Surface mechanical proprieties of materials: a brief review

In many fields such as aerospace, automotive, microelectronic, and biomedical applications the surface mechanical properties are crucial. Although in the last 30 years, the nanoindentation technique has allowed us to explore the surface mechanical properties of materials, few papers have reported a general overview of the hardness and elastic modulus of surfaces. In this work, we report the surface mechanical properties of the main polymers, ceramics, metals, and biomaterials. We report the hardness (H) and elastic modulus (E) estimated by nanoindentation using the Oliver Pharr method. We also include a qualitative evaluation of the material's H/E ratio, which is an indicator of wear resistance. In the mapping of mechanical properties, the new nano-structured materials and graphene are very interesting because they show, in contrast to traditional materials, very high hardness and relatively low elastic modulus, therefore a high H/E is an indication of good mechanical resilience.