Digital light processing 3D printing of surface-oxidized Si3N4 coated by silane coupling agent.

Due to high light absorption and high refractive index of silicon nitride (Si₃N₄) ceramic, it is difficult to prepare Si₃N₄ slurry with favorable curing ability, high solid loading and low viscosity at the same time, and thus the high-quality Si₃N₄ parts are hard to fabricate via Digital Light Processing (DLP). In this paper, the oxidation process was used to enhance the curing behavior of Si₃N₄ slurry, and then silane coupling agent (KH560) was used to improve the rheological properties of the oxidized Si₃N₄ slurry. The effect of Si₃N₄ slurry with oxidation and modification on its rheological behavior, light absorption, curing ability and stability have been systematically investigated. A Si₃N₄ slurry with abundant photocuring ability, high solid loading, low viscosity and reliable stability was fabricated by the oxidized (1 h) and KH560 (1 wt.%) modified Si₃N₄ powders, and the dense Si₃N₄ ceramic parts were produced by this slurry via DLP 3D printing. Subsequently, the influence of oxidation and modification on microstructure, mechanical properties and thermal conductivity have been investigated. Finally, the microstructure and performances of Si₃N₄ ceramic were compared between different forming processes (including: DLP and cool isostatic pressing). [ABSTRACT FROM AUTHOR]