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Master Thesis on Electrochemical characterisation of Cu-Zn alloy and prediction of their atmospheric corrosion behaviour in presence of nitrogen compounds
The proposed master thesis will focus on developing an in-situ methodology to study the atmospheric corrosion behaviour of brass. A new electrochemical microcell should therefore be designed. This new setup will provide a deeper understanding of processes leading to alloy failure.
Copper alloys such as brass (Cu-Zn) are extensively used in a wide range of industrials applications due to their versatile physical properties and good corrosion resistance. The presence of ions, such as Cl-, SO42- and NH4+, in the environment however drastically affects the corrosion behaviour of copper alloys. Nitrogen and sulphur can bond with copper promoting or inhibiting further degradation depending on the compound structure. Despite having been widely studied for the last decades, the interactions between copper and nitrogen compounds at the solid/liquid interface are still not fully understood from a fundamental mechanistic point of view.
In this project, the atmospheric corrosion behaviour of a Cu70-Zn30 alloy will be investigated in chloride containing solutions in presence of different N-containing compounds. A combined electrochemical and surface analytical approach will be used to establish the reaction mechanisms in the different solutions as well as the alloy surface composition after exposure. Preliminary study has shown that the corrosion mechanisms of the CuZn alloy in presence of the following compounds: Tris(hydroxymethyl)aminomethane (Tris), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (Hepes) and Benzotriazole (BTA) highly depend on the type of chemical bonding and complexation of the copper ions by the different N-containing compounds.
Copper alloys such as brass (Cu-Zn) are extensively used in a wide range of industrials applications due to their versatile physical properties and good corrosion resistance. The presence of ions, such as Cl-, SO42- and NH4+, in the environment however drastically affects the corrosion behaviour of copper alloys. Nitrogen and sulphur can bond with copper promoting or inhibiting further degradation depending on the compound structure. Despite having been widely studied for the last decades, the interactions between copper and nitrogen compounds at the solid/liquid interface are still not fully understood from a fundamental mechanistic point of view. In this project, the atmospheric corrosion behaviour of a Cu70-Zn30 alloy will be investigated in chloride containing solutions in presence of different N-containing compounds. A combined electrochemical and surface analytical approach will be used to establish the reaction mechanisms in the different solutions as well as the alloy surface composition after exposure. Preliminary study has shown that the corrosion mechanisms of the CuZn alloy in presence of the following compounds: Tris(hydroxymethyl)aminomethane (Tris), 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (Hepes) and Benzotriazole (BTA) highly depend on the type of chemical bonding and complexation of the copper ions by the different N-containing compounds.
The master thesis project will be conducted at the Laboratory of Joining Technologies and Corrosion (Empa). The investigated material is a commercially available brass, Cu70-Zn30. Its corrosion behaviour will be discussed in relation to the reactivity of pure copper and zinc.
1) Identify the effect of pH on the corrosion mechanisms in selected solutions in presence of N-containing compounds (electrochemical methods, alloy surface composition, speciation)
2) Determine the effect of stress relaxation heat treatment on the corrosion behaviour of the alloy.
3) Development of an in-situ methodology to study the atmospheric corrosion behaviour of Cu alloys. Compare macroscale to microscale mechanisms and surface composition
4) Tomography of deeply attacked samples. Can we determine the propagation mechanisms and prevent such degradation?
At the end of the project, the candidate will have acquired some expertise in the fields of corrosion science, electrochemistry and surface preparation. This project will allow the candidate to strengthen his/her skills in electrochemical characterisation (cyclic voltammetry, EIS) at the macro- and microscale. Additionally, the candidate will be given the opportunity to learn other characterization techniques, such as scanning electron microscopy (SEM), environmental scanning Kelvin probe force microscopy (AFM/SKPFM) and Auger electron spectroscopy (AES) and their associated sample preparation.
The master thesis project will be conducted at the Laboratory of Joining Technologies and Corrosion (Empa). The investigated material is a commercially available brass, Cu70-Zn30. Its corrosion behaviour will be discussed in relation to the reactivity of pure copper and zinc. 1) Identify the effect of pH on the corrosion mechanisms in selected solutions in presence of N-containing compounds (electrochemical methods, alloy surface composition, speciation) 2) Determine the effect of stress relaxation heat treatment on the corrosion behaviour of the alloy. 3) Development of an in-situ methodology to study the atmospheric corrosion behaviour of Cu alloys. Compare macroscale to microscale mechanisms and surface composition 4) Tomography of deeply attacked samples. Can we determine the propagation mechanisms and prevent such degradation? At the end of the project, the candidate will have acquired some expertise in the fields of corrosion science, electrochemistry and surface preparation. This project will allow the candidate to strengthen his/her skills in electrochemical characterisation (cyclic voltammetry, EIS) at the macro- and microscale. Additionally, the candidate will be given the opportunity to learn other characterization techniques, such as scanning electron microscopy (SEM), environmental scanning Kelvin probe force microscopy (AFM/SKPFM) and Auger electron spectroscopy (AES) and their associated sample preparation.
If you are interested or want to learn more, please contact Dr. Noémie Ott (noemie.ott@empa.ch), daily supervisor or Dr. Patrik Schmutz (patrik.schmutz@empa.ch), group leader Functional Surfaces, Empa Dübendorf
If you are interested or want to learn more, please contact Dr. Noémie Ott (noemie.ott@empa.ch), daily supervisor or Dr. Patrik Schmutz (patrik.schmutz@empa.ch), group leader Functional Surfaces, Empa Dübendorf