Miriam Galbiati, Adam Stoot, Peter Bøggild, Luca Camilli
Polytechnic University of Milan, 20133 Milan, Italy.
DTU Nanotech, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
Being impermeable to liquids and gases, graphene, a two-dimensional material made entirely of carbon atoms arranged in a hexagonal lattice, has previously been investigated as a coating to protect metals from oxidation and corrosion. However, due to its nobility and high electrical conductivity, a graphene coating can form a galvanic cell with the metal to be protected, eventually enhancing the oxidation and corrosion processes.
Hexagonal boron nitride (BN) has been suggested as an alternative to graphene for coatings of metals. Indeed, graphene and BN have the same hexagonal structure and comparable impermeability to gases [Bunch JS, Nano Lett 2008], but since BN is an electrical insulator, it does not cause galvanic corrosion. Here we present a comparative study showing that BN coatings are superior to graphene coatings for long-term protection of copper substrates against oxidation. The evolution of Raman signals for copper oxides in bare, graphene- and BN-coated copper samples during two different series were measured. In the first series, samples were kept at 50°C for 60 hours, while in the second series the samples were heated from room temperature up to 400°C within 45 minutes. The results indicate that while both graphene and BN offer good short term protection, BN-coatings offer superior protection in the long term.
 Bunch JS, Verbridge SS, Alden JS, van der Zande AM, Parpia JM, Craighead HG, McEuen PL, Impermeable atomic membranes from graphene sheets. Nano Lett. 2008 Aug;8(8):2458-62.
Miriam Galbiati is currently a student in Nuclear Engineering (MSc) at the Polytechnic University of Milan where she also received her B.S. degree in Materials Engineering and Nanotechnology. In order to complete her Master's Thesis project she spent 7 months as a guest student in the Nanotech Department at Technical University of Denmark studying the possibility of using graphene and boron nitride as coatings against oxidation and corrosion of copper.
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