Diamond-like carbon films synthesized under atmospheric pressure synthesized on PET substrates

Diamond-like carbon films were synthesized under atmospheric pressure (AP-DLC) and their gas barrier properties and hardness were measured. The AP-DLC films were uniformly obtained by RF-plasma CVD method at room temperature with a size of 450 mm(2). The growth rate increased as a function of C2H2 concentration and the average growth rate was around 12 mu m/min. The maximum deposition rate was similar to 1 mu m/s, which is approximately 2000 times larger than that by low-pressure plasma CVD of 1-2 mu m/h. The gas barrier properties of AP-DLC films, similar to 1 mu m thick. were 5-10 times larger than those of uncoated PET substrates. The microhardness of AP-DLC films was around 3 GPa, measured by the nano-indentation method. The issue lies in the removal of macro-particles of the films to improve the microlhardness and the surface roughness. In this paper. we report the physical properties of DLC films synthesized under atmospheric pressure by the radio-frequency CVD method. We also summarize a brief history of PET bottle coating by vacuum-DLC films, as well as that of the development of atmospheric pressure technology and related DLC films, focused on gas barrier properties and micro-hardness. (C) 2008 Elsevier B.V. All rights reserved.