Influence of MgO/MWCNTs incorporation on the physical, mechanical characteristics, and microstructural response of ZTA composite

This study examines the impact of MgO and Multi-Walled Carbon Nanotube (MWCNT) reinforcements on the mechanical, microstructural, and physical properties of Zirconia-Toughened-Alumina (ZTA) composites. These composites were synthesized via microwave sintering (MWS) by compressing powders at 100 MPa and sintering at temperatures ranging from 1300 degrees C to 1550 degrees C for 20 min without applied pressure. The addition of 1 vol% MWCNTs and 10 vol% ZrO2 in the Al2O3 matrix resulted in the smallest nominal grain size due to the grain growth inhibition by MWCNTs, producing a refined microstructure. Composites with 1 vol% MgO/MWCNTs and 10 vol% ZrO2 exhibited the highest density and microhardness, attributed to enhanced particle packing and reduced porosity. The highest fracture toughness was achieved in the Al2O3 matrix reinforced with 1 % MgO/ MWCNTs and 15 % ZrO2, sintered at 1500 degrees C. This improvement is credited to toughening mechanisms such as crack deflection, bridging, and branching facilitated by ZrO2 particles and the strong matrix-reinforcement interface. The incorporation of MgO/MWCNTs improved sintering efficiency due to their thermal properties, enabling uniform heating and enhanced densification.