Advanced Materials Research Vols. 760-762

Abstract: The room-temperature mechanical properties of the extruded Mg-5Li-3Al-2Zn-2Cu alloy (LAZ532-2Cu) were researched previously. In this paper, the creep behavior of the extruded LAZ532-2Cu alloy was studied at the temperature range from 398K to 448K, with the stress 60MPa, 80MPa and 100MPa. The microstructure of the alloy consists of the matrix α-Mg solid solution and the intermetallic compounds on the grain boundary or in the grain. The microstructural analysis of the alloy reveals the correlation between microstructure and creep properties. The stress exponent n 3.72, 4.8, 6.1, the activation energy Qc 94.8kJ/mol, 123.9kJ/mol, 128 kJ/mol were calculated at the test condition. The creep test samples were combined with detailed transmission electron microscopy and X-ray diffractometry in order to characterize the precipitated AlLi phase, which contributes to the creep resistance by obstructing the dislocation movement in dislocation creep.

Abstract: Na_0.48K_0.47Li_0.05)NbO₃(NKLN)Lead-free piezoelectric ceramics doped with CuO were prepared by traditional solid-state reaction method. Influence of calcined temperature on the material phase of NKLN lead-free piezoelectric ceramics doped with CuO by X-ray diffraction (XRD) and the influence of calcined temperature and sintered temperature on the properties of NKLN lead-free piezoelectric ceramics doped with CuO by others analysis method. The results show that the best calcined temperature is got, when calcined temperature is up to 850 °C, the mixed phase disappeares, a single phase perovskites structure is formed. With the increase of calcined temperature, piezoelectric strain constant (d₃₃) planar electromechanical coupling factor (K_p) of NKLN lead-free piezoelectric ceramics increase first and then decrease, while only dielectric loss (tanδ) decreases first and then increases.The best calcined temperature is 850 °C, the best sintered temperature is 1080 °C, the NKLN lead-free piezoelectric ceramics doped with CuO with good comprehensive properties are obtained, whose d₃₃ , K_p , tanδ are 85 pC/N, 0.3, 0.038, respectively.

Abstract: The dielectric properties of (1-x) Ba_0.65Sr_0.35TiO₃-xCaTiO₃(x=0, 0.03, 0.06, 0.10, 0.15) ceramics were investigated. XRD analysis shows that CaTiO₃ doping can be fully incorporated into the perovskite lattice of BST except increasing peak intensity. The experimental result shows that doping a certain amount of CaTiO₃ could form fine crystal grain structure, enhance the density, and enhance Ac withstand voltage strength, increase dielectric constant and decrease the dielectric loss. While doping excessive CaTiO₃ could make the geometrical distortion, increase the porosity and grain size, develop the internal stresses and finally lead to the dielectric constant decrease. The BSTC ceramics sintered at 1350 °C for 2 h with 6 mol.% CaTiO₃ doping has the best properties, ε_r of 3862, tanδ of 0.046, E_b of 5 kV/mm (AC), the value of C/C ranges is-26.7%~-66.2% in-50 °C ~ 100 °C temperature range.

Abstract: Bi₂(Mg_l/3Nb_2/3-xTi_x)₂O₇(BMNT)(x=0.1, 0.15, 0.2, 0.25) ceramics was prepared by conventional solid phase method, The influence of titanium ion doped amount on the dielectric property and microstructure of BMNT ceramics were systematically studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and other testing and analysis how to methods. Results show that there is single monoclinic pyrochlore phase and there is not the second phase in all BMNT ceramics doped with titanium ion. The grain size of BMNT ceramics increases first and then decreases, the dielectric constant (ε_r) increases first and then decreases, the dielectric loss (tanδ) increases first and then decreases, the ceramic density decreases all the time while titanium ion doped amount increases. The ceramic density increases first and then decreases when sintered temperature increases. The density of BMNT ceramics doped with titanium ion is biggest when sintered temperature is 980 °C. When sintered temperature is 980 °C and titanium ion doped amount is 0.15mol, the dielectric properties of BMNT ceramics is good,which ε_r is 135(1MHz), tanδ is 0.002(1MHz) and volume density is 7.46g/cm³.

Abstract: In the present work, we investigated the effect of sputtering power on the structural and optical properties of ZnO films by radio frequency (rf) magnetron sputtering. Atom force microscopy (AFM), X-ray diffraction (XRD) and Prism coupling method were adopted to investigate the structure and optical properties of ZnO thin films deposited by sputtering powers in the range from 100~150W. XRD and AFM results shown that ZnO films with high c-axis preferred orientation crystalline structures have been successfully deposited under higher sputtering power condition. Moreover, it was also found that the indexes refractive of the films obtained by higher sputtering power are less than that of the bulk ZnO materials, which is closer to Crystal Refractive index.

Abstract: A study on low pressure water jet assisted laser processing is presented. This new method is researched by drilling on Al₂O₃ ceramics material. A comprehensive research on the influence of laser processing parameters on surface quality with this method is conducted. The microcosmic appearances of the machining surfaces obtained from normal laser processing and composite processing were comparatively analyzed. At the same time, through measuring the holes in the 3-D morphology, the influences of water jet velocity and laser processing parameters on the surface quality are presented. The results show that, the surface quality is significantly improved with this new method which combines low pressure jet into laser processing. The molten slag can be significantly reduced and the stability of processing quality can be improved much.

Abstract: This article mainly introduces the manufacture and application principle of photosensitive color-changing fiber and thermosensitive color-changing fiber in clothing color-changing materials so as to let people better understand them.

Abstract: A simple synthetic route to create Nickel nanoparticles/MWCNT composites (NiNPs/MWNTs) is reported. The process is concise, no additional surfactant or other reducing gas was employed. TEM, SEM, XRD and EDX were used to examine the morphology of the nickel particles. In this experiment, the hydrothermal method using ethylene glycol as a solvent has been well dispersed, uniform size and smaller particle size of the nickel nanoparticles with average size about 50 nm. By cyclic voltammetry test results show that with good electrical properties, Ni / MCNTs.

Abstract: This paper presents a synthetic method of graphene load nickel nanoparticles composites. Hydrothermal process is simple and convenient way, neither surfactant is needed nor by products will exist serve hydrazine hydrate as reductant. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses were used to characterization the morphology of the graphene load nickel nanoparticles composites, and cyclic voltammetry (CV) was used to characterization the electrical properties of the composites. The results of XRD and FTIR show that the complexes were successfully synthesized by this method. Moreover, the good dispersibility and relatively uniform particle size of the complexes can be obviously observed from the SEM image. And the cyclic voltammetry curves exhibit good electrical properties of graphene load nickel nanoparticles composites. All the conclusions are based on the experimental results.

Abstract: The electrospinning combined with the sintering process were used to prepare carbon-coated lithium iron phosphates (LiFePO₄/C) cathode materials for lithium ion batteries (LIB). In sintering process, different procedures were used to synthesize the LiFePO₄/C composite materials. The effect of the sintering time and heating rate on the structure, surface morphology and carbon content of LiFePO₄/C composite materials were investigated by wide angel X-ray diffraction (WXRD), scanning electron microscope (SEM), and elemental analysis (EA) techniques. It has better structure when the sintering process is as follows: heating rate is 2 oC min^-1 and pre-oxidized time is 3h at 280 oC and carbonized time is 8h at 700 oC.