20 December 2016, Volume 47 Issue S2
    

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    Review & Advance
  • SU Xing,PENG Yunfeng
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    Super-hydrophobic is an important surface properties of the plants and animals surface in nature. It has great potential because of its high contact angle and low roll angle, with self-cleaning and reconciliations interfacial adhesion and friction, and it has caused widespread concern in surface engineering and precision engineering. This paper summarizes the development of superhydrophobic theoretical models in recent years and the main factors affecting of superhydrophobic property, starting with the classical theory of energy, application Young's equation, the theoretical models of Wenzel and Cassie-Baxter, and their transition condition to explain the formation mechanism of superhydrophobic surface, and discussing the contact angle of hysteresis theory and the theory of the contact line in superhydrophobic surfaces; then summary of the geometric topology structure of the surface and its parameters effect of super hydrophobic properties based on Wenzel and Cassie-Baxter two theoretical model; final analysis the prospects for superhydrophobic future.
  • DU Lei,TANG Qiang, LIN Xiuzhou, ZHANG Guohu, CHENG Min,
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    Nano-pore super thermal insulation material is a kind of ideal thermal insulation material. Performance characteristics and application prospects of the nano-pore super thermal insulation materials were summarized. Preparation processes and latest research progress of SiO2 nano-porous super thermal insulation materials were reviewed. Research methods and latest research progress about modification techniques of SiO2 thermal insulation materials were discussed. Various characteristics and influence factors of the preparation process were analyzed. At last, the main problems of current research and the development direction in the future were pointed out.
  • YAN Tao,PAN Zhijuan
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    Traditional metal and semiconductor strain gauges usually possess of low sensitivity, toughness, and elongation, which limit their application in the filed of high strain. So it has become an important development direction to enhance the gauge factor and strain properties of strain sensor, a flexible carbon-based nanocomposite strain sensor provided an effective solution to this problem. This paper introduced the research status of the carbon-based nanocomposite material strain sensor, including the effect of concentration, orientation, and dispersion of carbon-based nanomaterials in the polymers on the performance of the strain sensor, the preparation methods and strain sensing property of different matrix composite strain sensors, and their advantage and disadvantage, which would provide a reference for the development of carbon-based nanocomposite strain sensor.
  • YU Xiaoyan, HE Qinyu
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    SnSe is a new thermoelectric material which just emerges in recent years. Sinceit haslayered structure, very low thermal conductivity and high ZT, it is a prospect of thermoelectric materials for application in the middle and low temperature range. Thus much attention is paid to optimize its thermoelectric performance. In this review, the SnSe’s molecular structure, band structure and transport properties, thermoelectric characteristics were summarized, the advantages and disadvantages of different processing methods were analyzed; the factors which affected its thermal performance and industrial application were discussed. At last we try to put forward to using the advantage of "Mosaic" crystal to optimize the SnSe’s thermoelectric performance. The purpose of this review is to help readers to have a comprehensive understanding of SnSe’s structure, transport properties and thermoelectric characteristics. Meanwhile, for researchers, we aid to provide a possible direction which can improve the SnSe’s thermoelectric performance and search for thermolelectric materials which can gain high ZT.
  • ResearchandDevelopment
  • JIANG Hong,FAN Zhiguo,LEI Junxiang,XIE Chaoying
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    Commercially pure Ti was prepared by multi-pass ECAE at 400 ℃ via route Bc. The microstructures evolution were characterized by transmission election microscopy (TEM).The electrochemical corrosion behaviors in Ringer’s solution were investigated by electrochemical impedance spectroscopy (EIS) measurement. After eight-passes ECAE treatment, the microstructure becomes more homogeneous and the fraction of fine equiaxed grains increases, smaller than 0.5 μm.The corrosion resistance of CP-Ti sample with different pass ECAE treatment increases in the order of zero-pass, two-passes, one-pass, four-passed and eight-passes. The eight-passes ECAEed CP-Ti have the best corrosion resistance. The corrosion resistance of two-passes sample is not inferior to one-pass although the microstructure is refined. The crystallographic plane parallel to the surface of ECAEed samples is changed from (011-0) plane in one-pass to (112-0)high index plane in two-passes and results the reduce of corrosion resistant performance. It indicates that the electrochemical corrosion behaviour of CP-Ti is effected simultaneously by grain size and texture during multi-pass ECAE process.
