bluuebunny/crossref_metadata_2025 huggingface dataset:
The Competitive Reactions in Atomic Layer Deposition of HfO2, ZrO2 and Al2O3 on Hydroxylated Si(100) Surfaces: A Density Functional Theory Study
Authors: Ren Jie , Zhou Guang Fen
Published: February 2011

The competitive reactions in atomic layer deposition (ALD) of HfO2, ZrO2 and Al2O3 on the hydroxylated Si(100) surfaces are investigated by using density functional theory. The surface reactions in ALD of HfO2 and ZrO2 show large similarities in energetics and geometrical structures. However, both of them show discrepancies with the surface reactions in ALD of Al2O3. In addition, by comparing with the self-termination reactions, we could find that the further growth reactions are both kinetically and thermodynamically more favorable in ALD of HfO2, ZrO2 and Al2O3.
Improvement in Wear and Corrosive Wear Resistance of Ti6Al4V Alloy by Double Glow Plasma Surface Alloying with W-Mo and W-Mo-N
Authors: Tang Chang Bin , Liu Dao Xin , Li Fan Qiao , Tang Bin , Qin Lin
Published: February 2011

W-Mo and W-Mo-N surface-modified layers on Ti6Al4V alloy were obtained using a double glow plasma surface alloying technique. The morphology, microstructure, and chemical composition distribution of the modified layers were analyzed by scanning electron microscope, Xray diffraction, and glow discharge optical emission spectrometry. The hardness and toughness of the modified layers were measured using a micro-hardness tester, and dynamic repeating press equipment. The wear resistance in ambient air and the corrosive wear resistance in NaCl solution were evaluated using a ball-on-disk wear tester. The results show that W-Mo and W-Mo-N surface modified layers are composed of the alloying layers which vary in composition and phase form along the depth. A microhardness gradient was observed in the modified-surface layers. The surface hardness of the W-Mo-N and W-Mo modified layers was 25.3 and 14.2 GPa, which is seven-fold and 3.9-fold harder than the Ti6Al4V substrate, respectively. W-Mo and W-Mo-N surface-modified layers significantly improved the wear and corrosion resistance of Ti6Al4V. It seems that the wear resistance of W-Mo and W-Mo-N surface-modified layers in NaCl solution is better than that in ambient air owing to the strong lubricating effect of NaCl solution and the excellent corrosion resistance of the modified layers.
Rapid Synthesis of Molybdenum Disilicide by High-Energy Ball Milling
Authors: Feng Pei Zhong , Wang Xiao Hong , Liu Wei Sheng , Niu Ji Nan , Wu Jie , Zhang Shuai , Qiang Ying Huai
Published: February 2011

The product formation of Mo-66.7at.%Si powders mixture during mechanical alloying using a high-energy vibratory type ball-milling machine was investigated by X-ray diffractometer (XRD). The temperature of the vial was measured at intervals during ball milling. The results showed that some MoSi2 was formed by the mechanically induced self-propagating reaction during a milling time of 105~110min; at the same time the surface temperature of the vial is increased. In early stages of milling, as a result of extensive fracturing and cold welding of powder particles, the interfacial energy between Mo and Si powders and cold deformation energy led to the formation of supersaturated solid solution of Mo(Si). And then mechanically induced self-propagating reaction of MoSi2 occurred immediately. After this, MoSi2 was gradually synthesized by diffusion. MoSi2 andMo(Si) were the end products, and the end products underwent the amorphous trend.
Effects of Negative Bias Pulse on Characteristics of a-C:H Films Prepared by Plasma-Based Ion Implantation
Authors: Wang Yu Jiang , Ma Xin Xin , Tang Guang Ze , Sun Ming Ren , Xu Bin Shi
Published: February 2011

A series of a-C:H films have been prepared by plasma-based ion implantation (PBII) with acetylene on AISI 321 substrates. The effect of negative bias pulse on the characteristics of these films was investigated. The structures of the films were analyzed by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The surface hardness was measured by microindentation tests. The results indicated that the characteristics of these films are strongly depended on the negative bias pulse. When the bias pulse ranges from -10kV to -40kV, the films are typical diamond like carbon (DLC) films, while the films deposited at -5kV are polymer films. The peak intensity ratio of the D-band to that of the G-band (ID/IG) of the DLC films changes with the negative bias pulse. The minimum value of ID/IG (1.02) was gotten at -10kV.
The Surface Coating of YAG:Ce Phosphors with ZnO Nanoparticles for White LED
Authors: Chao Ke Fu , Xiao Zhi Guo , Zhang Hong Wei , Niu Wen Bin , Xia Wei , Sang Shi Yun , Xin Yi , Li Qi , Wu Su Li , Zhang Shu Fen
Published: February 2011

In this work, YAG: Ce phosphors coated with ZnO nanoparticles were prepared based on the wet chemical method in ethanol solution at low temperature. The surface character was characterized by XPS and SEM. The XPS spectra showed that the peak positions corresponding to the Zn 2p3/2 , Zn 2p1/2 and O 1s are 1022.08 eV, 1044.88 eV and 530. 8 eV, respectively. The SEM images showed that the surface of YAG:Ce were coated with ZnO nanoparticles. The thickness is about 25 nm. The luminescence properties of YAG:Ce phosphors coated with ZnO nanoparticles were studied. It is found that the photoluminescence intensity of coated phoshors increases a maximum at 12% compared with that of the uncoaed YAG: Ce phosphors and the enhancement of photoluminescence intensity depends on the consistency of ZnO nanoparticles. Finally, the YAG: Ce phosphors coated with ZnO nanoparticles were used for LED package. The results show that the luminescent intensity increases 6.8 % and the quantity of phosphors decreases 1 %. It is important for the lighting product to improve the luminescence intensity of white LED and decrease the cost of package.
Preparation of P-Type Microcrystal Si:H Films by ECR-PECVD
Authors: Zhang Xue Yu , Wu Ai Min , Yue Hong Yun , Hu Ju An , Wen Li Shi
Published: February 2011

