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ISSN 1674-2850
CN 11-9150/N5
 
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November 30,2009
Volume 2,Issue 22
Pages 2353-2450
Subject Area:Composite Materials
 
Title: Study on preparation of carbon fiber reinforced Nylon 6 composite
Authors: LI Chunhua, SONG Guojun, YANG Shujing, YANG Chao, SUN Wei
PP: 2446～2450
Abstract: Carbon fiber-reinforced composites were prepared successfully by twin-screw extruder. Microstructure and mechanical properties of carbon fiber-reinforced plastics (CFRP) were studied. Scanning electron microscope photograph of carbon fiber treated by nitric acid indicated more legible grooves than that of untreated one. It shows good matrix-carbon fiber adhesion between the treated carbon fiber (CF) with fracture surface morphology and polymide 6 (PA6). The mechanical property of composite is enhanced compared with pure PA6. Especially, tensile strength and tensile modulus are enhanced by 33% and 50% respectively. Differential scanning calorimetry (DSC) curves of sample illustrate CF plays a part of heterogeneous nucleation in composite.
Keywords: functional organic polymer material; carbon fiber; nitric acid oxidation; interfacial adhesion; twin-screw extruder
 
Title: Optimization and analysis of the microwave absorption properties of carbon blacks
Authors: WANG Zhongzhu
PP: 2441～2445
Abstract: The relationship between the complex permittivity and frequency was represented by least square method, the microwave absorption properties of the carbon blacks coated on the metal were calculated theoretically, furthermore, the optimal coat thickness relating to the optimal microwave absorption was gained through least square method. The complex permittivity between 1 and 10 GHz can be described by Debye equations, which is corresponding with the data gained from least square method, it shows that the least square method is the effect way to investigate the microwave absorption properties of the absorbers.
Keywords: microwave absorption material; carbon black; least square method; optimal thickness; Debye polarization-relaxation equation
 
Title: Study on the preparation and electrical properties of Sr2K0.1Na0.9Nb5O15 lead-free piezoelectric ceramics
Authors: WEI Lingling, LIU Zhongshan, YANG Zupei
PP: 2435～2440
Abstract: In this paper, lead-free Sr2K0.1Na0.9Nb5O15 ceramics were prepared by conventional solid state method. The effects of sintering temperature on phase structure, microstructure and electrical properties of Sr2K0.1Na0.9Nb5O15 ceramics were investigated. The XRD analysis results showed that the obtained ceramics were all pure tungsten bronze structure Sr2K0.1Na0.9Nb5O15 when the sintering temperature was from 1 300 to 1 360℃. With increasing the sintering temperature, the relative density and electrical properties of the obtained ceramics all increased firstly, and decreased after reaching the maximum. The ceramics sintered at 1 340℃ achieved uniform grain size, higher density and better properties, which were as follows: εr =1 221, tanδ=0.015 9, and TC=270℃.
Keywords: functional materials; lead-free piezoelectric ceramics; microstructure; piezoelectric properties; dielectric properties
 
Title: Upconversion luminescence of Er3+ and Yb3+ codoped GdNbO4 nanocrystals
Authors: PAN Yuexiao
PP: 2431～2434
Abstract: Er3+/Yb3+ co-doped monoclinic GdNbO4 nanocrystals have been synthesized by a combustion method. The crystal structure and microscopic shape were explored by X-ray diffraction (XRD) and transmission electron microscopy (TEM) respectively. The GdNbO4 nanocrystals obtained by combustion method showed uniform particles with size about 60 nm. The upconversion luminescence and infrared emission spectra were investigated. The optimum concentration of Er3+ and Yb3+ are 5%~7% (in mol ratio) and 10%~20% (in mol ratio) respectively. The dependence of the upconversion luminescence intensity on pump power confirmed that the upconversion luminescence in Er3+/Yb3+ co-doped monoclinic GdNbO4 nanocrystals was produced by two-photon excited-state absorption process.
Keywords: inorganic chemistry; rare earth ions; niobates; nanocrytals; upconversion luminescence
 
Title: Synthesis and growth mechanisms of Zn/ZnO dendritic structures
Authors: ZANG Chunyu, ZANG Chunhe, JIA Zhixu, FANG Shijie, SI Zhenjun, WANG Xinwei
PP: 2427～2430
Abstract: Zinc deposits with dendritic frameworks were obtained by thermal Zn powder method. The zinc dendrites were composed of submicron-sized branches with the same shape and structure, and each submicron-sized branch was made up of numerous nanodisks with a regular hexagonal shape. The nanodisks crept along the three crystal axis orientations and fused together to form the stems of zinc dendrites. By thermal oxidation, Zn/ZnO core-shell structures were formed. The shapes of the dendrites were not only decided by crystallographic and thermodynamic properties, the crystal growth kinetics should be also considered, as well as the effect of the quantity of heat and mass transport. The dendritic growth process was a release process of the latent heat of solidification. The nucleation and growth mechanisms were also investigated, such as 2D growth mechanism including face diffusion and step growth mechanisms, as well as 1D linear growth mechanism.
Keywords: non-metallic inorganic material; ZnO; dendrites structure; growth mechanism
 
