Sintering of aluminum nitride by using alumina crucible and MoSi2 heating element at temperatures of 1650 °C and 1700 °C

Aluminum nitride (AlN) ceramics, prepared with Y2O3 and CaO sintering additives, have been densified in an Al2O3 crucible at temperatures of up to 1650 °C and 1700 °C using a conventional MoSi2 heating element furnace. The results of this study show that relative densities in excess of 99% of theoretical and a relatively high-thermal conductivity of 147 W m−1 K−1 have been achieved for feedstock materials prepared with combined addition of 1 wt.% Y2O3 and 1 wt.% CaO. All of the phases in sintered samples have been shown to be crystalline AlN and minor amount of secondary phases, were detected such as enriched Y- and Ca-aluminates by the XRD patterns, back-scattered imagery and microprobe analysis. The advantage of using the particular experimental system and sintering condition is considered to be amenable to lower production cost and enhance the feasibility of mass production. Critical temperature for AlN densification to obtain the highest density is about 1650 °C.