Abstract
Surface properties of ion-irradiated organic-inorganic hybrid materials have been investigated. Disk samples of a nylon-clay hybrid (NCH) material were irradiated with 2 MeV Ar+to doses of 1×1014, 1×1015 and 1×1016 ions/cm2 and its tribological properties and water wettabilty were measured and compared with those of the nylon that was ion-irradiated under the same conditions. NCH is a nanometer-order hybrid which consists of a nylon matrix and silicate layers and is superior to nylon in heat resistance and strength.
Tribological properties were measured by pin-on-disk tests without lubricant using steel (SUJ2) balls as pins. Under ion irradiation to a dose of 1×1014 or 1×1015 ions/cm2, the wear resistance of the NCH decreased, becoming equivalent to that of unirradiated nylon, whereas the wear resistance of nylon was hardly changed by the same treatment. Ion irradiation to a dose of 1×1016 ions/cm2 improved wear resistance and decreased the coefficient of friction for both the NCH and nylon. In particular, in a 10-4Pa vacuum, the coefficient of friction for the NCH and nylon ion irradiated to a dose of 1×1016 ions/cm2 was extremely low (<0.1). The contact angle of the NCH with distilled water was increased from 68°to 80° by ion irradiation. Such a reduction in wettability was also observed for ion-irradiated nylon.
Fourier transform infrared spectroscopy, Raman spectroscopy and spectral-reflection measurement by laser plasma soft X-ray spectroscopy revealed that the structure of the NCH was destroyed by ion irradiation and that hard amorphous carbon formed on the surface of the NCH samples that were ion-irradiated at a dose of 1×1016ions/cm2. This suggests that these structural changes produced by ion irradiation determine the tribological properties of the NCH.
