Download or read book Physical and Chemical Characterization of Oxide Layers Formed on Fe Cr Al Alloys in Liquid Pb45Bi55 and Its Alternatives at High Temperatures written by Miroslav Popovic and published by . This book was released on 2017 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lead-bismuth eutectic (LBE, Pb45Bi55) is a promising candidate alloy for use as a fluid in heat storage and transport applications in nuclear and solar power generating systems, due to its superior thermal, chemical, physical and neutron-moderating properties. In order to further improve the thermal efficiency in these systems, it is a goal to push the operating (upper) temperature up to 800 oC or more. However, a major drawback in using liquid LBE at high temperatures is the increasing solubility of many chemical elements from solids in LBE (particularly nickel from austenitic materials). This can be mitigated by adding an appropriate amount of oxygen into liquid LBE and keeping control of the oxygen concentration to enable formation of protective oxide layer or layers on or near the structural material surface, whereby the oxidation of the elements depends on temperature, oxygen concentration and chemical potential of oxidation. Addition of aluminum to the iron-based ferritic materials has been found to be beneficial in preventing dissolution and excessive oxidation, by forming an Al-oxide layer that provides an effective diffusion barrier for metal ions and protects the material. In this work, the structure of the oxide phases formed on candidate materials after exposure to oxygenated LBE at temperatures up to 800 C has been analyzed and characterized by various spectroscopic and microscopic methods. Three Fe-Cr-Al ferritic alloys, containing various percentages of Al and Cr, have been exposed to LBE in an in-house designed experimental setup in controlled oxygen atmosphere, in various test duration. The main goal was to determine the influence of four factors on the formation of oxide layers: Al content in Fe-Cr-Al alloys, temperature, oxygen content in LBE, and duration of exposure. The structural analysis of the layers has been performed by transmission electron microscopy, energy-dispersive X-ray spectroscopy, Raman spectrometry and X-ray photoelectron spectroscopy. It has been found that the oxygen content in LBE around 1×10-6 wt% is optimal for the formation of stable, continual and well-adhered oxide layers. Higher Al content in steels stimulates formation of mostly Al2O3, while lower Al content leads to the enrichment in Fe- and Cr-oxides. At higher oxygen content (5×10-6 wt% O) and lower Al content, at 800 0C, formed oxide scale is a complex structure of more than one layer. Lowering of the oxygen concentration to 1×10-6 wt% in LBE at same temperature leads to the reduction in diversity of oxides (further domination of Al-oxide), while the concentration of 1×10-7 wt% O was found to be too low for compact and well-defined scales formation. The same effect of enrichment in Al2O3 in oxide scales is obtained by lowering the temperature. Oxide scales degradation is another topic that has been dealt with in the study. At high temperatures and higher oxygen concentration in LBE, the diffusion of oxygen through the oxide layers into the bulk increases and may lead to the internal oxidation of Al. This can generate strain in the oxide and in near-oxide bulk due to the mismatch between the crystal structures of oxides and of the bulk, leading subsequently to the oxide layers breaking and spallation. The other cause of strain can be the mismatch of thermal expansion coefficients of oxides and of the bulk, in cooling at the end of heat transfer systems operation. Strain in the oxide scales might lead to their breaking and failure. According to the results obtained by the X-ray microdiffraction analysis, strain in the lattice mainly comes from plastic deformation, and more dominant mechanism of strain induction is by the internal oxidation. Besides that, the influence of an additional thermal disturbance has been studied by inducing a mid-term thermal cycle in corrosion tests in LBE at various test temperatures. It has been found that thermal cycling leads to the increase in oxide scales failure with the increase in operating temperature and with increasing Al content in samples. The last goal of this work was to investigate if the addition of a third element X (a minor additive) to LBE can improve the protection of structural materials by possible formation of intermetallic layers, besides the oxides, i.e. to design and evaluate optimal Pb-Bi-X ternary alloys as an alternative to LBE. Theoretical considerations indicated Pb-Bi-Sb and Pb-Bi-Ge as the most promising alternatives, while the experimental evaluation gave some evidence of the intermetallic formation only on high-Al tested sample in Pb-Bi-Sb. However, no significant advantage over LBE has been found in behavior of these two ternary alloys towards the Fe-Cr-Al materials.
