30 April 2015, Volume 46 Issue 08

    

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研究 开发
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  Research on Fracture Toughness of Radiation-Shielding Gd3+-containing Organic Glass

  Zi-Hai LIU

  . 2015, 46(08): 1-0.

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  The plane-strain fracture toughness KIC of Gd3+-containing organic glass was investigated from the compact tension test, and the fractographs of compact tension specimen on the fracture surfaces was analysed. The fracture process under tensile stress of Gd3+-containing organic glass has been examined via in situ environmental scanning electron microscopy (ESEM). We are convinced that crack-craze model on crack tip for slow crack growth and secondary fracture model for fast crack growth of Gd3+-containing organic glass may be used to explain all phenomenons which were observed in this experiments.
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  The preparation and magnetic characterization of CoFe2O4@FeCo core-shell nanoparticles

  ;jing An Ze-Ming YUAN;

  . 2015, 46(08): 2-0.

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  CoFe2O4 nanoparticles were synthesized by the co-precipitation method and core-shell nanoparticles of CoFe2O4@FeCo were obtained by reducing CoFe2O4 nanoparticles under hydrogen atmosphere. The structure and morphology of CoFe2O4@FeCo nanoparticles were characterized by X-ray diffraction and transmission electron microscopy. The room temperature magnetization was analyzed by SQUID.We found that with the increase of shell thickness, the coercivity of core-shell nanoparticles show a trend of decrease after the first increase, and the saturation magnetization keep increasing. In order to explore the exchange interaction of core-shell nanoparticles, we also measured the M-T curves and magnetic hysteresis loops at T=5K under zero field cooling(ZFC) and field cooling(FC).
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  Electronic structures and optical absorption of Cu/Mg doped AlN

  . 2015, 46(08): 3-0.

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  The geometrical structures of AlN, AlN:Cu, AlN:Mg, and AlN:Cu-Mg 32-atom super-cell was optimized by using the first principle density functional theory based on the full potential linearized augumented plane wave method and generalized gradient approximation. Electronic structure, energy band, density of states, optical properties and magnetic moments were calculated and discussed in detail. The results show that the AlN: Cu, AlN: Mg both were 100% spin injection and have half metal material properties. The Cu doped system has more stable half metal properties. AlN: Cu - Mg system produce the spin polarization impurity band in the deep energy gap, with gold attributes, improving the electrical conductivity of the system. The system of Cu doped AlN have maximum of magnetic and the system of Cu-Mg co-doped have minimum of magenetic. It is found that systerm of the introduction of impurity ions appear obvious peak value in the complex refractive index and dielectric function function in low-energy by further analysis of the optical properties, witch strengthen the absorption of low frequency electromagnetic wave.
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  Preparation and properties of high performance Pt/TiO2 visible light catalytic materials

  Xiu-Ling ZHANG

  . 2015, 46(08): 4-0.

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  The Effects of Cu-doping on the Crystal Structure and Physical Character of ZnO Nano- film

  Qian GAO

  . 2015, 46(08): 5-0.

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  Cu-doping ZnO nano- films were prepared by a Sol-Gel technique. The crystal structures, surface morphology, transmittance, band gap and room magnetism were characterized and analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM)，atomic force microscope （AFM）,ultraviolet visible spectroscopy (UV-VLS), and vibrating sample magnetometer (VSM). The results show that the films exhibit a hexagonal structure, showing a preferential growth along c axis. Any amorphous material or secondary phase is not inspected in all synthesized samples. It indicate that Zn2+is substituted by Cu2+ in the crystal film. The roughness, the grain size, the transmittance, band gap and room magnetism of the films are improved by the changes of Cu consistence and sintering temperature. The sample of 2% Cu-doping sintered at 500oC has the least roughness and grain sizes, and has the most transmittance and room temperature ferromagnetism. But the band gap decreases with the increase of Cu consistence and sintering temperature.
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  Effects of Sputtering Power on Al Doped ZnO Thin Films Deposited by RF Magnetron Sputtering

  ;Yu -Ying ZHENG

  . 2015, 46(08): 6-0.

