2806 S. Novak et aL. /Journal of the European Ceramic Society 28 (2008)2801-2807 (a)ll For the powder used in this investigation the best results,i.e,a high zeta-potential leading to firm, dense deposits, were obtained for the addition of o5 wt %o of cationic deflocculant CtAB or by adjusting the pH of the suspension to 9 and adding Dolapix. The formation of bubbles due to electrolysis was prevented by using a membrane, in the case of cathodic deposition, and a Cu electrode, in the case of the anodic deposition. The infiltration of an SDOSS-pre-treated Tyrano SA Sic fibre fabric with a negatively charged SiC suspension resulted in dense fibre-based green parts, while the infiltration with suspension of positively charged particles was less effective Powder infiltration prior to the PlP process may considerably by avoiding the several required steps of polymer immersion. Electrophoretic infiltration may also significantly improve the density of SiC/SiC composites, in particular by filling the large voids between the fibre tows This should enable the fabrication of SiC/SiC composites with a close-to-zero porosity, with any remaining pores being closed pores, thus ensuring a hermetic Acknowledgements S Novak would like to thank the royal Society, UK, and the uropean Commission for their financial support of her stay at Imperial College, London, where a part of this work was per- formed. Mr J. Cho(Imperial College London)is acknowledged for experimental assistance The EC (EURATOM-Fusion) and the Agency of Science of the Republic of Slovenia are acknowledged for their financial support of the research on fusion-relevant composites. Dr. A. Ortona, NT Spa, Italy, and Dr B Riccardi (EFDA)are acknowl edged for the supply of the SiC-fibre fabric Special thanks go to Ms. Petra Ursnik for her sustained efforts in the laboratory References U- X27000 10Nm wDk Fig. 7. SEM micrographs of a polished low-angle cross-section of the fabric 1. Muroga, T, Gasparotto, M. and Zinkle, S.J., Overview of materials research for fusion reactors. Fusion Eng. Des., 2002, 13 infiltrated with an alkaline SiC suspension(a-c: different magnifications) 2. Tavassoli, A. A F, Present limits and improvements of structural materials for fusion reactors-a review. J. Nuclear Mater. 2002. 302. 73. 3. Naslain, R, Design, preparation and properties of non-oxide CMCs for individual fibres, demonstrating the success of the develope application in engines and nuclear reactors: an overview. Comp. Sci. Tech- no.,2004,64,155. 4. Riccardi, B. Giancarli, L, Hasegawa, A, Katoh, Y, Kohyama, A, Jones, R. H et al, Issues and advances in SiCf/SiC composites development for 4. Conclusions nead. L.L. and we This study has investigated the influence of surface charges on posites for fusion energy applications. J. Nuclear Mater, 2002, 307-311 the electrophoretic deposition of Sic powder in aqueous suspen 6. Scholz, H. W, Frias Rebelo, A.J. Rickerby, D. G, Krogul, P, Lee, w sions and has demonstrated the usefulness of the electrophoretic E, Evans, J. H. et al, Swelling behaviour and TEM studies of SiCf/SiC infiltration of Sic-fibre fabrics for production of SiC/Sic com omposites after fusion relevant helium implantation. J. Nuclear Mater 1998,258-263,1572. Based on the characteristics of the suspensions and of the bulk 7. Katoh, Y, Kohyama, A Nozawa, T and Sato, composites deposits formed on metallic electrodes, we confirmed that a high through transient eutectic-phase route for fusion 丿. Nuclear while the suspension condi importance for the EPD process, 8. Muroga, T, Gasparotto, M and Zinkle, S.J. Overview of materials research zeta-potential is of outmost ivity plays only a secondary role for fusion reactors. Fusion Eng Des., 2002, 61-62, 13.2806 S. Novak et al. / Journal of the European Ceramic Society 28 (2008) 2801–2807 Fig. 7. SEM micrographs of a polished low-angle cross-section of the fabric infiltrated with an alkaline SiC suspension (a–c: different magnifications). individual fibres, demonstrating the success of the developed EPD technique. 