Sintering behavior of aluminum nitride ceramics with MgO–CaO–Al2O3–SiO2 glass additive

• The small addition of 5 wt.% MCAS glass powder significantly promoted the densification of the AlN ceramics.
• Full densification of AlN could be obtained when the sample was sintered at 1600 °C.
• Sintering of AlN with MCAS glass was dominated by liquid phase sintering mechanism of the melted glass phase.

In this study, MgO–CaO–Al2O3–SiO2 (MCAS) glass oxide fabricated by a conventional melting process was used as a sintering additive to prepare dense AlN ceramics at lower temperatures. AlN specimen with 5 wt.% MCAS glass oxide was produced by sintering in a dilatometer and a conventional furnace. The sintering behavior of the glass-doped AlN was investigated by means of dilatometric analysis, X-ray diffraction analysis, and field-emission scanning electron microscopy microstructural observation. Results revealed that the melted glass phase had a significant effect on the densification of the AlN ceramics by a liquid-phase sintering. This led to a reduction in the sintering temperature by 200 °C from the 1800 °C required for conventional AlN–rare earth or –alkaline earth oxide system.