THIN FOIL PREPARATION OF METAL PARTICLES IN BRITTLE CERAMIC MATRICES

Thin foil preparation for metal particles in brittle ceramic matrices is particularly difficult, due to differential thinning of the compone nt materials. This paper considers the preparation of thin foils of st ony meteorites. Stony meteorites have a composite nature consisting of small metal particles (< 200 mu m) embedded in an inherently brittle silicate matrix. Specimens of this type are difficult to prepare as th in foils because the area of interest is limited to specific regions w ithin the metal particles. The problems of thin foil preparation of me tal particles in the stony meteorites were overcome by developing a te chnique involving electrochemical polishing prior to ion beam thinning . The metal particles were first separated from the silicate matrix an d then embedded in Epo-Tek H20E silver epoxy. This specific epoxy was selected for its good electron conductivity which allowed the specimen to be thinned by the electrochemical polishing technique. Specimens p repared by this technique have permitted the direct observation and ch aracterization of the metallic phases in stony meteorites. (C) 1996 Wi ley-Liss, Inc.