Introduction 1. Aqueous Corrosion 2. Environments and Application Examples 3. high-Temperature Corrosion 4. Modeling, Life Prediction, and Computer Applications 5. Corrosion Failures 6. Corrosion Maintenance Through Inspection And Monitoring 7. Acceleration and Amplification of Corrosion Damage 8. Materials Selection 9. Protective Coatings 10. Corrosion Inhibitors 11. Cathodic Protection 12. Anodic Protection

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Handbook of Corrosion Engineering

Microstructural characterizations of magnetron sputtered Ti films on glass substrate

Changes in electrochemical properties of the anodic oxide film formed on titanium during potential sweep

Ti–Al–V powder metallurgy (PM) via the hydrogenation–dehydrogenation (HDH) process

TIIVISTELMÄ FOREWORD ....................................................................................................... 3

An Update of the State-of-the-art Report on the Corrosion of Copper Under Expected Conditions in a Deep Geologic Repository

For the conditions expected in a Canadian nuclear waste vault, the two corrosion processes most likely to lead to the failure of titanium waste containers are crevice corrosion and/or hydrogen induced cracking (HIC). In this report the processes likely to lead to hydrogen absorption by titanium alloys (Grades-2, -12, -16), and hence to render them susceptible to HIC are discussed. The possible paths to container failure via a combination of crevice corrosion, general passive corrosion and HIC are described and a criterion for container failure by HIC is defined. The modelling procedures developed to predict the consequences of hydrogen absorption are described, and the experimental methods used to measure required modelling parameters are discussed and the results summarized. The predictions of these models show that for alloys on which crevice corrosion either does not occur or is limited in extent (Ti-16 and Ti-12), container lifetimes of >10 a are achievable. As a result only those containers assumed to fail prematurely due to the presence of manufacturing defects need be included in assessment calculations.

Hydrogen Absorption and the Lifetime Performance of Titanium Nuclear Waste Containers

Hydrogen-induced cracking of commercial purity titanium

A model was developed to predict the failure of Grade-2 titanium (Ti-2) nuclear waste containers. Two major corrosion modes were included: failure by crevice corrosion (CC) and failure by hydrogen-induced cracking (HIC). A small number of containers were assumed to be defective and to fail within 50 years of emplacement. The model is probabilistic in nature, and each modeling parameter was assigned a range of values, resulting in a distribution of corrosion rates and failure times. The crevice corrosion rate (RCC) was assumed to be dependent only upon properties of the material used and the temperature of the vault. CC was assumed to initiate rapidly on all containers and to propagate indefinitely without repassivation. Failure by HIC was assumed to be inevitable once container temperature (T) fell to ≤ 30°C. Depending upon the rate at which they were expected to cool, temperature-time profiles for individual containers were approximated by two-step or single-step temperature-time functions. Thes...

Modeling the Failure of Nuclear Waste Containers

Stress corrosion cracking (SCC) is a possible failure mode for Cu containers in an underground nuclear waste disposal vault. It is difficult to guarantee that SCC will never initiate on Cu containers based only on the results of relatively short-term experiments. Therefore, the extent of SCC is being predicted based on the argument that the rate of crack propagation will be limited. Several environmental factors will limit the rate of cracking, including: the general absence of aggressive SCC agents in the vault, the limited time of rapid strain of the container shell and the limited supply rate of oxidants (principally dissolved O{sub 2}) to the container surface through the compacted clay-based material in which the containers will be placed. In the first part of this study, the effect of oxidant flux on the crack velocity is being determined. The SCC behavior of two high-copper alloys has been determined in nitrite-containing environments over a range of oxidant fluxes. In NO{sub 2}{sup {minus}} solutions, transgranular SCC is observed. There is evidence for discontinuous crack advance, including crack arrest markings on fracture surfaces and correlated noise events in the electrochemical potential and applied load signals. Crack velocities of 4--8 nm/s are observed inmore » constant extension rate tests in 0.1 mol{center{underscore}dot}dm{sup {minus}3} sodium nitrite (NaNO{sub 2}) with applied current densities of 0.1--1.0 {micro}{center{underscore}dot}cm{sup {minus}2}. The maximum crack length for a Cu container has been estimated based on the observed dependence of the crack velocity on the oxidant flux and the predicted time dependence of the oxidant flux to the containers in a disposal vault.« less

The Stress Corrosion Cracking of Copper Containers for the Disposal of High-Level Nuclear Waste

Approaches to modelling the corrosion of nuclear waste containers are reviewed. The required containment of many thousands of years makes this a daunting task. The process has been simplified for a disposal vault in which redox conditions evolve from initially oxidizing to eventually non-oxidizing. The corrosion behaviour can be divided into two periods: an early hot, oxidizing period when localized corrosion damage is to be expected; and a later cool, non-oxidizing period when localized processes would be stifled, or repassivated, and general corrosion will predominate. At present, deterministic models to predict localized corrosion damage during the early period are unavailable or, at best, preliminary. Generally, the approach to predicting localized penetration of the container has been stochastic in nature and extreme value statistical analyses have been used to predict the expected penetration of carbon steel or copper containers by pitting. Experiments to determine the rate of crevice propagation in titanium are discussed and a model developed to predict failure of titanium waste containers by either crevice corrosion or hydrogen-induced cracking described. General corrosion occurring in the second, less oxidizing, period is more amenable to modelling by deterministic methods. Models based on electrochemical descriptions of the interfacial kinetics are described for carbon steel and copper containers, two materials expected to corrode actively under waste vault conditions. To date, no adequate model exists to predict the slow general corrosion of passivated materials.

B.M. Ikeda

Papers

Hydrogen Absorption and the Lifetime Performance of Titanium Nuclear Waste Containers

Hydrogen-induced cracking of commercial purity titanium

Modeling the Failure of Nuclear Waste Containers

The Stress Corrosion Cracking of Copper Containers for the Disposal of High-Level Nuclear Waste

Modelling Procedures for Predicting the Lifetimes of Nuclear Waste Containers