Synthesis, Microstructure and Mechanical Properties of Al 2 O 3 /ZrO 2 /CeO 2 Composites with Addition of Nickel and Titania Processed by Conventional Sintering

The aim of the present work is to process densified Al2O3/ZrO2/CeO2 composites, their microstructural characterization and study of their mechanical properties. Alumina ceramic material and alumina based composites are sintered at 1650°C via conventional sintering. Further 3 weight percent of Ni or TiO2 are added in Al2O3/ZrO2/CeO2 compositions and effect on densification and mechanical properties is also studied. Al2O3-40ZrO2-3Ni composite achieved the highest density of 97%. Presence of major phases Al2O3, t-ZrO2, CeO2 peaks are seen in XRD pattern with other intermetallic phases peaks on addition of Ni or TiO2.SEM images revealed the distribution and bonding between grains. EDS confirmed the presence of Al, Zr, Ce, Ni, Ti and O elements in sintered composites. Hardness varied from 9 GPa to 14.35 GPa and the fracture toughness varied from 2.3 to 4.9 MPa.m1/2 with the variation in cermet composition. Al2O3-40ZrO2 composite has the highest hardness of 14.35 GPa and Al2O3-40ZrO2-3Ni composites has the highest fracture toughness of 4.9 MPam1/2. Alumina is not densely sintered which resulted in reduced mechanical properties. Transformation of m-zirconia to t-zirconia crystal structure at high sintering temperature is observed and t-zirconia crystal structure retained on cooling which resulted in toughening of alumina composite. Presence of round pores and pulled out ceria particles visible in ceria added composites which resulted in reduced mechanical properties.