15 October 2014, Volume 45 Issue 19
    

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  • A Study of the mechanism of silica reinforced silicone based thermoelastic analysis
    . 2014, 45(19): 1-0.
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    Abstract: The mechanism of silica reinforced polymethylvinylsiloxane(PMVS) were investigated using dissolution/swelling experiment, thermoelastic measurements and thermoelasticity theory. Dissolution/swelling experimental results have shown that the chain entropy decrease plays an important role in reinforcing PMVS. The mobility of molecular chain in PMVS network is lowering with the increasing of the silica content. Thermoelastic analysis indicated that the mobility of a small amount of the segment part of which the mobility is completely restricted in the vulcanizing PMVS/silica network structure increased in a conditions of a given stretch, increasing temperature, so that the internal energy of the molecule chains can increase the contribution to the total stress (fe/f), and the contribution is gradually increased with the increase of the silica content. In other words, entropy change leads to the reinforced PMVS by silica, as well as the internal energy (especially at low extension ratio condition).
  • Preparation of coated Starch/Fe0 by using rheological phase reaction method and reaearch on reaction kinetic of Cr(Ⅵ) removal in water
    Chuang JIAO
    . 2014, 45(19): 3-0.
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    The coated nanoscale zero-valent iron (coated Starch/Fe0) is synthesized with starch as coating agent, and by using rheological phase reaction method. The effection of sample dosage, pH values, initial Cr(VI) concentration and Cu2+ concentration on removal rate of Cr(VI) , and the reaction kinetics are investigated . The reaction mechanism is researched about the removal of Cr(VI) with coated Starch/Fe0. The sample is fully characterized by means of XRD, SEM and TEM. The experimental results indicate that the removal rate of Cr(VI) is 100% when the sample dosage is 0.6 g/L, the pH values is 5, and the initial Cr(VI) concentration is 10 mg/L.Cu2 + has promote role on the removal of Cr (VI) when the Cu2+and Cr (VI) coexist in the reaction system . The reaction kinetic follows pseudo-first-order reaction model.
  • Effect of the core size of the core/shell structured PS/SiO2 composite abrasives on oxide-CMP behavior
    . 2014, 45(19): 4-0.
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    Organic-inorganic composite materials combine the advantages of the two components, and exhibit novel structures and properties. Core/shell organic/inorganic composite microspheres as a novel abrasives have an important application in efficient and damage-free polishing due to their uniform non-rigid mechanical property. In this work, a series of polystyrene (PS) microspheres with various sizes were synthesized by surfactant-free emulsion polymerization method and then coated with silica nanoparticles by sol-gel process to obtain the core/shell structured PS/SiO2 composites. The as-synthesized samples were characterized by FT-IR, FESEM and TEM technique. The effect of the core size of the PS/SiO2 composite abrasives on oxide-CMP behavior were investigated by AFM. The results indicated that the size of the obtained PS microspheres ranged from 200 to 600 nm. The shells of the composites were composed of SiO2 nanoparticles (5-10 nm), and the shell thickness was 10-15 nm. The root mean square (RMS) roughness and material removal rate (MRR) values of the polished wafers decreased with the decrease of the PS core size. After CMP, with the decrease of the core size, the MRR was decreasing, while the RMS of the wafer surface almost retain constant. For the composite of the core size of 210 nm, the RMS and MRR values were 0.217 nm and 126.2 nm/min, respectively. We proposed that the core/shell organic/inorganic composites could be considered as micro-polishing pads, which were covered with inorganic nanoparticles. The model used to explain the results take into account both the total number of active abrasives and the indentation depth of single SiO2 particle in the shell. Besides, the effect of the PS cores on the behavior of composite abrasives was discussed.
  • The Preliminary Investigation of Hydrogen Plasma Assisted Solid Phase Crystallization Polycrystalline Silicon Film
    Zheng-Peng LIU Juan LI
    . 2014, 45(19): 5-0.
