Role of Iron for Hydrogen Absorption Mechanism in Zirconium Alloys PDF Download
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Author: K. Kakiuchi Publisher: ISBN: Category : Corrosion Languages : en Pages : 18
Book Description
The latest PIE results of Zry-2 and HiFi alloy (0.4 %Fe-Zry2) showed that iron addition reduces the hydrogen pick-up ratio. In order to clarify this lower hydrogen absorption mechanism, three types of experiments were carried out for both alloys: (1) Measurements of the hydrogen pick-up ratio in the pre-transition region using an autoclave. (2) CPD (Contact Potential Difference) and FBP (Flat-band Potential) measurements of oxide film using a High Temperature Kelvin system and Photocurrent system. (3) Investigation of hydrogen absorption properties by Sieverts system and corrosion properties by autoclave for intermetallic compounds simulating SPP's Fe/Cr and Fe/Ni ratio in Zry-2 and HiFi.
Author: K. Kakiuchi Publisher: ISBN: Category : Corrosion Languages : en Pages : 18
Book Description
The latest PIE results of Zry-2 and HiFi alloy (0.4 %Fe-Zry2) showed that iron addition reduces the hydrogen pick-up ratio. In order to clarify this lower hydrogen absorption mechanism, three types of experiments were carried out for both alloys: (1) Measurements of the hydrogen pick-up ratio in the pre-transition region using an autoclave. (2) CPD (Contact Potential Difference) and FBP (Flat-band Potential) measurements of oxide film using a High Temperature Kelvin system and Photocurrent system. (3) Investigation of hydrogen absorption properties by Sieverts system and corrosion properties by autoclave for intermetallic compounds simulating SPP's Fe/Cr and Fe/Ni ratio in Zry-2 and HiFi.
Author: Cyril A. Migdal Publisher: ASTM International ISBN: 0803134932 Category : Antioxidants Languages : en Pages : 929
Book Description
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.
Author: Michael Smialowski Publisher: Elsevier ISBN: 1483213714 Category : Science Languages : en Pages : 469
Book Description
Hydrogen in Steel: Effect of Hydrogen on Iron and Steel During Production, Fabrication, and Use focuses on the effect of hydrogen on iron and steel during production, fabrication, and use. Topics covered range from the solubility of hydrogen in iron and ferrous alloys to the diffusion and permeation of hydrogen through iron and steel. Electrochemical problems related to the ability of iron to absorb hydrogen from aqueous solutions are also considered. Comprised of 19 chapters, this book begins with a detailed treatment of the nature and properties of metal-hydrogen systems, paying particular attention to the behavior of hydrogen in the bulk of the metal phase and the mechanism of reactions between metals and hydrogen or hydrogen-producing compounds. The reader is then introduced to the solubility of hydrogen in iron and ferrous alloys as well as the nature of the final product of the hydrogen-iron interaction. Subsequent chapters deal with dimensional changes and stresses produced in steel by cathodically evolved hydrogen; the effects of hydrogen on the physical, mechanical, and chemical properties of iron and steel; influence of welding on hydrogen; and sulfide corrosion cracking of steel. The effects of pickling on steel are also examined, along with the blistering and embrittlement caused by hydrogen on the base metal during electroplating. This book will be of value to students and practitioners in the field of physical chemistry.
Author: Adrien Couet Publisher: ISBN: Category : Languages : en Pages :
Book Description
Although the optimization of zirconium based alloys has led to significant improvements in hydrogen pickup and corrosion resistance, the mechanisms by which such alloy improvements occur are still not well understood. In an effort to understand such mechanisms, a systematic study of the alloy effect on hydrogen pickup is conducted, using advanced characterization techniques to rationalize precise measurements of hydrogen pickup. The hydrogen pick-up fraction is accurately measured for a specially designed set of commercial and model alloys to investigate the effects of alloying elements, microstructure and corrosion kinetics on hydrogen uptake. Two different techniques to measure hydrogen concentrations were used: a destructive technique, Vacuum Hot Extraction, and a non-destructive one, Cold Neutron Prompt Gamma Activation Analysis. The results indicate that hydrogen pickup varies not only from alloy to alloy but also during the corrosion process for a given alloy. For instance Zircaloy type alloys show high hydrogen pickup fraction and sub-parabolic oxidation kinetics whereas ZrNb alloys show lower hydrogen pickup fraction and close to parabolic oxidation kinetics. Hypothesis is made that hydrogen pickup result from the need to balance charge during the corrosion reaction, such that the pickup of hydrogen is directly related to (and indivisible of) the corrosion mechanism and decreases when the rate of electron transport or oxide electronic conductivity through the protective oxide increases. According to this hypothesis, alloying elements (either in solid solution or in precipitates) embedded in the oxide as well as space charge variations in the oxide would impact the hydrogen pick-up fraction by modifying electron transport, which drives oxidation and hydriding kinetics. Dedicated experiments and modelling were performed to assess and validate these hypotheses.In-situ electrochemical impedance spectroscopy (EIS) experiments were performed on Zircaloy-4 tubes to directly measure the evolution of oxide electronic conductivity as function of exposure time. The results show that oxide electronic conductivty decreases as function of exposure time and that its variations are directly correlated to the instantaneous hydrogen pickup fraction variations. The electron transport through the oxide layer is thus altered as the oxide grows, reasons for which are yet to be exactly determined. Preliminary results also show that oxide electronic conductivty of ZrNb alloys would be much higher compared with Zircaloy-4. Thus, it is confirmed that oxide electronic conductivity is a key parameter in the hydrogen and oxidation mechanism.Because the mechanism whereby alloying elements are incorporated into the oxide layer is critical to changing [sigma]_(e^-)^ox, the evolution of the oxidation state of two common alloying elements, Fe and Nb, when incorporated into the growing oxide layers is investigated using X-Ray Absorption Near-Edge Spectroscopy (XANES) using micro-beam synchrotron radiation on cross sectional oxide samples. The results show that the oxidation of both Fe and Nb is delayed in the oxide layer compared to that of Zr, and that this oxidation delay is related to the variations of the instantaneous hydrogen pick-up fraction with exposure time. The evolution of Nb oxidation as function of oxide depth is also compatible with space charge compensation in the oxide and with an increase in oxide electronic conductivity of ZrNb alloys compared to Zircaloys.Finally, various successively complex models from the well-known Wagner oxidation theory to the more complex effect of space charge on oxidation kinetics have been developed. The general purpose of the modeling effort is to provide a rationale for the sub-parabolic oxidation kinetics and demonstrate the correlation with hydrogen pickup fraction. It is directly demonstrated that parabolic oxidation kinetics is associated with high oxide electronic conductivity and low space charges in the oxide whereas sub-parabolic oxidation kinetics is associated with lower oxide electronic conductivity and higher space charge in the oxide.All these observations helped us to propose a general corrosion mechanism of zirconium alloys involving both oxidation and hydrogen pickup mechanism to better understand and predict the effect of alloying additions on the behavior of zirconium alloys.
Author: K. Kakiuchi
Author: K. Kakiuchi
Author: Cyril A. Migdal
Author: K. Une
Author: E. Hillner
Author: Michael Smialowski
Author: 
Author: Adrien Couet
Author: Warren E. Berry
Author: Myra S. Feldman
Author: