Key Engineering Materials Vols. 531-532

Abstract: Polysulfone (PS) hollow fiber microporous membrane was used as substrate, the micropores of which were filled with surface-modified zeolites suspension on the outer surface by vacuum method, and then zeolite-filled poly(piperazine-amide)/PS hollow fiber composite membrane was synthesized on the substrate by interfacial polymerization reaction with piperazine (PIP) aqueous solution and trimesoyl chloride (TMC) n-hexane solution. The substrate membrane and synthetic composite membrane were characterized by scanning electron microscopy (SEM). A thin poly(piperazine-amide) active skin layer was synthesized on the substrate and the surface-modified zeolite particles were successfully embedded in the surface micropores of the substrate. The separation factors of the sample to K⁺ are 4.25, 60.46 and 93.61 in the mixed K⁺-Na⁺, K⁺-Ca²⁺ and K⁺-Mg²⁺ solutions respectively, which indicates that the sample has preference selectivity to K⁺ and can be used as a potential ion-exchange membrane for potassium continuous extraction from seawater.

Abstract: Ceria-based solid electrolyte was prepared by low-temperature combustion method, and the synthesis technology was discussed. It can be found that the advantages of choosing citric acid as reducing agent were higher yield and easier reaction control. The crystalline growth of samples was tended to complete when the pre-sintering temperature was 700°C. There was not stratification phenomenon when the forming pressure was 400 MPa. Nano-scale powders were obtained by this way, which caused decreasing of sintering temperature. The effects of Ce0.8Gd0.2O2-δ (CGO) doped manganese oxide as sintering additive on density and conductivity were studied. The relative density of CGO doped 2.0 mol% MnO1.333 (2Mn-CGO) increased within a certain temperature range because of the occurrence of viscous flow sintering. The conductivity measured at 700 °Cof 2Mn-CGO sintered at 1100 °C was 4.52×10-2 S/cm, which is higher than that of CGO.

Abstract: We study modes excitation with input field of different positions in five-mode photonic crystal waveguides of triangular lattice. The five-mode photonic crystal waveguides is formed by removing five rows rods in 2D photonic crystals of a triangular lattice of dielectric rods in air. The 0th mode, the 1st mode and the 2nd modes are selectively excited. The input field with different positions can excite different modes due to the field intensity distribution of modes. When the input field locates at the position of the zero field intensity of the waveguide mode, the mode can not be excited. The superposition of different modes can leads to different field intensity distribution. The finite-difference time-domain method is used to obtain the excited field distributions.

Abstract: Nano copper /paraffin thermo sensitive composite was prepared by high energy milling and pressed into a glass cylindrical tube by using thermoforming process. Thermo sensitivity of the thermo sensitive composite was tested by thermo sensitivity tester which is developed by us. The composite particles with good cladding effects, prepared by high energy milling, arrange close together. Copper particles have no damage on the structures of paraffin. The thermal conductivity of thermo sensitive composite is enhanced with the increase of mass ratio of copper powder.

Abstract: It is hardly possible to obtain rare earth doped CaWO₄ thin films directly through electrochemical techniques. A two-step method has been proposed to synthesize Tb³⁺-doped CaWO₄ thin films. X-ray diffraction, energy dispersive X-ray analysis, spectrophotometer were used to characterize their phase, composition and luminescent properties. Results reveal that Tb³⁺-doped CaWO₄ films have a tetragonal phase. The ratio of n(Tb)/[n(Ca)+n(Tb)+n(Na)] decreases with the increase of pH value of TbCl₃ solutions. When the pH value (adjusted by NaOH) is higher than 5, Na element has been detected in CaWO₄:Tb³⁺ thin films. Based on the analysis on the composition and luminescence, it can be concluded that the pH value of TbCl₃ solutions must be no higher than 9.1, otherwise, no Tb³⁺-doped CaWO₄ thin films can be obtained. Under the excitation of 237 nm, sharp emission peaks at 543 and 489 nm have been observed for Tb³⁺-doped CaWO₄:Tb³⁺ thin films.

