Ultra-low friction properties of DLC lubricated with ester-containing oil —Part 1: Pin-on-disc & SRV friction tests—

This paper presents a material combination that reduces the friction coefficient significantly to an ultra-low regime (below 0.05) under boundary lubrication, as indicated by the results of pin-on-disc toric sliding tests and reciprocating sliding tests (SRV). This ultra-low friction performance was obtained by sliding hardened steel pins on a hydrogen-free diamond-like carbon (DLC) film (a-C) lubricated with a poly-alpha-olefin (PAO) oil containing an ester additive. Moreover, the friction coefficients of a-C couples were substantially lower than those of hydrogen-containing DLC couples and that of an a-C/steel combination.