Tribological characterization of microarc oxidized alumina coatings for biological applications

Coatings with high wear and corrosion resistance are desirable in tribological and biological applications. In an attempt to develop such coatings, we used microarc oxidation (MAO) method to generate noble coatings of alumina on aluminum alloys. This paper reports our tribological investigations on these coatings with a pin-on-disk tribometer in synthetic biofluid. The frictional behavior and wear mechanisms were studied through surface characterization using a scanning electron microscope and a surface profilometer. It was found that the MAO coatings were highly wear resistant in the biofluid environment. The frictional behavior depends on the relative hardness of the ball-on-disk materials. The increased α-Al₂O₃ and γ-Al₂O₃ phases with an increase in the current intensity were found to reduce the friction.