15 August 2013, Volume 44 Issue 15
    

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    研究 开发
  • Investigation on Mixed Potential NO2 Sensor Based on Nano-structured CuO Sensing Electrode
    Ling Wangyunfei wang;
    . 2013, 44(15): 1-0.
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    A mixed potential NO2 sensor was fabricated by using yttria-stabilized zirconia (YSZ) electrolyte and nano-structured CuO sensing electrode (SE) prepared by sputtering method. The composition and microstructure of the CuO sensing electrode were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The impact of sputtering time on the microstructure of CuO and the sensitivity of the sensor was studied. The results showed that with the sputtering time increasing, the CuO particle size increased. The sensors showed good sensitivity to 25~400mL/m3 NO2 and the response signals of the sensors were linearly dependent on the logarithm of NO2 concentrations in the temperature range of 600~700℃. The sensitivity of the 60min-Cu sensor was up to 41.47mV/decade at 650℃. The 90% response and recovery time of the sensor were 160s and 260s, respectively operating at 650℃, 400mL/m3 NO2. The response was slightly affected by changing CO2 concentrations in the range of 0~10vol %. The sensor showed good response, recovery, reproducibility and stability.
  • Influence of hydrogen annealing temperature on the optical and electrical properties of ZnO thin films prepared by magnetron sputtering
    Zhou Ming
    . 2013, 44(15): 2-0.
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    In this paper, ZnO thin films were prepared on glass slide substrates using DC magnetron sputtering method at room temperature . The samples were annealed in the ambient atmospheres of atmospheric hydrogen gas under different temperature. The results indicated that the sample obtained under 500 ℃ has optimum optical and electrical performance, its whole average transmittance in the wavelength range of 360nm~960nm was 76.35%, and the sheet resistance was 6.3 kΩ/□.
  • In-plane crushing response and energy absorption characteristics of metal honeycombs
    . 2013, 44(15): 3-0.
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    The dynamic crushing response and energy absorption characteristics of triangular honeycombs under in-plane impact loading are numerically investigated by means of explicit dynamic finite element method in this paper. The effects of relative density, impact velocity and impact direction on the deformation modes, plateau stresses and specific energy absorption abilities of honeycombs are discussed in detail. Research results show that except for the cell micro-structural parameters(e.g. edge length, edge thickness, expanding angles, etc.), the dynamic response characteristics of triangular honeycombs also depends on impact velocities and impact directions. Under the conditions that the relative density and impact velocity are all the same, the plateau stresses and energy absorption abilities of metal honeycombs in the Y direction are both higher than ones in the X direction.With the increase of impact velocity, the inertia effect plays an important role in the dynamic crushing of metal honeycombs. And impact direction has great influence on plateau stresses and energy absorption abilities. These results will provide new guidance in the multi-objective optimization design of impact dynamic properties of cellular materials.
  • Synthesis and antibacterial activity of O-hexanoyl quaternary ammonium chitosan
    ;;;
    . 2013, 44(15): 4-0.
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    O-methyl free N,N,N-trimethyl chitosan (TMC) was synthesized through two steps, then TMC and Hexanoyl chloride were used to prepare N,N,N-trimethyl-O-hexanoyl -chitosan(TMHC).The products were characterized by 1H NMR、FTIR and EA . The results of antimicrobial test indicated that the antibacterial activity of TMHC was stronger than TMC by acylation modification, and increased with the degree of substitution increased. TMHC showed stronger antibacterial activity against S. aureus than against E. coli. In addition, the same concentration (50 mmol/L) of divalent cations reduced the antibacterial activity of TMHC in the following order:Ba2+ > Ca2+ > Mg2+. And the antibacterial activity inhibition of TMHC at the same metal ion (Mg2+) condition reduced with the ion concentration increased.
  • Wetting and Interfacial Reaction of the Metal Supports for Oxygen-Permeable Membranes by Ag-Cu Brazing Filler
    Yu-Wen ZHANG ;;
    . 2013, 44(15): 5-0.
