Measurement of the mechanical properties of carbon nitride thin films from the nanoindentation loading curve

Mechanical properties such as Young's modulus of hard highly elastic carbon nitride films are difficult to determine by nanoindentation from the conventional analysis using the unloading curve as proposed by Oliver and Pharr due to the high elastic recovery of these materials, resulting in unexpectedly low modulus values. An analysis of the nanoindentation loading curve was used to determine the Young's modulus of carbon nitride thin films. The method also enables determination of the maximum penetration depth where the coating only properties can be achieved. Carbon nitride thin films were deposited by RF magnetron sputtering using graphite as a target material. Nanoindentation testing on the samples was carried out using a CSM(TM) nanohardness tester. The Young's modulus value of carbon nitride films, analysed from nanoindentation loading curves, was approximately 822 GPa, which is much higher than the value 170 GPa obtained from the conventional analysis using the unloading curve. (C) 2003 Elsevier B.V. All rights reserved.