Applied Mechanics and Materials Vol. 595

Abstract: He-GTA welding of 10mm thick copper plates by using independent developed welding material - CuTi alloys was investigated. The crystal crack induced by eutectic of Cu and Cu₂O is disappeared completely as the addition of deoxidant element Ti. It can be concluded that the Ti inhibits the formation of Cu₂O and combines with O to generate TiO₂ through the thermal dynamical calculation. As the TiO₂ has the characteristic of high molt point and low density, TiO₂ flows upward to surface of molten pool during welding and forms as weld slag at the weld surface after cooling, then the uniform microstructure without crystal crack is obtained finally. In all GTA welding specimens tested, the failure is located in the heat affected zone and the tensile strength is similar to the base metal.

Abstract: Electroreduction of Fe₂O₃ to Fe in sodium hydroxide solutions has been investigated. It is found that pure iron powder with uniform crystal particles can be obtained by electrolysis of Fe₂O₃ in alkaline solution. The porosity of the iron oxide (Fe₂O₃) pellet and the concentration of NaOH solution have significant influences on the electrolysis process. The deoxidation rate increases with increasing the concentration of NaOH solution, the grain size of iron products decreases with increasing the concentration of NaOH. The optimum NaOH concentration and pressure load used to fabricate Fe₂O₃ pellet are 60 wt% and 6 MPa, respectively. X-ray powder diffraction (XRD) analysis indicates that Fe₃O₄ was produced as the intermediate product during the electroreduction process.

Abstract: Degradation of aqueous bisphenol A (BPA) using photocatalysts of granular iodine doped titanium dioxide (I-doped TiO₂) under various irradiations (365 or 410 nm) was investigated. The degradation effect of aqueous BPA using I-doped TiO₂ photocatalysts (iodine/titanium = 0.5 mole %) were 93 and 100 % under two irradiations of visible and UV light. This result indicated that I-doped TiO₂ photocatalysts of were achieving energy-saving. In addition, the BPA removal rate satisfies pseudo-first-order kinetics and the degradation of BPA was evident after five cycles, indicating the stability and reusability.

Abstract: The montmorillonite (MMT)/multi walled carbon nanotube (MCNTs)/sulfonated polyether ether ketone (sPEEK) nanocomposite membrane were prepared by a method of solution casting for fuel cells application.The MMT and MCNTs were modified with sodium sulfanilateand poly (styrene sulfonic acid) (PSSA), respectively. The proton conductivity of theas-prepared membranes containing 0.5wt.% PSSA grafted MCNTs (PSS-g-MCNTs) and 0.5wt.% sulfonatedmontmorillonite (sMMT) increased by 0.013 Scm⁻¹ compared to the plain sPEEK.The tensile strength and yield strength of which increased by 34.37MPa and 34.20MPa relative to the 1.0 wt.% PSS-g-MCNTs loaded sPEEK, which indicated that PSS-g-MCNTs and sMMT may generate a proton conducting cocontinuous networkwithin the SPEEK matrix.

Abstract: This paper specifically addresses the effect of the sintering temperature curve in manufacturing nickel powder capillary structure (wick) for a loop heat pipe (LHP) with flat evaporator. The sintering temperature curve is composed of three regions: a region of increasing temperature, a region of constant temperature, and a region of decreasing temperature. The most important region is the increasing temperature region, as the rate of temperature increase directly affects the performance of the wick.When the slope of the region of increasing temperature is 0.8 (equivalent to 8 ^OC/min), the structure of the manufactured wick is complete, with the best heat transfer performance result. Experimental resultsshowed that the optimal heat transfer performance is 160W, the minimal total thermal resistance is approximately 0.43^OC/W, and the heat flux is 17W/cm²; the optimal wick manufactured has an effective pore radius of 5.2 μm, a permeability of 5.9×10^-13m², and a porosity of 64%.

Abstract: Active carbon and sodium silicate were produced simultaneously from pyrolyzed rice husk (PRH) by CO₂ activation coupled with NaOH solution boiling. Doehlert matrix and Derringer's desirability function were applied to optimizing the boiling conditions to achieve a large specific surface area, a high silica extraction and low alkali consumption. In terms of this purpose, the optimum condition was determined as boiling CO₂-activated char with 1mol/L NaOH solution at a liquid/solid ratio of 9.7 mL/g. Under this condition, the modulus of the sodium silicate and the specific surface area (SSA) of the active carbon were 2.62 and 897 m²/g, respectively. The values both reached their respective commercial levels. The pretreatment of the PRH with CO₂ activation can markedly increase the SSA of active carbons.

Abstract: Cracking and delamination behavior of small rounded-rectangular gold thin films called “strips” with a thickness less than one micrometer was observed under cyclic and stepwisely-increased trapezoidal tensions. Three strips in different directions were deposited on a polycarbonate plate specimen which was subjected to tensile loading. Straight slit and Vickers indentation were introduced as initial defects on each strip and cracking and delamination which were initiated around the defects were observed. In strips with slit, delamination was observed when introducing the slit. It was suggested that the delamination was caused by the residual stress accumulated during deposition. The growth of delamination was also observed during cyclic tension. In strips with indentation, complex cracking and delamination behavior was observed depending on the strip direction, which seemed to be attributed to the interactive effect of residual stress by deposition and external mechanical loading.

Abstract: The vertical-horizontal rolling in roughing stage of continuous hot strip rolling is a common production technique of controlling slab width effectively. Vertical rolling will induce dog-bone, width loss and fish tail in unsteady deformation zone of slab head and tail. A 3D elastic-plastic FEM model for roughing stage of continuous hot strip rolling was established using ABAQUS/Explicit and research on the influences of those technical parameters such as slab width, slab thickness, reduction of vertical roll and horizontal roll on unsteady deformation of metal was carried out. The research work provides a scientific basis for the optimization of roughing rolling technical schedule.

Abstract: On exposure of high-voltage microsecond pulsed fields the molten salts pass into a non-equilibrium state with disappearance of the characteristic peaks of the Raman spectra and increased electrical conductivity. In the course of the relaxation of nonequilibrium melts their Raman spectra and electrical conductivities are restored to the values and features specific to equilibrium systems in over about 10 minutes.