Investigation of DLC synthesized by plasma immersion ion implantation and deposition

We investigated the mechanical, chemical and structural properties of amorphous diamond-like carbon (a-C:H) thin films prepared by a special plasma immersion ion implantation and deposition (PIII and D) process suited to these requirements. The resulting diamond-like carbon (DLC) films were characterized tribologically by nanoindent hardness measurements, oscillating ball-on-disc friction and wear tests as well as impact and scratch adhesion tests. Moreover, porosity tests with ferricyanide reagent and corrosion test with various acids and bases were carried out. It was found that the hardness can be adjusted between 5 and 20 GPa depending on the process parameters. Raman spectroscopy was employed to study the structural characteristics of the DLC layers. The sp3 content of the films could also indirectly be deduced from Raman results and was found to be 30% to 50%. The amount of residual hydrogen, 50 to 25 at.%, was determined using elastic recoil detection analysis (ERDA) and correlated to the mechanical properties. Dependencies of the properties on the PIII and D process parameters like pulse frequency, pulse voltage and ion dose are discussed.