Antifrictional Effect of Biobased Fillers on Bioceramic Alumina

Nanoporous coatings suggest new opportunities for anodic alumina (Al2O3) as an innovative bioceramic material. Despite its hardness, the wear of bioceramic coatings presents a major problem in many applications, including biomedicine. In biological systems, wear must be avoided. In this study, friction was evaluated on bioceramic coatings using biobased fillers. Several lipids including oleic acid, stearic acid, lauric acid and trilaurin were chosen for impregnation on anodized 6082 and 7075 alloys to evaluate the possible friction conditions of the biomaterials in the body. Lipids improved the friction resistance of bioceramic coatings up to 10 times when compared to solid lubricants based on polytetrafluoroethylene (PTFE). Biobased fillers sustained up to 10000 friction cycles with a Coefficient of Friction (COF) below 0.1 before abrasion, especially on 7075 alloys. According to friction and scratch results, oleic acid had the highest friction and wear resistance on 6082, while trilaurin showed better resistance on 7075 alloy against corundum. The ability to reduce friction and wear for stearic acid was insufficient under high loads. Combining the optimal biobased filler with nanoporous Al2O3 can further improve tribological performance for biomedical purposes.