Advanced Materials Research Vol. 910

Abstract: This article presents a comprehensive investigation in the acoustic characteristics of flame-retardant PET mesh composite fabric and PU foam with the various bulk density of foam and weight ratio of vermiculite. By using impedance tube, absorption coefficients and acoustic impedance of composite material which play an important roles in the estimation of the wave propagation passing through the specific material will be obtained. Results showed that foam with higher bulk density not only increased the material characteristics in the absorption but more importantly, cause the wider band for absorption. With the inclusion of vermiculites, the level of absorption of composite material will obviously increase, especially for the higher frequencies. Instead of 20wt% for vermiculites, the highest absorption coefficient can be found under the 15wt%. On the other hand, acoustic impedance of composite material presented in this article will slowly decrease with frequencies, and the influences of these two parameters are focused on the lower frequency range.

Abstract: Carbon fibers have been coated with a nickelphosphorus (NiP) film using an electroless plating process, with sodium hypophosphite as a reducing agent in an alkaline bath. The morphology, elemental composition and phases in the coating layer of the carbon fibers were investigated by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD), respectively. The results revealed that a continuous, uniform and low-phosphorous nickel coating was deposited on the surface of the carbon fibers for 25 min at pH 8.0, plating bath temperature 90 °C. The as-deposited coatings with approximately 5.8 wt.% phosphorus were found to consist of microcrystalline phases.

Abstract: The response of filament-wound composite tubes subjected to pure bending is studied. The decrease of D/t ratios and increase of winding angles improve the ability to resist buckling failure whereas increasing winding angle generates complex trend in material failure. The ultimate failure mode depends on the interaction of D/t ratio and winding angle. FEM results are in good agreement with experiments.

Abstract: Rheological properties of slick water mixed with CO₂ system are studied,through the large foam fracturing fluid of high temperature and high pressure experiment system,in detail in this paper, based on the principle of tube type rheometer. The influence laws temperature, foam quality, shear rate and pressure have on the rheological characteristics are studied. The fracturing fluid rheological parameters calculation correlations are also obtained, and the foam quality influence on rheological index and rheological coefficient of the slick water mixed with CO₂ system are analyzed.

Abstract: nanozinc oxide (n-ZnO) was synthesized by sol-gel method. The surface of n-ZnO was modified by a silane coupling agent. The modified n-ZnO was then used as rubber vulcanizing activator and nanofiller for BR/SBR blends. The size and morphology of n-ZnO were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The effects of modified n-ZnO on cure characteristics, mechanical properties and thermal conductivity of BR/SBR blends were tested and analyzed. The use of modified n-ZnO resulted in less optimum cure time (t₉₀), higher mechanical properties (anti-abrasion, tear strength, tensile strength, tensile modulus) and thermal conductivity at lower content compared to the conventional micro ZnO(c-ZnO).

Abstract: In the present work, authors have studied the effects of different fiber component on tensile properties of bi-component fiber reinforced composites. The plain preforms were woven. Basalt/polypropylene wrapped yarn and glass fiber/polypropylene wrapped yarns with different component were used as warp and wefts, respectively. The unified molding process was used to form fibre reinforced composites.The tensile properties of composites were tested and analyzed. Results show that the average fracture stress and elastic modulus of composites in weft direction tend to be the best when the volume ratio of glass fiber to polypropylene in the wrapped yarns is 55/45. The maximum fracture stress is 74.79 MPa. The maximum modulus of elasticity is 2.399 GPa.

Abstract: Reductive ammonia leaching method was used to recover Cu and Co from heterogenite. The influences of the reductant quantity, leaching temperature, the concentration ratio of NH₃ to (NH₄)₂SO₄, leaching time and liquid-solid (L/S) ratio on leaching rate of cobalt and copper were investigated. The optimal conditions at which the leaching rate of copper and cobalt were 96.07%, 98.24% respectively and that of Fe, Mg and Al were almost 0 were as follows: time = 5 h, T = 50°C, the amount of ammonia is 1.2 times of theorrtical, C(NH₃):C [(NH₄)₂SO₄] =1:3, L/S ratio = 3:1, and the dosage of Na₂SO₃ is 0.5 times of the heterogenites mass.

Abstract: High volume fraction SiCp/Al composites were milled in ultrasonic longitudinal and torsional vibration high speed milling and high speed milling in this experiment, study on effects of different milling parameters (milling depth ap, feed engagement fz, the milling speed vz) on milling force. The results shows that in the same cutting parameters ,the three milling force of ultrasonic longitudinal and torsional vibration high speed milling are smaller than that of high speed milling, and milling forces of two milling method increase with the add of the milling depth and feed engagement ,but they aren't fold increase. Milling forces of two milling method decrease with the add of the the minlling speed,and the changes become gently when the the minlling speed run up to 170m/min, with the further increase of the milling speed,ultrasonic vibration high speed milling will translate to high speed milling, this is because the torsional vibration is submerged.

Abstract: The influence of impact toughness in vanadium-bearing high strength weathering steels CGHAZ was researched by welding thermal simulation in this paper. The melting and precipitation situation of V, Ti and N in the high strength weathering steel was analyzed in the process of welding thermal simulation according to relative papers. According to the research, TiN in the steel plays a decisive role in CGHAZ on its impact toughness, and give a suggestion about the content of Ti in order to promote the tested steels impact toughness in CGHAZ.

Abstract: A numerical model has been established and solved to describe the dehydration reaction from alcohol to ethylene. The influences of the gas velocity and the temperature of the feeding gas to the process of the reaction were discussed. The results showed that, the influence of the radial diffusion on the reaction characteristics could be ignored while the influence of radial heat conduction to the temperature distribution was significant. The temperature distribution decreased alone the axial direction at first and then increased, that is a lowest point of the temperature could be found. When the velocity of the gas slowed down or the temperature of the feeding gas increased, the conversion of the reactant and the selectivity of the target product could be improved, the distance of the lowest temperature point to the entrance got closer and the outlet temperature became higher.