A multi-layer coating for carbon-carbon composites with a Si-W outer layer,a SiC barrier layer and a SiC transition layer is prepared by the combination of siliconiza-tion, CVD and liquid reaction method. The effect o...A multi-layer coating for carbon-carbon composites with a Si-W outer layer,a SiC barrier layer and a SiC transition layer is prepared by the combination of siliconiza-tion, CVD and liquid reaction method. The effect of temperature on the oxidation protec-tion life from 1600 to 17OOC is investigated. The thickness of the oxide film on thecoating surface is measured through SEM and EMPA. A concept of critical oxide filmthickness and a critical oxidation protection time is put forward, and, based on it, the re-lation of the critical time with temperature is analyzed. The re8ults show that the relationof the critical oxidation protection time with temperature found by the experiments is fullyidentical with that calcu1ated based on the critical thickness- The physical significance andthe effect factors of the critical oxide film thickness are discussed.展开更多
Different failure modes and morphologies were found in the chemical vapor infiltration(CVI) 2D C/SiC torque tubes with different thickness. To characterize the density and porosity of the ceramic matrix composite(CMC)...Different failure modes and morphologies were found in the chemical vapor infiltration(CVI) 2D C/SiC torque tubes with different thickness. To characterize the density and porosity of the ceramic matrix composite(CMC) torque tube, a CT test was conducted. The archimedes drainage method was used to measure the density and porosity, and by adopting FEM software, the stress distribution and failure strength of the ceramic matrix composite torque tubes were calculated. A universal material test machine was used to implement torsional tests. Different torsional behaviors of CMC torque tubes with two different thicknesses were showed in the stress-strain curves. To analyze the predominant failure factors, SEM was used to observe the failure morphologies and cracks. 5 mm thickness CMC torque tube has reasonable fracture morphologies and a higher maximum shear strength and modulus.展开更多
文摘A multi-layer coating for carbon-carbon composites with a Si-W outer layer,a SiC barrier layer and a SiC transition layer is prepared by the combination of siliconiza-tion, CVD and liquid reaction method. The effect of temperature on the oxidation protec-tion life from 1600 to 17OOC is investigated. The thickness of the oxide film on thecoating surface is measured through SEM and EMPA. A concept of critical oxide filmthickness and a critical oxidation protection time is put forward, and, based on it, the re-lation of the critical time with temperature is analyzed. The re8ults show that the relationof the critical oxidation protection time with temperature found by the experiments is fullyidentical with that calcu1ated based on the critical thickness- The physical significance andthe effect factors of the critical oxide film thickness are discussed.
基金Funded by the Research Fund of the State Key Laboratory of Solidification Processing(NWPU),China(No.135-QP-2015)the Creative Research Foundation of Science and Technology on Thermostructural Composite Materials Laboratory(No.6142911010304)+1 种基金Natural Science Basic Research Plan in Shanxi Province of China(No.2017JM5110)China Postdoctoral Science Foundation(No.2015M570853)
文摘Different failure modes and morphologies were found in the chemical vapor infiltration(CVI) 2D C/SiC torque tubes with different thickness. To characterize the density and porosity of the ceramic matrix composite(CMC) torque tube, a CT test was conducted. The archimedes drainage method was used to measure the density and porosity, and by adopting FEM software, the stress distribution and failure strength of the ceramic matrix composite torque tubes were calculated. A universal material test machine was used to implement torsional tests. Different torsional behaviors of CMC torque tubes with two different thicknesses were showed in the stress-strain curves. To analyze the predominant failure factors, SEM was used to observe the failure morphologies and cracks. 5 mm thickness CMC torque tube has reasonable fracture morphologies and a higher maximum shear strength and modulus.
