UC San Diego

Sintering, the process of bonding powder materials through thermal activation, is a critical step in the production of both ceramic and metallic components. Although traditionally viewed as a stage aimed at densification, sintering also plays a fundamental role in strengthening, shaping, and microstructure development. Emerging manufacturing strategies increasingly emphasize rapid and energy-efficient sintering approaches. This research explores the control of microstructure evolution during sintering by tailoring the mode and characteristics of energy-input. Beginning with low energy-input process, this work investigates the steady sintering of binder jetting materials routes, focusing on their inherent microstructural anisotropy and evolution during sintering process of 3D-printed materials. The study examines how low-energy free sintering conditions affect the microstructural development of these printed parts. Innovative methodology including binder-free printing and ultra-fast sintering is proposed for improved binder jetting procedure. Moving to intermediate energy-input regimes, spark plasma sintering (SPS) is employed to realize energy-modulated densification, with particular emphasis on cyclic phase transitions (CPT) as a mechanism for enhancing densification and tailoring microstructure of complex concentrated alloys (CCAs). At the extreme end of energy-input modality, a self-developed technology, electric nano pulsing (ENP), is utilized to achieve quasi-instantaneous and localized microstructure modification through the application of electropulsing with ultra-high intensity and ultra-short pulse durations. The study of ENP processing also provides insights into next-generation, ultra-rapid sintering and materials modification techniques. Collectively, this research systematically demonstrates how tailoring energy-input in terms of magnitude, temporal profile, and spatial distribution provides a powerful approach for controlled microstructure evolution during sintering.