Fabrication of Curved Ceramic / Polymer Composite Transducers for Ultrasonic Imaging Applications by Fused Deposition of Ceramics

Fused Deposition of Ceramics (FDC), developed at Rutgers University, is a Solid Freeform Fabrication (SFF) technique where a three-dimensional green ceramic object is built layer by layer, starting from a Computer Aided Design (CAD) file of the object. This technique was used to build novel piezoelectric ultrasonic transducers for medical imaging applications. Curved ceramic skeletons for 2-2 (parallel ceramic / epoxy plates) composite transducers were built by FDC. The design's curvature can be tailored in the CAD file. Therefore, the final composite requires very little machining. In the FDC-built green parts, the ceramic plates were 500 um thick and the spacing between the plates was 1270 um. The FDC green samples were subjected to a slow binder burnout cycle at 550°C for 4 hours, using a heating rate of 8°C per hour, then sintered at 1285°C for 1 hour. Physical characterization of the samples revealed that 95% ofthe theoretical density was achieved. The ceramic plates shrunk 20% in height as well as in width. The shrinkage was of only 16% in the direction parallel to the plates. Optical microscopy and SEM were performed on green and sintered samples. The results of these characterizations are reported in this paper as well as the electromechanical properties of the final composites and of FDC bulk samples.