1-hexyl-3-methylimidazolium hexafluorophosphate as oil additive for the lubrication of steel-steel contacts and its influence on the running-in and wear-in periods - Rodriguez, R.G.; Rodriguez, J.L.V.; Battez, A.H.; Asedegbega, E.; Garrido, A.H.; Perez, A.T. (American Society of Mechanical Engineers, Tribology Division, TRIB, 2011)