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 (sp(1), sp(2) and sp(3) 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 sp(2) and sp(3) bonding, highly sp(3)-boned material (ta-C) and sp(2)-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. (C) 2009 Elsevier Ltd. All rights reserved.