30 January 2014, Volume 45 Issue 02
    

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    综述 进展
  • Xiu-Zhen WEI
    . 2014, 45(02): 1-0.
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    In recent years, as a new type of anti-fouling material, the zwitterion has attracted more and more attentions. Zwitterionic polymer contains both cationic and anionic groups in the polymer molecules. The anti-fouling performance of zwitterionic polymer membranes is enhanced obviously due to the strong hydration and protein adhesion resistance in aqueous solution. This article reviews several typical zwitterions for the membranes modification and the improvement of anti-fouling performance in recent years. The current research, existing problems and development trends of the membranes modification with zwitterions are also presented.
  • ; ;
    . 2014, 45(02): 2-0.
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    Carbon nanopaper is a kind of carbon-based functional material with good comprehensive performance and has a broad prospect for applications. The background and definition of carbon nanopaper was described briefly in this paper, and the classification, preparation method and application of carbon nanopaper were illustrated in detail. The advantages and disadvantages of carbon nanopaper making from different carbon nanomaterials were compared, and the prospect for the development of carbon nanopaper was given. This review will provide some theoretical basics and research directions for the further research of novel carbon nanopaper.
  • Yan LU;;;
    . 2014, 45(02): 3-0.
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    Increasing attention has been paid to polyaniline nanocomposites as potential thermoelectric material due to its lightweight, flexible, and easy to process. This article reviews the recent research progress on the conductive polyaniline nanocomposite thermoelectric materials, and mainly focuses on the effects of the intrinsic properties, dispersed states and the doping amount of adding inorganic nano-phases ( i.e. carbon nanotubes, graphene, alloy ect.) on the degree of crystallinity, orderly chain structure and thermoelectric performance of the polyaniline. The modification mechanisms of thermoelectric performance of the polyaniline nanocomposites are discussed briefly. Finally, the possible strategies to improve thermoelectric performance are proposed.
  • 工艺 技术
  • . 2014, 45(02): 4-0.
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    Ti-Mo alloy powder were fabricated for the getter matertial by metal powder injection molding technique. The effects of debinding process on sample quality, microstructure and component properties were investigated. The effects of different solvent, temperature and time in chemical debinding process on debinding rate were discussed; According to DTA/TG curves, thermal debinding technology was optimized, Debinding technology parameters of powder injection molding were confirmed, Ti-Mo getter devices made by powder injection molding technique exhibited the excellent properties.
  • 研究 开发
  • . 2014, 45(02): 5-0.
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    The microstructure and conductive characteristics of carbon black/silicone rubber conductive composites are studied. The composites based on insulating silicone rubber filled witch conductive nano carbon black particles having a conductive property. The resistivity of the composites under different carbon black content relationship is obtained and when carbon black mass fraction is greater than 4%, the electrical conductivity are better. The carbon black particles which are not uniform rules appear as two kinds of structure-“aggregate” and “chain” which connects with “aggregate” according to SEM images. The “aggregate” and “chain” are simplified to “large particles” structures which can be deformed and the carriers transfer between the “large particles” through mutual contact and the tunneling effect; assumptions, the conductive model is to establish.
  • Ming-Li XU ;;;
    . 2014, 45(02): 6-0.
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    In this paper, functionalized MWCNTs were used as a new support for Au nanoparticles synthesized by photochemical reduction. MWCNTs were modified by methylene blue under ultraviolet light (f1-MWCNTs), and then Au nanoparticles were assembled on the surface of f1-MWCNTs. Fourier transform infrared (FT-IR) absorption spectroscopy revealed that C-N group and N-H group existed in the surface of f1-MWCNTs. These groups might be active sites for Au nanoparticles loaded on the f1-MWCNTs. The morphology and structure of catalysts were characterized by transmission electron microscopy (TEM) and X-ray diffraction spectrum (XRD). The consequences showed that Au nanoparticles with face-centered cubic crystal structure were about 4.5 nm in size, and were uniformly dispersed on the surface of f1-MWCNTs. Electrochemical experiments indicated that the Au/f1-MWCNTs catalyst exhibited excellent catalytic performance for methanol oxidation in alkaline solution, and the mass specific current density of the peak for Pd/f1-MWCNTs was 1.56 times higher than that for Au/f0-MWCNTs, which were functionalized by methylene blue without ultraviolet irradition.
