Application de la microscopie acoustique au contrôle non destructif des céramiques

New results in the application of ultrasonic microscopy to non destructive evaluation

¹ Laboratoires de Marcoussis, Centre de Recherches de la C.G.E.
² Laboratoire O.A.E., Université de Valenciennes

Abstract

Using an acoustic microscope working at a 100 MHz frequency, a great number of acoustic micrographs bas been taken from a series of ceramic (alumina and silicon carbide) samples. Defects have been detected and imaged up to a 5 mm depth with a spatial resolution somewhere between 50 and 100 µm.

The first part of this communication is devoted to the interpretation of the ultrasonic micrographs and their comparison with results obtained with alternative technique, like X-ray microfocus. Particularly using destructive controls for some runs, the mechanism of image contrast for high frequency focused ultrasound may be infered.

In the last part, special focused ultrasonic emitters are presented for particular uses, such as image processing. The principle, theoretical analysis and experimental results for these sources are reported.