Chapter 10 - Fused deposition modeling of fully inorganic parts: Shaping, debinding, and sintering (SDS)

Abstract

Although originally conceived to process thermoplastic materials, the fused deposition modeling (FDM) technique, aka fused filament fabrication (FFF), can be extended to the production of fully inorganic parts. To this aim, a filament with a very high filler loading, typically exceed 45 vol% and often rangining between 55 to 60 vol%, is fed into the printer to manufacture the green part. Then the polymer matrix, which is just a sacrificial binder, is removed and the part is finally sintered to consolidate the inorganic phase. The binder removal is typically accomplished in two stages, since soluble or more volatile compounds are quickly removed prior to thermally debind the more stable compounds that constitute the so-called binder's “backbone”, which is responsible for the part's solidity until the inorganic phase starts to sinter. The process, which is known under several names, including fused deposition of ceramics (FDC), fused deposition of metals (FDMet) and shaping debinding and sintering (SDS), presents some similarity with powder injection molding (PIM). In spite of the analogy, shaping the object by 3-dimentsional (3D) printing, instead of injection molding, enables an unparalleled flexibility for customization. However, the part's design must be appropriately scaled up to compensate for the shrinkage occurring upon sintering, which often exceeds 12–15%. The FDM of fully organic parts offers an effective pathway for obtaining ceramic components and, owing to its affordability, may represent a valuable alternative to conventional metal additive manufacturing (AM) methods. As exemplified in this chapter, the numerous materials that are being proposed in the literature and in the marketplace clearly demonstrate the increasing importance of this technique.