bluuebunny/crossref_metadata_2025 huggingface dataset:
Microstructure Evolution in the Atomized Droplets of Mg-9wt%Al Alloy
Authors: Ding Fei , Wang Xiao Feng
Published: November 2010

A numerical model is developed to describe the kinetics of the microstructure evolution in an atomized droplet of Mg-9wt%Al alloy. The model is coupled with the heat transfer controlling equations to simulate the solidification process of the atomized droplets. The numerical results show that the microstructure development is a result of the common action of the nucleation and growth of grains. The nucleation events take place at a critical supercooling for a given droplet. As the droplet size decreases, the critical supercooling increases significantly. The volume fractions of the phases formed during the period of the recalescence, the segregated solidification and the eutectic reaction are sensitive to the droplet size. It is demonstrated that the developed model describes the microstructure evolution process well.
Friction and Wear Properties of SiC and Immerse the Copper Graphite Against 1Cr18Ni9Ti Friction Couples
Authors: Tian Xiao , Fang Li De , Zhu Yan
Published: November 2010

Friction and wear properties of SiC and immerse copper graphite(C/Cu) against stainless steel (1Cr18Ni9Ti) friction couples were studied under room temperature and unlubrication by pin-disc tribometer. The test shows that at sliding speed of 0.56ms-1 and normal load of 5N, 20N, the SiC/1Cr18Ni9Ti friction coefficient decreases. The immerse copper graphite shows good friction and wear behavior at load 50N, at which the copper of graphite matrix is transported to the surface from the pore of graphite matrix to form a couple of copper and copper. It is difficulties to measure volume loss. When load increased, the copper was transported to generate the film and was grinded away continuously, which the immerse copper graphite(C/Cu) volume loss increases at load 120N. The results of comparing two couples show volume loss of the couple SiC/1Cr18Ni9Ti is severe, so it is not suitable to combine a couple. The couple of immerse copper graphite (C/Cu)/1Cr18Ni9Ti is better applied at low load.
Simultaneous Observation of Nanocrystalline BaTiO3 Ceramics Surface Morphology and Ferroelectricity Using Scanning Nonlinear Dielectric Microscopy
Authors: Xiao Chang Jiang , Li Zheng Xin , Deng Xiang Rong
Published: November 2010

A scanning nonlinear dielectric microscopy (SNDM) with an additional electrically conducting atomic force microscope cantilever as a probe needle is adopted to simultaneously observe the surface topographic and domain images of nanocrystalline BaTiO3 ceramics with super-high resolution. The sample exhibits a uniform grain size distribution and the average grain sizes are calculated to be about 30 nm. Some regions are brighter than the others in SNDM image, indicating the existence of ferroelectric domains structure. In addition, P-E hysteresis and piezoresponse loops are found in nanocrystalline BaTiO3 ceramics. The experimental results demonstrate that the SNDM with the function of atomic force microscopy is very useful for understanding domain structures of nanocrystalline ferroelectric materials.
The Analysis of Pressure Capability of Different Teeth Structures in Ferrofluid Seal
Authors: Xing Fei Fei , Li De Cai , Yang Wen Ming
Published: November 2010

Theoretical model of calculating magnetic field of typical ferrofluid sealing structures with magnetic vector potential method is built. Based on the theoretical model, magnetic field distribution of rectangular teeth, two-sides dilated shape and one-side dilated shape teeth structures with common other conditions were calculated using finite element method when the sealing gap was 0.1mm and 0.12mm. The comparison of their results with the same sealing gap showed that one-side dilated shape teeth structure had higher pressure capability than other shape teeth under reasonable design.
Study on the Variation of the Properties with Increasing of Bending Cycles of Coiled Tubing
Authors: Bi Zong Yue , Xian Lin Yun , Jing Xiao Tian
Published: November 2010

The Variation of the mechanical properties of coiled tubing with increasing of the bending cycles was studied based on the fatigue bending cycle machine. The results show that the tensile strength had no significance changes during cycle fatigue. The yield strength and the force value was significantly decreased after 300 cycles, and the corresponding decreased magnitude linearly increased with the increasing of bending cycles. The changing tendency of strain hardening exponent on compression surface is different from the one on extruded surface. When the cycles increase from 100 to 600, the exponent on compression surface shows increases firstly, and decreases afterwards, However, the one on extruded surface shows decreases firstly, and increases afterwards. The yield strengths of the compression surface and extruded surface show the same changing tendency as strain hardening exponent.
Effects of Anions on Corrosion Behavior of Ni-Cu-P Coatings
Authors: Liu Chong Yang , Liu Gui Chang , Wang Sui Lin , Wang Li Da
Published: November 2010

Ni-Cu-P coating was synthesized on copper substrate by electroless plating technique. The coating composition and corrosion resistance of Ni-Cu-P coating were characterized using energy-dispersive X-ray (EDX), electron probe micro-analyzer (EPMA), polarization curve (PC) and electrochemical impedance spectrum (EIS). The results show that the chemical nature of anions plays very important roles in the corrosion behavior of Ni-Cu-P coating. At a higher electrolyte concentration, Cl- and SO4 2- ions tend to promote the dissolution rate of Ni by their adsorption, while at lower electrolyte concentrations, NO3 - ions tend to dominate the dissolution rate of Ni-Cu-P coating.
The Sustainable Capability Research on Copper- and Iron-Based Oxygen Carrier
Authors: Chen Lei , Jin Jing , Duan Hui Wei
Published: November 2010

