bluuebunny/crossref_metadata_2025 huggingface dataset:
Dry Water: a Prospective Material for Methane Storage via Clathrate Hydrate Form
Authors: Liu Chang Ling , Hu Gao Wei , Ye Yu Guang , Meng Qing Guo
Published: December 2011

Dry water (DW) is a powder-like, solidified form of water, where water droplets are surrounded by silica nanoparticles. DW is considered to be an effective medium for gas storage because it can slurp up gases which combine the water molecules to form clathrate hydrate. In this paper, DW was prepared by mixing water and hydrophobic silica particles (H18) at high speeds, and based on which, dry water methane hydrates (DW-MH) were synthesized under certain conditions. The characteristics of DW and DW-MH were investigated by Raman spectroscopy. The results show that DW-MH is a typetical sI clathrate hydrate with hydration number around 5.9. The storage capacity in clathrate hydrate prepared with methane and four different materials, i.e. DW, powder ice, Sodium Dodecyl Sulfate (SDS) solution and liquid water, was measured by volumetric method. The results showed that DW is prospective medium for gas storage that can increase much higher of the storage capacity compared to other materials.
Photoelectrical and Photovoltaic Peroperties of n-ZnO/p-Si Heterojunction
Authors: Xu Yan Li , Li Jin Hua
Published: December 2011

n-ZnO thin films doped In with 2 atm.% were deposited on p-type silicon wafer with textured surface by Ion Beam Enhanced Deposition method, after annealing and prepared front and back electrodes, the n-ZnO/p-Si heterojunction samples were fabricated. The photoelectric property of the sample were measured and compared with silicon solar cell. The result indicated the saturated photocurrent of n-ZnO/p-Si heterojunction was 20% greater than one of the Si solar cell. It means the ZnO/Si heterojunction has a higher ability of produce photoelectron then one of silicon solarcell. The result of the photovoltaic test of n-ZnO/p-Si heterojunction show The open circuit voltage and short-circuit current of the n-ZnO/p-Si heterojunction was 400mV and 5.5mA/cm2 respectively. It was much smaller than the one of silicon solar cells. The reason was discussed
Appraisal about Stainless Steels for Piercing Jewelry
Authors: Yuan Jun Ping , Li Wei , Wang Chang , Ma Chun Yu
Published: December 2011

This paper introduced several conventional stainless steels for piercing jewelry, and discussed their corrosion resistance, nickel allergy problem and risk of piercing infection. The authors proposed that several requirements should be taken into consideration in developing stainless steel materials for piercing jewelry, including corrosion resistance, safety, anti-bacterial, castability, workability, weldability, surface treatment property, and etc. High nitrogen and nickel free or low nickel stainless steels with anti-bacterial performance, which had many unique characteristics such as excellent corrosion resistance, no nickel allergy and less risk of piercing infection, would become a new development trend of stainless steels for piercing jewelry.
Preparation and Morphology of SMPU/PNIPAM Semi-IPN Microporous Membrane
Authors: Zhao Shu Mei , Dai Zheng Wei , Lv Hai Ning , Xue Yuan
Published: December 2011

Microporous membranes were prepared by immersion precipitation phase inversion method from the semi-interpenetrating polymer network (semi-IPN) of shape memory polyurethane (SMPU) and poly (N-isopropylacrylamide) (PNIPAM). The influence of material compostion and preparation procedure on the morphology of membranes such as pore structure and porosity was investigated by methods including Fourier-transform infrared (FT-IR) spectroscopy and scanning electronic microscopy (SEM). Both sponge-like structure and large-pore structure were found in the membranes. The introduction of PNIPAM content in the semi-IPN promotes the formation of large-pore structures and increases the porosity of membranes, due to the improvement of water diffusion into the casting solution. We also found that by increasing the temperature of coagulation bath and the concentration of DMF in the coagulation solution, the formation of large pores could be impeded, and membranes with more sponge-like structure could be prepared.
Effect of Texture on Secondary Work Embrittlement of IF Steels
Authors: Wu Qing Song , Zhu Hong Chuan , Zhao Jiang Tao , Sun Fang Yi , Hu Kuan Hei
Published: December 2011

The relationship between texture and secondary work embrittlement of interstitial-free steels was studied by X-ray analysis technique and scanning electron microscopy analysis technique. The results indicated that the stronger the γ fiber texture was, the higher the plastic strain ratio (r-value) was, and Secondary work embrittlement temperature rose as r-value increased or γ fiber texture intensified. The mode of secondary work embrittlement fracture was a blend of cleavage fracture and intergranular fracture, and the fraction of cleavage fractures decreased gradually as secondary work embrittlement temperature rose.
Thermal-Oxidation Degradation of Microwave Drying Nature Rubber
Authors: Zhang Fu Quan , Huang Mao Fang , Chen Mei , Wang Yong Zhou , Liao Jian He
Published: December 2011

The effects of drying methods on thermal-oxidation degradation and ageing behavior of nature rubber (NR) was investigated using Fourier transform infrared/Attenuated total reflection (FTIR-ATR) and thermogravimetric analysis. Examining the samples of thermal-oxidation ageing for 24h by FTIR-ATR spectroscopy allowed appearance of obvious carboxyl absorption of hot-air drying NR at 1723cm-1, decay of methylene stretch and C=C plane stretch during thermal-oxidation ageing process, to be monitored. TG and DTG were used to determine thermal-oxidation degradation temperature in air atmosphere and active energy using Coats-Redfern equation. Showed from the results, the degradation temperature and active energy of microwave drying NR was higher than hot-air drying, thermal-oxidation resistance was more excellent by FTIR analysis, indicating a higher thermal-oxidation stability of microwave drying NR.
Influence of Cutting Parameters on Surface Characteristics for Milling Powder Metallurgy Nickel-Based Superalloy
Authors: Qiao Yang , Ai Xing , Liu Zhan Qiang
Published: December 2011

