Early stages of oxidation of uncoated and PVD SiO2 coated FeCrAl foils

The high temperature oxidation characteristics of uncoated and SiO₂ PVD-coated FeCrAl foils have been investigated when exposed to laboratory air at 1000 °C during 1, 2, 4, 8, 16, 32 and 60 min. The oxidized samples were characterized using SEM, EDS, AES and SIMS. The results show that the presence of a 100 nm thin SiO₂ PVD coating significantly reduces the oxidation rate of the FeCrAl foil during early stages of oxidation. The decreased oxidation rate displayed by the SiO₂ coated FeCrAl foil is the result of the SiO₂ coating acting as an initial diffusion barrier promoting the formation of a predominantly inward growing Al₂O₃ layer during oxidation. Additionally, by using EDS analysis together with AES and SIMS depth profiling it was shown that the total concentration of Si in the grown oxide scale decreased during oxidation.