P-type microcrystalline silicon films prepared by electron cyclotron resonance（ECR）PECVD are studied here. Silane diluted with Ar (SiH4/Ar=1/19) is used as a source gas and diborane (B2H6) diluted with H2 (100ppm) as doping gases. The effect of flow rate of doping gas on the microstructures and electrical properties of the films were investigated. Raman spectroscopy and X-ray diffraction were used to determine the film structure; AFM was employed to characterize the film surface topography; Hall measurements were carried out on the doped films to determine the carrier type, carrier concentration, and Hall mobility. The optical quality was measure by transmission spectrum.
Study on WC-Ni60 Complex Coating by High Frequency Induction Cladding
Authors: Wei Xin , Wang Gui Qin , Chang Yong Feng , Liu Chao
Published: February 2011

In this paper, WC-Ni60 alloy composite coating with different contents of WC particles was prepared on the 45steel substrate by high frequency induction cladding. The Composition and microstructure were characterized by X-ray diffraction (XRD) and electron probe X-ray microanalysis (EPMA), the abradability and hardness were tested by UMT-2 tribometer and HV-50A durometer, respectively. The results showed that the hardness and wear resistance of coating were enhanced with the increasing of WC content. WC-Ni60 coating obtained the best wear resistance with the content of 50% WC. The hardness of the coating got the highest when the content of WC was 60%, but wear resistance decreased. The WC-Ni60 coating was reinforced for various hard phases and the metallurgical bonding layer about 10μm was formed between coating and 45steel substrate.
Microstructure Modifications Induced by Pulsed Electron Beam in Steels
Authors: Samih Y. , Bolle Bernard , Alain-Bonasso N. , Hao Sheng Zhi , Dong Chuang , Grosdidier Thierry
Published: February 2011

The present paper presents the first results of an ongoing research dedicated to the analysis of microstructure in steels surfaces treated by Low Energy High Current Pulsed Electron Beam (LEHCPEB). Various steels - 316L (a stainless steel), D2 (a cold-worked die steel) and 4Cr13 (a martensitic steel) - have been treated by LEHCPEB in order to improve the understanding of the surface microstructure modifications induced by this treatment. The microstructures in the modified surface were characterized by microscopy and diffraction techniques.
Effects of Rare-Earth Oxides Doping on Microstructures and Properties of Al2O3/TiAl Composites
Authors: Wang Fen , Wang Xiao Feng , Zhu Jian Feng , Xiang Liu Yi
Published: February 2011

Effects of rare-earth oxides addition (0.38~1.52 mol% of Sm2O3, Eu2O3 and Er2O3) on the property and microstructure of the hot-pressed (1300°C, 2h, 35 MPa) Al2O3 (12 wt %)/TiAl insitu composites have been investigated. The results show that the doping of rare-earth oxides has a positive effect on both mechanical properties and densities of Al2O3/TiAl composites. Densities enhanced with increasing of rare-earth oxides. The flexural strength and fracture toughness were higher than other samples when the rare-earth oxide content was 0.38 mol %. The matrix grains and Al2O3 particles were significantly refined, and Al2O3 particles evenly distributed in the matrix.
Preparation of High Wear-Resistant Ceramic Parts
Authors: Zhang Ai Ju , Li Zi Cheng , Li Zhi Hong , Zhu Yu Mei
Published: February 2011

Preparation of high wear-resistant ceramic parts was studied in this paper. The mechanical property was measured by the three-point bending tester, and the microstructures were analyzed with the scanning electronic microscope (SEM). The experimental results showed that vitrified bond CM2 was suitable for the preparation of high wear-resistant ceramic parts because of its lower refractoriness, and higher bonding strength sintering at 850oC. Moreover, containing 8- 12μm CBN abrasive grains, the ceramic parts reached higher strength and higher wear resistance than other samples.
Synthesis of Pr6O11 Doped ZnO-Based Varistors by Pyrogenic Decomposition of Nitrate
Authors: Zhu Jian Feng , Qi Guo Quan , Mao Hai Bo , Yang Hai Bo , Wang Fen
Published: February 2011

Pr6O11 doped ZnO-based varistor powders were prepared by a method of pyrogenic decomposition nitrate, which were together with ZnO powders, made into rounded mass and sintered at different temperatures. The effects of sintering temperatures on the composition, microstructure and electrical properties of Pr6O11 doped ZnO-based varistors were investigated. The results show that the optimum sintering temperature is at 1150 °C with 6 μm ZnO average grain size and the samples possess the advantageous electrical properties: varistor voltage of about 480 V/mm, non linear coefficient reaching 44 and leakage current of 0.7 μA.
Bulk Metallic Glassy Composites with Excellent Electrical Conductivity and Enhanced Plasticity Fabricated by Spark Plasma Sintering
Authors: Xie Guo Qiang , Louzguine-Luzgin Dmitri V. , Fukuhara Mikio , Inoue Akihisa
Published: February 2011

Large-size Ni-based bulk metallic glass (BMG) composite samples exhibiting simultaneously high strength, enhanced plasticity and improved conductivity were produced by spark plasma sintering of mixed glassy powder blended with high-conductive Cu particulates. This opens new possibilities for the applications of the BMG composites as functional and structural materials.
4A-Molecular Sieve Synthesis by Microwave Heating with Silicon and Aluminum Materials Produced from the Coal Fly Ash
Authors: Bai Guang Hui , Li Peng Cheng , Xu Peng , Chen Shuang Li
Published: February 2011