  • ;; ;
    . 2014, 45(02): 7-0.
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    Hydroxyapatite nanoparticles were synthesized via a W/O process with Ca(NO3)2·4H2O and H3PO4 as raw material.PAM-HA particles were obtained by PAM modification HA in water solution. The morphology, size,phase structure and FT-IR spectrum of HA and PAM-HA were characterized by transmission electron microscopy, X-ray diffraction, FT-IR spectrograph. The experimental results showed that PAM played a role in crystal transformed of HA, CaHPO4 crystalline phase appeared.The size of PAM modified rod-shaped HA particles were from 80 nm to 120 nm. Characteristic peak in the 1635.6 cm - 1 showed that PAM and Ca2 + in the HA complexation, PAM grafted on the surface of HA. In addition, the dispersion and adsorption performance (Cu2 +) of PAM-HA were improved.
  • Yang YANGGuoqiu He
    . 2014, 45(02): 9-0.
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    The fretting fatigue behavior of 35CrMoA and its microstructure were investigated by the means of plane to plane contact. Dislocation structure at the contact area was observed by transmission electron microscopy (TEM), and analyzed at different contact stress and different cycles during the process of fretting fatigue. The results indicate that the fretting fatigue life of 35CrMoA decreases with the contact stress increasing. However, the fatigue life reduction trend is different at the different contact stress range; With the increase of fretting fatigue cycle, the density of dislocation increases gradually and dislocations are intertwined mutually, further form the dislocation cell; Dislocation cells are all formed in the late of fretting fatigue at different contact stress; Stacking fault substructure is also found in the surface layer of fretting fatigue, and persistent slip band is easy to form in the surface layer of the fretting fatigue contact area.
  • 工艺 技术
  • Xin-Ming ZHANG;Zhen-Xing LIUJian-Guo TANG
    . 2014, 45(02): 10-0.
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    The influences of precipitates on relative resistivity of 6101 aluminium alloy in aging at 175 ℃-195 ℃ was investigated by hardness-testing, in-situ resistivity testing and transmission electron microscopy(TEM), and the modified Matthiessen’ low was introduced to calculate the influence on resistivity at different aging time. Results about the aging temperature and time were gotten. It suggested that the shorter the forming time of clusters at the early stage of aging is, the lower the relative resistivity and the hardness is. At the later stage of aging at 175 ℃, the increasing of the density of precipitates leads to the decrease of the spacing ,and the relative resistivity almost retains. From this research the aging treatment 175 ℃/680 min emphasizing on high strength and 195℃/220 min emphasizing on good conductivity were constituted and ensured reasonably by performance.
  • ; Bao-hong TIANYi Zhang
    . 2014, 45(02): 11-0.
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    Using VDBF-250 vacuum hot pressing sintering furnace 10vol%TiC/Cu-Al2O3 composite was prepared by vacuum-pressed sintering. Using the Gleeble-1500D simulator, the high-temperature plastic deformation behavior and processing map of 10vol%TiC/Cu-Al2O3 composite was investigated at 450?850℃ with the strain rate of 0.001?1s?1 and total strain of 0.7 The results show that the density, microhardness and electrical conductivity of the composite are 98.53%, 158HV and 48.7%IACS. The softening mechanism of the dynamic recrystallization is a feature of high-temperature flow stress?strain curves of the composites, and the peak stress increases with the decrease of deformation temperature or the increase of strain rate, and Belong to temperature and strain rate sensitive material. Meanwhile, the obtained processing map of dynamic material modeling is used to analyze the deformation mechanism and the destabilization mechanism of 10vol%TiC/Cu-Al2O3 composite, the optimal deformation processing parameters of the deformation temperatures range and the strain rates range are 750?850℃ and 0.01?0.1s?1.
