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Other TitleImprovement in oxidation resistance of C/C-composites with CVD-SiC coating
Author(jpn)小野 文衛; 竹腰 正雄; 植田 修一
Author(eng)Ono, Fumiei; Takegoshi, Masao; Ueda, Shuichi
Author Affiliation(jpn)宇宙航空研究開発機構 総合技術研究本部 角田宇宙センター; 宇宙航空研究開発機構 総合技術研究本部 角田宇宙センター; 宇宙航空研究開発機構 総合技術研究本部 角田宇宙センター
Author Affiliation(eng)Japan Aerospace Exploration Agency Kakuda Space Center, Institute of Aerospace Technology; Japan Aerospace Exploration Agency Kakuda Space Center, Institute of Aerospace Technology; Japan Aerospace Exploration Agency Kakuda Space Center, Institute of Aerospace Technology
Issue Date2006-09-29
PublisherJapan Aerospace Exploration Agency (JAXA)
Publication date2006-09-29
AbstractSilicon carbide formed by chemical vapor deposition (CVD-SiC) is widely used as an anti-oxidation coating on carbon/carbon (C/C) composites and graphite. The oxidation resistance of C/C composites with SiC coating is insufficient due to the generation of cracks or pinholes in the coating. In this study, the mechanism of excessive oxidation associated with coating damage was estimated from a chemical equilibrium calculation, and results of the calculation were verified through heating tests. In addition, test pieces intended to have improved of oxidation resistance were made and these confirmed the effect of processing after heating in air at 1,773-1,973 K. From the results of the chemical equilibrium calculation, it was expected that excessive oxidation of the SiC coating would occur in the 1,800-1,900 K region. This expectation was confirmed by the heating test at 1,773 K-1,973 K. For adequate durability, the upper limit of use for C/C composites with CVD-SiC coating should be below 1,773 K. Test pieces with intermediate layers under the CVD-SiC layer were made and evaluated at 1,973 K. For crack suppression in the CVD-SiC layer, test pieces treated by putting an intermediate layer between the CVD-SiC layer and C/C composites, or treated by weaving SiC fiber into the surface of the C/C composites, were made and evaluated in 1,973 K. Although crack generation could not be completely prevented by these methods, the mass loss of the test pieces decreased by 73-78 percent over 10- and 20-hour heating periods. The improvement in durability was brought about by the continuation of the silica sealing effect for a prolonged period. The intermediate layer and the woven SiC fiber enhanced the generation of silica. A new processing method using silica formed from perhydropolysilazane (PHPS) polymer was used to seal cracks in the CVD-SiC coating. 2D-C/C composite test pieces processed with this method were heated in air at 1,773 K, and lost approximately 30 percent less mass.
DescriptionJAXA Research and Development Report
KeywordsC/C-composite; oxidation resistance; silicon carbide; chemical equilibrium; chemical vapor deposition; graphite; perhydropolysilazane; thermal expansion; oxidation; C/C複合材; 耐酸化性; 炭化ケイ素; 化学平衡; 化学蒸着; 黒鉛; ペルヒドロポリシラザン; 熱膨張; 酸化
Document TypeTechnical Report
JAXA Category研究開発報告
Report NoJAXA-RR-06-003

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