Chemical-looping combustion (CLC) is a new kind of efficient method to separate CO2. At present, most of CLC research focuses on the development of oxygen carriers. The sustainable capability is the one of important standards to evaluate performance of oxygen carrier. The iron- based and copper- based oxygen carrier were chosen in this paper. The comparative study between the analytically pure oxygen carriers and the prepared oxygen carriers with Al2O3 were made according to the reactivity of reduction and oxidation. The data was obtained by the TGA, SEM and XRD. The results show that the prepared carriers with Al2O3 are greatly improved both in reaction ratio and sustainable capability, and Fe- based oxygen carrier is better than the Cu- based oxygen carrier in the sustainable capability.
Surface Modification of TA18 by Thermal Oxidation
Authors: Hu Jing , Wang Da Yue , Teng Xiao Wei , Wang Yan , Gao Xin Yan
Published: November 2010

TA18 alloy was used as the base material to investigate the effect of thermal oxidation (TO) on titanium alloys. The samples were subjected to TO treatment in a conventional muffle furnace at the same duration (210min) for different temperatures under air atmosphere. The results showed that an oxide layer comprised of rutile TiO2 and a small amount of Al2O3 were formed for samples thermally oxidized at 700°C and above, and both rutile and Al2O3 peaks increase with the treating temperature. The surface hardness increased significantly with the treating temperature due to the formation of a thin oxide layer and an oxygen diffusion zone in TO process. The wear test results showed that TO process can significantly improve the wear resistance, and the wear resistance is a function of the treating temperature, with 700°C being the optimum temperature to improve wear resistance of TA18 alloy for the duration of 210min.
The Research and Application of Methylene Blue Testing Method to Characterization of Powder Lot (or Fine Aggregate) in Asphalt Mixture
Authors: Yu Miao , Wu Guo Xiong
Published: November 2010

There is a comparison among the six Methylene Blue testing methods from different areas and institutes which respectively belong to China, U.S. and Britain. So as to improve the current MBV test of powdery lot used in asphalt mixture in China，it is found that current MBV test needs to be improved by analyzing powder lot Suspension、the concentration of Methylene Blue solution、stirring speed、powder lot types, temperature and soil content. So the revising suggestion to test method T0349-2005 included in standard JTG E42- 2005 is put forward. Later in the micro-surfacing test it is found that by adjusting the silt content, the water damage resistance and anti-abrasion abilities have been affected significantly which are good related to the MBV test recommended in this paper, so it is evident that the improved MBV test is crucial to the quality control over fine aggregates.
Study on the Law of High Temperature Oxidation under Tensile Force on Cr5Mo Alloy
Authors: Chen Shun Qing
Published: November 2010

Basic on a lot of tests, the process of high temperature oxidation under tensile load had been experimentally researched on Cr5Mo alloy. The surface crack and the reaction rates and the shell of high temperature oxidation under tensile load or without tensile load also had been analyzed on Cr5Mo alloy, then the exactly research law of high temperature oxidation under tensile load had been gotten on Cr5Mo alloy in this paper.
Back Pinch Roll Improvement of Slab Sizing Press
Authors: Li Jun Hui , Liu Cai
Published: November 2010

The problem that the pinch roll of the Slab Size Press was worn away partly appeared in some domestic steel mill so based on the DEFORM finite element software a pressing mode1 for Slab Sizing Press was established. After analyzing the deformation of dog bone by the modeling experiment finite element, a new kind of roll is brought forward. The contact condition between pinch roll and pressed slab is improved by it so that the use time of the pinch roll is extended.
Study on Multifractal of Recrystallized Microstructure for TB8 Alloy
Authors: Li Ping , Nie Ai Qin , Xue Ke Min
Published: November 2010

On the basis of MATLAB software，multi-fractal analysis program has been developed．Systematic fractal analysis of micrographs of TB8 alloy after hot compression deformation and solution treatment has been conducted．Corresponding probability measure and scale exponent from the microstructure images can be acquired and the multifractal spectra can be calculated．The results show that the microstructure of TB8 alloy after hot deformation and solution treatment has the characteristic of multi-fractal within the computing scale．And with increase of the recrystallized grain size and decrease of the deformed grain size，the width of the multi-fractal spectrum Δα decreases and the microstructure distribution is homogeneous．Furthermore，with increase of the recrystallization percent，the value between the maximum and minimum subset dimension Δf increases．It indicates that the recrystallized grains are the dominant factors in determining the size distribution in the microstructure and the grains are fine and uniform．These studies supply a new method for analyzing material microstructure quantitatively
Microstructural Morphology and Formation Mechanism of Rapidly Solidified Al-21Si Multi-Alloys
Authors: Wang Ai Qin , Xie Jing Pei , Wang Wen Yan , Li Ji Wen
Published: November 2010

In the present work, rapidly solidified Al-21Si-0.8Mg-1.5Cu-0.5Mn alloys strips was prepared by melt-spinning method. The microstructures, phase and morphology characteristics of the experimental alloy were characterized by means of scanning electron microscopy, transmission electric microscopy. The results show that the microstructures are changed obviously compared with conventional condition. The nucleation and growth of primary silicon are suppressed and primary silicon can not deposited, meanwhile, α-Al phase is nucleated which prior to eutectic. The microstructures of the rapidly solidified alloys are composed of primary micro-nanostructure α phase and feather-needles-like (α+Si) eutectic which set in the α phase. The mechanism of formation for microstructures of melt-spinning Al-Si alloy have also been discussed.
Sound Absorption Properties of Aluminum Sponges Manufactured by Infiltration Process
Authors: Fernández Patricia M. , Cruz Luis J.R. , García Cambronero Luis E. , Díaz Cesar , Navacerrada María Ángeles
Published: November 2010

