Author: David Leslie DouglassPublisher:
ISBN:
Category : Zirconium
Languages : en
Pages : 32
Book Description
Corrosion Mechanism of Zirconium and Its Alloys
Author: David Leslie DouglassPublisher:
ISBN:
Category : Zirconium
Languages : en
Pages : 32
Book Description
Corrosion Mechanism of Zirconium and Its Alloys--Diffusion of Oxygen in Zirconium Dioxide
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The diffusion rate of O in anion-deficient zirconia, ZrO/sub 1.994/, was determined by the interface migration of stoichiometric oxide and is represented by the equation D = 0.055 exp ( --33,400 surface proces 3100/RT). A comparison was made with other processes that occur in the metal and the oxide. Excellent agreement was noted between activation energies of O diffusion in ZrO/sub 1.944/ and those for parabolic or cubic oxidation in both air and water. It appears that O diffusion in the oxide is rate-controlling during oxidation of the metal. The corrosion and oxidation behavior of Zr and some alloys are discussed in terms of the oxide defect structure and the electric conductivity behavior in the oxide. A speculative mechanism for corrosion transition to linear rates was suggested on the basis of preferential oxidation of a grain boundary metallic phase. The nature of the phase and of its formation and elimination are discussed. (auth).
The Diffusion of Oxygen in Zirconium and Its Relation to Oxidation and Corrosion
Author: J. Paul PemslerPublisher:
ISBN:
Category : Metals
Languages : en
Pages : 54
Book Description
Oxidation of Zirconium and Zirconium Alloys
Author: Publisher:
ISBN:
Category : Oxidation
Languages : en
Pages : 48
Book Description
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.
Understanding of Corrosion Mechanisms of Zirconium Alloys After Irradiation
Author: Marc TupinPublisher:
ISBN:
Category : Corrosion
Languages : en
Pages : 41
Book Description
The irradiation damage in the fuel cladding material is mainly caused by the neutron flux resulting from the fission reactions occurring in the fuel. From an experimental point of view, the neutrons have the disadvantage to activate materials by neutron capture rendering them difficult to handle. To avoid these constraints inherent in the handling of radioactive material, the radiation effects on the corrosion resistance of zirconium alloys can be studied by irradiating the materials with ions. A new experimental approach using ion irradiation was performed in the Microscopy and Irradiation Damage Studies Laboratory of the CEA in Saclay, with the aim to study more specifically the influence of the irradiation damages in the oxide on the corrosion rate of the zirconium alloys. This study was, moreover, focused on a particular distribution of defects in the oxide layer, basically, localised close to the metal/oxide interface. From the results of the irradiation of the metal/oxide interface, it was clearly shown that, whatever the incident ion, the irradiation of the internal interface results in a significant increase of the oxygen diffusion flux ratios between the most irradiated Zircaloy-4 and the unirradiated one, whereas that of the oxide formed on M5TM induces a big decrease of the oxygen diffusion flux in the film. These effects are less marked with helium ions compared to protons (M5TM is a trademark of AREVA NP registered in the United States and in other countries). Finally, the oxide irradiation impact on the oxygen diffusion through the layer could explain the corrosion acceleration factor observed on Zy4 during the first cycles of irradiation, but cannot alone explain observed corrosion accelerations under high burn-up conditions. The discussion on the oxide irradiation effects puts forward the probable role of the residual charge left by ion implantation.
On the Initial Corrosion Mechanism of Zirconium Alloy
Author: U. DöblerPublisher:
ISBN:
Category : Corrosion
Languages : en
Pages : 19
Book Description
The initial stages of zirconium oxide formation on Zircaloy after water (H2O) and oxygen (O2) exposures have been investigated in situ using photoelectron spectroscopy and X-ray-absorption spectroscopy. The reactivity of the zirconium alloy with O2 at room temperature is about 1000 times higher than for H2O. Up to 100 L (1 L = 1 Langmuir unit = 1 • 10-6 mbar • s) H2O exposure, the reactivity of the zirconium alloy at 450°C is comparable to the room temperature reaction. At higher H2O exposure, a sharp increase in the reaction rate for the high-temperature oxidation is observed. From the energy position of the Zr 3d photo emission line and their oxygen-induced chemical shifts, one can directly follow the formation of the oxide films. Two different substoichiometric oxides were found during reaction with water. Suboxide (1) is located at the zirconium/zirconium-oxide interface. Subsequently, a Suboxide (2) is concluded from the chemical shift of the zirconium photoelectrons. After an oxide thickness of 2 nm, the stoichiometric ZrO2 phase is not yet developed.
Zirconium in the Nuclear Industry
Author: George P. SabolPublisher: ASTM International
ISBN: 0803124996
Category : Microstructure
Languages : en
Pages : 953
Book Description
Corrosion of Zirconium and Zirconium Alloys
Author: Boris Grigorevich ParfenovPublisher:
ISBN:
Category : Zirconium
Languages : en
Pages : 200
Book Description
The Metallurgy of Zirconium
Author: David Leslie DouglassPublisher:
ISBN:
Category : Science
Languages : en
Pages : 496
Book Description
Author: