Contribution of hardness and work hardening to the wear resistance of Pt-based metallic surfaces revealed by nanoscale reciprocating sliding

The contribution of hardness and work hardening to the wear resistance of Pt-based metallic surfaces under reciprocating sliding contact have been investigated by atomic force microscopy. The atomically flat surfaces of the Pt-BMG and Pt (1 1 1) enable the sliding friction to be a single-asperity contact. It was found that at low loads where the sliding contact was primarily elastic, the Pt(1 1 1) produced a larger adhesion than the Pt-BMG, which was ascribed to the larger mixing enthalpy between counterbodies. When the sliding contact entered into wear regime at high loads, the Pt-BMG that displayed a high hardness nearly-six times of Pt (1 1 1) was expected to have a higher wear resistance according to the Archard's law, yet the Pt(1 1 1) actually performed better. We further explore that the work hardening mechanism associated with dislocated-mediated deformation contributes to the high wear resistance of Pt(1 1 1), as corroborated by a significant friction force decrease within scratched region on Pt(1 1 1) surface. However, such a hardening mechanism is not expected to operate in PtBMG due to the lack of mobile structural defects like dislocations, as confirmed by the little change in friction force between scratched and unscratched regions.

Automated summary

The contribution of hardness and work hardening to the wear resistance of Pt-based metallic surfaces under reciprocating sliding contact were investigated using atomic force microscopy. It was found that Pt(1 1 1) exhibited a larger adhesion than Pt-BMG at low loads, while Pt-BMG showed higher hardness and was expected to have higher wear resistance at high loads. However, Pt(1 1 1) actually performed better, possibly due to the work hardening mechanism associated with dislocated-mediated deformation.