15 September 2012, Volume 43 Issue 17
    

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    研究与开发
  • Preparation of High Temperature Infrared Emissivity Energy-Saving Coatings and Its Application
    . 2012, 43(17): 1-0.
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    Through using SiO2, Fe2O3, Cr2O3 and MnO2 powders as raw materials, the high temperature infrared emissivity energy-saving coatings were prepared by combined solid-state and milling method. The physical and chemical properties and microstructures of the obtained coatings were characterized by X-ray diffraction (XRD), hemisphere-point test, infrared radiation meter and nano-particle size meter. And their thermal shock resistance was also investigated by wind quenching-cracks determination method. The results show that the prepared SiO2-Fe2O3-Cr2O3-MnO2 coating systems exhibit a infrared emissivity of 0.93 in the band of 1-22 μm and good thermal shock resistance, and that their operating temperature can be up to 1400 ℃. Besides, when the prepared coatings were applied in gas shuttle drying kiln, the energy consumption of the kiln decreased by 15%. After one year of use, their infrared emissivity remains up to o.90, which indicates that the coatings have excellent anti-aging performance.
  • Microstructure and mechanical properties of super-cooled process for transient liquid phase diffusion bonding zone of Mg/Zn interlayer /Al
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    . 2012, 43(17): 2-0.
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    The AZ31 Mg alloy/Zn interlayer/5083 Al alloy was joined by super-cooled process for transient liquid phase diffusion bonding. The joints were investigated for microstructural features, phase structure, microhardness, mechanical properties by scanning electron microscopy (SEM) 、Energy Dispersive Spectrometer(EDS) 、microhardness tester and X-ray diffractometer. The experiment results show that Mg/Al could be bonded by Super-cooled process for transient liquid phase (TLP) bonding technology using Zn as interlayer and the highest tensile strength of the joints is 38.5MPa, As the diffusion holding time at low temperature was prolonged, found that the diffusion layer thickness and tensile strength increase, and the tensile fracture is Brittle Fracture. There are the intermetallic compounds MgZn2 and little Mg17Al12, and the highest hardness is 170 in the joint zone.
  • Hierarchical Multi-scale Calculation of Electromagnetic Shielding Effectiveness for Fiber Composites
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    . 2012, 43(17): 3-0.
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    In order to establish the correlation of electromagnetic response between macro-scale and meso-scale of composites, the hierarchical multi-scale calculation method is applied to the calculation of electromagnetic shielding effectiveness of fiber composites. In order to describe the relationship between macro-scale and meso-scale of composites accurately, representative volume elements (RVE) of the composites meso-structure is determined by the measure criterion of electromagnetic shielding effectiveness. The equivalent electromagnetic parameters are calculated by the constitutive equation of electromagnetic field medium. The electromagnetic shielding effectiveness of fiber composites macro component is calculated by hierarchical multi-scale calculation method. The results showed that: the RVE of composites becomes smaller with the increasing of working frequency, the electromagnetic shielding effectiveness of fiber composite structures is above 38dB in the range of working frequency from 2GHz to 18GHz, and the electromagnetic shielding effectiveness decrease with increasing of working frequency. The research method is suitable to solve electromagnetic shielding effectiveness of composites macro component of arbitrary shape which has uniform dispersion and regular distribution of meso-structure phase.
  • The Study Of Oil Absorption Of Natural Biomass Materials
    . 2012, 43(17): 4-0.