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    The effect of Cu content on the wettability and interfacial reaction of metal supports for oxygen-permeable membranes brazed with Ag-Cu filler was investigated. The microstructure of the interface was observed by SEM and the constituent phases were analyzed by EDS. The results show that pure Ag exhibits poor wettability on the 310S stainless steel supports; the contact angles decrease rapidly when the Cu content increases from 0 to 2% and then the contact angles decrease slowly with the increasing of Cu content. The wettability of Ag-Cu/310S system in air was improved by reaction between CuO in brazes and the surface layer of 310S to form a new Cu-Cr-Fe-O oxide and to destroy the passive film from the 310S surface.
    • 工艺 技术
  • Preparation and properties of magnetic Ag+/organic zeolite 5A composite antibacterial agent
    qiong ZHANG
    . 2013, 44(15): 6-0.
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    Abstract 　　CoFe2O4 magnetic fluid and zeolite 5A which are respectively prepared by reflux method and hydrothermal synthesis are combined to produce a magnetic zeolite 5A with the different weight ratio of CoFe2O4 are used to produce the magnetic silver type zeolite 5A by the ion exchange method.At last,the magnetic silver type zeolite 5A combined with the organic antibacterial agent is to magnetic Ag+/organic zeolite 5A composite antibacterial agent which is characterized by the morphology,the size,the magnetic properties,the antibacterial properties,the magnetic separation recovery performance after dealing with the wastewater contained bacteria in the test.The results show that the granularity of CoFe2O4 magnetic particles with stable property and super paramagnetism is 12.7nm;The majority of zeolite 5A whose surface is attached by nanometer CoFe2O4 have cube crystal completely. the staturation magnetization(Ms),remanence magnetization(Mr) and coercive force(Hci) of magnetic zeolite 5A with CoFe2O4 contents of 25% are 17.842(A·m2·kg-1),4.8257(A·m2·kg-1),427.73G,respectively. Antibacterial ratio of composite antibacterial agent to staphylococcus aureus and Escherichia coli are 99.02% and 99.17% when the adsoption content of Ag+ reaches 271.71mg/g and the addition of organic antibacterial agent reaches 3.5%,respectively;The antibacterial agent can be recoveried from suspension with magnetic separation techonogy after the magnetic zeolite 5A is used to deal with wastewater contained bacteria. As the content of CoFe2O4 is 25%, The magnetic separation recovery rates of magnetic zeolite 5A composite antibacterial agent is 96.14%.
    • 研究 开发
  • Effects of P on Preferential Prientation and Grain Size of Nd-Fe-B Nanocomposite Magnets
    . 2013, 44(15): 9-0.
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    In this study,preferential orientation and grain size were studied for Nd9.5Fe84B6.5-xPx (x=0, 0.1, 0.2,0.3,0.4 ) ribbons prepared via melt-spinning. P addition is found to be effective for the orientation of c-axis of Nd2Fe14B grains perpendicular to the ribbon plane. Both the free and wheel side of the ribbons could obtain strong c-axis crystal texture of Nd2Fe14B phase at low P content,but the texture weakened gradually with the increase of P content. Moreover,the intensity of the texture is stronger in the free side of the ribbon than that of the wheel side. The Nd2Fe14B grain size changes with P content in both side of ribbons and is smaller when P content is 0.1at% , and lead to coarser when the increase of P content .In addition ,the Nd2Fe14B grain size in the free side is larger than that of the wheel side.
  • Study on reinforcing and Toughening of graphene oxide to cement-based composites
    . 2013, 44(15): 10-0.
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    Nano-graphene oxide (GO) aqueous was prepared by oxidizing graphite according to Jummers method and ultrasonic dispersion. The effects of GO on the concrete properties doped with polycarbonate superplasticizer (PCs) were investigated by measuring the fluidity, viscosity and setting time of cement pastes, pore structure of hardened cement paste, folding strength and compression strength of mortar in the presence of PCs. The results indicated that nano-graphene oxide could make lightly decrease of fluidity and setting time and make hardened cement paste become dense and decrease larger pore number and remarkable increase folding and compression strength of mortar. The results of XRD and SEM testing showed that the GO could lead and promote cement hydration to produce more crystal products with regular shape, which also hints GO could exhibit template role for cement hydration. Therefore, research the effect of nano-graphene oxide on cement composite microstructure is importance to reinforcement and toughing of concrete and prolongs concrete life.
