Effects of Temperature on Microstructure and Tribological Performance of a-CNx Films Prepared by Pulsed Laser Deposition

Amorphous carbon nitride (a-CNx) films were deposited onto silicon wafers at temperatures from RT up to 600 degrees C by using pulsed laser deposition technique (PLD). The composition, morphology and microstructure of the CNx films were characterized by X-ray photoelectron spectrum (XPS), scanning electron microscopy (SEM) and Raman spectrum. The tribological performance of the films was investigated using a ball-on-disk tribometer. With increasing the deposition temperature ranging from RT to 400 degrees C, the N content of films dropped from 36 at% to 22 at%, the ratio of N-sp3 C bonds, hardness and friction coefficient of the film decreased. Further increase of deposition temperature led to the lack of nitrogen and the increasing degree of order in ringed sp2 C=C bonds of the amorphous carbon film. The mechanical and tribological performances became worse. The film deposited at 300 degrees C showed a low friction coefficient of 0.11 and a preferable wear resistance of 1.65x10-7mm3N-1m-1 in humid air.