Al2O3 coating with a Ni-based buffer layer: Preparation, characterization and electrical insulating properties

Al2O3 coatings, with a Ni-based buffer layer (Ni or NiAl), were deposited on a Cu substrate by electron beam evaporation (EBE). The Al2O3 coatings were amorphous of good stoichiometry and their surface was undulated and continuous. The Ni-based buffer layer played a key role on improving the adhesion of the Al2O3 coatings to the substrate. The diffusion of Cu from the substrate into the Al2O3 coating at high temperature was suppressed by the buffer layer. Excellent resistivity (1015 Ω cm) and high breakdown voltage (110 kV/mm) have been obtained.