Characteristics of Progressive Damage of ZnO Nanowires during Contact Sliding under Relatively Low Loads

Figure 5

SEM image of the wear track on the ZnO nanowire specimen after the friction test under (a) 2 mN, (b) 4 mN, and (c) 6 mN applied load after 1–20 cycles of contact sliding. (⊳: fracture of ZnO nanowire with large diameter, →: fracture of ZnO nanowire with small diameter, dotted regions: the severe damage and compacted region of ZnO nanowires).