In this paper, the sound absorption properties of aluminum sponges manufactured by infiltration process have been studied. The results show that the sound absorption factor α changes in function of pore size. Additionally, the sound absorption factor α was sensitive to the frequency range measured and it was depending of the thickness sample. It was found that the interconnected porosity plays an important role increasing the sound absorption properties of the aluminum sponges studied.
Theory and Experimental Research on Inclusion Modification in Improved Carbon Structural Steel
Authors: Zhang Cai Jun , Zhu Li Guang , Tu Dong Mei , Wang Shuo Ming , Ding Hui
Published: November 2010

By means of the thermodynamics analysis of inclusion modification in the process of calcium treatment, and the advantage area chart of calcium, aluminum, sulfur, oxygen activity in inclusion midification, this paper analyzes the effects of molten steel temperature, aluminum activity, sulfur activity and other factors on inclusion modification. After calcium treatment, inclusions in high-quality carbon steel S48 will become massive or globular calcium aluminate, MnS inclusion and the composite inclusions of MgO·Al2O3 in kernel and CaO·Al2O3 in shell.
Finite Element Simulation of Die Design for Equal Channel Angular Extrusion Process of Pure Aluminum and its Experimental Investigation
Authors: Xu Shu Bo , Jing Cai Nian , Ren Guo Cheng , Zhao Guo Qun
Published: November 2010

equal channel angular extrusion/Pressing (ECAE, ECAP) has the capability of producing ultra-fined grain (UFG) materials bellow the dimension of 1 μm. At present, it is one of the most important methods to get bulk UFG materials. In this paper, a systematic investigation of ECAP process on the pure Aluminum and die design is performed by using numerical simulation. The stress distributions on the die were obtained, and general consideration of the die during the whole pressing process was given. it was found that the closer the die corner is, the higher stress value results can be acquired. And the effective stress concentration in ECAP die cavity corner. The extruding load fell rapidly when the angular angle increasing. The proposed method can serve as preconditions to analyze the abrasion and fatigue of ECA Pressing die.
Preparation and Photoactivity of Titanium Dioxide-Coated Carbon Felt Using Supercritical Carbon Dioxide
Authors: Li You Ji , Chen Wei , Li Lei Yong , Ma Ming Yuan
Published: November 2010

TiO2–coated carbon felt (TCF) was prepared via a supercritical treatment with titanium tetraisopropoxide (TTIP) and different carbon felt as a precursor and support, respectively. The TCF samples with different carbon felts were characterized by X-ray diffraction, scanning electron microscopy, UV-VIS spectroscopy, particle size analyzer and BET surface area. The photocatalytic activities of samples were evaluated by congo red (CR) degradation. The result reveals that all the three samples show much higher photoactivity than the commercial P25. The activity order of the three samples is TCF1< TCF2 < TCF3. The photoactivity is strongly dependent on the surface area and the crystallite size: the larger the surface area and the smaller the crystallites, the higher the efficacy of photocatalytic degradation. The optimal photocatalytic condition is a CR concentration of 45 mg/l at pH 7.
In Situ Mg2Si Reinforced Mg Alloy Synthesized in Mg-SiO2 System
Authors: Huang Dan , Wang Yan Li , Wang Ying , Cui Hong Bao , Guo Xue Feng
Published: November 2010

The thermodynamic analysis in Mg-SiO2 system was conducted for the determination of the priority reaction at experimental temperature. Then, Mg2Si reinforced Mg alloy was synthesized through reaction in Mg-SiO2 system at 730°C, whose Si mass fraction is up to approximately 10%. The thermodynamic analysis and microstructure investigation results show, that generation of reinforcing phase of Mg2Si in Mg alloy from the reaction in Mg-SiO2 system is feasible with lower free energy than that in Mg-Si at the same temperature; and under the experimental temperature and solidification condition, the microstructure of Mg-10Si alloy is composed of coarse primary Mg2Si dendrite crystal, Chinese script type eutectic Mg2Si, and α–Mg phase, the formation of α–Mg holes is resulted from the relatively high cooling rate leading to a deviation from the equilibrium diagram during solidification.
Cellular Automaton Modeling of the Isothermal Hot Compression Phase Transformation in TA15 Titanium Alloy
Authors: Gan Guo Qiang , Xue Ke Min , Li Ping
Published: November 2010

A two-dimensional cellular automaton model is developed to simulate the isothermal hot compression phase transformation of β→α in TA15 titanium alloy. The model, based on the data of hot compression deformation and some assumption, the phase transformation nucleation and growth function of the phase β→α which is utilized by the automaton in a probabilistic fashion. The probability of nucleation and growth of α phase is confirmed and described by the existing theories of dislocation density. The competition between phase transformation and growth of transitional phase is described by the changes of dislocation density in this cellular automaton lattice. Based on the results of cellular automaton, the transformation fraction of α phase is calculated with the number of lattice and isothermal phase transformation kinetic equation is also calculated with data of transformation fraction, and the effect of hot compression deformation parameters on phase transformation is also discussed.
Influence of Solution Conditions on Aging Response of Ti-3.5Al-5Mo-4V-2Cr-1Fe-2Zr-2Sn Titanium Alloy
Authors: Ge Peng
Published: November 2010

