bluuebunny/crossref_metadata_2025 huggingface dataset:
High-Frequency Ferromagnetic Properties of Nanocrystalline (Co2FeSi)1-x(Al2O3)x Heusler Alloy Films with Uniaxial Magnetic Anisotropy
Authors: Cao Xiao Qin , Li Shan Dong , Cai Zhi Yi , Du Hong Lei , Xue Qian , Gao Xiao Yang , Xie Shi Ming
Published: April 2014

A series of (Co2FeSi)1-x(Al2O3)xHeusler alloy films with various Al2O3-doping were prepared by an oblique sputtering method. It is exciting that the as-deposited films exhibit a very high in-plane uniaxial magnetic anisotropy (UMA) field up to 360 Oe and low coercivity of 12 Oe. Consequently, a very high self-bias ferromagnetic resonance frequency in excess of 5.02 GHz was obtained in as-deposited Co2FeSi films without any annealing. The good microwave ferromagnetic performances and the integrated circuits compatible fabrication process of Co2FeSi films make possible application in RF/microwave devices.
Photocatalytic Activity of CuO/ZnO Heterostructure Nanocrystals under UV-Visible Light Irradiation
Authors: Zhou Xiao Yan , Zhou Peng Wei , Guo Hao , Yang Bo , Ren Ru Fei
Published: April 2014

The p-n junction photocatalysts, p-CuO (at. 0-25%)/n-ZnO nanocomposite were prepared through hydrothermal method without using any organic solvent or surfactant. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, energy dispersive X-Ray spectroscopy, and UV-vis spectroscopy. The results demonstrated that the CuO/ZnO nanocomposite presented a two-dimensional morphology composed of sheet-like ZnO nanostructures adorned with CuO nanoparticles. The photocatalytic activity of CuO/ZnO with different Cu/Zn molar rations and pure ZnO synthesized by the identical synthetic route were evaluated by degrading methylene blue (MB) dye under UV-visible light irradiation. The CuO/ZnO with Cu/Zn molar ratio of 4% exhibits the highest photocatalytic activity compared that of the other photocatalysts under the identical conditions. It is mainly attributed to the increased charge separation rate in the nanocomposite and the extended photo-responding range.
Magneto-Dielectric Properties of Fe3O4/TiO2/PTFE Composites and Antenna Simulation
Authors: Cheng Zhi Hong , Zhang Feng , Huang An Ping , Xiao Zhi Song
Published: April 2014

In this paper, a novel composite of magneto-dielectric mixture Fe3O4/TiO2 filled polymer PTFE was synthesized for a compact antenna application. Magnetic permeability, dielectric permittivity and related loss were measured and optimized. A planar patch antenna performance based on these composites with a center frequency at 1 GHz was simulated. The simulated antenna performances such as impedance bandwidth and radiation efficiency indicated that the antenna fabricated by this proposed composite could exhibit a better electrical property than that of conventional antenna printed on dielectric material.
Influence of Particle Size and Ca Addition on the Magnetic Performance and Microstructure of MnZn Ferrite
Authors: Zhang Ling , Li Xiao Long , Liu Dong , Ying Yao , Jiang Li Qiang , Che Sheng Lei
Published: April 2014

In this work, the influence of Ca addition on the power loss of MnZn ferrites was investigated. Mn–Zn ferrites were prepared by conventional oxide ceramic process from calcined powders of different particle sizes in equilibrium sintering atmosphere. It has been found that the optimal amount of Ca addition varies for the Mn–Zn ferrites synthesized by using powders of different particle size.
Thermodynamics Analysis on Combustion Synthesis of β-SiAlON
Authors: Yi Xue Mei , Niu Jing , Akiyama Tomohiro
Published: April 2014

Combustion synthesis (CS) of β-SiAlON (z= 1) was carried by heating the raw mixtures of Si, Al, and SiO2under a constant nitrogen pressure of 1 MPa to the preconcerted temperature. The temperature profile was recorded by a W-Re thermocouple, which showed several exothermic and endothermic reactions during the entire CS process. The maximum temperature reached above 1900°C, and two main exothermic reactions at ~800 °C and ~1350 °C were found. The XRD analyses indicated that the main intermediate products are AlN, SiO2, and Al2O3before β-SiAlON was synthesized finally. From our analyses, Al reacted with nitrogen gas at ~800 °C first, then at ~1350 °C, the main reaction occurred and the final product was obtained synchronously.
Synthesis and Characterization of Surfactant-Free PDEA/PMAA of IPN Nanogel
Authors: Wang Peng , Zhang Jun Li , Li Xue Ting , Wu Qian , Zhao Di , An Dong , Lu Xi Hua , Qiu Gao
Published: April 2014

Based on the hydrogen bonding between MAA and PDEA, the synthesis of surfactant-free PDEA/PMAA interpenetrating (IPN) nanogels was studied in ultrapure water with N, N-methylene acrylamide (BIS) as a crosslinker, ammonium peroxodisulfate (APS) as an initiator, N,N,N',N'-Tetramethylethylenediamine (TEMED) as an accelerator. First, poly (N, N-diethyl acrylamide) (PDEA) nanogels were synthesized using emulsion precipitation polymerization. As MAA was polymerized in the aqueous dispersion of PDEA nanogels as seeds, PDEA nanogels got interpenetrated with poly (methacrylic acid) (PMAA) due to the effect of the hydrogen bonding between PDEA and PMAA. The chemical structure of the PDEA/PMAA nanogels was studied with Fourier transform infrared (FTIR) spectroscopy. The nanogels morphology was characterized with transmission electron microscopy (TEM) and atomic force microscopy (AFM). And the volume phase transition behaviors and swelling properties were studied with dynamic light scattering (DLS). The experimental results show that the interpenetrating nanogels were very sensitive to temperature. As the amount of MAA increased, the volume of the neutralized PDEA/PMAA nanogels changed less above phase transition temperature and was finally no change. The temperature responsive PDEA/PMAA nanogels will promise to have significant influence on fundamental studies and real applications.
Fabrication and Characterization of Carbon Fiber Paper for Application of Proton Exchange Membrane Fuel Cells
Authors: Yang Kai , Xie Zhi Yong , Huang Qi Zhong , Tang Xian , Hu Rong
Published: April 2014