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  ZnO:Al (ZAO) transparent conductive thin films were sputtered on glass substrates by RF magnetron sputtering with ZnO ceramic target mixed with Al2O3 of 2% wt. The influence of sputtering power on the structural, optical and electrical performance of ZAO films were characterized by X-ray diffraction (XRD), Atomic force microscope (AFM), UV-Vis spectrograph and Van der Pauw method. The results indicate that the different sputtering power has little influence on the light transmittance, but there are greater effects on film crystallization and electrical properties. c-axis orientation of ZAO films in (002) direction is distinctly observed by XRD. The average visible (~ 400nm-600nm) transmittance is more than 85%. The optimum electrical property of ZAO film is prepared at sputtering power of 120 W.
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  Synthesis and investigation on stability of ALN/EG nanofluids

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  . 2015, 46(08): 7-0.

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  AlN/EG nanofluid was synthesized by a two-step method. The influencing factors such as time of ultrasonic agitation, pH value and dispersant on stability were investigated. The experimental results indicated that the optimal ultrasonic agitation time is 30min. The addition of acid or alkali will damage the stability of the AlN/EG nanofluids. Proper quantities of PVP can improve the stability of the AlN/EG nanofluids.
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  Synthesis and properties of the ceramic precursor containing zirconium and alkyne.

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  . 2015, 46(08): 8-0.

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  A new kind of polymeric zirconium as a Zr-based ceramic precursor has been synthesized by trichloroethylene, phenylacetylene, n-butyllithium and ZrCl4.The structure of the polymer containing zirconium and alkyne(PZA) was characterized by molecular weight, FTIR . The heat-resistant property under nitrogen was studied by TGA and the ceramic transformation was studied by XRD. Results show that PZA polymer have great heat-resistant property, the Td10(10 % mass loss temperature) was up to 600 ℃, the mass retention was 61.9% after 1000 ℃, the ceramic conversion was ZrC after 1450℃
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  Growth Mechanism of MoO2 Nanorods by Hydrothermal Process

  . 2015, 46(08): 9-0.

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  Molybdenum dioxide nanorods were prepared from peroxomolybdic acid sols via hydrothermal method. The morphology and structure of the samples were characterized by XRD, SEM and HRTEM. The growth mechanism of the MoO2 nanorods was investigated by studying the influence of hydrothermal time on the structure and morphology of the products. MoO2 nanorods were obtained by one-pot hydrothermal process using ethanol as a weak reducing agent, and the phase evolution of MoO3 nanobelts—Mo8O23 nanosheets—MoO2 nanorods was demonstrated by theoretical?and?experimental?analysis.
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  Properties of Pd doped nano ZnO prepared via a solution combustion synthesis

  LV tan;;

  . 2015, 46(08): 10-0.

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  Abstract： Pd doped nano-ZnO were prepared by solution combustion synthesis (SCS), using tartaric acid as fuel and zinc nitrate as oxidant. The samples were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and fluorescence spectroscopy, and the influence of Pd-doping on the gas sensing properties of ZnO was mainly discussed. The results indicate that at 330 ℃, the gas sensitivity of 0% and 7at% Pd-doped sensors to 50 ppm ethanol gas were 21.4 and 11.2, to 50 ppm acetone gas were 2.0 and 8.8, respectively. The selectivity of sensors to ethanol and acetone was significantly improved via Pd-doping.
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  Synthesis and Property Study on Negative Thermal Expansion ZrW2O8 Powders using the Citric acid Sol-Gel Method

  Xiu-Juan SUN ;

  . 2015, 46(08): 11-0.