  • Effect of horizontal magnetic field on the microstructure of directionally solidified Cu-10%Ag alloy
    Yan LIU
    . 2013, 44(15): 11-0.
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    Abstract: The directional solidification experiment of Cu-10%Ag alloy was carried out under horizontal static magnetic field, the macrostructure, microstructure and hardness of Cu-10%Ag were investigated. Without magnetic field condition, it was found that the grains are coarser and longer, the diameter arms and spacing of Cu dendrites are coarser too, moreover, the orientation of the dendrites is uniform, meanwhile, the size of the eutectic is larger; With 1T horizontal magnetic field, the grains increase and become refinement, the diameter and spacing of Cu dendrites become thinner, and the orientation of the dendrites is random, moreover, the size of the eutectic is smaller and the hardness increased too. As comparing the difference of the proeutectic Cu dendrites and eutectic with and without horizontal magnetic field, the mechanism was discussed in this paper.
  • Synthesis and antimicrobial properties of flowerlike copper nanomaterials
    ;;;Lei Sun ;
    . 2013, 44(15): 12-0.
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    The flower-like copper nanomaterials modified by polyvinylpyrrolidone (PVP) and carboxymethyl chitosan (NOCC) were successfully synthesized by chemical reduction method in aqueous solution, respectively. The morphologies and structures of the copper/polymer nanocomposites were characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM) and x-ray powder diffraction (XRD). The results show that the as-synthesized surface modified Cu nanoparticles exhibit a face centered cubic crystalline structure. A flowerlike self-assembled nanostructure was observed by SEM with PVP and NOCC as soft template. The minimal inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus) and Pseudomonas aeruginosa (P. aeruginosa) were evaluated by the method of inhibition zones and broth dilution. Biological experiments show that the as-synthesized Cu nanomaterials exhibit excellent antibacterial properties and have a potential application prospect.
  • Preparation of ordered mesoporous tungsten carbide/carbon composites by nanocasting method and its electrocatalysis
    ;;
    . 2013, 44(15): 13-0.
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    Highly ordered mesoporous tungsten carbide/carbon composites (WC/C) have been successfully synthesized by using phenol-formaldehyde (PF) resin and ammonium tungsten oxide hydrate (AMT) as the precursors, mesoporous silica as hard templates. In the synthesis procedure, first, introduced the precursors via a one-step nanocasting followed by high-temperature carbothermal treatment under a flow of N2/H2 mixture for a certain time. The mesoporous WC/C with two-dimensional (2-D) hexagonal or 3-D bicontinuous cubic arrays can be easily replicated from mesoporous silica SBA-15 and KIT-6 templates, respectively. XRD, TEM, EDX, TGA, Cyclic voltammograms (CV) and N2 sorption techniques were employed to characterize the mesoporous WC/C composites. The results show that the resultant materials have an ordered mesostructure (P6mm, Ia3d), high surface areas (~500 m2/g) and relatively large mesopores (~4nm). Pt supported on ordered TC/C-KIT-6-3 demonstrates larger apparent electrocatalytic current, higher electroactivity than Pt-TC/C-SBA-15-b catalyst.
  • Effect of Reaction Temperature and Time on Properties of Esterified Starch Prepared by Dry Method
    ;ZUO Yingfeng; ;
    . 2013, 44(15): 14-0.
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    maleic anhydride esterified starch was prepared by dry method, and then the properties of esterification starch were studied by reaction temperature and time. Infrared spectrum (FTIR) was used to prove that maleic anhydride was reacted with starch successful. Using chemical titration method, X ray diffraction (XRD), differential scanning calorimetry (DSC) and thermo gravimetric analysis (TGA) analysis the substitution degree, crystal structure, gelatinization temperature and thermal stability of esterification starch. The results show that substitution degree was increase with the increase of the reaction temperature and time gradually. Esterification reaction damage starch crystal structure in a certain extent, the crystallinity decreased gradually along with the increase of reaction temperature and reaction time. Gelatinization temperature and thermal stability had closely related with the crystallinity of esterified starch. Gelatinization temperature and the thermal stability were decreased along with crystallinity increases gradually.
