Rapid fabrication of Si₃N₄ ceramics with gradient appearance and microstructure

Si3N4 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 Si3N4 ceramics, the & beta;-phase content gradually changed from 84% to 11%. The Si3N4 ceramics exhibited white color on one side and showed a hardness of 19 GPa and fracture toughness of 7 MPa & BULL;m(1/2) and may be suitable for bio-implantation applications.