Applied Mechanics and Materials Vols. 633-634

Abstract: Carbon nanotubes are very typical nanomaterials, because the electron π of carbon nanotubes is restricted by the quantum size, the energy bands of the electron π are discontiguous and the characteristic of its energy level is divisive. The electron π can absorb the photon and makes transition from low energy level to high energy level, so it has the characteristic of wave-absorption . Based on the theory of quantum mechanics and the atomic structure of carbon nanotubes, the electronic energy bands and absorption spectrum of carbon nanotubes are analyzed in this paper, the results show that carbon nanotubes of different size correspond with absorption spectrum of different wave bands, and the computational results are afforded for the bases of designing wave-absorption materials.

Abstract: Carbon nanotubes (CNTs) have aroused widespread concern for their unique structure and excellent properties in physical, chemical and mechanical. Fileds copper-nickel alloy (Cu-Ni) is a kind of important conductive metal materials that can be widely used in electric, magnetic, catalytic and many other fields as well. The combination of nanocomposites exhibit excellent comprehensive properties which it make it one of the most promising areas at present. This paper shows the preparation of the work and the test result of carbon nanotubes (CNTs) load the nanocopper-nickel alloy (Cu-Ni/CNTs) composite materials that the nanocomposite can be used as an electrode material and fuel cell. In this paper, carbon nanotubes (CNTs) which were acidized by mixed acid are used as templates to prepare nanocopper-nickel alloy (Cu-Ni/CNTs) composite materials. Experiments prove their electrochemical activity is superior to the pure alloy in alkaline solution, and the peak reaches maximum value when alloy is 20 wt%.

Abstract: This work focuses on preparations of CPVC nanofibers by the electrospinning. The effects of the applied voltage, the capillary and collector distance and the extrusion rate on the fiber morphology were analyzed. The morphology of the fiber was examined by scanning electron microscopy. The results indicates that when the applied voltage is 26 KV, the extrusion rate of CPVC is 0.2 ml/h and the the Capillary and Collector Distance is 15 cm, the CPVC nanofiber membrane is optimal.

Abstract: SnO₂ nanowires with a tetragonal structure were synthesized by thermal evaporation of tin grains at 900 °C. The obtained SnO₂ nanowires were doped with Pt and Pd. The morphology, crystal structure, and H₂ sensing properties of undoped, Pt-doped, and Pd-doped SnO₂ nanowires were investigated. SnO₂ nanowires were approximately 30–200 nm in diameter and several tens of micrometers in length. Gas sensors based on undoped, Pt-doped, and Pd-doped SnO₂ nanowires showed a reversible response to H₂ at an operating temperature of RT–300 °C. The response was improved in the order undoped < Pt-doped < Pd-doped SnO₂ nanowire sensors under the same conditions. The highest response upon exposure to 1000 ppm H₂ was 252.9 at 100 °C for Pd-doped SnO₂ nanowire sensor. The results demonstrated that impurity doping improved the sensor response and lowered the operating temperature at which the sensor response was maximized.

Abstract: The test of nano-diamond cathode field emission characteristics was conducted by changing the vacuum, the influence of vacuum change on nano-diamond field emission characteristics was also explored. It was found that under the condition of low vacuum, nano-diamond field emission turn-on field is relatively high, as the vacuum increases, turn-on field decreases gradually, and current density increases. When system vacuum reaches to above 10^-4 Pa level, turn-on field becomes stable, the stable value is 4.5 V/μm; and current density also becomes stable, the stable value is 117 μA/cm²; the luminescence effect of anode which is 200μm distant from the cathode in the vacuum chamber also becomes stable. Results show that 10^-4 Pa is system vacuum limit parameter of stable working of field emission display, the experiment provides a basis to the design and manufacture of nano-diamond field emission display.

Abstract: Quaic-nanotetrapods ZnO nanostructure were fabricated by a simple chemical vapour deposition method. The morphologies, crystalline qualities and optical characteristics of the quaic-nanotetrapods ZnO nanotetrapods were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and photoluminescence (PL) analytic technology, respectively. A piezoelectric nanogenerator based on the ZnO nanotetrapods was fabricated by a simple technique. And the energy harvesting ability is studied by experimental characterization methods and theoretical calculations.

Abstract: In this research, a kind of nonwoven composite used for the absorption of heavy mental ions has been made. The composite was made of two layers of ES thermal bonded nonwovens as the protective layers and the PAN-amidoxime nanofibers which are prepared through the modification of electrospun PAN nanofibers as the interlayer. The composition was achieved by the ultrasonic bonding method. After the composition the PAN nanofibers were modified by grafting the amidoxime group to PAN. The results of FT-IR spectra and FE-SEM indicated that nitrile groups in PAN were partly converted into amidoxime groups and there were no serious cracks on the surface of PAN-amidoxime nanofibers. The results show that the amidoxime groups have been proved to be grafted to the PAN nanofibers with the percent grafting of 81.6%.

Abstract: The structure model of silicon nanograins was built. And then based the modification of the mean free path of phonons according to the size of nanograins, the expression of thermal conductivity in nanograins was obtained according to the phonon kinetic theory. The dependence of the thermal conductivity of silicon nanograins on size was investigated. The results showed that thermal conductivity of nanograins decrease with the reduction of characteristic sizes when the characteristic sizes of nanograins are comparable to or smaller than the phonon mean free path.

Abstract: In this paper, experimental work has been performed to study the influence of temperature and particle volume fraction on the viscosity of aluminum oxide (Al₂O₃)-ethylene glycol nanofluids. Nanofluids with particle volume fraction at 1%-4% were examined. Viscosity experiments were carried out at 20°C-60°C. The results show that the viscosity increases as the particle volume fraction increasing, but decreases with an increasing of temperature. It is found that the relative viscosity is independent of temperature for a particular particle concentration, and independent of particle volume fraction at a certain temperature. Furthermore, formula of Chen was verified appropriately, and a correlation was proposed for computing relative viscosity.