Lubrication of surface oxidized Co–Cr thin films by phosphoric and phosphorous acid esters

Abstract Phosphoric and phosphorous acid esters have been applied to surface oxidized Co–Cr thin films, and their lubrication performances are investigated. Tricresyl phosphate, phosphoric and phosphorous acid esters with long alkyl chains are found to be very effective in reducing friction and wear of thin films. Such excellent lubrication performances could be attributed to their strong adsorption to the oxide surfaces and large cohesive energy between the lubricant molecules. These results are discussed in detail.