ve čtvrtek 17. března 2010 od 13:00 hodin v učebně č. 345
Ing. Tomáš Polcar, Ph.D.
Department of Control Engineering, Faculty of Electrical Engineering,
Czech Technical University in Prague, Technická 2, Prague 6, Czech Republic
Transition metal dichalcogenides (TMD) are suitable as solid lubricants due to their anisotropic layered structure, where the adjacent lamellae with strong covalent bonding interact through relatively weak van der Waals forces. They are usually applied as solid lubricant, as oil additives or as thin films to decrease friction energy losses in mechanical systems. In general, the main challenge in the development of the self-lubricant coatings based on TMD is to improve their mechanical properties and resistance to environment attacks providing the sliding is driven exclusively by TMD.
This talk will show two fundamentally different concepts of modern self-lubricant coatings. The first design could be considered as traditional: the TMD films are doped by carbon. The main attention is aimed at qualitative description of surface and sub-surface modification of the films at the result of sliding process. Based on thorough analysis of the worn surfaces, two features emerge: self-adaptability, where originally randomly oriented TMD phase becomes well oriented (i.e. with basal planes parallel to the surface), and limited role of carbon in the contact. The second concept deals with combination of a hard TiN matrix deposited by reactive magnetron sputtering, and fullerene-like TMD nanoclusters, which are directly injected into the growing TiN film. Despite the embryonic stage of the process development limiting in many ways the final properties of the film, the mechanical and tribological properties seem to be promising. The fullerene-like structure of TMD is well maintained and the composite hardness is relatively high compared to competitive self-lubricant coating designs.
Srdečně zveme všechny zájemce z řad studentů, učitelů i odborné veřejnosti.
Doc. RNDr. Dušan Novotný, CSc.
Univerzity J. E. Purkyně
České mládeže 8
400 96 Ústí nad Labem
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