HIGH-ENERGY (MEV) ION-BEAM MODIFICATIONS OF SPUTTERED MOS2 COATINGS ON CERAMICS

DC magnetron sputtered-MoS2 films of thicknesses between 500angstrom and 7500angstrom were deposited on NaCl, Si, sapphire, Si3N4 and ZrO2 substrates, and were subsequently ion irradiated by a 5 x 10(15) cm-2 dose of 2MeV Ag+ ions. Transmission electron microscopy (TEM), Rutherford backscattering (RBS) and Auger Electron Spectroscopy (AES) were utilized to study the microstructural and compositional changes of the film due to irradiation. The friction coefficient and sliding life were determined by ball-on-disc tests under both inert and humid conditions. Both as-deposited and ion-irradiated films were found to be amorphous, having a stoichiometry of MoS1.8. A low friction coefficient in the range of 0.03 to 0.04 was measured for both as-deposited and ion irradiated films. However, the sliding life of Ag+ ion-irradiated film was found to increase ten fold to thousand-fold compared to as-sputtered films on all the ceramic surfaces studied The improvement in wear life was correlated with a significant improvement in adhesion of the film with the substrate and a small increase in the density of the ion irradiated film.