Fine-scale, large area piezoelectric fiber/polymer composites for transducer applications

Several methods of forming piezoelectric ceramic/polymer composites for possible transducer applications were demonstrated. These methods include the replication technique, tape casting, honeycomb dicing, and ceramic fiber weaving. In the replication technique, activated carbon fibers or fabrics are soaked in a PZT precursor solution and then arranged into desired structures. The soaked structures are dried and fired, yielding a ceramic relic with the same structure. Three types of structures were developed: shells, combs, and weaves. The highest d/sub 33/ of 290 pC/N was found in the shell structure, and the d/sub h/g/sub h/ of both the shell and weave designs were about 5000/spl times/10/sup -15/ m/sup 2//N. The results of scaling-up the weave structure from 2.5/spl times/2.5 cm/sup 2/ to 10/spl times/10 cm/sup 2/ are reported. The feasibility of producing larger area samples using relic tile arrays is also discussed. In the tape casting technique, 2-2 and 1-3 structures were formed using thin PZT tapes. The tapes are stacked, with spacers separating the layers, and the stack is embedded in polymer. Dicing the stack results in a composite with 1-3 connectivity. The thin tape technique can be used to develop composites with ceramic or polymer volume gradients and multifunctional ceramics. Dicing of PZT honeycombs yields 1-3 composites with uniquely shaped rods. Shapes included "+"s, "T"s, and "L"s. In the ceramic fiber weaving technique, green PZT fibers are woven through a PZT honeycomb support structure. The structure is fired to sinter the PZT fibers, and embedded with polymer to yield 1-3 composites. All 1-3 composites showed high and uniform piezoelectric coefficients across the electroded area.