Investigation of adsorbed protein and passive films on hydrodynamic lubricated steel slider surface

The adsorbed bovine serum albumin (BSA) and passive tribofilms, which were formed on a hydrodynamic lubricated steel slider surface with BSA-PBS aqueous solutions, were investigated. The morphological features and chemical structure of the slider surfaces were analyzed using SEM, AFM and XPS. Results show that the protein adsorption is spread over the steel surface heterogeneously. The films are apparently characterized by two layers. The top layer is in the form of protein agglomerates embedded in a gel-like matrix, and the bottom layer contains Cr+3/Fe+2/Fe+3-rich passive oxides. The relations between corrosion and adsorption are discussed. The BSA adsorption gets escalated due to the presence of corrosion. The organic-inorganic composite films can work as a solid lubricant to reduce friction.