Optical and mechanical properties of Mg-doped sialon composite with La2O3 as additive

Using 0.5 wt.% La2O3 as a sintering additive, Mg-doped sialon composite with the maximum infrared transmittance of 50% was fabricated by hot pressing at 1800 °C. The addition of La2O3 significantly promotes the densification process of Mg-doped sialon and the anisotropic growth of β-sialon grains. As a result, the sintered material exhibits high hardness (20.2 GPa), fracture toughness (4.8 MPa m1/2) and flexural strength (664 MPa). Furthermore, the nano-sized glassy phases concentrated at triple junctions have no obviously negative impact on infrared translucency of Mg-doped sialon.