| AVS 58th Annual International Symposium and Exhibition | |
| Tribology Focus Topic | Thursday Sessions |
| Session TR-ThP |
| Session: | Tribology Focus Topic Poster Session |
| Presenter: | Francisco Javier Flores-Ruiz, CINVESTAV-Unidad Queretaro, Mexico |
| Authors: | F.J. Flores-Ruiz, CINVESTAV-Unidad Queretaro, Mexico F.J. Espinoza-Beltran, CINVESTAV-Unidad Queretaro, Mexico M.O. Vazquez-Lepe, CINVESTAV-Unidad Queretaro, Mexico A. Herrera-Gomez, CINVESTAV-Unidad Queretaro, Mexico |
| Correspondent: | Click to Email |
Diamond-like carbon (DLC) films are promising materials for dry-contact applications where resistance to surface damage or lubricating performance is required. In the present work, the structure of 3 and 10 nm Focus Cathodic Arc (FCA) carbon films and 3 and 10 nm plasma carbon films grown on Si(100) was studied by angle-resolved X-ray photoelectron spectroscopy (ARXPS). The concentration and distribution of sp2 and sp3 carbon within the film was assessed with methods described elsewhere [i]. Atomic force microscopy (AFM) with a silicon tip was used to study the friction coefficient μ on the nanoscopic scale. It is defined by the Amonton law, µ=FL/FN, where FN and FL are the normal and the lateral force applied to a probe [ii]. The calculation of the normal and lateral force applied during the process of sliding the tip over the sample was done according to the methodology proposed by Carpick [iii] . The results suggest a relationship between the chemical structure and the tribological performance for each film tested. The films grown by FCA presented the best tribological performance (μ~0.02) compared to films grown by plasma (μ~0.06) indicating a direct link between the distribution of sp2 and sp3 carbon and the nanoescale friction coefficient. Since during the friction tests there was no evidence of damage or wear on either the surface or the tip, the conventional interpretation for the origin of friction proposed by Bowden and Tabor [iv] grossly underestimates the energy loss in the sliding process. On the other hand, the energy loss can be quantitatively explained in terms of heat generation [v]. The tribological performance analysis indicates that the friction is related to the adhesion force between tip and sample. However, the friction coefficient values do not show significant changes as the strength of adhesion varies, indicating that the value of the friction coefficient depend on the contributions of atomic bonds at the surface.
[i] A. Herrera-Gomez, et al., "Structure of ultra-thin diamond-like carbon Films grown with Filtered cathodic arc on Si(001)”. Analytical Sciences 26, pp. 267 (2010).
[ii] G. Amonton, “De la resistance cause´e dans les machines”. Mem. Acad. R. A, 275 (1699).
[iii] R. W. Carpick, “Scratching the Surface: Fundamental Investigation of the Tribology with the Atomic Force Microscopy”. Chemical Reviews, 97, pp. 1163 (1997).
[iv] F. P. Bowden, and D. Tabor, “Friction and Lubrication of Solids”. Oxford University Press, pp. 52 (1964).
[v] J. Luo, Y. Hu, S. Wen (Editors), “Physics and Chemistry of Micro-Nanotribology.” ASTM-International, West Conshohocken, PA, USA. Chapter 9, pp. 167 (2009).