Fabrication and tribological properties of self-assembled monolayers of alkanethiols on nickel substrates

Abstract

Self-assembled monolayers (SAMs) are considered as the potential lubricants and can be used to control the adhesion and the wear in micro-electromechanical system. In this study, alkanethiols SAMs of single component and mixed alkanethiols SAMs with different alkyl chain lengths were fabricated on the surfaces of nickel (Ni) substrates by the solution deposition method. The surface morphology and the wetting property of bare Ni substrate and different SAMs were characterized by the atomic force microscopy and water contact angle measurement. Moreover, a ball-on-plate tribometer was selected to measure the tribological properties of bare Ni substrate and different SAMs. The surface free energy of Ni Substrate decreased significantly after the surface modified by different alkanethiols molecules, which effectively reduced the surface adhesion of Ni substrate. The friction coefficients of Ni substrates coated with different SAMs were much lower than that of bare Ni substrate. In addition, the mixed alkanethiols SAMs had the greatest lubricity and wear resistance compared to other alkanethiols SAMs of single component.