Powder metallurgy (PM) nickel-based superalloy is regarded as one of the most important aerospace industry materials, which has been widely used for engine components. As the demands of the service performance increase, the surface characteristics are becoming more and more important. However, the machined surface of PM nickel-based superalloy is easily damaged due to its poor machinability. A series of milling experiments in a wide range of speeds were carried out to investigate the effects of dry milling parameters on the surface characteristics of PM nickel-based superalloy. The machined surface is evaluated in terms of surface roughness and work hardening. The results show that, milled surface characteristics of PM nickel-based superalloy are sensitivity to the cutting speeds. The machined surface roughness increases with increase of the cutting speed, but with further increase of cutting speed between 70 to 90 m/min and 150 to 170 m/min two decreases in surface roughness appear. For work hardening, it can be seen that the machined workpiece surface hardens seriously.
Effects of Electromagnetic Stirring on Morphology Evolution of Primary Phase in Semisolid Alloy
Authors: Liu Zheng , Liu Xiao Mei
Published: December 2011

The effects of electromagnetic stirring on the morphology evolution of primary phase in semisolid A356 alloy slurry prepared by low superheat pouring and slightly electromagnetic stirring (LSPSES) were studied. The results indicated that the slurry containing globular-like primary phase was prepared by LSPSES, and the electromagnetic stirring within range of stirring power studied had the obvious effect on the morphology of primary phase in the slurry. The morphology of primary phase with finer size slurry was evoluted to globullar-like with increase of stirring power.
Structure Analysis and Optimization of Precision Grinding Machine Bed
Authors: Yang Wei , Lin Xiao Hui , Guo Yin Biao , Lin Jing , Jiang Tao
Published: December 2011

This work presents a research on the static structure and modal analysis of precision grinding machine bed. The solid model is created with 3D design software SOLIDWORKS and analyzed by FEA software ANSYS. In order to alleviate the influence of deformation and vibration on precision grinding machine bed, some factors that can influence mass, max displacement and model frequency ware are analyzed. According to of analysis results, an optimization is carried out to determine the dimension and structure of precision grinding machine bed. Compared to the initial structure, the deformation of the optimal structure is less and inherent frequency is higher.
Simulation Analysis of Drag-Reduction Effect by Dimpled Surfaces with Quasicrystal and Crystal Lattice Arrangment
Authors: Zhang Yao , Geng Xing Guo , Zhang Meng , Wang Xiao Na
Published: December 2011

Based on the experimental results that two-dimensional dimpled surface structure arranged in 12-fold quasicrystal lattice could effectively reduce drag, a model of two-dimensional Fraunhofer diffraction wave is built in this paper to simulate and analyse the effect characteristics of disturbed waves which generated by two-dimensional quasicrystal and periodic crystal structure. The simulated results show that the intensity distribution of diffraction peaks with 12-fold quasicrystal structure is more uniform and the intensities of diffraction peaks are much smaller in the streamwise direction than that of other structures, meanwhile along spanwise direction it has less strong diffraction peaks, from which it can realize effective drag reduction.
Crystal, Electronic and Magnetic Structure of Co and Ag Doped Rutile TiO2 from First-Principles Calculations
Authors: Zhang Li Kun , Wu Bo , Wang Min , Chen Lu , Ye Guo Xin , Chen Tuo , Liu Hai Long , Huang Chao Ran , Li Jing Lin
Published: December 2011

The crystal structure, electronic structure and ferromagnetic properties of the transition metals M (where M=Co, Ag) doped rutile TiO2are studied by using first-principles calculations based on the density functional theory (DFT) and projector augmented wave (PAW) pseudo-potentials (PP) method. In the doped system M2Ti14O32, the two doping atoms tend to align along c axis in the stablest configuration state. When M represents Co atom, the ferromagnetic state is favorable with magnetic moments of 0.99μB per Co atom, while Ag2Ti14O32has no magnetic moment. Doping atoms induce new energy level, which reduces band gap, decreases Fermi energy level and thus considerably affects the optical absorption and photocatalytic activities of TiO2under visible light irradiation.
Numerical Simulation of the Relation between Plasma Reflection and Keyhole Dimension in the Keyhole PAW Process
Authors: Yin Feng Liang , Zhu Sheng , Hu Sheng Sun
Published: December 2011

A three-dimensional mathematical model has been established to research the relation between the plasma reflection and status of keyhole during the keyhole PAW processing. It has been found that the strength of the plasma reflection is related to the keyhole dimension. Another condition to make the plasma refection appearance is that the keyhole or concave in the pool must be unsymmetrical about the axis of the plasma arc. The mechanism of detecting circuit designed based on the fact that the plasma refection is able to indicate the status of keyhole is mathematically studied. The result shows that the voltage signal in the detecting circuit can be used to indicate the status of keyhole.
Directional Solidification Microsegregation and Concentration Analysis with Different Supersaturation
Authors: Chen Da Hui , Hou Li Qun , Tang Jin Jun , Ren Zheng , Fei Liang Jun , Kang Zhen Yu
Published: December 2011

