Korean Institute of Surface Engineering

pISSN : 1225-8024 | eISSN : 3399-8403


공학

한국표면공학회지 (55권3호 143-155)

Corrosion behaviors of plasma electrolytic oxidation (PEO) treated highsilicon aluminum alloys


Deok-Yong Parka,*, Chong-Hyun Changb, Yong-Jun Oha, Nosang V. Myungc, Bongyoung Yood


aDepartment of Advanced Materials Engineering, Hanbat National University, Daejeon, 34158, Republic of Korea bCalifornia NanoSystems Institute, University of California, Los Angeles, CA 90025, USA cDepartment of Chemical and Biomolecular Engineering, University of Notre Dame, Notre Dame, IN 46656, USA dDepartment of Materials Engineering, Hanyang University, Ansan, 15588, Republic of Korea

DOI : 10.5695/JSSE.2022.55.3.143

Abstract

Ceramic oxide layers successfully were formed on the surface of cast Al alloys with high Si contents using plasma electrolytic oxidation (PEO) process in electrolytes containing Na2SiO3, NaOH, and additives. The microstructure of the oxide layers was systematically analyzed using scanning electron microscopy (SEM), cross-sectional transmission electron microscopy (TEM), X-ray diffraction patterns (XRD), and energy X-ray dispersive spectroscopy (EDS). XRD analysis indicated that the PEO untreated high-silicon Al alloys (i.e., 17.1 and 11.7 wt.% Si) consist of Al, Si and Al2Cu phases whereas Al2Cu phase selectively disappeared after PEO treatment. PEO process yielded an amorphous oxide layer with few second phases including γ-Al2O3 and Fe-rich phases. The corrosion behaviors of high-silicon Al alloys treated by PEO process were investigated using electrochemical impedance spectroscopy (EIS) and other electrochemical techniques (i.e., open circuit potential and polarization curve). Electroanalytical studies indicated that high-silicon Al alloys treated by PEO process have greater corrosion resistance than high-silicon alloys untreated by PEO process.

Keywords

Electrochemical process; plasma electrolytic oxidation (PEO); corrosion behaviors; high-silicon aluminum alloys.