Micro-Arc Oxidation of Titanium and Its Alloys

Research conducted around improving the longevity of implants primarily focuses on designing metallic materials to minimize infectious and non-infectious causes of implant rejection. Improving implant effectiveness can be achieved through the selection of materials, manufacturing methods, and ultimately, engineering its surface. Micro-arc oxidation/plasma electrolytic oxidation (MAO/PEO), known as one of the electrochemical surface treatment methods, gained special attention in the materials modification field dedicated to implants. MAO is based on the deposition of an oxide layer on the anodic surface of a metallic substrate using an electric field to assist in the ionization of elements in an aqueous electrolyte and their diffusion into the metal. Compared to standard oxidation, MAO is performed under higher current and voltage conditions. By adjusting process parameters such as electrical parameters, electrolyte components, oxidation time, and temperature, highly porous, well-adhered layers with topography and chemical composition that promote osseointegration and antibacterial activity can be achieved. An effective approach to improving titanium osseointegration is to create a bioactive coating on its surface with a composition similar to human bone. Enhancement of antibacterial properties, on the other hand, focuses on incorporating metal ions, nanoparticles, or antibiotics. Therefore, electrolytes used in MAO typically consist of calcium and phosphate compounds with bioactive and antibacterial additives such as silver, gold, copper, zinc, and antibiotics. Studies were conducted to investigate the effect of various MAO process parameters, such as applied voltage, current density, and time process, as well as electrolyte composition, on titanium/titanium alloy surface characteristics in terms of structural, chemical, physical, biological, and/or mechanical properties. The results indicated that the optimization of the MAO process increases the biocompatibility and biological activity of the titanium implant, which plays a significant role in improving applicational effectiveness.