Microstructural characterization and mechanical properties on Al2O3-TiO2 materials obtained by uniaxial pressing and extrusion

The present investigation compares for the first time the effect of the addition of TiO2 on Al2O3 ceramic materials prepared by uniaxial pressing and extrusion technique. The properties of the disc- and tubular-shaped materials were investigated using different experimental tests, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), Archimedes porosity, linear shrinkage, mechanical performance and scanning electron microscopy (SEM). The XRD analysis revealed the formation of Al2TiO5 phase at 1400 degrees C for discs and tubes, and became more evident when the sintering was performed at 1500 degrees C. The increase of TiO2 loading did not affect the open porosity at a given temperature for the tubular- and disc-shaped samples. The addition of 1 wt % TiO2 led to a remarkable increase of tensile strength for the disc-shaped materials heat treated at all temperatures due to the formation of aluminum titanate. However, a further addition on the TiO2 loading appears to decrease the tensile strength of the disc-shaped samples heat treated at 1400 degrees C and 1500 degrees C. For instance, the flexural strength of the tubes improved with increasing TiO2 loading and sintering temperature from 1300 degrees C to 1500 degrees C. This effect was attributed to the occurrence of a more effective formation of Al2TiO5 on the ceramic tubes. Furthermore, the addition of TiO2 played a key role in controlling the open porosity and the microstructure as confirmed by the SEM images in ceramics obtained by uniaxial pressing and extrusion processing.