Historically, active materials (Navy Type III) used in compact, low cost Navy sonars, such as A-size sonobuoys have moderate d33 and low loss factor. Recent developments in lead-based textured ceramic with properties between those of conventional PZT ceramics and relaxor single crystals can improve the performance of these systems, but need to be manufactured at high volume and low cost. Most approaches for manufacturing these textured ceramics involve tape casting thin sheets containing a mixture of ceramic powder and binder with embedded template crystals that are cut to size, laminated, fired (to remove the binder) and then thermally post processed to convert the material to a pseudo-single crystal. Even with high levels of automation, the process is laborious since it requires the casting and stacking of hundreds of layers to produce material thick enough to incorporate into transducers with resonances low enough for most Navy applications. MSI Transducers Corp. (MSIs) innovative solution to reducing the time and cost to manufacture textured ceramic is to use Additive Manufacturing (AM) to form net-shape ceramic preforms (that include templates). These preforms are post processed, using methods in place at MSI, to produce textured ceramic with enhanced properties. In addition, we will replace simple textured ceramic plates or disks with structures that have higher performance, such a 3-3 composites and auxetic structures, to increase output, reduce the amount of textured material used and also decrease the weight of the transducer. Modeling has shown that these shapes can increase the charge coefficient (d33) as much as 3.9 times those of solid ceramic blocks and require 2/3 less material.
Benefit: At the end of the proposed program, MSI will have developed and demonstrated a process for Additive Manufacturing textured ceramic at less than two times the cost of conventional ceramic. These will be available for incorporation into low frequency, high power projector applications.
Keywords: tape casting, tape casting, PMN-PZT, textured ceramic, additive manufacturing
