Developing a Framework to Qualify Additively Manufactured Ceramics: Effect of Sintering Temperature on Feature Resolution, Shrinkage, and Flexural Properties

Functional applications for additively manufactured ceramic parts are currently limited by both material constraints and knowledge of process-structure-property relationships. One challenge for developing new ceramics for additive manufacturing (AM) is determining a post-process debinding and sintering strategy that yields parts with sufficient mechanical strength while mitigating defects and unpredictable shrinkage. This work investigates how maximum sintering temperature (varied between 900°C and 1300°C) affects material and mechanical properties of parts fabricated using a commercial silica-based resin and the vat photopolymerization AM process. A custom test artifact was designed to probe dimensional accuracy and survivability of features of different sizes, shapes, and orientations. The shrinkage of cubes with 1 cm sides was generally proportional to sintering temperature and did not exceed 18% in any dimension. The shrinkage was more isotropic up to 1100°C, but at higher temperatures, Z shrinkage was typically ~30% higher than X and Y shrinkage. Parts with higher maximum sintering temperatures experienced higher flexural strength and lower strain at break in three point bend testing. Regardless of maximum sintering temperature, most parts exhibited some degree of cracking or delamination. X-ray computed tomography was used to probe internal porosity, and several voids were observed even when sintered to 1300°C. Fundamental understanding of how sintering affects parts’ structure and properties will enable development of a framework to qualify ceramic AM materials and processes. This knowledge will facilitate predictable part performance, helping to ensure reliability of future parts for functional applications.