ICMCTF2006 Session F3-2: Nanotribology Instrumentation and Diagnostics

Monday, May 1, 2006 1:30 PM in Room Royal Palm 1-3

Monday Afternoon

Start	Invited?	Item
1:30 PM		F3-2-1 Conductive Atomic Force Microscopic (c-AFM) Studies of Au/MoS₂ Nanocomposite Films H.I. Kim, J.R. Lince (The Aerospace Corporation) Au/MoS₂ nanocomposite films are multifunctional coatings that are both lubricious and conductive. Hence, they could be useful for various electromechanical devices that require transmission of electrical signal across sliding interfaces, such as slip rings, switches and relays. Here, we have employed conductive atomic force microscopy (c-AFM) to investigate the mechanisms of material transfer and electrical conductivity of these films in the nano-scale. We have performed c-AFM on films with various Au-MoS₂ compositions to obtain nano-scale images of topography, friction, and conductivity. The topographical images showed that the particle sizes were relatively uniform, ranging from about 10 nm to 30 nm. The conductivity images initially showed distinct metallic (Au) and semi-conducting (MoS₂) domains that were relatively well dispersed, but repeated contact sliding over the same area caused gradual disappearance of the metallic domains and reduction of the overall friction, providing actual visualization of the lubrication mechanism. These results corroborate the contact-induced formation of an MoS₂ tribolayer on the surface observed by tribometry and Auger Nanoprobe analysis. In addition, a high-resolution AFM image was obtained in the worn area where MoS₂ layer has been formed. The resulting lattice structure revealed that this MoS₂ layer has a hexagonal structure with a lattice spacing of ~ 0.3 nm, providing a direct evidence of contact-induced crystallization and basal plane orientation.
1:50 PM		F3-2-2 Comprehensive Analyzing of Thin Film Nanoindentation Data via Internetportal - an in Principle Feasibility Study N. Schwarzer (Saxonian Institute of Surface Mechanics, Germany); M.C. Fuchs (Matrico Knowledge Engineering, Germany) Due to new analysing techniques applying the concept of the effectively shaped indenter a much more comprehensive analysing of nanoindentation data of thin films is possible [1]. Even in the case of very thin coatings well below 100nm thickness important physical mechanical parameters like Young's modulus, critical stresses for phase transition and Yield strength can be determined [2]. Theoretically, also fracture toughness (critical stresses for cracks of various fracture modes) and intrinsic stresses should in principle be determinable. However, as the mathematical apparatus for such analysing procedures is rather complex and the performance of the evaluation very cumbersome and difficult to learn, it seems reasonable to provide this type of calculation as a easy-to-use service on the internet. This contribution is about the principle feasibility of such a remote analysing service and the state of its realisation. ¹ N. Schwarzer, T. Chudoba, G. M. Pharr: "On the evaluation of stresses for coated materials during nanoindentation with sharp indenters", Surface and Coatings Technologies, in press, Corrected Proofs, doi:10.1016/j.surfcoat.2005.01.011 ² N. Schwarzer, T. Chudoba, F. Richter: "Investigation of ultra thin coatings using Nanoindentation", Surface and Coatings Technology, in press, accepted July 2005.