Zirconia-based composites for biomedical applications: Role of second phases on composition, microstructure and zirconia transformability

In order to develop ceria-stabilized zirconia (Ce-TZP) ceramics suitable for biomedical applications, composite materials should be developed. In this work, three different Ce-TZP-based composites were prepared by adding rounded α-Al2O3 grains and two kinds of elongated particles, SrAl12O19 and CeMgAl11O19. Composite powders were prepared through a surface coating route, which allowed a precise tailoring of chemical and phase composition as revealed by HRTEM. A limited cerium diffusion inside zirconia grains was revealed when CeMgAl11O19 was added to zirconia matrix. The role of second phases on the sintering behaviour, microstructural development and zirconia transformability was investigated. Second phases, particularly Al2O3, induce a delay in the zirconia densification. However, all composites presented a highly homogeneous and very fine microstructure. Strong differences in the morphologic features of the elongated grains between CeMgAl11O19 and SrAl12O19 were evidenced by FESEM. Vickers indentations hinted a strong difference in the efficiency of t–m transformation among the composites.