The influence of APTES interlayer on the assembly and tribological properties of graphene coatings on titanium substrate

In order to improve the tribological properties of titanium substrate, self-assembly technique was used to prepare a graphene-silane coating: RGO-APTES coating on titanium substrate. The γ-aminopropyltriethoxysilane (APTES) was used to prepare a self-assembled APTES coating as a function of adhesive interlayer, aiming to improve the assembly efficient for graphene coating. The influence of that interlayer on the assembly and tribological properties of graphene coatings on titanium substrate was investigated. Morphology, thickness, chemical characteristic and tribological tests were utilized to investigate the assembly process and tribological properties of coatings. The results show that: (1) the pH values of APTES aqueous solution plays an important role in the molecule orientation of the APTES interlayer, and thus the properties of graphene coating is influenced. When pH is approximately 8.5, the molecule orientation of the interlayer is consistent, so that it has improved adsorption effect on graphene sheets and the graphene coating is uniformly distributed and well-covered; (2) the thickness influences the tribological properties of graphene-APTES coating -- single layered APTES interlayer provides a stronger interlayer strength. The obtained RGO-APTES2 samples have novel friction reducing and wear resisting properties, and can be applied on the surface of titanium substrate as lubricating coating.