The Preparation and Properties of Functionally Graded Alumina/Zirconia-Toughened Alumina (ZTA) Ceramics for Biomedical Applications

摘要

Functionally graded alumina/zirconia-toughened alumina (ZTA) ceramics for biomedical applications were designed with a hard, wear-resistant alumina surface and a tough, zirconia-rich core. The main goal was to achieve an improved mechanical performance by introducing a residual compressive stress in the outer surfaces. Symmetrical, 7-layered samples were prepared by the sequential slip-casting of specimens from suspensions prepared at the inherent pH values, close to the pH values at which the maximum (negative) zeta-potential was measured. No sintering or tunneling cracks were observed in the samples, but large defects, such as big agglomerates, air bubbles and large circular pores at layer interfaces, which, resulted from preparing the samples using the slip-casting technique, were readily observed. The strength of the symmetrical composites is influenced by the presence of defects, which most probably originate from the shaping process. Therefore, the defects have to be regarded as the reason why the strength of the 7-layered composites is low.