A new method, using sodium silicate and sodium aluminate synthesize 4A-molecular sieve, was developed by using microwave technology. The sodium silicate was a high modulus liquor by-product of nano-silica production from coal fly ash. Meanwhile, the sodium aluminate was a process by-product of alumina extraction from coal fly ash. Reaction mixture composition was defined as follow:SiO2/Al2O3 ratio in 2.0, Na2O/SiO2 ratio in 1.5, and H2O/Na2O ratio in 65. The gelation process was completed in 1 hr. Microwave crystallization power was (800w) 30%. Microwave crystallization period can last 25 mins. The 4A-molecular sieve was obtained by collecting crystals from the reaction mixture through filtration after washing with water to pH 11-12 and drying inside isotherm oven. The calcium exchange capacity and effective pore size of the product were 316mg/g and 0.4nm respectively. Over 90% of surface pore size reached in sizes of less than or equal to 8μm. Purity of 4A-molecular sieve up to 99%. This method significantly reduced the raw material costs for sodium silicate and sodium aluminate. In addition, the adoption of microwave technology also lowered the energy usage and shortened crystallization time. All these contributed final low costs of 4A-molecular sieve product, which made it possible for many practical applications.
Catalytic Oxidation of NADH on Gold Electrode Modified by Layer-by- Layer Self-Assembly of Thermostable Diaphorase and Redox Polymer
Authors: Zheng Wen Juan , Zheng Hai Tao , Sun Tao , Liu Pu , Suye Shinichiro
Published: February 2011

A redox polymer, poly(ethylenimine)ferrocene (PEI-Fc) was synthesized by attaching ferrocene groups to the backbone of water soluble poly(ethylenimine), and multilayer film in nanoscale was assembled on gold electrode by alternate layer-by-layer adsorption (LBL) of the positively charged PEI-Fc and the negatively charged thermostable diaphorase (DI) from B.Stearothermophilus. The LBL process was monitored and analyzed by quartz crystal microbalance (QCM) technique, which confirmed the formation of the multilayer structure. The electrochemical oxidation of coenzyme (reduced nicotinamide adenine dinucleotide, NADH) was observed on the electrode fabricated with PEI-Fc/DI multilayer film, and the influence of layer number on current response was investigated. The modified electrode retained ca. 65% relative response after storage in buffer for two months and 50% relative response after incubation at 80 °C for 3 min, which inferred that the multilayer structure was unique stable. A NAD-dependent glucose-6-phosphate dehydrogenase (G6PDH) was also immobilized via the same LBL technique, and electrode modified with PEI-Fc/DI/G6PDH film exhibited current response to glucose-6- phosphate in the presence of free NAD+.
Microwave Hydrothermal Synthesis of GaN Nanorods
Authors: Li Dong , Wang Fen , Zhu Jian Feng , Liu Da Wei , Wang Xiao Feng , Xiang Liu Yi
Published: February 2011

The GaOOH Nanocrystal rods were successfully synthesized by microwavehydrothermal method using Ga2O3 ,HNO3 and NH3·H2O as raw materials. Simple heat treatment of GaOOH in the flow of NH3 gas leads to the formation of submicron GaN rods even at 800°C through GaOOH. The resultant GaOOH and GaN nanomaterials were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The growth mechanism of GaOOH and GaN was proposed. The results indicate that the as synthesized GaN were hexagonal nanorods with average aspects ratio of 5:1(diameter 800 nm and length about 4μm). Photoluminescence spectrum shows that a blue emission peak originates at 473.5 nm, indicating that the GaN nanorods displayed luminescence emission in the blue-violet region, which was related to crystal defects, and may be helpful for electro-optical applications of GaN material.
Electrospun Tin Oxide Nanofibers with Different Precursor Solution
Authors: Bai Xue , Jia Di , Cheng Bo Wen , Kang Wei Min , Li Quan Xiang
Published: February 2011

In this paper, electrospinning method was adopted to prepare tin oxide nanofibers membrane with three kinds of novel precursor solution PVP/C12H24O4Sn, PVP/ C4H10OSn and PVP/SnCl4. The morphology, surface element, thermal analysis and crystal structure of the fibers membrane were investigated by SEM, EDS, TG-DTA and XRD. The results showed that the organic/inorganic hybrid nanofibers with an average diameter of 300～700 nm can be obtained by electrospinning. But after calcined at 600°C, the loose and porous tin oxide nanofibers membrane with an average diameter of 100～250 nm can be obtained only by using PVP/SnCl4 as preceusor solution, moreover, it showed good fiber forming property. From XRD spectra, it was found that the rutile structure tin oxide finally obtained without other crystalline forms.
Preparation of Ultra-Fine MgO•Al2O3 Spinel Powder and its Metallurgy Behavior in Low Carbon Steel
Authors: Li Yang , Li Shuang Jiang , Zhuang Ying , Li Wei Jian , Jiang Zhou Hua
Published: February 2011

