Effects of AlN content on mechanical and optical properties of AlON transparent ceramics

In this study, AlON powders with different AlN contents were synthesized by the carbothermal reduction nitridation method and used to prepare transparent AlON ceramics. Lattice parameters of AlON powders were calculated from XRD patterns to evaluate the effects on microstructure. The influences of the AlN content on the properties of the resulting AlON ceramics was investigated in aspect of density, mechanical properties and optical properties. With an increase in the AlN content, the density of the AlON ceramics increased, the grain size decreased, and the hardness and fracture toughness increased. Transparent AlON ceramics were obtained at the AlN content of 21.6-29.7 mol%. The refractive index of the AlON ceramics increased from 1.688 to 1.702 at 4000 nm with an increase of AlN content. The correlation between the composition and properties of the AlON ceramics obtained in this study will provide both theoretical and experimental reference for industrial AlON ceramic manufacturing.