COMPOSITES SCIENCE AND TECHNOLOGY ELSEVIER Composites Science and Technology 59(1999)853-859 Fabrication and pressure testing of a gas-turbine component manufactured by a preceramic-polymer- impregnation method Kiyoshi Sato a ,*, Atsushi Tezuka, Osamu Funayama, Takeshi Isoda Yoshiharu Terada. ShinuI Kato Misao Iwata 6 a Corporate Research and Development Laboratory, TONEN Corporation, 1-3-1 Nishi-fsurugaoka, Ohi-lmachi, lruma-gun, Saitama 356-8505, Japan PNoritake Co, Limited, 300 Higashiyama, Miyoshi-cho, Nishikamo-gun, Aichi 470-02, Japan Received I July 1997; received in revised form 24 August 1998; accepted 8 January 1999 Abstract One of the components of the gas-turbine engine, the inner scroll support, was fabricated by a Si-C-O-fiber-reinforced Si-N-C composite of which the matrix was obtained from methylhydrosilazane. The part was shaped by laminating prepreg sheets, con- sisting of Si-C-O fiber cloth and methylhydrosilazane, and cured by using a vacuum-bagging method. Densification of the pro- duct was performed by polymer impregnation and pyrolysis(PIP). The fracture strength and stress/strain behaviour were measured by the use of a hydraulic internal pressurization test Hysteresis during cyclic loading and pseudo-elastic behavior were observed in the composite component. Thus behaviour was similar to that found in mechanical tests of small specimens. The fracture strength of the composite part was estimated to be 180 MPa, which was the same as the tensile strengths of test pieces. 1999 Elsevier Science Ltd. All rights reserved. Keywords: A. Ceramic-matrix composites; Strength test; Polysilazane; Silicon carbide fiber 1. Introduction There are a number of studies on the fabrication of structural parts by the PIP method [11, 12]. Regarding Ceramic-matrix composites which resist heat in an the evaluation of parts made of continuous-fiber-rein oxidising atmosphere have been developed as durable forced ceramics, some thermal exposure tests have been materials for mechanical uses. Many studies have been reported for combustors, but there are few reports of carried out on the fabrication process. Manufacturing a fracture tests [11, 12 fabrication of ceramic-matrix composites industrially 4 The purposes of this work are () to prove the fabri- product to near-net-shape is an important aspects of the because of costs and productivity. Several near-net- fiber-reinforced ceramics for which the matrix was shape processes have been developed; for example, chem- fabricated from methylhydrosilazane by a near-net-shape ical vapor impregnation(CVI), polymer impregnation process and ( ii) to evaluate the fracture strength of the and pyrolysis(PIP), reaction bonding(RB), and direct part by a hydraulic internal pressurization test and metal oxidation [1-4] compare the strength with that of a test piece PIP has considerable merit for shaping Shaping pro- cesses for fiber-reinforced plastics which are used ndustrially can be applied to Plp because both methods 2. Experimental procedure use a resin for the matrix. Many studies have recently been performed on PIP [5-8]. Silazanes synthesized by a 2. 1. M pyridine-adduct method were applied to the PIP method pieces ammufacture of the gas-turbine component and test by the authors [9, 10]. The silazanes have the distinctive features of low viscosity and high yield in converting The gas-turbine component, referred to as an inner ceramics by pyrolyzation. As a result, dense composites scroll support(Fig. 1), was selected because its simple can be fabricated shape makes it easy to fabricate and evaluate. This gas turbine was designed by the Japan Automobile esponding author. Research Institute (JARI) in the 100 kw Automotive 0266-3538/99/S- see front matter C 1999 Elsevier Science Ltd. All rights reserved. PlI:S0266-3538(99)00015Fabrication and pressure testing of a gas-turbine component manufactured by a preceramic-polymer-impregnation method Kiyoshi Satoa,*, Atsushi Tezuka a , Osamu Funayama a , Takeshi Isoda a , Yoshiharu Terada b, Shinji Katob, Misao Iwata b a Corporate Research and Development Laboratory, TONEN Corporation, 1-3-1 Nishi-tsurugaoka, Ohi-machi, Iruma-gun, Saitama 356-8505, Japan bNoritake Co., Limited, 300 Higashiyama, Miyoshi-cho, Nishikamo-gun, Aichi 470-02, Japan Received 1 July 1997; received in revised form 24 August 1998; accepted 8 January 1999 Abstract One of the components of the gas-turbine engine, the inner scroll support, was fabricated by a SiÿCÿO-®ber-reinforced SiÿNÿC composite of which the matrix was obtained from methylhydrosilazane. The part was shaped by laminating prepreg sheets, con￾sisting of SiÿCÿO ®ber cloth and methylhydrosilazane, and cured by using a vacuum-bagging method. Densi®cation of the pro￾duct was performed by polymer impregnation and pyrolysis (PIP). The fracture strength and stress/strain behaviour were measured by the use of a hydraulic internal pressurization test. Hysteresis during cyclic loading and pseudo-elastic behavior were observed in the composite component. Thus behaviour was similar to that found in mechanical tests of small specimens. The fracture strength of the composite part was estimated to be 180 MPa, which was the same as the tensile strengths of test pieces. # 1999 Elsevier Science Ltd. All rights reserved. Keywords: A. Ceramic-matrix composites; Strength test; Polysilazane; Silicon carbide ®ber 1. Introduction Ceramic-matrix composites which resist heat in an oxidising atmosphere have been developed as durable materials for mechanical uses. Many studies have been carried out on the fabrication process. Manufacturing a product to near-net-shape is an important aspects of the fabrication of ceramic-matrix composites industrially because of costs and productivity. Several near-net￾shape processes have been developed; for example, chem￾ical vapor impregnation (CVI), polymer impregnation and pyrolysis (PIP), reaction bonding (RB), and direct metal oxidation [1±4]. PIP has considerable merit for shaping. Shaping pro￾cesses for ®ber-reinforced plastics which are used industrially can be applied to PIP because both methods use a resin for the matrix. Many studies have recently been performed on PIP [5±8]. Silazanes synthesized by a pyridine-adduct method were applied to the PIP method by the authors [9,10]. The silazanes have the distinctive features of low viscosity and high yield in converting ceramics by pyrolyzation. As a result, dense composites can be fabricated. There are a number of studies on the fabrication of structural parts by the PIP method [11,12]. Regarding the evaluation of parts made of continuous-®ber-rein￾forced ceramics, some thermal exposure tests have been reported for combustors, but there are few reports of fracture tests [11,12]. The purposes of this work are (i) to prove the fabri￾cation of a gas-turbine component by using ceramic- ®ber-reinforced ceramics for which the matrix was fabricated from methylhydrosilazane by a near-net-shape process and (ii) to evaluate the fracture strength of the part by a hydraulic internal pressurization test and compare the strength with that of a test piece. 2. Experimental procedure 2.1. Manufacture of the gas-turbine component and test pieces The gas-turbine component, referred to as an inner scroll support (Fig. 1), was selected because its simple shape makes it easy to fabricate and evaluate. This gas turbine was designed by the Japan Automobile Research Institute (JARI) in the 100 kW Automotive Composites Science and Technology 59 (1999) 853±859 0266-3538/99/$ - see front matter # 1999 Elsevier Science Ltd. All rights reserved. PII: S0266-3538(99)00015-9 * Corresponding author