journal of materials ELSEVIER Journal of Nuclear Materials 307-311(2002)1057-1072 www.elsevier.com/locate/jnucma Section 11. Structural ceramics and graphite Promise and challenges of Sic /Sic composites for fusion energy app. lications R.H. Jones a,, L. Giancarli A. Hasegawa, Y. Katoh d ohyama B. Riccardi. LL. Snead w.J. Weber a Pacific Northwest National Laboratory, MS P8-15, P.O. Box 999, Richland, WA 99352, US.A b CEA, Centre d Etudes de saclay, F-9119 Gif sur Yvette cedex, france Tohoku Unirersity, Aoba-ku, Sendai 980-8579, Japan d Institute of Adranced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-00l1, Japan r Oak Ridge National Laboratory, Oak Ridge, TN37831,USA abstract Silicon carbide fiber/silicon carbide matrix composites have been specified in several recent fusion power plant design studies because of their high operating temperature (1000-1100oC)and hence high energy conversion efficiencies Radiation resistance of the B-phase of Sic, excellent high-temperature fracture, creep, corrosion and thermal shock resistance and safety advantages arising from low induced radioactivity and afterheat are all positive attributes favoring the selection of Sicr/SiC composites. With the promise of these materials comes a number of challenges such as their thermal conductivity, radiation stability, gaseous transmutation rates, hermetic behavior and joining technology Re- cent advances have been made in understanding radiation damage in Sic at the fundamental level through MD sim- ulations of displacement cascades. Radiation stability of composites made with the advanced fibers of Nicalon Type s and the UBE Tyranno SA, where no change in strength was observed up to 10 dpa at 800C, in the development of materials with improved thermal conductivity, modeling of thermal conductivity, joining techniques and models for ife-prediction. High transmutation rates of C and Si to form H, He, Mg, and Al continue to be a concern. c 2002 Elsevier science bv all rights reserved 1. Introduction led to their being considered in the TAURO, arIes and dream power plant designs. Sicr/Sic composites offer the promise of a high Challenges for these materials include their thermal temperature fusion reactor design because of the radia- conductivity, radiation stability, gaseous transmuta- tion resistance of the cubic, B-phase SiC matrix, their tion rates, hermetic behavior and joining technology excellent high-temperature fracture, creep, corrosion Their radiation stability is dominated by the differential and thermal shock resistance and safety advantages swelling between the Sic fibers, that are not fully dense arising from their low induced radioactivity and after- or crystalline, carbon interphases and B Sic matrices. heat. Also, developments for other applications, such as Within limits, these materials can be engineered to have aerospace, have driven improvements in material per- select properties; therefore, much of the research in formance that are beneficial to fusion applications. understanding their behavior and improving their per These positive attributes of Sic/Sic composites have formance has been focused on this aspect of their character. An overview of new understanding of the radiation behavior of Sic and SiCr/Sic composites Corresponding author. Tel +1-509 376 4276: fax:+1-509 will be given. This includes fundamentals of radiation 3760418 damage in SiC, advances in new composite materials E-mail address: rh. jones@pnl. gov (R H. Jones). experiments and modeling of thermal conductivity 0022-3115/02/. see front matter e 2002 Elsevier Science B v. All rights reserved PI:S0022-3115(02)00976-5Section 11. Structural ceramics and graphite Promise and challenges of SiCf/SiC composites for fusion energy applications R.H. Jones a,*, L. Giancarli b , A. Hasegawa c , Y. Katoh d , A. Kohyama d , B. Riccardi e , L.L. Snead f , W.J. Weber a a Pacific Northwest National Laboratory, MS P8-15, P.O. Box 999, Richland, WA 99352, USA b CEA, Centre d
Etudes de Saclay, F-9119, Gif sur Yvette cedex, France c Tohoku University, Aoba-ku, Sendai 980-8579, Japan d Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan e ENEA-CR Frascati, via E. Fermi, 27, I00044 Frascati (Roma), Italy f Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA Abstract Silicon carbide fiber/silicon carbide matrix composites have been specified in several recent fusion power plant design studies because of their high operating temperature (1000–1100
C) and hence high energy conversion efficiencies. Radiation resistance of the b-phase of SiC, excellent high-temperature fracture, creep, corrosion and thermal shock resistance and safety advantages arising from low induced radioactivity and afterheat are all positive attributes favoring the selection of SiCf /SiC composites. With the promise of these materials comes a number of challenges such as their thermal conductivity, radiation stability, gaseous transmutation rates, hermetic behavior and joining technology. Re￾cent advances have been made in understanding radiation damage in SiC at the fundamental level through MD sim￾ulations of displacement cascades. Radiation stability of composites made with the advanced fibers of Nicalon Type S and the UBE Tyranno SA, where no change in strength was observed up to 10 dpa at 800
C, in the development of materials with improved thermal conductivity, modeling of thermal conductivity, joining techniques and models for life-prediction. High transmutation rates of C and Si to form H, He, Mg, and Al continue to be a concern. 2002 Elsevier Science B.V. All rights reserved. 1. Introduction SiCf/SiC composites offer the promise of a high￾temperature fusion reactor design because of the radia￾tion resistance of the cubic, b-phase SiC matrix, their excellent high-temperature fracture, creep, corrosion and thermal shock resistance and safety advantages arising from their low induced radioactivity and after￾heat. Also, developments for other applications, such as aerospace, have driven improvements in material per￾formance that are beneficial to fusion applications. These positive attributes of SiCf/SiC composites have led to their being considered in the TAURO, ARIES and DREAM power plant designs. Challenges for these materials include their thermal conductivity, radiation stability, gaseous transmuta￾tion rates, hermetic behavior and joining technology. Their radiation stability is dominated by the differential swelling between the SiC fibers, that are not fully dense or crystalline, carbon interphases and b SiC matrices. Within limits, these materials can be engineered to have select properties; therefore, much of the research in understanding their behavior and improving their per￾formance has been focused on this aspect of their character. An overview of new understanding of the radiation behavior of SiC and SiCf /SiC composites will be given. This includes fundamentals of radiation damage in SiC, advances in new composite materials, experiments and modeling of thermal conductivity, Journal of Nuclear Materials 307–311 (2002) 1057–1072 www.elsevier.com/locate/jnucmat * Corresponding author. Tel.: +1-509 376 4276; fax: +1-509 376 0418. E-mail address: rh.jones@pnl.gov (R.H. Jones). 0022-3115/02/$ - see front matter 2002 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 - 3 1 1 5 ( 0 2 ) 0 0 9 7 6 - 5