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        검색결과 2

        1.
        2003.09 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Carbon/carbon composites are ideal candidates for a number of aerospace applications including structural materials for advanced vehicles, leading edges, structures of re-entry and hypersonic vehicles and propulsion systems. One serious defect for such application of the carbon/carbon composites is their poor oxidation resistance in high temperature oxidizing environments. SiC coating was employed to protect the composites from oxidation. It is mechanically and chemically stable under extreme thermal and oxidative environments, provides good adhesion to the substrate, and offers good thermal shock resistance. The SiC layer on the nozzle machined from the carbon/carbon composites was formed by pack-cementation method. Then, erosion characteristic of SiC coated carbon/carbon nozzle was examined by combustion test using a liquid rocket motor. The erosion rates were measured as function of combustion pressure, ratio of oxygen to fuel, combustion time, density of the composites and geometry of reinforced carbon fibre in the composites. The morphology change of the composites after combustion test was investigated using SEM and erosion mechanism also was discussed.
        4,000원
        2.
        2001.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        The Carbon/Carbon composite was prepared from 3D carbon fiber preform and coal tar pitch as matrix precursor. In order to evaluate of ablative characteristics of the composite, liquid rocket system was employed Kerosene and liquid oxygen was used as propellants, operating at a nominal chamber pressure of 330 psi and a nominal mixture ratio (O/F) of 2.0. The results of an experimental evaluation were that high density composite exhibited high, while low density composites showed low erosion resistance. The erosion rate against heat flux was highly depended on the density of the materials. The morphology of eroded fiber showed differently according to collision angle with heat flux on the composite. The granular matrix which derived from carbonization pressure of 900 bar was more resistance to heat flux than well-developed flow type matrix.
        4,000원