Enhanced Corrosion Protection of Copper in Salt Environments with Nanolaminate Ceramic Coatings Deposited by Atomic Layer Deposition

Abstract

Thin metal oxide films were deposited by atomic layer deposition (ALD) for corrosion protection of copper surfaces. ALD films were grown on the inner surface region of 0.125” inner diameter copper tubing and on monitor test coupons. The ALD materials tested included single layers of alumina (Al2O3), titania (TiO2), and hafnia (HfO2), and nanolaminate combinations of these materials up to 50nm in coating thickness. Electrochemical impedance spectroscopy was performed on Cu coupons over a 3-day period in 0.1 M NaCl to assess coating stability over time. HfO2 and TiO2 were found to be stable in oxygenated NaCl, whereas Al2O3 coatings show significant degradation. Coated and uncoated copper tubes were exposed to dynamic flow environments with turbulent flowing salt solutions to simulate the operating environment of cooling channels found in RF devices. HfO2-coated tubes showed little oxidation after an 8-week exposure period compared to uncoated tubing.