An, Linan ; Riedel, Ralf ; Konetschny, Christoph ; Kleebe, Hans-Joachim ; Raj, Rishi (1998)
Newtonian Viscosity of Amorphous Silicon Carbonitride at High Temperature.
In: Journal of the American Ceramic Society, 81 (5)
doi: 10.1111/j.1151-2916.1998.tb02489.x
Article
Abstract
The creep viscosity of chemical-precursor-derived silicon carbonitride (SiCN), which is known to remain predominantly amorphous at temperatures below 1400°C, was measured in the temperature range 1090-1280°C. Experiments were done in uniaxial compression at constant loads in pure nitrogen atmosphere. The creep behavior exhibited three stages. In stage I the strain rate decreased rapidly with time and deformation was accompanied by densification. In stage II the samples exhibited a steady-state creep rate. In stage III, which commenced after long-term deformation, creep gradually declined to rates that were below the sensitivity of our apparatus. The relative density of the specimens during stage II and stage III remained constant at ≅2.3 g/cm3. The shear viscosity in stage II was nearly Newtonian and was measured to be 1.3 × 1013-5.0 1013 Pa·s at 1280°C, which is approximately 103 times the value for fused silica. The creep-hardened as well as uncrept specimens contained silicon nitride crystallites. The volume fraction of these crystals was variable but always less than 5%. Such a small volume fraction of crystals does not explain the dramatic creep-hardening behavior in stage III, even if it is assumed that the crystals formed during creep deformation in stage II.
| Item Type: | Article |
|---|---|
| Erschienen: | 1998 |
| Creators: | An, Linan ; Riedel, Ralf ; Konetschny, Christoph ; Kleebe, Hans-Joachim ; Raj, Rishi |
| Type of entry: | Bibliographie |
| Title: | Newtonian Viscosity of Amorphous Silicon Carbonitride at High Temperature |
| Language: | English |
| Date: | May 1998 |
| Publisher: | Wiley |
| Journal or Publication Title: | Journal of the American Ceramic Society |
| Volume of the journal: | 81 |
| Issue Number: | 5 |
| DOI: | 10.1111/j.1151-2916.1998.tb02489.x |
| Abstract: | The creep viscosity of chemical-precursor-derived silicon carbonitride (SiCN), which is known to remain predominantly amorphous at temperatures below 1400°C, was measured in the temperature range 1090-1280°C. Experiments were done in uniaxial compression at constant loads in pure nitrogen atmosphere. The creep behavior exhibited three stages. In stage I the strain rate decreased rapidly with time and deformation was accompanied by densification. In stage II the samples exhibited a steady-state creep rate. In stage III, which commenced after long-term deformation, creep gradually declined to rates that were below the sensitivity of our apparatus. The relative density of the specimens during stage II and stage III remained constant at ≅2.3 g/cm3. The shear viscosity in stage II was nearly Newtonian and was measured to be 1.3 × 1013-5.0 1013 Pa·s at 1280°C, which is approximately 103 times the value for fused silica. The creep-hardened as well as uncrept specimens contained silicon nitride crystallites. The volume fraction of these crystals was variable but always less than 5%. Such a small volume fraction of crystals does not explain the dramatic creep-hardening behavior in stage III, even if it is assumed that the crystals formed during creep deformation in stage II. |
| Divisions: | 11 Department of Materials and Earth Sciences 11 Department of Materials and Earth Sciences > Earth Science 11 Department of Materials and Earth Sciences > Earth Science > Geo-Material-Science 11 Department of Materials and Earth Sciences > Material Science 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids |
| Date Deposited: | 15 Nov 2012 09:14 |
| Last Modified: | 12 Aug 2021 11:52 |
| PPN: | |
| Funders: | Supported by the North Atlantic Treaty Organization, and partially by a grant from the Division of Materials Research at the National Science Foundation (DMR-9796100). |
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