Multi-functionality of carbon nanotubes reinforced 3 mol% yttria stabilized zirconia structural biocomposites

The effect of the addition of carbon nanotubes (CNT) on the densification, microstructural, mechanical, wear performance and biocompatibility of 3 mol% yttria stabilized zirconia (3YSZ) have been investigated in the present study. The retention of high temperature phases (tetragonal and cubic) was found to increase with CNT addition in 3YSZ. Enhancement in the mechanical properties (hardness and elastic modulus) with CNT reinforcement is attributed to the refinement of grain size, enhanced densification and homogeneous distribution of CNT (up to 6 vol%). Correspondingly, fracture toughness increased from 5 MPa m^1/2 (in 3YSZ) to 10.1 MPa m^1/2 with CNT reinforcement (for 12 vol%) through energy dissipating mechanisms such as crack branching, CNT bridging, and crack-deflection, evidenced by the fractographs of 3YSZ-CNT composites. The toughening contribution with CNT reinforcement is observed to dominate over that of t→m transformation up to 38 times, evaluated using a modified fractal model. However, this effectiveness decreased with CNT agglomeration. The physical damage in the bacterial cell is observed to increase with CNT addition. The present findings promote 3YSZ-CNT as an optimal structural and antibacterial multifunctional biomaterial.