In order to obtain the directional microstructure of different supersaturation and growing velocity, three simulations is calculated with different initial temperature. When the initial temperature is 1576K, and the supersaturation and growing velocity are smaller. The average space length of columnar crystals is bigger, and microsegregation is smaller. when the initial temperature is 1574K, the supersaturation and growing velocity increase. The average space length of columnar crystals decreases, and microsegregation increase; when the initial temperature falls to 1566K, the supersaturation and growing velocity reach 1.176 and 3.238 cm per second. The microsegregation decreases rapidly. The average space length of columnar crystals is the smallest. The solute curve of columnar crystal is like a “U” figure. When the growing velocity is bigger than VA, the phenomenon of solute trapping takes place.
Effect of Solution Treatment Time on Microstructure and Martensitic Transformation Point of C250 Steel
Authors: Hua Xiao Zhen , Wei Zhen Wei , Peng Xin Yuan , Cui Xia , Zhou Xian Liang
Published: December 2011

The morphology of microstructure and PAG was observed by means of LEICA DMIRM metallurgical microscope, the phase was measured by D8 ADVANCE X-ray diffractometer (XRD), and the martensitic transformation point is tested on DIL805A dilatometer after ST. The results show that the PAG size of C250 steel has not a clear growth. The recrystallisation has the priority of nucleation in the PAG boundary. The morphology of martensite presents irregular bans and stringers before recrystallisation, whereas presents blocky thereafter. The intermetallic compounds re-dissolve by ST. With the prolonged of ST time, the Ms point increases before recrystallisation, decreases thereafter; the Mf point does not have a clear change.
Effect of Thermal Input on Finite Element Predictions of Welding Residual Stresses
Authors: Wu Ai Hui , Syngellakis Stavros , Mellor B. G.
Published: December 2011

A two-dimensional finite element simulation of a welding process is developed for predicting temperature histories and residual stresses in a structural steel butt-welded joint. The purpose of the simulation presented in this paper is the assessment of the effect of uncertainties in thermal material, loading and constraint input on both the thermal and mechanical analysis predictions. The model is validated by comparison with previously welded and tested specimen with published residual stresses measurements. Residual stress results are not sensitive to the thermal analysis input even if the latter has significant influence on temperature distribution. Modelling boundary conditions for both thermal and stress analyses, was identified as a key factor affecting predictions of residual stresses and distortion.
Study on Surface Modification of Ammonium Nitrate
Authors: Wei Yanan , Cai Bao Hu
Published: December 2011

This article studied on the surface modification of ammonium nitrate by the liquid coating technology , choosing separately polyvinyl acetate (PVAC), sliced paraffin (Wax),polyethylene glycol (PEG) as coating materials. The samples were characterized by SEM and DSC. The experimental results showed that the modification effects of PVAC and Wax were good. The appearance of modified ammonium nitrate presented spherical, and flowing property was better. Their moisture absorption descended respectively by 30.6%, 23.3% after 24 hours at ambient temperature 30°C and relative humidy 75%.
Feature-Based Volume Decomposition for Robotic Weld Deposition-Based Rapid Prototyping
Authors: Zhu Sheng , Yin Feng Liang , Liang Yuan Yuan , Liu Jian
Published: December 2011

A feature-based volume decomposition algorithm for robotic weld deposition-based rapid prototyping has been proposed to eliminate or reduce the use of support structure which decreases the building efficient. The algorithm decomposes the model volume into shapeable feature volume and un-shapeable feature volume firstly, according to the slope angle is greater or smaller than the critical slope angle. Un-shapeable feature volume is decomposed further into sub-volume until each sub-volume to be shapeable without support structure. Each feature volume or sub-volume may be assigned with different building orientation and building sequence in the process planning process. The model volume of a classical part was decomposed by this method to validate this method’s ability of eliminating the use of support structure.
Influencing Time Response of Nano Photoelectric on the Factors Films
Authors: Dai Hong Xia
Published: December 2011

Photoelectric film is an important information functional material transforming optical signals into electric signals. Composite dielectric photoelectric films formed by burying metal nanoparticles in semiconductors are different from traditional photoelectric films and semiconductor films, which will show special performance and may be applied in high-speed optical and optoelectronic devices. time response of photoelectrons to emission increases with the increase in the energy of incident photons; when the surface barrier decreases, response time increases; The smaller the film thickness is, the faster the time response of photoelectrons will be.
Study on Mechanism of Rock Fragmentation of TBM Disc Cutter
Authors: Hong Kai Rong , Liu He Ping , Zhang Wei
Published: December 2011

As the interaction mechanism between disc-cutter and wall rock is the key to the TBM performance of breaking-rock, many exports who come from different countries have so far made a great deal of studies, tests, analyses and modeling works and many models of mechanism of rock-fragmentation were achieved. Some new corrections are made constantly according to the experiences accumulated from engineering practice. This paper summarizes the works of the scholars and some analyses and comparisons are made. Based on the CSM and NTNU, a new model is presented to takes into account some ingredients, which would influence the efficiency for TBM to break wall rock. To enhance the level of design, manufacture and operation of TBM, the databases for rock attributes, main parameters of TBM and excavating parameters should be found.
Study on Nano-SiO2 Measured by Atomic Force Microscope
Authors: Jing Zhang , Cao Qi Zhi , Li Jian Ying
Published: December 2011

The morphology and structural evolution of nano-SiO2powers obtained by pressuring samples and sintering in muffle at different temperatures were studied by X-ray diffraction (XRD) and atomic force microscope (AFM). The experimental results show that the particle sizes of nano-SiO2increase with temperature rising, and it meets the physical mechanism of particle growth.
Fatigue Behavior of Cast Steel ZG20SiMn under Stain Control Mode
Authors: Li Yuan Yuan , Li Feng , Che Xin , Chen Li Jia
Published: December 2011