  • HUANG Zongze,LUO Dongmei,ZENG Fanbo,YUAN Xizhi
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    In this work, we studied the roasting process of calcium vanadium compound with different additives and different temperature conditions. It is found that, the reaction steps with CaO additive is as the same as those with CaCO3. The first step is that when the temperature is 625 ℃, V2O5 reacts with calcium to form a large amount of CaV2O6 and some of CaV2O6 starts to react with calcium. After then, lots of Ca2V2O7 formed with the reaction of CaV2O6 and calcium. The difference between two additives is that with CaCO3 additive, both of CaV2O6 and Ca2V2O7 are formed during the initial reaction and the temperature to react next step is 708 ℃. While with CaO additive, there are only a few Ca2V2O7 formed and the subsequent reaction temperature is 777 ℃.The experimental data shows that the leaching rate of two calcium additives are 73% and 94.5%, respectively. By analyzing the micro structure of reaction products, we found that with the CaO additive, the products become so compact that it affects the reaction with CaO. When the additive is CaCO3, it is a favorable response to the mass transfer that CO2 gas, formed during the reaction, diffuses outward and tiny interspace form inside the materials. Moreover, increasing the reaction area makes the reaction speed faster and reaction more entirely conducted. Therefore, it will get much better to the reaction in the roasting process when the additive is CaCO3.
  • GENG Xiezhen,ZHOU Yongjiang,HUANG Lihua
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    The Tetrapod-like ZnO whisker (T-ZnOw) with unique three-dimensional and tetrapod-shaped structure has characteristics such as material strengthen, antistatic,and microwave absorption. The composite absorbent was prepared by mixing T-ZnOw with phenolic resin.The surface of quartz glass fiber was coated with the composite absorbent to prepare a new type of radar absorbing fiber. The research shows that T-ZnOw as a dielectric loss absorber can effectively improve the wave absorbing property of quartz glass fiber. The resistivity of fiber can influence the absorbing property of fiber, and the ideal fiber resistivity is at 0.21 Ω·cm. the treatment temperature can influence the resistivity of fiber and the fiber resistivity is at 0.21 Ω·cm, when the treatment temperature is 850 ℃. Compared with the continuous coating, periodic discontinuous coating can improve the low frequency absorption and broadband wave absorbing of glass fiber.
  • LIU Zuohua, LIU Min, DU Jun, TAO Changyuan, FAN Xin
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    Brominatied chloroprene rubber(BCR) was prepared by Modification process of chloroprene rubber(CR) via HBr/H2O2, graphene oxide(GO) reinforced brominatied chloroprene rubber was prepared by means of mixing(O-BCR). The structure of samples was characterized by SEM,FT-IR,UV and detected the mechanical properties. Results showed that.the graphene oxide well dispersed in BCR matrix, the free radical graft copolymerization of —COOH and —OH on the surface of graphene oxide onto BCR,which improve the mechanical properties of brominated neoprene Compared with BCR:the mooney viscosity of O-BCR improved 161 percent; the tensile strength of O-BCR improved 31 percent; the stretching strength of O-BCR improved 46 percent; the breaking strength of O-BCR improved 11 percent; the permanent deformation of O-BCR improved 33 percent.
