Frictional anisotropy of tilted molybdenum nanorods fabricated by glancing angle deposition

• Nanostructured thin film (NSTF) consisting of tilted Mo nanorods was fabricated.
• NSTF exhibited strong frictional anisotropy and high resistance to deformation.
• COF values were higher against the direction of nanorods tilt than along the tilt.
• Surface roughness contributes to friction anisotropy at low loads.
• Deformation mechanisms of nanorods contribute to friction anisotropy at high loads.

The frictional anisotropy and deformation behavior of a nanostructured thin film (NSTF) consisting of tilted molybdenum (Mo) nanorods was investigated. The NSTF exhibited strong frictional anisotropy and the coefficients of friction were larger when sliding against the direction of nanorods tilt as compared to sliding along the tilt direction, reaching a maximum of ~35% difference. Frictional anisotropy at low loads is attributed to the anisotropy in surface roughness, whereas, at high loads, it is attributed to the difference in the deformation mechanism of nanorods when sliding along and against the direction of nanorods tilt. Furthermore, no deformation was detected after the scratch even after heavy scratches, indicating strong resistance of nanorods to plastic deformation.