The potential for
the use of copper coatings on steel switching
mechanisms is abundant owing to the high conductivities and corrosion
resistance that they impart on the engineered assemblies. However,
applications of these coatings on such moving parts are limited due
to their poor tribological properties; tendencies to generate high
friction and susceptibility to degradative wear. In this study, we
have fabricated a fluorinated graphene oxide–copper metal matrix
composite (FGO-CMMC) on an AISI 52100 bearing steel substrate by a
simple electrodeposition process in water. The FGO-CMMC coatings exhibited
excellent lubrication performance under pin-on-disk (PoD) tribological
sliding at 1N load, which reduced CoF by 63 and 69%, compared to the
GO-CMMC and pure copper coatings that were also prepared. Furthermore,
FGO-CMMC achieved low friction and low wear at higher sliding loads.
The lubrication enhancement of the FGO-CMMCs is attributed to the
tribochemical reaction of FGO with the AISI 52100 steel counterface
initiated by the sliding load. The formation of an asymmetric tribofilm
structure on the sliding track is critical; the performance of the
FGO/Cu tribofilm formed in the track is boosted by the continued fluorination
of the counterface surface during PoD sliding, passivating the tribosystem
from adhesion-driven breakdown. The FGO-CMMC and GO-CMMC coatings
also provide increased corrosion protection reaching 94.2 and 91.6%
compared to the bare steel substrate, allowing for the preservation
of the long-term low-friction performance of the coating. Other influences
include the improved interlaminar shear strength of the FGO-containing
composite. The excellent lubrication performance of the copper matrix
composite coatings facilitated by FGO incorporation makes it a promising
solid lubricant candidate for use in mechanical engineering applications.