Advanced Materials Research Vols. 79-82

Abstract: Electrical conductivity, tensile strength and micro-hardness of Cu-3.5wt.%Ti-0.1wt.%Zr-RE alloy were investigated after optimizing technics of plastic deformation and the heat treatment. The results show that good combination of the physical and mechanical properties, such as tensile strength 1160 MPa, micro-hardness 335 Hv and electrical conductivity 15 IACS% can be obtained on peak aging at 420°C for 7 h. Maximum strength was associated with the precipitation of metastable, ordered and coherent β/ (Cu4Ti) phase on peak aging. Then the strength decreased due to the precipitation of β (Cu3Ti) phase in alloys overaged.

Abstract: YSZ electrolyte-supported hollow-fiber SOFCs were successfully fabricated and their electrical and mechanical properties were investigated. The as-prepared hollow fiber SOFCs show a high mechanical strength of 149.0 MPa and 177.9 MPa before and after reduction by hydrogen gas, respectively. The open circuit voltage (OCV) values are greater than 1.0 V and the maximum power densities reach 146 mW cm-2 at 800°C, using wet H2 (～3% H2O) and static air as fuel and oxidant gas, respectively. As a result of high packing densities, this kind of YSZ electrolyte-supported hollow-fiber SOFCs has a high potential for practical applications.

Abstract: In this paper, the hydrogen permeation performance of Ni-La1.95Ca0.05Ce2O7-δ (Ni-LDC) was measured in an H2S-containing atmosphere at 1073K. In 75, 150 and 300 ppm H2S, the hydrogen permeation flux decreased by about 5%, 15%, 30% respectively. XRD analysis revealed that sample showed a little formation of Ni3S2, La2O3, LDC, Ni, Ce2O2S. Based on the analysis of the microstructure and phase composition, and results of thermodynamic calculation, we suggested that the reaction between H2S and CeO2 is main cause of hydrogen permeation performance of the Ni-La1.95Ca0.05Ce2O7-δ cermet lossing.

Abstract: The phase transformation characteristics, the dynamic elastic modulus and the static tensile elastic modulus of Ti50Ni47.5Fe2.5 alloy were investigated. It is found that, the two mutations in the dynamic elastic modulus is caused by reverse martensite phase transformation and austenite phase transformation respectively; Static tensile test can not reflect the intrinsic elastic modulus when the test temperature is close to martensite transformation temperature(Ms). The static elastic modulus and the dynamic elastic modulus have the same trend when the test temperature is enough higher than Ms.

Abstract: Three new zinc porphyrins ( [5,15-bisferrocenyl-porphyrinato]-zinc(II)(4), [5,15-bisferrocenyl-10,20-bis(4-nitro-phenyl)-porphyrinato]-zinc(II)(5), and [5,10,15,20- tetraferrocenyl-porphyrinato]-zinc(II) (6)) with ferrocenyl units at the meso-positions of porphyrin ring have been prepared and characterized. Towards further understanding the fluorescence quenching and recovery of ferrocene-porphyrins, the fluorescence spectra of these compounds was detailedly studied.

Abstract: Self –organized InAs quantum wires (QWRs) were fabricated on the step edges of GaAs (331)A surface by molecular beam epitaxy (MBE). The atomic force microscopy (AFM) results show that the lateral size of InAs QWRs is 90 nm while the size along the step lines increasing with the thicknesses of InAs layers, amounting to 1100nm. The height of InAs QWRs varies from 7.9nm to 13nm. Photoluminescence (PL) measurements on the two samples were explored and an obvious PL peak around 967 nm was observed at 25 K. The PL intensity decreases as the temperature increases, and it will vanish above 60 K. However, the QWR sample with thicker InAs layer emits a long emission of 1100 nm -1400 nm as the temperature rises above 50 K, and a longer emission of 1400-1600nm as the temperature approaches to 100 K. We considered that the complex photoluminescence spectra were originated from the multiple energy steps. The carrier migration among the different QWRs structures intensified with temperature, and the chance rate from the higher energy levels to the lower ones which generated a stronger emission of long wavelength. The carrier dynamics of QWR samples were measured by using time resolved PL (TRPL) spectra from 25 K to 100 K. The PL decay time in the QWR structure at longer emission was found to be independent of the temperature as T<100 K, showing a typical dynamical behavior of the localized excitons.

Abstract: For the first time, nano-scale rods of NaLaxYb9-x(SiO4)6O2 (x=1,3,5,7,9) crystals (NLS) activated with Er3+ have been synthesized through a mild hydrothermal conditions with subsequent calcination. The as-obtained products were characterized by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The results indicate that the compound has an apatite structure and crystallizes in the hexagonal system, space group P63/m. The excitation spectrum and emission spectrum were also emplyed to investigate the optical properties of the nano-rods. The Er3+ doped NLS exhibit green/red up-conversion luminescence under excitation with a diode laser at 980 nm.

Abstract: Phosphate-bonded investment（PBI）ceramic mold materials have outstanding properties, such as rapid setting rate , moderate green strength and high temperature strength, and could be widely utilized in dental restoration and micro-casting of artistic products. However, fast hydration and gel rate of the phosphate-bonded ceramic slurry has been an obstacle to the wide applications of ceramic mold material for medium and large-size precision castings. This paper presents a new phosphate-bonded ceramic mold material by modifying the composition of refractory aggregates and additive agents, which is promising to be used for rapid ceramic mold casting for medium-size super alloy components. The results indicate that the properties of ceramic mold slurry including initial setting time and fluidity are suitable for complete embedding medium-scale patterns and get accurate duplicate of external configurations when the amount of boric acid is 1.11wt% and sodium tri-poly phosphate (STP) is 0.92wt%. The strength of ceramic mold material can resist impact force when pouring molten metal and easy take casting out from ceramic mold.

Abstract: Attapulgite clay(ATP) from Xuyi county of China was purified by a wet method then treated with NaOH and 1.0 mol/L, 2.0 mol/L and 3.0 mol/L solutions of HCl. Transmission electron microscope(TEM) and X-ray diffraction (XRD) were used to characterize treated ATP. Results showed that wet purification could remove most of impurities. Treatment by alkaline and HCl of 1.0 mol/L and 2.0 mol/L could increase purity while treatment of 3.0 mol/L hydrochloric acid could dissolve some element of ATP so much as form SiO2 and destroy fiber structure to clips. Adsorption experiments of Fe3+ and Ni2+ from aqueous solutions were done using original ATP, purified ATP and treated ATP as absorbents. Results showed that Attapulgite could adsorb metal cations in significant amounts. Sodium hydroxide activation had little influence on adsorption capacity. Influences of acid treatments to ATP on adsorption capacity varied on different concentration solutions.

Abstract: The two-phase perovskite manganese composites have potential application in the field of spintronics, as the observed enhanced low-field magnetoresistance in this kind of composite. To prepare the real manganite-based two-phase composition, the concept of bonded perovskite manganese was put forward recently. In this article we review main research results in these bonded perovskite manganite oxide composites and give some expectation.