Title: Hydrothermal synthesis of graphitic carbon nitride
Authors: LIU Wei, XU Dan, ZHANG Jian, ZOU Guangtian
PP: 2422～2426
Abstract: Hydrothermal synthesis method taking cyanuric chloride (C3N3Cl3) and sodium azide (NaN3) as predecessors was used to prepare graphitic carbon nitride. The samples were characterized by using elemental analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) in parallel. Elemental analysis gave internal content of various elements in the samples and the ratio among the elements. XRD further confirmed the synthetic samples were crystalline graphitic carbon nitride. FTIR spectrum and XPS analysis gave main bonding types between nitrogen and carbon atoms in the synthesized graphitic carbon nitride.
Keywords: non-metallic inorganic material； graphitic carbon nitride; hydrothermal synthesis; X-ray diffraction; X-ray photoelectron spectroscopy
 
Title: Fabrication of ZnO-based super hydrophobic surfaces and their water-adhesion properties
Authors: LI Tao, LIU Changsong, ZHANG Qiang, LI Zhiwen
PP: 2417～2421
Abstract: ZnO films with rough micronanostructures were fabricated by a low-temperature liquid method. （Heptad-ecafluoro-1,1,2,2-tetrapydrodecy-1-trime-thoxysilane, FAS） was used to modify the ZnO micronanostructure surface by self-assembly technology. This study focused on the wettability and water adhesion property of ZnO-based films before and after FAS modification. After they were modified by FAS, the water contact angle increased from 139.5° to 172.9°, indicating a transition of wettability from high-hydrophobic to super-hydrophobic. Also, the water adhesion changed from high to almost zero. Such excellent super hydrophobicity (high water contact angle and low water adhesion) resulted from the binary effect of the roughness of ZnO micronanostructures and the low surface energy of FAS. Using the significant difference of water adhesion on the two superhydrophobic surfaces (ZnO films before and after FAS modification), water micro-droplets can be transfered between these two surfaces without any mass loss. It is expected to apply these surfaces in microfluidic devices.
Keywords: non-metallic inorganic material; ZnO; micronanostructure; wettability; super hydrophobic; microfluidic device
 
Title: The performance test of new composite wax powder based on selective laser sintering
Authors: TIAN Fang, WANG Pengcheng, ZUO Tanghai, ZHANG Liming
PP: 2412～2416
Abstract: In this paper, the performance tests of new composite wax powder were discussed based on national standard GB/T1040-92 and technological requirements of investment casting, which involve melting point, thermal distortion, melt index, ash content and others. The physical property, processing property of selective laser sintering and lost wax casting of the wax powder were tested emphatically. Through these tests, the performance parameters of wax powder could be compared, supplemented and perfected for improving the selective laser sintering process and the post-treatment process of sintered parts used in investment casting. The results showed that melting point is 79.5℃, density is 0.915 g/cm3, tensile strength is 4.8 MPa, temperature of thermal distortion is 40.1℃, melt index is 6.5 g/10 min, Vicat softening point is 49.5℃ and ash content is 0.367%. As a conclusion, this wax powder can be used for selective laser sintering and investment casting.
Keywords: composite material; performance test; selective laser sintering; investment casting
 
Title: Research on B4C/Al-AlN composites prepared by reactive melt infiltration
Authors: WENG Zhe, MA Nangang
PP: 2407～2411
Abstract: Through infiltrating molten Al into B4C-BN porous preforms, B4C/Al-AlN composites were prepared by reactive melt infiltration. The microstructures and phases of the composites were investigated by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The chemical reaction happened during infiltration process was discussed. The results indicate that AlN is the only product in the infiltration process when B4C and BN react with Al. Due to the three-dimensional interconnected structure of the porosity in preforms, an interpenetrating network of B4C phase and Al phase results, and the AlN particles, with high thermal conductivity, exist in Al phase evenly. That structure will be conducive to improving thermal conductivity of composites.
Keywords: composites; B4C/Al-AlN; reactive melt infiltration; electronic packaging materials
 
