Friction characteristics of rapid spreading surface with annular microtexture at reciprocating contact interface

The design of microtextures on the tribopair surface is an effective method of improving tribological properties. Circular micro-dimples arranged in a certain way on the reciprocating contact surface are the commonly used shape. Inspired by the rapid spreading characteristics of the bionic structure, two types of annular microtextures with circular convex (AC) and hexagonal convex (AH) were designed. Compared with the circular microtextured surface, the friction coefficients of the AC and AH microtextured surfaces were both reduced by more than 10 % and the wear depths were both reduced by more than 4 %.The annular microtextured surfaces had less plastic deformation, fewer scratches on the worn platform and less spalling at the microtextured edge. Comparing the contact angles and spreading diameters of the different microtextured surfaces before and after the test, the annular microtextures showed small changes in wettability. It could enhance the capillary effect and reduce the influence of the pinning effect. This rapid spreading characteristic effectively promoted the formation of a continuous lubricating oil film in the friction contact zone, especially at the dead center, providing an efficient transport capacity for the lubricant to the reciprocating contact interface.