Low Shrinkage Hydrogel Infusion Additive Manufacturing of Ceramics and Metals

Vat photopolymerization (VP) is a powerful tool for the fabrication of architected ceramic and metal structures. However, conventional methods of ceramic/metal VP, such as with the use of slurries or organic-inorganic hybrid resins, have challenges with viscosities, light-scattering, and limited material compositions. Recently, the use of metal-salt solutions has emerged as a promising approach for the VP of ceramics and metals. While versatile and accessible, the process is accompanied by a significant amount of shrinkage, which causes warping, porosity, and structural damage. Here, we present Hydrogel Infusion Additive Manufacturing Generation 2 (HIAM G2), a versatile technique for fabricating dense architected ceramics and metals with low conversion linear shrinkages. Central to our method is a post-fabrication repeated infusion-coprecipitation process that allows us to progressively increase the metal loading in 3D “blank” hydrogels. Thermal treatment of these high metal content hydrogels then converts them into ceramic or metal architectures. To demonstrate this, we fabricate Fe2O3 and Fe gyroid structures with overall linear shrinkages of 20% and 38% respectively, with theoretical densities of 89% and 88% respectively. HIAM G2 thus enables the VP of dense high-quality ceramics and metals, which could pave the way towards the fabrication of advanced architected materials and devices.