单晶蓝宝石衬底表面微结构对摩擦性能的影响OA

In previous studies,conducting in-situ friction measurement by atomic force microscope have remained challenging.Two-dimensional friction-force atomic force microscopy(2DFF-AFM)is a method that enables friction measurements on material surfaces at the two-dimensional scale using atomic force microscopy.By combining the torsional signal of the cantilever with the Z-direction piezoelectric feedback corresponding to the bending signal,this method achieves microscopic friction measurements at arbitrary scanning angles.This study used 2DFF-AFM method to investigate the friction behavior between silicon probes and two different substrates(amorphous silicon oxide and single-crystal sapphire)under atmospheric conditions.The results show that friction on amorphous silicon oxide is isotropic when measured with a silicon probe.Friction on single-crystal sapphire comprises an isotropic component and an anisotropic component with 90° periodicity which arises from single crystal silicon of tip,the high hardness of sapphire wears through the native oxide layer of the silicon tip,exposing the underlying single-crystal silicon.In addition,under the influence of adsorbates,both the isotropic friction signal and 90° periodic anisotropic friction signal exhibit a non-monotonic trend with increasing load,initially decreasing and then increasing.After thermal treatment of single-crystal sapphire substrates,sub-nanometer steps appears on the surface,and friction measurements show that sapphire exhibits a friction signal with a period of 180°.This directly indicates that the step structure on the sapphire surface significantly affects the anisotropic friction behavior.The 2DFF-AFM method provides an effective theoretical and practical approach for separating friction forces from different sources at the interface.