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    In this paper, a novel technology of hydrogen plasma assisted solid phase crystallization polysilicon was proposed. This crystallization technology can not only reduce the crystallization time but also passivate defects in the poly-Si thin films effectively. We compared the H-SPC with traditional SPC firstly, and then, investigated the influence of process conditions on the quality of the resultant polysilicon. In addition, we studied the physical mechanism of this crystallization technology.
  • Study of acrylonitrile-butadiene-styrene as β-nucleating agent for isotactic polypropylene and the properties of ABS/iPP composites
    An-Ran ZENG Yu -Ying ZHENG
    . 2014, 45(19): 6-0.
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    ABS/iPP composites were prepared by extrusion processing and its crystallization, mechanical properties were studied. The result of WAXD showed that β-modification was induced with the help of ABS along β(300) lattice pland, and α-modification was restrained. When the content of ABS was 5wt%, the relative content of β-crystal in iPP was 0.45, and the crystallinity was 66.94%. The results also showed that the relative content of β-crystal was hard to increase continually, because the crystalline rate was too fast for iPP chain segment to adjust its chirality to form β-crystal. It was found from DSC that the crystalline temperature and rate of iPP was increased with the adding of ABS, and the melting peak of β-crystal was appeared in the melting curve of ABS/iPP composites. It was observed in POM figures that β-crystal of iPP chain segment was crystallized belong ABS chain segment. In addition, the mechanical properties and heat distortion temperature were increased. In conclusion, ABS can be used as polymeric β-nucleating agent for inducing iPP into β-modification and improving the properties of iPP.
  • Microstructure and porperties of amorphous and nanocrystalline coatings prepared by arc surfacing welding
    . 2014, 45(19): 7-0.
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    A kind of surfacing welding electrode with iron-based amorphous alloy Fe41Co7Cr15Mo14C15B6Y2 weld core and low hydrogen coating was welded on the surface of Q235 steel to obtain two types of amorphous/nanocrystalline coatings. Different proportions of amorphous and nanocrystalline coatings were fabricated by changing the welding parameters (heat input). XRD /SEM / EDS were used to explore the structural transformations of the coatings and the proportion of nanocrystalline phases were determined; crystallization characterization, hardness and wear resistance were also studied . The experiments results present that the amorphous/nanocrystalline coatings has good metallurgic bonding with the substrate, the content of amorphous phase reaches to 47.44% and the sizes of nanocrystallines are 10~50nm, the hardness of the surfacing layer is high as 1226HV1 and the wear resistance is 8 times higher than that of Q235 steel.The crystallization activation energies of the two surfacing layers are seperately Ex(150A)=107.476kJ/mol, Ex(160A)=58.104kJ/mol. Furthermore, as the heat input increase, the proportion of the amorphous phases decrease and the grain sizes of the nanocrystalline coarsen, the crystallization temperature, thermal stability, hardness and wear resistance also decrease.
  • Study on the treating effect of midium-frequency magnetic pulsing of amorphous Fe52Co34Hf7B6Cu1 alloy
    . 2014, 45(19): 8-0.
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    In this paper, the amporphous specimens Fe52Co34Hf7B6Cu1 were treated by medium-frequency magnetic pulsing. The treatment conditions were as follows : the field intensity and acting time were constant (250Oe、10min), the pulsing frequency were 500,1500 and 2000 Hz respectively. The microstructural change of specimens after magnetic-pulsing were observed by MS, XRD and TEM technique. The soft magnetic properties of specimens treated by magnetic-pulsing were tested by VSM. The results show that the medium-frequency magnetic pulsing(1500Hz、250Oe、10min) can evidently improve the soft magnetic properties of Fe52Co34Hf7B6Cu1 amorphous alloy.
  • Improving the conductivity and thermal stability of polymer electrolytes for lithium-ion battery with hybrid poly(phenylsilsesquioxane) spheres
    JU YaQing
    . 2014, 45(19): 10-0.
