In-situ monitoring of ion-beam luminescence of Si-O-C(-H) ceramics under proton-beam irradiation

Narisawa, Masaki*; Koka, Masashi; Takeyama, Akinori; Sugimoto, Masaki; Idesaki, Akira; Sato, Takahiro; Hokazono, Hiroki*; Kawai, Taketoshi*; Iwase, Akihiro*

Journal of the Ceramic Society of Japan, 123(9), p.805 - 808, 2015/09

http://doi.org/10.2109/jcersj2.123.805

Synthesis and properties of ceramic fibers from polycarbosilane/polymethylphenylsiloxane polymer blends

Kita, Kenichiro; Narisawa, Masaki*; Nakahira, Atsushi*; Mabuchi, Hiroshi*; Sugimoto, Masaki; Yoshikawa, Masahito

Journal of Materials Science, 45(13), p.3397 - 3404, 2010/04

https://doi.org/10.1007/s10853-010-4346-2

We synthesized ceramic fibers based on silicon carbide (SiC) from polymer blends of polycarbosilane (PCS) and polymethylphenylsiloxane (PMPhS). PMPhS was compatible with PCS up to 30 mass%. The polymer blend was formed a transparent melt at temperatures higher than 513 K and the softening point was also lowered by adding PMPhS. 15 mass% of PMPhS to PCS was the most suitable condition for obtaining thin fibers with an average diameter of 14.4 m and the ceramic yield of the cured fiber was 85.5% after pyrolysis at 1273 K. In spite of the small diameter, the resulting tensile strength at 1273 K was rather limited at 0.78 GPa. After high temperature pyrolysis at 16731773 K, a porous nanocrystalline SiC fiber with a unique microstructure was obtained with surface area of 70150 m/g.

Formation of continuous pore structures in Si-C-O fibers by adjusting the melt spinning condition of a polycarbosilane - polysiloxane polymer blend

Kita, Kenichiro; Narisawa, Masaki*; Mabuchi, Hiroshi*; Ito, Masayoshi*; Sugimoto, Masaki; Yoshikawa, Masahito

Journal of the American Ceramic Society, 92(6), p.1192 - 1197, 2009/06

https://doi.org/10.1111/j.1551-2916.2009.03053.x

Synthesis of a minute SiC product from polyvinylsilane with radiation curing, 2; Ceramization process of radiation cured polyvinylsilane

Idesaki, Akira; Sugimoto, Masaki; Yoshikawa, Masahito; Tanaka, Shigeru; Narisawa, Masaki*; Okamura, Kiyohito*; Ito, Masayoshi*

Journal of Materials Science, 42(1), p.130 - 135, 2007/01

https://doi.org/10.1007/s10853-006-1041-4

We have synthesized minute SiC products from polyvinylsilane (PVS), which is a liquid organosilicon polymer, with radiation curing. Since there is a close relationship between the properties of obtained SiC products and pyrolysis condition, it is important to investigate the ceramization process of PVS in order to find out the optimum pyrolysis condition. In this paper, the ceramization process of the PVS cured by -ray irradiation at room temperature was investigated by gas analysis, thermogravimetric analysis, density measurement, and so on. It was found that the ceramization of -ray cured PVS starts above 500K, and that drastic organic-inorganic conversion occurs in the temperature range of 700-1100K. According to the results of the changes of mass and density, it was found that the volume shrinkage of PVS during the curing and pyrolysis processes is 80%. The SiC obtained by pyrolysis at 1573K showed the density of 2.50g/cm and microvickers hardness of 31.6GPa.

Minute SiC products synthesized from polyvinylsilane with radiation curing

Idesaki, Akira; Sugimoto, Masaki; Tanaka, Shigeru; Narisawa, Masaki*; Okamura, Kiyohito*; Ito, Masayoshi*

International Symposium in Honor of Professor K. Okamura: Collected Abstracts, 3 Pages, 2003/04

Minute SiC products were synthesized from polyvinylsilane (PVS), which is a liquid organosilicon polymer, with radiation curing. The PVS was injected into molds whose patterns were square and circle with 50m in side or diameter, and 10m in depth. The molds containing the PVS were irradiated by -ray with dose of 3.6MGy at room temperature in vacuum, and heat-treated at 1273K in Ar gas atmosphere. The obtained SiC products had shapes similar to those of the molds, and the sizes of the products were about 30m in side or diameter.

