NanoSIMS investigation of passive oxide films on high-Cr cast iron

摘要

The discrete depth characteristics of thin passive oxide films were investigated using high-resolution electron microprobe and nanoscale secondary ion mass spectrometry (NanoSIMS). A novel NanoSIMS method involving a Cs layer deposition before Cs~+ sputtering was employed for the first time to determine the elemental distribution at different sub-layers of a passive film. The film was formed in air on the surface of a multi-phase microstructure of high-chromium cast iron (HCCI). It was found that the film composition and thickness varied according to the underlying microstructure phase. Based on the micro-probe and NanoSIMS results, the influence of the HCCI passive film thickness and composition on the localized passivity breakdown has been proposed.