Investigating the fracture resistance and adhesion of DLC films with micro-impact testing

Micro-impact testing, a new repetitive contact testing technique has been developed to simulate the fatigue conditions which coatings experience in service more closely than existing testing methods. Diamond-like carbon (DLC) films deposited on silicon under different RF powers have been investigated with the new technique. The technique provides a new approach to the investigation of the fracture properties of thin films. Single-point impact data for brittle materials, such as DLC films, show an initial period of damage generation followed by catastrophic failure. The time-to-failure and the overall change in probe depth during a test are measures of the resistance of the coating to fracture. Differences in impact resistance between the DLC films are explained in terms of variations in film toughness and adhesion strength, which, in turn, are a function of the DLC deposition conditions. (C) 2002 Elsevier Science B.V All rights reserved.