Enhancement of Adhesive Strength of DLC Film by Plasma-Based Ion Implantation

Abstract

The thick diamond-like carbon (DLC) film of good-adhesion was prepared on a stainless steel (SUS304) substrate by a hybrid process of plasma-based ion implantation and deposition using hydrocarbon gases such as methane, acetylene, and toluene. In this process, a high repetition pulsed plasma was produced by RF pulse (13.56 MHz) with the duration of 50 µs and the repetition rate of 0.5 - 1 kHz. Besides, the plasma ions were implanted to the substrate by a negative pulsed voltage of -20 kV and the pulse duration of 5 µs. Ion implantation served to produce a graded interface of carbon component in the boundary region of DLC film and substrate, and also to reduce the residual stress to several MPa, enhancing the adhesive strength of DLC film. Furthermore, the adhesive strength of DLC film was increased above the epoxy resin strength (about 65 MPa) by implantation of mixed Si and C ions.