Investigation of the microstructure, mechanical properties and cell viability of zirconia-toughened alumina composites reinforced with carbon nanotubes

The addition of multi-wall carbon nanotubes (MWCNTs) to ceramic matrices can be utilized for special applications such as implant materials. In this study, zirconia toughened alumina (ZTA) composites having 10, 20 and 30 vol% yttria stabilized zirconia (YSZ) with additions of 0.5, 1, and 2wt% MWCNTs were prepared by spark plasma sintering (SPS) at 1400 degrees C under 40MPa for 5 min. Systematic investigation of the effects of CNT reinforcement on densification behavior, microstructure, mechanical properties (Vickers microhardness, indentation fracture toughness, and flexural strength) and biocompatibility (cell viability) of ZTA composites was performed. The results indicated that the mechanical properties of CNT reinforced alumina-based composites are strongly dependent on the amount and position of nanotubes in the microstructure and the strength of the cohesion of matrix grains and the nanotubes. Composites with 30 vol% YSZ and 0.5 wt% CNTs exhibited the highest Vickers hardness, fracture toughness and flexure strength with values of similar to 18 GPa, 5.5 MPa.m(1/2) and 590 MPa, respectively. In addition, preliminary biocompatibility tests indicated that the composites showed no cytotoxicity to human osteoblast cells. (C) 2015 The Ceramic Society of Japan. All rights reserved.