To understand the macroscopic tribology, the detailed microscale mechanisms, e.g. microstructure and surface evolution, have to be investigated. Macroscopic wear resistant surfaces rely on the tailored evolution of surface layers, i.e. microstructure evolution, which reduce the friction coefficient and prevent wear particle formation.
We study a microsaperity contact: pearlitic steel (with 1.15% carbon), which consists of hard cementite lamellae in a soft ferrite matrix, was prepared by conventional metallography. We scratched the surface in a nanoindenter with spherical diamond tips of different radii and with varying forces and velocities. Afterwards the surfaces are covered by a protective layer of Ni. Tribology induced mechanical surface layers underneath the scratches are investigated after target preparation in the scanning electron microscope and transmission microscope. We quantify the cementite lamellae fracture and bending. Further micromechanical experiments such as fracture toughness testing and bending tests are used to investigate cementite deformation. In addition we discuss the tribological surface layer thickness and morphology as a function of the loading.