Optimization of microstructure and properties of in situ formed β-O-sialon–TiN composite

• Published in: Materials science & engineering. A, Structural materials : properties, microstructure and processing Vol. 427; no. 1; pp. 195 - 202
• Main Authors: Duan, Ren-Guan, Roebben, Gert, Vleugels, Jozef, Van der Biest, Omer
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.07.2006
• Subjects: High-temperature X-ray diffraction (HTXRD); Hot-pressing; Impulse excitation technique (IET); Internal friction ( Q−1); Sialon ceramic; Thermal expansion; Impulse excitation technique (IET); Thermal expansion; Hot-pressing; Sialon ceramic; Internal friction ( Q −1); High-temperature X-ray diffraction (HTXRD)
• ISSN: 0921-5093; 1873-4936
• DOI: 10.1016/j.msea.2006.04.019

A powder mixture of α-Si 3N 4, Al 2O 3, and TiO 2 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.