Effect of bovine serum albumin aqueous solution on steel slider surface under hydrodynamic lubrication

• Direct observation of effects of BSA aqueous solution on bearing surfaces.
• BSA adsorption characterized by continuous thin layer and discrete protein aggregate.
• Corrosion occurred first in the inlet region and moved to the outlet.
• A new two-medium approach developed for adsorption film thickness measurement.

Lubrication and adsorption behaviours of bovine serum albumin (BSA) aqueous solution were studied using an optical slider-bearing tester. The lubricated contact consisted of a stationary steel slider and a moving glass disc. Interferometry was employed to measure the film thickness. Results showed that film thickness increased with increasing speed and decreased with increasing load. During the tests, a strip of corrosion on the steel slider surface grew from the inlet to the outlet and quick corrosion occurred at high sliding speeds. Corrosion was found to promote protein adsorption. Two types of adsorption, namely, continuous thin layer and discontinuous protein aggregate, were generated on the slider surface. A new approach based on the difference in optical film thickness formed with two different media was proposed for the measurement of adsorption film thickness. Moreover, results showed that high sliding speeds and low loads favored the growth of adsorbed film.