Preparation and Characterization of Alumina -Strontium Aluminate Based Composite

Abstract

Alumina-Strontium aluminate composites were prepared by mixing of Al2O3 and Sr(NO3)2 and calcination of powder at 1100oC. The calcined powder was compacted and sintered at 1600oC . The calcined powder XRD reveal that about 7% SrO. Al2O3 has formed in-situ in Al2O3. The sintered sample had poor relative density (75% of theoretical). The sintered samples were characterised for apparent porosity, bulk density, hardness, strength and toughness. The hardness of sintered sample was 2.49 GPa, bi-axial flexural strength was 37.3 MPa and Indentation Strength on Bending(ISB) fracture toughness of 1.7 MPam1/2. SEM microstructure of the sintered samples exhibit a porous microstructure. The strontium aluminate particles were seen as bright particles in phase contrast mode. The crack path was also viewed in SEM. It was noted that the cracks either were branched on interacting with strontium aluminate or stopped. This feature indicates the possibility of producing a tough sample if proper density and homogeneous distribution of Strontium aluminate could be achieved.