EMIRUM 2014 Advanced AlO3 coatings under extreme conditions Francisco Garcia Ferre1, Alexander Mairov2, Cedric Baumier3, Odile Kaitasov3, Dario Gastaldi4, Pasquale Vena4, Patrick Trocellier5, Yves Serruys5, Lucile Beck5, Kumar Sridharan2, Marco G. Beghi6 and Fabio Di Fonzo1 1 Center for Nanoscience and Technology, Istituto Italiano di Tecnologia,Via G. Pascoli 70/3, 20133 Milano (MI), Italia 2 Department of Engineering Physics, University of Wisconsin-Madison, Madison, WI 53706, USA 3 CNRS/IN2P3/CSNSM/SEMIRAMIS, Université Paris Sud, Bat 108, 91400 Orsay, France 4 Dipartimento di Chimica, Materiali e Ingegneria Chimica, Politecnico di Milano, Piazza Leonardo Da Vinci 2, 20133 Milano (MI), Itaia 5 Service de Recherches de Metallurgie Physique, Laboratoire JANNUS, CEA, DEN, F-91191, Gif-SurYvette, France 2 Dipartimento di Energia, Politecnico di Milano, Via Ponzio 34/3, 20133 Milano (MI), Italia [email protected] In future generation nuclear systems cooled by Heavy Liquid Metals (HLMs), such as lead or leadbismth eutectic (LBE), fuel cladding will be exposed to an extremely harsh environment, in which radiation dose will approach 150 displacements per atom (dpa) at a temperature of up to 800°C. In addition, corrosion of structural steels by HLMs stands as a major bottleneck. In this work, we propose the use of a nanocrystalline Al 2O3/amorphous Al2O3 composite coating as a corrosion barrier for high temperature operation of steels in HLMs . The barrier layer is grown by Pulsed Laser Deposition (PLD) at room temperature. The mechanical properties of the coating are assessed with high accuracy and precision trough a novel opto-mechanical method , based on the combination of ellipsometry, Brillouin spectroscopy and nanoindentation. The adhesive strength is evaluated by nanoscratch tests. The coating attains an unusual combination of compactness, strong interfacial bonding, moderate stiffness (E=195±9 GPa and ν=0,29±0,02) and significant hardness (H=10±1 GPa), resulting in superior plastic behavior and a relatively high ratio of hardness to elastic modulus (H/E=0,049). These features are correlated to the nanostructure of the coating, which comprises a regular dispersion of ultra-fine crystalline Al2O3 nano-domains (2-5 nm) in a dense and amorphous alumina matrix. Corrosion aspects are examined by short- and mid-term exposure of samples to stagnant HLMs at 600°C. Post-test analysis reveal no signs of corrosion, confirming the strong chemical inertia of the coatings . The performance of the alloy substrate-ceramic coating system under high dose radiation damage is studied by irradiation with heavy ions up to 20, 40 and 150 dpa at 600°C. Structural features and mechanical properties are evaluated respectively by in-situ and ex-situ TEM analysis and nanoindentation. References  F. García Ferré, M. Ormellese, F. Di Fonzo, M.G. Beghi. Corros. Sci. 77 (2013), 375.  F. García Ferré et al. Acta. Mater. 61 (2013), 2662.