Effect of La(2)O3 addition on densification behavior and properties of Mg-doped sialon

摘要

Mg-doped sialon ceramics with three compositions were hot pressed at 1850 degrees C for 1 h, using La2O3 as a sintering additive. Full density was achieved in these samples. The influence of La2O3 on densification behavior, phase assemblage, microstructure, and mechanical and optical properties were investigated. La2O3 addition could enhance the densification by supplying more low-viscosity liquid phase. Moreover, the development of elongated beta-sialon grains was also facilitated mainly due to the segregation of La to prismatic plane. The La2O3-added samples exhibited high hardness (20 GPa) and fracture toughness up to 4.9 MPa.m(12). Besides, high transmittance of similar to 48% was also achieved even if a certain amount of glassy phase remained. This was explained by the increased refractive index of La-containing glassy phase, which reduced light scattering.