Nanomechanical and nanotribological properties of carbon-based thin films: A review

Carbon-based thin films possess unique and adjustable combination of properties such as high hardness and wear resistance, chemical resistance and good tribological performances. Among critical variables to tailor a-C film’s properties for specific application is the distribution of the carbon hybridization states (sp1, sp2 and sp3 bonds), the atomic H content, the content in dopants such as Si, F, N, B and O. Here we focus on: (i) a-C and hydrogenated amorphous carbon (a-C:H) films with a mixture of sp2 and sp3 bonding, highly sp3-boned material (ta-C) and sp2-bonded carbon, (ii) carbon nitride (CNx) coatings and (iii) metal/amorphous carbon (a-C:M) composite films.The study is focused on the review of the nanomechanical properties and analysis of the nanoscratching processes at low loads to obtain quantitative analysis, the comparison of their elastic/plastic deformation response, and nanotribological behavior of the a-C, ta-C, a-C:H, CNx, and a-C:M films. For ta-C and a-C:M films new data are presented and discussed.