Oxidation Resistance of Multilayered Cu-Cr Coatings Produced by Ion-Beam Assisted Deposition

摘要

Copper (Cu)-based alloys are of interest for high strength and high thermal conductivity applications in hypersonic vehicles at elevated temperatures. However, their usage at high temperatures is usually limited by severe oxidation attack. The use of protective coatings offers an avenue to limit inward migration of oxygen ions and extend the useful life of the Cu-alloys. In this investigation, multilayered Cu-Cr coatings with Cr contents of 10-25 % (all compositions are in wt% unless stated otherwise) were produced by a vacuum-based ion-beam assisted deposition (IBAD) technique. The coating microstructure was characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Oxidation behavior of the coatings was evaluated after exposure to air at 650℃. At low Cr content of 10%, the oxidation rates were controlled by outward diffusion of copper ions to form external oxides. For higher Cr contents ( > 15%), a combination Cu-oxides and an underlying Cr-rich oxide was formed on the coating surface and acts as a barrier for inward oxygen permeation.