Corrosion resistance of ZrN x O y thin films obtained by rf reactive magnetron sputtering E. Ariza a,b , L.A. Rocha a,b, * , F. Vaz c , L. Cunha d , S.C. Ferreira a , P. Carvalho c , L. Rebouta c , E. Alves e , Ph. Goudeau f , J.P. Rivie `re f a Research Centre on Interfaces and Surface Performance, Azure ´m, 4800-058 Guimara ˜es, Portugal b Universidade do Minho, Dept. Eng. Meca ˆnica, Azure ´m, 4800-058 Guimara ˜ es, Portugal c Universidade do Minho, Dept. Fı ´sica, Azure ´m, 4800-058 Guimara ˜es, Portugal d Universidade do Minho, Dept. Fı ´sica, Campus de Gualtar, 4710-057 Braga, Portugal e ITN, Departamento de Fı ´sica, E.N.10, 2685 Sacave ´m, Portugal f Laboratoire de Me ´tallurgie Physique, Universite ´ de Poitiers, 86960 Futuroscope, France Available online 18 October 2004 Abstract The main aim of this work is the investigation of the corrosion resistance of single layered zirconium oxynitride, ZrN x O y , thin films in artificial sweat solution at ambient temperature. The films were produced by rf reactive magnetron sputtering, using a pure Zr target at a constant temperature of 300 8C. Two different sets of samples were produced. In the first set of films, the substrate bias voltage was the main variable, whereas in the second set, the flow rate of reactive gases (oxygen/nitrogen ratio) was varied. The control of the amount of oxygen allowed the film properties to be tailored from those of covalent zirconium nitride to those of the correspondent ionic oxide. The corrosion behaviour was evaluated by potentiodynamic polarization and Electrochemical Impedance Spectroscopy (EIS) tests. The analysis of EIS data provided detailed information of the corrosion processes occurring at the surface of the system throughout the immersion time. The modifications of the coating microstructure and/or chemical composition induced by the variation of the deposition parameters were also evaluated and correlated with the corrosion mechanisms occurring in each system. D 2004 Elsevier B.V. All rights reserved. Keywords: Corrosion; Magnetron sputtering; Thin films 1. Introduction In the last few years, an emergent field of research is gaining more and more importance—the so-called deco- rative thin films. These colored films possess a high potential for being applied in high-quality consumer products, such as eyeglass frames, wristwatch casings and wristbands. In fact, while enhancing the appearance of the pieces by lending attractive colorations to their surfaces, these films are supposed to provide simultaneously scratch- resistance and improved corrosion resistance. Up to now, decorative films are mostly based on elemental materials and also binary nitrides (TiN, golden yellow; ZrN, greenish yellow; HfN, pale greenish yellow [1]) or titanium carbonitrides [1,2]. The color tones attainable are, however, largely restricted to these golden yellows, various shades of grey and black [2,3], although some attempts have been made in order to obtain other colors, based on borides [3]. Recently, a new class of materials is gaining importance for these decorative applications, the so-called metal oxynitrides, MeN x O y (Me=early transition metal) [4–6]. This importance results from the fact that the presence of oxygen allows the tailoring of film properties between those of bpureQ covalent metal nitride and those of the correspondent largely ionic oxides. Recent publications suggest that the performance of these oxynitrides depends not only on the deposition 0040-6090/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.tsf.2004.08.091 * Corresponding author. Universidade do Minho, Dept. Eng. Meca ˆ- nica, Azure ´m, 4800-058 Guimara ˜es, Portugal. Tel.: +351 253 510 231; fax: +351 253 516 007. E-mail address: lrocha@dem.uminho.pt (L.A. Rocha). Thin Solid Films 469–470 (2004) 274 – 281 www.elsevier.com/locate/tsf