroscopy technique was used to determineplastic deformation and elastic strain in the metal as a function of distance from the metal-oxide interface,corrosion temperature, and oxide thickness for crystal bar Zr and Zircaloy-4.Additionally, Zircaloy-4 samples were corroded in autoclave at 360C for up to 2804 days in andwere periodically weighed to determine oxide thickness. These samples had different coupon thicknessesthat altered the surface-to-volume ratio and led to a higher concentration of hydrogen for a given amountof oxide layer growth. The concentration of hydrogen was measured in archived samples to determine theeffect of hydrogen concentration on corrosion rate. It was observed that the corrosion rate of Zircaloy-4increased with increasing hydrogen concentration above the terminal solid solubility (TSS) of the material(and thus the precipitation of hydrides). More hydrogen caused earlier kinetic transition and areas ofadvanced oxide growth were associated with the locations of hydrides in the metal. It was hypothesizedthat the hydrides hardened the metal ahead of the interface and that the metal was then less able toaccommodate oxide growth stresses leading to earlier kinetic transition and mechanical cracking of theoxide.Finally, eleven Zircaloy-4 samples exposed to various temperatures (272-355C) and neutron fluxlevels (0-11.48 x 1013 n/cm2/s, E > 1 MeV) were examined using XRD and XRF to determine the effectof irradiation on oxide grain size, phase content, and the oxidation of Fe at the APS. With increasing neutronfluence, the grain size of the oxide increased, leading to less tetragonal phase in the oxide away from themetal-oxide interface. At the metal-oxide interface, higher amounts of tetragonal phase were observed withincreasing neutron fluence. This could be caused by the redistribution of Fe from second phase particles(SPPs) into the matrix or due to the hardening of the Zr matrix caused by the exposure to neutrons.The cases of unstable oxide growth examined here were linked to both the distribution and presenceof alloying elements in Zr and Zr alloys and to the level of stress in the oxide. These two phenomena appearto be the primary causes leading to regions of advanced oxide growth and careful consideration should begiven to them when designing and using future Zr alloys in advanced nuclear reactor concepts.

Download or read book Oxidation of Zirconium and Zirconium Alloys written by and published by . This book was released on 1959 with total page 48 pages. Available in PDF, EPUB and Kindle. Book excerpt: The oxidation rate was found to be relatively insensitive to various types of surface preparations in the temperature range 400 to 700 deg C. No dependence of reaction rate on oxygen pressure was observed. The cubic rate law also was obeyed by foil specimens at 700 deg C; however, the rate constants were slightly larger than values obtained from parallelepiped samples.

Download or read book Zirconium in the Nuclear Industry written by Gerry D. Moan and published by ASTM International. This book was released on 2002 with total page 891 pages. Available in PDF, EPUB and Kindle. Book excerpt: Annotation The 41 papers of this proceedings volume were first presented at the 13th symposium on Zirconium in the Nuclear Industry held in Annecy, France in June of 2001. Many of the papers are devoted to material related issues, corrosion and hydriding behavior, in-reactor studies, and the behavior and properties of Zr alloys used in storing spent fuel. Some papers report on studies of second phase particles, irradiation creep and growth, and material performance during loss of coolant and reactivity initiated accidents. Annotation copyrighted by Book News, Inc., Portland, OR.

Download or read book Understanding Corrosion and Hydrogen Pickup of Zirconium Fuel Cladding Alloys written by Jing Hu and published by . This book was released on 2018 with total page 34 pages. Available in PDF, EPUB and Kindle. Book excerpt: We used a range of advanced microscopy techniques to study the microstructure, nanoscale chemistry, and porosity in zirconium alloys at different stages of oxidation. Samples from both autoclave and in-reactor conditions were available, including ZIRLOTM, Zr-1.0Nb, and Zr-2.5Nb samples with different heat treatments. Scanning transmission electron microscopy (STEM), transmission Kikuchi diffraction (TKD), and automated crystal orientation mapping with TEM were used to study the grain structure and phase distribution. Significant differences in grain morphology were observed between samples oxidized in the autoclave and in-reactor, with shorter, less well-aligned monoclinic grains and more tetragonal grains in the neutron-irradiated samples. A combination of energy-dispersive X-ray mapping in STEM and atom probe tomography analysis of second-phase particles (SPPs) can reveal the main and minor element distributions respectively. Neutron irradiation seems to have little effect on promoting fast oxidation or dissolution of ?-niobium precipitates but encourages the dissolution of iron from Laves-phase precipitates. An electron energy-loss spectroscopy (EELS) analysis of the oxidation state of niobium in ?-niobium SPPs in the oxide revealed the fully oxidized Nb5+ state in SPPs deep into the oxide but Nb2+ in crystalline SPPs near the metal-oxide interface. EELS analysis and automated crystal orientation mapping with TEM revealed Widmanstatten-type suboxide layers in some samples with the hexagonal ZrO structure predicted by ab initio modeling. The combined thickness of the ZrO suboxide and oxygen-saturated layers at the metal-oxide interface correlated well to the instantaneous oxidation rate, suggesting that this oxygen-rich zone is part of the protective oxide that is rate limiting in the transport processes involved in oxidation. Porosity in the oxide had a major influence on the overall rate of oxidation, and there was more porosity in the rapidly oxidizing annealed Zr-1.0Nb alloy than in either the recrystallized alloy or the similar alloy exposed to neutron irradiation.