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    This research investigates the use of four kinds of natural biomass materials, namely wheat straw, corn stalks, sawdust and the dregs. The influence factors on oil-adsorbing properties were studied, such as particle size, adsorption time and oil types. The paper also studied the water absorption of the four kinds of materials in order to investigate the selectivity of water and oil. In addition, oil retain capacity was evaluated too. On the crude oil adsorption test ,sawdust and wheat straw have good oil absorption performance within the size range of 0.25 ~ 0.83 mm, and oil sorption capacities are approximately 5.79 g oil / g sorbent and 6.02 g oil / g sorbent, followed by corn stalks, oil absorption of the absorbing material between 0.15 ~ 0.18 mm is 5.02 g/g, the dregs of oil absorption between 0.18 ~ 0.20 mm is only 2.37 g/g. Comparison of four kinds of materials on the adsorption properties of organic compounds toluene and vegetable oil, the adsorption effect of the crude oil is better than vegetable oil and toluene. The four kinds of materials all have a certain amount of oil retention capacity, the oil retention capacity of sawdust is highest and oil-water ratio is greater than 1. Besides, natural biomass materials are solid wastes, they can be directly used as fuel after oil absorption, to achieve the purpose of waste by waste. The results show that natural biomass materials show a high performance as a low cost and environmental friendly sorbents for the removal oil from water. Natural biomass materials will have better development and application prospects in the area of oily wastewater treatment.
  • Preparation of TiO2/chitosan nanocomposited coatings and its application in antibacterial coated paper
    . 2012, 43(17): 5-0.
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    TiO2/chitosan nanocomposited coatings was prepared by the combination of nanosized TiO2, chitosan biguanidine hydrochloride, SBR latex and other additives. The surface structure of TiO2/chitosan nanocomposited coating samples was characterized by SEM and FTIR techniques. A new method of antibacterial coated paper based on the TiO2/chitosan nanocomposited coatings was carried out, and the microstructure and antibacterial properties of coated paper was characterized. It was shown that there was a significant increase in antibacterial properties when the paper was coated by TiO2/chitosan nanocomposited coatings. It was especially illustrated that with the increase of chitosan biguanidine hydrochloride amount in paper coatings, the antibacterial properties of coated paper can be persistently improved. When the proportion of TiO2, chitosan in nanocomposited coatings was equal, the antibacterial efficiency of coated paper to escherichia coli and staphylococcus aureus could attain to 86.55% and 92.19%, respectively.
  • Synthesis and Optical properties of chelostic liquid crystalline polymers with thermal reversible colorific change
    Ji-Wei WANG
    . 2012, 43(17): 6-0.
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    Abstract: A series of side-chain liquid crystalline polymers (P1-P6) were synthesized with poly(methylhydrogeno)siloxane and two cholesteric liquid crystalline (LC) monomers 4-allyloxybenzoylcholeseterate (M1) and 4-{4-[(4-(allyloxyl)-benzoyl]-butyloxocarbonyl}- benzoatecholesteryl (M2). The mesomorphic properties were investigated by fourier transform infrared (FT-IR), proton nuclear magnetic resonance spectra (1H-NMR), differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), polarizing optical microscopy (POM), and X-ray diffraction (XRD) measurements. All the monomers and polymers showed cholesteric mesophase with very wide mesophase temperature ranges. Polymer films demonstrate the reversible change of reflective color, and blue shift was observed from low temperatures to high temperatures on the first heating and cooling, even second heating, the results indicate that the polymers show nice thermal and optic stability.
  • Diffusion ability of hydrogen in Mg-Ni alloy electrode with different compositions and microstrcutures
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    . 2012, 43(17): 7-0.
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    In this study, MgxNi（x=1、1.5、2, in atom percent）alloy powders with different microstructures were prepared by using mechanical ball milling method. The effect of Mg/Ni ratio on the microstructure evolution of the alloys during ball milling was investigated by X-ray diffraction (XRD) and scanning electronic microscope (SEM) observation. The cyclic voltammetry curves of the Mg-Ni alloy electrodes with the different compositions and microstructure were measured under the different potential scan rates, and the hydrogen diffusion coefficients in these electrodes were calculated. The results show that lowering Mg/Ni ratio can promote the glass forming ability of Mg-Ni alloys during ball milling, and the complete amorphous structure can be obtained after ball-milled for 120 h and 160h for MgNi and Mg1.5Ni alloys, respectively. Hydrogen exhibits high diffusion ability in the electrode made by the fine and disperse MgNi alloy powders in the complete amorphous strcuture. The hydrogen diffusion coefficient is 1.98 10-8 cm2 / s in it.