4. Conclusions This study has investigated the influence of surface charges on the electrophoretic deposition of SiC powder in aqueous suspen￾sions and has demonstrated the usefulness of the electrophoretic infiltration of SiC-fibre fabrics for production of SiC/SiC com￾posites. Based on the characteristics of the suspensions and of the bulk deposits formed on metallic electrodes, we confirmed that a high zeta-potential is of outmost importance for the EPD process, while the suspension conductivity plays only a secondary role. For the powder used in this investigation the best results, i.e., a high zeta-potential leading to firm, dense deposits, were obtained for the addition of 0.5 wt.% of cationic deflocculant CTAB or by adjusting the pH of the suspension to 9 and adding Dolapix. The formation of bubbles due to electrolysis was prevented by using a membrane, in the case of cathodic deposition, and a Cu electrode, in the case of the anodic deposition. The infiltration of an SDOSS-pre-treated Tyrano SA SiC- fibre fabric with a negatively charged SiC suspension resulted in dense fibre-based green parts, while the infiltration with a suspension of positively charged particles was less effective. Powder infiltration prior to the PIP process may considerably shorten the densification time of SiC/SiC composite production by avoiding the several required steps of polymer immersion. Electrophoretic infiltration may also significantly improve the density of SiC/SiC composites, in particular by filling the large voids between the fibre tows. This should enable the fabrication of SiC/SiC composites with a close-to-zero porosity, with any remaining pores being closed pores, thus ensuring a hermetic material. Acknowledgements S. Novak would like to thank the Royal Society, UK, and the European Commission for their financial support of her stay at Imperial College, London, where a part of this work was per￾formed. Mr. J. Cho (Imperial College London) is acknowledged for experimental assistance. The EC (EURATOM-Fusion) and the Agency of Science of the Republic of Slovenia are acknowledged for their financial support of the research on fusion-relevant composites. Dr. A. Ortona, NT Spa, Italy, and Dr. B. Riccardi (EFDA) are acknowl￾edged for the supply of the SiC-fibre fabric. Special thanks go to Ms. Petra Ursnik for her sustained efforts in the laboratory ˇ work. References 1. Muroga, T., Gasparotto, M. and Zinkle, S. J., Overview of materials research for fusion reactors. Fusion Eng. Des., 2002, 13. 2. Tavassoli, A. A. F., Present limits and improvements of structural materials for fusion reactors—a review. J. Nuclear Mater., 2002, 302, 73. 3. Naslain, R., Design, preparation and properties of non-oxide CMCs for application in engines and nuclear reactors: an overview. Comp. Sci. Tech￾nol., 2004, 64, 155. 4. Riccardi, B., Giancarli, L., Hasegawa, A., Katoh, Y., Kohyama, A., Jones, R. H. et al., Issues and advances in SiCf/SiC composites development for fusion reactors. J. Nuclear Mater., 2004, 329–333, 56. 5. Snead, L. L. and Weber, W. J., Promise and challenges of SiCf/SiC com￾posites for fusion energy applications. J. Nuclear Mater., 2002, 307–311, 1057. 6. Scholz, H. W., Frias Rebelo, A. J., Rickerby, D. G., Krogul, P., Lee, W. E., Evans, J. H. et al., Swelling behaviour and TEM studies of SiCf/SiC composites after fusion relevant helium implantation. J. Nuclear Mater., 1998, 258–263, 1572. 7. Katoh, Y., Kohyama, A., Nozawa, T. and Sato, M., SiC/SiC composites through transient eutectic-phase route for fusion applications. J. Nuclear Mater., 2004, 329–333, 587. 8. Muroga, T., Gasparotto, M. and Zinkle, S. J., Overview of materials research for fusion reactors. Fusion Eng. Des., 2002, 61–62, 13