  • . 2014, 45(02): 12-0.
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    Bentonite/sodium lignosulfonate graft acrylamide and maleic anhydride adsorbent composites (BLAMA) was prepared by solution polymerization using sodium lignosulfonate (LS-Na), acrylamide (AM) and maleic anhydride (MAH) as raw materials, bentonite as inorganic filler, potassium peroxydisulfate (KPS) as initiator, N, N-methylene-bis-acrylamide (NMBA) as crosslinker.Based on the assessment of the adsorption capacity of Pb2+ and the selectivity of Pb2+ to Cu2+ in the Pb2+/Cu2+ binary metal ion solution, the preferable formula was obtained as follow: m(LS-Na): m(Mtotal)=1:7, m(AM): m(MAH)=1:1, m(KPS)= 0.7﹪, m(NMBA)= 0.3﹪(the mass of KPS and NMBA was both based on total mass of monomer, Mtotal), pH=4. And in this condition, BLAMA had a higher adsorption capacity and its maximum value of Pb2+ was 0.471mmol/g, and the adsorption selectivity of Pb2+ to Cu2+ was 3.6:1(mole ratio) in the Pb2+/Cu2+ binary metal ion solution.
  • ZHU Shao Feng
    . 2014, 45(02): 13-0.
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    In this paper,foam glass as thermal insulation material was prepared from alkali-free glass powder by powder-sintering method, the SiC as foaming agent within the process. The influences of sintering temperature and holding time on pore structure, apparent density,porosity and compression strength were studied by scanning electron microscope and x-ray diffraction. The results show that, with upgrading the sintering temperature and holding time, apparent density of foam glass declined, average pore size gradually increasing and at the same time connecting pore appear. Under the conditions of sintering temperature of 940℃ and holding time of 30 min, the product is with apparent density 0.46g/cm3, compression strength 3.81MPa, water absorption 0.41% and the pores of the bubble size of 1 ~ 3mm more than 80%.
  • Chen-guang HU ;;
    . 2014, 45(02): 14-0.
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    Based on the temperature variation in the interior of mass concrete, the effect of sulfate ions on distribution of Al3+ coordination in hardened cement pastes at variable temperature were investigated by 27Al Magic Angle Spinning (MAS) Nuclear Magnetic Resonance(NMR) with deconvolution technique. The results indicate that the high temperature during the variable temperature process promotes ettringite (AFt), Third Aluminum Hydrate (TAH) and tetrahedral coordination Al3+ (Al[4]) incorporated in C-S-H structure transforming to monosulphate (AFm). And the decreasing temperature process promotes the formation of TAH, and is beneficial to the AFm and Al[4] transforming to the AFt. But the normal temperature of 20℃ is not only advantageous for transformation from AFt to AFm, from TAH to Al[4], but also for Al[4] entering into the C-S-H structure with high Ca/Si. However, in 5% Na2SO4 solution, firstly, the AFt is formed due to AFm attacked by the sulfate ions, and the effect of sulfate ions on the TAH and tetrahedral coordination Al3+ in C-S-H structure is less at 3d. The variation temperature speeds up the corrosion of sulfate ions for TAH and Al[4], and there is a dealuminization of the sulfate ions for C-S-A-H gels. Moreover, the normal temperature of 20℃ is beneficial to competition of C-S-H gels with sulfate ions for the Al[4], and the sulfate ions resistance of dealuminization of C-S-A-H gels with low Ca/Si is stronger.
  • 研究 开发
  • . 2014, 45(02): 15-0.