Title: Research of mullite/epoxy resin nano-composites used in electronic packaging field
Authors: WANG Fengqing1, QIANG Yinghuai1, ZHAO Yuejian1, JIA Zhiyong
PP: 2402～2406
Abstract: Nano-mullite coated with titanate was added to epoxy resin(EP). With mechanical mixing and method of ultrasonic dispersion, mullite/epoxy resin nano-composite was prepared. On the basis of getting its best addition and its tensile properties being much better than pure epoxy resin, the paper further described the new material s thermal strength property, linear expansion coefficient, thermal conductivity, volume resistivity, dielectric constant and water absorption performance. It was found that the new material s performance which were tested in this paper could meet the require of the electronic packaging material s. The new material was expected to replace the existing high cost epoxy composites in the field of electronic packaging who can be applied in.
Keywords: composite material; electronic packaging; nano-mullite; epoxy resin
 
Title: Microstructure characterization of carbon microspheres and the study of their electrocatalytic activities
Authors: DU Wen，LIU Hong，GUO Qiaomei，WANG Xiaomin，XU Bingshe
PP: 2395～2401
Abstract: Based on carbon microspheres(CMS) being prepared by chemical vapor deposition (CVD) method, Pt/CMS composites with different Pt loadings as 10%, 20% and 30% were prepared via impregnation-reduction method. The samples were characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and X-photoelectron spectroscopy (XPS). It showed that Pt/CMS composites took on narrow diameter distributing, with the diameter of about 300 nm. The Pt particles possessed the high uniformity and good dispersity, whose average size in the range of 4～5 nm. XRD and XPS detections showed that Pt particles existed mainly in the metallic state. The methanol electrooxidation behaviors of Pt/CMS (10%, 20% and 30%) and Pt/Vulcan XC-72 (20%) in acid solution were evaluated by cyclic voltammetry (CV). The result indicated that Pt/CMS had the better electrochemistry performance than Pt/Vulcan XC-72; Pt particles became serious aggregation in Pt/CMS with 30% Pt loading.
Keywords: composite material; Pt/CMS composites; microstructure characterization; methanol electrooxidation
 
Title: Study on preparation and characterization of nano-SiO2 PEC/hybrid materia
Authors: WANG Lingyuan, WANG Yao, TANG Jianguo
PP: 2390～2394
Abstract: In this paper, low-molecular-weight polyethylene glycol (PEG) was grafted onto the surface of nano-silica particles by a two-step process. The composite structure was characterized by (Fourier transfrom infra-red, FT-IR) spectroscopy, X-ray photoelectron spectrum (XPS), differential thermal analysis (DTA), thermogravimetry analysis (TGA) and transmission electron microscope (TEM). The peaks for methylene group of PEG appeared at 1 354, 1 457 and 2 870 cm-1 in FI-IR. The XPS result also indicated that the —CH2— structure existed in the composites. As showed in the DTA and TGA figures, the organic structure decomposed at 357℃ and lost about 45% weight. So it can be calculated that the grafting percentage is about 45%.
Keywords: composite material; hybrid materials; surface grafting; nano-composite; hybrid materials
 
Title: Numerical analysis of interlaminar stress on symmetric angle-ply laminated rectangular plate
Authors: FAN Jianping, PAN Zuxing，LIU Jianhuang
PP: 2386～2389
Abstract: The paper focuses on the investigation of interlaminar stress characteristics of the symmetric angle-ply laminated rectangular plates ［±θ ］s under uniaxial tensile loading. 3D solid element Solid46 is used in the commercial finite element software ANSYS for establishing geometric modeling and numerical analysis with linear-elastic anisotropic assumption in single ply. The interlaminar stress distribution near the edge of the typical symmetric angle-ply laminated plates ［±25］s is discussed. The results show that the normal stress is maximum at corner points, while shear stress is relatively high at free edge and decreases at corner points. The effect of off-axis angle. on interlaminar stress is studied finally, and the relationship between maximum interlaminar stress and layer angle is achieved.
Keywords: composite material; laminates; interlaminar stress; numerical analysis; ANSYS
 
Title: Preparation of SBS-g-AA/SBS-g-PAM bipolar membrane and its application in paired electrosynthesis of glyoxylic acid
Authors: HUANG Xuehong，LIN Pu，KE Shengbo，ZHENG Ruonan，CHEN Zhen
PP: 2378～2385
Abstract: SBS-g-AA/SBS-g-PAM bipolar membrane (SBS BPM) was prepared by SBS doped acrylic acid (AA) through free radical grafting reaction as the anode membrane, and SBS doped acrylamide (AM) through Mannich reaction as the cathode membrane, respectively. The component and morphology of SBS BPM were characterized by infrared (IR) spectra and scanning electron microscope (SEM), and the effects of some factors on swelling degree of the membrane. When the grafting degree of trialkylamine SBS-g-PMA was 23.8%, the water contenting rate, contact angle, ion exchange capacities of the cathode membrane were 51.1%, 53.1 1.15mmol/g, respectively. The experiment used SBS BPM as a separator between the cathode and anode chamber in the electrolysis cell to produce glyoxylic acid in pairs. The experiment results show that the mixture of saturation oxalic acid and HCl as cathode electrolyte, the mixture of 10% glyoxal and 10% KBr as anode electrolyte, Pb as cathode, graphite as anode, the cathode and anode chamber average current efficiency were 76.8% and 73.4% respectively at the room temperature during the current density was 18.8 mA/cm2.
Keywords: foundational discipline in materials science; styrene-butadience-styrene triblock copdymer; trialkylamine SBS-g-PAM; graft copolymer; bipolar membrane; water contenting rate; ion exchange capacity
 
