The relationship between friction and wettability in aqueous environment

In this study, the influence of surface wettability (θ) and interfacial energy (γ) on the coefficient of friction (f) of tribopair surfaces in aqueous environment was investigated using a tribotester. The wettability behaviour of various tribopair surfaces [hydrophilic (HL) and hydrophobic (HB)]: (HL–HL), (HB–HB) and (HB–HL) was characterized by friction properties in water and aqueous two-phase lubricants (water + additive). The results show that the level of wettability of the tribopairs [the so-called delta wettability, Δθ = (θDisc − θPin)] is related to friction coefficient (f) in aqueous environment. In view of recent results, we conclude that both the interfacial energy and wettability of tribopair surfaces adequately characterize the lubrication processes.