Download or read book Oxidation and the Testing of Turbine Oils written by Cyril A. Migdal and published by ASTM International. This book was released on 2008 with total page 929 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents papers from a December 2005 symposium held in Norfolk, Virginia, and sponsored by ASTM Committee D2 on Petroleum Products and Lubricants and its Subcommittees D02.09 on Oxidation and D02.C0 on Turbine Oils. Contributors include equipment manufacturers, end users, lubricant producers, lubricant additive suppliers, test equipment manufacturers, and standard test method developers. They share information on industry trends, evolving technologies, and changing equipment designs and operating conditions, with a focus on how these factors impact oxidation. Some topics covered include turbine oil performance limits, a new form of the rotating pressure vessel oxidation test, and degradation mechanisms leading to sludge and varnish in modern turbine oil formulations. B&w photos are included. There is no subject index. Migdal is affiliated with Chemtura Corporation.

Download or read book Zirconium in the Nuclear Industry written by George P. Sabol and published by ASTM International. This book was released on 2000 with total page 953 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plasma Electrolytic Oxidation PEO Coatings written by Marta Mohedano and published by MDPI. This book was released on 2021-06-02 with total page 172 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma electrolytic oxidation (PEO), also known as micro-arc oxidation (MAO), functionalizes surfaces, improving the mechanical, thermal, and corrosion performance of metallic substrates, along with other tailored properties (e.g., biocompatibility, catalysis, antibacterial response, self-lubrication, etc.). The extensive field of applications of this technique ranges from structural components, in particular, in the transport sector, to more advanced fields, such as bioengineering. The present Special Issue covers the latest advances in PEO‐coated light alloys for structural (Al, Mg) and biomedical applications (Ti, Mg), with 10 research papers and 1 review from leading research groups around the world.

Download or read book Effect of Texture and Microstructure of Zircnoium sic Alloys on Their Oxidation and Oxide Texture written by Jianlong Lin and published by . This book was released on 2005 with total page 302 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Anodic Oxidation of Some Dilute Binary Zirconium Alloys written by George Baker Adams and published by . This book was released on 1957 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Zirconium in the Nuclear Industry written by and published by . This book was released on 1996 with total page 930 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Role of the Oxidation Rate on the Hydriding of Zirconium Alloys in Gas Atmospheres Containing Hydrogen written by D. W. Shannon and published by . This book was released on 1963 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book High Temperature Oxidation and Corrosion of Metals written by David John Young and published by Elsevier. This book was released on 2008-10-03 with total page 593 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book is concerned with understanding the fundamental mechanisms of high temperature alloy oxidation. It uses this understanding to develop methods of predicting oxidation rates and the way they change with temperature, gas chemistry and alloy composition. The focus is on designing (or selecting) alloy compositions which provide optimal resistance to attack by corrosive gases. . Emphasises quantitative calculations for predicting reaction rates and the effects of temperature, oxidant activities and alloy compositions. . Uses phase diagrams and diffusion paths to analyse and interpret scale structures and internal precipitation distributions . Provides a detailed examination of corrosion in industrial gases (water vapour effects, carburisation and metal dusting, sulphidation) . Text is well supported by numerous micrographs, phase diagrams and tabulations of relevant thermodynamic and kinetic data . Combines physical chemistry and materials science methodologies.

Download or read book Zirconium in the Nuclear Industry Tenth International Symposium written by A. M. Garde and published by ASTM International. This book was released on 1994 with total page 805 pages. Available in PDF, EPUB and Kindle. Book excerpt: