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Keywords:

Science & Technology, Technology, Nanoscience & Nanotechnology, Materials Science, Multidisciplinary, Metallurgy & Metallurgical Engineering, Science & Technology - Other Topics, Materials Science, sialon ceramic, hot-pressing, impulse excitation technique (IET), high-temperature X-ray diffraction (HTXRD), internal friction (Q(-1)), thermal expansion, NANO-NANO COMPOSITES, SILICON-NITRIDE, CERAMICS, RELAXATION, MATRIX, GROWTH, 0910 Manufacturing Engineering, 0912 Materials Engineering, 0913 Mechanical Engineering, Materials, 4016 Materials engineering, 4017 Mechanical engineering

Abstract:

A powder mixture of α-Si3N4, Al2O3, and TiO2 was hot-pressed using different sintering cycles to search for an optimum in situ formed β-O-sialon-TiN composite. The impulse excitation technique (IET), high-temperature X-ray diffraction (HTXRD), and scanning electron microscopy (SEM) were used to investigate the microstructure. Below the temperature of 1300 °C, the high-temperature internal friction (Q-1) decreases with the increase of sintering temperature, whereas the density of the material increases with the increase of sintering temperature. At a sintering temperature higher than 1850 °C, the ceramic could not be densified and O-sialon was not formed. Also, the mechanical properties of ceramics hot-pressed using different sintering cycles were assessed. The ceramic hot-pressed at 1700 °C for 10 min displays a combination of high hardness and good fracture toughness, due to an optimum combination of β-sialon, O-sialon, and TiN-phases. This paper also evaluated the thermal expansion of β-sialon in the different ceramics hot-pressed using different sintering cycles. © 2006 Elsevier B.V. All rights reserved.