Preparation and Characterization of Alumina Zirconia Composite Ceramics

Abstract

The composite ceramics between Al2O3 (6 mol%MgO) and ZrO2 (4 mol%Y2O3) were prepared in the Al2O3 (6 mol%MgO added: ZrO2 (4 mol%Y2O3 added) ratios of 20:80, 35:65, 50:50, 65:35 and 80:20. All of samples were sintered using two stage sintering routes with the first temperature (T1) at 1600 °C for 30 min and the second temperature (T2) at 1450 °C for 5 h. The physical properties were characterized from percentage of shrinkage and bulk density. It can be found their tend to decrease with Al2O3 (6 mol%MgO) content increase. XRD patterns were showed combination main phase of rhombohedral of Al2O3 and monoclinic, cubic, tetragonal of ZrO2. Rietveld refinement were used to calculate the percentage of phase composition. All of samples were revealed weight percentage of main composition as m-ZrO2 c-ZrO2 t-ZrO2 and r- Al2O3 in different ratios. It can be found, sample with more content of ZrO2 was showed higher weight percentage of c-ZrO2. The high intensity of Al2O3 peak was appeared from sample with high Al2O3 concentration. SEM micrographs reveal morphology of grain such as grain shape and size of grains. The average grain size value is between 0.81 and 1.07 µm and the size of grain tend to increase with high Al2O3 content. EDX technique were analyzed element compositions of Al2O3 (6 mol%MgO): ZrO2 (4 mol%Y2O3) and EDX spectra were showed wt.% element of Al, Zr, O Y and Mg which is confirmed molecular formular. Moreover, EDX method is identified square shape of Al2O3 (6 mol%MgO) and round shape of ZrO2 (4 mol%Y2O3). The mechanical properties were measured by Vickers and Knoop hardness that were used for calculating the fracture toughness value. It can be found that the optimum mechanical properties were obtained from composite ceramic of 0.35Al2O3 (6 mol%MgO): 0.65ZrO2 (4 mol%Y2O3) which is showed the highest of fracture toughness value about 0.38 GPa.m1/2.