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Li J.,AVIC Composite Co. | Shi F.,AVIC Composite Co. | Shi F.,Aerospace Research Institute of Materials And Processing Technology | Lyu J.,AVIC Shenyang Liming Aerospace engine Group Co. | And 2 more authors.
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica

The electric-arc-produced graphene materials were characterized and evaluated by a series of methods such as X-ray photoelectron spectroscopy, Raman spectra, infrared spectroscopy and scanning electron microscope analysis. Results show that the content of C element in graphene is 89.77%, and those of O and N elements are 3.03% and 7.21%. The sample has been identified as multilayer graphene-based Raman spectra G peak and 2D peak position. Adsorption of water in graphene sample is also detected by infrared spectroscopy. The layer number and size of graphene layer structure are observed through microscopic observation. This paper summarized a series of test schemes to characterize graphene,which provides a basis of evaluation for the dissemination and application of graphene in composites. © 2015, BUAA Culture Media Group Ltd.. All right reserved. Source

Tan K.,Northwestern Polytechnical University | Li J.,Northwestern Polytechnical University | Guan Z.,Northwestern Polytechnical University | Yang J.,Northwestern Polytechnical University | And 2 more authors.
Materials and Design

In the present paper, an internal-variable identification approach has been proposed to investigate the dynamic recrystallization (DRX) behavior during hot deformation and corresponding constitutive model has been constructed. Isothermal compression experiments of Ti55511 titanium alloy were conducted for verification. Plastic behavior is determined by dislocation evolution in many cases while deforming. The comparison between saturated and DRX critical dislocation density was made to distinguish the occurrence of dynamic recrystallization/recovery (DRV) during hot deformation. The influence of deformation parameters on DRX behavior was illustrated by dislocation evolution map, validated by the power dissipation efficiency distribution. DRX process during hot deformation of Ti55511 alloy tends to occur under moderate temperatures and low strain rates. In addition, a physical-based Arrhenius constitutive formula has been derived for DRX criticality. The strain-rate sensitivity coefficients during hot deformation were fixed as a constant equal to 1/6 and the deformation activation energy was related to the material's self-diffusion activation. © 2015 Elsevier B.V. Source

Lin G.-Y.,Northeastern University China | Li J.,AVIC Shenyang Liming Aerospace engine Group Co. | Zhao J.,Northeastern University China
Dongbei Daxue Xuebao/Journal of Northeastern University

According to the thoughts of the system theory, taking the driving moment of hoisting system as generalized force, a dynamic model of elastomer and rigid body with many freedom degrees for hoisting system was established using the dynamic theory and Lagrange equation method. The vibration response of hoisting system was calculated based on the matrix iterative method under conditions of locked rotor and vertical boom spreading of bucket rod. The calculated dynamic load coefficient of the high-speed shaft and the hoisting rope is 1.343 and 1.374, respectively. The effects of locked-rotor time and soil stiffness on the dynamic load of hoisting system were analyzed and accordingly the dynamic load coefficients with different soil stiffness were obtained. To reduce dynamic load and ensure the safe functioning of device, the locked-rotor time should not be more than 2.0 s. Source

Gu X.-H.,Shenyang Aerospace University | Liu J.,AVIC Shenyang Liming Aerospace engine Group Co. | Shi J.-H.,Shenyang Aerospace University
Jinshu Rechuli/Heat Treatment of Metals

Influence of quenching and aging temperature on microstructure and mechanical properties of TC4 titanium alloy was investigated through microstructure observation and mechanical property test. The results show that with increasing quenching and aging temperature, the microstructure of the alloy becomes coarse. The strength increases first then decreases with quenching temperature increasing and the plasticity and toughness decrease with quenching temperature increasing. Quenched at the same temperature, the strength decreases and plasticity and toughness increase first and then decrease with aging temperature increasing. Source

Zhang Z.-H.,AVIC Shenyang Liming Aerospace engine Group Co. | Jia Y.-X.,CAS Shenyang Institute of Metal Research

The slab of Ni base single crystal superalloy was fabricated in [001] orientaion by selector technique. This slab was cut into stress rupture samples of which orientaion deviate from [001] within 20°. Under low temperature 750°C and high stress 750 MPa condition, all samples with various misorientation acquire long creep lives and small creep strains. Although their primary creep strains are different, their creep rates in steady creep are equal roughly. Therefore, misorientations within 20° have little influence on whole creep lives. The common deformation feature of samples with different misorientation is formation of numerous stacking faults in γ' phase and entangling large quantities of dislocations in matrix, while their configurations are different in detail. When the misorientation is smaller than 20°, it can only produce a little effect on microstructure evolution and deformation mechanism. Source

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