Solvent- and binder-free additive manufacturing of polymer-derived ceramics: Rheological tuning and structural performance

Silicon carbide (SiC) ceramic matrix composites are widely used in aerospace applications due to their high strength, heat resistance, and corrosion resistance. However, traditional machining methods make it challenging to fabricate complex shapes. This study presents a solvent-free and binder-free direct ink writing (DIW) method for producing SiC/SiOC composites using polycarbosilane SMP-10, a preceramic polymer that acts as both the ceramic precursor and the liquid phase, thereby eliminating the need for volatile solvents and sacrificial binders. By adjusting the SiC content, printable ink formulations were developed, and their flow properties were analyzed. The influence of geometric factors, such as inter-wall spacing and base layer width, on structural stability was also examined. Wider base layers provided greater support, increasing the maximum printable height before failure, while structures with larger inter-wall spacing were more prone to collapse due to reduced lateral support. These findings highlight the importance of structural design in achieving stable and precise prints. The printed lattice structures exhibited compressive strength of 5.62 ± 1.75 MPa – 9.62 ± 1.10 MPa and density of 2.05 – 2.34 g/cm³, alongside exceptional thermal insulation and stability. This approach offers an easy and efficient method for fabricating complex ceramic structures with excellent mechanical and thermal performance, making it highly relevant for advanced aerospace and high-temperature applications.