Microstructure and Dry Sliding Tribological Behavior of Microarc Oxidation Coating Formed on Ti6Al4V against Steel
A nanostructured TiO2 dominated ceramic coating was fabricated on Ti6Al4V by microarc oxidation (MAO). The coating with about 30 μm thickness is porous in the outer layer and compact in the inner layer, mainly composed of rutile and a small amount of anatase TiO2, both in nano grain structure. The hardness and elastic modulus of the compact layer in the coating are about 8.5 GPa and 87.4 GPa. The adhesion strength is about 70MPa. The friction coefficient of the polished coating sliding against GCr15 steel is as low as 0.2, which is clearly superior to that of the unpolished one. This is attributed to the low surface roughness. However, the oxidation wear mechanism occurring at the later stage of wear tests leads to a gradual increase of friction coefficient.
Wei Pan and Jianghong Gong
Y. M. Wang et al., "Microstructure and Dry Sliding Tribological Behavior of Microarc Oxidation Coating Formed on Ti6Al4V against Steel", Key Engineering Materials, Vols. 336-338, pp. 1734-1736, 2007