Characterization of Thin Oxide using FIB-SIMS and FIB-TEM Techniques

Abstract

The use of SIMS for the characterization and study of biomaterial surfaces is fast gaining popularity in the development of bio-functional and bioactive tissue compatible interfaces. The presence of TiO2oxide in metallic Ti implants and its ability to promote bioactivity is still unclear. FIB-SIMS (Focused Ion Beam-Secondary Ion Mass Spectrometry) and FIB-TEM (FIB-Transmission Electron Microscopy) techniques represent powerful tools for characterizing the oxide layer. This paper investigates the oxygen transport mechanism of thermal barrier coating systems applied on nickel-base superalloy turbine blades. In this study, a two-stage oxidation experiment is used.18O2is used as a tracer during the second stage oxidation on previously oxidized Ni-base superalloys with a layer of bond coat material. The aluminium oxide grown in16O2during the first stage oxidation serves as a background oxide. Mass spectra collected by FIB-SIMS reveal the counter mass transportation by inward diffusion of oxygen and outward diffusion of aluminium. New oxide formation during the second stage oxidation under an18O2enriched environment is observed at both the gas/oxide interface as well as oxide/superalloy interface. Transmission Electron Microscopy (TEM) can be used to identify the very fine phases developed in both the inter-diffusion zone as well as the thermally grown oxide layer. The use of Focused Ion Beam (FIB) technique allows for selective nano-machining of areas of interest for the production of TEM samples. FIB-SIMS and TEM are carried out to determine the specific phase transformations occurring in the TBC system.