Fine SiC fiber synthesized from organosilicon polymers; Relationship between spinning temperature and melt viscosity of precursor polymers

Idesaki, Akira; Narisawa, Masaki*; Okamura, Kiyohito*; Sugimoto, Masaki; Tanaka, Shigeru; Morita, Yosuke; Seguchi, Tadao; Ito, Masayoshi*

Journal of Materials Science, 36(23), p.5565 - 5569, 2001/12

https://doi.org/10.1023/A:1012549228826

A very fine silicon carbide (SiC) fiber with diameter of 6 m, about a half of that of a commercially available SiC fiber, was synthesized from a polymer blend of polycarbosilane (PCS) and polyvinylsilane (PVS). The fine SiC fiber was obtained by optimizing the composition and the spinning temperature of PCS-PVS polymer blends. In order to determine these optimum conditions, the relationship between temperature and melt viscosities of the polymer blends was investigated. As a result, it was found that the optimum spinning temperature range was within a temperature range where the melt viscosity is 5-10Pas. Moreover, by blending PVS with PCS, the spinning temperature of the polymer blends was lowered, the spinnability of polymer system was improved, and finer polymer fiber was obtained compared with PCS. The optimum content of PVS in the polymer blend was 15-20wt%.

Fine silicon carbide fiber synthesized from a silicon-based polymer blend using radiation curing

Idesaki, Akira; Sugimoto, Masaki; Tanaka, Shigeru; Morita, Yosuke; Narisawa, Masaki*; Okamura, Kiyohito*; Ito, Masayoshi*

High Temperature Ceramic Matrix Composites, p.35 - 40, 2001/00

Silicon carbide (SiC) fiber, which is one of the likeliest candidates as a reinforcement fiber of ceramic matrix composites (CMCs), is synthesized from polycarbosilane (PCS). The diameter of thus SiC fibers is 10-15 m. In order to fabricate CMCs with 3-dimensional complex shapes, it is important to develop a SiC fiber with diameter of less than 10 m, flexibility, and high strength. In order to improve the spinnability of precursor polymer, we have blended polyvinylsilane (PVS), which is a liquid polymer at room temperature, to PCS as a spinning additive. According to relationship between temperature and melt viscosity of the polymer blend, it was found that the polymer can be melt-spun at about 490K, 110K lower than PCS (about 600K), and that the spinnability of the polymer is improved by blending PVS. Fine polymer fiber was obtained from the polymer blend, and finally, very fine SiC fiber with the average diameter of 6 m was synthesized from the PCS-PVS polymer blend.

Use of blended precursors of poly(vinylsilane) in polycarbosilane for silicon carbide fiber synthesis with radiation curing

Narisawa, Masaki*; Idesaki, Akira*; *; *; Sugimoto, Masaki; Seguchi, Tadao; Ito, Masayoshi*

Journal of the American Ceramic Society, 82(4), p.1045 - 1051, 1999/00

https://doi.org/10.1111/j.1151-2916.1999.tb01871.x

no abstracts in English

SiC-based fibers synthesized from hybrid polymer of polycarbosilane and polyvinylsilane

Idesaki, Akira*; Narisawa, Masaki*; *; Sugimoto, Masaki; Morita, Yosuke; Seguchi, Tadao; Ito, Masayoshi*

Key Engineering Materials, 164-165, p.39 - 42, 1999/00

no abstracts in English

Electron spin resonance studies in process of ceramics formation from organosilicon polymers

Narisawa, M.*; Shimoda, M.*; Sugimoto, Masaki*; Okamura, Kiyohito*; Seguchi, Tadao

Advanced Materials '93; Ceramics, Powders, Corrosion and Advanced Processing, p.827 - 830, 1994/00

https://doi.org/10.1016/B978-0-444-81991-8.50200-4

no abstracts in English