Ti-3.5Al-5Mo-4V-2Cr-1Fe-2Zr-2Sn titanium alloy is a new high strength metastable beta titanium alloy which was designed according to the principle of ‘near critical molybdenum equivalent and multicomponent strengthening’. The effect of solution treatment on aging responses of the new alloy including room temperature tensile properties and microstructures were investigated. There is a tendency that the tensile strength is increasing with the increase of solution temperatures on the same aging conditions and water quenching from solution temperatures can produce higher age hardening effect than that treated by air cooling. The results revealed that the specific aging response of the new alloy is from the high driving force of phase precipitation together with the effect of excess vacancies.
The Effect of Ti-Zr Deoxidation on the Mechanical Properties of High Strength Low Alloy Steels
Authors: Lu Wei Yu , Meng Ling Dong , Wang Hong Hong , Wang Dao Yuan , Yao Yong Kuan , Wu Kai Ming
Published: November 2010

The uniformity of the mechanical properties, especially elongation and impact toughness, were compared between steel A, which was deoxidized with Ti-Zr, and steel B, which was deoxidized with Al. Microstructural observations, energy dispersive X-ray spectroscopy and X-ray diffraction analyses were conducted using an optical microscope, a scanning electron microscope and a transmission electron microscope, respectively. Results showed that sub-micron and nano-sized complex oxides were obtained by the combined deoxidation of Ti-Zr. The stability of the mechanical properties of steel A was better than that of steel B. The elongation and impact toughness of steel A were enhanced relative to those of steel B. This was attributed to spheroidization and the dispersed distribution of MnS inclusions in the matrix of steel A.
Experimental Study on Fundamental Characteristic of Recycled Concrete
Authors: Xu Yuan , Wang Ru Heng , Yao Hua Chuan
Published: November 2010

First, the fundamental characteristic of recycled concrete aggregate wasstudied. Then, the recycled concrete spiciemen with different maximum size was tested. The results showed that: the apparent density and bulk density of recycled concrete aggregates was smaller than the natural rock, but the moisture content, crushed index, water absorption was higher. The workability of recycled concrete improved with increase of water and fly ash, but its strength decreased as the increase of water and fly ash. The research on performance and strength of recycled concrete aggregate will provide certain theoretical basis in the application process.
Temperature Coefficient of Resistance (TCR) Measurement Method to Evaluate Metal Process of CMOS Technology
Authors: Wahab M.Z. Abdul , Mamat H. , Jalar A.
Published: November 2010

Temperature Coefficient of Resistance (TCR) is the important parameter in Electromigration Test of the metal reliability. The physical dimensions of the metallization can be affected by temperature. The coefficient of thermal expansion for a sample of the metallization can be used to approximate its change in volume given and a change in temperature. An object of uniform cross section will have a resistance proportional to its length and inversely proportional to its cross-sectional area, and proportional to the resistivity of the material. TCR is a fractional change in resistance per unit change in temperature at a specified temperature. In order to get the most reliable metal lines, lower TCR value is needed. Normally lower TCR value can be obtained if the grain size of the metal line is smaller. In this study, two types of metal process flows which are known as hot and cold metal is evaluated using TCR measurement. The hot and cold metal process use the same source of AlSiCu but the preparation for deposition is a bit different in which the hot metal process used temperature setting of 300oC, while the cold metal process the temperature is set at 175oC. From the result it is found that the metallization sheet resistance is linearly increase with increasing temperature and the TCR value also decrease with smaller line widths. From the FIB micrograph picture it is found that lower process temperature will give smaller grain size and lower TCR value.
Comparison of Two Different Chemical Conversion Coating on Aluminum Alloy
Authors: Wu Yan Bo , Zeng Si Si , Sun Peng
Published: November 2010

In this paper, we made two different chemical conversion coatings on aluminum alloy by TiOSO4 and Na2WO4. The morphology of the chemical conversion surface layers were observed by scanning electron microscopy (SEM). The microcosmic phase structures were characterized using X-ray diffraction (XRD). Electrochemical method was used to study the coatings corrosion resistance. The results indicated that the two conversion coatings were crystal structure material, the surface of coating were both show pothole structure. TiOSO4 coating have better corrosion resistance than Na2WO4 coating.
Study on Property of Ti-Based Nonevoparobal Getter
Authors: Li Teng Fei , Zhang Yan , Wei Xiu Ying , Yuan Peng , Mao Chang Hui
Published: November 2010

The getters composed with Titanium and Zr-V-Fe were prepared by conventional powder metallurgical technology. The sorption properties and mechanical strength of the Ti-Zr-V-Fe getter prepared with three different average particle sizes of Titanium powder were investigated. The results showed that the smaller Titanium powders particle size can effectively improve the property of the nonevoparobal getter, but if particle size is too small, the sorption of the getter will decrease. The getter which was added with Titanium powder of 48μm has the best hydrogen sorption capability. With the decrease of the size of Titanium powder, mechanical strength will be improved remarkably. In the paper, the sorption characteristics for different gases were analyzed initially and the understanding for Zr-based getter is more extensive. The results show that the getters can adsorb activated gases, such as H2, N2 and CO. The pumping speed for H2 is best than that for N2 and CO.
Effects of Sm on Microstructure and Mechanical Properties of Mg-5.5Al -0.5Y Alloy
Authors: Li Chang Qing , Li Quan An , Zhang Xing Yuan , Zhang Qing
Published: November 2010

