|Budget Amount *help
¥1,900,000 (Direct Cost : ¥1,900,000)
Fiscal Year 1996 : ¥300,000 (Direct Cost : ¥300,000)
Fiscal Year 1995 : ¥1,600,000 (Direct Cost : ¥1,600,000)
Polymer-derived SiC system fibers are of interest as reinforced fibers for ceramic-matrix composites. The fibers contain substantial amounts of oxygen as well as carbon, beyond the stoichiometric ratio of SiC,and are in an amorphous state. As the fibers are thermodynamically unstable at elevated temperatures (above 1300ﾟC), they have a tendency to crystallize into beta-SiC,generating SiO and CO gases. Such pyrolysis, results in remarkable reduction of fiber strength. However, we have found that the pyrolysis of the fibers are suppressed appreciable by the presence of the surface oxide film. In this research works, the thermal stability of these fibers coated with oxide layrs were investigated in detail. And then, the pyrolytic behavior of these fibers of alumina compact body was investigated. The pyrolysis of these fibers was suppressed by the presence of alumina powders.
Si-Ti-C-O fibers with 13mass% oxygen were heat-treated in a stream of oxygen gas at 1300ﾟC,and the fibers coated with oxide layr of 300-500nm were obtained. Their unidirectional laminated fibers sheets were hot-pressed at 1700ﾟC in Ar, and continuous fiber-bonded ceramic composites were prepared.The composites were formed into several kind of shapes to observe its surface, cross-section and microstructure using SEM and TEM,with the cutting machine bought by GRANT-IN -AID FOR SCIENTIC RESEARCH ((C)(2)). The composites contained of nano-scale structure. The composites were oxidized at 1300ﾟ-1500ﾟC in oxygen atmosphere, and their mass gains were 0.02,0.06 and 0.07% respectively, and the composites are considered to be excellent for oxidation resistance.
We continue to investigate the synthesis and severe environment properties of the developed fiber-bonded ceramic composites in detail.