Materials characterization and effect of purity and ion implantation on the friction and wear of sublimed fullerene film
- PDF / 9,775,656 Bytes
- 16 Pages / 576 x 792 pts Page_size
- 38 Downloads / 174 Views
C. Capp and J. V. Coe Department of Chemistry, The Ohio State University, Columbus, Ohio 43210-1107 (Received 18 April 1994; accepted 28 July 1994)
In previous studies, sublimed C60-rich fullerene films on silicon, when slid against a 52100 steel ball under dry conditions, have exhibited low coefficient of friction (—0.12). Films with different purities can be produced by sublimation at different substrate temperatures. In this paper, effects of purity of fullerene films and ion implantation of the films with Ar ions on the friction and wear properties of sublimed fullerene films are reported. C6o-rich films (called here films with high purity) exhibit low macroscale friction. An increased amount of C70 and impurities in the fullerene film determined using Raman and Fourier transform infrared (FTIR), increases its coefficient of friction. Microscale friction measurements using friction force microscopy also exhibited similar trends. Low coefficient of friction of sublimed C6o-rich films on silicon is probably due to the formation of a tenacious transfer film of C60 molecules on the mating 52100 steel ball surface. Based on scanning tunneling microscopy (STM), transmission electron microscopy (TEM), and high resolution TEM (HRTEM), we found that fullerene films primarily consisted of C6o molecules in a fee lattice structure. Nanoindenter was used to measure hardness and elastic modulus of the as-deposited films. Ion-implantation with 1 X 1016 Ar+ cm"2 reduced macroscale friction down to about 0.10 from 0.12 with an increase in wear life by a factor of 4; however, doses of 5 X 1016 ions cm"2 gave three times higher friction and poorer wear life; higher doses disintegrated the C6o molecules. Based on STM, TEM, Raman, FTIR, and laser desorption Fourier-transform ion cyclotron resonance mass spectrometer (LD/FT/ICR) studies, we found that the ion implantation with a dose of 1 X 1016 Ar+ cm"2 resulted in smoothening of the fullerene film surface probably by compacting clusters, but without disintegrating the Cg0 molecules. However, a high dose of 5 X 1016 Ar+ cm"2 damaged the C6o molecules, converting it to an amorphous carbon. Nanoindentation studies show that ion implantation with a dose of 1 X 1016 Ar+ cm"2 resulted in an increase in the hardness from about 1.2 to 4.0 GPa and in elastic modulus from about 70 to 75 GPa and modified the elastic-plastic deformation behavior.
I. INTRODUCTION Recent studies on the tribological properties of fullerenes have shown that sublimed C6o-rich films exhibit low friction and wear comparable to that of graphite and MoS 2 films.1"3 Fullerenes behave very similar to graphite and MoS 2 because of their common bonding features. At room temperature, fullerene solids are characterized by strong intramolecular and weak intermolecular (van der Waals bonding between the C 60 molecules) bonding.4"7 Because of weak van der Waals J. Mater. Res., Vol. 9, No. 11, Nov 1994 http://journals.cambridge.org
Downloaded: 11 Mar 2015
forces between the C6o molecules, C6o molecules and clusters may deta
Data Loading...