  • Separation of Single-walled Carbon Nanotubes by using an anthryl and Benenediazonium compound
    ;;
    . 2013, 44(15): 15-0.
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    Single-Walled Carbon Nanotubes (SWNTs) have received much attention because of their excellent physics and electrical properties, but nowadays SWNTs are typically grown as mixtures of metallic-SWNTs (met-SWNTs) and semiconducting-SWNTs (sem-SWNTs), which limited their widespread application. In this paper, the compound fluoroborate diazonium salt of 1-(9-anthryl)-3-(4-aminopheny1)-2-propen-1-tone (donated A for convenience) had been designed and successfully synthesized for the first time. It has two functional groups: polycyclic aromatic hydrocarbon and benediazonium. This compound A was used to separate SWNTs in a simple sonication-centrifugation procedure. Resonant Raman spectra with 532, 633, 785nm lasers both showed highly effective enrichment of met-SWNTs in the precipitation and enrichment of sem-SWNTs in supernatant solutions.
  • Effects of solution composition on morphology of macropore arrays etched by electrochemical etching on high ρ n-Si
    ;;;Chang-Yong Zhan ;;;
    . 2013, 44(15): 16-0.
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    Silicon macropore arrays are prepared on high ρ silicon wafer by electrochemical etching method and the surface and cross-section of the arrays are presented. The effect of etching solution on morphology of macropore arrays is studied in this paper. The results show that the morphologies of the Silicon macropore arrays are greatly affected by the composition of etching solution. Under the same other conditions, the wall of inner hole becomes smooth and flat with decreasing ethanol. And it is found that the size and depth of the macropores are changed with changing HF concentration. The related mechanism is discussed.
  • Effect of (V, Ti) (C, N) composite powders on the properties of WC-8%Co cemented carbide
    ;; Jun ZHU;;
    . 2013, 44(15): 17-0.
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    Three kinds of ultrafine (V, xTi)(C,N) solid-solution powders were synthesized by CRN method, where x is 5, 10, 15 wt.%, respectively. The effects of (V, Ti)(C,N) solid-solution powders on microstructure and mechanical properties of WC-8%Co sintered samples were researched. The experimental results showed that (V, Ti)(C,N) ultrafine powders can obviously improve the mechanical properties of WC-8%Co cemented carbides compared with V(C,N) or V(C,N) /Ti(C,N) grain growth inhibitors.WC-8%Co cemented carbides with 0.5wt.% (V,5Ti)(C,N) have optimal mechanical properties of bending strength of 3490MPa and hardness of 1804 HV30. The grain growth is inhibited at about 0.5~0.6μm in size.
  • Research on adsorption characteristics of magnetic polyphosphazene nanotubes to methylene blue
    Xiao-Yan ZHANG
    . 2013, 44(15): 18-0.
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    Magnetic polyphosphazene nanotubes with magnetic phases embedded in the walls were synthesized via an in situ template approach at room temperature. The magnetic phosphazene nanotubes in application of adsorbing methylene blue were studied. The effects such as adsorption time, adsorption temperature, the initial concentration of methylene blue and the amount of magnetic phosphazene nanotubes on the adsorption property were discussed. The results show that the magnetic phosphazene nanotubes with magnetism content of 11.5% and magnetization saturation value of 2.68 emu/g exhibit strong magnetic responsivity and can be quickly concentrated by magnet after dispersed in the water. Moreover, the adsorption behaviour basically follows Langmuir’s model. The adsorption ratios increase with the time and the amount of magnetic phosphazene nanotubes, and decrease with the initial concentration of methylene blue. The adsorption capacity and ratio increase with temperature and the adsorption behaviour is almost finished at 60℃.