Using the dry method-prepared polyacrylonitrile based carbon fibers as raw the material, carbon paper applied for proton exchange membrane fuel cells was prepared by the processes of molding, high temperature carbonization, chemical vapor deposition (CVD), and graphitization. The effects of resin carbon content and subsequent heat-treatment process parameters on the properties of carbon paper were studied. The results show that: the resin carbon content is an important factor to affect the density, thickness, through-plane resistivity and porosity of carbon paper. When the resin carbon content is 20%, the thickness of carbon paper is 0.20mm, the density is 0.41g/cm3, and the porosity is 74.5%, in line with requirements of the fuel cell. When the heating time is 4 hours, the porosity is 71.9%.
Facile Synthesis of Highly Ordered Macroporous CeO2 Film for Methylene Blue Degradation
Authors: Liu Cheng Bao , Qian Jun Chao , Chen Feng , Wu Zheng Ying , Chen Zhi Gang
Published: April 2014

Negative-charged PS microspheres were prepared through emulsifier-free emulsion polymerization method. High-quality PS colloidal crystals were obtained via the horizontal deposition method. Hierarchically ordered macroporous CeO2sheets were fabricated on fluorine-doped tin oxide (FTO) substrates using PS colloidal crystals as template by a continuous infiltration process. The structure and morphology of the products were characterized by X-ray diffractometer (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HRTEM) and nitrogen adsorption-desorption. The characterized results showed that macroporous CeO2sheets replicated well three-dimensionally (3D) ordered structure derived from PS colloidal crystals template and possessed a relatively large specific surface area. Moreover, the synthesized hierarchical CeO2sheets showed the highest photocatalytic activity under solar irradiation and also exhibited remarkable ability to remove methylene blue, suggesting they are promising catalyst for wastewater treatment.
Stable Levitation Performance of Bulk High Temperature Superconductor Magnet in Applied Magnetic Fields
Authors: Zheng Jun , Gou Yan Feng , He Da Bo , Sun Rui Xue , Deng Zi Gang
Published: April 2014

Bulk high temperature superconductor magnet (HTSCM) has been considered to get the better stable levitation in applied magnetic field which is not the original field-cooling magnetization (FCM) field in this paper. The vibration disturbance experiments firstly showed that a permanent magnet (PM) can suspend stably under a bulk Yttrium Barium Copper Oxide (YBCO) HTSCM. This implies that the stable levitation of one single bulk HTSCM is able to realize in the other magnetic field even from one single small PM due to the re-magnetization effect. Secondly, it is found that the HTSCM with more trapped flux produced larger guidance forces and smaller repulsion levitation forces compared with the well-recognized FCM condition of the30mm field-cooling height by the permanent magnet guideway (PMG). Especially, the HTSCM with the 0.349T trapped field achieved a maximum 9.8N guidance force, which is over impressive 7 times than the conventional FCM condition. So, it is feasible to introduce the bulk HTSCM into the HTS Maglev transportation system because this pre-magnetization method of the onboard superconductor bulks is not only helpful to improve the levitation capability and stability, but also enhance the dynamic property above the practical PMG.
Studies on the Positioning Effects of Iron Plates on HTS Maglev Performance
Authors: Gou Yan Feng , He Da Bo , Zheng Jun , Sun Rui Xue , Che Tong , Deng Zi Gang
Published: April 2014

Much research work has been done to improve the performance of high-temperature superconducting (HTS) maglev vehicles. However, it is still a long-term task to promote the practical application. In this study, we studied the positioning effects of iron plates which were added to the upper surface (vertical adding way) or lateral side surfaces (lateral adding way) of a bulk superconductor on the maglev performance. Experimental results show that the vertical adding way can bring significant improvement to the guidance force of the bulk sample at specific working position, but the lateral adding way has little effect. These phenomena are explained from the external magnetic field change and corresponding induced current density change inside the bulk superconductor after the addition of iron plates. This work is helpful to understand the performance improvement by introducing ferromagnetic materials to the onboard superconductors.
Preparation of Oleophobic Surface on X70 Pipeline Steel
Authors: Li Hao , Yu Si Rong , Wang Wei
Published: April 2014

The oleophobic surface has extremely broad application prospects in industrial production and daily life. It can prevent the adhesion of materials and fouling, and prolong the service life. In this investition, an oleophobic surface on X70 pipeline steel specimen was prepared successfully by the combination of sandblasting, chemical etching, and low energy modification. The microstructure and oleophobicity of the surface were studied by scanning electron microscope (SEM), contact angle tester, and confocal microscope. The results showed that micro-nanocomposite structure on the specimen was formed after sandblasting and chemical etching of concentrated hydrochloric acid aqueous solution. The low-energy modification of perfluorooctanoic acid anhydrous ethanol solution just covered the surface, but had no obvious influence on the surface morphology. After chemical etching and low-energy modification, the specimen processed by sandblasting for 30s obtained the better oleophobicity, and the maximum contact angle between the surface and engine oil was 130°.
Silk Fibroin/Sodium Alginate Composite Film and Hydroxyapatite Mineralization
Authors: Ming Jin Fa , Yue Xiao Xiao , Zhang Feng , Jiang Yao Xing , Zuo Bao Qi
Published: April 2014