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  Negative thermal expansion (NTE) material ZrW2O8 powders were synthesized by the sol-gel method with citric acid used as chelating agent.The precursor of ZrW2O8 was studied by Thermogravimetric and differential scanning calorimetry (TG-DSC). The structure and morphology of the resulting powders were characterized by Powder X-ray diffraction (XRD) and Scanning electron microscopy (SEM) respectively. The results showed that the samples were single phase of α-ZrW2O8 with irregular shape. With the increasing amount of citric acid, the particles grew bigger with a slice layer shape. The High temperature X-ray diffraction measurement indicated that the material had strong NTE. From room temperature to 500℃, the average thermal expansion coefficient was -6.14×10-6℃-1.
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  Investigation of friction behavior and wear mechanism of high-silicon content Al-Si alloy

  . 2015, 46(08): 12-0.

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  The high-silicon content Al-22Si and Al-27Si (mass fraction) alloys were prepared by spray forming and hot extrusion technique. The friction behavior and wear mechanism of Al-22Si and Al-27Si alloys under different loads at drying friction condition was investigation. The results show that, compared with the as-cast alloy, the high-silicon content Al-Si alloys prepared by spray-forming process has the characteristics of the grain fine, uniform composition. At loads of 30, 45, 60, and 75 N, the wear mechanism of Al-22Si alloy is adhesive and oxidation wear, and it is mainly adhesion wear for Al-27Si alloy at low load. However, the wear mechanism of Al-27Si alloy at high load is the mixture of adhesive wear and abrasive wear. The wear rates of both alloys increase with increasing of load gradually.
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  The preparation of carbon-based solid acid catalyst and catalytic esterification performance study

  . 2015, 46(08): 13-0.

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  A new carbon-based solid acid catalyst was prepared by a one-step carbonization method with p-toluene sulfonic acid and glucose as raw materials. The catalyst was characterized by TEM, BET, XRD, IR, elemental analysis, thermogravimetric. The double esterification reactionⅡ of the surfactant 1, 4 - butanediol dual succinate polyether (3) n-ocytl mixed double ester sulfonic acid sodium was taken as the probe reaction to investigate the impact of the m (p-toluene sulfonic acid) / m (glucose), carbonization temperature and carbonization time on the catalytic activity. The results showed that the carbon-based solid acid catalyst prepared under the optimal conditions of carbonization at 210 oC for 8 h and in the m (p-toluene sulfonic acid) / m (sugar) = 1︰2, which had a condensed ring carbon frame structure containing multiple channels and the sulfonic acid group content reached 21.21%. Esterification rate reached over 95%, and the catalyst showed considerable heat stability and reusability.
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  Investigation on the formation of nanoporous layers on TiNb alloys by ultrafast anodization

  Hu FeiZHAO CHONG

  . 2015, 46(08): 14-0.

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  Self-organized, through-hole, and ordered nano-porous array layers are fabricated by anodizing Ti-xNb(x=30~70%) alloys in a nitric acid electrolyte rapidly and directly. The nanoporous layers are characterized by XRD, SEM and TEM. It is found that TiNb oxide nanoporous layers consist of straight and uniform pores of 10-30 nm in diameter, and the back side has uniform pores of 20-60 nm. The pore spacing increases with increasing Nb and nitric acid concentration. The growth rate of the oxidation layers is more than 30 μm/h. The formation of the layers is believed to be related to the strong oxidizability of nitric acid. And the penetration of the oxidation layers might be attributed to the interactions between the compressive stress by the layers and the tensile stress generated by the polarization, concentration and temperature gradient.
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  Study on Preparation and Properties of Phosphorus Hybrid Intrinsic Flame Retardant Thermoplastic Polyurethane Elastomer

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  . 2015, 46(08): 15-0.