  • Preparation and Characterization of Polyimide Porous Microspheres Grafting Methoxypolyethylene Glycols Side Chain
    Jian-Jun LU;;
    . 2012, 43(17): 8-0.
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    A new graft monomer as new diamine is synthesized by 3, 5-diaminobenzoic acid (3, 5-DBA) and methoxypolyethylene glycols (MPEG) through esterification reaction in the presence of catalyst. The porous polyimide microspheres is prepared by graft monomer and 3, 5-DBA simultaneously with pyromellitic dianhydride（PMDA）in the non-aqueous emulsion polycondensation and then process traditional two steps imidization and the final thermal treatment. The optimal condition of esterification reaction was confirmed by experiments: n(acid)/n(alcohol) is 1.3, the content of catalyst and water carrying（to PMDA by weight）are 5% and 120% separately and reaction time is 6 h. As the concentration of graft monomer in the PI increasing, the size of porous PI microspheres is increasing from 9.5 to 15.9μm; the value of glass transition temperature（Tg）is decreasing from 210℃ to 178℃. Porous PI microspheres with obvious and uniform porous structure were obtained when the concentration of graft monomer is 40% and the specific surface area is 148cm3/g ；The porous size can be controlled by the pressure of the thermal treatment stage in the muffle furnace.
  • Thermal properties of Ti coated diamond/Al composites
    Jian-Hua Wu;;;;
    . 2012, 43(17): 9-0.
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    The Ti coated diamond was achieved by salt-bath plating, and then the Ti coated diamond/Al composites were fabricated by squeeze casting. The effect of Ti coating on the microstructure and thermal properties of composites were investigated. The results show that the thermal properties of composites were improved by the Ti coating on diamond particles to get the good interface bonding and decrease thermal boundary resistance between diamond and aluminum, including a reduced thermal expansion and a high thermal conductivity. Under plating condition 850 °C and 180 min, thermal conductivity of Ti-coated diamond/Al is 488 W/m/K, along with average coefficient of thermal expansion is 9×10-6 /K between 50 °C -300 °C.
  • Numerical Simulation on Size Effect of Thermal Conductivity of 2D SiO2 Nanowire
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    . 2012, 43(17): 10-0.
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    Nano insulations have excellent insulating performance and find wide application in hypersonic vehicle thermal protection technologies. In this study a two dimensional computational model based upon phonon radiative transfer equation for phonon transport in the solid of nano insulations is established. The discrete ordinate method is used to solve the transport equation numerically. The size effects in the longitudinal and transverse conductivity are numerically simulated for a 2D silica nanowire. Results show that obvious size effect in the conductivity exists in the 2D nanowire and the conductivity is mainly influenced by the wire diameter. For the nanowire with the diameter between 2nm~4nm considered, its thermal conductivity is 15% less than the bulk material. Results obtained in this study may be useful in recognizing the heat transfer mechanism in solids of nano insulations
  • Preparation and Development Properties of Photosensitive Microcapsule for the Novel Information Recording Material
    . 2012, 43(17): 11-0.
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    The photodevelopment microcapsule is synthesized with interfacial polymerization method, which is a new type of optical information recording function material. Photodevelopment microcapsule realizes the synchronization of optical information recording and reappearance by diffusion of acid produced by photochemical action for the first in china. The property of optical information recording and reappearance of photodeveloment microcapsule is studied according to the changing of imaging density. Results show that cationic photodevelopment microcapsule has highly-efficient development characteristic, and the imaging density quickly comes to the maximum with exposure time prolonging, which has relation to the concentration of cationic photoinitiator and dye precursor. Clear reverse reaction of coloration in cationic photodeveloment microcapsule has been detected. The fading effect is evident when the concentration of cationic photoinitiator is high. The temperature has clear effect on the process of fading.
  • Influence of Processing Time on Microstructure and Corrosion Resistance of Ce-Mn Conversion Coating on Magnesium Alloy
    . 2012, 43(17): 12-0.
