Papers by Author: Masayoshi Itoh

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Authors: Kenichiro Kita, Masaki Narisawa, Hiroshi Mabuchi, Masayoshi Itoh
Abstract: Silicon carbide base ceramic tubes were synthesized from blend polymers of polycarbosilane (PCS) and methylhydrogen silicon oil (H-oil) by polymer precursor method. This precursor method consisted of melt spinning, thermal oxidation curing and pyrolysis processes. Pore structure observed at cross sections of obtained tubes depended on H-oil content, melt-spinning temperature and oxidation curing conditions. At 578K for melt-spinning, however, a considerable amount of H-oil was decomposed during the spinning process. The resulting H-oil contents were usually lower than the starting H-oil contents. In the case of the 578K melt spinning, however, unique single pore structures were often observed in the tubes by adjusting the curing conditions. At 40% of the H-oil content, large pores with thin walls were observed at the cross-section, while such structures were difficult to be controlled. By reducing the melt-spinning temperature to 543K, the starting H-oil contents could be maintained during the spinning process. The cross sections of the tubes often showed multi pores in this case.
Authors: Akira Idesaki, Masaki Sugimoto, Shigeru Tanaka, Masaki Narisawa, Kiyohito Okamura, Masayoshi Itoh
Authors: Masaki Narisawa, Eiji Tanaka, Rokurou Nishimura, Kiyohito Okamura, Masayoshi Itoh, Tomoaki Kamiyama
Authors: Kenichiro Kita, Masaki Narisawa, Hiroshi Mabuchi, Masayoshi Itoh, Masaki Sugimoto, Masahito Yoshikawa
Abstract: Silicon carbide (SiC) based fibers with continuous pore structures were synthesized by the precursor method using a polycarbosilane (PCS) and polymethylhydrosiloxane (PMHS) polymer blends. The pore formation process can be explained by hydrogen gas dissolution in the polymer melt and desaturation process of the dissolved gas during the fiber spinning. We investigated the effect of PMHS additives with different chemical and physical natures on the obtained pore structures, because PMHS decomposition process played a role of hydrogen gas source. The individual polymer melts were characterized by viscosity measurement, gas chromatograph analysis and thermogravimetric (TG) analysis in order to obtain details of pore structure control.
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