Non-Cavitational Tensile Creep in Lu-Doped Silicon Nitride

Published

January 1, 2002

Author(s)

F Lofaj, Sheldon M. Wiederhorn, Gabrielle G. Long, B Hockey, P R. Jemian, L Browder, April Andreas

Abstract

The tensile creep behavior of a Lu-based silicon nitride, SN 281, was studied in the temperature range 1400 C to 1550 C with test periods of up to 10 000 h. Strain rates were 3 to 5 orders of magnitude less than those for Yb-based grades of silicon nitride under the same conditions, suggesting a potential for prolonged operation of this material at temperatures up to 1470 C. The stress exponent, n, and the activation energy, Q, for creep are 5.3 2.0 and 757.6 117.0 kJmol-1, respectively. Precise density and ultra small-angle X-ray scattering measurements revealed that, in contrast to other grades of silicon nitride, cavitation does not occur in SN 281. Redistribution of the secondary phases via solution-precipitation combined with grain boundary sliding is discussed as a possible creep mechanism in SN 281. A discussion of the effect of Lu on viscosity indicates that simple replacement of Yb by Lu cannot explain the improvement of creep behavior.

Citation

Journal of European Ceramic Society

Volume

22 No. 14-15

Pub Type

Journals

Keywords

cavity suppression, lutetium, silicon nitride, solution-precipitation, tensile creep

Citation

Lofaj, F. , Wiederhorn, S. , Long, G. , Hockey, B. , Jemian, P. , Browder, L. and Andreas, A. (2002), Non-Cavitational Tensile Creep in Lu-Doped Silicon Nitride, Journal of European Ceramic Society (Accessed December 21, 2024)