Support-Free Ceramic Stereolithography of Complex Overhanging Structures based on an Elasto-viscoplastic Suspension Feedstock.

Ceramic stereolithography (CSL) is an additive manufacturing method for creating ceramic three-dimensional (3D) objects via the layer-by-layer photopolymerization of a ceramic suspension. A key challenge in CSL is that support structures are required for building overhanging structures to prevent part damage or deformation caused by gravity or process-induced shears. Removing the support structures can result in issues such as poor surface quality, high risk of cracking, etc. To overcome this challenge, this article presents a new CSL-based ceramic fabrication method that uses an elasto-viscoplastic ceramic suspension as the feedstock material. The suspension's inherently strong interparticle resistive force can support overhangs without the need for building additional support structures; a temperature-controlled layer-coating module is designed to dynamically form a localized suspension bridge above the free surface of previously deposited materials, which allows for the application of fresh thin layers with a controlled shear force. The article presents material design and characterizations and discusses key process parameters and their effects on the geometry retention of fabricated overhangs. This new process provides the potential for fabricating ceramic 3D objects with complex overhangs, such as vascular networks, biomimetic heat exchangers, and micro-reactors.