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  DOPOMA was synthesized by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide(DOPO) and 　maleic anhydride(MA), then it with dicarboxylic acids and diols by polycondensation reaction to get the side chain phosphorus hydroxyl-terminated saturated polyester, then it with TDI to synthesis phosphorus flame retardant thermoplastic polyurethane elastomer. Chemical composition, thermal stability, charring performance, morphology and mechanical properties of phosphorus-containing polymer were investigated by Infrared analysis(FT-IR), Thermogravimetric analysis(TGA), Limiting oxygen index (LOI), Scanning electron microscope (SEM), universal?tensiletest?machine. The results shows that the LOI gradually rising, decomposition temperature and char yield gradually increasing with the increase of P content. The polyurethane become charred layers like a compact network?after combustion, the introduction of the P element hardly influence?on the mechanical property of materials.
工艺 技术
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  Investigation on Magnetic Phase Transition for Mn1.15Fe0.85P0.55Si0.45 Compound Prepared By Copper Mould Casting

  Zhong-Ren ZHU

  . 2015, 46(08): 16-0.

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  Mn1.15Fe0.85P0.55Si0.45 ingots were prepared by arc melting and copper mould casting technique. The microstructure and magnetocaloric effects were investigated by X-ray diffraction, scanning electron microscope and physical property measurement system. The results show that Mn1.15Fe0.85P0.55Si0.45 compound crystallizes into the hexagonal Mn5.64P3-type structure with small amount of Mn3Fe2Si3 impurity phases. The Curie temperature and thermal hysteresis are about 305 K and 13.5 K respectively. The maximal magnetic entropy change of 12.2 J/(kg·K) in a field change of 2 T is obtained, which is much larger than that of pure Gd. To analyze the nature of the magnetic phase transition in detail, we have carried out the study of the critical behavior near the Curie temperature for the compound by Landau theory and universal curves theory. The Arrott plots prove that the compound undergo a first-order magnetic transition, however universal curves theory indicate that the magnetic transition is between first-order and second-order.
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  Effect of anodizing process on the dynamic wetting behavior of aluminum-epoxy

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  . 2015, 46(08): 17-0.

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  Abstract: Phosphorylated anodized surface treatment was used on aluminum alloy plate. The surface morphology of aluminum alloy was observed by electron microscopy, and the dynamic contact angle of aluminum–epoxy was measured by weighing method. Thus, the work analyzed the effect of voltage and time on the dynamic wetting behavior of aluminum-epoxy and the infiltration rate on the wetting behavior of aluminum-epoxy. Results reveal that keeping the oxidation voltage being 20V while extending the oxidative time, the dynamic contact angle decreases sharply, and then increases slowly; keeping oxidation time being 20min while increasing the oxidative voltage, the dynamic contact angle decreases, and then increases. In addition, when the voltage is 20V, time 30min, aluminum alloy sheet has the minimum advancing contact angle and receding contact angle, 10.22°and 68.63°, respectively. Compared to untreated aluminum–epoxy, the advancing and receding contact angles decrease 18.89° and 25.1°, respectively. And increasing the immersion speed into the resin, the contact angle of the aluminum alloy also increases.
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  Effects of power on the properties of Li2TiO3 powders prepared by microwave-assisted solution combustion

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  . 2015, 46(08): 18-0.

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  The tritium breeding material, Li2TiO3 powder, has been fabricated through microwave-assisted solution combustion synthesis (MSCS) method in one step using urea as the fuel. The dependence of temperatures on times in processes was recorded by measuring temperature system. Effects of microwave powers on combustion process, phase structure, and morphology of as-synthesized Li2TiO3 were investigated by means of XRD, FESEM，TEM and FT-IR, etc. technology. The products were compared with that by traditional solution combustion synthesis (SCS). The results show that MSCS mehod can avoid the decomposition of urea in boiling stage, and ensure the follow-up of combustion process, and with the increase of microwave power, the relative content of Li2TiO3 phase gradually increased. When the power is up to 1200 W, single phase Li2TiO3 powders can be obtained with an av-erage grain size of ~60 nm.
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  Preparation and Characterization of High Wettability Gradient Surface on Copper Substrate

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  . 2015, 46(08): 19-0.

