Magnetic-field enhanced plasma immersion ion implantation and deposition (PIII&D) of diamond-like carbon films inside tubes

The present work deals with Diamond-like Carbon (DLC) films deposition inside metallic tubes using magnetic field generated in a PIII&D system. Firstly, the features of plasma discharges with the magnetic field application were studied using different feeding gases as nitrogen, methane and acetylene. The experimental results demonstrate that a stable hollow cathode discharge can be established inside the tubes as the magnetic field is applied. The discharge breakdown is strongly affected by the presence of the magnetic field during the treatment. Secondly, PIII&D experiments regarding DLC films deposition inside the inner surface of the tubes are also described and those ones enhanced by the applied magnetic field are emphasized. The sample tubes used in both experimental stages are of austenitic stainless steel with 150 mm in length and different diameters: 110 mm, 40 mm and 20 mm. For the case of DLC deposition, polished steel samples were fixed in the bottom of the inner tube wall for subsequent analysis of the coatings. The as-coated DLC samples surface were analyzed by Raman Spectroscopy, X-ray Photoelectron Spectroscopy (XPS), Scanning Electron Microscopy (SEM), optical profilometry and also pin-on-disk tests. The properties of the obtained DLC films are correlated to the magnetic field used during the PIII&D process. In this work, the optimal range of magnetic field intensity is shown for depositing DLC films with acceptable adhesion strength on the inner surface of steel tubes.