Nanotribologia de Filmes Finos de Carbono Amorfo - Introduo. - Filmes base de carbono: - CN - B 4 C - Carbono Amorfo - Tribologia: - Atrito - Desgaste - Perspectivas: Superhard Materials: C B N B4CB4C c-BN -C3N4-C3N4 diamond C 3 N 4 /ZrN superlattice deposited by dc-sputtering 21 bilayers: ZrN 0.6 (5.4 nm thick) r = 6.8x10 22 at/cm 3 and C 3 N 4 (1.8 nm thick) r = 1.6 x10 23 at/cm 3. M.L. Wu, F.L. Freire Jr. et al., Appl. Phys. Lett. 76, 2692 (2000). Why are we studying tribology in such a scale? MEMS MEMS A small gear built up at the Laboratorio Nacional de Luz Sincroton Protective coatings for hard magnetic disks Filmes de a-CF (N) Carbon-based films: sp 3 2 H ta-C ta-C:H a-C:H sputtered a-C(:H) -Friction of fluorinated carbon films: -AFM calibration. -Film properties. -Results. Tribology Letters 15 (2003) 177 Tribology Letters 15 (2003) 177 -Wear of carbon films: - a-C:H; a-C:H:F; ta-C films and nanostructured carbon films. -Micro and nanoscale wear. Diamond & Related Materials 12 (2003) 2195 Films deposited by rf-PECVD using C 2 H 2 -CF 4 mixtures Chemical composition and atomic density by IBA C 2 H 2 partial pressure (%) Composition (at.%) Atomic density (10 23 atoms/cm 3 ) CHFO XPS F = 35 at.% F = 10 at.% = 70 0 a-C:H film F = 0 at.% = 72 0 R a = 2.4 nm a-C:F film F = 35 at.% = 95 o Ra = 2.0 nm = 72 o = 90 o = 72 o = 90 o = 95 o Friction model FLFL Ln (v) m> F c m= F c m< F c In order to fit our experimental data with Riedos model we need to calculate or measure the parameters v a, v b, m, P s, P etc. (contact diameter) (time to built up a capilary bridge 25 s) a is obtained with the use of the Johnson-Kendal-Robertson Experimental data Riedos model The velocity dependence of friction is strongly The velocity dependence of friction is strongly influenced by the capillary condensation of water. influenced by the capillary condensation of water. The friction can be correlated with the materials The friction can be correlated with the materials contact angle. contact angle.Conclusions: Wear at nanometer scale Mecanismo de desgaste: H 3 BO 3