Rapid fabrication of Si 3 N 4 ceramics with gradient appearance and microstructure

Abstract Si 3 N 4 ceramics with tailored gradient in color and microstructure were prepared by a rapid cost‐effective one‐step approach. The gradient microstructure was obtained by the manipulation of the dissolution‐reprecipitation process, by controlling the sintering temperature and sintering additive content. In the Si 3 N 4 ceramics, the β‐phase content gradually changed from 84% to 11%. The Si 3 N 4 ceramics exhibited white color on one side and showed a hardness of 19 GPa and fracture toughness of 7 MPa·m 1/2 and may be suitable for bio‐implantation applications.