Advanced Materials Research Vols. 239-242

Abstract: Shape memory polyurethane (SMPU)/Vapor grown carbon nanofibers (VGCNF) composites with different surface functionalized method were prepared via sol-gel process. The structure and properties of the composites were investigated by scanning electron microscopy (SEM), universal testing machine, and dynamic mechanical analysis (DMA). The results show that the dispersion of VGCNF with surface modification in matrix is better than that of pristine. The mechanical properties of the composites with VGCNF modified by concentrated nitric acid deteriorated substantially. However, both the tensile strength and elongation at break of the composites combined surface modification of silane coupling agent and sol-gel method increased obviously. The substantially improved mechanical properties are mainly attributed to the cross-link between coupling agent and the network structure of SiO₂ produced during the sol-gel process. The DMA analysis suggests that the surface treatment of the VGCNF exhibit obviously effect on the dynamic mechanical properties of the composites.

Abstract: In order to improve and simplify the process of electroless Ni-P plating on aluminum substrate, a activated solution and process were optimized by orthogonal test, the plating morphology were analysed using Quanta 200 type scanning electron microscope. The bond between the plating and aluminum substrate were evaluated using method of water quenching and alternating bending test. The results show that good coating can be obtained on aluminum substrate under the normal condition of the acid electroless Ni-P plating solution with sulfuric acid of 120g/L and nitric acid of 10-15g/L as activated solution and activated time of 20 min. And the good bond between the plating and aluminum substrate was obtained.

Abstract: As high-temperature metallic materials, Co-base ODS alloys were produced by means of mechanical alloying, spark plasma sintering and hot rolling. Co-3wt%Al-1.2wt%Hf-ODS alloy was found to be an attractive composite like material, which is formed by spinodal like decomposition. The metastable phases were traced by hard phase containing dense oxide particles and soft one containing less oxide particles. Their tensile stress at 1,000 °C was improved by Hf addition that forms Y₂Hf₂O₇ type oxide particles and shortens their space distance.

Abstract: A kind of novel hypercrosslinked resin containing hydroxymethyl group was firstly synthesised via chloromethylation of benzyl alcohol monomer and succedent Friedel- Crafts alkylation polymerization. The structure and micromorphology of the resin was characterized with BET, IR and elemental analysis. The results indicated that the novel polar adsorption resin possess high specific surface area (525.00m²/g) and abundant micropore structure (average pore diameter: 1.123nm), and could be anticipated having a potential application in the fields of solid phase synthesis, separation and adsorption.

Abstract: In this paper, the probabilistic compliance methodology for damage tolerance design of thicker composite structures were investigated, and the research results show that for the composite laminates withstanding impact energy below 90J, if it cannot produce barely visible impact damage (BVID), then using the probabilistic methodology can meet certification requirements of damage tolerance.

Abstract: As an advanced manufacturing technology, tailor welded blanks (TWB) not only meet different requirements of properties in different parts, but also can satisfy the requirements of weight reduction and energy conservation. 6061 aluminum alloy with the thickness of 1mm was jointed by laser beam welding technology and the microstructure of tailor-welded joints was analyzed compare to base metal. The forming and bulging property characteristics of TWB were evaluated through tensile and cupping tests. Experimental results indicated that: the weld joints contained fine equiaxed grains in the center of the weld and columnar grains and dendrites near the fusion boundary were observed to be oriented towards the center of the weld. The dendrites became smaller and thinner during the transition process from the weld fusion boundary to the center. The fracture path of the TWB tensile specimens occurred in the heat-affected zone (HAZ) with the tensile and yield strength increased while the strain hardening coefficient and elongation reduced compared to base metal. The erichsen index of TWB in the cupping test was lower than base material, which demonstrated that the bulging property of the TWB was worse than base metal.

Abstract: Using chemical vapor deposition (CVD) method and purified air as carrier and diluent gas, ZnO thin films was prepared with zinc acetate on glass substrate. Crystalline and optical properties of ZnO thin films were respectively tested by X-ray diffractometer (XRD) and UV-light spectrophotometer. The results showed that crystal face (002) of thin films was preferred orientation. In the visible region, the transmittance was over 85%. When ZnO thin films was prepared at 500 °C, the crystallization of ZnO thin films was the best, and when the temperature was 450 °C, the grain size of thin films was the least, and internal stress was the least. With the substrate temperature increased, ZnO thin films both showed blue shift of the absorption edge and decrease of band gap.

Abstract: α-Fe₂O₃ mesocrystals and nanorings have been prepared by hydrothermal method, using phosphate and sulfate ions as additives. Hydrothermal treated at 180 °C for 24 h in presence of C₃H₈NO₆P and Na₂SO₄ leads to the formation of capsule-shaped α-Fe₂O₃ mesocrystals, when the reaction time prolonged to 96 h α-Fe₂O₃ nanorings formed. It can tune the size and morphology of the final products by varying the ratios of phosphate and sulfate ions to ferric ions. XRD, SEM, TEM, HRTEM, UV-Vis, FT-IR were used to characterize the products. A formation process involving the selective adsorption and the cooperative coordination effect have been deduced.

Abstract: In this study, thin films of CaBi₄Ti₄O₁₅ with preferential crystal orientation were prepared by the chemical solution deposition (CSD) technique on a SiO₂/Si substrate. The films consisted of a crystalline phase of bismuth-layer-structured dielectric. The as-deposited CaBi₄Ti₄O₁₅ thin films were crystallized in a conventional furnace annealing (RTA) under the temperature of 700 to 800°C for 1min. Structural and morphological characterization of the CBT thin films were investigated by X-ray diffraction (XRD) and field-emission scanning electron microscope (FE-SEM). The impedance analyzer HP4294A and HP4156C semiconductor parameters analyzer were used to measurement capacitance voltage (C-V) characteristics and leakage current density of electric field (J-E) characteristics by metal-ferroelectric-insulator- semiconductor (MFIS) structure. By the experimental result the CBT thin film in electrical field 20V, annealing temperature in 750°C the CBT thin film leaks the electric current is 1.88x10^-7 A/cm² and the memory window is 1.2V. In addition, we found the strongest (119) peak of as-deposited thin films as the annealed temperature of 750°C

Abstract: In this study, we investigated that of Al/ Ba(Zr_0.1Ti_0.9)O₃ (BZT)/Pt/Ti/SiO₂/Silicon metal-ferroelectric-metal-insulator-semiconductor (MFM) ferroelectric structures and found the memory effect and capacitance of annealed BZT films during the different annealing temperature. Additionally, the capacitance and leakage current density were about 4.3 nF and 1´10^-6A/cm², respectively. From C-V curves, the ferroelectric properties and charges accumulation of annealed BZT films were also found during the annealing temperature of 700°C.