Effects of adding yttrium nitrate on the mechanical properties of hot-pressed AlN ceramics

Aluminum nitride (AlN) ceramics were prepared by hot-pressing with Y(NO3)3·6H2O as sintering additive. The mechanical properties including flexural strength, Vickers’ hardness, and fracture toughness were studied. The relative density and mechanical property of the monolithic AlN were improved by adding Y(NO3)3·6H2O, which decreased the porosity. At 2 wt% Y2O3, the AlN ceramic exhibited the highest strength of 383 MPa, the highest hardness of 15.39 GPa, and the highest fracture toughness of 3.1 MPa m1/2. However, doping with more additive, the strength, hardness, and toughness of AlN ceramics decreased because of the weak interfacial bonding between AlN matrix and the yttrium aluminates phase.

► Y(NO3)3·6H2O was used to prepare AlN ceramics as sintering additive.
► The residual stress was discussed in sintered AlN ceramics.
► The interfacial bonding of AlN and yttrium aluminates phase was discussed.