  • QI Tonggang, ZHANG Zhanhui, GUAN Doudou, PENG Weikang, HUANG Zhiliang
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    The thermal degradation is one of the key problems that restricting the working properties and applied range of Sr2MgSi2O7∶Eu2+,Dy3+ long afterglow luminescent materials. To clarify the thermal degradation mechanism of Sr2MgSi2O7∶Eu2+, Dy3+, a heat-treatment process at different temperature was carried out, the afterglow properties and luminescent spectra were characterized, and the effects of heat-treatment temperature on the afterglow properties and luminescent intensity were studied. The results revealed that the afterglow properties had no significant change, and the emission intensity decreased with the increasing temperature, when the heat-treatment temperature was lower than 600 ℃. The afterglow properties degraded significantly when the heat-treatment temperature was higher than 600 ℃, and the emission intensity increased at first then decreased with the increasing temperature. A maximum value was reached at a temperature of 900 ℃. The root cause of these phenomena was the weaken capacity on electron capture of trap level. Based on the relationship of afterglow property degradation and emission intensity changes, a thermal degradation mechanism about the heat damage of trap level was proposed.
  • CUI Boxuan,YU Dapeng,YU Meng
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    The effects of attaching nanobuds on the thermal conductivity SWCNT are investigated using the non-equilibrium molecular dynamics (NEMD) simulation. Results show that attaching nanobuds will decrease the thermal conductivity of SWCNT, and the effect of attached C60 molecules on the thermal conductivity of SWCNT becomes smaller with the increase in the number of attached C60 molecules. Also, NEMD simulations and applied temperature gradient are employed to study the intra-tube junction thermal resistance and inter-tube junction thermal conductance of the nanobud formed by pressure method. Compared with previous work on X-junction, it is certain improvement on thermal conductivity of interconnected network of carbon nanotube when nanobud junctions are involved.
  • WU Jianhua, ZHOU Jixue, TANG Shouqiu, WANG Jinwei,
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    The effects of cooling rate on the microstructure and tensile properties of as-cast A356 alloy were investigated. The results show that the secondary dendrite arm spacing decreased with increaseing of cooling rate. At the same time, the morphology of eutectic silicon in A356 alloy was changed from coarse needle to fine short-rod or particles, and thus resulting in increase of the tensile properties. The tensile strength of 205 MPa, the yield strength of 143 MPa and elongation of 10.4% was obtained for A356 alloy at the high cooling rate. Therefore, controlling cooling rate can refine the microstructure and improve the mechanical properties of as-cast A356 alloy.
  • WANG Hongyu, HUANG Aiguo, YUAN Xiaoming, CHENG Man, DING Rui
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    To explore welding performance of Ti-V-Cr burn-resistant titanium alloy, welding repair of Ti-25V-10Cr burn-resistant titanium alloy sheet with a simulative non-through crack was carried out by adopting laser welding, and effects of laser welding on microstructure, microhardness and tensile property were investigated. Results show that the welding seam microstructure is coarse as-cast β columnar crystals, and the relative growth interface of β columnar crystals on both sides is visible in welding seam center. The heat-affected zone (HAZ) microstructure remains single β equiaxed crystals, and only some grains closed to the fusion line is coarsening. Meanwhile, the microhardness of welding seam reaches to about 570 HV that is 1.78-fold of the one of base metal, but the microhardness of HAZ changes a little. Moreover, the tensile strength of welded joint is about 405 MPa that is only 40% or so of base metal. The fracture of the tensile samples occurres near the welding seam center, and the tensile fracture presents a mixed rupture and the brittle rupture is prominent. It can be concluded that the welding performance of Ti-25V-10Cr burn-resistant titanium alloy will be a main restricting factor for its widespread application.
