ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Synergistic inhibition and assessment of Y₂O₃ corrosion impact on AZ92 magnesium alloy by stir casting process in chloride media by response surface methodology

Lamiaa Z. Mohamed, Shimaa El-Hadad, M. E. Moussa, and Ghalia A. Gaber

Mining, Petroleum, and Metallurgical Engineering Department, Faculty of Engineering, Cairo University, Giza, Egypt

E-mail: lamiaa.zaky@cu.edu.eg

Received: 26 June 2025  Accepted: 30 July 2025

Abstract:

This study explores the corrosion behavior of cast AZ92 magnesium alloy modified with 0–3.0 wt% Y₂O₃ produced by a stir casting process in 3.5% NaCl solution, both with and without inhibitors 0.01 mg/L AgNO₃, 0.01 mg/L Ce(NO₃)₃, and 0.01 mg/L Mo(NO₃)₂. A novel approach combining gravimetric analysis, electrochemical techniques (EIS, polarization), and response surface methodology (RSM) was used to optimize corrosion resistance (CRST). Results reveal that 2.5 wt% Y₂O₃ provides the lowest corrosion rate (0.80 mm/y) when Ce(NO₃)₃ present, which is attributed to refinement of β-phase. SEM confirmed compact Mg(OH)₂-rich surface films, while RSM identified Y₂O₃ content as the most influential factor (F = 531.18, p = 0.000), followed by time and media. Electrochemical tests showed enhanced polarization resistance (up to 1901.7 Ω) and stable passive films at 1.5–2.5 wt% Y₂O₃. However, higher Y₂O₃ levels reduced protection due to film instability and agglomeration. The synergistic role of Y₂O₃ and Ce(NO₃)₃ was most effective, with optimal conditions predicted by RSM. These findings provide a promising corrosion control strategy using rare earth oxides and multivariate optimization.

Keywords: AZ92 magnesium alloy; Yttrium oxide; Corrosion inhibitors; Electrochemical analysis; Chloride environment; Response surface methodology

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-025-04285-0

Chemical Papers 79 (11) 7745–7768 (2025)