Download or read book Microstructure of Oxide Layers Formed During Autoclave Testing of Zirconium Alloys written by H-O Andrén and published by . This book was released on 1994 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The microstructure of oxide layers formed in steam in a 400°C, 10.3-MPa autoclave on different zirconium alloys was studied by transmission electron microscopy. Pre-and post-transition oxide layers on Zircaloy-4 with different heat treatments, and post-transition oxide layers on Zr-0.5Sn-0.53Nb were compared. Special attention was paid to the oxide-metal interface. In Zircaloy-4 with short annealing times and high post-transition corrosion rates, the interface had a disordered structure, and pores were found in the oxide very close to the interface. In Zircaloy-4 with low uniform corrosion rates, the interface consisted of highly ordered, columnar grains. The interface in Zr-0.5Sn-0.53Nb had a different appearance, with an intermediate phase of equiaxed grains between the columnar oxide and the metal. The hydrogen absorption of the zirconium alloys during oxidation was measured by the melt extraction technique on samples oxidized for 63, 147, and 343 days. The Zr-0.5Sn0.53Nb alloy had considerably lower hydrogen absorption than Zircaloy-4.
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:
Download or read book Microstructure of Oxide Films Formed During the Waterside Corrosion of the Zircaloy 4 Cladding in Lithiated Environment written by D. Pêcheur and published by . This book was released on 1996 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Zircaloy-4 cladding materials have been oxidized in a lithiated environment in autoclave and in out-of-pile loop tests. In such oxidation tests, a strong enhancement of the oxidation rate can occur depending on the water chemistry conditions and on the oxidation time. In this work, in order to improve our understanding of the detrimental effect of lithium on the corrosion behavior of the Zircaloy-4 cladding, the microstructure of oxide films has been characterized by TEM. Simultaneously, the lithium profiles and concentrations in the oxide layers have been determined using the SIMS technique, special attention being paid to the metal-oxide interface.
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 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 D. G. Franklin and published by ASTM International. This book was released on 1984 with total page 866 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 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 Microstructural Characterization of Oxides Formed on Model Zr Alloys Using Synchrotron Radiation written by A. T. Motta and published by . This book was released on 2008 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: To understand how alloy chemistry and microstructure impact corrosion performance, oxide layers formed at different stages of corrosion on various model zirconium alloys (Zr-xFe-yCr, Zr-xCu-yMo, for various x, y) and control materials (pure Zr, Zircaloy-4) were examined to determine their structure and the connection of such structure to corrosion kinetics and oxide stability. Microbeam synchrotron radiation diffraction and fluorescence of oxide cross sections were used to determine the oxide phases present, grain size, and orientation relationships as a function of distance from the oxide-metal interface. The results show a wide variation of corrosion behavior among the alloys, in terms of the pretransition corrosion kinetics and in terms of the oxide susceptibility to breakaway corrosion. The alloys that exhibited protective behavior at 500°C also were protective during 360°C corrosion testing. The Zr-0.4Fe-0.2Cr model ternary alloy showed protective behavior and stable oxide growth throughout the test. The results of the examination of the oxide layers with microbeam X-ray diffraction show clear differences in the structure of protective and nonprotective oxides both at the oxide-metal interface and in the bulk of the oxide layer. The nonprotective oxide interfaces show a smooth transition from metal to oxide with metal diffraction peaks disappearing as the monoclinic oxide peaks appear. In contrast, the protective oxides showed a complex structure near the oxide-metal interface, showing peaks from Zr3O suboxide and a highly oriented tetragonal oxide phase with specific orientation relationships with the monoclinic oxide and the base metal. The same interfacial structures are observed through their diffraction signals in protective oxide layers formed during both 360°C and 500°C corrosion testing. These diffraction peaks showed much higher intensities in the samples from 500°C testing. The results for the various model alloys are discussed to help elucidate the role of individual alloying elements in oxide formation and the influence of oxide microstructure on the corrosion mechanism.