Silk fibroin/sodium alginate blend films and its hydroxyapatite deposition were prepared and characterized by scanning electron microscopy, wide angle X-ray diffraction, Fourier transform infrared analysis, and thermal analysis. The surface of blend films showed much more rod-like structure dispersing uniformity and its average length increasing from 181 to 803nm with increasing the contents of sodium alginate. The crystal structure of silk fibroin and the compatibility of the two components were associated with the content of sodium alginate in silk fibroin/sodium alginate blend films. The silk I and silk II crystal structures of silk fibroin were co-existed in the blend films and a rather complex conformation transition occurred, which was confirmed by wide angle X-ray diffraction and Fourier transform infrared analysis. Thermal behavior of blend films was interrupted by adding different contents of sodium alginate. Adding 30.0% sodium alginate or more, the endothermic peak of moisture evaporation shifted downward from 111 to 80°C, and the degradation peaks at 243 and 279°C, respectively, indicating an obviously two phase structure in the blend films. In addition, the rod-like HAp crystals were grown on the surface of blend films. This result may provide some new ideas in the design and fabrication of new materials through the silk fibroin/sodium alginate composite materials template for the hydroxyapatite crystal growth.
Biocompatibility Evaluation of Cellulose Nanowhisker from Bamboo Fibers for Potential Applications of Drug Delivery In Vitro
Authors: Zhang Yong , Ma Lan , Yu Ye Li , Yao Ju Ming
Published: April 2014

The biocompatibility of the cellulose nanowhisker (CNW) from cellulase hydrolysis was evaluated in vitro for potential applications in drug delivery system. The assessments were comprised of cytotoxicity analysis and proliferation of human osteosarcoma MG-63 cells that were cultured with the resultant CNW. Some morphological and physico-chemical characteristics of the CNW were investigated. The cellulase hydrolysis conditions were optimized at a cellulase dosage of 0.01 mL/g dried fibers, a hydrolysis temperature of 60 °C, hydrolysis time of 3 h and bamboo fiber concentration of 2 wt%. Under these conditions, the as-prepared CNW retained more properties similar to the original bamboo fibers than those fabricated by sulfuric acid hydrolysis. Indirect cytotoxicity test of the CNW revealed it non-toxicity to the cells. The proliferation of the MG-63 cells with the CNW from cellulase hydrolysis was better than that from sulfuric acid hydrolysis. These results together with the fact that the cellulose hydrolysis preparation of CNW is simple and inexpensive make it a good candidate for the design of oral drug delivery device.
Development Model of Circular Eco-Industrial Park for Comprehensive Utilization of Coal Gangue in Coal Enterprise
Authors: Zhan Xiao Yuan , Wang Fang , Song Zhen Qi , Chen Lian Jun , Cui Zeng Di
Published: April 2014

Development of circular economy is a certain choice for economic sustainable development, to establish a circular eco-industrial park for comprehensive utilization of coal gangue in coal enterprise is a new exploration for circular economy. In order to make vast and efficient use of existing and newly increased coal gangue to resolve the serious environmental and ecological problems, the preparation of coal gangue glued stone was investigated. The glued stone products could be used for backfill material; In order to produce the coal gangue glued stone, we heated the coal gangue in the rotary kiln, and the flue gas waste heat could be recovered and used for thermal power generation, and the power is back to the circular eco-industrial park. The mining wastewater could be used for power generation, domestic water and production water after compound purification treatment. Associated effects and synergistic effects of the different industries that integrated and connected with each other could get the double wins between the economic development and the environmental protection.
Adsorption of Lanthanum (III)-Iron (III)-Doped Waste Coal Fly Ash Composite Adsorbent for Reactive Dyes from Aqueous Solution
Authors: Li Bei Gang , Wang Chen , Mi Jing , Ding Lei
Published: April 2014

A composite adsorbent La/Fe/FA for reactive turquoise blue KN-G (RTB KN-G) and reactive brilliant blue KN-R (RBB KN-R) removal from aqueous solution was prepared by loading lanthanum (III) and iron (III) onto waste coal fly ash (FA). The adsorption behavior of RTB KN-G and RBB KN-R on La/Fe/FA was investigated systematically. The results show that the initial dye concentration, contact time, pH value and temperature are all the important factors influencing the adsorption. The adsorption of La/Fe/FA for two reactive dyes at different temperatures were very fast and can establish sorption equilibrium at 30min, and agreed well with pseudo-second-order kinetics. The equilibrium adsorption data could be described by the Langmuir isotherm equation well, and obtained maximum adsorption capacities at 25°C were 56.28 mg/g for RTB KN-G and 116.82mg/g for RBB KN-R, respectively. The rise of temperature was not conducive to adsorption. The results show that the La/Fe/FA adsorbent displays high effective adsorption for reactive dyes and will have potential as a promising application in the field of water pollution control and recycling utilization of resources.
Influence of Homogenization Treatment on Electrochemical Behavior of the Mg-0.8wt%Ga-0.8wt%In Anode Materials
Authors: Yan Feng , Wang Ri Chu , Peng Chao Qun
Published: April 2014

