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

Abstract

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 2 wt % MWCNTs were prepared by spark plasma sintering (SPS) at 1400°C under 40 MPa 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 aluminabased 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 ³18 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.

Spark Plasma Sintering of Nano Silicon Carbide Reinforced Alumina Ceramic Composites

“…During the SPS process, the densification occurring in the powders with the increase of temperature at constant pressure is determined from the displacement amount of the graphite punches due to the shrinkage. After a certain temperature value that is different for each material and composition, the shrinkage is completed and remains constant [6,8]. Therefore, in order to obtain a dense structure, the sintering temperature should be equal or higher than the temperature at which shrinkage is completed.…”

“…4. The hardness increased from 18.27 GPa to 22.83 GPa.5.While the fracture toughness of the monolithic Al 2 O 3 was 2.94 MPa•m 1/2 , a maximum value of 6.09 MPa•m 1/2 was obtained with the addition of nano-SiC 6…”

“…This negative feature limits the use of Al 2 O 3 . On the other hand, there are many studies to increase the fracture toughness of Al 2 O 3 based ceramics through microstructure control and reinforcement phase mechanisms [1,3,4,[6][7][8][9]. The reinforcement phase mechanism of Al 2 O 3 matrix is occurred by secondary phases in the forms of particle and/or fiber.…”

The Effects of MWCNT Addition to Physical Properties of ZTA-MgO Cutting Tool

“…CNTs diameter are as low as 1 nm with a tensile strength of up to 200 GPa and stiffness more than 1 TPa [3]. In addition to the excellent mechanical properties, it also possesses superior electrical (>1.5 x 104 S/m) and thermal properties (>2000 W/mK) [4]. The introduction of such high thermal conductive materials as reinforcement in Al2O3 could serve as a uniform thermal energy distribution hub in the matrix which leads to higher densification and improvement in mechanical properties [5].…”