The Role of Materials Processing Variables in the FDC Process

The Fused Deposition of Ceramics (FDC) is based on the commercially available Fused Deposition Modeling (IDMTM) technique developed by Stratasys Inc. The FDC process is being currently developed to make complex ceramic parts in an automated fashion. Although the current focus is on making SisN4 parts, this technique has been successfully used to make electroceramic (such as PZT) and metallic (such as stainless steel) parts. As feedstock for the IDC process, filaments loaded with 55 vol% GS-44 Si3N4 is being used. For the filament to be used in the IDC process, it must possess a unique combination of physical, rheological and mechanical properties. In this paper, we investigate the role played by some of the process variables on these properties. Our current processing sequence to make filaments is as follows - coating of powders with a surfactant, compounding the ceramic and binder, extrusion into filaments and finally treatment of filaments to achieve requisite properties. The study has resulted in improvements to the quality of the filament which can be used for automated FDC. The effect of moisture, agglomerates and filament aging on FDC will be discussed.