ABSTRACT
Magnesium alloys are considered biodegradable materials for implants in recent years due to their excellent biocompatibility, biodegradability and reasonable mechanical properties. However, their lower corrosion resistance and quick degradation in the physiological environment are the main difficulties for their wide application. Different methods, including surface treatment, mechanical processing and alloying have been utilized to lower the corrosion rate of magnesium alloys. A legitimate design of an implant material is intended to give the essential functionality, durability and biological response. The biological response relies on the surface topography, surface chemistry, surface charge, surface roughness and surface energy, whereas bulk properties of materials decide the functionality and durability of materials. It is accepted that the implant surface morphology assumes a significant role in the biocompatibility of implants in vivo; it influences the cell functions and behavior. Surface modifications to change surface attributes have been demonstrated powerful in improving corrosion resistance and biocompatibility of the materials. With an ultimate objective to improve the cell–implant interaction, various surface modifications methods were inspected in recent years to stimulate osseointegration and enhance surface properties of magnesium alloys. Contrasted with other surface modification methods, micro-arc oxidation (MAO) can give great adhesion, hard, wear-resistant and corrosion-resistant coating on magnesium and its alloys. MAO is an electrochemical treatment strategy to make protective metal oxide coatings on a substrate, such as Ti, Al and Mg. MAO is fundamentally a single-step method to make protective coatings on light metal and its alloys for dental and orthopedic applications. With variations in the process variables of MAO, anticipated coating properties can be achieved, such as processing time, frequency, applied voltage, electrolyte composition and duty cycle. This article mostly surveys the impact of key process parameters of MAO on the surface properties of magnesium alloys. In addition, the effects of different process variables like the type of electrolyte, power supply parameters and oxidation time on corrosion performance are discussed in this chapter.
