Improvement of adhesion strength of amorphous carbon films on tungsten ion implanted 321 stainless steel substrate

Amorphous carbon (a-C) films have many potential applications due to their good mechanical properties. However, poor adhesion on substrates such as tool steels limits its applications. In the present work, a-C films were deposited on W-implanted (20 kV, 3 × 10¹⁷ ions-cm^{- 2}) steel substrates by means of plasma immersion ion implantation and deposition (PIII&D). Compared to the films deposited on untreated steel substrates, the films deposited on the W-implanted steel substrates exhibit improved hardness, surface morphology, and adhesion strength. The modified layer with graded mechanical properties not only provides a structural continuity from the substrate to the film but also acts as the interlayer to mitigate stress concentration under applied loads.