  • PENG Long,HU Yuebin, ZHANG Dagong,SU Hai,HU Yun,LI Lezhong
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    For use in microwave low temperature co-fired ceramics (LTCC) technology, the hexagonal M-type strontium ferrites (SrFe12O19) with additives of Bi2O3, B2O3, CuO, MoO3, PbO, and Al2O3·2SiO2·2H2O as sintering aids were prepared by solid phase method in this paper. The results show that the additives provide a significant effect on the crystal structure, compactness, direct-current resistivity, and static magnetic properties for the ferrites. The crystal phase composition can be improved by adjusting the amount of Bi2O3, CuO, and PbO and the SrFe12O19 single phase structure is successfully obtained. Appropriate addition of Bi2O3 and PbO separately increases the compactness to a value higher than 94%, which is beneficial to enhance the saturation magnetization Ms and intrinsic coercivity Hcj. It is suggested that the SrFe12O19 ferrites sintered with 3wt% Bi2O3 can provide good electrical properties with direct-current resistivity ρ of 0.42×108 Ω·cm and large magnetic properties with Ms of 60.7 A·m2/kg and Hcj of 347.2 kA/m, which possess a potentiality for applying in microwave LTCC circulators.
  • WANG Yaxi,FU Min,WU Siwei
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    SrCO3 composite photocatalyst was prepared in air by calcinations of Sr(OH)2, which was synthesized via a method of precipitation by SrCl2. The phases and structures of the products were investigated by powder X-ray diffraction (XRD) and Fourier transform infrared spectroscopy(FT-IR), surface structure and composition were analyszed by X-ray photoelectron spectroscopy (XPS) and the samples’ light absorption and fluorescence properties were characterized by UV-vis diffuse reflection absorption spectrum and photoluminescence spectra (PL). The photocatalytic property of SrCO3 composite photocatalysts was evaluated by photocatalytic oxidation of methylene blue (MB) under visible-light irradiation. Results showed that with the irradiation time of 150 min, the photodegradation efficiency of MB by the SrCO3 composite photocatalyst, which was calcined under 500, 600, 700 and 800 ℃, reached 98.7%, 96.3%, 96.0% and 95.2% respectively.
  • AI Chunpeng, ZHAO Xiaofeng, BAI Yinan, FENG Qingmao, WEN Dianzhong
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    Preparation of ZnO thin films based on RF magnetron sputtering, by using X-ray diffraction (XRD), field emission scanning electron microscopy (SEM) to analyze ZnO thin films which were manufactured under various sputtering power, time and annealed at various temperature. The results show that the preferred orientation of deposited ZnO thin films was (002) plane, and enhanced with increased sputtering power and annealing temperature. We analyzed I-V characteristics of the ZnO thin films. The results show that the ZnO thin films which its thickness is 92 nm has resistive switching characteristic, and the on-off ratio was upto 104.
  • WANG Xing, LI Sunfeng, XU Yanli, YANG Hanbiao, LIU Xueting, WEI Fengyu
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    In this paper, the emulsification-chemical crosslinking method is successfully used to prepare the porous composite microspheres under the emulsion polymerization situation with chitosan, glutaraldehyde and dibutyl phthalate acetate (DBP) as raw material, cross-linking agent and hole agent, respectively, and the prepared composite microspheres will be applied as nutrient support for the roots of plants. Through the single factor study,the best preparation conditions for hole formation of composite microspheres are obtained:chitosan solution concentration is 1.8- 2.0wt%,O/W ratio is 5∶1,the stirring speed is 900 r/min,emulsification temperature is 45 ℃,the volume ratio of DBP to O/W is 1∶7.5, and the volume ratio of glutaraldehyde with 50%(v/v) concentration to O/W is 1∶40. Scanning electron microscopy (SEM) was used to analyze the morphology and structure of the composite microspheres. Transmission electron microscopy (TEM) and element mapping were supplied to make certain that the N,P,K containing compound fertilizer is successfully packaged in chitosan microspheres. The slow release properties of the composite microspheres were tested by elemental analyzer and ICP (inductively coupled plasma). The results prove that the spherical structured degree of composite microspheres is good, most of particle size is around 50 μm, microsphere surface is rough and part of the structure is with pore. The release rule of composite microspheres conforms to the Higu-chi skeleton model, release gradually becomes stable after 132 hours, and the prepared composite microspheres have good slow release effect.
