AVS 49th International Symposium
    Thin Films Tuesday Sessions
       Session TF-TuM

Paper TF-TuM7
Pulsed Laser Ablated MoS@sub 2@-Al Films Characterized for Friction and Wear in Humid Conditions

Tuesday, November 5, 2002, 10:20 am, Room C-101

Session: Mechanical Properties of Thin Films
Presenter: J.J. Nainaparampil, AFRL/MLBT
Authors: J.J. Nainaparampil, AFRL/MLBT
A.R. Phani, University of New Hampshire
J.E. Kraznowski, University of New Hampshire
J.S. Zabinski, AFRL/MLBT
Correspondent: Click to Email
Molybdenum disulphide films are well known solid lubes in dry environmental conditions. However, even a slightest increase in humidity can adversely affect the performance of these films. Different authors tried various additives to strengthen the system and to change microstructure in such a way that wear life could be increased even in dry conditions compared to pure MoS@sub2@ films.@footnote 1,2,3@ Some of those work addressed the problem of humidity by adding metals and oxides of metals. However, the complete explanation of the phenomenon has not been discovered and an approach that focuses on both tribochemical reactions and microstructure is required. The work reported here deals with addition of Al metal as an additive to resist the degradation of MoS@sub2@ coatings in humid conditions. Since aluminum shows very high affinity for (OH) radicals to form Al(OH)@sub3@, it is suggested that aluminum likely reacts with H@sub2@O in humid conditions. Al(OH)@sub3@ is relatively soft and may enhance lubrication and reduce friction and wear. The microstructure of Al-containing films and their mechanical properties may also contribute to tribological performance. Films for this study were prepared by pulsed laser ablation of MoS@sub2@ targets along with magnetron sputtering of aluminum to form aluminum alloyed MoS@sub2@ films. Data from pin on disc tribotests showed long wear life and a friction coefficient between 0.1 and 0.2 even at high relative humidity (i.e., 50%). The microstructure and stoichiometry of these films are under further study to control mechanical properties such as hardness, adhesion and toughness. Micro-Raman and high-resolution SEM pictures of wear tracks will be presented. @FootnoteText@ @footnote 1@Stupp B. C. Thin Solid Films, 84, 1981, 257 @footnote 2@J. S. Zabinski, M. S. Donley, and S. D. Walck, Tribol. Trans. 38(4) 1995, 894 @footnote 3@E. Pfluger, J. D. Holbery, A. Savan, Y. Gerbig, Q. Luo, D. B. Lewis, W. D. Munz, Proceedings of II World Tribology Congress, Vienna, 2001, 313.