| Budget Amount *help |
¥7,900,000 (Direct Cost: ¥7,900,000)
Fiscal Year 1990: ¥2,300,000 (Direct Cost: ¥2,300,000)
Fiscal Year 1989: ¥5,600,000 (Direct Cost: ¥5,600,000)
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| Research Abstract |
1. Preparation of the apparatus of pulse CVI process with outer furnace medium scale apparatus for pulse CVI was designed and constructed. In order to shorten the evacuating time to below 1 Torr within 0.8 sec, large pumping system was equipped.
2. Preparating process for preforms the preparating process of two dimensional and three dimensional carbon fiber preforms were studied. Twenty, 40and 60% ethanol solutions of Plyophen (Dainihon Ink., #5900) were compared each other, and the last one which makes the highest ratio of fine pores was selected.
3. The conditions of pulse CVI Mainly, twodimensional C/C preforms with and without 4mum silicon carbide powder were compared. From the results of preliminary experiments, following conditions were selected as standards ; temperature 870-900, concentration of methyltrichlorosilane 4.5-7%, hold time after introduction of gas 0.3-0.6 sec. The preforms with SiC filler were apt to generate microcracks which normally can be seen in C/C composites. Elevating filling ratio of SiC filler is necessary for improvement of the strength of the composites.
4. Three point flexural strength after 10 pulses, the specimens with and without SiC filler showed the strength of 160 and 70 MPa.
5. SEM and EPMA of the cross section T-300 has a considerable clearlance, therefore, infiltration can be done perfectly, on the contrary, M-40 is woven so tight that infiltration is only limited one. The curve of strength vs. number of pulses showed linear property, the refore, the more pulses are considered to improve the strength.
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