Ultrafast high-temperature sintering of aluminum nitride

Ultrafast high-temperature sintering (UHS) has received significant attention due to its effectiveness in consolidating ceramics in a very rapid manner. However, the application of UHS to non-oxide materials has been limited due to their extremely low sinterability. In this study, the UHS technique was applied to AlN to demonstrate its applicability and examine the resulting microstructure evolution and mechanical properties. High densification was achieved using electric currents of 47 A, 50 A, and 53 A for 240 s, with corresponding specimen temperatures of 1807.5 °C, 1872.8 °C, and 1935.6 °C. Vickers hardness increases up to 240 s but decreases at 300 s due to grain growth and sublimation of secondary phases. Fracture toughness decreases with larger grain sizes showing the inverse relationship between grain size and toughness. This study demonstrates that UHS is applicable to non-oxide ceramics, which offers significant potential for energy savings and rapid processing in non-oxide ceramic manufacturing.