Abrasive properties of ZnO: Influence of different nanoforms

This study concerns eight samples of ZnO powders, which can be classified in three categories: 3D-structure samples (ellipsoids, flowers), 2D-structure samples (commercial sample, nanosheets), 1D-structure samples (nanorods; short, long and irregular needles). Apart for the commercial sample, the others were synthesized through wet chemistry processes. The morphological and structural features of the ZnO powders were investigated with the purpose to understand how the friction behaviour is affected by the materials intrinsic properties. The tribological analysis was performed using a pin on disc tribometer, studying the influence of the material properties by a multivariate statistical approach. Results show that the abrasive nature of ZnO nanoforms is correlated with the crystallite dimensions. Spherical particles cause a higher damage on surfaces at the interface, with a consequent major change in the roughness. In the case of 1D-structure samples, the friction coefficient is directly proportional to the aspect ratio of the particles.