Effect of high temperature heat treatment on the microstructure and mechanical properties of third generation SiC fibers
- PDF / 347,801 Bytes
- 7 Pages / 432 x 648 pts Page_size
- 35 Downloads / 215 Views
Effect of high temperature heat treatment on the microstructure and mechanical properties of third generation SiC fibers Dominique Gosset1, Aurélien Jankowiak2, Thierry Vandenberghe3, Maud Maxel2, Christian Colin4, Nicolas Lochet5 and Laurence Luneville6 1
CEA-Saclay, DMN-SRMA-LA2M, LRC CARMEN, 91191 Gif/Yvette, France
2
CEA-Saclay, DMN-SRMA-LC2M, 91191 Gif/Yvette, France
3
CEA-Saclay, DMN-SRMA-LA2M, 91191 Gif/Yvette, France
4
CEA-Cadarache, DER-SRJH-LEDI, 13108 St Paul-lès-Durance, France
5
CEA-Saclay, DMN-SRMA-LTMEX, 91191 Gif/Yvette, France
6
CEA-Saclay, DM2S-SERMA-LLPR, LRC CARMEN, 91191 Gif/Yvette, France
ABSTRACT SiC fibers (High Nicalon S -HNS and Tyranno SA3 -Ty-SA3) submitted to heat treatments in neutral atmosphere up to 1900°C were studied by X-ray diffraction (XRD) and TEM observations then submitted to tensile tests up to 1800°C. The microstructural changes in both materials were determined by XRD using a modified Hall-Williamson method introducing an anisotropy parameter taking into account the high density of planar defects of the SiC-3C structure. HNS fibers exhibit significant modifications in the CDD size which drastically increases from 24 nm to 70 nm in the range 1600°C to 1800°C and in the microstrains which decrease from 0.0015 to 0.0005 between 1750°C to 1850°C. Concerning the Ty-SA3 fibers, no evolution of CDD size and microstrains has been observed. The mechanical properties of single fibers were investigated after the heat treatments showing decreases in the tensile strength reaching up to 20% for Tyranno SA3 and 50% for High Nicalon S. The Weibull moduli were also significantly affected. These results are correlated to the fiber structural and microstructural evolutions.
INTRODUCTION SiCf/SiCm ceramic matrix composites are considered as promising materials for nuclear reactor applications [1,2].Indeed, the third generation of SiC fibers have significantly improved their
thermo-mechanical properties due to their near stoichiometric composition, high mechanical strength and thermal stability. Furthermore, these fibers contain a small amount of oxygen (
Data Loading...
