High Temperature Creep of Ceramics.
Abstract
Tensile and compression creep measurements were made on yttria-stabilized zirconia (YSZ), hot-pressed silicon nitride and silicon materials, in atmospheres including air, nitrogen, argon and vacuum. For relatively fine-grained YSZ (below 40 microns), the 1.5 power of the applied stress at low stresses and with the stress cubed at high stresses, but results for coarse grained specimens can generally be fitted by the cube dependence. Creep activation energies for YSZ are found to be 128 kcal/mole independent of yttria content, impurity level, grain size and porosity distribution. For the silicon compounds, at least two different creep mechanisms are operative in the range of temperatures and stresses employed in this study. A grain boundary sliding mechanism, characterized by a stress dependence of two and an activation energy of 168 kcal/mole, appears to be operative for hot-pressed silicon nitride; but a viscous creep mechanism predominates for some SiAlON materials, where a linear stress dependence and an activation energy of 94 kcal/mole have been measured. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1976
- Accession Number
- ADA031766
Entities
People
- Martin S. Seltzer
Organizations
- Battelle Memorial Institute