Advanced Materials Research Vols. 287-290

Abstract: The performance of half-cell for anode supported Solid Oxide Fuel Cells (SOFCs) is necessary to wide use of SOFCs. This work is to study the reduction degree of anode and the residual stress changes that occur during hydrogen reduction on the different temperatures and in different times. The porosity of the specimens with oxidation is less than that of the reduction one. There is no Ni phase in the sample before hydrogen reduction. After hydrogen reduction on 1000°C for 6 hours, there is no NiO phase in the sample. It reveals the NiO has been reduced into Ni completely. We also investigate residual stresses in the electrolyte layer using X-ray diffraction. The residual stress value of electrolyte is about -844.1MPa before reduction. After hydrogen reduction on 800°C for 9 hours, the residual stress is decreased to -474.8MPa. So the reduction temperature can choose as 600°C and the reduction time can choose as 9 hours.

Abstract: A series of cross-linked proton exchange membranes with the ion exchange capacities (IECs) of 0.70 - 1.52 meq/g have been prepared via the reaction of the anhydride-terminated sulfonated polyimide oligomers (SPI-3, SPI-5 and SPI-7, here the figure refers to the averaged block length) and the polybenzimidazole with pendant amino groups (H₂N-PBI) in dimethylsulfoxide (DMSO) during the membrane cast process. The prepared cross-linked membranes showed high tensile strength (55 - 80 MPa) and good water stability (> 2 months in deionized water at 100 °C). Fenton’s test revealed that all the cross-linked membranes displayed significantly better radical oxidative stability than the corresponding pure SPIs. This is attributed to the presence of the highly oxidative-stable PBI component in the cross-linked membranes. The proton conductivities of the cross-linked membranes increased with increasing temperature and relative humidity. The cross-linked membrane prepared from the longest oligomer (SPI-7) displayed the highest proton conductivity which is comparable to that of Nafion 117.

Abstract: The influence of cold rolled deformation on the electrochemical properties of Al anode materials in 4 mol L^-1 KOH solutions was investigated by electrochemical tests and metallographic observation. The results indicate that cold rolled process could improve the electrochemical performance of Al anode alloys compared with that of as-cast alloy. With the increase of deformation, the self-corrosion rate and hydrogen evolution rate of Al anode decreased firstly and then increased slightly. The alloy with 80% cold rolling reduction had the lower self-corrosion and hydrogen evolution rate, longer discharge time and good electrochemical performance.

Abstract: La_0.75Mg_0.25Ni_3.5(TiNi₃)_0.1 alloys were prepared by induction melting followed by annealing treatment at 1173Kand 1h,2h,5h,12h,respectively. Alloys structure and electrochemical properties have been studied systematically by X-ray diffraction(XRD) with the Rietveld methold , Electron probe micro-analyzer (EPMA)and electrochemical experiments. Alloys structure analyses showed that all of the alloys mainly consisted of complex phases such as LaNi5 phase (CaCu₅-type,SG: P6/mmm), (La ,Mg)2Ni7 phase (Ce₂Ni₇-type, SG: P6₃/mmc)and (La,Mg)2Ni7 phase(Gd₂Co₇-type,SG: R-3m). Annealed treatment was benefited to the formation of (La ,Mg)2Ni7 phase. Annealed time was imprtant for the alloys microstructure, for the alloys with annealed for 1 hour,the microstructure between main phase and TiNi₃ phase was three-dimensional network,with the annealed time incresed,the TiNi₃ phase became reunite. The microstructure of three-dimensional network was useful for the electrochemical cycle stability of alloys electrodes(S₁₀₀=87%).

Abstract: The electrode structure, especially for the channel depth, plays an important role on the performance of the proton exchange membrane (PEM) fuel cell. In this paper, the performance and electrochemical impedance of the PEM fuel cell are measured experimentally. The simulation results of mass transfer and equivalent circuit for the electrochemical impedance are used to explain the effect of the channel depth on the performance of the PEM fuel cell. These results show that when the cell temperature is lower than the gas humidification temperatures, the performance of PEM fuel cell with the channel depth of 2mm is better than that of 1mm; there is more liquid water saturation in cathode for the channel depth of 1mm than that for the channel depth of 2mm. The charge transfer resistance of the PEM fuel cell with the channel depth of 2mm is less than that with the channel depth of 1mm. These results are very helpful to optimizing structure of the PEM fuel cell.

Abstract: A new hydrocarbon-type polymer electrolyte membrane has been developed as a candidate of commercially available product for DMFC application. The membrane shows lower methanol crossover and swelling in the methanol aqueous solution than perfluorosulfonic acid membrane does. As a result, MEA made from the membrane showed higher power density than that of perfluorosulfonic acid membrane at higher concentration of feed methanol solution and higher current density without tremendous flooding. Promising result of the practical durability with continuous fuel cell operation for 8000 hours was also confirmed with this membrane.

Abstract: Electrically conductive fabrics were prepared with interlacing polyester yarns and wrapped yarn of polyester/NiCr filament. The wrapped yarns are lined in different distance along filling direction, and the effect of distance on electrically conductivity of fabrics with plain weave is analyzed. In addition, wearing properties including fabric thickness and air permeability of such fabrics are also tested. The results show that surface charge density decrease with number increase of wrapped yarns in filling direction. When wrapped yarns are arranged at 3 yarns/ 6 cm for twill weave, the fabric density and air permeability increase with fabric density.

Abstract: PET/PTT conjugate yarn has a three-dimension spiral and permanent crimp, which endow the yarn and loomage with excellent performances of crimp extension and crimp recovery. The residual deformation and internal stress of the self-crimp yarn can be eliminated after the moist heat treatment, in order to develop the favorable crimp extension and crimp recovery of the self-crimp yarn, and to give the loomage soft handle and good dimension stability. Crimp shrinkage, crimp module, etc, of the different types of PET/PTT yarn, were tested, and the axial morphology of the yarn was observed, to investigate the effect of linear density, moist heat temperature on PET/PTT yarn.

Abstract: The effect of blending ratio and yarn twist multiplier on Polysulfone /Meta-aramid blended yarn properties is studied. Two-factor analysis of variance shows that yarn twist multiplier and blending ration have a significant effect on yarn breaking strength while yarn breaking elongation is affected by yarn twist multiplier considerably. Yarn evenness varies with blending ration delicately. Blending ratio and yarn twist multiplier have little effect on yarn hairiness. Yarn evenness nearly has no change with yarn twist multiplier and yarn breaking elongation remains consistent under different blending ratios. Yarn breaking strength gets higher with Meta-aramid content increasing. When the yarn twist multiplier is small, it’s easy to increase yarn strength by blending high-strength fibers. Yarn breaking elongation gets higher when yarn twist multiplier is larger. Blended yarn evenness gets better with finer Meta-aramid content increasing.

Abstract: In order to have a better understanding of mechanical properties of the Nano-TiO₂ antibacterial cotton fabric, FAST system was used to measure the compression, bending, shearing, extension and other low stress mechanical properties of cotton fabrics with and without treated by Nano-TiO₂ antibacterial. The structural parameter and dimensional stability are also tested. Results indicated that weight, weft density, surface thickness, bending, formability, shearing and relaxation shrinkage of weft direction are all increased slightly, while shearing at warp 45°, relaxation shrinkage of warp direction and hygral expansion decreased. As a whole, most of the mechanical properties are still within the normal range and some is even better.