  • Synthesis and Characterization of Al/MoO3 and Al/Fe2O3 nano-energetic films
    . 2013, 44(15): 19-0.
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    The Al/MoO3 and Al/Fe2O3 nano-energetic films were produced by magnetron sputtering technology. The morphology, size, phase structure, XPS spectrum and thermodynamics of nano-energetic films were characterized by SEM, AFM， XRD, XPS and Differential Scanning Calorimetry(DSC). The results show that the surfaces of the as-obtained films are neat and the layered structures are very clear. Most of MoO3 is restored to Mo2O5 and MoO2 in the Al/MoO3 films. Partly of Fe2O3 is reduced to FeO in the Al/Fe2O3 mulitlayer films. A small amount of Al is oxidized to amorphous Al2O3 in the both of films. The temperature of initial exothermic peaks and the activation energy are so low that the reactivity is pretty high and the values of heat release are large, which are -3198 J/g and -1680 J/g, respectively.
  • Experimental Investigation on Relationship between Additives and Thermal Conductivity of BN/EG anofluids
    ;;;;
    . 2013, 44(15): 20-0.
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    Boron nitride/ethylene alcohol (BN/EG) nanofluids and Boron nitride nanotubes/ethylene alcohol (BNNTs/EG) nanofluids were synthesized by two-step method. Thermal conductivity of them were measured by transient hot-wire method. The effect of nanoparticles volume fraction, size, shape and morphology of aggregation on thermal conductivity enhancement of BN/EG nanofluids was investigated. The experimental results indicated that the thermal conductivity enhancement of the BN/EG nanofluids increased with the increment of nanoparticles volume fraction, size and aspect ratio. Chain-like loose aggregation of BN nanoparticles is more favourable for thermal conductivity enhancementt of BN/EG nanofluids compared to Cloud-like compact aggregation of BN nanoparticles.
  • Effect of microalloying on phase transformation and mechanical properties of the Ni41Ti44Cu7Zr8 alloys
    ;
    . 2013, 44(15): 21-0.
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    Microalloying affected the yielding stress of the martensite in the Ni41Ti44Cu7Zr8 alloy. Addition of element with proper atomic radii and mixing enthalpy with Ti atom simultaneous improved the yielding stress of the martensite by solution strengthening. And addition of Fe lowered the phase transformation temperature of the Ni41Ti44Cu7Zr8 alloy drastically. By addition of 1at% Fe, the transformation temperatures reduced about 48℃, resulting a superelastic alloy at room temperature. While, with 3at% Fe addition, the transformation temperatures reduced above 88℃, and the resulting alloy didn’t shown any shape memory effect at temperature.
  • Effect of magnetic separation fly ash on the compression sensitivity of CFRC
    Xing-Wen Jia ;;
    . 2013, 44(15): 22-0.
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    Improving the compression sensitivity of carbon fiber reinforced cement (CFRC) is help to promote its capacity in perceiving stress and strain. In this paper, the effect of magnetic separation fly ash (MSFA) on compression sensitivity of CFRC was investigated by two electrode methods. Factors affecting the compression sensitivity of CFRC, such as MSFA content, iron oxide content, were analyzed. Results showed that the substitution amount of MSFA instead of cement is up to 20% to 30% will promote the compression sensitivity of CFRC significantly when the quality dosage of carbon fiber is not greater than 0.8%. MSFA is not conducive to improve the compression sensitivity of CFRC when the quality dosage of carbon fiber is 1.2%. MSFA has prominent effect on the compression sensitivity of CFRC when the maximum length of carbon fiber is 3mm and 5mm. When the content of carbon fiber is low, the application of appropriate amount of MSFA in CFRC not only provides excellent compression sensitivity, but also reduces the cost of CFRC.
  • Experimental research and numerical simulation on melting and solidification of metal foam composite phase change material
    Qiang Sheng
    . 2013, 44(15): 23-0.