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    In order to study the impacts of the surface pattern on its wettability and antifouling performance, laser etching technique was used to build dot and grid similarly to the surface morphology of shell micro-structure with different spacing. Nano-SiO2 powders were coated on the micro-structure to build micro-nano structure. The results show that after laser etching, Ti6Al4V alloy surface state change from hydrophilic to super hydrophilic. After low surface energy modification, the dot micro structure surface is hydrophobic state in accordance with Wenzel model, but the grid micro structure surface is super hydrophobic state in accordance with Cassie model. The surface with the micro-nano structure formed by coating the Nano-SiO2 on the dot and grid micro-structure are all super hydrophobic state in accordance with Cassie model. The grid structure surfaces have greater?contact angles and smaller roll angles.? Sea-site exposure test show that the microbial membrane attachment for several surfaces are in the order from large to small ,the dot micro-structure surface with super hydrophilic state, polishing surface with hydrophilic state, grid micro-structure surface with super hydrophilic state, the super hydrophobic surface in accordance with Cassie model.
  • ;Zhi-Gang GAI
    . 2014, 45(02): 16-0.
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    In this paper,high temperature bismuth layer-structured piezoelectric ceramics [(NaBi)1-x(LiCe)x]0.5Bi2Nb2O9(x=0.00, 0.04, 0.06, 0.08) was prepared by the solid-state reaction,and the effect of (LiCe) doping on the properties of Na0.5Bi2.5Nb2O9-based ceramics was investigated. The (LiCe) modification accelerates the growth of grains, and causes the lattice distortion which greatly improves the piezoelectric activity of the samples. the temperature stability of the piezoelectric and dielectric properties of Na0.5Bi2.5Nb2O9-based ceramics was also improved by the (LiCe) modification. The d33 of x=0.06 was found to be 24 pC/N, the highest value among the Na0.5Bi2.5Nb2O9-based ceramics and more than 2 times as much as the d33 values of the pure Na0.5Bi2.5Nb2O9 ceramics . The planar coupling factor kp, thickness coupling factor kt of Na0.5Bi2.5Nb2O9 ceramic were found to be 12%, 25%, respectively, together with the high TC ,low dielectric loss(only 0.26% at 1KHz) and stable piezoelectric properties, demonstrating that the (LiCe) modified Na0.5Bi2.5Nb2O9-based material a wonderful candidate for high temperature applications.
  • ;;
    . 2014, 45(02): 18-0.
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    Hexagonal mesoporous silica (HMS) and Titanium-containing hexagonal mesoporous silica (Ti-HMS) with different Ti contents were synthesized by using neutral dodecylamine as template and tetraethyl orthosilicate as Si source in neutral solution and at ambient temperature. HMS and Ti-HMS as supports of Cu-HMS and Cu/Ti-HMS, the samples were obtained by impregnation method, respectively. The obtained samples were characterized by X-ray powder diffraction (XRD), pyridine adsorption in Fourier transform infrared (FT-IR) spectroscopy and scanning electron microscopy (SEM). The effects of the mole ratio of n(Si)/n(Ti), the reaction time, the amount of the Cu/Ti-HMS catalyst, the reaction temperature, and the mole ratio of H2O2/S on the removal rate were studied. The results showed that HMS and Ti-HMS have the typical hexagonal mesoporous structure and the structure was kepted well after the copper was incoporated. Cu/Ti-HMS showed high activity in removing thiophene in model oil. The desulfurization rate reached up to 93.54% with a H2O2/S mole ratio of 4:1 at atmospheric pressure and 333 K, using acetonitrile as the extractant.
  • Lei LUO;Hui QIAO ;Qu-Fu WEI
    . 2014, 45(02): 19-0.
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    The PVP/TNBT composite nanofibers consisting of Polyvinyl pyrrolidone (PVP), tetrabutyl titanate(TNBT) and acetone as solvent were successfully fabricated by the technique of electrospunning, then porous titanium dioxide nanofibers were prepared by annealing PVP/TBT composite nanofibers which obtained by electrospinning. The structure and morphology of the obtained materials were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), thermogravimetry (TG) ,differential scanning calorimetry (DSC) and specific surface area (BET). The photocatalytic activity of porous TiO2 nanofibers were studied under the condition that simulated ultraviolet irradiation was used as irraditon light source, and methylene blue was used as target pollutant. The results show that porous TiO2 nanofibers which obtained under 700 ℃ calcinated have the best photocatalytic activity, 95.2% of degradation efficiency was achieved after 3 hours irradiation.
