1999 Volume 48 Issue 7 Pages 445-450
Diamond-like carbon (DLC) films were coated on SUS 304 stainless steel using an ionization deposition method and the area of defects in the films was determined by the critical passivation current density (CPCD) method. The area of pinhole defects in the DLC films (Ri) was evaluated as functions of applied negative bias voltage and the film thickness. The value of Ri for the films thinner than 100nm was not influenced by the bias voltage. On the other hand, the value of Ri for the films thicker than 100nm decreased with increasing bias voltage. For each bias voltage, the density and size of the defects in the DLC films decreased with increasing their thickness. In particular, the Ri-value of the film of 550nm thickness prepared at the bias voltage of -2000V was approximately 0.01%, being lower by a factor of 100 than that of TiN films with similar thickness which was prepared by hollow cathode discharge technique. Therefore, it is concluded from the present work that the protection ability has been improved remarkably by the DLC films (below 600nm) prepared by the ionization deposition method.
