Surface Acoustic Wave Studies of Surface Cracks in Ceramics

A 10 to 100 MHz surface acoustic wave (SAW) system with computer controlled data acquisition and analysis was used to study the detection and characterization of surface cracks in ceramics. Surface acoustic waves were generated by placing a focused transducer at a critical angle with respect to the test specimen. The scattering of surface waves into water by the surface cracks was detected, analysed in the time domain and correlated with the size and the shape of the cracks. At 100 MHz, the SAW technique can detect cracks as small as 25 µm deep on polished ceramics