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|Development of NITE-SiC/SiC Composite Compact Intermediate Heat Exchanger|
|Keywords: SiC/SiC composites, intermediate heat exchanger, joining|
|Silicon carbide (SiC) can be used in extremely harsh environments due to its excellent mechanical properties and chemical stability even at high temperature. The novel process called Nano-powder Infiltration and Transient Eutectic-phase (NITE) Process has been developed based on the liquid phase sintering process modification. Very dense SiC/SiC composites can be fabricated with excellent gas tightness by NITE process. In the case of High Temperature Gas Reactor, nuclear heat is used in a direct cycle that can be contaminated with fission product such as tritium and the generation plant required a control. With NITE-SiC/SiC composites, it is possible to have low tritium permeability and high temperature strength compact heat exchanger. The objective is to develop the high temperature heat exchanger to provide heat transfer media of above 900 degree C. High temperature gas is a primary target, but due to its chemical stability, liquid metal, water or other coolant is also expected to be used. The scale model was fabricated using NITE-SiC/SiC composites. The machinability and the robust joining method are keys. It was possible to cut screw for NITE-SiC/SiC composites without chipping due to dense feature and excellent fracture toughness. The NITE-SiC/SiC composite plates with 10 cm square and 6 mm thickness were grooved for cooling channels with 5 mm width and 4 mm height. Five NITE-SiC/SiC composite plates including the three plates with cooling channels were joined by hot pressing. For joining technique, the same SiC nano-powder and sintering additive as with NITE processing were used. The scale model was joined with four NITE-SiC/SiC tubes by screw joint and hermetic seal for heat transfer experiments. Present study is the result of gDevelopment on Compact Intermediate Heat Exchanger Using Advanced Composite Materialh entrusted to gKyoto Universityh by the Ministry of Education, Culture, Sports, Science and Technology of Japan (MEXT).|
|Tatsuya Hinoki, Associate Professor
Uji, Kyoto 611-0011,