Mechanical Properties of Transparent Polycrystalline Silicon Nitride
A novel transparent polycrystalline silicon nitride was fabricated by hot-press sintering with MgO and AlN as additives. The mixed powder with 3 wt.% MgO and 9 wt.% AlN was sintered at 1900oC for 1 hour under 30 MPa pressure in a nitrogen gas atmosphere. Transparent polycrystalline silicon nitride was successfully fabricated. The mechanical properties such as density, hardness, young’s modulus, fracture strength and fracture toughness were evaluated. The effect of α/β phase on the mechanical properties of transparent polycrystalline silicon nitride was investigated. The properties were changed depending on the amount of α/β phase. The hardness and Young's modulus increased with increasing the volume fraction of α-phase fraction as a reflection of the higher hardness of α-phase Si3N4. The fracture toughness and fracture strength decreased with decreasing the volume fraction of β-phase Si3N4.
T. Ohji, T. Sekino and K. Niihara
R. J. Sung, T. Kusunose, T. Nakayama, Y. H. Kim, T. Sekino, S. W. Lee, K. Niihara, "Mechanical Properties of Transparent Polycrystalline Silicon Nitride", Key Engineering Materials, Vols. 317-318, pp. 305-308, 2006