K. Sato et al./ Composites Science and Technology 59(1999)853-859 fiber-reinforced Si-N-C composite whose matrix was obtained from methylhydrosilazane. The fracture strength and the stress/ strain behaviour were measured by using a hydraulic internal pressurization test. Hys- teresis during cyclic loading and pseudo-elastic behavior were observed in the composite part, and similar beha vior was found during mechanical tests of small speci mens. The accuracy of the calculated strength of the part was relatively low. Nevertheless, the composite part showed the same level strength, 180 MPa, as the test cno Fig. 13. Fracture surface of inner scroll support This work was conducted by the Petroleum Energ Center with a financial support from the Ministry of the elastic moduli were 122 and 114 GPa, respectively. International Trade and Industry. The authors The fracture strength of the inner scroll support was 180 acknowledge Mr. Takao Izumi at the Japan Auto- MPa. The value was higher than the that of the 45 off mobile Research Institute for enforcement of the axis test piece, which had a similar fiber structure. The hydraulic internal pressurization test differences in porosity and fiber content between the part and the test pieces were small (Table 2). Tow pos- sible reasons for the strength difference between the test References coupons and the part are: (i) the detailed difference in the fiber structures (ii) error in the calculated stress on [] Naslain R, Langlais F Mater Sci Res 1986: 20: 14 ne part because the anisotropic elasticity of the compo- [2 Walker BE, Rice RE, Becher PE, Bender BA, Coblenz ws site was disregarded. By observing the fiber structure of eram Bull 1983: 62: 916 the inner scroll support, the extension of the direction 3 Corbin ND, Rossetti GA, Hartline SD. Ceram Eng Sci Proc 1986;7:958 close to the latitudinal direction was found, i. e. the angle (Newkirk MS, Lesher HD, White DR, Kennedy CR, Urgha between the fiber tows and the hoop direction changed Aw, Clarr TD. Ceram Eng Sci Proc 1987: 18: 879. from 45 to 40(Fig. 11). This extension was caused by Schwab ST, Page RA, Davidson DL, Graef RC, Tredway WK stacking the prepreg sheets onto the curved surface of eram Eng Sci Proc 1995: 16: 743. the shaping jig. The latitudinal orientation of the fiber [6 Miller DV, Pommel DL, Schiroky GH. Ceram Eng Sci Proc 1997;18:409 caused the increase in the fracture strength of the part [7 Inerrante Lv, Jacobs JM, Sherwood W, Whitmarsh Cw. Key The fractured composite part is shown in Fig. 12 and Eng mater I997;127-131:271 the fracture surface is shown in Fig. 13. If a monolithic [8 Duran A, Aparicio M, Rebstock K, Vogel WD. Key Eng Mater ceramic part is broken by the hydraulic internal pres- 97:127-131:287 9 Sato K, Suzuki T, Funayama O, Isoda T. Ceram Eng Sci Proc surization test, the test body is separated into more than 1992:13:614 2 pieces. The absence of separation after the test is a [10] Morozumi H, Sato K, Tezuka A, Kaya H, Isoda T.Ceramic distinctive feature of parts made with continuous fiber International 1997- 23: 179 reinforced ceramics. On the fractured surface, many [I Fohey WR, Battison JM, Nielsen TA, Hastings S Ceram Eng Sci long pulled-out fibers were observed, as also seen on the [12] Kochendorfer R, Krenkel W. High-temperature ceramic-matrix test pieces omposites I. Ceramic Transactions 1995: 57: 13 [ Kaya H, Izumi T. Proceeding of ASME TRUBO EXPO 96, Birmingham in UK, 1996. June 10-13. 