Abstract: The fatigue behavior of cast steel ZG20SiMn under strain control mode was investigated, and the influence of imposed total strain amplitude on the cyclic deformation and fracture behavior of the cast steel ZG20SiMn was determined. The experimental results reveal that during fatigue deformation, the cast steel ZG20SiMn may exhibit the cyclic strain hardening and stable cyclic stress response behavior, which mainly depends on the imposed total strain amplitude. The relationship between plastic and elastic strain amplitudes with reversals to failure shows a single linear behavior, and can be well described by the Coffin-Manson and Basquin equations, respectively. At different total strain amplitudes, the fatigue cracks initiate at the free surface of fatigue specimens and propagate for the cast steel ZG20SiMn.
The Studies on the Thermophysical Properties of Binary Systems of Neopentylglycol and the Derives
Authors: Wang Xiao Wu , Wang Yin Er , Zhao Chao Qiong
Published: December 2011

Specific capacity and thermal conductivity are two very important physical quantities that characterize the heat performance of heat storage material. This paper measured the specific capacities and thermal conductivities of binary systems formed by NPG、TRIS and PE in the temperature range from 30oC to 70 oC and analyzed the experimental results from the point of view of crystal vibration. Hydrogen bonds exert great influence on the thermophysical properties of the binary systems. Although the components are only simply blended, substitutional impurity defects are incurred. As a result hydrogen bond will be affected in a complex way. There is no uniform trend between the value of x and specific capacity. Because of the influence of structure defect, specific capacity and phonon speed which all change with the strength of hydrogen bond, the relationship between thermal conductivity and the value of x is non-linear too. Because 40oC is near the phase transition temperature of NPGxTRIS1-x (x=0.618), its specific capacity at 40oC decreases and thermal conductivity increases. Because hydrogen bond changes with temperature, specific capacity of PExTRIS1-x (x=0.618) rises. Since 60oC is near the phase transition temperature, its specific capacity at 60oC falls. PExTRIS1-x (x=0.618) shows smaller thermal conductivities at temperatures higher than 30oC. This is because the hydrogen bonds become weaker with temperature. Blending impurities possessing longer mean free path with polyalcohol can change the thermal conductivity.
Effect of PEG on Stability of Alkalinity Silica Sol
Authors: Wang Juan , Sun Ming , Gao Bao Hong , Wang Ru , Liu Yu Ling
Published: December 2011

It is known that the rate of coagulation depends mainly on the stability of the colloidal particles and that the solution pH and potential are the main factors affecting the colloidal stability. The stability of dispersion (the ability of the dispersion to resist coagulation) may be related to its kinetic stability, which in turn depends on the force barrier preventing collision between the particles and thus preventing their coagulation. The addition of surfactant can change the pH and the potential of silica sol. So PEG is select to improve the stability of silica sol. The results presented here show that surfactant, PEG, has a strong consequence on the stability of silica dispersion. With the molecular weight increasing, the stability of silica sol is weakening.
Ni-Coated Carbon Nanotubes/Mn-Zn Ferrite Composite as Viable Microwave Absorbing Materials
Authors: Wang Wen Jie , Zang Chong Guang , Jiao Qing Jie
Published: December 2011

This paper presents the design, development and characterization of the spinel ferrite [Mn0.2Zn0.8Fe2O4] powders and Nickel (Ni)-coated multiwall carbon nanotubes (MWNTs). A combination of Mn0.2Zn0.8Fe2O4 spinel ferrites particles and Nickel (Ni)-coated multiwall carbon nanotubes (MWNTs) were introduced into epoxy resin to be a microwave absorber. The structural characterizations and surface morphology of Mn0.2Zn0.8Fe2O4 and MWNTs were investigated by X-ray diffraction (XRD) and scanning electron microscopy respectively. The electromagnetic wave absorption characteristics of the composites have been studied in the frequency interval of 12-15GHz.The results for Mn0.2Zn0.8Fe2O4/EP, Mn0.2Zn0.8Fe2O4/MWNTs/EP and Mn0.2Zn0.8Fe2O4/Ni-coated MWNTs/EP microwave absorbers for the same thickness have been reported. It has been found that the Mn0.2Zn0.8Fe2O4/Ni-coated MWNTs/EP composites show the broadband characteristics with minimum absorption of 5 dB about 2.6 GHz and the maximum absorption of 37.05 dB at 14 GHz for a coating thickness of 2 mm. Therefore, Mn0.2Zn0.8Fe2O4/Ni-coated MWNTs/EP composites will be a suitable microwave absorptive material for 12-15GHz.
Effect of Sintering Temperatures on the Reaction-Bonded Si3N4/SiC Composite Ceramics
Authors: Li Jun , Yuan Wen Jie , Wang Shuo , Zhu Hong Xi , Deng Cheng Ji
Published: December 2011

Effect of sintering temperatures on reaction-bonded Si3N4/SiC composite ceramics under pressureless was investigated. Si3N4/SiC composite ceramics were sintered at different temperatures from 1450 to 1700 °C under nitrogen atmosphere by using SiC with different particle sizes, Si and additives Y2O3 as raw materials. The phases, microstructure and mechanical property were characterized by XRD, SEM, and compressive strength tests. The results demonstrated that when the particle gradation consists of silicon carbide of 74 μm (5 wt.%), 44 μm (10 wt.%) and 0.5 μm(35 wt.%) and silicon powder of 74 μm (42 wt.%), the more dense samples with the bulk density of 2.43 g/cm3 and the higher compressive strength of 324 MPa could be obtained at the sintering temperature of 1550 °C for 3h as the optimum processing parameters.
Preparation of AlN-ZrO2(Ca) Composites by Hot Pressed Sintering
Authors: Chen Xian Tao , Bu Jing Long , Wang Rong Lin , Chen Jun Xing
Published: December 2011

