High energy (MeV) ion beam modifications of sputtered MoS2 coatings on sapphire

The present article reports on the results of our investigations of high-energy (MeV) ion irradiation on the microstructural and tribological properties of dc magnetron sputtered MoS2 films. Films of thicknesses 500-7500 A were deposited on NaCl, Si and sapphire substrates and subsequently ion irradiated by 2 MeV Ag+ ions at a dose of 5x1015 cm-2. Scanning and transmission electron microscopy. Rutherford backscattering and X-ray diffraction techniques were utilized to study the structural, morphological and compositional changes of the film due to ion irradiation. The friction coefficient and sliding life were determined by pin-on-disc tests. 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 0.03-0.04 was measured for both as-deposited and ion-irradiated films. However, the sliding life of ion-irradiated film was found to increase more than tenfold compared to as-deposited films indicating improved bonding at the interface. (orig.)