Engineering the surface and interface of Parylene C coatings by low-temperature plasmas

There is a need for the development of environmentally benign processes by which to protect aluminum alloys from corrosion. Vacuum-deposited Parylene C conformal coating is a very good candidate to provide such protection due to its excellent bulk properties: its moisture barrier, high mechanical strength and thermal stability. However, its poor adhesion to most smooth or non-porous substrates has restricted its application. In this study, low-temperature plasma deposition and treatment has proved to be a powerful approach to engineer the surface and interface of Parylene C coatings. After applying a special plasma polymer coating, which acts as an inter-layer to provide good adhesion to the substrate as well as to the subsequent primer, an excellent adhesion of Parylene C coating to a smooth 7075-T6 aluminum alloy has been achieved. After the surface has been functionalized by plasma treatment, the naturally hydrophobic Parylene polymer became paintable with both solventborne and waterborne spray primers. (C) 2001 Elsevier Science B.V. All rights reserved.