Proceedings of the 3rd International Symposium on High Temperature Corrosion and Protection of Materials
Actes du 3ème Colloque International sur la Corrosion et la Protection des Matériaux à Haute Température

J. Phys. IV France 03 (1993) C9-477-C9-483
DOI: 10.1051/jp4:1993951

Initial stages of cobalt oxidation by FTIR spectroscopy

M. Lenglet¹, J. Lopitaux¹, L. Terrier¹, P. Chartier², J.F. Koenig², E Nkeng² and G. Poillerat<sup>2

1</sup>  Laboratoire de Physicochimie des Matériaux, Université de Rouen, B.P. 08, 76131 Mont Saint Aignan Cedex, France
²  Laboratoire d'Electrochimie et de Chimie Physique du corps solide, URA 405, ULP, 4 rue Blaise Pascal, 67000 Strasbourg, France

Abstract
The behaviour of specular reflectance of cobalt oxides on metal has been studied theoretically (CoO/Co system) and experimentally (Co₃O₄/Co system; the thin films are obtained by chemical spray pyrolysis) in the infrared region. CoO may be identified by a LO mode at 585 cm^-1 and by a TO mode at 345 cm^-1. Co₃O₄ is characterized by five bands respectively at 690 (LO), 660 (TO), 605 (LO), 560 (TO) and 390 cm^-1. These experimental results allow the characterization of CoO and Co₃O₄ grown on metal during the initial stages of thermal oxidation (400-750 °C). For film thicknesses in the range 10-1000 nm, the amounts of CoO and Co₃O₄ in the duplex structure layers may be estimated by FTIR reflectance spectroscopy. FTIR and XRD studies reveal a cyclic behaviour in the growth of the Co₃O₄/CoO/Co system.

© EDP Sciences 1993