Enhanced mechanical properties in ZrO2 multi-walled carbon nanotube nanocomposites produced by sol–gel and high-pressure

Sol–gel processing and heat-treatment were used to obtain nanopowders with tetragonal phase of undoped zirconia reinforced with well-dispersed multi-walled carbon nanotube (MWCNTs), having contents between 1 and 5 wt.%. Amorphous nanopowders treated at 500 °°C crystallized in the tetragonal phase of zirconia with an average crystallite size of 25 nm. The nanocomposites containing 3 wt.% of MWCNTs reached 98% of the theoretical density, with an increase in hardness of about 15%, and a fracture toughness about 110% higher compared to the values obtained for pure zirconia compacted at the same conditions. The novelty in our study is the production of zirconia/MWCNTs nanocomposites with enhanced mechanical properties by compaction of nanopowders under high-pressure at moderate temperature.