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    Due to the adsorption performance of the high porosity metal foam structure, metal foam composite phase change energy storage material was prepared by using barium hydroxide octahydrate (Ba(OH)2?8H2O) as phase change material (PCM) and copper foams as supporting matrix. Phase change temperature and latent heat of Ba(OH)2?8H2O were measured with differential scanning calorimetry (DSC). An experimental setup was built to study the heat transfer performances of phase change thermal storage units (TSUs) with and without copper foams. The enthalpy-porosity model was adopted to simulate solid-liquid phase change process. The experimental and numerical results indicate that the thermal conductivity is improved and the phase change time is shortened. The reliability of mathematical model is verified that the numerical results match well with the experimental results. The conclusion provides guidelines for phase change TSU application.
    • 工艺 技术
  • Template-free synthesis of CdS microspheres by hydrothermal process
    Zhen-Feng ZHU
    . 2013, 44(15): 24-0.
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    Abstract: The uniform CdS microspheres were synthesized by template-free hydrothermal method. The morphology and structure of CdS microspheres were characterized by XRD analysis and SEM. The results indicate that the synthesis by hydrothermal method to avoid the S2- iro oxidation, the CdS microspheres of obvious quantum size effect of smooth surface were synthesized on the appropriate heat preservation temperature and time.
  • The preliminary research on EVA sole foaming materials with wet grafted starch
    Yu -Ying ZHENG
    . 2013, 44(15): 25-0.
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    The modified starch was prepared through the soluble starch wet graft vinyl acetate and the environmental friendly EVA sole foaming materials were obtained with the modified starch. The effect and structure of the modified starch was analyzed by FT-IR, grafting ratio and grafting efficiency, while the mechanical properties and microscopic morphology of the modified starch/EVA sole foaming materials were also investigated. According to the results, the FT-IR spectrum of the modified starch showed a adsorption peak at 1746 cm-1, which was assigned to the stretching vibration of the carbonyl group and indicated that the monomer of vinyl acetate might graft onto the bone of the starch. The best initiator concentration was 6 mmol/L and the optimum reaction temperature was 70 ℃. The SEM pictures demonstrated that the modified starch and EVA had good compatibility. The proportion of wet grafted starch/EVA sole foaming materials were lower than traditional EVA sole foaming materials, when the content of the grafted starch was 40phr, the proportion of the composite foaming materials reached the minimum, which was 0.085 g/cm3.
  • Investigation on C/N Control of Ti(C,N) Powder Prepared by Ilmenite
    Min CHEN
    . 2013, 44(15): 26-0.
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    Abstract: Ti(C,N) micron powder was synthesized using ilmenite and graphite as raw materials via carbothermic reduction under nitrogen atmosphere. The influence of carbon contents, reaction temperature, holding time and nitrogen partial pressure on C/N control of TiC1-xNx powder was mainly investigated by X-ray diffraction. The C/N control critical factors and quantitative relationship were obtained.
  • Preparation of Cu-Cr-O Catalyst and Its Application to Carbon Nanotubes Synthesis
    Judy JIAN
    . 2013, 44(15): 27-0.
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    Cu-Cr-O nano-composite powder catalyst was prepared via an alcohol-water co-precipitation process and was applied to the synthesis of carbon nanotubes. Techniques of thermo-gravimetric/ Differential Scanning Calorimeter (TG-DSC), X-ray diffraction (XRD) as well as transmission electron microscope (TEM) and scanning electron microscopy (SEM) had been employed to characterize the thermal decomposition procedure, crystal phase, micro structural morphologies of the as-synthesized materials, respectively. The results show that there are differences among materials calcinated at different temperature, among which well-crystallized Cu-Cr-O nano-composite catalyst can be produced by calcinated the precursor at 600℃.The quality and morphology of carbon nanotubes synthesized by different Cu-Cr-O composites calcinated at various temperatures have great differences, and CNTs with high purity and smooth surface can be obtained when the catalyst is calcinated at 600℃.
    • 研究 开发
  • Regulation on the thickness of Aligned Carbon Nanotube arrays
    ;; ;TANG YONGJIAN
    . 2013, 44(15): 28-0.
