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RESEARCH PROPOSAL STUDY OF LAYERED MoS 2, WITH MoTe 2, AND MoSe 2 Warren Courtney University of Waterloo March 29, 2006.

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Presentation on theme: "RESEARCH PROPOSAL STUDY OF LAYERED MoS 2, WITH MoTe 2, AND MoSe 2 Warren Courtney University of Waterloo March 29, 2006."— Presentation transcript:

1 RESEARCH PROPOSAL STUDY OF LAYERED MoS 2, WITH MoTe 2, AND MoSe 2 Warren Courtney University of Waterloo March 29, 2006

2 Background  Numerous studies have looked at the tribology of multi-layered dry lubricants, for myriad reasons (ref 1, 2, 3, 8)  Studies have also been done on the orientation of molecules in the lubricating layers to determine the effects. Dramatic increase in friction can occur when molecules align (ref 9)  This study proposes looking at a nano-structured material composed of layers of MoS 2, MoTe 2, and MoSe 2 in which the material are deemed to have similar properties but different crystal structures which should reduce friction by not allowing co- incidence structure.

3 Nanoscale friction  Graph of atomic force microscopy probe moving across a smooth surface of NaCl (  Proposed mechanism based on Tomlinson’s model of atomic friction ( the sample surface

4 physics Phononic friction  As surfaces pass over one another the theory of friction indicates that attachments are made and broken between materials resulting in the production of phonons  It should be more difficult for multilayer materials to pass over one another since there are more ways for the atoms to move and interact and create heat and phonons  Such "phononic" friction is particularly great when the surface atoms are equally spaced, and when they are aligned with the counter face atoms upon which they are sliding.

5 ref4 Lince, R. L. and Frantz, P.P. Structure of MoS 2  Structure of MoS 2 Strong bonds within layers and very weak bonds between layers  Similar structures are proposed for MoSe 2 and MoTe 2 However the structure are altered due the size differences in the dichalcogenes

6 Crystal Structures Analogous to Molybdenum Disulphide  Prototypical structure: 

7 Geike, T. Popov, v. L. ref 1 Multilayer graphite structure Friction is reduced each time a new layer starts to move relative to the others

8 Sandia National Laboratories Nano-tractor to measure very low frictional forces This image obtained using a scanning electron microscope shows a "nano- tractor" that can measure ultra low frictional forces as it creeps along a surface. In the centre of the device is a tangential-force actuation plate, flanked by two electrostatic "clamps" that respond to an applied voltage.

9 Hu, J. J., Bultman, J. E., Zabinski, J. S. ref 7 Preparation of Nanolayered Molybendum Dichalcogenides  High purity films can be created by laser ablation using an excimer laser UV radiation at 248 nm wavelength, 20 ns duration 50 Hz.  Characteristics and composition of the layers will be determined with x-ray photoelectric spectroscopy  Samples for testing will consist of layers of MoS 2 with MoSe 2 ; MoS 2 with MoTe 2 ; MoSe 2 with MoTe 2 ; and MoS 2 alone as a standard for comparison

10 CSM Instruments SA Testing of Multilayer Molybdenum Dichalcogenides  Initial testing will be performed at the nanoscale using the nanotractor shown previously  Should result show promise a further set of testing will be conduced in a nitrogen purged pin on disc tribometer

11 Environmental Testing  Further test comparisons will be made after 200 hours conditioning in environments containing air at relative humidity of 15%, 25%, 50%, and 75% relative humidity in air at 35 o C; testing will be performed in the conditioning environment

12 References 1.Geike, T., Popov, V. L. Tribology International 39 (2006) pp , Multi-layer models of friction between solids 2.Lince, J. R. Tribology Letters, Vol 17, No. 3, October 2004, Tribology of co-saputtered nanocomposite Au/MoS 2 solid lubricant films over a wide contact stress range. 3.Popov, V. L., Psakhie, S. G., Tribology International 39 (2006) pp , Physical nature and properties of dynamic surface layers in friction 4.Lince, J. R., Frantz, P. P., Tribology Letters, Vol 9, No. 3-4, 2000, Anistropic oxidation of MoS 2 crystallites studied by angle- resolved X-ray photoelectron spectroscopy 5.Hu, J. J., Zabinski, J. S., Tribology Letters, Vol. 18, No. 2, February 2005, Nanotribology and lubrication mechanisms of inorganic fullerene-like MoS 2 nanoparticles investigated using lateral force microscopy (LFM) 6.Tagawa, M. Muromoto, M., et al Tribology Letters, Vol. 18, No. 4, April 2005, Hyperthermal atomic oxygen interaction with MoS 2 lubricants and relevance to space environmental effects in low earth orbit – effects on friction coefficient and wear life 7.Hu. J. J., Bultman, J. E., Zabinski, J. S., Tribology Letters, Vol. 18, No. 1 January, 2006, Microstructure and lubrication mechanism of multilayered MoS 2 /Sb 2 O 3 thin films 8.Editorial Popov V. L. Tribology International 39, (2006), pp 369, Development of surface topography in friction processes 9.www.

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