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ISSN 1674-2850
CN 11-9150/N5
 
Current Issue
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May 15,2011
Volume 4,Issue 9
Pages -
Subject Area:Glass and Amorphous Inorganic Metallic Materials,Foundational Subject in Materials Science,Composite Materials
 
Title: Effects of technological system on foamed properties of foam glass
Authors: SHEN Qingfeng
PP: 855-860
Abstract: Foam glass was prepared by sintering process, using powder of waster glass as main raw material and graphite as foaming agent. In order to optimize the prepared technological parameters, the influence of parameters, such as foaming temperature, holding time, amount of foaming agent, etc, on the apparent structure, density, pore diameter and distribution has been studied. The result of experiments showed that when the foaming temperature is 880℃, the pores are uniform and the amount of connected pores is reduced; the pore diameters increase and are more homogeneous for holding 10 minutes; adding 2% graphite foaming agent can obviously increase the porosity and the diameter, as well as improve the foaming properties; ball-milling for 2 hours can mix the raw material well, and improve the pore structure.
Keywords: glass and amorphous inorganic metal materials; foam glass; optimize; foaming temperature; holding time; graphite foaming agent
 
Title: Tensile and flexural properties of graphite prepared by extrusion moulding at elevated temperatures
Authors: ZHANG Chengyu, QIAO Shengru, LI Mei, HAN Dong, HE Xubin
PP: 850-854
Abstract: The tensile and flexural properties of the graphite made by extrusion molding were investigated at high temperatures. The fracture morphology was surveyed by a scanning electron microscope. The results show that the strength and modulus increase with the temperature up to 2 000℃. The radial properties of the material are apparently higher than the axial properties, showing the anisotropic character of the graphite. It can be explained by the different orientation of basal planes of the graphite crystals. The flexural properties are higher than the tensile properties. The phenomena indicate that the graphite possesses higher resistance to stress gradient than uniform tensile stress.
Keywords: material science;graphite; tensile strength; tensile modulus; flexural strength; flexural modulus
 
Title: Growth and characterization of one-dimensional CdS nanostructures on the ITO substrate
Authors: ZHU Junjun, FAN Guoqiang, XU Zaiquan, TANG Jianxin, LI Yanqing
PP: 845-849
Abstract: For the application of CdS nanostructures in optoelectronic devices, it is desirable to synthesize the materials on the indium tin oxide (ITO) glass substrate. In this paper, the orderly and well crystallized CdS nanostructures on the ITO glass substrate are demonstrated via Au nanoparticle-assisted thermal vapor deposition process. The morphology of CdS nanostructures is optimized by controlling the growth parameters in terms of the flow rate of carrier gas, pressure and substrate position in the furnace, etc. The growth mechanism of CdS nanostructures on ITO substrate is analyzed based on the characterization of scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM) and energy-dispersive X-ray spectroscopy (EDX).
Keywords: inorganic nonmetallic material; one-dimensional CdS nanostructures; ITO; growth mechanism
 
Title: Room-temperature photoluminescence from ZnO/ZnMgO single quantum well
Authors: WNAG Yanjie, ZHANG Shizhu, HE Haiping, YE Zhizhen
PP: 841-844
Abstract: ZnO/ZnMgO single quantum wells (SQWs) with different well layer thickness have been grown on Si (111) substrates by pulsed laser deposition (PLD). Compared with the ZnO single layer, room-temperature photoluminescence resulting from the well regions exhibits a blueshift. Also, the blueshift increases with the decrease of the well thickness. The well layer thickness dependence of the emission energy was calculated by a simple theoretical model and compared with the experimental data. The observation of quantum confinement effects at room temperature suggests the sharp interface and good crystal quality of the grown SQW.
Keywords: materials physics and chemistry; ZnO/ZnMgO single quantum well; photoluminescence; quantum confinement effects
 
Title: The surface wettability and structure of wheat straw treated by enzyme
Authors: LIU Yanping, ZHANG Yang, JIANG Hua, JIA Chong, ZHOU Zhaobing
PP: 836-840
Abstract: In this paper the surface wettability and structure of wheat straw treated by enzyme were investigated under different conditions. It was found that the contact angle of wheat straw decreased greatly under the optimum condition, treatment temperature 45℃, treatment time 6 h, pH value 5.0, enzyme usage 205.0 IU·g-1 through studying the influence of xylanase and treatment temperature 50℃, treatment time 12 h, pH value 7.5, enzyme usage 20 g·L-1 through studying the influence of lipase treatment condition on the surface property of wheat straw. The micro structure of wheat straw treated by enzyme was investigated with scanning electron microscope (SEM). The results indicated that the micro structure of outer surface for the wheat straw treated by enzyme was changed, the cellulose and lignin were activated and the wax-layer of wheat straw was dissolved. This is good for increasing its gluing ability.
Keywords: wood science and technology; enzyme; wheat straw; surface wettability; surface structure
 
