Abstract
Young's modulus of functionally gradient Al2O3 ceramics, which was formed by centrifugal casting and has gradient of the elastic properties along a partiarlar direction on the surface, is estimated by velocity measurement of the leaky Rayleigh and longitudinal waves. Those velocities were measured every 1mm with a line focused PVDF transducer,, of which central frequency, focal length and width are 36MHz, 5mm and 8mm. Thus measured Young's modulus varies from 370GPa (Al2O3 rich side) to 200GPa (Ni rich side).