Micron, sub-micron and nanometer sized MgO•Al2O3 ultra-fine powders were prepared by gel precipitation, solid-phase synthesis, sol-gel and flame throwing pyrogenation methods. XRD analysis showed that all of the ultra-fine powder is pure with the single MgO•Al2O3 spinel phase. The powder size was measured by laser granularity analyzer and the average size is 1780, 505 and 60 nm with a quite uniform distribution of particle size. MgO•Al2O3 spinel powder with different granularity were sprayed into molten low carbon steel in MgO crucible and MoSi2 furnace at 1873 K. Quantitative microscopic examination showed that big particle inclusions reduce and small particle inclusions increase, as a result, the average size reduce. Data comparison from spraying powders with different size showed that spraying MgO•Al2O3 of nanometer tends to cause more small inclusions in molten steel. The sprayed steel samples were rolled and heat treated for the mechanical properties tests, which showed spraying nanometer MgO•Al2O3 is the best way to improve mechanical property of steel.
Study on the Application of Silane Coupling Agent in Rice Straw/Poly(butylene Succinate) Composites
Authors: Zhao Yang , Qiu Jian Hui , Feng Hui Xia , Zhang Guo Hong , Shao Liang
Published: February 2011

Rice straw/Poly(butylene succinate)(PBS) composites were prepared by injection molding machine. The influence of content and particle size of rice straw on the mechanical properties of composites indicated that with the increase of rice straw content the tensile strength and fracture strain of the composites was decreased. With the same content of rice straw, the smaller particle size, the more obvious decreased. The influence of dosage of silane coupling agent(SCA) on the composites was studied, the result indicated that with the increase of SCA content, the interface of composite materials significantly improved, the Young’s modulus increased 362% after rice straw was treated by SCA. Thermal analysis showed that the adding of coupling agent didn’t undermine the thermodynamic stability of the composites.
Electrochemical Studies on Al2O3-Coated Spinel LiMn2O4 for Lithium Ion Batteries
Authors: Bai Ying , Wu Chuan , Wu Feng , Wu Bo Rong , Chen Shi
Published: February 2011

Spinel LiMn2O4 was synthesized via a solid state reaction, and modified with Al2O3 thin layers by a chemical deposition method. The electrochemical performances of the as-prepared samples were investigated with cyclic voltammetry (CV) and charge-discharge test. It is found that the Al2O3-coated LiMn2O4 help dramatically retaining the discharge capacity upon long-term cycling. The influences of the heat-treating temperature and the coating amount are discussed and compared. The optimized sample is 1% Al2O3/ LiMn2O4 heat-treated at 500oC, which has an initial discharge capacity of 116mAh/g, and a very slight capacity loss of 1.7% at the 50th cycle.
Compatibilizing Effects of Poly(ethylene Glycol) on PLA/Cellulose Nanowhiskers Composites
Authors: Qu Ping , Bai Lu , Gao Yuan , Wu Guo Feng , Zhang Li Ping
Published: February 2011

One best way to harness the petroleum-based solid wastes is to develop biodegradable materials. Among which, PLA is the most important one, because it is made from renewable plant. But Poly(lactic acid) (PLA) is brittle and low impact resistance. The cellulose nanowhiskers are about 5-40 nm in diameter and the length can be from 100 nm to several micrometers depending on the source of cellulose and the processing technology. The cellulose nanowhiskers can act as efficient reinforcement because of the high aspect ratios, important surface areas and high modulus. The celluloses nanowhiskers are hydrophilic because of the abundant exposed hydroxyl (-OH) groups and PLA is hydrophobic. So we added the low molecular weight polymeric-poly (ethylene glycol) (PEG) to improve compatibility between PLA matrix and the cellulose nanowhiskers. The PLA/cellulose nanowhiskers composites were prepared by casting solution. The tensile strength and the elongation rate of the composites improved 56.7% and 48% comparing with the PLA/cellulose whiskers composites. The thermo gravimetric analysis indicated that the thermal decomposition of PLA/cellulose nanowhiskers/PEG composites include only one stage. The pictures of SEM showed the fracture morphology of the different kind of the composites. The structure of the PLA/cellulose nanowhiskers/PEG composites were characterized by AFM, which showed that the cellulose nanowhiskers dispersed evenly in the PLA matrix.
Synthesis and Application of a Modifier to Enhance General Properties of the Polar Wood
Authors: Jiang Yi Fei , Wu Guo Feng , Zhang Hao , Qu Ping , Pu Jun Wen
Published: February 2011

A preparation method of modifier with low molecular weight and high reactivity is presented. This modifier （called KFK in lab）can impregnate into polar wood along trachea from the ends with pressurized impregnation method. In the following heating and pressing processes of the polar wood, the KFK polymerizes, and it enhances stability and strength of the wood. It showed that the favorable conditions for synthetic reaction of the KFK are: molar ratio of U and F, 1:1; reaction temperature, 20°C; reaction time, 3 hours; dosage of ignition primer A: 5%. Results from test showed the degree of crystallinity tested by XRD were 30%, 32% in different dosage of the modifier. Utilizing a combination of low molecular weight resin impregnation and pressing resulted in a density increase of KFK resin-treated wood from 0.214 to 0.268g/cm3. At the same time, the Young’s modulus and bending strength increased from 1.407GPa to 1.759GPa and 64MPa to 74.5MPa, respectively. It can be concluded that the effective utilization of KFK resin impregnated in polar wood is a promising technique for the production of high-strength in the drying and pressing processing.
Influence of Carbon Nanotubes on Mechanical and Thermal Properties of Glass Fiber Reinforced Vinyl Ester Resin Composites
Authors: Chen Hong Yan , Kong Zhen Xing , Wang Ji Hui
Published: February 2011

Carbon nanotubes (CNTs) were incorporated into glass fiber/ vinyl ester resins composites to improve their mechanical and thermal properties, especially the interlaminar shear and longitudinal compressive strengths which are belong to the matrix-dominanted properties and much weaker than the fiber-dominated properties. In this study, a higher temperature initiator was added to improve the polymerization degree and raise the transition temperature (Tg). Mechanical testing indicated that by adding 0.4 wt% CNTs, the nano-filled composites attributed to 21%, 16%, 10%, and 8% improvement in interlaminar shear strength, compressive strength, tensile strength and flexural strength with respect to their counterparts without CNTs, respectively. Moreover, Thermogravimetric analysis (TGA) also exhibits approximately 14°C higher decomposition temperature than those of conventional composites.
The Time Dependent Behavior of Linear Viscoelastic Polymers
Authors: Zhang Wei Xiang , Shao Xing , Xiao Zhao Ran
Published: February 2011

