Effect of GO doping and sintering temperature on mechanical properties and microstructure of microwave sintered zirconia-toughened alumina (ZTA)

Abstract The influence of the inclusion of graphene oxide (GO) (0, 0.25, 0.5, and 1 wt%) and the sintering temperature (1200 °C, 1300 °C, 1400 °C, and 1500 °C) on the formation of different phases, microstructure, and mechanical properties of microwave-sintered zirconia-toughened alumina (ZTA) was investigated. Phase analysis, density, hardness and fracture toughness, microstructure, and grain size were characterized by X-ray diffraction, Raman spectrum, Archimedes principle, Vickers indentation method, field emission scanning electron microscope (FESEM), and microscopy image analysis software, respectively. X-ray diffraction results of ZTA and GO-doped ZTA showed only Al 2 O 3 , ZrO 2 , GO, and rGO phases, and the results are supported by the Raman spectrum. Density, hardness, and fracture toughness initially increase but subsequently begin to decrease as the wt% of GO increases. In addition, the above properties increase with the sintering temperature for all the samples. ZTA with 0.25 wt % GO ceramic sintered at 1500 °C showed the highest bulk density (4.28 g cm 3 ), relative density (99%), Young’s modulus (398 ± 8 GPa), Vickers hardness (18.75 ± 0.07 GPa), and fracture toughness (5.73 ± 0.12 MPa.m 1/2 ). The microstructure illustrates that low GO content inhibits grain development, while a high GO percentage promotes it. At the same time as the sintering temperature increases, the grain size increases.