Effects of sintering additives and sintering methods on the mechanical, antimicrobial and optical properties of Si 3 N 4 bioceramics

Si 3 N 4 bioceramics were fabricated using GPS and SPS method with MgO-RE 2 O 3 (RE = La, Nd, Gd, Ho and Lu) sintering additives. The effect of sintering methods and sintering additives on the grain growth, mechanical, antimicrobial properties and color of Si 3 N 4 bioceramics were studied. Samples sintered with GPS are composed of 13-Si 3 N 4 and samples sintered with SPS are composed of alpha-Si 3 N 4 and 13-Si 3 N 4 . The growth of 13-Si 3 N 4 grains in samples sintered with GPS are more adequate. Samples sintered with GPS exhibit a S. aureus inactivation rate up to 98% and a bright color appearance with a hardness of about 13 GPa and a fracture toughness up to 7.5 MPa m 1/2 , suitable for dental implants. And samples sintered with SPS exhibit a hardness of about 17 GPa and a fracture toughness about 6 MPa m 1/2 .