Resumen:
This work describes the microstructure and fracture toughness of zirconia toughened alumina (ZTA) nanocomposite in which multi-wall carbon nanotubes (MWCNTs) and nanosized ZrO2 particles were used as reinforcement. The ZTA nanocomposites with additions of 0, 0.005, and 0.01 wt.% MWCNTs and 2 wt.% nanosized ZrO2 particles were pressureless sintered in an anti-oxidant sagger with graphite powder bed at 1520 degrees C during 1 h in air and then HIPed at 1475 degrees C in argon atmosphere 1 h at a pressure of 150 MPa. Relative densities ranging 94-98% were reached. In HIPed composites the hardness and fracture toughness values were increased up to similar to 17% and similar to 37%, respectively, compared to the "as sintered" composites free of carbon nanotubes. A combined fracture mode, crack deflection, pull-outs of a small amount of carbon nanotubes, and bridging effect were the mechanisms leading to the improvement in fracture toughness. (C) 2009 Elsevier Ltd. All rights reserved.