Title: Thermal effects of Fe3O4 nanoparticles in liquid crystals under high-frequency electric field
Authors: LI Zhe, CAO Hui, YANG Chaoyong, YANG Huai, CUI Xiaopeng, LIU Fang
PP: 830-835
Abstract: With the addition of Fe3O4 nanoparticles into SmA-N*-LC, a SmA-N*-LC/Fe3O4 nanoparticles composite was prepared. The thermal effect of Fe3O4 nanoparticles in liquid crystal under high-frequency electric field was studied. The results showed that the voltage, electric frequency and content of Fe3O4 nanoparticles affected its thermal effects in the liquid crystals.
Keywords: organic chemistry; liquid crystal; Fe3O4 nanoparticles; thermal effect
 
Title: Exploratory experiment on detached solidification in gravity condition
Authors: LI Zhen, WANG Fei, PENG Lan
PP: 826-829
Abstract: This paper presents a way letting the crystals separated from the container wall, via gathering of bubbles on the container wall to form gas gap, explores and provides new method for detached solidification in gravity condition. Oil is used to carry out experiment of detached solidification in gravity condition and obtain better results. Furthermore, the effects of the bubble quantity, container size and other factors on detached solidification are analyzed.
Keywords: material preparation; gravity; gas gap; detached solidification; experiment
 
Title: Effect of annealing atmosphere on ferromagnetism of Zn0.92Co0.08O thin films prepared by pulsed laser deposition
Authors: HE Qiong, WANG Hao, WANG Hanbin, WANG Xina, ZHANG Jun
PP: 820-825
Abstract: Zn0.92Co0.08O thin films were fabricated on Si(100) and quartz glass substrates by pulsed laser deposition using a ZnCoO ceramic target. The structural and magnetic properties of the films were characterized by field emission scan electronic microscopy (FE-SEM), X-ray diffraction (XRD), X-ray photoemission spectroscopy (XPS), UV-visible transmission spectrum and vibrating sample magnetometer. Substitutional doping of Co2+ in ZnO lattice was demonstrated in the films. The as-prepared Zn0.92Co0.08O thin films displayed room temperature ferromagnetism with saturation magnetization of 6.3 emu/cm3. After annealing the films under vacuum, the saturation magnetization of the films increased to 7.0 emu/cm3. On the contrary, the saturation magnetization decreased to the value of 4.2 emu/cm3 after the film was annealed under oxygen atmosphere. Hall effect measurements further indicated that an oxygen vacancy mediated exchange mechanism should be responsible for ferromagnetic ordering in the diluted magnetic semiconductor films.
Keywords: microelectronics and solid state electronics; diluted magnetic semiconductor; ZnO; Co-doping; magnetic property; defect
 
Title: Synthesis and growth mechanism of helical carbon nanofibers from amine flames
Authors: LIAO Lingmin, PAN Chunxu
PP: 813-819
Abstract: Three liquid amine fuels were used for growing carbon nanofibers (CNFs) from nickel catalyzers in flames. The morphologies and microstructures of the combustion products were characterized by using field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HR-TEM). It was found that rope-like helical CNFs of low pitch and spring-like nano-coils CNFs of high pitch were obtained when the nickel nitrate catalyst was used, while the straight filament-like CNFs were produced when the plated Ni nanocrystalline catalyst was used. The growth mechanism for the rope-like helical CNFs might be the combining effects of the catalyst particles, carbon content and combustion heat of the fuels. And the growth of the spring-like nano-coils was coarsely related with molecular chain structures for different amine fuels. In addition, many defective sites were observed upon the sidewall of the helical CNFs, which might be induced by the nitrogen element contained in the amine fuels.
Keywords: nanometer materials; carbon nanofibers; flames; amine; helical
 
Title: Study on the microscopic flow behavior of RTM
Authors: HUANG Yuxia, XIE Guilan, CAO Weinan, REN Baichun
PP: 809-812
Abstract: Based on flow characteristics of resin in reinforcing material, a mathematical model is derived by fluid dynamics, the flow front is tracked by means of the volume of fluid (VOF) method, the influences of parameters on filling process of resin transfer moulding (RTM) are analyzed. The results show that the greater the filling rate is and the lower the cellosilk’s radius is, the steeper the flow front is, the more easily the bubbles flaw is formed. But it is not changed by different viscosity.
Keywords: materials processing engineering; resin transfer moulding; microscopic flow; flow front; numerical simulation
 