  • WANG Fashe
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    Single-phase Pr2CuO4-xFx and Pr2CuO4-x have been obtained with a small amount of impurity phases. For the samples of Pr2CuO4-xFx, superconductivity transitions are observed in the range of 0.04≤x≤0.16 and Tc is 26 K. The samples of Pr2CuO4-x can not achieve superconductivity only by adjusting the oxygen content. By the comparison of different effects of the oxygen content on structure and magnetic properties, it is found that in Pr2CuO4-xFx samples the reason of superconductivity realization is free carrier introduction, while for Pr2CuO4-x the reason why the superconductivity does not realize is that oxygen vacancies do not appear in the same oxygen position. The relative mechanism was discussed.
  • WANG Jianhua, ZHU Baoku
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    In order to construct a charge separation layer,supercritical carbon dioxide (scCO2) was used as reaction medium in synthesizing SMA-g-DMEN copolymer, then the charge modified PSf membranes were fabricated by quaternization crosslinking between N,N-Dimethylethylenediamine and α,α′-Dichloro-p-xylene. Chemical compositions, morphologies, hydrophilicities and charge properties of the membranes were investigated by FTIR-ATR, SEM, water contact angle and Zeta potential, respectively. The results show that the membranes exhibit good hydrophilicity, there are two isoelectric points, at pH from 4.5 to 7.6, the modified membranes show positively charge properties. At the same time, when the copolymer concentration changes between 0.010wt% and 0.0125wt%, at 0.3 MPa, the water flux and the rejection of MgCl2 is 35-40 L/m2·h and 60%-75%, respectively. It demonstrates that the membrane is endowed with charge property by quaternization crosslinking and has a salt rejection property by changing pH.
  • FENG Guolin, LI Juan
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    Based on self-flux method, the single samples, with high quality, of Tl0.4K0.4Fe2-ySe2-xSx system were prepared successfully. The effects of S-Se substitution on superconductivity in the Tl0.4K0.4Fe2-ySe2-xSx system were studied in detail. When S doping x is from 0.8 to 1.0, there may be quantum critical phenomenon in the single crystal samples of Tl0.4K0.4Fe2-ySe2-xSx.
  • LIU Yanhong, WANG Baodong, SUN Qi, XIAO Yongfeng,
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    The major composition of white mud by-produced from alumina extraction from coal ash “direct acid-leaching method” developed by Shenhua Group, is SiO2 which accounts more than 70%. The White Mud has been considered as potential silicon based materials. The chemical and physical properties of White Mud have been analyzed. The iron methods have been introduced including carbonation process, manganese sand filter, and membrane separation technique. It is concluded that there are two main sources of iron in White Mud, one is Fe2O3 and FeO which is not dissolved during the “one-step acid-leaching method” process, and would not dissolved in the hot concentrated NaOH solution. The other is FeCl3 and FeCl2 which came from the dissolved oxide of iron in the “direct acid-leaching method”, and would react with hot concentrated NaOH solution to FeO-2 andFeO2-2 during the desilicification from White Mud. After dehydration, FeCl3 and FeCl2 reacted to Fe(OH)3 and Fe2O3 which react with hot concentrated NaOH solution difficultly and so partly exist in nanoparticles. In the experimental conditions, the leaching rates of SiO2 in dehydrated White Mud is above 70%, the concentrations of silicon and iron are about150.0 and 182.2 mg/L respectively, which reduced to about 30 mg/L (FeOSi(OH)32+) by carbonation, converted into Fe(OH)3 particles. Part of Fe(OH)3 particles precipitated with silicate, the other part existed in the solution as nanoparticles, which could be rarely removed by manganese sand filter, and membrane separation technique. The iron concentration of SiO2 produced by two-step-carbonation is 227 mg/kg.
