Effect of deposition pressure on the properties of DLC coatings deposited by bipolar-type PBII&D

In the present study, the effect of deposition pressure on the deposition rate and various properties of diamond-like carbon (DLC) coatings were investigated. The DLC coatings were deposited on Si substrates using a bipolar-type plasma-based ion implantation and deposition plasma based ion implantation and deposition (PBIID) technique. The toluene was used as a source gas and the deposition pressure ranged from 0.03 to 2.0 Pa. The deposition rate of the DLC coatings increases about 12 times as the deposition pressure is changed from 0.03 to 2.0 Pa. Also, the surface roughness increases with increasing deposition pressure due to high deposition rate. The hardness and elastic modulus decrease when the deposition pressure exceed 0.7 Pa due to the remarkable growth of graphitic islands. The corrosion protection performance of the DLC coating deposited at 2.0 Pa is superior to that of the DLC coating deposited at 0.2 Pa for the same deposition time of 1 h. The high deposition pressure for the DLC coating is effective in improvement of corrosion protection properties. Copyright (c) 2008 John Wiley & Sons, Ltd.