AlN-ZrO2composites were prepared by hot pressed sintering with AlN particle (d≈2mm, d≈1.5mm and d≈1mm) and ZrO2powder as material. Its phase composition, thermal conductivity and sintering performance were investigated by XRD, SEM, EDS and performance testing. The results showed that AlN could be reserved in samples, and the thermal conductivity and the apparent porosity of the samples ascended with increase of the content of AlN, and the bending strength of the samples with same AlN particle occurred change according to V-shape with content of AlN increasing. Thereinto, the thermal conductivity of the samples with 1.5mm AlN was most excellent, amang samples with AlN particle of 2mm, 1.5mm and 1mm, and sintering performance of the samples with 1mm AlN was best. Particle interface of AlN and ZrO2was high concentration area of elements Ca and O, and was a structural loose crack area with CaAl12O19formed. The area is abominable for performances of AlN-ZrO2composites such as thermal conductivity, density and strength. It is more appropriate for preparation of AlN-ZrO2composites with AlN particle of 1.5mm and 1mm as materials.
In Situ Polymerization Approach to Magnesium Hydroxide-Reinforced PA6 Composites
Authors: Xu Li Li , Deng Yu Hao , Wang Ye , Liu Chang Hua , Liu Sheng Peng
Published: December 2011

Polyamide 6 (PA6)/magnesium hydroxide (MH) nanoparticles composites have been prepared by in situ polymerization of ε-caprolactam in the presence of pristine MH and γ-aminopropyl-triethoxysilan ( KH550 ) grafted MHs (MMH). Compared with pure PA6, the tensile strength and elongation at break of PA6/MH and PA6/MMH composites shown obvious increasement and attain maximum at loading of 3 wt% MHs. The tensile strength and elongations at break of PA6/MMH composites exhibited notably enhancement contrast with that of PA6/MH composites. Comparing with PA6/MH composites, the izod impact strength of PA6/MMH composites were also improved. Scanning electron microscopy (SEM) shown that MMH particles were homogeneous dispersed in PA6 matrix due to the surface modification of grafting KH550.
Effect of High-Temperature Heat Treatment on Mechanical Property of Cr-Geopolymer Composite
Authors: Wang Mei Rong , Zheng Yi , Jia De Chang , Zhou Yu
Published: December 2011

Chromium powder reinforced geopolymer composite (Cr/geopolymer) was prepared in order to enhance its thermal conductivity and mechanical properties. The phase composition, microstructure and mechanical properties of Cr/geopolymer before and after heat treatment at 900, 1000, 1100 and 1200°C were investigated by the X–ray diffraction (XRD), scanning electron microscopy (SEM) and three–point bending test. With increasing heat treatment temperature from 900 to 1100°C, mechanical property of Cr/geopolymer increased gradually and at 1100°C flexural strength got the peak value, which was 325% higher than that of specimens without heat treatment. Cr/geopolymer treated at 900°C did not completely transform into crystalline phase, and many micro cracks around the chromium particles were observed. Cr/geopolymer treated at 1000–1100°C completely crystallized into leucite phase, and the metal chromium remained its original state. Meanwhile, most of the micro cracks were closed. When the temperature further increased to 1200°C, many visible defects were observed in Cr/geopolymer, and chromium oxide appeared in the interface of Cr/geopolymer, which had detrimental effect on the heat conduction and mechanical property of the composite.
Properties of Jute Fibers Reinforced Friction Materials
Authors: Ma Yun Hai , Jia Su Qiu , Wang Bao Gang , Ye Wei , Tong Jin , Jia Hong Lei , Wen Shuang
Published: December 2011

Jute fibers reinforced friction materials were prepared by mold and heat treatment. The friction coefficients of 3wt.%,9wt.% and 12wt.% jute fibers reinforced friction materials were bigger than that of the materials without jute fibers in the heating condition. The friction coefficient of 6 wt.% jute fibers reinforced friction materials was bigger than that of the materials without jute fibers below 250°C. The friction coefficient of jute fibers reinforced friction materials deceased with the temperature decrease in the cooling condition. The friction coefficient of the materials with free-jute fibers raised from 350-250°C and reduced at the temperature lower than 250°C.Wear rates of the friction materials raised with temperature rise for jute fibers carbonization led to the matrix became loose. With jute fibers content rise worn surface of the reinforced materials became from smooth to rough. There were pits, grooves, abrasive particles, pulled out ﬁbers and wear debris on the worn surfaces. Abrasive wear was the main wear mechanism.
Low Temperature Combustion Synthesis and Characterization of Pr-CeO2 Doped with Zr Red Ceramic Pigments
Authors: Yang Li Dan , Ye Ming Quan , Han Ai Jun
Published: December 2011

New inorganic pigments Ce0.95ZrxPr0.05-xO2(x = 0, 0.01, 0.02, 0.03, 0.04, 0.05) based on CeO2-ZrO2-Pr6O11solid solutions were synthesized by low-temperature combustion synthesis (LCS) method using citric acid as a reductant and metal nitrate as an oxidant. The pigments are CeO2solid solutions doped with praseodymium and zirconium ions, and display colors ranging from dark brown via brick red to bright cream. The prepared pigments were characterized by X-ray powder diffraction, transmission electron microscopy, ultraviolet-visible absorption spectroscopy and colorimetrical measurements. Results show that cubic fluorite structure solid solution of 100 nm Ce0.95ZrxPr0.05-xO2particles can be obtained at 1000 °C. There was an effective absorption of visible blue and green in 600 nm, which is originated from the shift of charge transfer band in CeO2by doping of zirconium and praseodymium ions. Effective red hue was obtained for Ce0.95Zr0.02Pr0.03O2composition, which exhibited better L*, a*,and b* values (57.64, 23.83 and 23.78). The coloring mechanism is based on the introduction of an additional electronic energy level of unpaired 4f electron of the lanthanide ion into the cerianite forbidden band. Furthermore, the doping of Zr in Pr-CeO2system raises the slope of the absorption edge with a blue shift resulting in enhanced lightness. The prepared pigments were prospective to be alternatives for toxic pigments used in coloration of plastics.
Micromechanical Analysis of Single-Fiber Pull-Out Test of Fiber-Reinforced Viscoelastic Matrix Composites
Authors: Zhu Da Sheng , Gu Bo Qin
Published: December 2011

