Advanced Materials Research Vols. 239-242

Abstract: Bi_3.15Nd_0.85Ti₃O12 (BNT) thin films with different thicknesses (200, 270, 360, 450 and 540 nm) were prepared on Pt/Ti/SiO₂/Si substrates by sol–gel method. The effect of film thickness on the microstructure and ferroelectric properties of BNT thin films was investigated. All BNT thin films were consisted of a single phase of bismuth-layered perovskite structure. With increasing film thickness, grains gradually became larger, the remanent polarization (2P_r) firstly increased and then decreased, and the leakage current density showed opposite trend. The 360 nm-thick BNT film exhibited better electrical properties with 2P_r 26 µC/cm², coercive field (2E_c) 220 kV/cm, dielectric constant 345 (at 1 MHz) and low leakage current density.

Abstract: The microstructure of two kinds of self-made PAN-based high-modulus carbon fibers (HMCF-1, HMCF-2) was studied by scanning electron microscopy (SEM), Raman spectroscopy, X-ray diffraction (XRD) and high resolution transmission electron microscopy (HRTEM), and was compared with that of T800 and M55J. The correlation of XRD and HRTEM in terms of graphite crystallite sizes and interlayer spacing of graphite layer was also investigated. The results show that the diameters of T800, HMCF-1 and HMCF-2 are almost the same (~5.20μm) and all of them are lager than that of M55J (~4.86μm). The crystal sizes and the degree of graphitization are in the order of HMCF-2>HMCF-1>M55J>T800, while the regularity of the lattice fringes of HMCF-2 is better than those of others.

Abstract: An expression of monolayer capacity for hydrogen adsorption was derived on the basis of Ono-Kondo lattice theory. And then, the interaction energies between hydrogen molecules and pore surface atoms in the zeolite were calculated by using Lennard-Jones (12-6) potential model for spherical pores. The results show that the monolayer capacity is dependent on adsorbate–adsorbent and adsorbate–adsorbate interaction energies, and that the interaction energies of hydrogen-zeolite agree with the previously reported isosteric heat of hydrogen on zeolites.

Abstract: The Mg-6%Zn-5%Hydroxyapatite (HA) biomaterial had been prepared through powder metallurgy method in this investigation. The mechanical properties and biodegradable behaviors of the Mg-Zn-HA composite in simulated body fluid were studied. The Mg-Zn-HA specimens obtained appropriate density, adjustable elastic modulus and compatible strength to natural bones. Immersion corrosion experiments revealed that 5wt% addition of HA in Mg-6%Zn alloy exhibited acceptable corrosion rates in simulated body fluid. The Mg matrix, Mg₇Zn₃ phase and HA are identified in the experimental composite. The Mg(OH)₂ and Hydroxyapatite were found on the corrosion products in the simulated body fluid.

Abstract: The action mechanism of ultrasonic was investigated when the ultrasonic wave as a new kind of energy importation way was introduced in the technology of electroless plating at low temperature. Compared with common electroless plating coatings, influence factors of improving the properties of the Ni-Cu-P Alloy coating under ultrasonic were analyzed through hardness, dense nitric acid spot testing metallographic structure observation and EDS. Experimental results show that, under the effect of ultrasonic, the obtained Ni-Cu-P coating has more fine crystal grain, even and dense surface morphology. Its corrosion resistance and hardness have been improved obviously.

Abstract: Using solvents extraction separation system of self-designed make superior coal tar pitches for carbon materials. In proper order choose petroleum ether, methanol and carbon disulfide to cut coal tar into several fractions under different condition. The first solvent can take light components out from coal tar. Then drag out those chemical that contain heteroatom such as nitrogen, sulfide applying the second solvent. The last is to dig out higher molecular weight polycyclic aromatic hydrocarbon from coal tar deeply. Heavy fractions are vacuumed to drive out any solvents. The superior chirpy coal tar pitches for carbon materials acquired.

Abstract: SUS316L austenitic stainless steel was subjected to severe plastic deformation (SPD) by the method of high pressure torsion (HPT). From a fully austenitic matrix (γ), HPT resulted in phase transformation from g®a¢. The largest volume fraction of 70% a¢ was obtained at 0.2 revolutions per minute (rpm) while was limited to 3% at 5rpm. Pre-straining of g by HPT at 5rpm decreases the volume fraction of a¢ obtained by HPT at 0.2rpm. By HPT at 5rpm, a¢®g reverse transformation was observed for a¢ produced by HPT at 0.2rpm.

Abstract: First-principle calculations on the electronic structures and optical properties of CuIn_1-xGa_xSe₂(x=0, 0.25, 0.5, 0.75 and 1) reveal that CuIn_1-xGa_xSe₂ are small band gap materials and the ground state is stabiles from x=0 to 1 while the band-gap of the quaternary compound widen, all of that are in good agreement with the experimental results. We find that the obviously double peak structure of the imaginary of dielectric function centered about from 0.9 to 5.0 while a distinct peak appears at about 2.2eV and a smooth increasing with another peak appearing at about 5.5eV for the different content of Ga appearing in the absorption spectrum, all of which indicate the different band gap for the transition.

Abstract: In this paper, the influence of ageing and solution treatment on the low cycle fatigue behavior of a rolled AZ80 magnesium alloy sheet was investigated at constant total strain amplitudes between 0.003 and 0.01. It was observed that fatigue life of the alloy sheet at as-rolled, ageing and solution treatment conditions can be described well by Coffin-Manson and Basquin’s equations. The fatigue parameters follow the two equations were evaluated. With increasing total strain amplitude, the fatigue life of the three conditions decreased. At the lowest total strain amplitude of 0.003, the fatigue life of the as-rolled alloy sheet was the biggest. However, at the highest total strain amplitude of 0.01, the fatigue life of solution treated alloy sheet was the biggest, and that of the ageing treated alloy sheet was the shortest.

Abstract: Based on TEOS system and sol-gel process, together with catalysts, the microstructure of SiO₂ particles in the sol is exactly controlled. The films are characterized by ellipsometer and SEM respectively. The experimental results show that adjusting catalytic agent can effectively effect the structure of SiO₂ thin film.