Applied Mechanics and Materials Vol. 442

Abstract: By analyzing advantages and disadvantages of the existing energy absorbers, carbon fiber composite and regular hexagon honeycomb structure were chosen as material and topological structure respectively to make a big-bearing, lightweight energy absorber. Preparation method of carbon fiber composite honeycomb energy absorber was studied, which was applied to manufacture some specimens,and it is feasible because of the specimens good consistency and regularity. Quasi-static compression tests of the specimens were carried out, and then the related parameters of energy-absorbing characteristics were calculated. The results show that the carbon fiber composite honeycomb energy absorber has excellent energy-absorbing characteristics.

Abstract: Stability of epoxy-polyurethane (EPU)/aluminum (Al) coatings (the change of coating emissivity during damp heat) was studied after exposure to the damp-heat test for varying lengths of time. We found that the emissivity increased with increasing heating temperature and time in damp heat. In addition, Arrhenius relationship was employed to calculate the lifetime of EPU/Al low infrared emissivity coatings in damp heat. Compared with observation data in damp heat, the calculated results validated the effectiveness of the model predictions, and showed that EPU/Al low infrared emissivity coatings exhibited good resistance to damp heat.

Abstract: The working mechanism of ferrochrome in a new type of copper-based P/ M friction material was studied. The results show that ferrochrome can significantly improve the hardness of the matrix, high temperature resistance, corrosion resistance and other performance of the copper-based friction material, especially the mechanical performance, the friction and wear properties. The affinity of Cr and O is greater than Fe and O. CrO or Cr₂O₃ is formed by Cr which can work as the reduction in the sintering process, thats why the friction coefficient and wear resistance are improved.

Abstract: Microcrystalline silicon thin films prepared by plasma enhanced chemical vapor deposition (PECVD). Effects of deposition power on the microstructure properties of the thin films were investigated by Raman spectrometry, Fourier transform infrared absorption spectroscopy (FTIR) and atomic force microscopy (AFM). With increasing deposition power from 100 W to 900 W, the growth rate increased from 0.75Å/s to 2.96Å/s. The Raman spectrometry measurements showed that the peak of all films is nearby at 514 nm. The FTIR spectroscopic analysis exhibit that with power increasing the intensities of both the (Si-H) _n stretching mode component at 2100cm^-1 and wagging mode component at 620cm^-1 increase. The surface morphology of the films using the AFM showed the surface roughness and voids of the films increase with deposition power increasing.

Abstract: Dyes are usually difficult to be decolorized due to their complex chemical structures. In this work, laccase was purified from the white rot fungus Cerrena unicolor to evaluate its application in dye decolorization. SDS-PAGE analysis showed the purified laccase to be a monomeric protein of 63.7 kDa. The optimum pH for the oxidation of 2,2-azinobis-(3-ethylbenzthiaoline-6-sufonic acid) (ABTS) was 2.2 and the optimum temperature was 50°C. The activity of the purified enzyme was strongly inhibited by sodium azide and partially inhibited by cysteine, dithiothreitol. The K_m values of the purified laccase for the substrate ABTS, syringaldazine and 2,6-dimethoxyphenol were 0.217, 0.306 and 0.199 mmol/L.

Abstract: Strain rate response of polycarbonate was investigated under uniaxial compression at different rates of strain ranging from 0.0001/sec to about 8200/sec and different temperature ranging from 145k to about 423k. A split Hopkinson pressure bar was used to determine the dynamic compressive responses. A pulse-shaping technique was employed in dynamic compression experiment to ensure that valid experimental conditions were satisfied. Results show that, compared with quasi-static behavior, dynamic compression results in significantly higher compressive strengths for polycarbonate materials.

Abstract: Isopropyl alcohol (IPA) is widely used as an additive to enhance the alkaline texturing process of mono-crystalline silicon solar cells currently. However, due to its low boiling point and high volatilization, some negative effects are brought into large scale production especially in stability, cost and environment. In this paper, an IPA-free texturing process was studied by using other additive instead of IPA. The influences of concentration of KOH and additive on etching rate, surface morphology and weighted reflectance were investigated. It is found that the additive has an opposite effect on etching rate and pyramid size compared to KOH. The etching rate and average pyramid size decrease with the concentration of additive increased. The best weight reflectance of 10.8% and lowest average pyramid size of 1.1 um were obtained on mono-crystalline silicon surface by an optimized solution of 1.5 wt% KOH and 1.5 wt% additive at 80oC for 20 minutes. Finally, the effects of KOH and IPA-free additive on the texturing process were also discussed in detail.

Abstract: Zeolite / MC nylon 6 composites were prepared , followed by morphology and properties characterization of composites. The results demonstrated that a large number of pearlitic structures appeared at the interphase between the organic phases and the inorganic phases, indicating that caprolactam had happened anionic in-situ polymerization within the zeolite. The zeolite played a role of molecular rivet in zeolite / MCPA6 composites. The experimental results also showed that the composites performances were largely improved compared with pure MCPA6. When zeolite was 1 Phr, the impact strength of the composite was increased by 58%, temperature of thermal decomposition was rised by 92.9 °C. When zeolite reached 5 Phr, the composite shrinkage rate was reduced by 33%.

Abstract: In this work, a thin-film transmission line (TFTL) employing microstrip line/coplanar waveguide (ML/CPW) on silicon substrate was proposed, and its RF characteristics were investigated. The TFTL employing ML/CPW composite structure exhibited the wavelength shorter than conventional coplanar waveguide and thin-film microstrip line. Concretely, at 10 GHz, the wavelength of conventional coplanar waveguide and thin film waveguide is 10.35 and 7.83 mm, while the wavelength of the TFTL employing ML/CPW composite structure was 6.26 mm, which was 60.5 % of the conventional coplanar waveguide. The TFTL employing ML/CPW composite structure with a length of λ/8 showed the loss less than 1.12 dB up to 30 GHz, which was lower than conventional coplanar waveguide and thin-film microstrip line. Above results indicates that the TFTL employing ML/CPW composite structure is a promising candidate for application to a miniaturization of RF components on silicon RFIC.

Abstract: Essential oils were extracted from biomaterials of root bark, stem bark, twigs, leaves and flowers from Magnolia sieboldii by the means of steam distillation. Their chemical compositions of these essential oils were analyzed by GC-MS method and their flavor properties were evaluated based on the basic media of cold creams. The results showed that the highest yield of essential oils belonged to the essential oil from root bark and the lowest belonged to that from leaves; As to flavor, the parts of leaves and flower are more suitable for exploiting cosmetic products; Twigs, flowers and leaves belonged to the same cluster by Hierarchical cluster analysis on chemical components from these essential oils. The essential oil from leaves should be further exploited due to its good flavor for cosmetic products and a kind of newable natural resources, although this essential oil had lower extraction yeilds.