The structure and adhesion of hydrogenated amorphous carbon (a-C:H) films synthesized on CoCrMo alloy by plasma immersion ion implantation and deposition at different flow ratios of acetylene to argon

Hydrogenated amorphous carbon (a-C:H) film is deposited on CoCrMo alloy by plasma immersion ion implantation and deposition (PIII-D) at different flow ratios of acetylene to argon (C2H2/Ar). The results show that Ar fraction in the C2H2–Ar gas mixture has an important effect on the structure and the adhesion of the a-C:H films. When Ar fraction in the C2H2–Ar gas mixture is less than 50%, the fabricated a-C:H film composition transfer from graphite-like to diamond-like which contains higher sp3 binding thanks to Ar ion bombardment, and the adhesion strength decreased with the increment of Ar fraction. But when Ar fraction in the C2H2–Ar gas mixture is beyond 50%, the fabricated film contains more sp2 bonding for thermally driven and exhibits higher adhesion strength with the increment of the Ar fraction.