Modification of interfacial characteristics between diamondlike carbon films and substrates by using ion bombardment

Ion bombardment has been used to modify the interfacial characteristics of diamondlike films produced by using a pulsed arc discharge deposition method. The films were deposited onto annealed unalloyed carbon steel substrates. Two different structures were studied. In the first configuration a 40 nm thick film was deposited directly onto a steel substrate. In the other case a buffer layer of SiC with a thickness of 20 nm was first deposited, followed by a deposition of a 40 nm thick diamondlike film. Both kinds of samples were exposed to ion bombardment of ¹³C ions at an energy of 50 keV with the fluences of 10¹⁵ and 5 × 10¹⁵ ions/cm². Ion bombardment did not result in any changes in the adhesion of the diamondlike film without the buffer layer as determined by using a pull test. However, ion bombardment up to 5 × 10¹⁵ ions/cm² of the sample with the SiC buffer layer improved the adhesion beyond the testing capability of the pull tester. The results are discussed in terms of the thermodynamical properties and computer simulations of the atomic movement at the coating/substrate interface. Preliminary tests on the effect of a high fluence of 10¹⁷ ions/cm² on the adhesion of a diamondlike film on AISI 316 stainless steel were also performed and the results, which are complemented with secondary ion mass spectroscopy (SIMS) measurements, are presented.