Development of a bending-stress-controllable micro-clamp and applications in nanowear study of polyimide terephthalate

Inner stress that exists in most natural and artificial materials, such as rocks, coatings, glasses, and plastic products, has a significant impact on their tribological properties at any length scale. Here, we designed a bending-stress controllable micro-clamp that can be applied in a high-vacuum atomic force microscope with limited chamber space for the investigation of stress-dependent nanowear behavior. By accurately quantifying the bending degree of the sample in different directions, the mutual transformation and adjustment of tensile or compressive stress could be realized. The stability of the micro-clamp structure was further verified by simulating the bending deformation state of the sample through Ansys calculations. The maximum applied scratch area on the bended sample surface where the variation of bending-induced stress below 5% was defined by the Ansys simulations. The consistency of polyimide terephthalate (PET) wear inside this defined region under both bending-free and bending states verified the stability and reliability of micro-clamp. Finally, the designed micro-clamp was applied to study the effect of bending deformation on friction and wear of PET in the atomic force microscope tests, where the tensile stress generated with bending deformation was found to facilitate the nanowear of PET material sliding against a diamond probe.