The effect of different rare earth oxides on mechanical and optical properties of hot pressed α/β-Sialon ceramics

The effect of Y2O3 and different REOs (La2O3, Nd2O3 and Er2O3) on mechanical and optical properties on Sialon ceramics was studied. Duplex α/β-Sialon ceramics were revealed by XRD patterns in sintered body. α-Sialon phase was increased abruptly with the addition of Y2O3 and different REOs. Mechanical properties were also increased with the addition of REOs as compared without REOs. The crystallization at the triple junction with Y2O3 added Sialon was observed by TEM, which may be related to the slow cooling rate in hot press sintering process. Slow cooling rate causes the crystallization of glassy phase that occurred in grain boundaries and triple junctions. Crystallization of glassy phase enhances the mechanical properties of the material. Y2O3 had the positive effect on densification and mechanical properties. Mg-α/β-Sialon composite shows higher light transmission in NIR region than any other composition but better mechanical properties were shown by other compositions.