Regular Article

Development of MgO_x–TiO_x coatings for modulation of Mg corrosion resistance

¹ Department of Mechanical Engineering, DICIS, Universidad de Guanajuato, carretera Salamanca-Valle de Santiago km. 3.5 + 1.8, 36885 Salamanca, Gto., Mexico
² Department of Agricultural Mechanical Engineering, DICIVA, Universidad de Guanajuato, ex Hacienda el Copal carretera Irapuato-Silao km. 9, 36500 Irapuato, Gto., Mexico
³ CICATA-Legaria, Instituto Politécnico Nacional, Calzada Legaria 694, Col. Irrigación, 11500 Ciudad de México, Mexico
⁴ Applied Physics Department, CINVESTAV-IPN, Antigua Carretera a Progreso km. 6, Cordemex, Loma Bonita Xcumpich, 97310 Mérida, Yuc., Mexico

^* email: noe.hernandez@ugto.mx

Received: 11 May 2017
Accepted: 19 October 2017

Abstract

The development and testing of protective coatings against corrosion for magnesium is reported. The coatings were based on the MgO_x–TiO_x composite and for their fabrication the reactive RF-sputtering technique in the co-deposition mode was employed. MgO_x–TiO_x coatings with chemical composition ranging from pure Mg oxides to pure Ti oxides, including its mixture, were obtained through the variation of the rate of the sputtering powers applied to the Mg and Ti targets. Characterization (XRD and XPS) showed changes in the crystalline structure according to the rate of the sputtering powers and confirmed the presence of MgO₂, MgO, Ti₂O₃ and TiO₂ in different proportions. Electrochemical polarization measurements (Tafel) made by employing the Hank's solution showed that both V_corr and I_corr depend on the chemical composition of the coatings, having better corrosion resistance when the content of Ti oxides is higher. Results showed that corrosion resistance of Mg could be modulated by changing the chemical composition of the MgO_x–TiO_x coatings.