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December 15,2015
Volume 8,Issue 23
Pages -
Subject Area:Composite Materials

Title: System identification method for cashmere and wool

Authors: LIU Mingwu, ZHANG Juan, AO Jianfang, GONG Yan
PP: 2514-2521
Abstract: By using microscopy, Raman spectroscopy method as well as DNA analysis to identify comprehensive cashmere and wool. Through scanning electron microscopy (SEM), transmission electron microscopy (TEM), external and internal organizational structure of cashmere and wool were observed. Rapid determination content of disulfide bonds of cystine in cashmere and wool were carried out by Raman spectroscopy. Gross qualitative and quantitative analysis of cashmere and wool were given by DNA analysis. In combination, we create a system of identification method for cashmere and wool testing.
Keywords: wool spining; cashmere; wool; identification

Title: Preparation and research of mesoporous perovskite-type La-Co-O

Authors: LIAO Hui, HUANG Xuehui
PP: 2508-2513
Abstract: Silicon-based mesoporous materials have excellent thermal stability, high specific surface area and large pore volume. It has obvious advantages in the synthesis of mesoporous materials in the use of ‘inverse structure’. The mesoporous molecular sieve SBA-15 was synthesized by hydrothermal method. Then using SBA-15 as hard template, we prepared mesoporous perovskite-type LaCoO3 by the hard-template wet impregnation sol-gel method. The article also researched the influence of template agent content on the crystal phase and the specific surface area of the LaCoO3 perovskite. Finally, the catalytic conversion efficiency for CO gas was studied. The experimental results show that mesoporous molecular sieve SBA-15 has hexagonal ordered mesoporous structure, high specific surface area (807 m2/g) and a narrow pore size distribution (the most probable pore size is 5.6 nm). The content of template agent plays a decisive role in specific surface area of LaCoO3 samples. When the molar ratio between hard template and metal ions is 2:1, LaCoO3 samples which own the largest specific surface area went up to 124.14 m2/g, and keep a single perovskite phase. CO catalytic activity experiments show that the bigger the specific surface area of LaCoO3 perovskite catalyst, the lower the light-off temperature and the better catalytic activity.
Keywords: other subjects of material science; mesoporous materials; SBA-15; hard template method; mesoporous perovskite LaCoO3

Title: Theoretical study of thin film deposition within nanometer thickness by PVD

Authors: SONG Taiwei, GAO Weibo, YU Dongdong, FANG Xiang, YANG Guang
PP: 2502-2507
Abstract: In this paper, the deposition of thin film with a thickness of 1-2 nm was realized by traditional physical vapor deposition based on thermo-evaporation and magnetron sputtering. For the thermo-evaporation, controlling of the source evaporation and the motion path of the particles was analyzed. For the magnetron sputtering, the effects of electro-magnetic field, pressure and temperature on the types of particles and motion paths was also analyzed. The ideal deposition equation was built by globally statistic logic. Both of which are useful guideline for the equipment design to realize a deposition thickness of 1-2 nm.
Keywords: material synthesizing and processing techniques; E-beam evaporation; magnetron sputtering; deposition rate

Title: A study on the pores structure and hydrophily of TiO2 coating prepared by micro-arc oxidation in tetraborates

Authors: LI Yaotian, WANG Weiqiang, LIU Zhenfei, QI Min
PP: 2497-2501
Abstract: Using three tetraborates of Li2B4O7, Na2B4O7, K2B4O7 as electrolyte, coatings with micro/nano dual porous TiO2 were formed on the surface of Ti through micro-arc oxidation. The morphology, structure and hydrophily of the coatings were investigated by scanning electron microscope (SEM), X-ray diffraction (XRD) and contact angle measurement, respectively. The results showed that cortex-like slots are formed in all three electrolytic solutions of tetraborates. But morphologies are different in different electrolytic solution. Surface of coating in K2B4O7 electrolytic solution is smooth, that in Na2B4O7 electrolytic solution has a few nano dimples on ridges, while that in Li2B4O7 electrolytic solution has more nano dimples on ridges. The above morphologies and formation mechanism were analyzed, which lays a foundation on further understanding of the mechanism of micro-arc oxidation.
Keywords: surface and interface in the materials; Ti; micro-arc oxidation; micro/nano dual pores; hydrophily

