Effects of Behaviors of Aluminum Nitride Ceramics with Rare Earth Oxide Additives

The effects of three types of additives, Y2O3, Nd2O3 and Er2O3 on the behaviors of AlN ceramics were investigated. The experimental results showed that the sintering temperature could be decreased and the mechanical behavior could be improved by adding rare earth oxide in AlN ceramics. The highest strength and fracture toughness of AlN ceramics with 2% Y2O3 addition were 311 MPa and 3.5 MPa·m1/2, respectively. Second phase of AlN ceramics with Y2O3 addition was identified as Y3Al5O12 formed by the reaction with Al2O3, meanwhile that with Nd2O3 was identified as NdAlO3. The fracture behavior of AlN ceramics with Y2O3 and Nd2O3 were a mixed mode of transgranular fracture and intergranular fracture. Because of the high evaporation rates of Er2O3 (1.2 × 10−5 g·cm−2), no aluminium erbium oxide was found in the AlN ceramics doped with Er2O3. So the dielectric loss tanger(tanδ) and thermal conductivity of AlN ceramics doped with Er2O3 were best.