An investigation on mechanical properties of Alumina-Zirconia-Magnesia spinel composite ceramics fabricated by gel-casting using solution combustion synthesized powder

Addition of spinel (MgAl2O4) to Al2O3-ZrO2 composite inhibits alumina grain growth and produces phase boundaries that leads to formation of a ceramic matrix composite with special mechanical properties such as high temperature superplastic deformation. However, the room temperature mechanical properties of Alumina-zirconia-magnesia spinel composite (AZM) such as fracture toughness were rarely investigated by researchers. In this research the AZM nanocomposite powders were synthesized via the solution combustion method. The dense AZM composite samples were fabricated through gelcasting process. Phase analysis studies were performed on both powder and sintered samples and the effects of spinel and zirconia contents on mechanical properties as well as microstructure of AZM composite samples were investigated. The maximum Vickers hardness (18.83±1.86 GPa) and flexural strength (563.74±23.38 MPa) were achieved in the sample with 10 vol% spinel and 10 vol% zirconia. The sample with 10 vol% spinel and 20 vol% zirconia had the maximum fracture toughness (6.67±0.81 MPa√m).