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  • Effect of Addition of Zr on As-cast Microstructure of hypereutectic Al-Si alloy
    Lin Chen; ;
    . 2012, 43(17): 13-0.
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    Abstract: The effects of addition of Zr whose content was 1%, 3% and 5% on as-cast microstructure of Al-20Si aluminum alloy were investigated using optical microscope, scanning electron microscope, X-ray diffraction, etc. The results showed that the size of primary silicon particles became bigger gradually with the increasing of the content of Zr. After the addition of Zr, the AlSi4Zr5 was obtained, and Zr poisoned the nucleuses causing the grain size growth; at the same time, α-Al dendritic halos surrounding the primary silicon particles were developed fully, and reduced the inhibition effect of growth of the primary silicon.
  • Synthesis of Silica Nanoparticles Assisted by Amino Acids:Optimal Design
    ;Yuan Hong TANG
    . 2012, 43(17): 15-0.
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    In this paper, silica nanoparticles were prepared by amino acids assisted method, The synthesis parameters were designed and optimized by the Taguchi experimental design method. And the influences of the amount of TEOS, H2O, L-lysine, and reaction temperature on the particles size distribution of the silica nanoparticles were investigated. The results showed that the reaction temperature T is the main factor which affects the particles size of the silica nanoparticles. By the optimum conditions of the experiment, silica nanoparticles with an average particle size of 8.75 nm were prepared by the amino acids assisted method.
  • Design and Coupling of Carbon Nanotube Membrane Thermoelectric Generator
    Jiang-Lei LU
    . 2012, 43(17): 16-0.
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    In order to solve the power problems of miniature devices such as great volume, heavy weight and difficult integration, the novel membrane thermoelectric generator (TEG) was designed by utilizing the thermoelectric properties of carbon nanotube (CNT) membrane. It could directly convert the thermal gas flow to the electric energy. The physical model of the membrane TEG was constructed. The thermoelectric theory and governing equations were researched. The CNT membrane thermoelectric cell was simulated by the finite element method, and the change trend of output power and voltage were analyzed. The methods of reducing the internal resistance were put forward, which could provide the theoretical foundation for optimizing the experimental model. The highly conducting, transparent CNT membrane was synthesized by the floating-catalytic chemical vapor deposition. The thermoelectric properties were consistent to the simulation results. The CNT membrane had fine pliability, so the cylinder or truncated cone structure of membrane TEG could be constructed by connecting many cells in series. It was easily integrated with micro-optical electromechanical systems, and had wide applied prospect and practical value.
  • Preparation and stab resistance of Kevlar/Surlyn composites
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    . 2012, 43(17): 17-0.
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    Kevlar/Surlyn composites were fabricated by mould pressing. The effects of pressing temperature, pressure, time and resin content on properties of composites were studied. The results show that the optimum proceeding condition is pressing temperature 170℃，pressure 3MPa，holding time 30min. Resin content has important effect on stab resistant property of composite. The optimum resin content is 47wt.%.
  • Preparation of Ru doping TiO2 and TiO2/SiO2 and its properties of splitting water into hydrogen under visible light irradiation
    Shao-qin PENG;;yuexiang li
    . 2012, 43(17): 18-0.
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    A series of photocatalysts with visible light activity, Ru/TiO2 and Ru/TiO2/SiO2, were prepared by sol-gel method, and characterized by SEM, XPS, XRD, UV-Vis DRS and electrochemistry. It was found that the phase transfer and the grain growth of TiO2 were inhibited by doping Ru and Si. The absorption intensity to visible light and the separation of photo-generated electrons and holes of Ru doped TiO2 and TiO2/SiO2 was promoted so that the activity of hydrogen generation from water increased under visible light irradiation. When doping content of Ru was 0.014 wt% in TiO2 and 0.021wt% in TiO2/SiO2 respectively, the photocatalysts exhibited the highest photocatalytic activity under visible light irradiation. The activity of Ru/TiO2/SiO2 was 5 times as high as that of Ru/TiO2.