The microstructure and mechanical properties of aged Mg-5.5Al-0.5Y magnesium alloy with Sm addition were investigated. The results show that with proper content of Sm addition, the microstructure of Mg-5.5Al-0.5Y magnesium alloy is refined obviously. The quantity of β-Mg17Al12 phase is reduced, and Al2Sm particle phase is formed. With the increase of Sm addition, the mechanical properties of the alloy at room and elevated temperature increase at first, and then decrease. When the content of Sm is up to 1%, the values of tensile strength and elongation at room temperature,150 and 175 are up to their maxima synchronously, 244MPa/20.07%, 217MPa/18.86% and 185MPa/19.15% respectively.
Comprehensive Analysis of High Nitrogen Steel Refining Factors with High-Pressure and Bottom-Blowing Nitrogen
Authors: Jin Gang Qiang , Wang Shu Huan , Guo Yu Feng , Liu Xin Sheng
Published: November 2010

The experimental results on high nitrogen steels refining with high-pressure and bottom-blowing nitrogen were analyzed by the theories of thermodynamics and kinetics in high nitrogen steels smelting. It was shown that nitrogen content in steel increases with the increase of the following factors, that is, pressure, alloying elements (Cr and Mn), bottom-blowing time and bottom-blowing flow. While the nitrogen content in steel decreases with the temperature increase, but it is not obvious. The nitrogen content in steel can also increase with the surface active elements (O and S) decreasing.
Development of Piston Salt Core for the High Duty Engines
Authors: Liu Shi Ying , Tian Xiao Qing , Zhao Xu Dong , Feng Zeng Jian
Published: November 2010

New salt core technique for using in the high duty internal combustion engine piston under high pressure cast was developed.With special additional ceramic, the salt core’s compressive strength and the density performance were improved. Granulation technique could refine the grain microstructure. Orthogonal experiments were adopted for getting the process parameters, in this way, oil cooling gallery can be formed completely by the new technology. The new progress has been widely used by the high duty pistons.
Large Deformation Analysis of Hyperelastic Membranes Containing a Hole or Inclusion
Authors: Wang Wen Jia , Liu Bo , Sang Jian Bing , Lu Chen Hua
Published: November 2010

A large deformation analysis has been given by using a modified Gao’s second constitutive relation. In certain circumstances, the new constitutive relation may be simplified to the Mooney-Rivlin and Neo-Hookean models. With regard to incompressible materials, when the influence of the second strain invariant is neglected, the modified model brings a unified form of Gao’s two constitutive models. The new constitutive relation has been utilized to resolve a problem of a hyperelastic membrane containing a hole or rigid inclusion. The basic governing equations of incompressible materials have been obtained and numerical solutions of equations illustrate how constitutive parameters affect the result of membranes’ deformation. These conclusions may provide helps to practical problems.
Microstructure Evolution of Directionally Solidified Al-Cu Alloys
Authors: Qu Min , Liu Lin , Zhao Ming , Liu Feng Bin , He Guang Ping
Published: November 2010

The microstructure evolution of Al-Cu alloys with different compositions is investigated in directional solidification. Two distinctly different microstructure evolution mechanisms are obtained in Al-0.85%Cu and Al-4%Cu systems, respectively. In Al-0.85%Cu alloy, it shows a peculiar phenomenon, the microstructure evolution is always cells and no dendrites are obtained. In other words, the cells undergo several transitions as the pulling velocity increasing from 15μm/s to 300μm/s, they follow the sequences: mixed microstructure of pox and banded cells →mixed microstructure of polygonal and banded cells →banded cells →elongated cells. Particularly, it is studied what caused the dendrites not appear in Al-0.85%Cu system. Finally, it comes to the conclusion that there are two aspects which lead to the phenomenon: a dilute alloy composition and a relatively higher temperature gradient.
Microstructural Evolution and Mechanical Properties of AZ91 and SiCp/AZ91 Magnesium Alloys upon Rapid Solidification/Powder Metallurgy Followed by Hot Extrusion
Authors: Yu Hui , Yu Hua Shun , Zhang Zhen Ya , Min Guang Hui , Chen Cheng
Published: November 2010

In this study, AZ91 and SiC particulates reinforced AZ91 (SiCp/AZ91) magnesium alloys were successfully fabricated using rapid solidification/powder metallurgy technique followed by hot extrusion. Microstructural evolution and mechanical properties of the monolithic AZ91 and SiCp/AZ91 magnesium alloys were evaluated. SiC particulates were well distributed with only few agglomerated particles. The porosity level and microhardness increased as SiCp content increased because the increased surface area of SiCp, harder ceramic phases and SiCp acted obstacles to the motion of dislocations. In addition, an increase in particulate reinforcement content was observed to decrease mechanical properties of the composite compared with the unreinforced counterpart due to increasing agglomerating regions and porosity, brittle interface debonding between matrix and SiCp.
The Effect of Carbon on the Curie Temperature of κ Phase
Authors: Chang H. , Jean Ming Der , Gan D. , Kao P.W.
Published: November 2010

The effect of composition on the Curie temperature of κ phase Fe3AlCx was investigated by thermomagnetometry analysis (TMA). Results reveal that increasing carbon content decreases the Curie temperature. Serrations in the magnetization vs. temperature curve in the Fe3AlCx found at about 100°C, may arise from the fluctuation of carbon atoms between Site I and II of κ phase unit cell.
Research on the CNC Machining Simulation Model Build and Realize Based on the Spiral Bevel Gear with Forming Method
Authors: Hu De Ji , Meng Qing Guo , Zhao Wei
Published: November 2010