Abstract: The mixed powders of 70%Fe and 30%Al were precoated, and Fe-Al intermetallics coatings were produced on an aluminum ZL114A alloy by means of laser cladding. The microstructure and hardness of the coatings are analyzed by using optical microscopy (OM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and microhardness testing machines. The results show that a fine surface quality can be obtained under a suitable process parameter of laser. The laser cladding layers are mainly consisted of phases of FeAl3, Fe3Al, FeAl with lump-like, granular, equiaxial and needle-like. The highest microhardness of the cladding layer achieved HV614 and raised 5~6 times in comparison to substrate.

Abstract: We added different amount of Fe (NO3)3 to the solution made of aluminum nitrate, copper nitrate and isopropanol to form gel. CuAl1-xFexO2 (x = 0, 0.01, 0.03, 0.05, 0.07, 0.09) powders and films were prepared in our experiments. The films were prepared on the quartz substrates. The powders and films were annealing at 1050 °C for 5 hours in the air. The powders were detected by X-ray diffraction to represent the structure of CuAl1-xFexO2. The square resistance of the films was determined by RTS-8 four-probe. The lowest square resistance is of CuAl0.95Fe0.05O2 film 3.3 KΩ/□ .Ultraviolet spectrophotometer (UV-3600, 230VCE) was used to measure the transmittance of the films. Fe-doping has a positive impact on the conductivity but negative impact on the transmittance.

Abstract: Sm³⁺ doped YAG glass ceramics containing single phase of YAG micro-crystals have been obtained by heat-treating the aluminosilicate precursor glasses. The YAG crystals grow with several preferred orientations and a dominant one (444) in the matrix, and present microcrystal sizes in the range of 3~15µm. The pilotaxitic texture existed in internal network of the YAG glass ceramics can increase yield strength and tensile strength of the sample effectively. Typical visible transition emissions of Sm³⁺ have been observed in the YAG glass ceramics under the excitation of short-wavelength visible light, and the spectral intensity ratio between the electric dipole ⁴G_5/2→⁶H_9/2 and the magnetic dipole ⁴G_5/2→⁶H_5/2 transitions is lower than the values reported in the optical glasses specifying the enhanced symmetric nature in the Sm³⁺ doped YAG glass ceramics. The obvious Stark splitting exhibited in emission spectrum manifests that rare-earth ions have been incorporated into YAG lattices.

Abstract: Individual corrosion and galvanic corrosion behaviors of depleted uranium (DU) and 40Cr steel were investigated by electrochemical analyzing technologies in 3.5w.t%NaCl solution, including open circuit potential(OCP) test, linear polarization(LP) test, potentiodynamic polarizaition(PD) test, galvanic corrosion potential and corrosion current density test. The results reveal that the OCP of DU and 40Cr steel are around -790mV and -660mV, respectively. 40Cr has a higher linear polarization resistance than DU in galvanic corrosion. The dynamic processes of galvanic corrosion goes through an conversion in the whole test period. DU acts as anode with an accelerated corrosion rate, while the 40Cr steel behaves as cathode during the process of galvanic corrosion for DU/40Cr couple. The galvanic potential and current density of the DU/40Cr couple are -780mV and 17.5μA/cm-2, respectively.

Abstract: A new synthetic technology of Strontium carbonate with high gravity is introduced in this paper. We got ultrafine SrCO3 powders with Sr(NO3)2 and NaCO3 or CO2 as raw material by high gravity method. We studied flows, the rotating speed, additives and CO2 as the reactants on the morphology of strontium carbonate. The results show that the presence of additive-free, we got rod-like structure of strontium carbonate. Added EDTA, we got a good dispersion of spherical particles of narrow particle size distribution. The presence of EDTA, the average particle size of spherical particles decreases with the speed increases. CO2 alternative Na2CO3 as the reactants, the presence of additive-free, we got the bundle structure of strontium carbonate. The presence of EDTA, we got spherical particles, but the particle dispersion is not well, gathered together.