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  Gradient wettability surface changing from the original contact angle of copper (90.8°) to surperhydrophobic (151.4°) was prepared on copper substrate via a facile chemical displacement technique, by adding dropwise AgNO3 solution into a beaker with copper foil vertically placed inside and regulating the dropping speed. By combining with the previously reported alkali-assistant-oxidation technique for creating hydrophilic wettability gradient, the high wettability gradient surface from 151.6° to 3.7° was further fabricated on the copper substrate. The copper foil may keep its gradient wettability property after immersed in water bath around 100℃ for 10 h, with a maximum change of contact angle less than 10°. The Scanning electron microscopy (SEM), X-ray diffraction (XRD) and surface topography instrument (3D) were employed to analyze the morphologies evolution and crystal structures of the Ag nanoparticles on copper substrate. The results show that the high gradient wettability surface from superhydrophilic to superhydrophobic may be constructed by depositing the hydrophilic copper hydroxide particles and hydrophobic silver particles respectively in both end parts of the copper foil and in turn forming gradient roughness structures. As the water contact angle of flat silver surface and smooth surface of copper hydroxide are 72.8 ° and 62 ° respectively, the results found in this paper may suggest another example for defining hydrophobicity and hydrophilicity by a critical contact angle of 65°.
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  Study of the Process Optimization and Corrosion Resistant of Amorphous Ni-Fe-P Alloy Shielding Fabric

  Xiao-Yi ZHANG ;

  . 2015, 46(08): 20-0.

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  A flexible shielding fabric with dense uniform coating was prepared after electrical deposition of amorphous Ni-Fe-P alloy on copper-coated polyethylene terephthalate (PET) fabric. The effects of alloy fabric ohms per square, weight gain rate and shielding effectiveness were discussed by the current density, temperature and pH value. The morphology and composition of coating of amorphous Ni-Fe-P alloy and amorphous Ni-P alloy were analyzed by SEM and EDS. The EMI shielding effectiveness and corrosion resistance were also tested. The results fabric possesses dense, smooth, and uniform coating, when the processing conditions are 60 , pH=1.5, and current density =8.7A/dm2. The alloy fabric has excellent of corrosion resistance. The EMI shielding effectiveness of this alloy fabric achieves 69.20dB-80.30dB in a broad frequency range between 300 kHz-1.5GHz.
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  Microstructure evolution and parameter optimization during hot deformation of TA12 titanium alloy

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  . 2015, 46(08): 22-0.

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  The hot deformation behaviors of TA12 alloy with the strain of 80% , strain rate range of 0.01~10S-1?and?? temperature range of 870~1070℃ was studied by using Gleeble-3800 thermal simulation machine. The true flow stress-true strain curves of TA12 were obtaind on the basis of the experimental parameters, and the influence of deformation parameters on the organization and the organization evolution were analyzed. Meanwhile， the strain rate sensitivity index m, power dissipation factor η, instability criterion ξ were calculated based on the underlying data from the stress strain curve. A variety of mechanisms of conversion produced by combined effect of stress, strain rate, deformation temperature and deformation were analyzed.Instability areas were identified by drawing instability figures further. Moreover, hot working figures were constructed though overlaying power dissipation figure and instability figure. The results show that: at low temperature, the main influence of the temperature included changes in alpha phase morphology and the number, and at high temperature, the main performance is β grain coarsening; The influence of strain rate is mainly manifested in?deformation time; The higher area of η and ξ is a good processing area, the lower instability deformation parameters area of η and ξ is an avoided processing area. the appropriate processing condition of this alloy is temperature of 910 ~ 970℃, strain rate of 0.01~0. 3 s-1.
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  Influence of AgNO3 content on the formation and optical properties of Au@Ag2S@ZnS core/shell/shell structure

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  . 2015, 46(08): 23-0.

