Eventos Anais de eventos
COBEF 2017
Congresso Brasileiro de Engenharia de Fabricação
DEVELOPMENT OF CERIUM BASED CONVERSION COATINGS FOR CORROSION PROTECTION OF AZ91D MAGNESIUM ALLOY
Submission Author:
Eloana Patrícia Ribeiro , SP
Presenter: Eloana Patrícia Ribeiro
doi://10.26678/ABCM.COBEF2017.COF2017-0117
Abstract
The aim of the present work was to develop cerium conversion coatings on the surface of the AZ91D magnesium alloy. The converted layers were produced upon immersion in cerium nitrate solution at room temperature for different times (10 s, 20 s, 30 s, 60 s and 120 s). Surface morphology was examined using scanning electron microscopy (SEM).The surface chemical composition of the cerium-based films was determined by x-ray photoelectron spectroscopy (XPS) analyses. The effect of the treatment time on the corrosion resistance of the coated AZ91D alloy was assessed by electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization using a 3.5 wt.% NaCl solution at room temperature as the electrolyte. The results revealed that the cerium films presented several microcracks and exfoliated regions. Nodular agglomerates were mainly formed on the specimens treated for long times (60 s and 120 s).The cerium content was not directly related to treatment time. The best corrosion resistance was observed for the specimens treated for 20 s.
Keywords
AZ91D alloy, cerium conversion coating, XPS
