Ultrasonic characterization of density and elastic properties in Bi-2212 powder compacts

This paper addresses the development and application of advanced sensing based on emerging nondestructive evaluation techniques, such as ultrasound, resonant frequency, x-ray, etc., for characterizing product quality at various stages of high temperature superconducting (HTS) conductor manufacturing. These techniques provide valuable information on the relationships between process variables and product properties, and enable new/emerging manufacturing process optimization. Such techniques are being explored for the characterization of critical product parameters at various stages of Bi-2212 powde-intube process. In addition, these techniques, when implemented in real-time, promise significant benefits for sensing and process control of HTS conductor processing. Specifically, this paper discusses the development of ultrasonic techniques for characterizing density and elastic properties in Bi-2212 powder compacts. Ultrasonic longitudinal and shear wave velocities in these materials were measured at 2.25 MHz. Ultrasonic velocity is a strong function of density (hence porosity) and provides a potential means of measurement of this quantity. Also presented are ultrasonic measurement of elastic properties of Bi-2212 compacts.