In view of the spiral bevel gear machined by the semi-generating means, a new method to create 3D solid model is proposed. The equation of tooth profile surface is deduced from the principles of spiral bevel gear engagement and cutting, according to the position relationship of the machine tool, the cutting tool and the workpiece, along with the cutting tooth process. Then the three-dimensional solid model of spiral bevel gear is developed with the delphi program using the known parameters and the above mathematic equations. The effectiveness of this method has been demonstrated.
Forming Limit of Holed Dome in Two-Stage Stretch Forming
Authors: Hirahara Atsushi , Hino Ryutaro , Yoshida Fusahito
Published: November 2010

This paper deals with the accurate prediction of forming limit of a dome with a circular hole in two-stage stretch forming. Since this two-stage forming is a process of non-proportional deformation, a fracture criterion, which is capable to predict fracture limit of sheet metal under non-proportional strain path, is introduced. The limit dome height of steel blank is predicted by utilizing numerical optimization technique, in which the fracture criterion is used as a constraint function to avoid sheet breakage. The calculated result and the corresponding experimental result show that the fracture criterion can successfully predict the limit dome height in the two-stage forming while the classical forming limit diagram (FLD) overestimates it.
Comparative Study on Tribological Behaviour between AZ71E and AZ91D Alloys under Ambient and Elevated Temperature
Authors: Huang Wei Jiu , Yao Miao , Zhang Xiao Bin , Huang Lin Lin
Published: November 2010

The tribological properties of AZ71E and AZ91D magnesium alloys were comparatively investigated at ambient and elevated temperature. The results indicated that the wear rates of both alloys increased with increasing load, whereas the friction coefficients decreased with increasing load. The wear resistance of AZ71E alloy was significantly superior to that of AZ91D at higher loads and elevated temperature. At ambient temperature, abrasive wear is the predominant wear mechanism for AZ71E, whereas the wear mechanism for AZ91D transfers from abrasive wear to delaminative wear. At elevated temperature, the predominant wear mechanism of both alloys changed from mild wear regime to severe wear regime.
Textures in Multi-Directional Forged Mg by Neutron Diffraction
Authors: Gan Wei Min , Brokmeier Heinz Guenter , Zheng Ming Yi , Wu Kun
Published: November 2010

Texture evolution in the MDF processed ZK60 along forging axis was investigated by advanced neutron diffraction. Texture analysis was related to the deformation mechanism. Results showed that basal planes deformation was dominated and accommodated by non-basal and twinning. Gradient texture indicated an inhomogeneous distribution of imposed strains along forging direction. This could be related to the non-precise MDF processing.
The Cause Analysis of Pseudo Solder in Surface Mounted Technology
Authors: Wu Fu Pei , Li Sheng Ping
Published: November 2010

Pseudo solder is one kind of familiar solder joint defect, and it is very difficult to be detected in surface mounted technology. Reduce the pseudo solder is viewed as one of effectively way to keep the quality of solder joints. In this manuscript, the quality of component, solder paste printing process, mounting processing, reflowing process, solder material are analyzed to illustrate the cause of pseudo solder in surface mounted technology. Based on the five factors, a pseudo solder model is built for IC component. In the pseudo solder model, its parameters are used corresponding to the cause of pseudo solder, and their values are used to evaluate the degree of satisfaction based on the SMT technological process. Experiments results show that parameters of the pseudo solder model can illustrate the cause of pseudo solder effectively.
Development of Low Carbon Bainitic Cr-B Steel with High Strength and Good Toughness
Authors: Huo Xiang Dong , Lin Zhang Guo , Zhao Yu Tao , Li Yu Qian
Published: November 2010

In order to develop low carbon bainitic Cr-B steel, experimental procedures including melting, thermal simulation study and laboratory hot rolling were adopted. The dynamic CCT diagram was established, microstructure and properties of experimental steel were also analyzed. The transformation temperature of experimental steel lies between 650～400°C and final microstructure changes fromquasi-polygonal ferrite, granular bainite to lath bainite as cooling rate increases from 0.2 to 50°C.s-1. The microstructure of steel plates, air cooled or water cooled to 530°C then air cooled, is mainly composed of granular bainite and quasi-polygonal ferrite, and the large size islands in granular bainite are responsible for the low strength and poor toughness. However, steel plate with lath bainite, water cooled to roomtemperature, boasts high yield strength (672MPa) and superior impact toughness (127J at -20°C). Therefore, it is feasible to produce low carbon bainitic Cr-B steel with high strength and good toughness through controlling cooling parameters.
Indentation Behavior of Aluminum Alloy with Inclusions
Authors: Zhao Bin , Zhang Yi Shang , Yue Zhu Feng
Published: November 2010

In this paper Finite Element Method (FEM) was used to study the indentation behavior of aluminum alloy 2A12 with nonmetallic inclusions. Indentation elastic-plastic tests and indentation creep tests were simulated with a cylindrical indenter to analyze the influence of the inclusion size and the inclusion depth. FEM results indicate that the existence of inclusions will have certain influence on the indentation behavior, and when the inclusion size is close to the indenter size, the influence is obvious. For the indentation method, the conclusions can provide some useful information in the project application.
The Effect of Filler ER4043 and ER5356 on Porosity Distribution of Welded AA6061 Aluminum Alloy
Authors: Nur Azida Che Lah , Ibrahim Muhammad Faizol Ahmad , Jalar Azman , Sharif J. , Othman Norinsan Kamil , Rashdi Nasrizal Mohd
Published: November 2010

