STIM tomography: A potential tool for the non-destructive characterisationof SiC microcomposite materials

Despite the fact that ion micro-tomography techniques were initiated severa l years ago, useful applications are still rare in material sciences. This work is a preliminary study on the non-destructive characterisation of a th in BN interphase in a ceramic matrix composite material by scanning transmi ssion ion microscopy (STIM) tomography. The technique, initially developed at CENBG for applications in the biomedical field, was used here to investi gate several model composites as processed and after oxidation tests at hig h temperature. The data reduction codes, based on analytic reconstruction methods, made it possible to determine the spatial extension of the BN interphase in transv ersal planes at different positions along the microcomposites (25 mum in di ameter). This measurement was performed taking advantage of the density con trast between SiC and BN even for a layer thickness down to 3 mum. A first attempt was also made to separate the initial BN interphase from the B2O3 l ayer formed on its surface during oxidation, (C) 2001 Elsevier Science B.V. All rights reserved.