Wang Z.,Xian Aerospace Composite Materials Research Institute |
Deng H.-B.,Xian Aerospace Composite Materials Research Institute |
Cui H.,Xian Aerospace Composite Materials Research Institute |
Wang K.-J.,Xian Aerospace Composite Materials Research Institute |
Li J.,Xian Aerospace Composite Materials Research Institute
Guti Huojian Jishu/Journal of Solid Rocket Technology | Year: 2014
Flat needling carbon felts were infiltrated with various inclined angles and gas admission methods, using propylene as carbon source. Density distribution, open porosity, texture of the infiltration samples were characterized by using industrial CT, dielectric soak method and polarized-light microscopy. Under the condition of inclined angle 17° and front gas inlet, density of the infiltrated sample reaches 1.45 g/cm3 after infiltration for 102 h. The density is increasing slightly and the open porosity is decreasing gradually, from the bottom to the top of the samples. Texture of pyrolytic carbon in the samples belongs to smooth laminar mainly. Extinction angle of the samples were measured and the results show that the orientation degree of the texture increases from the bottom to the top of the samples infiltrated with inclined angle of 0° and 17° under back gas inlet. The growth trends of the texture correspond to the design of the materials used for nozzle divergent. ©, 2014, Journal of Solid Rocket Technology. All right reserved.
Lu J.,Northwestern Polytechnical University |
Yang X.,Northwestern Polytechnical University |
Li H.,Northwestern Polytechnical University |
Gao W.,Xian Aerospace Composite Materials Research Institute |
Zhang S.,Northwestern Polytechnical University
Cailiao Yanjiu Xuebao/Chinese Journal of Materials Research | Year: 2012
The compressive fatigue experiment of 2D-C/C composites was made under the stress level of 1000 N, 2000 N and 3000 N, cycling times of 10 4, 10 5 and 3×10 5, the thermal conductivity behavior is tested before and after the fatigue loading, and the effects of compressive fatigue loading conditions on the thermal conductivity behavior of the composites were investigated. The results show that compressive fatigue loading does not change the law about the thermal diffusivity coefficient and specific heat capacity improve with the increasing temperature. However, after the compressive fatigue loading, the thermal conductivity coefficient, thermal diffusivity coefficient of the samples reduce with the increasing of the stress level and cycling times, while the specific heat capacity change little. The decline of the thermal conductivity is related to the fatigue damages generated and accumulated during the compressive fatigue loading after analysis. © right.
Wu X.-J.,Northwestern Polytechnical University |
Qiao S.-R.,Northwestern Polytechnical University |
Cheng W.,Xian Aerospace Composite Materials Research Institute |
Li Y.,Xian Aerospace Composite Materials Research Institute |
And 2 more authors.
Guti Huojian Jishu/Journal of Solid Rocket Technology | Year: 2012
Carbon/carbon composites of pyrocarbon matrix, pyrolytic-resion carbon matrix were treated at 1500°C, 1800°C, 2100°C and 2500°C, respectively. Nano-dimension structure and graphitization degree of treated and untreated composites were characterized by X ray diffraction (XRD) and Raman Spectrum. Micro-pore defects were checked both by scan electronic microscope (SEM) and a mercury instrument. The results show that porosity increases gradually with increasing temperature. The crack type defects don't expand along the tip of crack but width direction in the process of heat treatment. There exists a linear relationship between the porosity and 1-d 002, so an empirical method for evaluation of graphitization degree under different micro porosity was proposed.
Luo J.,Guangxi University of Science and Technology |
Hu Y.,Xian Aerospacemotor Machine Factory |
Yang J.,Xian Aerospace Composite Materials Research Institute |
Hu A.,Henan Polytechnic University
Jisuan Wuli/Chinese Journal of Computational Physics | Year: 2013
With computational fluid dynamics method, effect of embankment inclining angle on aerodynamic characteristics of high speed train under crosswinds is explored. It shows that as inclining angle of embankment is increased, side force coefficient on head train is increased a little and then decreased. Side force coefficient on middle train is gradually decreased. Side force coefficient on rear train is decreased a little and then increased as the angle reaches 47.5°. Negative lifting force coefficient on middle train is increased and lifting force coefficient on rear train is sensitive to inclining angle of embankment. The flow field around train is transformed as the inclining angle of embankment is changed and aerodynamic force or moment is changed consequently.
Cheng G.,Xian Aerospace composite materials research institute
Applied Mechanics and Materials | Year: 2013
A new route for improving the thermal property of phenolic resin was described. Firstly, a soluble preceramic polymer was synthesized by condensation polymerization of zirconium oxychloride, salicyl alcohol and acetylacetone in the presence of triethylamine at room temperature. A modified phenolic resin was then obtained via blending the preceramic polymer and phenolic resin in solution. The preceramic polymer was characterized by FTIR, NMR and GPC. The thermal property of the modified phenolic resin was also investigated by TGA. It was found that the preceramic polymer was composed of Zr-O-Zr as the main chain and the ligands (salicyl alcohol and acetylacetone) as the side chain. It pyrolyzed completely at 600°C and formed ZrO2 in nitrogen atmosphere. The results of TGA indicated that 5 wt% preceramic polymer could increase the thermal decomposition temperature and the char yield of the modified phenolic resin by 18°C and 25%, respectively. Moreover, the preceramic polymer allowed the char formation from phenolic resin at relatively low temperature. © (2013) Trans Tech Publications, Switzerland.