Evaluation of local residual strains in SiC/SiC composite and tungsten joints by synchrotron radiation

Application of SiC/SiC composites and W metal joints to diverters is discussed for development of more attractive systems after DEMO reactors in future. Generally, the residual stress is caused near the interface of metal and ceramics joints by difference in the thermal expansion rate. It is considered that the residual stress lowered the integrity of the interface, so that control of the residual stress is very important to produce the good performance joints. To control the residual stress, knowledge on distribution of the residual stress is required. An X-ray diffraction residual stress measurement is an effective technique for obtaining distribution the residual stress nondestructively. In this work, we investigate the distribution of the residual stress in SiC/SiC composite and W metal sides using synchrotron radiation and discuss the influence of the residual stress on the integrity of the joints. A rectangular-shape-SiC/SiC composite and a W metal plate were prepared and joined by a hot press method at 1873K under compressive stress in Ar atmosphere. X –ray diffraction measurements were carried out at BL22XU in SPring-8. The joints sample was mounted on a stage on a multi-axis diffractometer installed in BL22XU to evaluate the residual strains by a strain-scanning method. X-ray energy in the experiments was 30 and 70 keV. The slit size determining a gauge volume is 30 by 30 m both incident and diffraction sides. The residual strains of SiC/SiC composites and W-metal are introduced from peak shift of (311) and (110), respectively. From the results of the examinations, the drastically stress concentration region was not observed both SiC/SiC and W sides. Probably, it caused by small difference in the thermal expansion between W and SiC. In presentation we will report more detailed information.The 18th International Conference on Fusion Reactor Material