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    Abstract: Aligned Carbon Nanotube arrays (ACNTs) have been prepared by chemical vapor deposition(CVD). The growth thickness of ACNTs has been investigated systematically. The morphology and structure of samples are characterized by Scanning Electron Microsco py(SEM) and Raman Spectroscopy. The results indicate that at the same growth time and for a certain rang of concentration of catalyst, the thickness of ACNTs adds with the concentration of catalyst improving. The thickness of ACNTs decreases with the flowing rate of carrier gas increasing, and the trend of the decline of ACNTs is nearly linear. The thickness of ACNTs increases with the growth time prolonging and the growth rate increases to 24μm/min in the initial 60 minutes and slows down after 60 minutes.
  • Preparation and fluorescent performances of spherical SrMoO4:Eu3+ phosphor by spray pyrolysis
    . 2013, 44(15): 29-0.
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    Abstract: Spherical SrMoO4:Eu3+ phosphor was prepared by spray pyrolysis. The influences of temperature on phase composition, microscopic morphology and fluorescent performances of the SrMoO4: Eu3+ phosphor were investigated. The results indicated that pure SrMoO4 phase could be obtained at different temperatures. Part of SrMoO4 particles prepared at 300℃ by spray pyrolysis had hollow spherical structure, and SrMoO4 particles with solid spherical structure were prepared above 300℃ by spray pyrolysis. The emission intensity of the SrMoO4: Eu3+ phosphor prepared at 500℃ was the strongest.
  • The effects of additives on preparation of CoFe2O4
    . 2013, 44(15): 30-0.
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    Nano-crystal cobalt ferrite was synthesized from spent lithium ion batteries through a hydrothermal process. The effects of additives on the magnetic properties of Co-ferrite were studied. Their characterizations were investigated by X-ray diffraction (XRD), Infrared spectrophotometer (IR), thermogravimetry (TG) and vibrating Sample Magnetometer (VSM). The results show that cobalt ferrite is conducive to the generation and the improvement of magnetic properties by adding appropriate amount of glacial acetic acid, but excessive addition of glacial acetic acid will make the final product contains acetic acid roots, while also reducing the magnetic properties of cobalt ferrite. In the precipitation process by adding citric acid additives are not so conducive to the formation of cobalt ferrite.
  • Study on the Mechanisms of Influence of Annealing Temperature on TA2/NiCr Explosive Compound Bar
    Xie-Bin Zhu
    . 2013, 44(15): 32-0.
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    The paper studied the effect of different heat treatment temperatures (510℃，550℃， 590℃，630℃，670℃)×30 min on deformation microstructure, hardness, diffusion component of Ti/NiCr explosive cladding bar. The results show that as the temperature increases, the recovery, recrystallization and grain growth occur, the hardness gradually reduces. Under the annealing of 630℃, the deformation microstructure of cladding transformes into fine equiaxial grains and hardness is low relatively. The micro segregation and crack of the melting zone is eliminated basically, component stable, microstructure uniform, and the size of grain increases obviously. The effect of grains refining is weakened, the plasticity and toughness will be decline. Before the annealing of 630℃, the cladding is constituted of a large number deformation microstructure and hardness is high relatively. Therefor the annealing temperature of 630℃ is suitable for the explosive compound bar.
  • Synthesis and properties of different corona structure Fe3O4 solvent-free nanofluids
    ;
    . 2013, 44(15): 33-0.
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    Fe3O4 solvent-free nanofluids were prepared with N-Trimethoxysilylpropyl-N,N,N-trim- ethylammonium chloride as corona and anion C9H19-C6H4-(OCH2CH2)20O(CH2)3SO3- as canopy. Rheometer properties of different corona structure nanofluids were compared. The product was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrum (FTIR), thermogravimetric analysis (TGA) and rheometer. As a result, Fe3O4 nanoparticles possessed good dispersion, and the content of Fe3O4 nanoparticals in the nanofluid proved to be about 10.42%. The loss shear modulus G〞of the product was obviously higher than the storage shear modulus G′, this showed that the product which could flow at room temperature had obvious rheological behavior. For the solvent–free nanofluids, the long chain corona has the internal plasticization, which can decrease the loss modulus of system, while the short chain of corona will result in the high viscosity of nanofluids. Long alkyl chains of modifiers lead to lower viscosity and better flowability of nanofluids.
