AVS 51st International Symposium
    Plasma Science and Technology Monday Sessions
       Session PS2-MoA

Paper PS2-MoA8
RF Plasma Deposition of Thin SiO@subx@ Films onto Aluminium Alloy: XPS and Contact Angle Measurements Studies

Monday, November 15, 2004, 4:20 pm, Room 213B

Session: Emerging Plasma Applications
Presenter: A. Azioune, Lise Namur, Belgium
Authors: A. Azioune, Lise Namur, Belgium
M. Marcozzi, Lise Namur, Belgium
V. Revello, Lise Namur, Belgium
J.-J. Pireaux, Lise Namur, Belgium
Correspondent: Click to Email
Protection of (metallic) substrates via paints is widely used in many sectors including the aerospace industry. The efficiency of the process depends on the durability of the paints and on the properties of the interface between the organic layer and the surface metal oxides; thus, the pre-treatment of the aluminium alloy prior painting is a very important step to long term - performance for this technology. However, most of the pre-treatments used now on the aluminium present environmental drawbacks as they are based on solvents and chromates. An alternative efficient and ecologically cleaner method is the plasma technology. In the present work, the aluminium substrates (Al-clad 2024) were cleaned by RF (13.56 MHz) plasma, from a mixture of oxygen and argon gases. It is observed that the carbon contamination is completely removed using Ar plasma. Thin SiO@sub x@ films have been deposited by plasma a mixture of hexamethyldisiloxane (HMDSO) and oxygen (20 W, 5 min). In the absence of oxygen, a thick (> 10 nm) and superhydrophobic (@theta@ @>=@ 100°) film characteristic of PDMS properties is formed; polysiloxane-like thin ( < 10 nm) films (SiO@sub x@) are obtained with the introduction of oxygen (20, 50 and 80%). Both XPS and contact angle measurements confirmed both the composition and the structure of these films. More importantly, contact angle measurements using different liquids and interpreted with the van Oss Good Chaudhury theory, allowed to determine the surface free energy of the deposited films: the calculated surface tensions (@gamma@ @subs@, @gamma@ @subs@ @superd@, @gamma@@subs@ @super+@ and @gamma@@subs@ @super-@) of the film formed from HMDSO/O@sub 2@: 50/50 are in excellent agreement with those of reference silicium oxide substrates. @FootnoteText@ This work is supported by Walloon Region (RW n° 021/5208) in the framework of a collective reasearch project "ECOPO" in collaboration with Université de Mons-Hainaut and Coating Research Institute.