Crystallization of Molybdenum Disulfide Films Deposited by Pulsed Laser Ablation

  • PDF / 383,148 Bytes
  • 6 Pages / 420.48 x 639 pts Page_size
  • 35 Downloads / 337 Views

DOWNLOAD

REPORT


CRYSTALLIZATION OF MOLYBDENUM DISULFIDE FILMS DEPOSITED BY PULSED LASER ABLATION J.S. Zabinski*, M.S. Donley*, P.J. John,** V.J. Dyhouse**, A.J. Safriet, ** and N.T. McDevitt*** * WRDC/MLBT, Materials Laboratory, Wright-Patterson AFB, OH 45433-6533 University of Dayton Research Institute, Dayton, OH 45469-0168 *** RAMSPEC Research, 4399 E. Mohave Dr., Dayton, OH 45431 ABSTRACT" Pulsed laser &blation (PLA) is an emerging technology that provides a mechanism to deposit lubricious films and to tailor film properties by the appropriate choice of substrate materials, deposition parameters and post deposition treatments. The properties of MoS2 films deposited by PLA are evaluated as a function of: (1) substrate material, (2) duration of post deposition annealing treatments using 248 nm laser radiation and (3) substrate temperature during deposition. The chemistry and crystal structure of the different films are determined using small angle 2X.-ray diffraction (XRD), Raman spectroscopy, X-ray p.hotoelectron sLpectroscopy (XPS) and The tribological properties of the &utherford bDackscattering spectroscopy (RBS). films are then evaluated as a function of their chemistry and crystal structure. INTRODUCT'ION Molybdenite has been effectively applied to wear surfaces by mechanical burnishing, binding agents and lubricant compacts (1]. However, lubrication of space mechanisms and precision components necessitated greater control over film thickness than available from the above techniques. In addition, component operating temperatures may be limited by available binding agents. These deficiences were addressed by application of %putter deposition (SD) techniques to lubricant coatings technology which permitted reliable control of film thickness and eliminated temperature limitations imposed by binding agents [2]. The chemical and physical properties of SD films have been investigated and correlated to their friction and wear properties [3-9]. While sputter deposited lubricant coatings are technologically important, they possess several characteristics that limit their effectiveness. SD films are frequently contaminated by background gases in the deposition chamber (i.e., H20, 02, etc.) [8-10]. Oxygen impurities may not be detrimental to film integrity for room temperature applications but recent studies suggest that they may accelerate lubricant decomposition at elevated temperatures (11]. SD films typically have a platelike, porous morphology with the MoS2 basal planes perpendicular to the substrate surface thereby exposing reactive edge planes to the environment and increasing their reactivity towards oxidants [12-15]. Some of the deficiencies discussed above have been addressed in recent studies of SD operating conditions [16] and of ion beam a.ssisted sputter deposition (IBAD) [17-19]. In both cases, the formation of dense, "basal" oriented MoS2 films was reported. PLA is an attractive alternate technique for the deposition of lubricant materials that does not rely on sputtering processes. The laser technique permits the dep

Data Loading...