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  Chemical reduction method was adopted to synthesize CTAB-capped Au nanoparticles, and then zinc diethyldithiocarbamate and AgNO3 as zinc source and silver source respectively were used to prepare Au@Ag2S@ZnS core/shell/shell structure based on the as-prepared Au seeds by hydrothermal method. XRD patterns show that the obtained core/shell/shell structure was composed of cubic phase Au, monoclinic phase Ag2S and hexagonal phase ZnS. UV-Vis test reveals that the SPR position can be controlled by varying the amount of AgNO3 added. SEM and TEM pictures show that the obtained samples are spheres which actually consists a lot of small nanoparticles and is polycrystalline. Photoluminescence reveals a phenomenon that the main luminescence peak presents red shifts firstly and then the intensity of it decreases without the change of the main peaks’ position when increasing the amount of AgNO3. This kind of photoluminescence phenomenon may be due to the partial incorporation of silver ions into the ZnS shell or the increase of intermediate Ag2S layer which can increase the distance between ZnS and Au.
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  Nano metal modification research of high strength magnesium alloy

  Fei ZHENG

  . 2015, 46(08): 24-0.

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  In order to improve the high mechanical properties of automobile magnesium alloys, as-cast magnesium alloy specimens have been prepared ty adding 1.5% nano titanium into Mg-3Gd-2Zn-0.5Zr magnesium alloy, of which the mechanical properties analyses at 0 ℃, 25 ℃ and 250 ℃OM, SEM, XRD analysis, have carried on, respectively. The analysis results showed that the nano titanium addition can improve the alloy mechanical properties, and significantly improve the mechanical properties, damping performance and wear resistance properties of the alloy, of which damping performance under the strain amplitude of 6×10-5, 20×10-5, 40×10-5 increased by 54%, 77% and 81%, respectively; the wear volume and friction factor at 250℃ decreased by 68% and 11% respectively. This provides further guidance and reference for nano modified studies of high strength magnesium alloy.
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  Study on preparation of hollow α-Fe2O3 magnetic nanofibers

  . 2015, 46(08): 25-0.

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  Abstract: In recent decades, magnetic iron oxide material has developed into a kind of nanomaterial with the property of magnetic targeting. Magnetic nanoscale fibers have aroused extensive concern of researchers because of the unique shape anisotropy and magnetocrystalline anisotropy which can break through the isotropic magnetic powder materials on the properties of electromagnetic limit. Electrospinning, hydrothermal synthesis and high-temperature calcination were combined successfully to prepare novel magnetic nanofibers. Scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FT-IR), thermal gravimetric analysis (TG) and X-ray diffraction (XRD) were employed to test and represent the calcination. The results indicated that the magnetic nanofiber after calcination has a novel structure of the hollow porous microstructure which shows quick and effective adsorption of methyl orange.
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  Effects of drying and calcination on the microstructure of mesoporous TiO2 powders

  Qiong CHEN

  . 2015, 46(08): 26-0.

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  Mesoporous materials have been widely used in different fields due to their special pore structures. In this work, mesoporous TiO2 powders were synthesized by sol-gel method to investigate effects of drying temperature, calcination temperature and holding time on the microstructure of mesoporous TiO2 powders. N2 adsorption-desorption method was used to characterize the specific surface area, specific pore volume and pore size distribution of TiO2 powders, and X-ray diffraction was employed to analyze the phase composition and crystallite size of TiO2 powders. It is indicated that there exists an optimum drying temperature for synthesis of mesoporous TiO2 powders. Both increase of calcination temperature and prolongation of holding time result in an increase in the average pore size and a decrease in both the specific surface area and specific pore volume of mesoporous TiO2 powders.
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  CIAS Thin Films Prepared by Vacuum Thermal Evaporation

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  . 2015, 46(08): 27-0.