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    The organic-inorganic hybrid poly(phenylsilsesquioxane) spheres (PPSQ) were prepared and the structure of PPSQ was confirmed by transmission electron microscope (TEM) , thermogravimetry analysis (TGA), the X-ray diffraction analysis (XRD) and X-ray photoelectron spectroscopy (XPS). The interaction between PPSQ and poly(methyl methacrylate-vinyl acetate) was investigated by Fourier transform infrared spectra (FTIR) and XRD. The composite electrolytes using poly(methyl methacrylate-vinyl acetate) and organic–inorganic hybrid spheres of poly(phenylsilsesquioxane) were prepared. The results indicated that PPSQ enhanced the ionic conductivity and thermal stability of prepared composite electrolyte.
  • Investigation on Stability and Thermodynamic Properties of γ-TiAl Doped with Zr
    Qing-Gong SONG
    . 2014, 45(19): 11-0.
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    The geometry structures, total energies, binding energies, photon dispersions and thermodynamic quantities of Zr-doped γ-TiAl (Ti8Al7Zr and Ti7ZrAl8) and intrinsic γ-TiAl systems were investigated by first-principles method based on density functional theory. The calculation and analysis results about the geometrical structures and binding energies show that Zr doping γ-TiAl through substitution can improve the stability and ductility of the corresponding materials. The band structures and densities of state exhibit that both Ti8Al7Zr and Ti7ZrAl8 systems possess conductivity of metals. The obtained photon dispersions imply the good stability of Ti7ZrAl8 system. The calculation results show that the thermal capacity and conductivity of Ti8Al7Zr and Ti7ZrAl8 systems at high temperature are improved significantly, which are higher and more stable than that of γ-TiAl system. The great thermal capacity and conductivity of Ti8Al7Zr and Ti7ZrAl8 systems are propitious to the technological applications of γ-TiAl based alloys.
  • Preparation and performance of PDMS/silane modified ZSM-5 composite membranes
    Bao_li Shi
    . 2014, 45(19): 12-0.
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    Composite polydimethylsiloxane (PDMS) pervaporation membranes were prepared by incorporating surface modified ZSM-5 particles with γ-AminopropyltrIethoxysilane into the polymer matrix. The separation performances of the hybrid membranes in 10% ethanol-water system were investigated, and results show that adding the modified ZSM-5 particles could improve the separation performances of the membranes remarkably. The separation factor and total flux reached 14.1 and 348.7 g?m-2?h-1 at 40°C, respectively.
  • Research on field emission property of the planar-gate triode with double-layer films cathode treated by pulse voltage
    Jin-Yang LIN
    . 2014, 45(19): 13-0.
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    In this paper, the field emission properties of the planar-gate triode with double-layer films cathode improved by post-treatment of pulse voltage. The field emission device based on the planar-gate triode with B2O3/SnO2 double-layer films based Surface conducted Emitter (SCE) has been successfully fabricated by magnetron sputtering. The double-layer film’s surface morphology was characterized by atomic force microscopy, and its field emission (FE) properties were investigated. The experiment results show that the field emission properties such as brightness, uniformity greatly improved by post-treatment of pulse voltage. The device produced a brightness of 462 cd/m2 when the anode voltage is 3000 V and the gate voltage is 190 V. The planar-gate triode with double-layer films cathode improved by post-treatment of pulse voltage was a feasible method for improving field emission properties. The results provided an effective experimental method for improving SED structure and cathode.
  • Self-cleaning fluorocarbon aluminum with N-TiO2 film preparation process parameters optimization
    Hong Yan
    . 2014, 45(19): 14-0.
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    Visible-light-active N-TiO2 photocatalyst was synthesized by the sol-gel method with using urea and ammonia as the nitrogen precursor at low temperature, structural and photocatalyst performance of such photocatalyst were characterized by XRD, SEM, FITR and UV-Vis. The results showed when urea was used as nitrogen precursor, under the conditions of the pH of sol was 2, the molar percent of alcohol to Ti(OBu)4 was 10, water-bath temperature was 65℃, the molar percent of N/Ti was 0.06, the anatase was the mian constituent, N-TiO2 had obviously visible-light-activity, high crystallinity and the film with a uniform surface. And it was obviously higher than that of ammonia as the nitrogen precursor.
  • Relative density and proprieties of copper-graphite composites fabricated by pressure sintering processing
    YE Yu-shun ZUO Xiao-qing
    . 2014, 45(19): 15-0.