Title: Study on synthesis of carbon nanofibers by chemical vapor deposition using KI catalyst
Authors: JIA Mingming, ZHANG Yongheng
PP: 2373～2377
Abstract: Most catalysts used in preparing carbon nanofibers by chemical vapor deposition are transition metals, such as Fe, Co and Ni. Purifying the carbon nanofibers must use strong acids if Fe, Co and Ni metals are used as catalysts. This process costs a lot and some impurities can not be removed easily. At the same time, the structure of nanofibers can be destroyed easily. To solve the above problem, in this study, the carbon nanofibers with helical, linear and hollow structures were obtained by chemical vapor deposition using the water-soluble KI as the catalyst and the acetylene (C2H2) gas as the carbon precursor. The experimental results showed that the perfect carbon nanofibers can be prepared by using KI as the catalyst through controlling the factors such as temperature.
Keywords: foundational discipline in materials science; water-soluble catalysts; carbon nanofibers; nano-structure; KI
 
Title: Thermodynamic analysis on ageing process of Mg-Zn alloys
Authors: LI Xiumei, LI Changrong, DU Zhenmin, GUO Cuiping
PP: 2364～2372
Abstract: This paper is studied the Mg-Zn binary system. Firstly, the Gibbs free energy description of the Mg-based solid solution was typically re-optimized with the help of the Thermo-Calc software package. The obtained thermodynamic parameters could well represent the thermodynamic characteristics of the existence of the metastable miscibility gaps and the atomic clustering GP zones in the Mg-based solid solutions. Secondly, to guarantee the age hardening effect, considering both miscibility gaps and Spinodal decomposition curves, the required alloy composition range and the related ageing temperature were obtained, and the atomic clustering compositions of GP zones were predicted. Finally, with consideration of both the interfacial energies and the driving force analysis, the precipitation sequence during ageing process was obtained as the following: Supersaturated solid solution α→GP→β″1(MgZn2)→β″2(MgZn2)→β′(Mg2Zn3)→β(MgZn). The theoretical analysis was well consistent with the reported experimental results.
Keywords: foundational discipline in materials science; Mg-Zn alloy; ageing process; precipitation decomposition; thermodynamic analysis
 
Title: Study on the structure and properties of the AZ31B aluminium alloy diffusion joint
Authors: LIU Fenjun, DU Zhengliang, CHEN Shaoping, MENG Qingsen
PP: 2358～2363
Abstract: The diffusion-dissolution structure was formed in the interface of AZ31B/Al diffusion joint. The microstructure, phase composition and properties of the diffusion-dissolution layer were analyzed by means of metalloscope, scanning electron microscope (SEM), X-ray diffraction (XRD), microhardness tester and so on. It was found that the diffusion-dissolution layer with different width and zigzag combined with substrate was formed in the interface of AZ31B/Al.The diffusion-dissolution layer was composed by the solid solution and eutectic phases. Its average microhardness was improved about 98% and its self-corrosion current was improved about 77%.
Keywords: material synthesizing and processing；AZ31B magnesium alloy; aluminium; diffusion welding; diffusion dissolution layer; erosion resistance
 
Title: Dielectric properties of Ba0.50Sr0.50TiO3-MgTiO3 composite thin films prepared by sol-gel method
Authors: GAO Lina, ZHAI Jiwei, YAO Xi
PP: 2353～2357
Abstract: In this work, MgTiO3 (MT) with low dielectric constant and low loss was used as compound phase and Ba0.50Sr0.50TiO3 as prrincipl phase for the fabrication of the Ba0.50Sr0.50TiO3-MgTiO3（BST-MT）composite thin films by sol-gel method. The dielectric properties of the composite thin films were characterized by measuring the dielectric constant and dielectric loss as functions of applied electric field and frequency. As a result, both MT and BST remained as two distinct individual entities in the composite thin films and a considerable reduction in the dielectric loss had been observed. The composite thin films with low dielectric constant and low dielectric loss could be attractive materials for tunable microwave device.
Keywords: materials physics and chemistry; composite thin films; sol-gel; tunability; dielectric properties