The filler metal used during welding process is believed to play an important role on porosity formation in aluminium alloy welded. The present investigation is aimed to study the effect of different fillers ER4043 (Al-5%Si) and ER5356 (Al-5%Mg) on porosity formation of AA6061 alloy welded joints. Butt-joint welds were made on 6 mm thick plates using 21 – 22 V arc voltages by using Gas Metal Arc Welding process (GMAW). The hardness profile of each types of AA6061 welded joints for both fillers were characterized by the Vickers microhardness test. In order to study the formation and distribution of porosity, the images of analysis were obtained using the X- ray CT-Scan. It was observed that, more porosities were found in the alloy AA6061 using ER4043 compared to ER5356 filler metals with the percentage area value of porosity about 18.3 and 8.4%, respectively. The hardness profile of ER5356 and ER4043 welded materials exhibited the similar hardness pattern profile. It is proposed that Si and Mg contents in the filler metal could play significant role in the distribution of porosity. No significant effect was observed on the hardness profile for both filler metals of welded materials.
Synthesis and Characterization of Fibular PANI/Nano-CeO2 Composites
Authors: Xu Hui , Chen Yong , Shi Xing Wei , Liu Xiao Yu , Gou Guo Jun
Published: November 2010

The fibular PANI/ nano-CeO2 composites were synthesized via chemical oxidation of aniline using nano-CeO2 as an oxidant, and nano-CeO2 was prepared by hydrothermal treatment. Sphere-like morphology and fibers of PANI/ nano-CeO2 composites were obtained. The resulting composites were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared (FT-IR). The results showed that chemical bonds existed between two phases. The acid concentration and nano-CeO2 particles affected the crystallinity of PANI fibers. The morphology of PANI was formed from the ball gradually developing into the fibular with rising of acid concentration. The regular crystalline structure of fibular was easy to form with a reducing CeO2 particle size.
Influence of Carbon Nanotubes on the Performances of LiFePO4
Authors: Feng Li Ming , Gai Teng , Wei Xue
Published: November 2010

To improve the performances of LiFePO4, a positive material in lithium battery, research on the influence of doping amount and doping form of carbon nanotubes (CNTS) on electrical resistivity, specific capacity, specific surface area and particle size distribution of LiFePO4 powder was conducted. The results indicated that, addition of CNTS significantly reduced the electrical resistivity no matter in pure LiFePO4 or LiFe0.98Mg0.02PO4; with same usage, coating of CNTS as carbon source performed better than mechanical grinding and mixing with LiFePO4. With the increase of CNTS content, a rising trend of both specific surface area (BET) and particle size (D50) in LiFePO4 powder was observed, but seeing a slight drop in discharge capacity under the rates of 0.2C and 0.5C. When the content of CNTS reached 3% (by mass) respectively through mechanical mixing and being added as carbon source, electrical resistivity of pure LiFePO4 dropped from over 105Ω•cm to 1868Ω•cm and 27Ω•cm accordingly, and that of LiFe0.98Mg0.02PO4 dropped from over 105Ω•cm to 4800Ω•cm.
The Microwave-Assisted Preparation and Properties of SiO2 Aerogels by Fractional Modification
Authors: Zheng Wen Zhi , Chen Li , Huang Xiang Hua , Fu Lei
Published: November 2010

Under microwave radiation and using trimethyl chlorosilane as modifier, hydrophobic SiO2 aerogel was prepared through fractional hydrophobic modification and ambient pressure drying of the raw material, tetraethoxysilane (TEOS), in the process of sol-gel and acid-base catalysis. Hydrophilic SiO2 aerogels were also prepared using the microwave method and water bath heating method. The SiO2 aerogels prepared using the three methods, including their morphology and chemical composition, were analyzed and compared using scanning electron microscopy, Brunauer-Emmett-Teller analysis method, Fourier transform infrared spectroscopy, X-ray diffraction, and themogravimetric-differential scanning calorimetry. The results indicate that by adopting the microwave reaction, the specific surface area of the SiO2 aerogels was effectively increased and the structure of the internal nanoscale pores of petal-coated shape was found to exist under the dense external surface of the SiO2 aerogels. Thermal stability of the hydrophobic SiO2 aerogels prepared through fractional modification assisted by the microwave method was increased with the hydrophobic angle at153°, which showed super hydrophobicity.
Autothermal Gelation Synthesis of Uniform Titania Nanoparticles
Authors: Wang Xi Xin , Zhao Jian Ling , Meng Zhao Hui , Yan Jia Wei
Published: November 2010

Titania nanoparticles were successfully synthesized through an easily controlled and simple autothermal gelation process. Effects of H2O2 concentrations, solvent quantity and dissolving temperature were investigated in detail. DSC–TGA and XRD analysis showed that the synthesized TiO2 nanoparticles were in anatase phase at 400°C and in rutile phase at 650°C. TEM image indicated that the titania nanoparticles were uniform and approximately spherical, the average grain size of the product was about 20 nm.
Molecularly Imprinted Polymer Microspheres Prepared by Precipitation Polymerization for Atenolol Recognition
Authors: Yu Jin Yang , Hu Xiao Ling , Song Ren Yuan , Xi Shan
Published: November 2010

