The effect of PEO parameters on the properties of biodegradable Mg alloys: a review

Abstract

This paper comprehensively reviews recent research carried out in the field of preparation of bioactive coatings on magnesium (Mg)–aluminum (Al)–zinc (Zn) alloys by using the plasma electrolytic oxidation (PEO) method and investigation of factors affecting it. Magnesium–aluminum–zinc alloys (AZ grades) have been developed for use as biodegradation materials because the addition of aluminum and zinc as alloying elements can ameliorate their mechanical properties and increase corrosion resistance over those of pure magnesium alone without decrement in biocompatibility. Among the common methods for improvement of biodegradation, corrosion resistance and biocompatibility of magnesium alloys, surface modification techniques have been more effective. PEO is a relatively novel surface modification technique that provides excellent wear- and corrosion-resistant coatings on lightweight metals, in particular on magnesium and its alloys. The processing parameters of PEO, such as pulse frequencies, applied voltages, oxidation time, electrolyte concentrations and substrate chemical composition, are some of the major factors that determine the quality of the coatings in terms of corrosion resistance and bioactivity in body fluid solutions. Considering the fact that comprehensive review articles on the effect of PEO parameters on the properties of magnesium alloys have not been published in recent years, the aim of the present text is to provide an understanding of all aspects of these process parameters.

Oxyhydroxide-Coated PEO–Treated Mg Alloy for Enhanced Corrosion Resistance and Bone Regeneration

“…Moreover, high temperatures (over 2000 °C) on the substrate surface can melt the coating and result in strong binding forces between the coating and substrate [ 17 , 18 ]. Numerous studies have treated Mg with PEO and investigated its orthopedic applications [ 19 , 20 ]. Rendenbach et al modified WE43 Mg alloy with PEO treatment and found that the PEO-treated Mg alloy showed enhanced corrosion resistance and osteointegration upon implantation in Gottingen miniature pigs [ 21 ].…”

Unveiling the Effect of Particle Incorporation in PEO Coatings on the Corrosion and Wear Performance of Magnesium Implants

“…As mentioned earlier, by subjecting the magnesium surface to controlled plasma discharges, a ceramic oxide layer is formed, imparting superior hardness and wear resistance. Moreover, PEO-coated magnesium implants demonstrate remarkable resilience against abrasive wear [170]. The hardened ceramic layer serves as a robust barrier, minimizing direct contact between the magnesium substrate and abrasive surfaces.…”

Biological Performance of Duplex PEO + CNT/PCL Coating on AZ31B Mg Alloy for Orthopedic and Dental Applications

“…Different coatings on Mg alloys, including metal oxide [ 15 ], polymer coatings [ 16 ], inorganic nonmetallic coatings [ 18 ], and composite coatings [ 14 ], have been investigated to increase their corrosion resistance, biocompatibility, and osteointegration [ 19 , 20 , 21 ]. Among various methods, plasma electrolytic oxidation (PEO) is considered an ideal and simple technique for the surface modification of Mg alloys due to its high adhesion strength to the substrate and the adjustable composition [ 22 , 23 ]. PEO coatings are typically produced in modified alkaline electrolytes, such as phosphate, silicate, or sodium hydroxide solutions [ 24 ].…”