Diamond-like carbon coated on polyethylene terephthalate by Thermionic Vacuum Arc

Diamond-like carbon (DLC) coatings were deposited on transparent polyethylene terephthalate (PET) using a thermionic vacuum arc (TVA) method. The TVA method parameters used to produce DLC coating and the volt-ampere characteristic during the plasma ignition were determined with 22 A of filament current. The crystal orientations and surface morphology of the deposited DLC thin films were investigated using X-ray diffractometer and atomic force microscopy. Reflectance and refractive indices of DLC-coated PET were analyzed by interferometry. According to experimental measurement, DLC-coated thin film was polycrystalline with (1 1 1) and (1 1 0) preferred orientations. Refractive indices were approximately 2.60 in the visible range. DLC-coated PET reflection is close to the PET substrate in the infrared region. According to Fresnel equation, the DLC-coated PET reflection decreased from 19.25% to 10% at 632 nm due to local coating agglomeration. Surface hardness increased to from 2.77 to 10 GPa with DLC coating.