Evaluation of the anti-fouling properties of nm thick atmospheric plasma deposited coatings

Both organic and inorganic fouling are significant problems for stainless steel surfaces used in industrial applications as diverse as shipping and paper making. The objective of this study is to evaluate the anti-fouling properties of a range of fluoropolymer, fluorinated and non-fluorinated siloxane coatings on stainless steel substrates. These nm thick coatings were deposited using the atmospheric plasma jet system called PlasmaStream™. The surface properties of the plasma polymerised coatings were examined using optical profilometry, SEM–EDX, ellipsometry, contact angle measurement and FTIR. Accelerated wear testing of the coated heat exchangers indicated that coating durability was a significant issue for the nanometre thick coatings investigated. A crystallization fouling study was carried out using a laboratory scale heat exchanger test apparatus. In this the heated steel surface was in contact with flowing fluid containing CaCO3 particles. The coated steel exhibited both a delay before fouling was initiated and in addition a decrease in the fouling rate. A lubricant oil fouling study was also carried out involving a comparison between both coated and uncoated stainless steel separator discs over a 30 day period, in the engine of a passenger ferry. A significant reduction in the level of oil fouling was observed for the fluorosiloxane and fluoropolymer coated separator discs compared with the uncoated discs.