Straightforward Design Strategy Towards 3D Near-Net-Shape Stoichiometric Sic Parts.

Fused Deposition Modeling (FDM), traditionally reserved for thermoplastics, is extending here to advanced non-oxide ceramics via a straightforward design strategy by considering the shaping and chemical richness offered by preceramic polymers. Specifically, 3D near net shape stoichiometric silicon carbide (SiC) objects are designed by manipulating the key features of a commercially available polycarbosilane (fusibility, high carbon content, relatively high SiC yield). In the early stage of the process, the carbon-rich polycarbosilane is first mixed with Si and SiC fillers and then thermolyzed at 120°C to increase polymer branching while offering tailored rheological properties during micro-extrusion and providing adequate shape retention once extruded. This allowed for the design of tailored and complex 3D complex polymer architectures with features down to 400 μm. The complex polymer parts are further converted into 3D stoichiometric SiC objects with quasi-near-net-shape - a volume shrinkage reduced to 9.1% has been measured - by heat-treatment at a temperature as low as 1400°C (argon flow). Given the flexibility to tune the preceramic polymer chemical and rheological properties, a new combined design approach is leveraged to generate bespoke advanced ceramics with a high freedom in geometry complexity. This article is protected by copyright. All rights reserved.