Development of Ultrasonic Tests for Super Ceramics

Abstract

Critical flaw sizes in ceramic turbine parts are very small, especially for dynamic applications. Detection of these small ( < 30 pm) internal flaws are almost exclusively in the realm of ultrasonics, wherein 30 to 100 MHz test frequencies are required. Satisfactory transducers for this purpose are not available from commercial suppliers. These devices are now being developed and will be discussed together with problems of signal strength, focussing, penetration and defect signal characterization in ceramics containing both real and artificial defects.