Fused Deposition of Ceramics (FDC) and Metals (FDMet) are SFF techniques, based on commercial FDM(TM) technology, for fabrication of ceramic and metal components. The FD processes use feed material in the form of filaments which require certain physical and mechanical.. properties. FDC and FDMet processes employ filaments formed from ceramic or metal powders mixed with thermoplastic polymers. The thermoplastic polymers act as binder during the FDC and FDMet processing in forming a green part. Development of green ceramic or metal filaments for FDC or FDMet processing involves three critical steps : selection of an appropriate binder chemistry, appropriate mixing, procedures and filament fabrication techniques. This study describes the properties required for filaments for successful FD processing and the approach taken in the development of a series of binder which meets these requisite properties for a wide range of ceramics and metals. Appropriate mixing and filament forming techniques are also discussed.

Piezoelectric ceramic/polymer composites were made by a fused deposition (FD) technique, which is a solid‐freeform fabrication (or layered manufacturing) technique where three‐dimensional (3‐D) objects are built layer by layer from a computer‐aided design (CAD) file on a computer‐controlled fixtureless platform. Indirect and direct FD methods were used to fabricate lead zirconate titanate (PZT)/polymer composites. For the indirect method, a CAD file for the negative image of the final part was created. A polymer mold was made via FD using a thermoplastic filament, and composite formation was completed via a lost mold technique. In the direct FD method, a thermoplastic polymeric filament that was filled with 50–55 vol% of PZT powder was used to form a positive image of the desired structure. Three‐dimensional honeycomb (“3‐D honeycomb”) composites and “ladder” composites with 3‐3 connectivity, which were formed via the FD technique, showed excellent electromechanical properties for transducer applications. In addition, the FD technique showed the ability to form composites with controlled phase periodicity, various volume fractions, and a variety of microstructures and macrostructures that are not possible with traditional composite‐forming techniques.

A technique for the rapid manufacture ofceramic components has been developed using rapid prototyping to generate molds for the required components. The process entails the fabrication offugitive tooling using rapid prototyping techniques from which ceramic articles are formed using gelcasting. In the gelcasting process, the mold cavities are filled with a fluid suspension of ceramic powder which sets to a solid form through the polymerization of gelling additives and application of heat. The mold is carefully removed by dissolution or heat treatment leaving the intact gelcast part. The "green" gelcast part is subsequently dried and sintered to full density. Computer aided manufacturing of the tooling using solid freeform fabrication techniques allows for complex shapes to be manufactured with minimal tooling cost. The technique is ideal for the manufacture of ceramic parts in small batch conditions or for prototyping of functional parts in design cycles. Cost and time reduction of a magnitude can be achieved.

Fused Deposition of Ceramics (FDC) and Metals (FDMet) are SFF techniques, based on commercial FDM(TM) technology, for rapid fabrication of functional ceramic and metal parts from powder/binder materials. This work demonstrates the possibility of applying FDC and FDMet to a variety of ceramic and metal particulate systems for fabrication of components/parts/devices for wide ranging, applications such as tooling, investment casting cores and shells, structural and functional components, etc. Several particulate ceramic and metal systems have been explored for FDC and FDMet The particulate systems explored vary in particle size from nano-crystalline (WC-Co) to coarse (>100 mu m SiO2) particles. The material systems explored for FDC and FDMet vary from conventional ceramic and metal systems such as SiO2 and stainless steel to advanced materials such as Si3N4 and PZT. FDC and FDMet of such a variety of material systems using a commercial FDM(TM) system has been made feasible by development of a unique series of binders, as well as optimized FD processing, binder removal techniques and sintering conditions.

Fused Deposition of Ceramics is an SFF technique based on commercial FDM(TM) technology, for fabrication of structural and functional ceramic components. This study describes, in derail, process improvements made in pre-FDC, FDC, and post-FDC fabrication steps to achieve functional properties in commercial GS-44 silicon nitride components. Microstructural characterization of sintered FDC parts reveals microstructures similar to conventionally processed silicon nitride material. Mechanical properties of FDC processed silicon nitride bend bars and roughness samples were evaluated. These property evaluation studies demonstrate that mechanical properties similar to commercial GS-43 silicon nitride materials can be achieved using FDC. The study also describes results achieved on fabrication of complex components from silicon nitride using FDC.

Solid freeform fabrication (SFF) is used to make 3-D components directly from computer-aided design (CAD) files. Many SFF techniques have been developed to fabricate parts and prototypes from CAD without hard tooling, dies or molds. Most of these techniques have been commercialized for fabrication of polymer and plastic parts for design verification and form and fit. Other SFF techniques are being developed for production of ceramic components with functional properties. One such technique, called fused deposition of ceramics (FDC), has been developed and demonstrated for structural ceramics. FDC is based on existing fused deposition modeling (FDM{trademark}) technology, commercialized by Stratasys Inc. (Eden Prairie, Minn.), for processing of polymers and waxes. High-green-density, simple- and complex-shaped silicon nitride parts have been formed by fused deposition of ceramics.