3D printing of ceramic substrates: a cross-platform comparison between direct ink writing (DIW) and digital light processing (DLP) technologies

This study presents a comparative analysis of ceramic honeycomb substrates fabricated using two additive manufacturing (AM) techniques: Direct Ink Writing (DIW) and Digital Light Processing (DLP). By varying key printing parameters (nozzle diameter for DIW and layer thickness for DLP) and binder formulation, the effect of the manufacturing technique on the microstructure, dimensional stability, and mechanical performance of sintered substrates were systematically investigated. In DIW, reducing the nozzle diameter from 800 to 600 μm led to a consistent increase in compressive strength, attributed to favorable load-bearing distributions. One ink system showed no microstructural variation while the other exhibited phase separation when printed with a smaller nozzle, indicating sensitivity to rheological stability. Nevertheless, compressive strength was primarily influenced by nozzle size, and when the same nozzle size was used, there were negligible differences between the two ink formulations. In DLP, layer thickness strongly influenced both microstructure and mechanical properties. Samples printed with finer layers (25 μm) showed smoother surfaces, reduced stair-stepping, and higher compressive strength in comparison to samples printed with 50 μm layers. These differences were attributed to improved interlayer bonding due to higher vertical overcuring. However, this also led to greater lateral overcuring and strut thickening. Binder composition played a secondary role in DLP but had a more noticeable impact on structures with finer features. Overall, the findings show that even with identical feedstock, the inherent deposition mechanism of each AM technique governs how resolution and geometry translate into strength, revealing clear pathways to tune ceramic substrate performance by aligning process choice with the target mechanical and dimensional requirements.