Title: Macroscopic damage influence on the thermal stress distribution in thermal barrier coatings

Authors: HUANG Taihong, SONG Peng, ZHOU Huihui, JI Qiang, LUO Heng, MA Jingtao, LU Jiansheng
PP: 2491-2496
Abstract: During gas turbine blades servicing, blades always formed two kinds of macroscopic pit by high velocity gas erosion and foreign impact. We researched the impact pits and the hole at the edge of blade influence on the thermal stress distribution in this paper. We simulated the thermal stress distribution and changing trend under high temperature by ANSYS. By analyzing the life span of the thermal barrier coatings (TBCs), we found that macroscopic impact pits can change the original thermal stress distribution. The impact pits can expand the maximum tensile stress area at the crest, which is conducive to the generation of cracks and reduce the coatings life. The hole can seriously break the original thermal stress distribution. The entire thermal growth oxide (TGO) is in tensile stress condition and the maximum thermal stress region exists between the TGO and bond course (BC) near the bottom of the hole. The hole severely restricts the thermal barrier coating life.
Keywords: composite materials; finite element method; thermal barrier coatings; thermal stress; coating life

Title: Surface modification of macroporous SiO2-TiO2 ceramic foams via HF-etching and the application in the hydrogenation of commercial polystyrene

Authors: HAN Kaiyue, GUO Wenze, WANG Meng, MENG Chen, CAO Guiping
PP: 2482-2490
Abstract: Hydrogenation of polystyrene (PS) to produce hydrogenated polystyrene, also known as polycyclohexylethylene, is an important polymer modification process to improved heat and UV resistance of PS. Owning to the large size of PS coils and high viscosity of the system, macroporous ceramic foam had good industrial potential. However, the ceramic foam usually possessed low specific surface area (<1 m2/g) due to high-temperature sintering. In this paper, the SiO2-TiO2 ceramic foam (STCF) was prepared using synthetic template replica method, and further HF-etching was applied to increase the specific surface area. The effect of HF etching on the mechanical and structural properties of STCF was investigated by strength test, scanning electron microscope (SEM), energy dispersive spectroscopy (EDX) and X-ray diffraction (XRD), respectively. By optimizing the treatment time, HF-etching could remove the SiO2 on the surface of ceramic foam sample while the SiO2 inside the struts was remained, leaving interspaces on the etched ceramic foam struts (0.5-1.0 μm). The obtained 0.1STCF-HF5 with increased specific surface area could facilitate the dispersion of Pd. The Pd-supported HF-etched STCF catalyst exhibited enhanced hydrogenation activity with negliable internal diffusion of PS coils.
Keywords: composite materials; ceramic foam; polystyrene hydrogenation; HF-etching

Title: The magnetic and transport property of Cr(Mn)xFe3-xO4/ZnO composite films

Authors: LI Peng, CUI Wenyao, BAI Haili
PP: 2474-2481
Abstract: Fully epitaxial all oxide heterostructures Cr(Mn)xFe3–xO4/ZnO were fabricated by reactive sputtering on c-Al2O3. The microstructure and chemical component of the films were systematically investigated by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-ray photoelectron spectroscopy (XPS). A quantum design physical property measurement system (PPMS) was introduced to investigate the transport properties of the samples. Structural analyses reveal that the Cr(Mn)xFe3–xO4 films have a spinel structure. The Cr(Mn)xFe3–xO4 and ZnO films on c-Al2O3 are fully epitaxial, where the epitaxial relationship is Cr(Mn)xFe3-xO4(111)||ZnO(0002). XPS shows that γ-Fe2O3 is absent in the Cr(Mn)xFe3–xO4 films, and the valences of Cr atom and Mn atom are mainly +3 and +2, respectively. The transport mechanism across the Cr(Mn)xFe3–xO4/ZnO interface is thermal emission /diffusion at low temperatures. The Schottky barriers of the ZnO based heterostructures are 0.362 eV (Cr) and 0.360 eV (Mn), respectively. The spin polarization of Cr(Mn)xFe3–xO4 at 30 K is 56.3% (Cr) and 43.8%(Mn), respectively.
Keywords: low-dimensional inorganic nonmetallic materials; epitaxial films; heterostructure; spin polarization

