Incorporation of multi-walled carbon nanotubes into the oxide layer on a 7075 Al alloy coated by plasma electrolytic oxidation: Coating structure and corrosion properties

Plasma electrolytic oxidation (PEO) is an electrochemical-based surface modification technique that produces oxide layers on valve metals. The PEO process is performed in an electrolyte solution, which offers the possibility of particles’ incorporation into the growing oxide layer. In this study, we employed a PEO technique on a commercial Al alloy in an aqueous suspension of carbon nanotubes (CNTs) to fabricate CNT-incorporated oxide layer. The voltage–time response was recorded during the process. The surface of the resulting oxide layer was characterized by means of a scanning electron microscope (SEM), an energy-dispersive X-ray spectrometer (EDS), and X-ray diffraction (XRD). It was found from the SEM observation that the CNTs were successfully incorporated into the oxide layer. The PEO with the addition of CNTs led to a delay in time to breakdown (50[Formula: see text][Formula: see text][Formula: see text]s) and a decrease in breakdown voltage (442[Formula: see text][Formula: see text][Formula: see text]V) in the voltage–time curve. The microstructural feature was clearly distinguishable between the oxide layers produced with and without CNTs: a pancake-like structure for PEO without CNTs, and a doughnut-like structure for PEO with CNTs. However, neither the results of the structure analysis nor the elemental analysis provides a clear indication of carbon, even though the presence of CNTs in the oxide layer is evident, suggesting that further optimization of CNT concentration is required.

Download Full-text

Incorporation of Carbon Nanotubes Into Oxide Layer on 7075 Al Alloy by Plasma Electrolytic Oxidation

Journal of The Electrochemical Society ◽

10.1149/1.3617754 ◽

2011 ◽

Vol 158 (10) ◽

pp. C325 ◽

Cited By ~ 22

Author(s):

Kang Min Lee ◽

Jong Oh Jo ◽

Eung Seok Lee ◽

Bongyoung Yoo ◽

Dong Hyuk Shin

Keyword(s):

Carbon Nanotubes ◽

Oxide Layer ◽

Plasma Electrolytic Oxidation ◽

Al Alloy ◽

7075 Al Alloy ◽

Electrolytic Oxidation ◽

Plasma Electrolytic

Download Full-text

Oxide Layer Modification of Mg-Al Alloy Coated by Plasma Electrolytic Oxidation Using Zirconia Particles

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.463-464.406 ◽

2012 ◽

Vol 463-464 ◽

pp. 406-409 ◽

Cited By ~ 1

Author(s):

D.Y. Choi ◽

J. Hwang ◽

K.M. Lee ◽

K.R. Shin ◽

Y.G. Ko ◽

...

Keyword(s):

Oxide Layer ◽

Plasma Electrolytic Oxidation ◽

Al Alloy ◽

Zirconia Powder ◽

Corrosion Properties ◽

Electrolytic Oxidation ◽

Valve Metal ◽

Structure Observation ◽

Plasma Electrolytic ◽

Peo Coatings

The paper reported the effect of zirconia incorporation on the oxide layer modification of the valve metal such as magnesium coated by plasma electrolytic oxidation (PEO). To incorporate zirconia particles into the oxide layer, PEO coatings were carried out under AC condition in electrolytes containing zirconia powder. After PEO coatings, structure observation revealed that a number of zirconia particles were distributed uniformly throughout the oxide layer while the size and distribution of pores remained unchanged as compared to the results coated by PEO without zirconia. It was found that fine zirconia particles incorporated into the oxide layers played an important role in enhancing the anti-corrosion properties of bare metal.

Download Full-text