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    To improve the relative density, microstructure and properties of copper-graphite composites, an argon protective pressure sintering technology was adopted. The effects of sintering pressure, compacting pressure, sintering temperature and sintering holding time on relative density and properties, and the relationship between the relative density and properties were studied. The results showed that: An appropriate increasing with experimental parameters of the pressure sintering processing of copper-graphite composites was beneficial to decrease the number of pores, enhance uniformity of the microstructure, enhance relative density, therefore, increase hardness and conductivity. The properties were mainly determined by the relative density, the higher the relative density, the better the performance, however, they were also affected by the size and shape of the pores. The copper-graphite composites with relative density 0.945, hardness 66.3HB and conductivity 6.2MS/m were fabricated by the following optimal parameters: sintering pressure 150MPa, compacting pressure 400MPa, sintering temperature 870℃ and sintering holding time 2.5h.
  • Study on Humidity-Sensititive Properties of Multi-walled Carbon Nanotubes/ Graphene Oxide /Silicon Rubber Composite Film
    Liang PAN
    . 2014, 45(19): 16-0.
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    Abstract: A kind of o-MWCNTs/GO/RTV composite film which was sensitive to humidity was prepared by ultrasonicly mixing multi-walled carbon nanotubes (MWCNTs) which was chemically modified with graphene oxide (GO) which was prepared by Hummers method, adding room temperature vulcanized silicone rubber (RTV) in the paper. The modified multi-walled carbon nanotubes and graphene oxide were characterized by TEM and FT-IR. In addition, the sensing property to humidity and its mechanism of o-MWCNTs/GO/RTV composite film were also discussed in the paper. The results showed that the carboxyl groups and hydroxyl groups appeared on the sidewalls and at the ends of the carbon nanotubes after they were treated by mixed acid, which was benefit to the adsorption of water molecules on it, and also benefit to reaction with the function group on the surface of GO, forming three-dimensional nano-micron structure and improving the compatibility of the carbon nanotubes and silicone rubber matrix. The results presented that the humidity sensitivity of the prepared o-MWCNTs/GO/RTV composite film was increased. When the relative humidity was in the range of 23%-87%, the sensitivity of o-MWCNTs/GO/RTV humidity film was 0.0.3152/%RH, and the response time and recovery time were 4s and 27s respectively.
  • Effects of Different Cations on the Formation of Thaumasite
    . 2014, 45(19): 17-0.
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    Effects of different cations on the formation of thaumasite were studied in this paper. The cement-ground limestone paste specimens were immerged in sodium sulfate and magnesium sulfate solution with different concentrations, and the appearance of corroded pastes was observed. Besides, the corrosion products were also characterized by X-ray diffraction and infrared spectrum. The results showed that the specimens which were immerged in sodium sulfate and magnesium sulfate solution were damaged by thaumasite form of sulfate attack (TSA) badly and the damage condition became more and more serious as time evolved. The specimens immerged in sodium sulfate solution, deteriorated seriously as concentration increased and the corrosion products were mainly thaumasite. The cement-ground limestone pastes immerged in magnesium sulfate solution gradually became non-cementitious muddy material from the outside to the inside, and the corrosion products were mainly thaumasite and gypsum. Therefore, magnesium ion can accelerate thaumasite formation.
  • Study on Recovery of Metallic Sn by Electrolytic Method
    Pan-Pan CAO
    . 2014, 45(19): 18-0.
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    Al-Si-Sn ternary alloy refining method can significantly improve the purification yield of solar grade polysilicon, but the main problem of separating added metallic Sn and Si limits its practical application. The galvanostatic deposition experiment of Al-Si-Sn alloy at room temperature in SnCl2 (60 g ? L-1) electrolyte solution was studied in this research. Al-Si-Sn alloy for the anode electrode and high purity Sn (99.99%) for the cathode electrode were used. The effects of current density, electrolyte pH value, deposition time and other parameters on the current efficiency and the morphology of deposited tin were discussed to optimize the experimental process of electrolytic recovery of metal Sn. The results show that at room temperature, current efficiency reaches maximum when magnetic stirring speed is 800 r/min, current density is 0.4~0.5 A/cm2, deposition time is 3~6min, and pH value is 3~4.
