Straightforward Design Strategy toward 3D Near‐Net‐Shape Stoichiometric SiC Parts

Abstract

AbstractFused deposition modeling (FDM), traditionally reserved for thermoplastics, is modified here with a granule‐based extrusion head to be extended to advanced nonoxide ceramics via a straightforward design strategy that considers the shaping opportunities and the 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 the subsequent extrusion process at 90 °C and adequate shape retention once extruded. This allows for the design of tailored and complex 3D complex polycarbosilane‐based architectures with features down to 400 µm. Polymer‐based parts are further converted into 3D stoichiometric SiC objects with quasi‐near‐net‐shape—a volume shrinkage reduced to 9.1% is 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.