  • ;;;;
    . 2014, 45(02): 20-0.
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    As-cast microstructure and grain refinement in the AZ91 magnesium alloys with different Sr contents (0, 0.05, 0.1, 0.3, and 0.6 wt.%) were observed in this paper, and the grain refining mechanism was analyzed by using the calculation of "edge-to-edge" matching model. The results indicated that adding trace Sr to as-cast AZ91 alloy had obviously effects on grain refinement, thereinto with the addition of 0.05% Sr is the most remarkable. In addition, the [0 2 1]Al4Sr∥[1 -1 0]Mg17Al12 and (2 0 0)Al4Sr∥(3 3 2)Mg17Al12 were calculated by using "edge-to-edge" matching model, which can provide an evidence that the Al4Sr phase is the effective heterogeneous nucleant for the Mg17Al12 phase probably. However, the mechanism of grain refinement of trace Sr effect on the as-cast microstructure of AZ91 magnesium alloy is the Al4Sr phase provide heterogeneous nucleant for the Mg17Al12 phase that accelerating the formation of Mg17Al12 phase and then restricted the growth of α-Mg.
  • ;Xue Ji-wu ;;;
    . 2014, 45(02): 21-0.
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    Using 3-Mercaptopropionic acid(MPA) as surface coated agent,Mn2+-doped water- soluble quantum dots of ZnS were synthesized by co-precipitation method.The effects of Mn2+ dopant and doping amount on microstructure, morphology and photoluminescence properties of the As-products were researched by X-ray diffraction, transmission electron microscopy, UV-visible absorption spectrometer,and fluorescence spectrophotometer.The results show that the products were irregular spherical cubic zinc blender ZnS with sizes around 9.7nm. Photoluminescence spectra analysis show that Mn2+-doped ZnS quantum dots appeared two emission peaks located at 587nm and 637nm which indicated ZnS surface emitting and Mn2+: 4T1-?6A1 level characteristic luminescence respectively.The synthesis mechanism of Mn2+-doped ZnS quantum dots was studied by infrared spectroscopy.
  • ;
    . 2014, 45(02): 22-0.
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    A series of solvent-free anion polyurethane/acrylate (WPUA) dispersions modified with epoxy resin (E-44) were successfully synthesized by in-situ emulsion polymerization. Effects of E-44 content on appearance, centrifugal stability of the dispersions were studied, as well as thermal properties, water and alcohol resistance, pencil hardness, adhesion and impact strength of the films. FT- IR demonstrated the hydroxyl and epoxy groups were reacted with isocyanate groups. TGA results indicated WPUA with the incorporation of E-44 had relatively higher thermostability. Additionally, the best properties of WPUA films was obtained at 7.6% E-44 content, while the water and alcohol resistance were 6.13% and 49.78%, respectively. The pencil hardness of film was 2H, the adhesion reached 0 grade, and the impact strength met requirements.
  • Xiang WAN;
    . 2014, 45(02): 23-0.
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    One-dimensional GaN nanowires were synthesized via Chemical-Vapor-deposition method with Ni and Au as catalysts by ammoniating metal Ga.SEM,TEM and XRD were used to characterize the morphology ,the microstructure of the GaN nanowires samples.By changing the key factors such as the growth temperature and time,the different kinds of catalysts,the distance between the Ga and wafers,different morphology and structures of GaN nanowires were analyzed.It was demonstrated that the VLS mode and VS mode were coexisted in our GaN nanowires growth process.Finally,the optimum growth conditions for GaN nanowires were obtained.
  • Ai-Xue DONG; ;;
    . 2014, 45(02): 24-0.