The effects of homogenization treatment on the electrochemical corrosion behavior of Mg-0.8wt%Ga-0.8wt%In anode materials were investigated by the polarization and galvanostatic curves tests. The scanning electron micrographs of the secondary phase after heat treatment and the corroded surface of the specimens were observed. The corrosion product of the Mg-0.8wt%Ga-0.8wt%In alloy was determined by X-ray diffraction. The results show that the intergranular compound dissolved in the Mg matrix in the Mg-0.8wt%Ga-0.8wt%In after homogenizing at 673K for 24h. The least corrosion current density, 0.029mA/cm2, appeared in this specimen due to the least corrosion driving force. The corrosion of the Mg-0.8wt%Ga-0.8wt%In alloy in a 3.5% NaCl solution was generous corrosion and pitting attack. The corrosion product has been found to be mainly Mg (OH)2.
Review on Hydrostatic Extrusion of Magnesium Alloys
Authors: Wang Rong , Zhu Xiu Rong , Shao Zhi Wen , Xu Yong Dong , Wang Jun , Nie Jing Jiang , Zhang Hua
Published: April 2014

Magnesium wrought alloys are of special interest for structural components owing to their improved microstructures and mechanical properties by comparison with Mg cast parts. However, the market of Mg wrought alloys is still relatively small and one of the most important limitations for their application in areas such as aviation and spaceflight is that their strength is still not high enough to be widely used. Currently, more and more attention are paid to hydrostatic extrusion of Mg alloys because the extruded Mg alloys which exhibit extremely fine grains and high strength can be easily obtained by hydrostatic extrusion process. This review detailed the microstructures and mechanical properties of various wrought Mg alloys subjected to hydrostatic extrusion. Furthermore, numerical simulations and processing parameters optimization of the hydrostatic extrusion were also discussed. Finally, the current problems and development trends of hydrostatic extrusion of high-strength Mg alloys were also put forward.
Microstructures and Mechanical Properties of Mg-10Gd-3Y-2Zn-0.5Zr Alloy
Authors: Xu Yong Dong , Wang Jun , Shao Zhi Wen , Wang Rong , Zhu Xiu Rong
Published: April 2014

Microstructures and mechanical properties of Mg-10Gd-3Y-2Zn-0.5Zr alloy were investigated. Three kinds of phases including Mg, Mg3(GdYZn) and Mg12(GdY)Zn were found in the as-cast alloy. Two different patterns of the long-period stacking order (LPSO) phases including lamellar structure and block-like structure were observed in the homogenized alloy and both of them were identified as the phase of Mg12(GdY)Zn. After extrusion with ratio of 10:1 under 420°C, fine dynamic recrystallized grains were obtained and its average size was only about 4μm. The alloy exhibited excellent mechanical properties by hot extrusion and heat treatment. The ultimate tensile strengths of the as-extruded and peak-aged alloys were 415MPa and 480MPa, the tensile yield strength were 335MPa and 410MPa, the elongations were 16% and 13.5%, respectively. The high mechanical properties were mainly attributed to the combined effects of fine grains, LPSO phases and the dispersed precipitates.
Numerical and Experimental Investigation on Hot Backward Extrusion Process of Mg-Gd-Y-Zn-Zr Magnesium Alloy
Authors: Shao Zhi Wen , Zhu Xiu Rong , Wang Jun , Wang Rong , Xu Yong Dong , Zhao Bao Rong , Ling Guo Ping
Published: April 2014

The hot backward extrusion process of the Mg-Gd-Y-Zn-Zr magnesium alloy was investigated by both numerical simulation and experiments. An axisymmetric 2D rigid-plastic finite element model (FEM) was established to simulate the material flow during the extrusion process. The shapes of the dies were optimized in order to avoid severe stress concentration and obtain uniform deformation of the workpiece. After hot extrusion, the microstructures of the alloys were obviously refined, and the secondary phases which included many long-period stacking order (LPSO) phases precipitated in the matrix. The optimal comprehensive mechanical properties of the alloy have been obtained after extrusion and ageing at 200°C for 48h with the ultimate tensile strength of 434MPa, tensile yield strength of 375MPa and elongation of 4.5%, respectively. The good mechanical properties were mainly attributed to the fine microstructures and numerous precipitates in the matrix.
Effect of Cold Machining Process on the Property and Microstructure of Ti-5Mo-5V-8Cr-3Al Strip
Authors: Ni Pei Tong , Zhou Li Peng , Bai Bao Liang , Han Ming Chen , Zhu Mei Sheng
Published: April 2014

Metastable beta titanium alloy Ti-5Mo-5V-8Cr-3Al, with high-strength, favorite ductility and outstanding capacity of cold forming and welding, has been found the applications in sheet metal component, pressure vessel, corrugated shell and cold heading rivet at the temperature lower than 350°C. In the present paper, the effect of cold machining deformation rate and heat treatment process on the properties and microstructures of Ti-5Mo-5V-8Cr-3Al strip were investigated. The results revealed that excellent comprehensive mechanical properties could be achieved with the alloy by reasonable cold machining process and with solution treatment at 800°C followed by gas quenching. Upon a solution and aging treatment at 480°C, the alloy performed favorite plasticity and high ultimate tensile strength of 1250MPa.
Influences of Copper Complexes on the Properties of MAO Ceramic Coating on Titanium Alloy Surface
Authors: Yao Qiang , Yu Si Rong , Chu Hong Chao
Published: April 2014