  • WANG Jian, YU Yuan, GE Mingqiao
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    The high elastic luminous fabrics is coated by self-made high elastic luminous finishing agent. The luminescent performance, wash resistance, tensile property, shape retention and surface morphology of the high elastic luminous fabrics are studied. The results show that most of luminescent materials on the surface of luminous elastic fabric can be coated inside polymer film. The initial brightness of high elastic luminous fabric is 1.643 cd/m2, and initial brightness of after washing luminous fabric can still be 1.445 cd/m2. The tensile properties of the luminous elastic fabric slightly lower than the original. But it has good appearance of shape preserving performance and anti bending property.
  • Process& Technology
  • XU Li, GONG Xuehai, SHENG Peng, CHEN Xin, HAN Yu,LIU Shuangyu,
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  • LUO Bin, WANG Yanjie
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    Elastic modulus of ionic polymer-metal composite material is closely related to the water content within the material, which is decided by different humidity. The tensile way is not accurate. resonance method to measure the elastic modulus of the ionic polymer-metal composite during the dehydration process in different time through formula variation is effective. By establishing the relationship between the environment humidity and moisture content of the material, the elastic modulus of the material under different humidity conditions is obtained. This method is simple and feasible, and can solve the problem of measuring the elastic modulus of ionic polymer metal composite materials under different humidity conditions.
  • TONG Wei, PEI Jiuyang, CHEN Minghai, LIU Ning, XU Wenlei
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    Graphite flakes(Gf)/aluminum composites were prepared by pressure infiltration method. The influence of graphite flakes content on thermal properties of composites was investigated, and its microstructure and thermal properties of the composites were analyzed. The results showed that graphite flakes could increase the in-plane thermal conductivity and decrease the coefficient of thermal expansion and density of the composite. The in-plane thermal conductivity of composite increased from 234 W/(m·K) to 403 W/(m·K) by the graphite flakes volume fractions increasing from 23.9% to 73.4% in the composite.
  • ZHANG Junmin,WEN Ming,TAN Zhilong,WANG Chuanjun,SHEN Yue,
    YI Wei,GUAN Weiming, LI Yanqiong
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    Because of low resistance coefficient, good thermal stability and oxidation resistance,WTi alloy has been successfully applied to the diffusion barrier layer of semiconductor device.So far, The target used in China semiconductor industry is mostly imported from abroad. Therefore, by studying the relationship between preparation process and the performance of target, to get high density, high purity titanium, and less β1(Ti,W) phase WTi alloy.W and Ti mixed powders with different particle sizes were obtained by the planetary ball milling. The WTi10 alloy was prepared by vacuum hot pressing. X ray diffraction (XRD), scanning electron microscope (SEM) were used to analyze morphology of the alloy and the particle size of the composite powder and the structure. The density and impurity cotent were analyzed by the method of drainage method and ICP test. The results showed that in the temperature 1 200 ℃, 30 MPa pressure vacuum hot pressing conditions, the WTi alloy have been formed body centered cubic beta phase WTi solid solution. The powder mixed time have no effect on the peak position and peak strength of WTi solid solution. But powder mixed time affect alloy microstructure morphology greatly, longer duration of mixed powder, rich titanium phase β1 showed a trend of increase after the first reduce,mixed powder samples of 3 hours get rich Ti solid solution phase area at least, optimal performance, the density of alloy achieves 99.48% of theoretical density, the purity is more than 99.97%. WTi alloy prepared by this method can be used for the preparation of the diffusion barrier layer by magnetron sputtering. The above research provided basic data for the research of vacuum hot-pressed magnetic WTi target.
