Ultrafast, high-temperature sintering of 3D-printed ceramics

Ceramic components are widely used in biomedical, electronic, aerospace, and energy applications owing to their excellent mechanical, thermal, and chemical stability. Although digital light processing (DLP) enables the fabrication of complex ceramic geometries with high precision, conventional furnace sintering remains a major bottleneck due to long thermal cycles and high energy consumption. In this study, ultrafast high-temperature sintering (UHS) of alumina–silica ceramic specimens 3D-printed by digital light processing (DLP) was demonstrated. A UHS system utilizing Joule heating by carbon felt was fabricated in-house, and it was confirmed that heating rates of 10 4 –10 5 °C/min can be achieved, allowing the temperature to exceed 1,600 °C within just a few seconds. Observation of the thermal behavior of 3D-printed alumina-silica specimens showed that major binder decomposition occurred between 350 °C and 450 °C, with complete removal achieved at 650 °C. Accordingly, a three-step thermal treatment sequence was established, consisting of a two-step preheating at 450 °C and 650 °C—with the holding time at 650 °C varying from 30 to 270 seconds—followed by a final sintering at 1,100 °C. The sintering behavior under this sequence was comparatively analyzed. The optimal profile under the tested conditions achieved complete debinding and sintering of the 3D-printed ceramic samples within minutes, while delivering microstructural quality comparable to that heat-treated for 30 hours in a conventional furnace and showing no signs of carbon contamination. X-ray diffraction and Fourier transform infrared spectroscopy confirmed phase and chemical stability equivalent to conventional sintering, and mechanical tests showed comparable strength. The successful fabrication of a dental ceramic restoration using the UHS technique ultimately proved its industrial applicability as a quick and energy-efficient sintering process for the production of next-generation ceramic components.