Surface properties of Al2O3-YSZ ceramic composites modified by a combination of biomimetic coatings and electric polarization

Alumina-containing yttria-stabilized zirconia composite (Al-YSZ) has a higher flexural strength than YSZ, although Al-YSZ cannot directly bond with bone tissues. To expand the biomedical applications of Al-YSZ, new surface modifications were investigated to improve the bioactivity in the present study. The combination of a biomimetic coatings method using an alternate soaking technique and electric polarization treatment was performed on Al-YSZ. The crystalline phases of the starting Al-YSZ sintered disks were assigned to tetragonal ZrO2 and α-Al2O3 phases. The analyses of the electrical properties were carried out using complex impedance and thermally stimulated depolarized current measurements for polarization treatments. Our results indicate that the stored charges in Al-YSZ via polarization decreased in YSZ, because of the added alumina, while the calcium phosphate film deposited by the biomimetic coatings method on polarized Al-YSZ was observed to be thicker than the non-polarized film. The coating method would be suitable for the complex geometry of biomaterials. As a result, polarized Al-YSZ fabricated using an alternate soaking process is expected to be useful as a biomaterial under load-bearing conditions.