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High temperature creep behaviour of ceramics
- Source :
- Journal of the European Ceramic Society. 17:1647-1654
- Publication Year :
- 1997
- Publisher :
- Elsevier BV, 1997.
-
Abstract
- The improvement in high temperature mechanical properties of silicon nitride ceramics has been explored by fabrication of a β′-Si 3 N 4 α-YSiAlON ceramic densified, without additives and without HIP treatment, by sintering of a mixture of α-Si3N4 and α- YSiAlON powders under a nitrogen pressure of 5 MPa. The high temperature creep behaviour was investigated in the ranges 100–400 MPa and 1280–1400 ° C by compressive tests. The creep performances were very impressive. The activation energy (Q = 770 kJ/mol) and the stress exponent (n = 1) are consistent with a deformation mechanism resulting from grain boundary sliding accommodated by volume diffusion. Microstructure was not affected by the deformation conditions, in particular no cavity formation was observed after creep at 1400 °C and 300 MPa. This behaviour is related to the probable absence of a thick boundary film which may result from crystallization during cooling of small glass pockets and from internal stresses caused by the volume change of crystallizing pockets.
Details
- ISSN :
- 09552219
- Volume :
- 17
- Database :
- OpenAIRE
- Journal :
- Journal of the European Ceramic Society
- Accession number :
- edsair.doi...........50d62ca517fe91ea9a055c377aba90e8