Polymers have been proved to have attractive mechanical characteristics, which made it desirable to choose these materials over traditional materials for numerous types of applications. As the uses of polymers increase, a thorough understanding of the mechanical behavior of these materials becomes vital in order to perform innovative and economical designs of various components. The main objective of this paper is to develop an effective method with the use of the Laplace inverse transform to describe the time dependent mechanical response of viscoelastic polymers. This general methodology is based on differential constitutive relations for viscoelastic polymers, avoiding the use of relaxation integral functions. As its application, the creep and relaxation properties of the materials are exhibited in the numerical examples.
Influence of Thermal and Thermo-Mechanical Processing on the Creep Resistance of Mg-10Gd-3Y-0,4Zr Alloy
Authors: Janik Vit , Wang Qu Dong , Yin Dong Di , Ding Wen Jiang
Published: February 2011

Alloy Mg-10Gd-3Y-0,4Zr in as-cast, as-extruded, cast-T6 (peak aged) and extruded-T5 (peak aged) state was tensile creep tested at 200, 250 and 300 °C and stress 50, 80 and 120 MPa. Comparison of minimal creep rate shows that alloy Mg-10Gd-3Y-0,4Zr in cast-T6 conditions is characterized by an excellent creep resistance, which is higher than that of commercially available Mg-alloys. Creep resistance of as-cast, as-extruded and extruded-T5 alloy Mg-10Gd-3Y-0,4Zr is lower. Cavity nucleation is heavily affected by the amount of secondary phases on the grain boundaries and also by the initial grain size of the microstructure. After extrusion and in the extruded-T5 conditions creep cavitation was not observed, whereas in the as-cast and cast-T6 conditions creep cavitation occurred on the high fraction of grain boundaries.
Enhancement of Sensitivity for the Evaluation of Electrical Properties by Modifying the Nano Structure of Microwave AFM Probe
Authors: Zhang Lan , Ju Yang , Hosoi Atsushi , Fujimoto Akifumi
Published: February 2011

To confirm the sensitivity in the measurement of electrical properties affected by the nano structure of microwave AFM (M-AFM) probe, three kinds of M-AFM probe with a nano-slit on its tip in different width (75 nm, 120 nm and 160 nm) were investigated. Au and glass samples were measured by the probes working at a non-contact AFM mode. The M-AFM probe with the nano-slit having the width of 75 nm, by which the difference of the measured voltage between Au and glass samples is 55.1 mV, shows the highest sensitivity for detecting electrical properties of materials. As the result illustrated, the M-AFM probe with smaller width nano-slit on the tip can be considered to be an ideal nano structure.
Rolling Contact Fatigue Property of Low-Temperature Bainite in Surface Layer of a Low Carbon Steel
Authors: Zhang P. , Zhang Fu Cheng , Yan Z.G. , Wang Tian Sheng , Qian Li He
Published: February 2011

Rolling contact fatigue (RCF) properties of low-temperature bainitic microstructure in the surface layer of a low-carbon steel, obtained by means of carburization and successive lowtemperature austempering were studied. Comparisons were made with those properties of a martensite steel obtained by quenching and tempering. The results showed that the low-temperature bainitic steel exhibits an excellent RCF resistance and reaches a RCF life more than twice that of the martensite steel, presumably as a consequence of the very thin bainite plates (~80 nm in thickness) and the fine-scale dispersion of austenite between the plates. The apparently increased hardness in the surface layer may partly be the cause of the enhanced RCF resistance.
Numerical Investigation of Temperature and Forming Rate Effect on AA5086 Warm Formability
Authors: Zhang Cun Sheng , Zhao Guo Qun , Chen Hao , Leotoing Lionel
Published: February 2011

The poor formability of aluminum alloy at room temperature limits its use in some products with complex shapes, hence the warm forming process is intended to overcome this problem by using an elevated temperature. Now, the warm formability of AA5086 has not previously been well investigated in the literatures, especially at a rapid forming rate. In this paper, a numerical method has been developed to investigate the warm formability of an AA5086 sheet. Firstly, the dynamic tensile test was carried out under different forming temperatures and forming rates to identify an appropriate constitutive law for the sheet. The inverse analysis was performed to identify the parameter values in the constitutive law. Then based on the commercial finite element program ABAQUS, the Marciniak test was simulated to evaluate the sheet formability of by implementing a user-defined material subroutine UHARD. The effects of forming temperature and forming rate on sheet formability were investigated and it is shown that the formability of AA5086 seems to be insensitive to the forming temperature and forming rate.
Studies on Band Structures and Wave Localization Phenomenon of the Randomly Disordered Two-Dimensional Solid-Fluid Phononic Crystals
Authors: Chen A Li , Wang Yue Sheng , Zhang Chuan Zeng
Published: February 2011

The supercell based plane wave expansion method is used to study the effects of random disorders on the band structures of a two-dimensional (2D) solid-fluid phononic crystal. Phononic systems with steel scatterers embedded in a water matrix are calculated in detail. The radius disorder and location disorder are concerned. The influences of the disorder degree on the first band gap are investigated. The localization phenomenon is discussed by computing the displacement fields in the supercell.
Enhancement in Mechanical Properties of Bamboo by Press Forming
Authors: Takagi Hitoshi , Okitsu Yoshiyuki
Published: February 2011