Title: Structure and properties of isotactic polypropylene with two-scale reinforcements
Authors: CHEN Yanhui, YANG Haoran, ZHANG Zhengchi, TANG Jianhua, LI Zhongming
PP: 802-808
Abstract: The isotactic polypropylene (iPP) composite with two-scale reinforcement structure, i.e., nano-scale molecular orientation structure (shish-kebab structure) and micron-scale glass fiber (GF), was fabricated by an oscillatory shear injection molding (OSIM) technology. The results of wide-angle X-ray diffraction and small-angle X-ray scattering (SAXS) measurements indicated that the combined effect of oscillatory shear flow and GF network gave rise to a high fraction of shish-kebab structures in the OSIM samples. The OSIM samples with the two-scale reinforcement structure had enhanced tensile strength and improved impact strength, compared with the GF filled iPP samples prepared by conventional injection molding (CIM). However, the tensile strength and impact toughness of the OSIM iPP/GF composites were comparable to that of the OSIM iPP samples. This is because partial self-reinforced shish-kebab structures were replaced and weak interface was introduced along with the introduction of GF.
Keywords: materials processing engineering; glass fibers; mechanical properties; shish-kebab structure; injection molding
 
Title: Structural and optical properties of multilayer InAs/InGaAs quantum dots on ultra-thin InGaAs strained layer
Authors: ZHANG Chunling, YAO Jianghong, XU Bo
PP: 798-801
Abstract: Six layer InAs quantum dots (QDs) were grown on 50 nm InGaAs strained layer. By analyzing the strain between different layers, combining real time inspection by reflection high-energy electron diffraction (RHEED), the surface morphology measurement after growth, and the 77 K photoluminescence (PL) spectrum, it was found that the dislocations formed between strained layer and substrate can affect the distribution of QDs, but the optical characteristic is damaged by the dislocations at the same time.
Keywords: materials physics and chemistry; quantum dots; molecular beam epitaxy; stress; photoluminescence spectrum
 
Title: Effect of annealing treatment on the microstructure and properties of TiSixNy superhard coatings
Authors: LU Yonghao, WANG Junping, LI Mingxing, TAO Shilong
PP: 791-797
Abstract: In this study, a series of TiSixNy superhard coatings with different Si contents were prepared on M42 steel substrates using 2 Ti and 2 Si targets by reactive magnetron sputtering at 500℃ in nitrogen-argon mixed atmosphere. These samples were subsequently vacuum-annealed at 500, 600, 700, 800 and 900℃, respectively. X-ray diffraction (XRD), microindenter and scratch tester were applied to investigate the microstructure, mechanical behaviors and adhesion property of as-deposited and annealed samples. The results indicated that annealing treatment below 900℃ played a little role in microstructure and mechanical behaviors of the coatings, however greatly affected the microstructure and mechanical behaviors of steel substrates. The film-substrate adhesive force was slightly increased, followed by abrupt decrease with increasing annealing temperature. Its value got to the maximum at 600℃. The friction coefficient was slightly decreased with increase of Si content. Its value varied in the range of 0.352-0.404. Annealing below 900℃ had less effect on the friction coefficient.
Keywords: materials physics and chemistry; TiSixNy; nanocomposite; annealing; microstructure; adhesive force
 
Title: Modifying effect of rapidly solidified Al-5Ti-1B and Al-10Sr master alloy on ZL109 alloy
Authors: CUI Chunxiang, WANG Xueqin, LIU Shuangjin, ZHANG Yanjie, GU Cunshuai, SUN Jibing
PP: 786-790
Abstract: This paper deals with the modifying effect of rapidly solidified Al-5Ti-1B and Al-10Sr master alloy on ZL109 alloy. Al-5Ti-1B and Al-10Sr master alloys were fabricated out in rapid solidification process. While the cooling rate was about 105-106℃/s, the thin silk ribbon thinning inoculant was obtained. The Al-5Ti-1B and Al-10Sr master alloy, as the shape of thin ribbon and the general block-like were added into the ZL109 alloy, respectively, and the effects of alloy modification were compared with each other. The experimental results showed that the addition of nanometer Al-5Ti-1B and Al-10Sr could refine the microstructure of ZL109 alloy significantly, thus the hardness, wear resistance and tensile strength increasing obviously. The addition of Al-10Sr into ZL109 alloys as a modifier could result in the morphology transition of eutectic silicon from coarse plate-like or acicular to fine fibrous.
Keywords: metal matrix composites; rapid solidification; aluminium alloy; inoculant; mechanical properties
 
Title: Preparation and application of hollow microspheres
Authors: MEI Xiao, LI Najun, XIA Xuewei, XU Qingfeng, GE Jianfeng, LU Jianmei
PP: 779-785
Abstract: Hollow microspheres are one kind of new material in nano-or micro-size with core-shell special structure whose core is hollow while the shell is bestrewed with pores. In order to prepare such kind of materials with special structure, much methods had been used in many areas, such as use porous alumina, mesoporous silica and others as hard template or micelles, vesicles as soft template to prepare hollow microspheres, and high-temperature melting method, spray method for industrial production. Several methods for preparing this material were reviewed. And the applications in drug carrier, photocatalysis and photoelectrical materials have also been introduced.
Keywords: composite materials; hollow microspheres; reviews; preparation; application