Molecularly imprinted polymer microspheres for selective binding and recognition of atenolol were prepared by means of precipitation polymerization method using methacylic acid as functional monomer and trimethylolpropane trimethacrylate as cross-linker in the presence of atenolol as template molecule in acetonitrile solution. Computer simulation was employed to demonstrate the mechanism of the interaction between methacylic acid and atenolol. The scanning electron microscopy exhibited that the polymers were uniform spheres with the diameter of about 0.6µm. The adsorption properties of atenolol for imprinted microspheres were evaluated by equilibrium rebinding experiments. Scatchard plot analysis revealed that there were two classes of binding sites in the imprinted microspheres. The dissociation constant and the apparent maximum binding capacity were 4.56×10-4mol/L and 186.46μmol/g for the high affinity binding sites, 2.40×10-2mol/L and 4.01mmol/g for the low affinity binding sites. Compared to the structrally analogues, the imprinted microspheres exhibited a high selective reconizable capacity towards the template.
The Hamilton-Type Variational Principle of Electro-Magneto-Thermo-Elasticity
Authors: Song Hai Yan , Liu Zong Min
Published: November 2010

The basic equations of electro-magneto-thermo-elasticity are very complicated. It is hard to obtain analytical solutions, even if the simplest conditions were considered. The approximate method is an effective method to solve the complicate problems. However, the variational principle is theoretical foundation of finite element method and other approximate methods. According to the corresponding relations between generalized forces and generalized displacements, the basic equations of electro-magneto-thermo-elasticity are multiplied by corresponding virtual quantities, then integrated with volume and area, then algebraically added, and integrated with time, the Hamilton-type variational principles of electro-magneto-thermo-elasto-dynamics are established. They are the theoretical foundation of approximate calculation for multi-physics fields problem of electro-magneto-thermo-elasticity-dynamics.
Drug Release Behaviors of a pH/Temperature Sensitive Hydrogel Bead with Core-Shelled Structure
Authors: Deng Kui Lin , Dong Li Rong , Shi Yu E , Gou Yu Bo , Li Qian , Wang Shu Liang
Published: November 2010

As a drug delivery carrier, a novel pH/temperature sensitive bead (pTSB) with core-shelled structure from poly(N-acryloylglycine) (PAG), copoly(N-acryloylglycine methyl este and N-acryloylglycine ethyl ester) was prepared by two steps. In pH=7.4 phosphate buffer solution (PBS), the cumulative release amount of indomethacin loaded in the pTSB was about 60.1 % within 500 mins, but this value only reached to 22.3 % in pH=2.1 PBS. The release behaviors of indomethacin from pTSB also exhibited a remarkable dependence on PAG content in the core. Additionally, the release rate of indomethacin was much faster at 18 oC than that at 37 oC due to the temperature sensitivity of poly(N-acryloylglycinates). The experimental results indicate that pTSB seems to have a potential application in the drug release system controlled via pH or temperature in the biomedical fields.
A pH/Temperature-Sensitive Semi-IPN Bead for Drug Release Carrier
Authors: Deng Kui Lin , Gou Yu Bo , Zuo Jian , Dong Li Rong , Li Qian , Gao Ting
Published: November 2010

A series of pH/temperature sensitive hydrogel beads with semi-interpenetrating polymer network (semi-IPN), composed of sodium alginate and poly(N-acryloylglycinate) were prepared as drug delivery carrier. In pH=2.3 phosphate buffer solution (PBS), the release amount of indomethacin incorporated into the beads was about 9% within 610 min, while this value approached to 68% in pH=7.4 PBS. The release rate of indomethacin was higher at 37 than that at 20 . In addition, the release amount of indomethacin was increased with increasing poly(N-acryloylglycinate) content. These results suggest that the stimuli-sensitive beads have the potential to be used as an effective pH/temperature delivery system in bio-medical fields.
The Piston Orthogonal DOE Optimization Based on Multidisciplinary
Authors: Qu Xiang , Zhang Jun , Wang Wei , Jia Qiu Hong
Published: November 2010

A searching strategy of Multidisciplinary Design Optimization (MDO) which is based on Orthogonal Design of Experiments is put forward. Through the optimization, the quality of piston decreased 4.6%. The stress by coupling thermal load and mechanical load was computed. The result shows that the mechanical load, which is affected mostly by height of fire field, is the major stress.
Effect of Bi1.5ZnNb1.5O7 Nanopowder on its Ceramic Properties
Authors: Wang Xiao , Yang Liu Shuan , Huang Jin Liang , Li Fei Long
Published: November 2010

The Bi1.5ZnNb1.5O7 ( -BZN) ceramics were prepared by combining conventional solid synthesis (CS) and hydrothermal method (HTM). The emphasis was placed on the effects of doping nanopowder synthesized by HTM on the properties of -BZN ceramics. The results show that there is no effect of doping nanopowder on the sintering temperature and phase of -BZN ceramics. Therefore, with the increase of doping nanopowder, the density of ceramics decreases. Doped 10 wt% nanopowder, the ceramic sample sintered at 1000°C exhibits a well-crystalline phase and more excellent dielectric properties than others. At 1MHz, the observed value is about 148 and tan value is less than 3.365×10-4.
Preparation of Fluorine Doped TiO2 Photocatalysts and its Photocatalytic Activities under Simulate Sun's Rays
Authors: Gu Xing Yong , Li Can Ran , Hu Xiao Hong
Published: November 2010

F-doped TiO2 catalysts were obtained by sol process，in which tetrabutyl titanate was used as precursor and hydrofluoric acid as iondonors. The photodegradation experimental results showed that photoeatalytic activity of the F-doped catalyst is higher than that of the un-doped ones，the F-doped catalyst with 1:4(F:Ti molar ratio) fluorine at 40 was the highest catalytic efficiency under simulant sun's rays irradiation. The doped catalysts in anatase phase own higher photocatalysis characterized by XRD and BET. Effects of properties on the F-doped TiO2 catalysts were developed.