Raw Japanese timber bamboo was hot-pressed in order to investigate its static and dynamic mechanical properties such as flexural strength, flexural modulus, and impact strength. The purpose of this work was to examine the effect of molding pressure on the mechanical properties of hot-pressed bamboo. The hot-pressing pressures used were varied from 5 to 100 MPa and hot-pressing temperature was fixed to be 160°C. The density, flexural strength and flexural modulus remarkably increased up to 20 MPa, and then gradually increased. However Izod impact strength showed different pressure dependence. In conclusion, remarkable densification both in vascular bundles parts and parenchyma parts was achieved after hot-pressing of bamboo resulting in the increase in density and mechanical properties.
End-Mill Evaluation by Measurement of Cutting Force
Authors: Gomi Nobu , Ishii N. , Hozumi R. , Kumehara H.
Published: February 2011

Evaluation of manufacturing process in milling by direct measurement of cutting force is considered to be effective comparing to indirect measurement of electricity. This paper proposed a new evaluation method of end-mills by the direct measurement of cutting force. Cutting forces were precisely obtained by a 3-component dynamometer during end milling. Each flute cutting forces was evaluated for two types of end-mills (non wear-out, wear-out) by wave patterns of cutting force. A distinctive difference in the two types of end-mills has been clearly seen. The effectiveness of the proposed evaluation method has been clarified.
Study on Hydration Mechanism of Phosphoaluminate Cement
Authors: Liu Peng , Yu Zhi Wu , Chen Ling Kun , Ding Zhu
Published: February 2011

Phosphoaluminate cement (PAC) is a kind of new cementitious material which has many special properties compared to Portland cement (PC). PAC sets quickly and develops early-high strength. In order to investigate the hydration mechanism, the hydration products and microstructure of PAC were studied with x-ray diffraction (XRD), electron scanning microscope (SEM) and electrochemical impedance spectroscopy (EIS). Heat evolution of PAC was also measured. The results show that the hydration mechanism of PAC is different from Portland cement, which is caused by the special minerals including CxP, CA(P), phase L, and so on. The main hydration products of PAC are calcium phosphorus aluminates hydrate (C-A-P-H), calcium phosphate hydrate (C-P-H), aluminates hydrate (C-A-H), the corresponding hydration microcrystal as well as gels. Also, there is no calcium hydroxide produced during hydration. The hydration procedure of PAC is divided into four stages which are dissolution and induction, acceleration, deceleration, stabilization.
Flexural Behavior of Steel Fiber Reinforced Self-Stressing Concrete in Continuous Systems
Authors: Wang Bo Xin , He Huan An
Published: February 2011

Steel Fiber Reinforced Self-stressing Concrete (SFRSSC for short) is a new type of high performance cementitious composite with self-expansive performance and high tensile resistance. It can be used as a joint material in the new bridge construction or the old bridge rehabilitation. Because when SFRSSC is restrained by steel bars and other terminal conditions, it can create chemical pre-stressing force to enhance the cracking moments of the continuous beams. For purpose of utilizing the properties of SFRSSC, the primary goal of this research is to apply SFRSSC as a joint material to build continuous bridges. Firstly, the model experiments of 8 continuous Tbeams with SFRSSC layers are carried out. Secondly, based on the model experiments, flexural performance of the beams reinforced by SFRSSC layers is investigated. Owing to enhancement of steel fibers and self-stress induced by steel bars, the layers greatly improve the first-crack strength and stiffness of the continuous T-beams. The test results obviously indicate that the composite SFRSSC-RC continuous T-beams enhance the crack moment 51.4%～121% more than conventional concrete continuous beams. Furthermore, SFRSSC can help cancel out the relative deformation and stress due to new concrete shrinkage between new and existing concrete during the process transforming simply supported beams into continuous beams. It is concluded that flexural performance of continuous T-beams strengthened by SFRSSC is more greatly improved than that strengthened by conventional concrete.
Numerical Simulation and Deformation Research for Cold Enlarging Tube Diameter
Authors: Kuang Wei Hua , Zeng Ling Liao
Published: February 2011

This paper presented how to build finite element model based on UG NX, and simulated the cold expanding process by DEFORM software. The deformation, distribution and development trend of velocity, equivalent stress, equivalent strain and equivalent strain rate were predicted. The punch’s load-time variation curves in X, Y and Z direction were also obtained.
Selective Laser Melting of Multi-Component Ni-Based Powder Mixture for Building Metallic Parts
Authors: Li Rui Di , Shi Yu Sheng , Wang Zhi Gang , Liu Jin Hui
Published: February 2011

Selective laser melting (SLM) is an advanced manufacturing technology, which is flexible in building three-dimensional (3D) metallic parts. In this work, SLM experiment of a multicomponent Ni-based composite powder, which consisted of Ni, Cr, Fe, and Al powders, was conducted with favorable forming ability. The SEM, EDX, and XRD analysis were used to characterize the surface morphology, microstructure, and phase structure of as-formed Ni-based alloy. The XRD analysis showed that the as-received phase structure was Ni based solid solution. The SEM analysis of surface morphology revealed that metal agglomerates or balls were very easily formed in SLM surface, between which some pore channels existed. The surface condition and porosity could be improved by increasing laser energy input, because of a higher molten temperature and accordingly better flowing and flatting characteristics. The SEM analysis of microstructure showed that the crystalline grains were in cellular and columnar shape. Moreover, the grains were very fine with average dimensions about 5μm, due to the rapid cooling rate with rapid laser beam moving. The EDX analysis illustrated that the element contents of starting powder were uniformly distributed in as-prepared sample. A case investigation into SLM of this composite powder to form an impeller was also performed.
FEM Based Prediction of Residual Stress in Thin-Walled Aluminum Process
Authors: Zhou Ze Bin , Yang Jian Guo , Li Bei Zhi
Published: February 2011