Download or read book Passivation of Metals and Semiconductors and Properties of Thin Oxide Layers written by Philippe Marcus and published by Elsevier. This book was released on 2006-05-25 with total page 765 pages. Available in PDF, EPUB and Kindle. Book excerpt: Passivation of Metals and Semiconductors, and Properties of Thin Oxide Layers contains a selection of papers presented at PASSIVITY-9, the 9th International Symposium on the Passivation of Metals and Semiconductors and the Properties of Thin Oxide Layers, which was held in Paris, 27 June - 1 July, 2005. One hundred and twelve peer-reviewed manuscripts have been included. The book covers all the fundamental and applied aspects of passivity and provides a relevant and updated view of the advances and new trends in the field. It is structured in ten sections: • Growth, (Nano)structure and Composition of Passive Films • Passivity of Semiconductors • Electronic Properties of Passive Films • Passivity Issues in Biological Systems • Passivity in High-Temperature Water • Mechanical Properties of Passive Films,• Passivity Issues in Stress Corrosion Cracking and Tribocorrosion • Passivity Breakdown and Localized Corrosion • Modeling and Simulation • Surface Modifications and Inhibitors (for Improved Corrosion Resistance and/or Adhesion)
Download or read book Characterization of Zircaloy 4 Oxide Layers by Scanning Electron Microscopy written by Michael Pantano and published by . This book was released on 2012 with total page 36 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Buried Oxide Layers Prepared by the Oxygen Implantation Technique written by Frederick T. Brady and published by . This book was released on 1987 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Characterization of Buried Oxide Layers Formed by Oxygen Implantation written by Frederick T. Brady and published by . This book was released on 1991 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electrical Characterization of Metal oxide silicon Structures with Ultra Thin Oxide Layers written by Per Lundgren and published by . This book was released on 1996 with total page 55 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Naturally Grown Oxide Layers on Copper with and Withot Benzotriazole by Electrochemical and Photoelctrochemical Measurements written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Transition Metal Oxides written by P.A. Cox and published by Oxford University Press. This book was released on 2010-08-19 with total page 295 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transition metal oxides form a series of compounds with a uniquely wide range of electronic properties. The main aim of this book is to describe the varied electronic behaviour shown by transition metal oxides, and to discuss the different types of theoretical models that have been proposed to interpret this behaviour.
Download or read book Optimization and Characterization of Transparent Oxide Layers for CIGS Solar Cells Fabrication written by Qiudi Liu and published by . This book was released on 2007 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, we studied the structural, electrical, and optical properties of three different transparent oxides compounds in their thin film forms. These three compounds were aluminum doped zinc oxide (ZnO:Al), indium tin oxide (ITO) and intrinsic zinc oxide (ZnO). These films are a critical part of Cu(In,Ga)Se2 solar cells, as they play the role of the front contact collecting the photo-generated carriers while letting the photons penetrate into the active semiconductor layers. The films were deposited by radio frequency (r.f.) magnetron sputtering on soda lime glass. We investigated the change of the thin film properties in terms of the main deposition parameters: deposition pressure, substrate temperature, and target r.f. power. Similar trends were found for ZnO:Al and ITO, which were correlated with results from the literature. The optical band gap and the conductivity tend to decrease for increased deposition pressure, while they increase for increased substrate temperature or target power. The crystallinity and the surface roughness tend to increase for an increase of all three parameters, even if some parabolic shapes are obtained for some of the properties. For the ZnO films, the optical band gap and the conductivity do not change with the deposition pressure, substrate temperature or target power, while the crystallinity and the surface roughness tend to increase. These results were correlated with references from other research group
Download or read book Magnesium Alloys and Technologies written by Karl U. Kainer and published by John Wiley & Sons. This book was released on 2006-03-06 with total page 293 pages. Available in PDF, EPUB and Kindle. Book excerpt: The need for light-weight materials, especially in the automobile industry, created renewed interest in innovative applications of magnesium materials. This demand has resulted in increased research and development activity in companies and research institutes in order to achieve an improved property profile and better choice of alloy systems. Here, development trends and application potential in different fields like the automotive industry and communication technology are discussed in an interdisciplinary framework.
