Enhanced Corrosion Resistance of SiC_p/ 2009 Al by Cerium and Lanthanum Conversion Treatment

Abstract:

The present study investigates the effect of lanthanide chlorides conversion coatings on the corrosion response of the 2009 Al alloy and SiC_p reinforced 2009 Al MMCs. Electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization studies showed that the localized corrosion resistance increased after treatments with solutions having various combinations of CeCl₃.7H₂O and LaCl₃.7H₂O, with maximum increase noticed for 5000ppm CeCl₃.7H₂O. It was found that the protection degree effect obtained under similar coating conditions for 25 vol.% SiC_p/2009 Al was relatively higher than 15vol.% SiC_p/ 2009 Al MMC, but both of them were less than that of the unreinforced alloy. Scanning electron microscopy (SEM) accompanied with energy dispersive spectroscopy (EDS) analysis revealed the deposition of Ce and/ or La oxides/ hydroxides on cathodic intermetallics/ SiC_p and the existence of crevices at the SiC_p/ matrix interfaces. X-ray photoelectron spectroscopy (XPS) results indicated that Ce was incorporated as Ce³⁺ and Ce⁴⁺ species in the coatings.

• Periodical: Key Engineering Materials (Volume 778)
• Pages: 251-255
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.778.251
• Online since: September 2018
• Authors: Irfan Aziz, Qi Zhang
• Keywords: EIS, Potentiodynamic Polarization, SiC_p/2009 Al Composite, Thermal Conversion Coatings

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