  • Influences of Glycerol Concentration on Properties of Natural Pure Cellulose Membrane Prepared by NMMO Technology
    Dong-Na Dong LI
    . 2012, 43(17): 19-0.
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    Abstract: Natural pure cellulose packaging films were prepared by means of the dissolution of cotton cellulose in NMMO and glycerol was used as plasticizer, the effects of different glycerol concentration on properties were studied,The results showed that elongation at break increase, but the tensile strength decrease with the increase of glycerol concentration, and both change significantly; when the content increased from 2% to 5%, the oil transmission, oxygen permeation flux, water vapor permeability, the light transmittance, the transverse and longitudinal direction hot shrinkage rate increased by 13.4%, 3.0%, 16.7%, 22.4%, 58.8%, 54.7% respectively. It’s clear that glycerol concentration had weak influence on oxygen permeation, but the mechanical properties, the oil permeability, the water vapor permeability, the transparency and hot shrinkage rate change significantly.
  • Research on the Adsorption and Release Behavior of Protein on Hollow Multilayer Hydroxylapatite Microspheres
    Fan-Rong AI ;
    . 2012, 43(17): 20-0.
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    Hollow hydroxyapatite microspheres, consisting of a hollow core and a multilayer porous shell, were prepared by converting Li2O-CaO-B2O3 glass microspheres in dilute phosphate solution. Lysozyme was used as the drug model of proteins, then the adsorption and in vitro drug release behaviors were studied. It was found that the adsorption mechanism is different with various concentration of lysozyme solution. When the concentration is lower than 0.8mg/mL, the adsorption is occurred on the surface of microspheres, the adsorption behavior is in accordance with the Langumiar adsorption mode. In vitro release showed lysozyme is released completely in 48h. When the concentration is higher than 0.8mg/mL, more adsorption of lysozyme is occurred on the inner shell of the microsphere, the adsorption behavior is in accordance with the Henry adsorption model. And the release of lysozyme from the hollow HA microspheres could be lasted an extended period (up to 800h). The present delivery system established could be used as the controlled drug release carrier for proteins, such as growth factor.
  • Synthesis and antibacterial activity of N- alkyl quaternary ammonium chitosan derivatives
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    . 2012, 43(17): 21-0.
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    A formic acid-formaldehyde methylation (Eschweiler-Clarke reaction) was used to synthesize N,N-dimethylated chitosan(DMC) at first, then DMC and bromoalkane was used to synthesize N-dodecyl-N,N-dimethyl chitosan(DODMC) and N-hexadecyl-N,N-dimethyl chitosan(HDMC) according to Hoffman alkylation. The obtained chitosan derivatives were characterized by FTIR、1H NMR、EA、TG methods, respectively. The derivatives showed good antibacterial activity, and they exhibited stronger antibacterial activity against S. aureus than against E. coli. The antibacterial activity of chitosan derivatives was increased as the length of alkyl increased. The antibacterial activity of chitosan derivatives was stronger under pH 5.5 than under pH 7.2; The results suggested that in basic or neutral, the antibacterial activity of HDMC was increased as the degree of quaternized increased; But in acid, the antibacterial activity of HDMC was declined as the degree of quaternized increased。
  • Effect of Thermodynamic Performance on Electrochemical Hydrogen Properties of Ball Milling CeMg12+100%Ni Alloys
    . 2012, 43(17): 22-0.
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    The CeMg12+100%Ni alloy samples were prepared by ball milling technology. Different ball-milled duration can affect directly microstructure and electrochemical performances of ball milling CeMg12+100%Ni alloys. The paper investigated mainly the electrochemical properties and intrinsic causes of alloy samples, which were synthesized at different ball-milled time, from the view of thermodynamics. The result showed that prolonging ball milling duration enhanced remarkably the glassing formation ability of ball milling CeMg12+100%Ni alloys, improving electrochemical discharge capacity. On the other hand, hydride phase after nanocrystalline and amorphous phase absorbed hydrogen possesses nanocrystalline and amorphous scale, which reduces hydride stability to some degree, accelerating markedly electrochemical discharge reaction.
