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Effect of starting powder characteristics on density, microstructure and low temperature oxidation behavior of a si3n48w/o y2o3 ceramic
| Content Provider | NASA Technical Reports Server (NTRS) |
|---|---|
| Author | Dutta, S. Schuon, S. |
| Copyright Year | 1980 |
| Description | The densification and oxidation behavior of Si3N4 - 8w/oY2O3 prepared from three commercial starting powders were studied. Bars of SN 402, SN 502, and CP 85/15 were sintered for 3 to 4.5 hours at 1750 C. A second set was hot pressed for 2 hours at 1750 C. The microstructures were studied by transmission electron microscopy and scanning electron microscopy, densities were determined, and the phase compositions were determined by X-ray diffraction. Densification and microstructure were greatly influenced by the starting powder morphology and impurity content. Although SN 402 exhibited the maximum weight lose, the highest sintered and hot pressed densities were obtained with this powder. All powders had both equiaxed and elongated grains. Sintered bars were composed of beta silicon nitride and n-melelite. In contrast, hot pressed bars contained beta silicon nitride, H-phase, and J-phase, but no melelite. Yttria distribution in sintered bars was related to the presence of cation impurities such as Ca, Fe, and Mg. A limited oxidation study at 750 C in air showed no instability in these Si3N4 - 8 w/oY2O3 specimens, regardless of startin powder. |
| File Size | 3214251 |
| Page Count | 23 |
| File Format | |
| Alternate Webpage(s) | http://archive.org/details/NASA_NTRS_Archive_19800018983 |
| Archival Resource Key | ark:/13960/t4zh1fk23 |
| Language | English |
| Publisher Date | 1980-01-01 |
| Access Restriction | Open |
| Subject Keyword | Nonmetallic Materials Scanning Electron Microscopy Chemical Analysis Ceramics Electron Microscopy X Ray Diffraction Hot Pressing Transmission Electron Microscopy Sintering Silicon Nitrides Oxidation Microstructure Yttrium Oxides Low Temperature Ntrs Nasa Technical Reports Server (ntrs) Nasa Technical Reports Server Aerodynamics Aircraft Aerospace Engineering Aerospace Aeronautic Space Science |
| Content Type | Text |
| Resource Type | Article |
