Effect of rare earth oxides addition on the mechanical properties and coloration of silicon nitride ceramics

摘要

The aim of this study was to evaluate the mechanical properties and coloration of silicon nitride ceramics in the presence of RE2O3 (RE = Nd, Eu or Dy). Dense Si3N4 ceramics were prepared by gas pressure sintering at 1800 degrees C for 2 h. XRD analysis confirmed the complete transformation of alpha-Si3N4 to beta-Si3N4. The fracture toughness and flexure strengths were 11.93 +/- 0.56 MPa.m(1/2), 667 +/- 40.98 MPa with the addition of Eu2O3 (SE). Base on the SEM image, the pull-out, bridging and deflection of large grains were observed and contributed to the increase in mechanical properties. The chromaticity of sintered bodies was measured using a spectrophotometer. The color difference of the ceramics is due to the formation of different color developing compounds according to the EDS. Results showed that high-toughness and colorful Si3N4 ceramics can be prepared using YAG:Ce3+ as sintering additive and RE2O3 as the colorant.