  • Simulation of solidification structure of 6.5%Si steel ingot based on CAFE method
    . 2014, 45(19): 19-0.
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    The solidification structure of 6.5%Si steel ingot was simulated based on CAFE method. The simulation results, both the average grain size and proportion of columnar crystals, agree well with the experimental results. The values suitable for simulating the structure of high silicon steel wad ascertained, which are nS,max=3.5×105 m-2, nV,max=1.66×108m-3, ΔTS,n =0.5K, ΔTV,n =7.5K, ΔTS,σ=0.1K, ΔTV,σ=0.1K. The influence of superheat and cooling condition on the solidification structure are studied. It is shown that with the superheat decreasing, the proportion of columnar crystals decrease, and the average grain size become smaller. Under water cooling condition, the solidification structure of casting is composed of almost all coarse columnar grains. Under air cooling condition, equiaxed grains zone expanded, while columnar grains still account for the main part of the structure. Under slow cooling condition, equiaxed grains account for the main part of the structure and the average grain size is basically the same with those under air cooling condition.
  • Manufacturing and characterization of composite chemical plating lightweight conductive particles base on microorganisms template
    Yanyan Hu
    . 2014, 45(19): 20-0.
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    In this paper, Cu@Ag is coated on biological particles (diatomaceous earth and spirulina) by Chemical plating electroless plating to manufacture bio-based core-shell-type conductive particles. The appearance shape, surface morphology, coating composition and phase structure of Cu@Ag-coated diatomite are characterized by optical microscopy, scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. The results show that, high quality bio-type conductive particles surface can be made by adjusting the proportion of electroless copper plating solution and electroless silver plating solution. The density of bio-type conductive particles is much lower than that of the pure metal powder.
  • Research progress on preparation technology of potassium sodium niobate based lead-free piezoelectric ceramics
    sha shaFENG Fang-Xu LI
    . 2014, 45(19): 21-0.
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    Based on the requirements of protecting the environment for human beings and the development of environmentally friendly materials and devices, sodium potassium niobate (K0.5Na0.5NbO3 or KNN) lead-free piezoelectric ceramics has become one of the research hot topics worldwide at present for new piezo- and ferroelectric materials because of their excellent electrical properties and higher Curie temperatures. Materials fabrication technology plays an extremely important pole in material science and technology. In this paper, the authors review the recent research progress and development of the fabrication techniques of potassium sodium niobate based lead-free piezoelectric ceramics worldwide especially in powder preparation, ceramics sintering and ceramic texture, and their future perspectives are also given out.
  • Research on surface functionalization of different size silicon particles via wet chemistry
    . 2014, 45(19): 22-0.
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    Utilizing “wet chemistry” approaches, hydrosilylation was optimized by the etching system, the way of degassing dissolved oxygen, separation method. Silicon microparticles, silicon nanoparticles, silicon quantum dots were successfully grafted with 1-alkenes. FT-IR and SEM were shown that the functionalization of silicon particles with 1-alkenes yielded alkyl-terminated particles via Si–C bond, compared with unfunctionalized silicon particles, they were hydrophobic and had higher kinetic stability, oxidation resistance, which could form a stable dispersion in organic solvents. It was worth mentioning that, the fluorescence properties of functionalized silicon quantum dots had been greatly improved, which could be used in the field of optoelectronics.
  • Preparation and Photocatalytic Activity of Co-doped ZnGa2O4 Photocatalysts
    wenhui yuan
    . 2014, 45(19): 23-0.
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    The cubic Zn1-xCoxGa2O4 photocatalysts were synthesized by hydrothermal method using ZnCl2、Ga(NO3)3·xH2O、CoCl2·6H2O as raw material. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), UV-Vis diffusion reflectance spectra (UV-Vis) and X-ray photoelectron spectroscope (XPS). The results indicate that the Co is successfully incorporated into the ZnGa2O4 lattice, and Co doping can influence the crystalline morphology and narrow the band gap of photocatalysts. The experiments of photocatalytic degradation of RhB results demonstrate that Co doping can greatly enhance the photocatalytic activity of Zn1-xCoxGa2O4. When Co dopant is x=0.010, the photocatalytic activity reaches the maximum. Moreover, the photocatalytic degradation of RhB follows a pseudo-first-order reaction. The mechanism of enhanced photocatalytic activity is also discussed.
