PROGRESS IN THE CHARACTERIZATION OF NANOPHASE DIAMOND FILMS UNIQUELY PRODUCED BY A LASER-PLASMA DISCHARGE SOURCE

Films of nanophase diamond can be deposited at room temperature with a laser plasma discharge source of multiply charged carbon ions, without the use of any catalyst in the growth mechanism. The beam from a pulsed Nd:YAG laser is focused on graphite at intensities in excess of 10(11) W cm-2 and the resulting plasma ejects carbon ions carrying energies of about 1 keV through a discharge space to the substrates to be coated. The high energies of condensation produce interfacial layers between the film and substrate materials, which provide levels of adhesion which can support the protection of substrates subjected to harsh environmental conditions. In this paper, recent advances in the characterization of nanophase diamond films arc given. Emphasis has been placed on studies of the bonding and properties realized in one example; i.e. the deposition of nanophase diamond on stainless steel. Measurements with Rutherford backscattering spectrometry showed that the diamond coatings deposited from laser plasmas were bonded to the stainless steel substrates through interfacial layers with significant thicknesses. The resistance to wear was estimated with a modified sandblaster and it was shown that a coating of only 2 mum of nanophase diamond can increase the lifetime of the sample by a factor of better than 36. The results of other mechanical measurements, such as those obtained by friction tests, are also given.