A micromechanical model for single-fiber pull-out test of fiber-reinforced viscoelastic matrix composites is established. It includes fiber, interphase and viscoelastic matrix. The formulas to calculate the fiber axial stress, the interphase shear stress, and the matrix axial and shear stress are obtained. Moreover, for Kevlar aramid fiber reinforced viscoelastic matrix composites, the influences of the interphase thickness, the fiber embedded length and volume fraction on the stress distributions of fiber and interphase is studied. Some analysis results show that, with the increase of normalized fiber axial distance, the fiber axial stress increases monotonically, but the interphase shear stress decreases. The stress distributions of fiber and interphase change with the variation of the interphase thickness, the fiber embedded length and volume fraction.
Morphology and Optical Properties of Nickel Oxide Nanostructure from Aqueous Solution
Authors: Hamid Muhammad Azmi Abdul , Abu Bakar Maria , Jalar Azman , Shamsudin Roslinda , Ahmad Ibrahim
Published: December 2011

In this paper, porous flower-like nickel oxide (NiO) on glass substrates were prepared by an aqueous chemical growth based technique. The morphology and optical observed were found to be influence by the reaction time. Field Emission Scanning Electron Microscopy (FESEM) revealed a porous flower-like structure growth on the substrates investigated. The optical band gap for NiO thin film calculated from transmission spectra has increased from 3.72 eV to 3.91 eV with the increasing of reaction time. This result shows that the growth time have some influence on morphology and optical of NiO films.
Effect of Polyacrylamide Hydrogels on Synthesis of Hollow Sodalite Spheres
Authors: Han Li , Wang Qin , Guo Cun Biao , Zhao Long , Guo Shi Ling , Chen Yi Liang , Zhang Rui
Published: December 2011

Hollow sodalite spheres were prepared in water-soluble polymer polyacrylamide hydrogels (PAM) which were used as "soft template". The samples were characterized by XRD and SEM. The influence of the contents of initiator (ammonium persulfate) and crosslinker (N,N’-methylene-bis-acrylamide) on the size and morphology of hollow sodalite spheres was investigated. The results showed that the pore sizes of hollow sodalite spheres significantly decreased and the shell thicknesses thickened as the amount of initiator increased. The amount of MBAM affected the crystallization of sodalite, stacked arrangement and hollow structure. When the amounts range of MBAM was 0.8%-1.6%, hollow sodalite spheres were non-friable and smaller than the others, and their arrangement was uniform and orderly.
Effect of Additives on the Expansion Behavior of Alumina-Spinel Castables
Authors: Jia Quan Li , Zhang Yu Cui , Ye Fang Bao
Published: December 2011

Alumina–spinel castables were prepared using tabular alumina and coarse spinel as aggregates, calcium aluminate cement, fused alumina fines, spinel fines and ultrafine alumina as matrixes. Effect of microsilica and dispersant on the properties of alumina–spinel castables were investigated in this paper. The results show that with the same content of microsilica addition, the values of permanent linear change and apparent porosity of samples with different additives fired at 1500°C and 1600°C are noticeably increased. The maximum expansion value is 2.01%, 1.47% and 2.59%, respectively, for Sample B (additive: FS 10), Sample E (additive: sodium tripolyphosphate) and Sample F (additive: sodium tripolyphosphate +H3BO3). There is a decrease in the final expansion value with the soaking time increases, which is associated to the sintering shrinkage of the castables in this temperature range under a compression load of 0.2 MPa, Expansion behavior of alumina–spinel castables is much different with different additive addition due to abrupt CA6 crystal growth.
Preparation and Photocatalytic Property of TiO2/C
Authors: Tian Li Hua , Liu Xia , Liu Hui Tao , Gao Yuan
Published: December 2011

Carbonaceous polysaccharide microsphere with strong adsorption ability has been successfully synthesized under hydrothermal conditions, using glucose as the carbon source. The carbon microsphere (CMS) proved to be an effective adsorbent for the removal of formaldehyde. The obtained TiO2/C nanocomposite proved to be more favorable in degrading organic pollutants than that of naked TiO2. The research is expected to be useful in industrial application for the indoor air purification and removing of trace organic pollutants in water.
Gas Response for Ethanol of SnO2 Nanorods as Sensing Materials
Authors: Li Yue Huan , Liu Yong Jun , Xiao Xue Chun , Kan Hu En , Zhao He Yun
Published: December 2011

SnO2nanorods with rutile structure were successfully synthesized by solid state reaction in the presence of NaCl-KCl. Indirect-heating sensors based on nanorods were fabricated and investigated for the gas sensing properties to ethanol. The results showed that the response of sensor to 1000 ppm ethanol is up to 114.3, the export voltage to 1 ppm ethanol can attain 2.0 V at 275 °C, and the response time and recovery time are no longer than 10 s.
Studies of 3d Electrons and Hyperfine Interactions in Ordered and Disordered Fe50Al50 Alloys
Authors: Huang Yu Yang , Qin Li Yuan , Tian Qin Guan , Li Yu Xia , Deng Wen
Published: December 2011

