Surfaces and Interfaces II: Materials-related Electrochemistry, Chemical Reactivity and Applications

Abstract

Introduction to fundamentals of (electro)chemical surface processes on conducting materials: reactivity, degradation, functionalizing and deposition. Relevant oxidation/corrosion mechanisms are presented always in relation with suitable characterizations (focus: electrochemical & surface analytical methods) and data analysis. Characterization of (thin film) metal oxides are also addressed.

Objective

The students should learn and understand the fundamental mechanisms responsible for the most important corrosion phenomena affecting "classical" industrial relevant metals/alloys and they should know the limitation in the use of these "standard" materials in aggressive environments. They should be able to explain in detail the degradation mechanisms of Stainless Steels and Aluminium alloys always presented as reference materials during the lecture. Moreover and more importantly, they should then be able to transfer this acquired knowledge about corrosion mechanisms and surface functionalyzing directly in the developments phase of very different new materials/coatings. This know-how is essential in order to minimize the corrosive failure risks and increase the sustainability of new industrial products. Finally and as most important asset of the lecture, they should know how to approach a corrosion problem/failure and be able to propose the right characterization techniques/methodology to investigate each specific corrosion problems. For this purpose, the extended lecture now sets a stronger emphasis on electrochemical processes description and understanding with special topics dedicated to experimental data analysis (the NOVA/INTELLO software will be made available to the registered students) and also on thin surface oxide characterization. These defective amorphous oxides with different properties than the bulk crystalline ones plays a key role in surface reactivity but also on surface protection.

Content

The most important types of corrosion mechanisms will be presented and discussed during the different lectures. The semester will start with some short basics about thermodynamics and reaction kinetics. Afterwards and for each specific corrosion phenomenon, the most relevant experimental characterization method will always be introduced directly after the explanations about the corrosion mechanism. This combination allows the student to couple theoretical physico-chemical concepts with practical characterization methodologies used in corrosion research. It also indicates the most relevant methodologies to answer each of the stages of a degradation process. Following topics will be presented (mechanism/method used): - Thermodynamics related to corrosion processes prediction - Corrosion reaction kinetics / DC electrochemical methods - Passivation and passive film properties / XPS (X-Ray Photoelectron Spectroscopy) and EQCM (Electrochemical Quartz Crystal Microgravimetry) - Uniform corrosion/Electrochemical Impedance Spectroscopy (EIS) with the example of Magnesium biocorrosion - Galvanic corrosion/AFM-SKPFM (Atomic Force Microscopy based Scanning Kelvin Probe Force Microscopy) - Localized corrosion (pitting)/ Microcapillary cell technique - Photoelectrochemistry and Crevice corrosion with description of specific electrochemical setups and medical implant problems - Intergranular corrosion and mathematical modelling concepts / Microtomography - Stress corrosion cracking (SCC) / corrosion-fatigue - Selected examples of functional anodic oxide growth and more "exotic" corrosion mechanisms (Si, Ag, Ta, a.s.o), corrosion protection and surface functionalizing will be presented at the end if times permit The special topics lecture will also contain two focusses: One part directly linked to the core lecture with a stronger focus on electrochemical data treatment/analysis session a. With classical exercises always related to methods presented during the core lecture b. The lecturer will then also introduce various software's for thermodynamic calculation and for electrochemical measurements. The software will previously be made available to the students and they will receive small assignments to solve and present/discuss during the lecture c. "Advanced" topic: Biocorrosion and the metal(oxide)-biology interface topic will be introduced as an important field where interaction/corrosion mechanisms are still poorly understood Alternately, a detailed description of thin oxide (very relevant to passivation and biocorrosion mechanisms) and their reactivity/characterization will be presented. The lecture will start with the description of various oxide growth methods: a. General short introduction about oxide deposition methods b. Anodizing/electrodeposited oxides c. Thermal oxidation (oxidation and reduction kinetics, e.g. Cu) And continue with the various characterization of thin amorphous/defective oxides by: d. Ellipsomety, advanced XRD analysis (pair distribution) e. Stress analysis (Digital image correlation, stress curvature) f. Rutherford Backscattering / ERDA g. Raman/FTIR h. HAXPES – chemical state analysis i. Synchrotron (EXAFS, XANES) and neutron methods j. Photoluminescence Each methodology supported by presentation of research and applications examples (mainly Al, Ti, Si, Ta, Hf, etc).

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