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    Grafting of lysozyme catalyzed by laccase on bast fabrics was studied. The antibacterial properties of fabrics were obtained. The graft of lysozyme was proved by method of dyeing with coomassie brilliant blue. The grafting effects of two kinds of fabrics with different lignin content (cotton/flax fabric and jute fabric) were compared. Scanning electron microscopy (SEM) presented the surface morphologies of grafted bast fibers. The washing stability and the antibacterial property of lysozyme immobilized bast fabrics were determined. The results showed that lysozyme can be immobilized on bast fabrics via the catalysis of laccase and the grafting level was gradually increasing with the increase in lignin content of bast fabrics. The antibacterial ratios of cotton/flax fabric and jute fabric could reach 60.38% and 72.87% respectively. The fabrics lysozyme immobilized by grafting would obtain better washing stability and antibacterial property than that immobilized only by adsorption.
  • . 2014, 45(02): 25-0.
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    Investigation of the surface hydrophilic/hydrophobic properties and degradation properties is to evaluate material can be applied to biomedical field . PAPI - PDLLA surface hydrophilic/hydrophobic is evaluated by the material surface static water contact Angle and water absorption comprehensive. PAPI – PDLLA degradation property is characterized by determination of weight-loss ratio, molecular weight, pH, surface morphology. Experimental results show that,the degradation of PDLLA performance by adjusting the hydrophilic block PAPI accounted for the proportion in the material, and adjusting the hydrophilic/hydrophobic properties, and it also can ease the PDLLA appeared in the process of degradation of acid accumulation problem. Therefore, PAPI-PDLLA will be applied in the field of biomedical.
  • Yan WANG
    . 2014, 45(02): 26-0.
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    The Fe3O4-carboxymethyl cellulose-polyethyleneimine (Fe3O4-CMC-PEI) microspheres were prepared by electrostatic self assembly and cross-linking in this work. First,the Fe3O4-CMC particles were prepared through assembling CMC to the surface of Fe3O4 by electrostatic interaction. Second, Fe3O4-CMC and PEI were cross-linked by glutaraldehyde to obtain the Fe3O4-CMC-PEI microspheres. The obtained microspheres were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometer (VSM). The ability of Cd (Ⅱ) ion adsorption of the Fe3O4-CMC-PEI microspheres for removal from aqueous solutions was measured with atomic absorption spectrophotometer. It was found that CMC were successfully assembled on the surface of Fe3O4 particles and Fe3O4-CMC and PEI were cross-linked by glutaraldehyde. The size of the Fe3O4-CMC-PEI microspheres ranged from 10 to 30 nm and the saturation magnetization was 55.20 emu/g. The Fe3O4 particles in the microspheres still maintained an inverse spinel structure. The Fe3O4-CMC-PEI microspheres showed their potential for the separation of Cd (Ⅱ) ion. The adsorption data obeyed the Langmuir equation with a maximum adsorption capacity of 69.44 mg/g and the adsorption kinetics followed the mechanism of the pseudo-second-order equation.
  • Hai-Quan FENG ; ;
    . 2014, 45(02): 27-0.
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    The dynamic-static coupling expansion process and biomechanical properties for three kinds of stainless steel (SUS-316L) coronary stents were investigated using nonlinear finite element method. The key technologies such as meshing, material constitutive model, boundary conditions, loading definition and contact interaction, were discussed in detail, as the stent underwent the crimp induced-contraction, free expansion, unloading and continuous pulsation circulating stresses. According to finite element analysis (FEA) results, during the coupling expansion of stents, the maximum equivalent stress was 807.9 MPa, and the maximum plastic strain was 0.208; the axial shortening rate, radial bounce rate and expanding nonuniformity of three stents were all within 13%, while the static safety factor was over 1.3, and the dynamic safety factor was over 1.1. The numerical results agreed well with experimental data and the error was less than 7%, strongly demonstrating the rationality and validity of FEA results. The proposed simulation method provides a scientific basis for the optimization and clinical evaluation of the coronary stents.
  • ; ;;;
    . 2014, 45(02): 28-0.