Title: Preparation mechanism and amplitude manipulation of wavy polystyrene fibers in electrospinning

Authors: WANG Dexin, CHEN Zhihong, WANG Yilong, LI Shanlin, ZHAO Suling
PP: 2466-2473
Abstract: In this paper, we investigated the morphology change and formation mechanism of wavy microfibers produced in electrospinning by taking polystyrene (PS)/dimethylformamide (DMF) solution as an example. The effect of electrospinning parameters including voltage and nozzle-to-collector distance, on the amplitude of wavy fibers was explored. Several kinds of arrays consisting of wavy microfibers was prepared. Our results showed that with the increase of collector speed, PS microfibers experienced the conversion in morphology from translated coiling to W-shaped microfibers, then to wavy microfibers, and finally to straight fibers. Further analysis on the relationship between the amplitude and collector speed indicates that the conversion from wavy fibers to straight fibers follows the Hopf bifurcation, i.e. the nonlinear perturbation in the direction perpendicular to the movement of collector generates Hopf bifurcation with O(2) symmetry and initiate the formation of wavy fibers. The conversion between wavy fiber and W-shaped fiber may be induced by the change in the kinematic mode of perturbation in the longitudinal and transverse direction to the movement of collector. Wavy fiber with maximum amplitude located at the position where the fiber changed from W-shaped fiber into wavy fiber. The value of maximum amplitude and critical collector speed increased with the increase of voltage and nozzle-to- collector distance. We managed to produce arrays consisting of uniaxially aligned, 90° cross-stacked and 45° cross-stacked wavy fibers, which are potential candidates to prepare stretchable electronics.
Keywords: organic macromolecule materials; preparation mechanism; Hopf bifurcation; amplitude manipulation; electrospinning; wavy polystyrene fibers

Title: Fabrication and electrochemical properties of polyaniline nanowires intercalated graphene composites

Authors: YU Pingping, ZHAO Xin, ZHANG Qinghua
PP: 2460-2465
Abstract: Polyaniline/microwave assisted graphene (PANI/MEGO) composites were synthesized by in situ polymerization, and the mass ratios of PANI:MEGO were 98:2 (PANI/MEGO=2%) and 90:10 (PANI/MEGO=10%). The structural and morphological characterizations were performed by field emission scanning electron microscope (FESEM) and X-ray diffraction (XRD) analysis. The results show that aniline cation was formed in the acid solution and intercalated into the interlayer of multilayer graphene, and then in situ polymerization of PANI enhances the distance between the graphene sheets. PANI/MEGO=10% shows a higher specific capacitance (660 F·g-1) and smaller charge transfer resistance than PANI/MEGO=2% as a supercapacitor electrode. The attractive charcateristics showed in these composites make them potential candidates for supercapacitors.
Keywords: organic macromolecule materials; supercapacitors; polyaniline; graphene

Title: Preparation and preliminary study of the siRNA-loaded polymer nanocapsules

Authors: ZHOU Junhui, YANG Zheng, DENG Liandong, DONG Anjie
PP: 2454-2459
Abstract: In this paper, a series of amphiphilic copolymers MPEG-b-P bearing (2,4,6- trimethoxybenzy-lidene-1,1,1-tris(hydroxymethyl) ethane methacrylate (TTMA) and 2-di(isopropylamino) ethyl methacrylate (DPA) with different feed ratios were obtained by reversible addition-fragmentation chain transfer (RAFT) radical copolymerization. By adjusting the content of DPA, the hydrolysis rate of pH sensitive monomer TTMA in the polymer was regulated. The siRNA-loaded polymer nanocapsules were constructed by double emulsion solvent evaporation method. The experimental results show that the size of the nanocapsules is uniform and the toxicity is lower, which would make a promising delivery carrier.
Keywords: organic macromolecule materials; nanocapsules; siRNA; TTMA; double emulsion solvent evaporation method