The positron annihilation techniques and Mössbauer spectroscopy have been used to study the signals of 3d electrons and the hyperfine interactions in ordered and disorder Fe50Al50alloys. The results show that the signals of 3d electrons of ordered Fe50Al50alloy is very low. Mössbauer spectrum of ordered Fe50Al50alloy shows a singlet, this alloy is paramagnetic. However, Mössbauer spectrum of Fe50Al50powder being ball-milled for 70 h shows a discrete sextet, indicating a decrease in the long-range order within the Fe50Al50powder being ball-milled for a long time.
Gamma Irradiation Effect on Load-Deflection Curve of Semiconductor Package
Authors: Jalar Azman , Wan Yusoff Wan Yusmawati , Othman Norinsan Kamil , Abdullah Shahrum , Abdul Rahman Irman
Published: December 2011

The effect of different doses of gamma radiation (0.5 Gy, 1.5 Gy, 5.0 Gy, 10.0 Gy and 50 kGy) on the maximum load and deflection of the Single Die Quad Flat No Lead (SDQFN) semiconductor package has been investigated. The three-point technique was carried out to obtain the maximum load and deflection of the package. The results of irradiated SDQFN show the decreasing in their maximum load and deflection with the increasing of gamma irradiation dose. The higher gamma irradiation dose produced the more significant change in the load-deflection behaviour of the irradiated SDQFN. The package becomes prone to failure when exposed to the radiation environment.
Molecular and Crystal Structure Analysis of an Oxalate-Bridged Sodium 2D Polymer: [Na(μ1,1,2,3-Oxalato)(di-μ1,1-H2O)]N
Authors: Li Jia Ming , Xu Shu Qing , Shi Zhong Feng
Published: December 2011

The title compound, [Na(μ1,1,2,3-oxalato)(di-μbelongs to triclinic, space group P-1 with a = 5.6982 (11), b = 6.5040 (12), c = 6.6647 (13) Å, α = 75.040 (2), β = 84.990 (3), γ = 70.072 (3), V = 224.34 (7) Å3, C2H3NaO5, Mr = 130.03, Z = 2, Dc = 1.925 g/cm3, μ = 0.270 mm–1and F(000) = 132. Each sodium ions is located on crystallographic inversion symmetry centre and surrounded by six oxygen donors from three oxalate ligands and two di-μ1,1-waters in a distorted octahedron geometry. Two planar 4-member cyclβes crystallographic inversion are found in alternate repeated Na2O2subunit, which is further extended to two dimensional supermolecular fragment via μ1,1,2,3-oxalato-bridged. The crystal structure is aggregated to a 3D network through O-H…O hydrogen bonding involving the water molecules and oxalate oxygen atoms.
The Research about the III-Nitride Compounds Epitaxially Grown on Si Substrate
Authors: Zhao Ai Ping , Deng Hong , Liu Feng , Deng Xue Ran
Published: December 2011

The III-nitride compounds epitaxially grown on Si substrate have attracted more and more attentions and some progress have been achieved. Many methods have been tried to tackle the issue which caused by the large lattice mismatch and thermal expansion coefficient mismatches between silicon substrate and the III-nitride compounds. This paper presents buffer layer technology, selective area and lateral epitaxial over growth technology, and presents the researches about the III-nitride devices. Semi polar and non-polar GaN films grown on Si (such as Si(110), Si(112), Si(001) et al.) also have been instructed. At the end of this paper, the development trend of epitaxial technology has been discussed.
Effects of Operation Parameters on Desulphurization of Hot Metal with Passive Magnesium and Calcium Oxide in CSP Plant of WISCO
Authors: Cao Tong You , Sun Wei , Liu Kai
Published: December 2011

The effects of operation parameters on desulphurization of hot metal with passive magnesium and calcium oxide injection in CSP plant of WISCO. have been studied in this paper. On basis of industrial optimization trials’ results on hot metal desulphurization, the original desulphurization process had been modified. Through the new-developed desulphurization process, desulfurizer consumptions have been decreased a lot by 40% with passive magnesium and 34% with lime respectively. Economical profits can be seen from the desulphurization process.
Study on Fluid Flow in a Large Round Bloom Continuous Casting Mold
Authors: Zhong Liang Cai , Zhang Mao Qiang , Liu Xi Hai
Published: December 2011

The fluid flow in an 800 mm diameter bloom mold from two kinds of submerged entry nozzles (SEN) was investigated numerically with a mathematical model and experimentally in a water model. It was shown from the research results that the impacting depths measured in the water modeling experiments are in good agreement with the ones from the numerical calculation. The impacting depths obtained from the 4-port down 5° SEN are 140~220 mm at immersion depths from 100 to 180 mm, while those from 5-port up 5° SEN are 60~120 mm at immersion depths from 100 to 140 mm. There are an upper and a lower recirculating zone for these two SENs at the vertical section through a port center. Dimension of these two recirculating flow zones varies with the immersion depth of the SENs. At 100 mm immersion depth of the tow SENs the eye of the upper recirculating flow is not evident. The eyes of the upper recirculating flows for 5-port up 5° SEN are close to the SEN, while the ones for 4-port down 5° SEN are close to the mold wall. On the liquid surface in the mold, flow produced with the 4-port SEN creates 8 recirculating flow zones close to the SEN, while 10 recirculating flow zones close to the mold wall are formed with the 5-port SEN.
Study on Formation Mechanism of Frame-Shaped Segregation in 40Cr Wire Rod Rolled from Bloom
Authors: Cheng Chang Gui , Liu Zhong Tian , Wan Wen Cheng , Zheng Yong Rui , Di Yong Tian
Published: December 2011