  • Al Substituted and Sintering Temperature of Ni-Zn Ferrites for Magnetic Properties
    Xin Huang
    . 2014, 45(19): 24-0.
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    Al substituted Ni0.5Zn0.5AlxFe2-xO4(x=0-0.10) ferrite materials were prepared by using ceramic technology, XRD、B-H analyzer and impedance analyzer were applied to investigate its structural morphological and magnetic properties. The experimental results indicate that the best sintering temperature is 1250℃ and an over-high or over-low sintering temperature is adverse to reduce the magnetic core loss. Ferrite can achieve a preferably integrated performance with x=0.06.
  • Preparation and characteristics of paraffin microcapsule applied in building energy conversation
    Shuang-Feng WANG
    . 2014, 45(19): 25-0.
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    The microcapsule for phase change material (MEPCM) was prepared by emulsion polymerization method using paraffin as core material, and methyl methacrylate, methacrylate copolymer (P( MMA-co-MA)) as shell, which was applicable to building envelope. The morphology, thermal performance, chemical structure, size distributions of MEPCM were characterized by SEM, DSC, FTIR, TGA, laser particle analyzer. The experiment was used to investigate the influence of SDS、SDBS、CTMAB、OP-10 on microcapsule morphology. The results showed that MEPCM prepared at the core-to-shell ration of 1.2 and OP-10 emusifier, had a spherical structure, and excellent thermal stability. The mean diameter, melt point, latent heats, encapsulation efficiency of MEPCM were 252.17nm, 25.12℃, 61.28 J/g and 71.29%, respectively. That is，the phase transition temperature of microcapsule was in human body comfortable zone，and the phase change enthalpy was high, so it was applicable to building energy efficiency.
  • The Influence of the Aphanitic Graphite’s Content and Diameter on the Thermal Conductivity of Composites
    . 2014, 45(19): 26-0.
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    Regarding natural aphanitic graphite and PVA as thermal conducting fillers and binder respectively, the research adopts the hot pressing method to prepare the thermal conductive composite of aphanitic graphite/PVA. Meanwhile, the influence of the content and particle of aphanitic graphite before and after purification on the composites’ thermal conductivity is studied. The indications of the results are as follows: on the one hand, along with the increase of graphite content, the thermal diffusivity of composites rises, namely when the content of aphanitic graphite is 89% and 99% respectively, the thermal diffusivity of composites is 5.224mm2/s and 7.459mm2/s respectively by the preparation of raw ore, and the thermal diffusivity of composites is 7.839mm2/sand 9.458mm2/s respectively by the preparation of aphanitic graphite after purification, which suggest that the thermal diffusivity of composites through the purification is better improved than raw ore. On the other hand, when the aphanitic graphite before and after purification without milling and the milling with the speed of 300 r/min～600 r/min, the thermal diffusivity of composites declines along with the reduce of average particle size, namely the thermal diffusivity of composites including the aphanitic graphite by the milling of raw ore and PVA drops to 4.682mm2/s from 5.224mm2/s, and the thermal diffusivity of composites covering the aphanitic graphite by the milling of purification and PVA falls to 6.019mm2/s from 7.839mm2/s. According to the above results, it is turned out that the thermal conductivity of composites from the effect of the content and particle of aphanitic graphite increases with the improvement of graphite content and decreases with the diminution of graphite content.
  • Study on Tensile Properties, Microstructure and Crystallization Behavior of Polylactide Blends
    . 2014, 45(19): 27-0.