  • Aramid paper's structure and performance and their effect on the mechanical properties of Aramid paper honeycomb
    ; ;;;;
    . 2013, 44(15): 34-0.
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    ramid paper is the raw material for the manufacture of aramid paper honeycomb. The structure and performance of the paper have an important impact on the mechanical properties of the honeycomb. The meta-aramid paper has a tight structure and its surface exhibits a form of membrane, however the structure of Para-aramid paper is relatively looser, thus it's easy for resin to impregnate into the paper. The product of Young’s Modulus and thickness E_s t of the cell wall after resin impregnation is the key performance that effects the modulus of aramid paper honeycomb. Corresponding to the honeycomb of the same specification, Because the E_s t value of Para-aramid paper is much higher than that of meta-aramid paper, the compression and shear modulus of the Para-aramid paper honeycomb is also higher than meta-aramid paper honeycomb for same types honeycomb. As well, the compression and shear strength of Para-aramid paper honeycomb are higher than the meta-aramid paper honeycomb.
  • Isothermal Crystallization Behavior of GO/PA6 Composite
    . 2013, 44(15): 35-0.
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    The graphene oxide (GO) / nylon6 (PA6) composite was prepared by solution blending method, and the isothermal crystallization behavior of the system was studied by means of differential scaning calorimetry (DSC) and polarizing optical microscopy (POM). The results showed the Avrami equation can describe successfully the isothermal crystallization behavior of nylon6 and GO/PA6 composite. The nanoparticles of GO dispersed in PA6 matrix could serve as effective nucleating agent, which make the crystallization rate of composite accelerated and the activation energy reduced. Meanwhile, the crystallization rate and the absolute crystallinity would decrease with the enhancement of isothermal crystallization temperature. Moreover, polarizing optical microscopy (POM) revealed that the spherulite size of PA6 was minimized by the addition of GO.
  • Design and emulation of combined-shaped electromagnetic stealthy cloak made of metamaterials
    Ye LIU; ;
    . 2013, 44(15): 36-0.
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    Based on the method of coordinate transformation, the distributions of the electromagnetic parameters in the elliptical and trapezoidal transformed spaces are derived. Aimed at combined target, the electromagnetic stealthy cloak made of metamaterials is designed. On the condition that TE wave of 400MHz enters normally into the domain, the stealthy characteristic of stealthy cloak is emulated. The result of emulation shows that few waves penetrate into the interior of the target model because of the stealthy cloak. Besides, the electromagnetic field outside the cloak has no obvious change. So the excellent stealthy characteristic of the cloak is verified. The entire phenomenons are in accordance with the predicted results in theory. Therefore, metamaterials designed by coordinate transformation, have the capacity of controlling the path of electromagnetic wave’s transmission and making little influence to the external electromagnetic field theoretically.
  • Numerical Simulation and Experimental Study of Shielding Effect of Landmine Shell Made with Composite Material to UWB Electromagnetic Pulse
    Xian-nan Luo
    . 2013, 44(15): 37-0.
    Abstract ( ) Download PDF ( ) Knowledge map Save
    A new kind of composite material was prepared by using stainless steel fibers to fill polyamide resin and columned shells were made with it. When electronical fuzes connected with electrical fire head were fit under the shell in the microwave anechoic chamber, experiments of damage effect of UWB electromagnetic pulse radiation with peak power of 1GW were conducted. The frequency band of pulse energy was mostly between 10MHz and 2GHz. When the distance between shell and antenna was more than 50cm, the fuze in the shell could work normally. Numerical calculation results showed that the shielding effect was more than 25dB, and the experiment results showed good agreement with them. When shells had a hole with a radius of less than 4.5 mm, both experiment and numerical calculation results showed that holes had minute influence on shielding effect. Shells made with composite material could promote the viability of landmines with electronical fuze in high power electromagnetic environment.
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