Reaction Sintering and Properties of Silicon Oxynitride Densified by Hot Isostatic Pressing |
| |
Authors: | Richard Larker |
| |
Affiliation: | Department of Engineering Materials, LuleåUniversity of Technology, S-951 87 Luleå, Sweden |
| |
Abstract: | Silicon oxynitride ceramics were reaction sintered and fully densified by hot isostatic pressing in the temperature range 1700°C to 1950°C from an equimolar mixture of silicon nitride and silica powders without additives. Conversion to Si2N2O increases steeply from a level around 5% of the crystalline phases at 1700°C to 80% at 1800°C, and increases a few percent further at higher temperatures. α -Si3N4 is the major residual crystalline phase below 1900°C. The hardness level for materials containing 85% Si2N2O is approximately 19 GPa, comparable with the hardness of Si3N4 hot isostatically pressed with 2.5 wt% Y2O3, while the fracture toughness level is around 3.1 MPa. m1/2, being approximately 0.8 MPa.m1/2 lower. The three-point bending strength increased with HIP temperature from approximately 300 to 500 MPa. |
| |
Keywords: | silicon oxynitride sintering hot isostatic pressing X-ray diffraction mechanical properties |
|
|