Kröning, M.M.KröningSchneider, R.R.SchneiderNetzelmann, U.U.Netzelmann2022-03-092022-03-091996https://publica.fraunhofer.de/handle/publica/326019Time-of-flight measurements using ultrasound at 2 MHz and microwaves at 75-100 GHz were performed on samples of green state alumina. Spatially resolved measurements showed an inverse correlation of time-of-flight measured by ultrasound and microwaves. The findings can be explained by a lower compaction density in the center of the sample cylinders. A model assuming small spherical pores does not explain the experiment completely. An uniaxial anisotropy of longitudinal sound velocity was foundenaluminaaluminiumAnisotropieanisotropydensity gradientgreen ceramicGrünkeramikmicrowaveMikrowellenondestructive testingsynthetic pulsetime of flight measurementUltraschallultrasoundzerstörungsfreie Prüfung620658670conference paper