S Nogami et aL/ Fusion Engineering and Design 83(2008)1490-1494 107 Matrix. 1000oC Fiber、10009 105 104 103 Depth [nm Depth [nm] 10 28 ≌104 Fig. 4. SIMS spectra as a function of the depth from the oxidized surface for the sic-matrix and Sic-fiber of the Pyc-SiC/SiC composite after oxidation at 1000 C and 1200.C While that of the monolithic pyrolitic graphite was calculated to The parabolic oxidation rate constant(kp) of the monolithic B-Sic 6.04x 10-5kg/m2/s. These values were very similar, therefore, the was 5.20 x 10-8kg/m2/s /2 for 1000C and 2.53 x 10-7kg/m2/s/2 major cause of weight loss in PyC-SiC/SiCat 1000C up to 20 hmight for 1200 C The curves in Fig. 5 are the trend curves calculated using e due to the PyC interface recession by gasification of graphite by those kp value the eqs. (1)and(2). while, the interface region after oxidation at Fig 6 shows the Si-2p XPS spectra for the(a)Sic-matrix and (b) 1200C partly or wholly sealed by reaction phase, which might be SiC-fiber of the Pyc-SiCSic composite after oxidation at 1200.C Sio2 formed on the Sic-matrix and Sic-fiber by the eqs. ( 3)and(4). a function of the depth from the oxidized surface(D). Almost no On the other hand, almost no change was clearly observed for the difference between the Sic-matrix and Sic-fiber was observed. The ML-SiCSiC after oxidation at 1000C and 1200C. 3. 2. Characterization of oxidised layer Fig 4 shows the SIMS spectra as a function of the depth from he oxidized surface for the Sic-matrix and Sic-fiber of the py c SiC/SiC composite after oxidation at 1000Cand 1200 C The depth was measured using a scanning probe microscope(Model P-10, ◇β-siC,1200℃ KLA-Tencor) after sputtering by Cs-ion of the SIMS. Almost no dif- ◆阝-SiC,10o℃ rence between the sic-matrix and sic-fiber was observed. the △Mati100℃ formation of Sio2 layer and reduction and disappearance of Sic ▲Matrⅸx1200℃ vas observed on the surface of the oxidized matrix and fiber of O Fiber,1000℃ he Py C-SiCSiC. Fig. 5 shows the thickness of Sio2 layer evaluated ● Fiber.1200℃C by the SIMS spectra for the monolithic B-SiC and Sic-matrix and Sic-fiber of the Py C-Sic/SiC composite after oxidation at 1000C and 1200C. The Sioz layer thickness was almost the same after 100 h oxidation among the monolithic B-SiC, Sic-matrix and Sic Oxidation Time [h] fiber. The oxidation behavior of the monolithic B-Sic in this work Fig. 5. The thickness of Sioz, layer of monolithic B-Sic and Sic-matrix and Sic-fiber might obey the parabolic rule described in the open literatures [5. of the Pyc-sic Sic after oxidation at 1000.C and 1200.1492 S. Nogami et al. / Fusion Engineering and Design 83 (2008) 1490–1494 Fig. 4. SIMS spectra as a function of the depth from the oxidized surface for the SiC-matrix and SiC-fiber of the PyC-SiC/SiC composite after oxidation at 1000 ◦C and 1200 ◦C. While that of the monolithic pyrolitic graphite was calculated to 6.04 × 10−5 kg/m2/s. These values were very similar, therefore, the major cause of weight loss in PyC-SiC/SiC at 1000 ◦C up to 20 hmight be due to the PyC interface recession by gasification of graphite by the Eqs. (1) and (2). While, the interface region after oxidation at 1200 ◦C partly or wholly sealed by reaction phase, which might be SiO2 formed on the SiC-matrix and SiC-fiber by the Eqs. (3) and (4). On the other hand, almost no change was clearly observed for the ML-SiC/SiC after oxidation at 1000 ◦C and 1200 ◦C. 3.2. Characterization of oxidised layer Fig. 4 shows the SIMS spectra as a function of the depth from the oxidized surface for the SiC-matrix and SiC-fiber of the PyC￾SiC/SiC composite after oxidation at 1000 ◦C and 1200 ◦C. The depth was measured using a scanning probe microscope (Model P-10, KLA-Tencor) after sputtering by Cs-ion of the SIMS. Almost no dif￾ference between the SiC-matrix and SiC-fiber was observed. The formation of SiO2 layer and reduction and disappearance of SiC was observed on the surface of the oxidized matrix and fiber of the PyC-SiC/SiC. Fig. 5 shows the thickness of SiO2 layer evaluated by the SIMS spectra for the monolithic -SiC and SiC-matrix and SiC-fiber of the PyC-SiC/SiC composite after oxidation at 1000 ◦C and 1200 ◦C. The SiO2 layer thickness was almost the same after 100 h oxidation among the monolithic -SiC, SiC-matrix and SiC- fiber. The oxidation behavior of the monolithic -SiC in this work might obey the parabolic rule described in the open literatures [5]. The parabolic oxidation rate constant (kp) of the monolithic -SiC was 5.20 × 10−8 kg/m2/s1/2 for 1000 ◦C and 2.53 × 10−7 kg/m2/s1/2 for 1200 ◦C. The curves in Fig. 5 are the trend curves calculated using those kp value. Fig. 6 shows the Si-2p XPS spectra for the (a) SiC-matrix and (b) SiC-fiber of the PyC-SiC/SiC composite after oxidation at 1200 ◦C as a function of the depth from the oxidized surface (D). Almost no difference between the SiC-matrix and SiC-fiber was observed. The Fig. 5. The thickness of SiO2 layer of monolithic -SiC and SiC-matrix and SiC-fiber of the PyC-SiC/SiC after oxidation at 1000 ◦C and 1200 ◦C.