Evolution of debinding and sintering of a silica-based ceramic using vat photopolymerization additive manufacturing

Abstract

One challenge in developing new ceramics for additive manufacturing (AM) is determining a post-process heating strategy (including debinding and sintering) that produces parts with sufficient mechanical strength while mitigating defects and unpredictable shrinkage. In this work, the authors explore how modifying debinding and sintering parameters (e.g., temperatures, hold times, and rates) affects material and mechanical properties of parts fabricated using a commercial silica-based resin and the vat photopolymerization AM process. Parts were qualitatively assessed for effective debinding before being subjected to different sintering conditions. Tradeoffs between time and temperature were observed during both debinding and sintering phases. Strong correlations between thermal schedules and density, shrinkage, porosity, and flexural properties were observed in sintered parts, where increasing sintering temperature, hold time, and rate generally increased density, shrinkage, and flexural strength. Average densities ranged from 1.27 to 2.01 g/cm³ depending on the selected debinding and sintering strategy. The condition with the highest density, which heated to 1300°C at 300°C/h, yielded the lowest porosity (∼11 %), shrinkage of ∼15 % (XY) and ∼20 % (Z), flexural strength of ∼28 MPa, and flexural strain at break of ∼0.11 %. The novelty of this work is the systematic investigation of the effects of different temperatures, hold times, and ramp rates for both debinding and sintering on density, porosity, shrinkage, and flexural properties in ceramic AM. Fundamental understanding of how post processing affects ceramic AM parts will enable establishment of guidelines on how to strategically select post-process conditions for new ceramics. This knowledge will support predictable part performance and contribute to a framework that expands the applicability of ceramic AM parts for functional applications.