A. Kurumada

N. Noda

O." Motojima

T. "Oku

Y. Imamura

Y. Kubota

Y. Tomota

National Institute for Fusion Science (NIFS-Repository)

§21. Evaluation of Thermal and Mechanical Properties of Joining Materials between Carbon Material and Oxygen-Free Copper for a Divertor Plate of the LHD Oku, T., Imamura, Y, Kurumada, A., Tomota, Y. (Fac-ulty of Engineering, Ibaraki University), Kubota, Y., Noda, N., Motojima, O. Model specimens with a cooling tube were metallurgically joined a C/C composite with oxygen-free copper by a Ti Dil, which are expected to be applied to a divertor plate of the LHD, were carried out cyclic rapid heating tests. The integrity of the joining parts was evaluated by measuring thermal and mechanical properties using electron beam heating, 3-point bending, continuous indentation and microstructure examination tests. Fig. 1 shows geometIy of a divertor model specimen A £It-type C/C composite (CX-2002U made by Toyo Tanso Co.) was joined metallurgically with oxygen-free copper with a cooling tube using only Ti fuil. The cyclic heating to the specimen was given by using a deflection-type electron beam heating apparatus. T he maximum power was ISkV-2A. A constant heat flux of electron beam was given Dr 10 sec and was stopped fur IS sec due to cyclic rapid heating tests. The heat flux was a range from S to IS MW 1m2. The suntce temperature of the C/C composite and the temperntures of upper and lower parts ofthe joining boundaty were measured by a radiation pyrometer and thennocouples, respectively. The pressure, the speed and the inlet temperature of water coolant were 0.2MPa, 0.7m!s and lSoC, respectively. After heat load tests, test pieces were cut out of the divertor model specimens, 4-point bending tests, continuous indentation tests and SEM observation of the joining part were performed. Fig.2 shows a sUIt1ce temperature and the temperatures of upper and lower parts of the joining boundary of the model specimen at 10 cycles electron beam heating with a heat flux. The sputtering of graphite materials is known to increase abruptly over 1200 °C due to the radiation-enhanced sublimation. In this study, the stufuce temperatures at 10 MW 1m2 heat flux reached to about 1200°C, however, the sumce erosion was not obselVed during 1000 cyclic heat load. On the other hand, the sumce erosion occurred clearly at IS MW 1m2 heat flux and the boundaries between carbon fibers and pyrolytic carbon matrix laminated by the CVD method have been eroded. Fig.3 shows the typical changes of temperatures of the divertor model specimen during 1000 cyclic heat load tests at 10 MW 1m2 heat fiux. The integrity of the joining parts was confirmed because these temperatures were constant in spite of increasing ofthe number of heating cycles. On the other hand, the 4-point bending strength after heat load tests 100 was almost the same as the virgin material of the C/C composite. Consequently, it was concluded that the divertor model specimens with joining parts would be used as a divertor plate Dr the LHD under an operation condition of 10 MW/m2 heat flux. These results were presented at the 2nd IAEA Technical Committee Meeting (Fukuoka, Oct.2S-29, 1999), US -J Workshop on PSI and HHFC (Santa Fe, Nov. 1-4, 1999) and 7th JSME Materials and Processing Conference (Higashihiroshima, Nov.S, 1999). Electron Beam Cooling water ¢7 Fig. 1 GeOmetry of a divertor model specimen. 1500,-------y-----,--- -,-------,2500 2000 1000 P 1500~ ! -~ <D 1000 ~ :J t- 500 C/) 500 10 IS 20 Heat Flux (MW/m 2) Fig.2 Changes in temperatures as a function of heat flux. lQMW/m 2 e~ w ! -()-S<Jrf ... tMII. -G-T_ .• 1 e "" CUUUUU, U U U uu :,uuuuuu:uuu 1=:' ';,"" I ""E ~ 1500 ~--- - -- -- l----- .. -------~--------------~----------·--+------------- ~ i 1000 t~-- --- - -----l----------~---j-.--=-·?- =--- - - - .:--- - ~-:----- - -J' 10 ~ ~ :::: :ll: : : : I '~FEF::ET9': 200 400 600 800 1000 Shot No. Fig.3 Changes in temperatures of the divertor model specimen during 1000 cyclic heat load tests at 10 MW 1m2 heat flux. 

Evaluation of Thermal and Mechanical Properties of Joining Materials between Carbon Material and Oxygen-Free Copper for a Divertor Plate of the LHD

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