Effect of microwave sintering on the structural and densification behavior of sol–gel derived zirconia toughened alumina (ZTA) nanocomposites

Zirconia toughened alumina (ZTA) nanocomposites with different zirconia contents (5–20 mol%) were prepared by the sol–gel method. The prepared composites were sintered at 1300 °C by both conventional and microwave techniques. The crystallinity, average grain size, microstructure and densification of the samples prepared by conventional and microwave sintering methods were compared. X-ray diffraction analysis shows that the microwave sintered samples possess higher tetragonality and also exhibit reduced particle size compared to conventional sintering. HR-SEM surface micrograph reveals that the microwave sintered samples have homogeneous particle size distribution with less degree of porosity. TEM analysis confirms uniform distribution of particles with an average particle size of 20 nm for the microwave sintered sample. SAED pattern reveals that the microwave sintered samples possess improved crystallinity compared to conventional sintered samples. The apparent porosity and density of ZTA nanocomposites measured for different zirconia contents show that the densification of 97% could be achieved for the microwave sintered samples with higher content of zirconium.