The present work focuses on the influence of copper complexes in the MAO electrolyte on the structure and wears resistance of ceramic coating on the surface of titanium alloy. The coatings composition and the morphologies were characterized using X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). It is shown that the working voltage of MAO reaction was lower after adding [Cu (NH3)4]2+ than adding EDTA-Cu. The color of ceramic coating is black (prepared in the electrolyte with [Cu (NH3)4]2+) and brown (prepared in the electrolyte with EDTA-Cu). The black coating contained rutile TiO2, anatase TiO2 and aluminium titanate (Al2TiO5), while the brown coating contained rutile and anatase only. The black coating which contained CuO compound was found to outperform brown coating in wear resistance.
Microstructure and Hardness of High Temperature Alloy Ti-1100 Melted in CaO Crucible
Authors: Fu Bin Guo , Wang Hong Wei , Zou Chun Ming , Ma Pan , Wei Zun Jie
Published: April 2014

A high temperature alloy Ti-1100 was produced by vacuum induction melting technology. The effects of casting modulus on the microstructure and hardness of the cast alloys were determined and the results were presented and briefly discussed. Results demonstrate that the microstructure of cast alloys with different modulus are all widmanstatten structure with basket weave features where individual α-laths are separated by a thin layer of retained prior β phase. The greater the modulus, the larger the prior β grain size and α-laths spacing, and the less the Vickers hardness. The roles of the casting modulus governing the microstructures and hardness of the alloys were also discussed.
Microstructural Evolution of High Purity Al-Cu-Mg Alloy during Homogenization
Authors: Li Hui Zhong , Ou Yang Jie , Liao Hui Juan , Liang Xiao Peng , Jiang Jun
Published: April 2014

The microstructure, composition distribution and phase evolution of a high-purity Al-Cu-Mg alloy under homogenization were investigated by optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS) and differential scanning calorimeter (DSC). The results show that severe dendritic segregation exists in Al-Cu-Mg alloy ingot. There are a lot of eutectic phases at grain boundary and the primary phases at grain boundary are Al2Cu and Al2CuMg. The primary phases dissolve into the matrix gradually during homogenization with increasing temperature and holding time, which can be described by a constitutive equation in exponential function. The optimum parameter of homogenization is 500°C for 18 h, which is consistent with the result of homogenization kinetic analysis.
Microstructure, Texture and Mechanical Properties of Mg-2.0Zn-0.3Gd Alloy Sheets Fabricated by Large Strain Hot Rolling
Authors: Luo Jun , Yan Hong , Chen Rongshi , Han En-Hou
Published: April 2014

Mg-2Zn-0.3Gd sheets processed by large strain hot rolling with one pass of 80% reduction at 200°C and 250°C were selected to investigate the rolling temperature effect on the microstructure, texture and mechanical properties of Mg-2Zn-0.3Gd sheets after rolling and subsequent annealing. It was found that the rolling temperatures in the present study seemed to have no obvious effect on the microstructure of Mg-2Zn-0.3Gd sheets during large strain hot rolling process. High density of shear bands and numerous intersected twins but free of DRX grains were observed in the microstructure of both sheets. The Mg-2Zn-0.3Gd sheets showed non-basal textures with peaks tilting to TD after annealing. While the peak intensity of (0002) pole figure increased as the rolling temperature decreasing. Tensile testing results revealed that the Mg-2Zn-0.3Gd sheets rolled at both temperature displayed high room temperature ductility about 40% after annealing, which is due to the existence of non-basal texture.
Study on Anodic Oxidation of 2024 Aluminum Alloys in Sulfuric-Citric Acid
Authors: Meng Xiang Feng , Wei Guo Ying , Zhao Xi Xi , Ge Hong Liang
Published: April 2014

Porous anodic alumina has been obtained through anodic oxidation in a mixed solution of sulfuric and citric acid. We investigated the microstructure and morphology of 2024 aluminum after being anodically oxidized under different voltage and temperature. Hardness and corrosion resistance of anodized aluminum has been also investigated. The results show that after anodization, many nanoholes appeared on the surface layer of the coating. Thickness of the anodized film increased from 2.7μm to 26.3μm with the voltage changing from 10 V to 18 V. Aodized films with the thickness of 18μm could be obtained under the temperature of 47°C. When the oxidation voltage is 12V, the hardness of the oxidation film reached 126HV. Maximum hardness (130 HV) could be achieved when the oxidation temperature was 57°C. After being dealt with in the NaCl solution, the electrochemical corrosion resistance of the anodic film got a sharp increase, and the anodic oxidation voltage had a great impact on the anodized film. When the oxidation voltage was 16V, the corrosion resistance of the film reached the highest value and the corrosion voltage was-0.7V. From the polarization curves, it has been found that the films obtained under the temperature of 37°C possessed more positive corrosion potential (-0.73V) and optimal anticorrosion performance.
Microstructure and Mechanical Properties of Al-Li Alloy 2397-T87 Rolled Plate
Authors: Fan Chun Ping , Zheng Zi Qiao , Jia Min , Zhong Ji Fa , Cheng Bin
Published: April 2014

