Mechanical and Tribological Properties of MgO/Multiwalled Carbon Nanotube-Reinforced Zirconia-Toughened Alumina Composites Developed through Spark Plasma Sintering and Microwave Sintering

Nanoceramic composites exhibit superior properties over their microcounterparts due to their microstructural differences. However, achieving grain size reduction in these composites through grain suppression is limited. Therefore, the use of nanopowders (both matrix and reinforcement) at the starting level itself and an attempt to further reduce the grain size may yield extraordinary properties. Thus, the present research aims to investigate the tribological and mechanical properties of ZTA nanocomposites reinforced with nano-MgO/MWCNT. The composites were developed separately through spark plasma sintering (SPS) and microwave sintering. The experimental results showed that with increase in the normal load and sliding velocity, the COF decreases, while the wear rate increases. Further, both the COF and wear rate increased with increase in the normal load and sliding velocity beyond a certain point. Moreover, when the normal load is increased beyond 65N, the wear rate of the composites increases rapidly irrespective of the sliding velocities. The addition of MgO increased the hardness through a secondary phase and pinning effect of the composites, while the addition of MWCNTs increased their fracture toughness through crack branching. The wear rate and the COF of the SPS composites were better than their MW-sintered counterparts.