Ultrasonic testing of artificial defects in alumina ceramic

This research tried to correlate the defect diameter and the ultrasonic signal reflected from the interface between an alumina matrix and artificial cylinder-like defects. Some fundamental acoustic and geometrical equations were used to determine the diameter from some known or pre-measured parameters. A final comparison between the real and predicted defect diameter was made to check out the accuracy of the model. The error of the size prediction of a solid defect was smaller than 65% in 10 MHz ultrasonic testing and even smaller than 15% when the defect type was a hole. The influence of the defect diameter on the prediction was dependent on the shrinkage of the specimens. We also found that the best density for ultrasonic testing was around 3.8 gm/cm(3). (C) 1997 Elsevier Science Limited and Techna S.r.l.