RT journal article
T1 Influence of Aerospace Standard Surface Pretreatment on the Intermetallic Phases and CeCC of 2024-T3 Al-Cu Alloy
A1 Alba Galvín, Juan Jesús
A1 González Rovira, Leandro
A1 Bethencourt Núñez, Manuel
A1 Botana Pedemonte, Francisco Javier
A1 Sánchez Amaya, José María
A2 Ciencia de los Materiales e Ingeniería Metalúrgica y Química Inorgánica
K1 aluminium
K1 alloy phases
K1 corrosion
K1 surface pretreatments
K1 CeCC
AB A standard three-step surface pretreatment employed in the aerospace sector for Al alloyshave been investigated prior to the generation of cerium conversion coatings (CeCC) on aluminiumcopperalloy 2024. Two pretreatments were analysed, one without final acid etching (Pretreatment1) and another with this step (Pretreatment 2). Both pretreatments affect the alloy intermetallicphases, playing a key role in the development of the CeCC, and also in the susceptibility to localisedcorrosion in NaCl medium. Scanning electron microscopy coupled with energy-dispersive X-rayanalysis (SEM-EDX) revealed that after Pretreatment 2, Al(Cu,Mg) phases were partially or totallyremoved through dealloying with their subsequent copper enrichment. Conversely, none of theseintermetallic phases were affected when the final acid step was not employed (Pretreatment 1).Meanwhile, Al-Cu-Fe-Mn-(Si) phases, the other major Al–Cu alloys intermetallics, suffers minorchanges through the whole pretreatments chain. The protective efficiency of CeCC was evaluatedusing electrochemical techniques based on linear polarisation (LP) and electrochemical impedancespectroscopy (EIS). Samples with CeCC deposited after the Pretreatment 1 gave higher polarisationresistance and impedance module than CeCC deposited after Pretreatment 2. SEM-EDX and X-rayphotoelectron spectroscopy analysis (XPS) indicate that the main factors explaining the corrosionresistance of the coatings is the existence of Al(Cu,Mg) intermetallics in the surface of the alloy,which promote the deposition of a cerium-based coating rich in Ce4+ compounds. These Al(Cu,Mg)intermetallics were kept in the 2024 alloy when acid etching was not employed (Pretreatment 1).
PB MDPI
SN 2075-4701
YR 2019
FD 2019-03
LK http://hdl.handle.net/10498/21218
UL http://hdl.handle.net/10498/21218
LA eng
DS Repositorio Institucional de la Universidad de Cádiz
RD 21-sep-2026