The microstructure, tensile property and fracture toughness of Al-Li alloy 2397-T87 rolled plate were investigated by optical microscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction, tensile and plane-strain fracture toughness tests. The results show that a pronounced texture variation through the plate thickness was found. Near the surface, Goss texture dominated. While in the center of the plate, typical β fiber texture and a scattering of cube texture were observed. And the subsurface layer exhibited a very weak texture. From the center to the subsurface, the fraction of β fiber texture and cube texture decreased. In contrast, the fraction of shear type texture reaching the maximum in subsurface layer increased. The tensile properties in different layers along the thickness direction were inhomogeneous. The strengths near the surface were lower than those in the center. And the through-thickness strength properties variation in the rolling direction was more remarkable than that in the long transverse direction. In the same thickness layer, the fracture toughness and the strengths were anisotropic. The strengths in the rolling direction were higher than those in the long transverse direction and the short transverse direction, and the strengths in the short transverse direction were the lowest. The fracture toughness in L-T orientation was the highest, followed by that in T-L orientation, and the fracture toughness in S-L orientation was the lowest.
Macro-Distribution of Alloy Elements along the Thickness of the Twin Roll Cast Billet
Authors: Zhu Yuan Zhi , Zhao C.Q. , Li J.C. , Li B.L.
Published: April 2014

The macro-distribution of alloy elements in a billet affects its following processing property, and even the mechanical property of the finishing products. In this study AA1235 aluminum alloy was twin-roll cast into a billet with a thickness of 7.0mm. The billet was dissolved layer by layer. ICP-AES was used to analysis the element distribution through thickness. It has been found that Fe and Si were concentrated at both the bottom surface and the top surface of the billet. A higher concentration of Fe was observed at the bottom surface than that at the top surface owing to the density segregation. The center of the billet had lowest concentration of these two elements. Fe had a higher segregation in the twin roll cast billet than Si.
Investigation on the Grain Growth of Fe-40Ni-Ti Austenitic Steel in Heating Process
Authors: Yuan Shao Qiang , Zhang Xiao Juan , Yang Yue Hui , Liang Guo Li
Published: April 2014

Fe-40Ni alloy, keeping face-centred cubic structure (FCC) at room temperature, possesses similar stacking fault energy to that of austenite in steels at wide temperatures. The grain growth behavior of Fe-40Ni-Ti alloy at high temperatures was investigated by optical microscope and transmission electron microscopy (TEM). The results show that the grains grow very slowly from 880°C to 1160°C at holding time of 150min. At about 1220°C, the grain growing tendency can be clearly observed. At 1300°C, the rain size increases rapidly and coarsens when hold for 30min.TiN precipitates forms during the solidification and and strain induced precipitates can dissolve into the matrix, resulting in the grain boundaries moving easily. The evolution of dislocation configuration is retarded by the strain induced precipitates, which enhances the stabilization of dislocation cells.
Effect of Different Deformation on Microstructures and Properties in 304HC Austenitic Stainless Steel Wire
Authors: Song Ren Bo , Pei Yu , Jia Yi Su , Gao Zhe , Xu Yang , Deng Peng
Published: April 2014

Two different components of Φ5.5mm 304HC stainless steel wires were drawn at room temperature. After the drawing tests, hard wires of Φ4.5mm, Φ3.8mm and Φ3.45mm were obtained. During the process of drawing, the stacking fault energy of the metastable austenitic stainless steel was low, which have caused strain-induced martensitic transformation. By XRD, TEM, martensitic volume fraction measurement, etc., the results show that the strain-induced martensitic transformations of the two different components were different significantly. When the deformation amount was controlled at 33% or less, a small amount of γ → α ' martensitic transformations of two steels has occurred. While the deformation arrived at 52% or more, a large amount of γ → α ' martensitic transformation has occurred. The stainless steel which has a higher Cu content will have a lower martensite content, which results from the reason that Cu has a strong inhibitory effect on the martensitic formation. In addition, the martensitic transformation can also influence properties. With the accumulation of strain, deformation mainly occurs in martensitic structure, which reduces the plasticity.
Effect of Spark Plasma Sintering on the Microstructure Evolution and Properties of M3:2 High-Speed Steel
Authors: Zhou Rui , Diao Xiao Gang , Chen Jun , Du Xiao Nan , Yuan Guo Ding , Sun Gui Fang
Published: April 2014

Effects of sintering temperatures on the microstructure and mechanical performance of SPS M3:2 high speed steel prepared by spark plasma sintering was studied. High speed steel sintering curve of continuous heating from ambient temperature to 1200°C was estimated to analyze the sintering processes and sintering temperature range. The sintering temperature within this range was divided into groups to investigate hardness, relative density and microstructure of M3:2 high-speed steel. Strip and quadrate carbides were observed inside the equiaxed grains. SPS sintering temperature at 900°C can lead to nearly full densification with grain size smaller than 20μm. The hardness and bending strength are higher than that of the conventionally powder metallurgy fabricated ones sintered at 1270°C. However, fracture toughness of the high speed steel is lower than that of the conventional powder metallurgy steels. This can be attributed to the shape and distribution of M6C carbides which reduce the impact toughness of high speed steels.
Research on Ultra-Fast Cooling Heat Transfer Coefficient Affecting Law for Hot Strip Mill
Authors: Jiang Lian Yun , Yuan Guo , Li Zhen Lei , Wu Di , Wang Guo Dong
Published: April 2014

The ultra-fast cooling technology has been developed rapidly in order to develop iron and steel material with high performance. A variety of factors including the strip running speed, water temperature, water spray speed and strip temperature will affect strip cooling aspect during ultra-fast cooling process. These factors, which affect heat transfer coefficient, should be analyzed in order to achieve accurate control of strip cooling path during ultra-fast cooling process. The heat transfer coefficients of the hot rolled strip with various cooling parameters were obtained by numerical calculation method. By comparison, the influencing law that the cooling process parameters had made to heat transfer coefficient were obtained. It was found that strip running speed can affect heat transfer coefficient by influencing residual water distribution on top of the strip surface. Water temperature, water spray speed and strip temperature can also affect heat transfer coefficient with different changing law.
Continuous Annealing Process and Microstructure Property of 1200mpa High Strength Steel by Ultrafast Cooling
Authors: Yu San Chuan , Song Ren Bo , Dai Qi Feng , Gao Zhe
Published: April 2014