Thin-walled aluminum components are widely used in aerospace industry. The presence of residual stresses in aluminum components usually causes distortion after machining process, making it difficult to guarantee their integrated precision. Therefore, control of machined surface residual stresses is important for this industry. This paper presents an efficient method for modeling the residual stress imparted by machining process. The methodology is based on mathematical model and finite element method to predict the residual stresses during machining process. Through a thermo-mechanically model, machining process output parameters such as cutting forces and cutting temperatures are predicted as part of the overall modeling effort. To verify the modeling simulation, a test on aluminum alloy 7050T7352 is carried out. It is shown that the simulation result is consistent with the experimental one.
Preparation of Semisolid A356 Alloy by a Cooling Slope Processing
Authors: Xu Jun , Wang Tong Min , Chen Zong Ning , Zhu Jing , Cao Zhi Qiang , Li Ting Ju
Published: February 2011

In order to obtain the non-dendritic feedstock for the semisolid forming process, a cooling slope processing was used. In this work, the effects of the angle, length of cooling slope and pouring temperature on the microstructure of A356 aluminum alloy were investigated. It showed that these parameters affect the size and morphology of α-Al phase to some extent. The results indicate that a pouring temperature of 650°C and a cooling slope with 45° in angle and 50 cm in length are the optimum parameters for preparing fine and globular grain structures. To eliminate the solidification shell formed in the surface of cooling slope, a nitride dope was coated on the surface of the cooling slope.
Fabrication of W-ZrC Cermets by Reactive Melt Infiltration with Polycarbosilane as Preforms’ Adhesive
Authors: Zhang Shou Ming , Wang Song , Zhu Yu Lin , Chen Zhao Hui
Published: February 2011

Polycarbosilane (PCS) was introduced into preforms to prepare W-ZrC cermets by reactive melt infiltration (RMI). Properties and microstructure of the preforms and cermets were analyzed with XRD, SEM and EDS. The preforms had an open porosity of 42.0 %, and the WC particles were cemented by the pyrolysate of PCS. W-ZrC cermets were prepared by heating Zr2Cu covered preforms to 1300 °C for 3 h. XRD revealed that the resulting cermets were made up of W, ZrC and W2C. The cermets had an open porosity of 3.5 %, a flexural strength of 354.0 MPa, a flexural modulus of 192.5 GPa and a flexural toughness of 5.72 MPa·m1/2 .
A New Technology for Producing Bimetal Rods
Authors: Duan Yu Ping , Yu Zhen , Liu Li Dong , Liu Shun Hua
Published: February 2011

This paper studied a new technology for producing copper cladding aluminium robs. The Horizontal Core-filling Casting equipments for producing copper clad aluminium rod were designed, and the interfacial compounds and the primary phase were analysized by backscattered electron image and electron probe micro-analyzer, and X-ray diffraction unit. The results showed that middle seam region was white eutectic microstructure and a-Al structure, where the eutectic takes on chrysanthemum distribution and the sharp or the edge of chrysanthemum was CuAl2. The dark region in the middle seam region was a-Al.
Preparation of Polytetrafluoroethylene Ultrafine Fiber Mats with Electrospinning Process
Authors: Zhu Si Jun , Zhou Yuan Yuan , Takashi Ochi , Wu Gang
Published: February 2011

Polytetrafluoroethylene (PTFE) ultrafine fibers mats were prepared by electrospinning of an aqueous PTFE dispersion and a small amount of poly(vinyl alcohol) (PVA) and subsequent heat-treatment. The influence of dispersions composition on the morphology of fabricated PTFE ultrafine fiber mats was investigated. The fabricated mats were characterized by attenuated total reflection-Fourier transform infrared (ATR-FTIR) and koniology tester. The results show that the PVA/PTFE mass ratio of 1:5 was suitable for the PTFE fibers formation. All the PVA in the electrospun PVA/PTFE mats was removed at 350 °C~390°C. The fabricated PTFE ultrafine fiber mats have the potential to be used as high-temperature filter.
On the Crack Defect of CrZrCu Alloy DC Casting Ingot
Authors: Wu Di , Yao Shan , Tang Guang Xing , Yang Tong
Published: February 2011

The CrZrCu alloy cylindrical ingots have been tried to produce by the direct chill (DC) casting process. However crack defect is contained in the central area of the ingots. Metallographic analysis proving a kind of hot crack is cause by the precipitate in grain boundaries. A 3D coupled thermal-stress mathematical model has been formulated to describe thermal and stress–strain fields during the direct chill (DC) casting process for CrZrCu alloy cylindrical ingots. The model has been applied to analyzing the crack defect elimination, so that the need for further refinement of the DC casting process parameters has been satisfied.
Study on the Reaction Mechanism of Al-ZrO2-B4C System
Authors: Zhu He Guo , Chu Da , Wang Huan , Min Jing , Ai Ying Lu
Published: February 2011

The composite (a-Al2O3+ZrC+ZrB2)/Al has been fabricated by using exothermic dispersion synthesis. When the reinforcement volume fraction is 100%, there are two exothermic peaks occurred in DSC curve of the Al-ZrO2 system. But when the reinforcement volume fraction is 30%, there is only one exothermic peak occurred in the DSC curve and the height of it decreases. When the molar ratio of B4C/ZrO2 is 0, the reaction products are consisted of a-Al2O3 grains and Al3Zr blocks. With an increase in the molar ratio of B4C/ZrO2, the amount of the Al3Zr decreases and the phases of ZrB2 and ZrC are formed. When the molar ratio of B4C/ZrO2 increases to 1/3, the Al3Zr almost disappear and the reinforcements of the composites are composed of a-Al2O3, ZrC and ZrB2. The corresponding XRD (X-ray diffraction) patterns also testify this.
Behavior of Hydrogen during Electroslag Remelting Process
Authors: Dong Yan Wu , Jiang Zhou Hua , Liang Lian Ke , Li Zheng Bang
Published: February 2011