This paper has studied the formation mechanism of frame-shaped segregation in 40Cr wire rod rolled from bloom by means of the composition measurement, the electron microscopic observation and the energy spectrum analysis method. The results show that the frame-shaped segregation in wire rod originated from the positive segregation in columnar-to-equiaxed grain transition zone of bloom. The main influence factors are the solidification behavior of liquid steel in columnar-to-equiaxed grain transition zone, the temperature gradient of different solidification regions in bloom, the diffusion rate of the solute and inclusions in transition zone and so on. It may reduce the frame-shaped segregation by improving the purity of liquid steel, adopting the electromagnetic stirring in secondary cooling zone and enhancing the cooling intensity of the secondary cooling zone.
Acid Leaching of Vanadium from a Vanadium Residue
Authors: Li Xing Bin , Wei Chang , Deng Zhi Gan , Li Min Ting , Li Cun Xiong , Xu Hong Sheng
Published: December 2011

A process has been developed at the laboratory scale for leaching of vanadium from a vanadium residue using mixed hydrofluoric and sulfuric acid solutions, and NaClO as an oxidant. The extraction studies were carried out using various acid concentrations, liquid/solid ratios, addition of oxidant, reaction temperatures and leaching times. The optimum leaching conditions were then determined. Characterization of the leach residues was carried out by SEM and EDS analysis. Results indicate that the silicates can be effectively destroyed by HF, and the vanadium contained in the vanadium-iron spinel can be leached by the mixed acid solutions. The addition of NaClO enhanced the leaching process by the oxidation of V3+(s) to V4+ and V5+. The leaching efficiency was also improved by raising the leaching temperature, prolonging the reaction rime and using a higher liquid/solid ratio. A vanadium recovery of 81.8% was obtained by the direct acid leaching process
A Novel Method of Leaching Vanadium from Extracted Vanadium Residue Using Sodium Sub-Molten Salt Medium
Authors: Li Lan Jie , Zheng Shi Li , Chen Dong Hui , Wang Shao Na , Du Hao , Gao Ming Lei , Zhang Yi
Published: December 2011

Leaching of an extracted vanadium residue in sodium sub-molten salt medium was investigated. The significant effects of reaction temperature, particle size of residue, reaction time and NaOH-to-residue mass ratio on vanadium extraction were studied. By the orthogonal experiment study, it can be concluded that the impact order of factors is Tr> t>R according to the significance to the leaching process. Under conditions of reaction temperature 170°C, NaOH-to-residue 4:1, stirring speed 700 rpm, particle size -74 µm and reaction time around 180 min, leaching efficiency of vanadium obtained is higher than 90%. And, the leaching process of vanadium, with activation energy 27.69 kJ•mol-1, is controlled by the chemical reaction-controlled as the following rate equation. ln(1-x)=-kt
Microstructure Evolution of A356 Aluminum Alloy Produced by Cooling Slope Method
Authors: Nourouzi Salman , Ghavamodini Sayed Mahdi , Baseri Hamid , Kolahdooz Amin , Botkan Mohammad
Published: December 2011

In this work the cooling slope (CS) method was employed to produce the A356 feedstock in semisolid processing. The dendritic primary phase in the conventionally cast A356 alloy has transformed into a non-dendritic one in ingots cast over a cooling plate with (625°C, 650°C and 680°C) superheat. After pouring, the melt which became semisolid at the end of the plate was consequently poured into cylindrical steel mold with the various mold temperatures of (25°C, 200°C, 400°C). In this study, the cooling slope was adjusted at 50o with respect to the horizontal plane and 500mm length. It was found that the pouring and mold temperature affect the size and morphology of α-Al phase.
Research of Biological Desilication Mechanism by Bacillus mucilaginosus GSY
Authors: Hui Ming , Hou Yin Chen , Tian Qing , Shang Xiao Li , Zhang Kai Ping
Published: December 2011

Biological desilication by Bacillus mucilaginosus was investigated using 10 g/L of the cell suspension, fermented liquid and 100 μg/mL of polysaccharide solution. Results showed that the ratio (A/S) of Al and Si in bauxite increased from 2.84 to 3.32, 3.74, 4.19, respectively; and the effects of desilication were all significant by T test. The infrared spectra both of the cell and polysaccharides before and after leaching had significant changes at the wave number of 1070 cm-1 and there were two peaks broadened absorption after leaching, so these appear that the silicon complexes were formed by Si-O-R form. Before and after leaching of bauxite, it was observed by the scanning electron microscope, many holes were formed and the bacteria in the leaching process had significantly erosion on the bauxite surface. Otherwise XREDS analysis further proved that Bacillus mucilaginosus GSY had significant desilication effect.
Mechanism of Precipitate Removal of Antimony and Bismuth Impurities from Copper Electrolyte by Arsenic
Authors: Xiao Fa Xin , Mao Jian Wei , Cao Dao , Shen Xiao Ni
Published: December 2011

This paper investigates the mechanism of removal of Sb and Bi from copper electrolyte under the function of arsenic. The precipitation reactions were carried out from a synthetic electrolyte containing 185g/L sulfuric acid and 45g/LCu2+ in the presence of As (III, V), Sb(III, V) and Bi(III) under the temperature 65°C and stirring rate of 300r/min. The structure, morphology and component of the precipitate were clarified by methods of chemical analysis, SEM, XRD, TEM, EDAX and IR spectroscopy. A kind of white precipitate has irregular shape and mainly consists of As, Sb, Bi and O elements forms in this electrolyte. The characteristic bands in the IR spectra of the precipitate are O-H, As-OH, As-O-Sb, Sb-OY (Y=As, Sb, Bi), and O-As-O. The precipitate is a mixture of microcrystalline of (Sb,As)2O3, BiSb2O7, SbAsO4 and amorphous phases by XRD and electronic diffraction. The removal rate of Sb and Bi reaches 43% and 64%, respectively from copper electrolytes by a 4g/L arsenic solution owing to these precipitate.