Download or read book Study of the Initial Stage and Anisotropic Growth of Oxide Layers Formed on Zircaloy 4 written by B. X. Zhou and published by . This book was released on 2011 with total page 29 pages. Available in PDF, EPUB and Kindle. Book excerpt: An in situ investigation of the epitaxial oxide layer formed on a thin specimen heated in a transmission electron microscope was carried out. Some dot-like grains about 10 nm in size were formed on the surface of a relatively thin area. The dot-like grains are monoclinic zirconium oxide and have an orientation relationship of (001)m//(01 ̄11)?-Zr, (001)m//(11 ̄01)?-Zr, with the ?-Zr matrix. Some long strip-like grains, probably a new kind of zirconium suboxide, were formed on the surface of a relatively thick area. The strip-like grains have a bcc structure with a lattice parameter a=0.66 nm and have an orientation relationship of (110)bcc//(10110)?-Zr, [1110]bcc//[0001]?-Zr with the ?-Zr matrix. The relationship between the thickness of oxide layers and the grain orientations of the ?-Zr matrix was studied with coarse-grained Zircaloy-4 specimens through autoclave corrosion tests at 500 and 400°C in superheated steam, and at 360°C in both lithiated and deionized water for long time exposure. The results show that the anisotropic growth of oxide layers on the grain surface with different orientations is considerable. However, the relationship between the thickness of oxide layers and the grain orientations of the ?-Zr matrix varies with corrosion temperature and water chemistry. The largest variation of oxide thickness developed during corrosion tests at 500°C. The thickest oxide layers were formed on those grains whose surface orientations were distributed around the planes from (011 ̄0) to (1 ̄21 ̄0). The thicker oxide layers on these grains were further developed into nodular corrosion. When the specimens were corroded at 360°C in lithiated water, the thickest oxide layers formed on those grains, whose surface orientations tilted from 15 to 30° away from the (0001) plane. When the specimens were corroded at 400°C in superheated steam and at 360°C in deionized water, the difference between the thickness of oxide layers on different grain surfaces was less prominent.
Download or read book Microstructure of Oxides on Zircaloy 4 1 0Nb Zircaloy 4 and Zircaloy 2 Formed in 10 3 MPa Steam at 673 K written by H. Anada and published by . This book was released on 1996 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: The microstructure of ZrO2 formed on sheet materials of Zircaloy-2 (Zr2), Zircaloy-4 (Zr4), and an alloy of 1.0% Nb added to Zircaloy-4 (1Nb-Zr4) was analyzed using HRTEM (high-resolution transmission electron microscopy). The relationship between the corrosion behavior of the alloys and the microstructure is discussed. Stress-relieved sheet specimens of the three alloys were prepared and corrosion tested under static conditions in steam at 673 K and 10.3 MPa for a total of 220 days. The order of corrosion resistance in 673-K steam was Zr2, 1Nb-Zr4, and Zr4. Several transitions were observed in the corrosion kinetic curve of 1Nb-Zr4 and Zr2. However, only the first transition was observed in the curve of Zr4. Oxide structure in the pre-transition region on Zr4 was analyzed to be in the following order from the outside surface: columnar m-ZrO2, t-ZrO2 layer, substoichiometric Zr oxide layer, and ?-Zr matrix. The t-ZrO2 layer was approximately 50 to 80 nm thick, and the substoichiometric Zr oxide layer was approximately 100 to 200 nm. These layers were absent in the microstructure of the oxide in the post-transition region. The substoichiometric Zr oxide layer consisted of m-ZrO2 grains that were less than 10 nm in diameter and some as yet unidentified grains that had lattice parameters similar to distorted and significantly oriented ?-Zr. However, the t-ZrO2 layered structure and the substoichiometric Zr oxide layer structure were observed in the post-transition oxides on Zr2 and 1Nb-Zr4. It was also observed that transformation of columnar grains to fine equiaxed grains had occurred near the lateral cracks and the incorporated intermetallic precipitates in post-transition oxides. It is implied from these results that the t-ZrO2 layer and the substoichiometric Zr oxide layer structures play an important role as a barrier layer in controlling the occurrence of kinetic transitions.
Download or read book Microscopy of Oxidation written by Gordon Tatlock and published by . This book was released on 2000 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition Elements Advances in Research and Application 2012 Edition written by and published by ScholarlyEditions. This book was released on 2012-12-26 with total page 2682 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition Elements—Advances in Research and Application: 2012 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Transition Elements. The editors have built Transition Elements—Advances in Research and Application: 2012 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Transition Elements in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Transition Elements—Advances in Research and Application: 2012 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.
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 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 Microscopy of Oxidation written by and published by . This book was released on 2000 with total page 386 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Detailed Analysis of the Microstructure of the Metal Oxide Interface Region in Zircaloy 2 After Autoclave Corrosion Testing written by Pia Tejland and published by . This book was released on 2011 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