The different dilatometric curves of continuous cooling transformation have been determined by DIL805 thermal mechanical simulate, through metallographic and hardness method to study the effect of different cooling rate on the microstructure of transition. The critical point Ac1 and Ac3 of the tested steel are 709°C and 865°C. With the increase of cooling rate, the hardness of the steel and the content of martensite increase. In the laboratory conditions, the steel in this experiment was heated to 780°C, 800°C, 820°C, 840°C and 860°C, for 80s, then slowly cooled to 680°C, and water quenched to room temperature finally. The aging temperature was 240°C for 300s, and the last the sample was air cooled to room temperature. The results show that the microstructure of the annealed experimental steel belongs to martensite and ferrite. With the increase of annealing temperature, the content of martensite, the tensile strength and yield strength of the experimental steel increase, and the elongation decreases continuously. The sample was annealed at 800°C for 80s, then slowly cooled to 680°C and finally water quenched to room temperature. After overaging at 240°C, the samples were obtained with high mechanical properties. The tensile strength, yield strength and elongation are 1223MPa, 605MPa and 9.2%, respectively.
Effects of Cooling Processes on Microstructure Evolution of X80 Pipeline Steel
Authors: Ji Feng Qin , Wang Guo Dong
Published: April 2014

With the development of pipeline industry, the pipeline steels with higher strength and plasticity, better low-temperature toughness and weldability are the main development trend. For bainitic pipeline steels, M/A constituent is the main hard phase. Although the M/A constituent can enhance the strength, the larger block-form M/A constituent can deteriorate low-temperature toughness. Therefore, it is essential to further investigate how to refine the M/A constituent. In the present paper, X80 pipeline steel was cooled to room temperature with various cooling paths after hot compression deformation at the temperature of 800oC. The evolution of microstructure of X80 pipeline steel has been analyzed by optical microscope (OM) and scanning electron microscope (SEM). The experimental results show that increasing the cooling rate can significantly refine M/A constituent and promote the formation of granular bainite, and the bainitic ferrite can be also greatly refined. In addition, the effects of five final temperatures of fast cooling were also investigated.
High Cycle Fatigue Behavior of a Wrought Nickel-Base Superalloy GH4698
Authors: Wang Huan , Yuan Chao , Guo Jian Ting , Zhou Lan Zhang , Qin He Yong
Published: April 2014

Smooth and notched specimens of a wrought nickel-base superalloy GH4698 were subjected to high cycle fatigue (HCF) loading at room temperature and 650°C in ambient atmosphere. The experimental results show that the fatigue strength decreased with the increasing of temperature and cyclic stress, and fatigue limit of notched specimens was lower than that of smooth specimens. The fracture surface presents typical characteristics of fatigue fracture, where both stage I and stage II crack propagation can be found. For the smooth specimens, the single primary crack initiated on the surface or subsurface, while multiple primary cracks initiated on the surface for the notched specimens because of local stress concentration.
Creep Behavior of a Re-Free Nickel-Based Single Crystal Superalloy at High Temperature
Authors: Liang Shuang , Tian Su Gui , Guo Zhong Ge , Xue Yong Chao , Shu De Long
Published: April 2014

The creep behavior of a Re-free single crystal Ni-base superalloy at high temperature has been investigated by means of creep property measurement and microstructure observation. The experimental results show that the creep life of the alloy under the testing condition of 1040 oC/137 MPa was measured to be 556h. In the primary stage of creep, the deformation mechanism of the alloy is dislocations slipping within the γ matrix, and the γ′ phase in the alloy is transformed into the rafted structure along the direction vertical to the stress axis. In the latter stage of creep, the alternate activation of the main/secondary slipping dislocations may twist the rafted γ′ phase to promote the initiation and propagation of the cracks along the interfaces of γ′/γ phases up to the creep fracture. And the various configurations of the rafted γ′ phase appeared in the different regions of the sample, thereinto, the coarsening and twisting of the rafted γ′ phase in the regions near the fracture may be attributed to the bigger plastic deformation.
Effect of Mo on As-Cast Microstructure of a Modified 718 Alloy
Authors: Qi Feng , Sun Wen Ru , Xin Xin , Jia Dan , Hu Zhuang Qi
Published: April 2014

The microstructure of as-cast 718 alloy after modified with Mo has been investigated by means of optical microscope (OM), scanning electron microscope (SEM) and X-ray diffraction (XRD). It was found that the dendrite arm space was widened and the interdendritic area was reduced by increasing Mo addition. And no new phase was precipitated in the modified alloys by Mo addition in the range of the present test. The addition of Mo promoted the precipitated of Laves phase, restrained the formation of δ phase, and elevated melting point of the Laves phase.
Effects of Re on Microstructure of Ni3Al-Based Single Crystal Superalloys
Authors: Chen Jing Yang , Xue Ming , Tang Xin , Cao La Mei
Published: April 2014

