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The development of the ceramic slurries based on silicon nitride (Si3N4) powders involved several steps Recently the great interest in ceramic materials is leading to extend the application of Additive Manufacturing (AM) technology, widely known and developed for metals and polymers, to this class of materials. Indeed, AM allows to minimise both the amount of material used for forming complex-shaped component layer by layer and post-process working. Therefore, AM also minimises costs, energy consumption and process time, making the entire production process highly sustainable. A promising AM shaping technique for advanced ceramics is Digital Light Processing (DLP): a photosensitive liquid resin is filled with ceramic powder and selectively polymerized layer-bylayer by means of the light of a projector, to obtain a near-net-shape object, after the debinding and sintering processes. In this work an optimized Si3N4based slurry was developed. Its properties were fine-tuned both for the specific DLP technique and for obtaining ceramic materials and components for highperformance applications. Therefore, the developed slurry Si3N4-based allows to fully exploit the characteristics of advanced ceramics, then their use for applications that require a combination of high thermomechanical properties, and at the same time, the advantages of DLP technology, to create complex shapes and reduce post-forming processing and material consumption. Selection and mixing of raw materials: functionalised monomers dispersants photoinitiators ceramic powders typologies Rheological characterisation of the slurries Identification of the most appropriate material slurry constituents percentages Fine-tuning of the 3D-printer parameters Verification of the slurry printability Printed standard geometries Ceramic slurries preparation Optimisation of layer height and curing time Development of ceramic slurries, with optimised properties for the specific shaping technique, DLP, and intended for making components for high-performance applications (i.e., in term of high thermomechanical characteristics) an optimised slurry with high ceramic powders content and suitable dispersants, photoinitiator and resin percentages, to obtain satisfactory properties in terms of viscosity, density and printability. Innovative aspects: The developed ceramic slurry for DLP based on Si3N4is an innovative material because the ceramic feedstocks for AM are currently few and not widely commercially available The use of 3D-printing for technical ceramics represents a sustainable solution, thanks to the overcoming of the conventional production process limits (e.g., onerous post-forming processing) Optimised ceramic slurry properties Accurate selection of ceramic particles distribution High solids content with optimal and adequate stability 45 vol% Satisfactory viscosity level for 3D printing process ≤ 5 Pa*s ( shear rate [1-20] s-1) Rheological characterisation and printing tests campaign Content [vol%] Slurry composition 45 Si3N4(87 wt%) Powders Al2O3 (5 wt%) Y2O3 (8 wt%) 49.6acrylate monomers Resin 1.5phosphine oxide, TPO Photoiniziator 3.9phosforic acid ester Dispersing agent [email protected] ENEA - Research Laboratories Faenza Via Ravegnana 186, 48018 Faenza (Italy) This research has been supported by the Italian Ministry of Environment and Energy Security (MASE) through the projects “1.4 Materiali di frontiera per usi energetici” (CUP: I53C22003040001), WP4 - Additive manufacturing di materiali ceramici avanzati per incrementare l’efficienza di sistemi di produzione di energia, within the Three-Year Plan 2022-2024 of the National Electric System Research Fund Dong, X., Wu, J., Yu, H., Zhou, Q., Wang, W., Zhang, X., Zhang, L., Li, L., He, R., Additive manufacturing of silicon nitride ceramics: A review of advances and perspectives, Int J Appl Ceram Technol. 2022;19:2929–2949. Kowsari, K. et al., Photopolymer formulation to minimize feature size, surface roughness, and stair-stepping in digital light processing-based three-dimensional printing, Addit. Manuf. 24 (2018) 627–638. Ge, Q., Jian, B., Li, H., Shaping soft materials via digital light processing-based 3D printing: a review, Forces Mech. (2022), 100074. Zhangwei C., Ziyong L., Junjie L., Chengbo L., Changshi L., Yuelong F, Changyong L., Yang L., Pei W., Yi H., 3D printing of ceramics: A review, Journal of the European Ceramic Society, Volume 39, Issue 4,2019,Pages 661-687 Castro e Costa, E., Pinto Duarte, J., Bártolo, P., A review of additive manufacturing for ceramic production, Rapid Prototyping Journal, https://doi.org/10.1108/RPJ-09-2015-0128. Permanent: https://doi.org/10.1108/RPJ-09-2015-0128 Liu, Y., Zhan, L., Wen, L., Cheng, L., He, Y., Xu, B., Qiumei Wu, Q., Liu, S., Effects of particle size and color on photocuring performance of Si3N4 ceramic slurry by stereolithography, Journal of the European Ceramic Society, Volume 41, Issue 4, 2021, Pages 2386-2394 Curing time