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    Abstract ：The tensile properties, micro-structure and crystallization behavior of polylactide binary composites with butylene glycol - adipic acid - ternary terephthalate polyester (PBAT) or polybutylene succinate (PBS) and their ternary composites with further addition of rigid filler LAK (sulfate ingredient) were investigated in this work. The mechanical study indicated that the addition of PBAT or PBS resulted in great improvement of the elongation at break and enhanced the poor toughness of PLA. The addition of LAK particles into 10wt% PLA-PBS system also resulted in the improvement of its elongation at break. The morphology study of PLA tensile fracture surface by SEM indicated the dominated deformation mechanism of toughened PLA blends was attributed to the cavitation formation from the interface between PLA and the second polymer or the rigid particles. Both the addition of PBAT and PBS promoted the crystallization behavior of PLA, and the addition of PBS also resulted in the different type of PLA crystalline. LAK particles acted as nucleating agents in the PLA ternary composites and further decreased the half-crystallization time. Based on the parameters calculated by Avrami equation, the addition of LAK particles into both PLA-PBAT and PLA-PBS system have the similar crystal nucleating and growth process.
  • Effects of hot extrusion and heat treatment on mechanical properties of in-situ (Al3Zr+ZrB2)p/ 6063Al composites
    . 2014, 45(19): 28-0.
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    Aluminum matrix composites reinforced by in-situ Al3Zr and ZrB2 particles were successfully fabricated from Al-KBF4-K2ZrF6 system via Direct Melt Reaction. Extrusion processing and heat treatment were performed to find the effect of hot extrusion and a heat treatment solution for the highest figure of the tensile strength to the composite.The morphologies of the in-situ particles and mechanical properties of the composite were investigated by SEM, EDS, XRD, OM and tensile tests. The results show that both extrusion and heat treatment has a positive influence on the microstructure and tensile strength of the composite, which increases 6% and 20% respectively. And the influencing sequence of the heat treatment parameters on the tensile strength is: solution treatment temperature, aging temperature and aging time. The specimen with solution treatment for 4 h at 723K and aging temperature for 4 h at 423K reaches the highest figure of tensile strength with moderate extensibility loss.
  • High pressure high temperature synthesis of BiMnO3 and its structure and magnetic properties
    hongsheng jia
    . 2014, 45(19): 29-0.
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    The BiMnO3 sintered body with perovskite structure was prepared, using Bi2O3, MnO2 and Mn powders as starting materials (Bi2O3/MnO2/Mn =2:3:1), under high temperature and high pressure (HPHT, 3-5 GPa, 600-800 °C) conditions in a China CS-IV type cubic-anvil high pressure apparatus (CHPA). The sintered samples were tested and analyzed by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM), and the effects of sintering temperature and pressure on the sample structure, morphology and magnetic properties were studied. The experimental results show that: when the sintering temperature is 600 °C, the grains of perovskite BiMnO3 begin to form; with the increase of temperature, the relative content of BiMnO3 increases and the saturation magnetization increases gradually. While the saturation magnetization increases first and then decreases with the pressure increases; the coercivity decreases with decreasing of grain size. The optimum experimental synthesis conditions of BiMnO3 single-phase with perovskite structure are 4 GPa, 800 °C, 1 h, and its Curie temperature is 99 K. Under the test-temperature of 90 K, the maximum saturation magnetization and minimum coercivity are 35 emu/g and 37.6 Oe respectively.
  • Effect of particle size and temperature on magnetization properties of carbonyl iron powder
    Dao-Ming WANG Zu-Zhi TIAN Fei CHEN
    . 2014, 45(19): 30-0.
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    In order to reveal the influence rules of particle size and temperature on magnetization properties of carbonyl iron powder (CIP), the magnetization characteristic curves of two kinds of CIP with different particle sizes at room temperature were measured separately using a vibrating sample magnetometer. Then, the temperature effect on magnetization properties of CIP with a particle diameter of 7μm was investigated as well. Research results show that the CIP with a larger particle size exhibits more excellent magnetization performance, whose magnetization are relatively larger while the coercivity is smaller under a same magnetic field; The temperature rise will result in a increasing field intensity required for the particle to reach the same magnetization and a decrease in the corresponding magnetization, and this effect becomes more obvious as the temperature increases; After a long working period under high temperature, the particle magnetism will undergo a severe reduction due to the formation of the surface oxide layer.
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