Fabrication of 15R AlN-polytypoid ceramics

摘要

The formation, densification behavours and mechanical properties of 15R AlN-polytypoid (SiAl_6O_2N_6) were studied. The results show that 12H(SiAl_5O_2N_5) occurs as a second phase during the formation of 15R. The additives Sm_2O_3 or Nd_2O_3, especially combined with Al_2O_3, can effectively promote the densification of 15R. Both the highest hardness of 12.80 GPa and fracture toughness of 4.8 MPa m~1/2 occur in the 15R composition with 2.5 wt./100 SmAlO_3 as sintering additive.