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  CuIn0.7Al0.3Se2 (CIAS) thin films were prepared by vacuum thermal evaporation method on glass substrate, and annealed at 450℃in selenium and nitrogen atmosphere in vacuum.The results showed thatCIAS thin films were with chalcopyrite structure and the main preferred orientation was (112).After selenium annealing,the lattices became integrated, crystal grain sizes grown, the distribution of the composition uniformed and the composition closertothe stoichiometric ratio of the CIAS.The CIAS film wasp-type semiconductor. The band gap of the annealed film was reduced to 1.38eV. The charged carriers’ concentration of the annealed films decreased to 2.41E + 17cm-3,the mobility and resistivity increased to 5.29cm2/N-s and 4.9ohm- cm, respectively.
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  Properties of Al2O3 dispersion strengthened copper alloy prepared by internal oxidation and high-velocity compaction

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  . 2015, 46(08): 28-0.

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  Al2O3 dispersion copper alloy powder was made from Cu-0.18%wtAl alloy powder and oxidant Cu2O powder through internal oxidation. Then the powder was pressed by high-velocity compaction (HVC) followed by sintering in hydrogen at 960-1080℃ to prepare dispersion strengthened copper alloy. The forming ability of the alloy powder by HVC and the effects of sintering temperature on relative density (RD), hardness, electrical conductivity as well as compressive strength were investigated. The results show that HVC pressing Al2O3 dispersion copper alloy powder could achieve good forming ability, and the green density reaches 8.72g/cm3 (98.4%RD). Compared with the compact, RD of sintered alloy has no obvious change, while the electrical conductivity significantly improves, hardness decreases, and compressive strength increases. With increasing the sintering temperature, the electrical conductivity increases, hardness slightly decreases and compressive strength almost keeps constant. For the as-prepared alloy by sintering at 1040-1080℃, the electrical conductivity and hardness is beyond 80%IACS and 77HRB, respectively, and compressive strength reaches 453MPa. These properties of the alloy could basically meet the requirement of the practical application used as spot welding electrodes.
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  Effect of composite cellulase pretreatment on the structure of bleached wheat straw fiber

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  . 2015, 46(08): 29-0.

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  The effects of the calcination atomosphere on the properties of nano-sized Y2O3 powders

  ;Xiao-Dong LI ;;;

  . 2015, 46(08): 30-0.

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  Abstract: The effects of the calcination atmosphere on the property of Yttria nanopowders were investigated. The yttria powder were calcinated in O2 and H2 atmospheres respectively at various temperatures, and the properties of the powders were characterized by using BET, XRD, SEM and TMA measurements. The results show that powders calcinated in O2 atmosphere are of cubic phase, and are composed of near spherical particles with smaller particle size and good dispersity. Besides, the powders show lower temperature of maximum shrinkage rate under CRH sintering. On the other hand, the powders calcinated in H2 atmosphere contain a trace amount of hexagonal structure YO1.458. The particles are severely aggregated when calcinated at temperatures >1050℃, due to the occurrence of sintering between particles. Present investigation indicated that calcination in O2 is preferable to the preparation of sinterable Y2O3 powders.
综述 进展
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  High-thermal conductivity of Si3N4 ceramics: research status and development tendency

  Tian WANG;

  . 2015, 46(08): 31-0.

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  This paper deals with the recent developments of high thermal conductivity silicon nitride ceramics. The factors reducing the thermal conductivity include grain boundary phases of low thermal conductivity and lattice defeats in Si3N4 crystals. In this paper, reducing the number of grain boundary phase and the amount of lattice oxygen, changing the way of grain boundary phases exist are discussed to choose the suitable raw material and sintering additive, and high thermal conductivity Si3N4 ceramic can be obtained.
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  The preparation and application of structured biomimetic surface

  . 2015, 46(08): 32-0.

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  As an important and prospective subject in the field of composite materials, structured biomimetic surface is a new type of multidisciplinary cross area which is developed in recent 30 years. It has wide applications in industrial field, biological engineer field, medicine field, military field, energy field and daily life. The applications of structured biomimetic surface in the fields of adhesion and resistance reduction and superhydrophobicity are discussed, latest preparation methods of structured biomimetic surface and their advantages and disadvantages are also introduced in this paper. Besides, outlook on the structured biomimetic surface are predicted.