Behavior of hydrogen in steel during electroslag remelting process was investigated on a laboratory-scale unit. Results indicated that a considerable amount of hydrogen was picked up by the metal at the beginning of the process. Hydrogen content decreased with the increasing of ingot height. To avoid the hydrogen peak, anhydrous components must be used. Protective atmosphere combining with premelted slag was the optimal measure to control hydrogen in steel when the solid-starting technique was carried out. According to the results in the experiment it was not the crucial factor for hydrogen in steel remelted under protective atmosphere whether slag contained lime or not at actual remelting period.
Effects of Li2CO3 on Properties of Mould Flux for High Speed Continuous Casting
Authors: Lu Yan Qing , Zhang Guo Dong , Jiang Mao Fa , Liu Hai Xiao , Li Ting
Published: February 2011

The effects of Li2CO3 on melting temperature, viscosity, fluidity, surface tension and Al2O3 inclusion adsorption of mould flux for high speed continuous casting were studied. The results showed that with the increase of Li2CO3 content, melting temperature, viscosity and viscous activation energy of mould flux decreased obviously, fluidity increased, surface tension changed little, and Al2O3 inclusion adsorption of mould flux increased. In order to play an effective role, the Li2CO3 content should be less than 4 per cent. The results will play a guiding role in designing of mould flux for high speed continuous casting.
Process Optimization Simulation of Cast-Steel Rear Axle
Authors: Mi Guo Fa , He Bin Feng , Nan Hong Yan
Published: February 2011

In this paper, the View Cast software was used in the optimization of cast-steel rear axle production. The simulation results were adopted in the design of the gating system (including the dimensions of the gating system, the number of the risers and its dimensions) and the iron chills. Practical trial-manufacturing, compared with the numerical simulation, has shown that the new design had effectively eliminated the defect and improved the cast.
Finite Element Simulation of Vacuum Hot Bulge Forming Process of Reactor Coolant Pump Rotor-Can
Authors: Zhu Zhi , Zhang Li Wen , Wu Dong Jiang
Published: February 2011

In this paper, a 2-D nonlinear thermo-mechanical coupled finite element model was developed to simulate the vacuum hot bulge forming process of rotor-can with the aid of finite element software MSC.Marc. Thermal physical and mechanical properties of materials vary with temperature in the model. In addition, the effects of high temperature creep properties of materials on the vacuum hot bulge forming process of rotor-can were considered. The temperature field, the stress-strain field and the displacement field of rotor-can during vacuum hot bulge forming process were calculated. This work is beneficial to understand the vacuum hot bulge forming process of rotor-can and lays a good foundation for future work.
Thermo-Mechanical Analysis of CLAM Steel and SS316L in the First Wall for ITER
Authors: Liu Fu Bin , Yao Man
Published: February 2011

The temperature and strain distributions of the mockup composed of Cu-alloy with distinct structural material (SS316L and China Low Activation martensitic steel (CLAM)) were calculated and analyzed, based on a high heat flux (HHF) test recently reported with heat flux of 3.2MW/m2. The calculated temperature and strain results in the first wall (FW), in which SS316L is as the structural material, showed good agreement with HHF test. By substituting CLAM steel for SS316L the contrast analysis indicates that the thermo-mechanical property for CLAM steel is better than that of SS316 at the same condition. Furthermore, the temperature and strain distributions of the FW were calculated under the condition of normal ITER operation: the surface heat flux is about 0.5MW/m2 and volumetric heating due to neutron radiation is on the order of 15~20 MW/m2.
Finite Element Simulation of Vacuum Hot Bulge Forming of Titanium Alloy Cylindrical Workpiece
Authors: Wang Ming Wei , Wang Chun Yan , Zhang Li Wen
Published: February 2011

Vacuum hot bulge forming (VHBF) is becoming an increasingly important manufacturing process for titanium alloy cylindrical workpiece in the aerospace industries. Finite element simulation is an essential tool for the specification of process parameters. In this paper, a two-dimensional nonlinear thermo-mechanical couple FE model was established. Numerical simulation of vacuum hot bulge forming of titanium alloy cylindrical workpiece was carried out using FE analysis software MSC.Marc. The effects of process parameter on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece was analyzed by numerical simulation. The proposed an optimized vacuum hot bulge forming process parameters and die size. And the corresponding experiments were carried out. The simulated results agreed well with the experimental results.
Simulation Study on Horizontal Continuous Casting of Round Copper Billet with Electromagnetic Stirring
Authors: Wang Tong Min , Sha Ming Hong , Li Jun , Li Ting Ju
Published: February 2011

In this paper, a comprehensive three dimensional mathematical model is built to investigate the effect of electromagnetic stirring (EMS) on continuous casting process of copper round billet. The electromagnetic field is simulated by ANSYS software and the thermal-flow field is simulated by FLUENT software. The coupling between electromagnetic field and thermal-flow field is implemented by user-defined subroutines. The simulation results have good agreement with the experiment ones. The results show that electromagnetic frequency and current intensity have significant influence on the fluid velocity, temperature gradient and sump depth. The optimum current intensity and frequency are found to be 40A and 10Hz respectively.