The effects of Re on solidus/liquidus temperatures, solidification segregation characteristics of alloying elements, γ′ morphology and volume fraction as well as microstructural stability at 1150 °C have been investigated in two experimental Ni3Al-based single crystal superalloys with and without Re (1.0 wt%) addition. The results indicated that Re addition increased the solidus/liquidus temperatures. The segregation characteristics of Ni3Al-based single crystal superalloys were similar with Ni-based single crystal superalloys, and the solidification segregation ratios of W and Mo increased slightly due to Re addition. Meanwhile, Re addition resulted in more negative lattice misfit, more cuboidal γ′ phase and higher γ′ volume fraction. The kinetics of γ′ coarsening and rafting at 1150 °C was lowered substantially compared with the addition of Re.
Effects of Pouring Temperature on the Tensile Properties and Fracture Behavior of Single Crystal Superalloy DD6
Authors: Xiong Ji Chun , Li Jia Rong , Han M. , Yuan H.L.
Published: April 2014

The effects of pouring temperature on the microstructure and the tensile properties of single crystal superalloy DD6 were investigated. The results show that with the decrease of pouring temperature, the primary dendrite arm spacing increases, and the segregation ratio of main elements decreases obviously. DD6 alloy has the similar tensile behavior under the conditions of the pouring temperatures of 1520°C and 1570°C. The pouring temperature has little influence on the yield and ultimate strengths of DD6 alloy. The yield and ultimate tensile strengths of the specimens with the pouring temperature of 1520°C is little lower than the specimens with the pouring temperature of 1570°C under the testing temperatures at room temperature and 650°C, while the specimens with the pouring temperature 1520°C have higher yield and ultimate tensile strength when the testing temperature is higher than 760°C. The pouring temperature did not have an obvious influence on tensile fracture behavior. It has been observed that the tensile fracture surface belongs to quasi-cleaveage fracture mode at testing temperature of 760°C, but the mix characteristic of quasi-cleaveage fracture mode and dimple fracture mode at the testing temperature of 980°C.
Purification of Magnesium by Vacuum Distillation and its Analysis
Authors: Wang Yu Chao , Tian Yang , Qu Tao , Yang Bin , Dai Yong Nian , Sun Yu Pu
Published: April 2014

Based on thermodynamic analysis, the degree of the separation between magnesium and impurities under vacuum was estimated in this paper. It demonstrated that it may be feasible to purify crude magnesium by vacuum distillation on experimental scale. The high purity (99.98 % or 3N8, mass fraction) magnesium (Mg) was obtained through vacuum distillation using 96 % Mg as a raw material under 15 Pa. The inductively coupled plasma atomic emission spectroscopy (ICP-AES) was applied for the analysis of the raw material and the distilled magnesium for 6 impurity elements. The results indicated that the low-volatile impurities such as Fe, Cu, Mn, Pb, Ca could be reduced at the stage of 873K for 30min and the reduction of total impurity content from 34600 ppm (1N6) for crude magnesium to 180ppm (3N8) upon condensate. In conclusion, purification of magnesium was carried out in an efficient high-yield vacuum distillation system designed and fabricated for purifying 1N6 indigenous magnesium to 3N8 (99.98%).
Grain Refinement of GH4169G Alloy by the Combination of Heat Treatment and Cold Deformation
Authors: Huang Lin Jie , Qi Feng , Sun Wen Ru , Hua Pei Tao , Liu Fang , Yu Lian Xu , Xin Xin , Hu Zhuang Qi
Published: April 2014

The precipitating behavior of δ phase in GH4169G alloy at 910°C was investigated and a novel process for achieving fine-grained GH4169G sheet with average grain size of ASTM13 was proposed. Globular δ phase precipitation precedes that of the plate-like δ phase, forming at grain boundary first and later in grain. After globular δ phase reaches a peak volume, it begins to transform into plate-like in grain boundary, and then the plate-like δ phase forms in grain in certain direction. The grain-fined process includes the following steps:(1) solution treated at a proper temperature, then air cooled; (2) soaked for δ phase precipitation; (3) cold rolled; (4) annealed for recrystallization. Microstructure analysis from optical microscopy (OM) and scanning electron microscopy (SEM) revealed that both plate-like and globular δ phase remarkably restrained the grain growth during annealing recrystallization. The optimum parameters for the grain refinement were determined finally.
Directional Solidification Behavior of CMSX-6 Superalloy
Authors: Zheng Shuai , Jia Yu Liang , Tang Jiao
Published: April 2014

The directional solidification behavior of a first generation single crystal superalloy CMSX-6 was investigated. The solidification rate range in 25μm/s to 100μm/s and a thermal gradient G of 30K/cm were used for the present study. The experimental results show that the primary dendrite arm space (PDAS) decreased from (432±8) μm to (369±4) μm as the solidification rate increased, and the sizes of the eutectic pools also decreased as the solidification rate increased. And the volume fractions of eutectic γ/γ' were about 7% to 9% with different solidification rate. The γ/γ'- eutectic was comprised with coarse γ' phase and fine γ/γ' network. The morphology of the γ/γ’ eutectic supported the possibility that the solidification of γ/γ’ eutectic initiates with the formation of fine γ/γ’.
Electronic Failure Analysis of Plate-Capacitors Bonding with Conductive Adhesives
Authors: Song Zhi Ming , Li Hong Wei , Wang Bin , Cao Qian Tao , Hu Ying Lu , Zhang Qiang
Published: April 2014

The long-term stability of microelectronic devices is crucial for their practical applications. However, silver particles in the conductive adhesive can migrate easily under certain conditions, resulting in failure of the devices. In this investigation, the migration of silver particles has been studied by using the devices of Plate-capacitors in the cavity that are bonded with conductive adhesives. The experimental results show that the migration of silver particles occurred in the condition of humid environment with an applied direct current (DC) electric field. Also, the migration of silver particles under a variety of humidity was analyzed, and the reasons causing the failure of the devices were demonstrated.