  • Effect of electric field on ferroelectric properties in lead-free (Ba0.97Ca0.03)(Ti0.82Zr0.18)O3 ceramics
    ; ;;Jia LIU;Xue-Liang YANG;;;De-Jun Li
    . 2012, 43(17): 23-0.
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    The (Ba0.97Ca0.03)(Ti0.82Zr0.18)O3 ceramics were prepared by sol–gel technique. The evolution of the ferroelectric hysteresis loops was analyzed at frequencies ranging from 0.01 to 10 Hz and in a field of 1-8 kV/cm. The results show that the electric field and frequency dependence of hysteresis loops are obvious. At low field, coercive field (Ec) decreases monotonically with frequency increasing, and remanent polarization increases at low frequency. But at high field, Ec increases monotonically with frequency increasing, and the evolution of the hysteresis loops is not obvious with different testing frequency when the hysteresis loops become saturated.
  • Stability and controllability of Co-based amorphous ribbon with exchange bias behavior
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    . 2012, 43(17): 24-0.
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    Abstract：The CoFeNiSiB ribbons, which were annealed in longitudinal field at different temperature, exhibit a considerable exchange bias (EB) behavior. It is found that the magnetically harder crystalline phases play a main role in the appearance of EB behavior in the materials, due to the strong pinning effect. In this paper, the crystallization and microstructures of the samples were characterized via XRD and HRTEM. The hysteresis loops were measured using a ballistic galvanometer. The surface magnetic domains were scanned by the magnetic force microscope. The details of magnetic domains configuration has been analyzed based on the magnetic domain pattern. The results showed that there exist a critical field during the turning operation of the EB behavior by transverse impact filed (HT). It indicates that EB behavior is hardly changed when HT is smaller than critical field. In the other words, the EB behavior is stable. When the HT is larger than the critical field, the magnetic moment should be reconfigured abide by the principle of minimum free energy. In the process, the EB behavior can be effectively controlled by adjusting the HT.
  • Microwave absorbing property of the graphite foam concrete
    Xing-Wen Jiazhang ya jie;Qian jue shi
    . 2012, 43(17): 25-0.
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    The multi-functional property and lower cost are the main factors which decide the application prospects of building microwave absorbing materials. At 8GHz to 18GHz, the microwave absorbing property of the graphite foam concrete was tested by bow reflection method, and the effect of graphite dosage, foaming agent dosage and specimen thickness on absorbing property were tested at same time. The results show that the absorbing property of foam concrete increase gradually with the graphite content increasing, the percolation threshold of graphite in the graphite foam concrete is 15% of cement content. The reflectivity of foam concrete decreased gradually with the foaming agent dosage increasing. The absorbing property of foam concrete reaches high-point when the specimen thickness is 30mm, the reflectivity minimum value of foam concrete is –15.64dB when the graphite content and foaming agent dosage are 15% and 2.5% of cement content, respectively, and the total bandwidth is 3.0GHz when the reflectivity is below –10.0dB, at the same time thermal conductivity of foam concrete as low as 0.083 W / (m-1?K-1). Graphite foam concrete has good thermal insulation and absorbing performance, which can be used to build the roofing and wall by cast construction，and then the target of building electromagnetic radiation protection and building energy is achieved at the same time.
  • Study of performances of PAN fiber maded by fluidized preoxidation
    Xue-Ping GAO;
    . 2012, 43(17): 26-0.
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    The pre-oxidation experiment was carried out on PAN-based fiber by fluidization pre-oxidation technology, and the performances of preoxidized fiber under different technological schemes were studied by the oxygen content, bulk density, X-ray diffraction and Fourier transform infrared spectroscopy. Being 45 minutes Fluidization pre-oxidized, fiber oxygen content reaches 10.1%, bulk density reaches 1.38 g/cm3, the result of XRD, IR spectroscopy showed that the fiber complete the cyclization, dehydrogenation of chemical reactions and changes in physical structure, and ultimately heat-resistant trapezoidal structure was formed . The test results show that: by further optimization of the process, fluidized pre-oxidation technology could significantly shorten the pre-oxidation time, reduce production costs, ensuring the pre-oxidation quality synchronously.