96-GT-348 4. Conclusion [14 Funayama O, Kato T, Tashiro Y, Isoda T. J Am Ceram Soc 1993:76:717 [5 Aubard x, Lamon J, Allix O. J Am Ceram Soc 1994: 77: 218. One of the components of the gas-turbine, the inner [16] Mizuno M, Zuh S, Nagano Y, Sakaida Y,Kagawa Y,Watanabe scroll support, was successfully fabricated by a Si-C-O M. J Am Ceram Soc 1996: 7913: 3065.the elastic moduli were 122 and 114 GPa, respectively. The fracture strength of the inner scroll support was 180 MPa. The value was higher than the that of the 45 o€ axis test piece, which had a similar ®ber structure. The di€erences in porosity and ®ber content between the part and the test pieces were small (Table 2). Tow pos￾sible reasons for the strength di€erence between the test coupons and the part are: (i) the detailed di€erence in the ®ber structures (ii) error in the calculated stress on the part because the anisotropic elasticity of the compo￾site was disregarded. By observing the ®ber structure of the inner scroll support, the extension of the direction close to the latitudinal direction was found, i.e. the angle between the ®ber tows and the hoop direction changed from 45 to 40 (Fig. 11). This extension was caused by stacking the prepreg sheets onto the curved surface of the shaping jig. The latitudinal orientation of the ®ber caused the increase in the fracture strength of the part. The fractured composite part is shown in Fig. 12 and the fracture surface is shown in Fig. 13. If a monolithic ceramic part is broken by the hydraulic internal pres￾surization test, the test body is separated into more than 2 pieces. The absence of separation after the test is a distinctive feature of parts made with continuous ®ber￾reinforced ceramics. On the fractured surface, many long pulled-out ®bers were observed, as also seen on the test pieces. 4. Conclusion One of the components of the gas-turbine, the inner scroll support, was successfully fabricated by a SiÿCÿO ®ber-reinforced SiÿNÿC composite whose matrix was obtained from methylhydrosilazane. The fracture strength and the stress/strain behaviour were measured by using a hydraulic internal pressurization test. Hys￾teresis during cyclic loading and pseudo-elastic behavior were observed in the composite part, and similar beha￾vior was found during mechanical tests of small speci￾mens. The accuracy of the calculated strength of the part was relatively low. Nevertheless, the composite part showed the same level strength, 180 MPa, as the test pieces. Acknowledgements This work was conducted by the Petroleum Energy Center with a ®nancial support from the Ministry of International Trade and Industry. The authors acknowledge Mr. Takao Izumi at the Japan Auto￾mobile Research Institute for enforcement of the hydraulic internal pressurization test. References [1] Naslain R, Langlais F. Mater Sci Res 1986;20:145. [2] Walker BE, Rice RE, Becher PE, Bender BA, Coblenz WS. Ceram Bull 1983;62:916. [3] Corbin ND, Rossetti GA, Hartline SD. Ceram Eng Sci Proc 1986;7:958. [4] Newkirk MS, Lesher HD, White DR, Kennedy CR, Urqhart AW, Clarr TD. Ceram Eng Sci Proc 1987;18:879. [5] Schwab ST, Page RA, Davidson DL, Graef RC, Tredway WK. Ceram Eng Sci Proc 1995;16:743. [6] Miller DV, Pommell DL, Schiroky GH. Ceram Eng Sci Proc 1997;18:409. [7] Inerrante LV, Jacobs JM, Sherwood W, Whitmarsh CW. Key Eng Mater 1997;127±131:271. [8] Duran A, Aparicio M, Rebstock K, Vogel WD. Key Eng Mater 1997;127±131:287. [9] Sato K, Suzuki T, Funayama O, Isoda T. Ceram Eng Sci Proc 1992;13:614. [10] Morozumi H, Sato K, Tezuka A, Kaya H, Isoda T. Ceramic International 1997;23:179. [11] Fohey WR, Battison JM, Nielsen TA, Hastings S. Ceram Eng Sci Proc 1995;16:459. [12] Kochendorfer R, Krenkel W. High-temperature ceramic-matrix composites I, Ceramic Transactions 1995;57:13. [13] Kaya H, Izumi T. Proceeding of ASME TRUBO EXPO `96, Birmingham in UK, 1996, June 10±13, 96-GT-348. [14] Funayama O, Kato T, Tashiro Y, Isoda T. J Am Ceram Soc 1993;76:717. [15] Aubard X, Lamon J, Allix O. J Am Ceram Soc 1994;77:218. [16] Mizuno M, Zuh S, Nagano Y, Sakaida Y, Kagawa Y, Watanabe M. J Am Ceram Soc 1996;7913:3065. Fig. 13. Fracture surface of inner scroll support. K. Sato et al. / Composites Science and Technology 59 (1999) 853±859 859