Effect of MWCNTs on micromechanical and high-temperature tribological behavior of ZTA-MgO ceramic composites

Correlating the microstructure and tribo-mechanical properties is a promising approach for evaluating the performance of any newly decorated high-temperature materials. Aiming to improve the mechanical and tribological performance of zirconia toughened alumina (ZTA)- 0.6 wt% magnesium oxide (MgO) ceramic matrix, extremely low amounts (0.05 wt% and 0.1 wt%) of multi-walled carbon nanotube (MWCNT) is added into matrix. MWCNT-reinforced ZTA-0.6 wt%MgO composites are fabricated through a colloidal mixing followed by hot-press sintering at 1500 degrees C. The ceramic composites exhibit excellent tribo-mechanical properties attributed to the microstructural modification through the effective interaction between matrix and reinforcement phases including spinel (MgAl2O4) formation and MWCNTs. Perceptible improvement of hardness and fracture toughness ascribes to the collective strengthening mechanism. The advanced micromechanical interlocking mechanism for 0.05 wt% MWCNT-reinforced composite derives from the length reduction of MWCNTs during the powder mixing. The rolling action of MWCNT clumps evolves into a prominent three-body abrasive wear including crack bridging and crack arrest. This impeccable anti-wear and lubrication performance refer to decreasing wear rate of -81% and coefficient of friction of -29% even at 500 degrees C temperature making ZTA-0.6 wt%MgO-0.05 wt%MWCNT composite appropriate for high-temperature wear resistance applications.