Evolução de microestrutura e propriedades físicas de compósitos Al2O3-TiO2 sob diferentes temperaturas de sinterização parcial

Abstract

This work aims to evaluate the evolution of the microstructure and physical properties of Al2O3-TiO2 (alumina-titania) composites made by uniaxial pressing in the face of its thermal history, under partial sintering conditions between 1100 and 1400 °C. The physical-chemistry processes and phase transformations in the components during heating were studied through thermogravimetric analysis. Phase characterizations were performed by X-ray diffraction using the Rietveld refinement method. The physical properties were evaluated through dimensional analysis and immersion test by the Archimedes principle. Scanning electron microscopy was used to characterize the grains, aided by statistical methods. Partial sintering of the samples in the temperature range was verified and the competing mechanisms of the second stage of sintering, correlating with the physical and microstructural aspects and with the reaction in the solid state, which resulted in the formation of Al2TiO5 (tialite). Finally, it was shown a reduction in the ceramic bulk density from the formation of tialite, despite an increase in the specific gravity, caused by the microcracks and grain bulk volume increases.