  • Research on the Preparation of Self-crosslinking Styrene-acrylic Emulsion Paper Coating Agent and Its Film Performance
    Yi-ding SHEN;;
    . 2012, 43(17): 27-0.
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    Abstract: Self-crosslinking styrene-acrylic emulsion coating agent for paper was prepared by emulsion polymerization with styrene(St), butyl acrylate(BA), methyl methacrylate(MMA), acrylic acid (AA), hydroxyethyl acrylate (HEA) as raw materials, and the solid content of the emulsion was up to 40%. Effects of monomers concentration on the mechanical properties of film were investigated. It was found that the emulsion film was endowed with excellent mechanical property and thermal stability when w(MMA) = 11.5%, w(AA) = 6.9%, w(HEA)= 11.5% and m(St) / m(BA) = 1：2. And the average particle size of the emulsion was 128.9 nm with narrow particle size distribution.
  • The Influence of Formation Conditions on the Crystallization and Mechanical Properties of PAN Nascent Fiber
    Xie Ben
    . 2012, 43(17): 28-0.
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    The influence of the formation conditions including spinning solution temperature, coagulation bath temperature and spinning speed on the crystallization and mechanical properties of PAN nascent fiber, were investigated by means of XRD, tensile test and SEM. The crystallizability was weaken by lowering spinning solution and coagulation bath temperature, which improved the draw-ability of the PAN nascent fiber simultaneously with little influence on its breaking strength. And the adjustment of the coagulation bath temperature played a more marked effect. Increasing spinning speed was propitious to the drawing deformation for PAN nascent fiber, which effectively downsized the fiber’s fineness and comparatively improved its draw-ability.
  • Synthesis and Characterization of amide cross-linkers
    ;;;;;;Gong Chengbin
    . 2012, 43(17): 29-0.
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    Hydrogel beased on polyacrylamide is the hot topic in the materials science, the amide cross-linkers is one of the key factors that affect the properties of polyacrylamide. In this paper, a series of bis-substituted methacrylamide with different length chain were synthesized using alkyl diamines and methacrylatic chloride as the starting materials. The experimental conditions were optimized, and the chemical structures of the synthesized cross-linkers were confirmed by NMR，GC –MS and elemental analysis.
  • The influences of Yb3+ and Ho3+doping concentration and grain size on the luminescence properties of NaYF4:Yb3+,Ho3+upconversion materials
    HAO XIU LI
    . 2012, 43(17): 30-0.
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    Up-conversion (UC) material NaYF4 micron prisms were synthesized by hydrothermal method. The influences of Yb3+ and Ho3+ doping concentration and grain size on the luminescence properties of NaYF4 was studied detailedly. It is found that the emission was dominated by green light due to the low phonon energy, and the optimum doping concentrations for Yb3+ and Ho3+ are 25% and 1%, respectively, and higher Yb3+ and Ho3+ concentrations will cause the concentration quenching effect. The grain size increases with the decrease of NaF/NH4HF2 ratios in solution, leading to the increase of UC emission.
  • Study on the oxidation-curing mechanism of polycarbosilane fibers
    ma-tai DING;
    . 2012, 43(17): 31-0.
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    In order to investigate the oxidation-curing mechanism of polycarbosilane (PCS) green fibers, the products during oxidation-curing of PCS green fibers in different temperature zone were analyzed by IR、1H-NMR and GC-MAS, and the oxidation-cured PCS fibers were analyzed by IR. It was found that the major reactions occurred during oxidation-curing were the oxidation of Si-H bonds and the formation of Si-OH groups. And the condensation reactions were took place between the Si-OH groups to produce Si-O-Si linkages, which were responsible for curing. When the curing temperature was over 150℃, the Si-CH3 groups were also oxidized into Si-OH, further promoting the curing process. At the same time, the side chains of PCS molecule were decomposed to small molecule during oxidation-curing, forming big molecule by condensation of the Si-OH groups. The higher the oxidation-curing temperature, the higher the molecular mass of the products. It is essential to discharge the gas during the oxidation-curing, and the decomposed products can be avoided to be adhesion on the surface of the fibers and make the fibers sticking.