Title: Effects of quenching and tempering process on microstructure and properties of Q345B casting

Authors: WANG Biao, CHEN Shifu, GAO Han
PP: 2448-2453
Abstract: This paper mainly discusses the effects of heat treatment process of Q345B steel at 900-1 060℃ quenching +450℃ tempering process on the performance of steel. After heat treatment, the steel samples of different treatments were taken to observation and test to get the statistical analysis of test results by changing heat treatment on the properties of the steel. Results show that the quenching process enhance the strength and hardness of the steel significantly. After tempering at 450℃, the plasticity and toughness of steel has also been picked up. The steel has good corrosion resistance when the quenching at 980-1 020℃. Considering the strength, hardness, plasticity and toughness, and the heating temperature, production practice, the heat treatment process of quenching at 940℃+450℃ tempering of steel samples, can make the steel obtain excellent comprehensive properties, which is of great economic significance and practical significance.
Keywords: metallic materials; Q345B steel; quenching and tempering process; microstructure and properties; the optimum process

Title: Effects of homogenization and rolling parameters on microstructure and mechanical properties of ZK60-1.0Y alloy sheet

Authors: YAN Hongge, CHEN Jihua, YU Haiyang, SU Bin
PP: 2440-2447
Abstract: In this paper, the effects of homogenization and rolling parameters on microstructure and mechanical properties of the as-rolled ZK60-1.0Y alloy plates are investigated by optical microscope (OM), transmission electron microscope (TEM), tensile testing and fracture analysis. The results show that the plates prepared by the homogenized ingots with the rolling temperature of 400℃ and the rolling strain rate of 9.1 s-1 exhibit the best combination of mechanical properties, with ultimate tensile strength, yield strength and elongation of 335 MPa, 254 MPa and 25.5%, respectively. The extent of dynamic recrystallization (DRX) increases with the higher rolling temperature, but the DRX grains are coarser. With the rolling strain rate between 7.1 s-1 and 16.2 s-1, the DRX grains become finer and the volume fraction of DRX exhibits an increase at first and then a reduction with the higher rolling strain rate.
Keywords: non-ferrous metal and alloy; magnesium alloy; high strain rate rolling; Mg-Zn-Zr alloy; microstructure; mechanical properties

Title: Research progress in semisolid slurry preparation technologies for magnesium and aluminum alloys

Authors: MO Wenfei, LIU Wencai, WU Guohua, WANG Cunlong, DING Wenjiang
PP: 2427-2439
Abstract: Magnesium and aluminum are very attractive for realizing lightweight in structural materials, and semisolid forming is a promising way to improve both room temperature and elevated temperature mechanical properties of these alloys. Rheo-forming has been the main tendency of semisolid forming as for its no need for preparing billets and reheating them. The key technique in rheo-forming is to obtain good semisolid slurry, which contains non-dendrite microstructure. In this paper, methods on preparing semisolid slurry of magnesium and aluminum alloys are divided into two categories, namely the contact and the non-contact. Mechanisms of obtaining the non-dendrite microstructure are clarified respectively, and some related research achievements in recent years are also introduced here.
Keywords: non-ferrous metal and alloy; rheo-forming; review; magnesium alloy; aluminum alloy; semisolid slurry

Title: Present situation and development of sheet metal incremental forming technology

Authors: SANG Wengang, WANG Huabi
PP: 2420-2426
Abstract: Sheet metal incremental forming technology is a new kind of plastic forming technology. It can quickly and economically produce the complex shapes of sheet directly from the computer aided design (CAD) data without the need for costly die and can be applied to the sample preparation, single piece and small batch production. This paper introduced the principle of sheet metal incremental forming technology, features and process route, and systematically summarized and analyzed the domestic and foreign development present situation from these aspects such as forming mechanism, forming performance, forming accuracy, special parts forming, numerical simulation and the forming surface quality. It also introduces the application of incremental forming and equipment. Finally the problems of sheet metal incremental forming technology and the future research direction are pointed out.
Keywords: metallography; sheet metal; review; incremental forming; dieless forming; present situation

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