Fabrication of aluminum nitride ceramics via digital light processing

Aluminum nitride (AlN) ceramics are increasingly utilized across various applications due to their exceptional theoretical thermal conductivity. To enable the fabrication of AlN ceramics with customized structures, digital light processing (DLP) technology has been explored for producing complex geometries. However, challenges arise due to AlN’s high refractive index and susceptibility to moisture absorption, which affect the curing characteristics and rheology of AlN slurries used in DLP. This study systematically examined the curing behavior and rheological properties of AlN slurries. Initially, the impact of photosensitive resin compositions and photoinitiators on curing depth and excess width were investigated. The results revealed that with a resin mixture ratio of 3:4:3 (mixed resin, high refractive index resin, and 9,10-Diphenylanthracene) and the addition of 5wt% of 2,4,6-trimethylbenzoyl-diphenyl phosphine oxide, the optimal curing depth of 90 μm was achieved, with an excess width of less than 0.1 mm. Additionally, the incorporation of 3wt% KH560 reduced the sedimentation rate and viscosity. The AlN slurry with 50vol% solid loading was prepared with the high curing depth of 73μm and low viscosity of 20.5 Pa.s at the shear rate of 27s -1 . Subsequently, the effects of buring powder for debinding process was investigated. Finally, a AlN ceramic body with a porosity of 2.97 %, bulk density of 3.08g/cm 3 , and flexural strength of 107.2MPa was obtained upon sintering at 1900 °C for 4 h.