  • ZHANG Yajun, YAO Zhongping, JIANG Zhaohua
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    Hierarchical dendritic structure ZnFe2O4 was prepared by electrochemical reduction and thermal oxidation method and the influence of thermal oxidation on the structure and photocatalytic activities for water splitting was researched in this work. X-ray diffractometry and field-emission scanning electron microscopy were used to characterize the crystal structure, size and morphology. UV-Vis diffuse reflectance spectra were acquired by a spectrophotometer. Photocatalytic activities for water splitting were investigated under Xe light irradiation. The results show that the proper increase of the temperature are liable for the growth of hierarchical dendritic structure oxide. If the sintering temperature goes too high, the dendritic structure cracks and breaks off. When the temperature is 200 ℃, the photocatalytic activity of the sample is 43.5 μmol/(h·g). Increasing the temperature to 350 ℃/450 ℃, the photocatalytic activity is 70.5 and 75.5 μmol/(h·g), respectively. The sintering atmosphere does not only influence the morphology of the sample, but also change the crystal structure. The crystal structure of the sample sintered in high purity nitrogen atmosphere, is composed of ZnFe2O4, ZnO and FeZn8.87. Besides, its photocatalytic activity is obviously worse than that of the sample sintered in air.
  • LIU Yifan, CHEN Wenqian, LIU Minghua
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    The foam glass was produced through the foaming process, using waste glass as the primary raw material, calcium carbonate which will break down into carbon dioxide in the molten state at high temperature as foaming agent, boric acid as fluxing agent, sodium phosphate as foam stabilizer. With the aid of XRD, ESEM and other instruments helping characterize and analyze the microstructure and phases, the influences of sintering temperature on foam glass were examined including the pore structure, apparent density, thermal insulation, etc. The results demonstrated that the porosity of foam glass increased with the rising of temperature, and the gas escaped and the pores shrank when it reaching a certain temperature. The apparent density and flexural strength displayed the downward trend. The sample has relatively optimum properties especially in thermal insulation at 810 ℃ with evenly distributive moderate aperture whose apparent density was 297.62 kg/m3, flexural strength was 1.02 MPa, volumetric water absorption was 17.92%.
  • WU Yingfeng
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    With the continuous development of the copper clad laminates(CCL), which is the base material of printed circuit board (PCB), also more and more high requirement to the fillers of CCL. Silicon powder as one kind of inorganic fillers, has been more and more widely used, including spherical silica powder has more compatibility with resin, improve the heat resistance of the copper clad laminates. Vibration grinding classification system is used to produce kinds of spherical silica powder.
  • NI Jing,LIANG Ying,CAI Guangyi,DONG Zehua
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    A kind of phosphorus-doped composite was prepared by a simple hydrothermal method with poly (ethylene glycol)-block-poly (propylene glycol)-block-poly(ethylene glycol) polymer (P123) as soft template, physic acid as phosphorus source and glucose as carbon source. The composite was then etched by KOH under high temperature to form a three-dimensional microporous structure. SEM and TEM observations shows a typical feature of multi-layer dense hierarchy of micropores with relatively large pores outside and micropores inside the composite, FT-IR and XPS analysis indicates a successful doping of P element. Electrochemical tests indicate that the P-doped porous composite has a further high specific capacity up to 235 F/g than the un-doped carbon materials which is only 182 F/g in 1 mol/L KOH. Besides, it retains excellent charge-discharge reversibility with high capacitance retention up to 90% even after 4 000 cycles. The electrochemical results demonstrate that phosphorus doping can obviously improve the hydrophilicity of electrode surface and pseudo capacitance, making it possess better electrochemical characteristics.
  • XU Hongfei, CHEN Lin, YU Nanjie, DU Yihang, LIN Jun, DU Xiaoze
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    Hexagonal boron nitride (h-BN) and maleic anhydride grafted polypropylene(PP-g-ma) were simultaneously blended with polypropylene (PP) to fabricate thermally conductive composites using a twin-screw extruder. The microstructure of the composites was analyzed with X-ray diffraction (XRD) and scanning electron microscope (SEM). The crystallization properties, mechanical properties and thermal properties of the composites were investigated. The results show that the crystallization is improved, the elongation at break and tensile strength enhanced, and the thermal conductivity improved significantly, because of strong interaction between h-BN and PP chained by PP-g-ma. When the content of h-BN is 30wt%, the thermal conductivity of the PP/h-BN composite containing additional PP-g-ma is 1.08 times to the value of PP/h-BN composite and as high as 2.3 times to that of PP.