Effect of nitrogen ion-implantation on the tribological properties and hardness of TiN films

The tribological properties and ultra-micro hardness of ion-implanted TiN films grown by a commercial PVD technique on steel substrates are addressed. The ion-beam treatment was performed using non-mass analyzed nitrogen beam with energy of 100 keV to nominal doses ranging between 0.5 and 6 x 10(17) ion cm(-2). The analytical techniques employed by us included: Rutherford backscattering (RBS) for depth profile determination, pin-on-disc tests and nano-indentation tests. It was found that the bombardment with nitrogen ions considerably improved the friction coefficient of TiN films except for layers modified with the highest does (6 x 10(17) ion cm(-2)). Examination of virgin and ion-beam bombarded specimens by the ultra-microhardness method revealed differences in mechanical characteristics before and after indentation. The surface deformation results are discussed from the point of view of irradiation induced defects. The hardness data seem to be affected by variations in nitrogen content due to bombarding with nitrogen ions. The analysis of indentation load-depth curves is supported by considerations based on energy principle of indentation. (C) 1998 Elsevier Science S.A. All rights reserved.