Abstract:This paper reports the use of micro-arc oxidation(MAO) to prepare porous oxide coatings on the surface of titanium and large plastic deformed titanium. The bio-tribological properties of the MAO coatings were evaluated under different lubrication medium conditions, namely dry friction, stimulated body liquid, and calf serum. The effect of structure refinement of the titanium substrate on the friction wear properties of the coating surface was also investigated. The MAO coating obtained from large plastic deformed titanium exhibits higher abrasion resistance than the MAO coating on titanium because of improved friction wear properties. To be more specific, the structure refinement of the titanium substrate results in more crystal defects and provides more energy for nucleation on the MAO coating,which makes the TiO2 coating formed through the reaction harder, the coating surface more compact, uniform, and smooth.The friction coefficient and degree of wear of the MAO coating formed from large plastic deformed titanium under calf serum lubrication are better than those under dry friction and stimulated body liquid. This finding could be attributed to more effective lubrication and cooling, as well as to the roles of the coatings formed on the friction surface through chemical reaction and physical adsorption under calf serum lubrication.