Exploration of UHS Scalability by SPS approach: Multiphysics Simulation, Critical Dimensions, Mechanisms and Properties

Ultrafast High-Temperature Sintering (UHS) enables near-instantaneous densification of ceramics but is limited by part size, wall thickness, and cracking due to thermal inhomogeneities. This work introduces a scalable UHS approach using a modified Spark Plasma Sintering (SPS) chamber with a large working volume (∼113 cm3) and precise control, enabling the sintering of complex ceramic parts up to 30 mm. Direct Ink Writing (DIW) is employed to shape and debind components efficiently while preserving UHS advantages. A parametric study identifies optimal heating rates and critical wall thicknesses (≤1 mm) to minimize thermal stress. Finite element simulations link thermal gradients to stress development, offering predictive capability for complex geometries. The results reveal that organic binder decomposition strongly affects grain growth and residual porosity under ultrafast heating. This work demonstrates the feasibility of industrially scalable UHS and provides key insights for microstructure control and simulation-guided process design.