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    (1-x)(0.8Na0.5Bi0.5TiO3-0.2K0.5Bi0.5TiO3)-xLi0.5Bi0.5TiO3(NBT-KBT-xLBT) lead-free piezoelectric ceramics were prepared by the conventional ceramic preparation method. Crystal structure, dielectric, ferroelectric and piezoelectric properties of the ceramics were investigated. According to XRD patterns, the morphotropic boundary lies in the composition range of 0.08≤x≤0.10. The temperature dielectric anomalous peak Tf which is corresponding to the depolarization temperature towards to higher temperature while the ferroelectric-paraelectric phase transition peak Tm shift towards to lower temperature. Relaxor phase transition characteristics become stronger. The relationship between relaxation phase transition characteristics and A-site local structure are further discussed based on inhomogeneous distribution and disorder range in atomic scale. The ferroelectric properties of the NBT–KBT ceramics are further improved with the introduction of the LBT content. And the coercive field Ec decreases from 14.5 kV/cm (x=0.06) to 12.3 kV/cm (x=0.12). The piezoelectric activity is enhanced with an increase in LBT content and piezoelectric constant d33 reaches 145 pC/N at the morphotropic phase boundary(x=0.10). The lower sintering temperature, higher d33 and lower Ec value for NBT-KBT system could be obtained by the LBT incorporation.
  • 工艺 技术
  • jun Yan
    . 2014, 45(02): 29-0.
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    Short glass fiber powders were firstly treated by phytic acid, and then coated by nano TiO2 in alcohol solution of Ti(OBu)4 through peptization-hydrolyzation method. SEM observation showed that it was difficult to directly coat glass fiber with TiO2 particles without phytic acid treatment, but after treated by phytic acid nano TiO2 particles approximate 50nm in size were uniformly coated the surface of glass fiber forming porous film. The results of XPS showed that Ti elements on the surface of the composites were in the state of Ti4+ of TiO2, and there also existed Ti–O–Si bonds. XRD analysis revealed that nano TiO2 mainly existed as anatase form. Thermal analysis showed that the weight loss of the composite powders is about 6.3% during the heating process, and no obvious endothermic peak appeared in the DTA curve. Comparison of the dispersion state of the original glass fiber and the composite powders in epoxy resin was carried out by means of SEM, and the results showed that it was difficult to form effective bonding interface between the untreated glass fiber and epoxy resin, however, nano-TiO2/glass fiber composite powders were closely bonded with the resin, and it was thought that there was action of nano-TiO2in the curing process of epoxy resin, which helped to improve the interaction between the two phases.
  • . 2014, 45(02): 30-0.
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    The eutectic growth process of SCN-Cam (Succinonitrile-wt%camphor, wt% is as mass fraction) model alloy is studied with real-time observation devices and directional solidification system. It is indicated that the rod-like eutectic phase spacings of the SCN-23.6%Cam eutectic model alloy decrease with the increase of interface moving rates which is coincided with J-H model′s; With the increase of sample cell thicknesses, rod-like eutectic phase spacings of SCN-23.6%Cam model alloy increase; Under the ultrasonic vibration condition, the eutectic composition point of the SCN-Cam model alloy phase diagram moves to SCN direction, the ranges of phase and phase decrease, and the eutectic temperature increases.
  • ; ;
    . 2014, 45(02): 31-0.
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    AlN ceramics were prepared by hot-press sintering with Y2O3 as additive. The temperature dependence of the thermal conductivity of AlN ceramics was measured using the flash-diffusivity technique. Thermal conductivity data from room temperature to 200℃ was found to decrease as the temperature increasing. Stomata inhibits the rate of thermal conductivity as temperature changing. The lower porosity(the higher densification), the thermal conductivity is more sensitive to the temperature; Yttrium aluminates as grain boundary phase promotes the rate of thermal conductivity as temperature changing. The more content of yttrium aluminates, the thermal conductivity is more sensitive to the temperature.