Download or read book Characterization of Oxidation Products on a ZrFe2 type Laves Intermetallic Exposed to 200 C Steam written by and published by . This book was released on 2000 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The release of radioactive elements from the stainless steel-15 wt% zirconium (SS-15Zr) metal waste form will be governed by the corrosion behavior of ZrFe2-type intermetallics phases present in the alloy. In this article, oxidation products that formed on a ZrFe2-type intermetallic sample exposed to 200 C steam were characterized by Auger Electron Spectroscopy (AES) and Transmission Electron Microscopy (TEM). The data revealed two oxide layers on the sample surface: an outer crystalline iron-oxide layer and an inner amorphous zirconium-rich layer believed to be zirconium oxide. Thermodynamic considerations indicate that the zirconium-rich layer formed first. The iron-oxide layer appears to have resulted from the diffusion of iron through the zirconium-rich layer to the oxide-vapor interface.
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 Analysis of Oxide Layers on Nitrocarburised Steels written by Timothy Vaughan and published by . This book was released on 2003 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Structure Characterization of Adsorbed Poly ethylene Oxide Layers on Solid Substrate written by Fen Chen (M.S.) and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Characterization of Oxide Films Grown by Flow accelerated Corrosion Using Scanning Electron Microscope SEM and Focused Ion Beam FIB Techniques written by Cale MacLennan and published by . This book was released on 2020 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Flow-Accelerated corrosion (FAC) has remained an issue in steam raising power plants with FAC being the cause of enhanced degradation of plant piping and if the degradation continues it can develop into unexpected pipe wall failure. Therefore understanding the mechanisms of FAC is necessary in order to predict where it will occur and what can be done to mitigate it. To this end a morphology study was conducted on probes corroded by FAC in various conditions. By observing the changes in oxide layer morphology in response to changes in system conditions more information about the mechanisms of FAC can be inferred. The information gained from the morphology study was then used to update the UNB mechanistic model to improve the accuracy of its predictions. After updating the model, it was able to predict FAC rates and oxide thicknesses quite well in both neutral and ammoniated conditions for two different compositions of steel.
Download or read book Atomic Layer Deposition and Characterization of Metal Oxide Thin Films written by Ali Mahmoodinezhad and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Perform Tests and Document Results and Analysis of Oxide Layer Effects and Comparisons written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: During the initial feasibility test using actual used nuclear fuel (UNF) cladding in FY 2012, an incubation period of 30-45 minutes was observed in the initial dry chlorination. The cladding hull used in the test had been previously oxidized in a dry air oxidation pretreatment prior to removal of the fuel. The cause of this incubation period was attributed to the resistance to chlorination of an oxide layer imparted by the dry oxidation pretreatment on the cladding. Subsequently in 2013, researchers at the Korea Atomic Energy Institute (KAERI) reported on their chlorination study [R1] on 9̃-gram samples of unirradiated ZirloTM cladding tubes that had been previously oxidized in air at 500oC for various time periods to impart oxide layers of varying thickness. In early 2014, discussions with Indefinite Delivery, Indefinite Quantity (IDIQ) contracted technical consultants from Westinghouse described their previous development (and patents) [R2] on methods of chemical washing to remove some or all of the hydrous oxide layer imparted on UNF cladding during irradiation in light water reactors (LWRs) . Thus, the Oak Ridge National Laboratory (ORNL) study, described herein, was planned to extend the KAERI study on the effects of anhydrous oxide layers, but on larger 1̃00-gram samples of unirradiated zirconium alloy cladding tubes, and to investigate the effects of various methods of chemical pretreatment prior to chlorination with 100% chlorine on the average reaction rates and Cl2 usage efficiencies.
