Microscopic stick–slip in friction force microscopy

摘要: Friction force measurements were performed on 2-hydroxy stearic acid (2-HSA) and 12-hydroxy (12-HSA) coated silica surfaces in air using an atomic microscope. The 2-HSA displayed viscoelastic behaviour with a yield point as the static–dynamic friction transition. Steady sliding motion was replaced by microscopic stick–slip at lower velocities higher loads. Stick–slip successfully described fitted to phenomenological model ascribed interfacial material melting freezing periodic cycles. periodicity is of same order contact diameter. 12-HSA did not experience exhibited steady over entire load velocity regime. We attribute these observations difference molecular configuration, shear strength adsorption density layers.