Plasma Electrolytic Oxidation (PEO) Process—Processing, Properties, and Applications

Abstract

Plasma electrolytic oxidation (PEO) is a novel surface treatment process to produce thick, dense metal oxide coatings, especially on light metals, primarily to improve their wear and corrosion resistance. The coating manufactured from the PEO process is relatively superior to normal anodic oxidation. It is widely employed in the fields of mechanical, petrochemical, and biomedical industries, to name a few. Several investigations have been carried out to study the coating performance developed through the PEO process in the past. This review attempts to summarize and explain some of the fundamental aspects of the PEO process, mechanism of coating formation, the processing conditions that impact the process, the main characteristics of the process, the microstructures evolved in the coating, the mechanical and tribological properties of the coating, and the influence of environmental conditions on the coating process. Recently, the PEO process has also been employed to produce nanocomposite coatings by incorporating nanoparticles in the electrolyte. This review also narrates some of the recent developments in the field of nanocomposite coatings with examples and their applications. Additionally, some of the applications of the PEO coatings have been demonstrated. Moreover, the significance of the PEO process, its current trends, and its scope of future work are highlighted.

Advanced Surface Modification for 3D-Printed Titanium Alloy Implant Interface Functionalization

“…MAO is the method of using arc discharge to enhance and activate the reaction on the anode on the basis of ordinary anodic oxidation, to form a high-quality reinforced ceramic film on the metals ( Li et al, 2004 ). In the electrolytic oxidation process, various parameters affect the quality of the coating, such as voltage, type of current, electrolyte composition, substrate material, and process duration ( Sikdar et al, 2021 ). Similar to anodizing, MAO also forms porous micro-nano structure on the implant surface.…”

Surface Modification of 6xxx Series Aluminum Alloys

“…Basically, such coatings isolate structural members from the environments, improving the material's corrosion resistance. Some of these coatings are developed following hard anodizing, cladding, priming, cold spraying, plasma electrolytic oxidation (PEO), and similar methods [23][24][25][26]. When they are put into service, some of the Al alloys would be experiencing mechanical and tribological conditions.…”

Effect of Molybdate on Corrosion Performance of Oxide Coating Produced on 7075 Al Alloy Using PEO

“…As seen in Figure 2, the Ra increases with incrementing concentration from 0 to 5 g L −1 , which is also in agreement with the FESEM images. The higher final voltage results in a coarse microstructure [27,28]. Furthermore, the high tendency formation of crater features and granules of oxide compounds increases the surface roughness.…”