Effect of Contact Geometry on MoS 2 -based Dry Film Lubricants

MoS₂-based dry film lubricants are widely used in aerospace mechanisms that have varied contact geometries. Standard tribotests for dry film lubricants simplify real geometries as either point or line contact to facilitate comparison of different materials or conditions. However, it remains unclear whether the results of a tribotest with one contact geometry can be generalized to tests or mechanisms with different contact geometries. To assess the effect of contact geometry, we measured friction and wear of three MoS₂-based dry film lubricants using block-on-ring and pin-on-disk tests with matched initial Hertzian contact pressure and linear velocity. Friction and wear magnitudes, as well as comparative trends among the dry film lubricants, differed between the two contact geometries. These findings encourage future studies to consider more than just point contact tribotests when evaluating MoS₂-based dry film lubricants.