Energy‐Efficient Microwave Sintering of Binder‐Jetted Alumina

ABSTRACT Microwave (MW) sintering offers an energy‐efficient approach for densifying Al 2 O 3 ceramics. However, its adoption for ceramics 3D‐printed via binder‐jetting remains limited due to uneven heating, particularly in complex geometries. SiC susceptors improve thermal uniformity, but induce charge concentration and local hotspots, requiring careful control. Here, multiphysics models are combined with experiments to control hotspots and uniformly sinter binder‐jetted Al 2 O 3 using 2.45 GHz MWs. We developed electromagnetic wave‐heat transfer models to investigate how SiC susceptor configurations influence Al 2 O 3 heating. Simulations revealed that hexagonal configuration minimized sample temperature non‐uniformity (∼20°C), while square configuration suppressed localized hotspots. With reduced overheating, we experimentally sintered binder‐jetted blocks across 1300°C–1500°C, achieving ∼75%–86% relative density with microstructures and α‐alumina phases similar to conventional sintering, while at 1500°C shrinkage (∼65%–66%) was also comparable, reducing hold time from 6 h to 7.5 min. Extending to complex geometries, we applied the optimized process to evenly heat and sinter binder‐jetted spur gears, widely used in aerospace, achieving mechanical strength (∼54 N tooth‐failure load and ∼24.5 MPa maximum bending stress) comparable to its conventional counterpart (∼50 N tooth‐failure load in our study and ∼24.5 MPa bending stress reported in prior studies). Unlike previous MW sintering studies, the results enable uniform, hotspot‐controlled MW sintering of 3D‐printed ceramics. The ∼48x faster processing and ∼96% lower energy use than conventional, reinforces it as a scalable, electrified route for high‐throughput, decarbonized ceramic manufacturing.