Effect of TiO2 Addition in Al2O3: Phase Evolution, Densification, Microstructure And Mechanical Properties

Abstract

The thesis describes the effect of TiO2 additionin alumina on phase formation, densification, microstructure and mechanical properties of the composite.The ceramic composite were prepared with Al2O3 and TiO2 powder by solid state mixing route. The Al2O3–TiO2 powders contain 3, 5, 10, 13, 20, and 40 wt% of TiO2. Mixed powders were calcined at 1200oC.Calcinedpowders were uniaxially pressed into cylindrical pellets and rectangular bars, and sintered at 1600oC. X-ray powder diffraction technique was used to study the phase evolution in calcined powder and in sintered specimen. Scanning electron microscope (SEM) was used to find out the particle size and powder morphology of clacined power and microstructure of sintered sample. Flexural strength and Vickers hardness were measured on sintered sample. Calcined powder contains only alumina and titania phase. No intermediate phase was detected. In sintered sample Al2TiO5 phase was detected and its concentration increases with increases in TiO2 content.TiO2 phase was disappeared for high amount of TiO2 (20 and 40wt% addition) addition. It was found that low concentration of TiO2 (upto 10wt %) increases the density of the composite and further increase in TiO2concentration density decreases rapidly. Presence of Al2TiO5phase restricts the grain growth of alumina phase.Flexural strength and Vickers hardness of Al2O3-TiO2-Al2TiO5 composite is dependent on the content of TiO2 and the presence of Al2TiO5 phase.