  • Synthesis of Nanometric LiFePO4 Materials in Liquid Phase: Effects of Precipitation Method and Calcination Temperature
    Yu XING ;;;;;;
    . 2012, 43(17): 32-0.
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    The intrinsic defects of solid-state synthesis make the derived lithium iron phosphate products difficult to be mass applied to the field of power grade Li-ion batteries. However, liquid phase synthetic routes including precipitation and hydrothermal synthesis are playing more and more important roles. Nanometric LiFePO4 materials are prepared by various precipitation methods. The samples were characterized by powder X-ray diffraction, field-emission scanning electron microscopy, and automatic charge-discharge measurement. The results are analyzed to select the best precipitation method. The mechanism involved in the performance differences among the prepared LFP materials are explained. The effects of calcination temperature on the average particle size, the particle size distribution, and the crystallite morphology are studied in details.
  • Study on characterization and thermal decomposition of ultra-fine carbonated lead Powder from Lead Paste
    Xin-Feng Zhu
    . 2012, 43(17): 33-0.
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    Lead carbonate was prepared from lead paste in spent lead acid battery with the hydrometallurgy process includes desulphurization, leaching, carbonation. The decomposition of lead carbonate was studied in inert atmospheres using differential thermal analysis and thermogravimetry (TG-DSC), scanning electron microscopy (SEM) and X-Ray powder diffraction (XRD). The graphs SEM show the product was hexaganal crystal and the size ranges from 0.5 to 5 μm. The four steps for thermal decomposition of lead carbonate yielded PbCO3?2PbO, α-PbO, Pb3O4, and β-PbO respectively, consistent with curve of TG-DSC. The shape of lead oxide was spheric and its diameter less than 0.5 μm.
  • Study on the synthesis of (Ti,W,Mo,V)CN composite powders by carbothermal reduction–nitridation in an open system
    ;;
    . 2012, 43(17): 34-0.
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    (Ti, W, Mo, V)CN composite powders were synthesized from oxides by carbothermal reduction–nitridation in an open system. The phase transition and microstructure evolution in the process were analyzed by XRD, SEM and so on. The results demonstrated that the synthesis of (Ti,W,Mo,V)CN with the following evolution sequence: TiO2 (anatase) →TiO2 ( rutile) →Ti4O7 →Ti3O5 →Ti(N,O) →(Ti，Mo…)N →(Ti,W,Mo,V)CN. We can get the composite powders with 0.11%C and 0.28%O in weight fraction.
  • Experimental Study on Smelting Reduction of MgO from Dolomite under vacuum
    ;Gao Jiao Cheng
    . 2012, 43(17): 35-0.
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    Calcined dolomite with appropriate Al2O3 and SiO2 as slag agents can form completely-melted slag at 1500 to 1600℃. The smelting reduction was carried out where MgO in the slag was reduced by ferrosilicon under vaccum. The influence of slag agent on reduction extent of MgO was studied，and the results show that reduction extent of MgO was improved by increasing the ratio of Al2O3/SiO2. The ideal composition of slag was 32.0%CaO-23.0%MgO- 35.0%Al2O3-10%SiO2. By carrying out and analyzing orthogonal experiment of smelting reduction, the impact fators order of reduction extent of MgO was reaction temperature，ferrosilicon addition, reduction time，CaF2 addition. Under such optional condition of reaction temperature of 1600℃, n(Si)/n(2MgO) ratio of 1.2, reduction time of 2h and adding CaF2 of 3%, reduction extent of MgO was achieved up to 97.3%.
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