bluuebunny/crossref_metadata_2025 huggingface dataset:
The Enhancement of Integrated Properties of WC-Co Coatings Fabricated Using an HVOF Spraying
Authors: Li Ming Cheng , Jean Ming Der , Chou Jyh Horng , Lin Bor Tsuen
Published: February 2011

This study reported on Taguchi-Fuzzy logic model with statistical experiments to characterize the tungsten carbide/cobalt (WC-Co) deposited quality properties of the high-velocity oxygen-fuel (HVOF) process. The eight control factors were designed in a factorial orthogonal array experiment, and the effects of control parameters on the integrated surface properties were critically evaluated in the Taguchi designed experiments. A fuzzy logic system with knowledge bases in the inference engine was used to explore the relationships between variables and responses in the modified structures. In addition, the structure and properties of HVOF sprayed WC-Co coating were reported. Furthermore, a confirmation experiment of the optimal process was conducted. It was clear that HVOF sprayed WC-Co coating estimations are greatly improved through the Taguchi-Fuzzy logic operation, and these findings achieved the desired values in the modified properties.
Environmental Degradation of Carbon Fiber Reinforced Polymer (CFRP) and Steel Bond Subjected to Hygrothermal Aging and Loading
Authors: Li Shan , Ren Hui Tao , Lu Yi Yan , Shi Mu Huan
Published: February 2011

Carbon fiber-reinforced polymer (CFRP) material is increasingly being used for the repair of steel structures, mainly because of their superior mechanical properties. However, there is insufficient information on the environmental durability of CFRP-steel bond, especially in hygrothermal aging combined with sustained load. In this paper, 500 mm long І steel beam specimens reinforced with externally bonded wet-laid CFRP sheets are investigated. The specimens are subjected to a sustained four point flexural load of about 30% of initial ultimate load, placed into hygrothermal condition. The ultimate bear capacity and the failure characteristics of the CFRP and steel interface are studied after hydrothermal age and loading. The test results show that the coupled action of sustained load and hygrothermal aging reduces the bond strength of CFRP-steel, even for relatively short conditioning periods, and appears to significantly affect the failure characteristics of specimens.
Comparative Study of Magnetic Abrasive Finishing in Free-Form Surface Based on Different Polishing Head
Authors: Ji Shi Ming , Xu Ya Min , Chen Guo Da , Jin Ming Sheng
Published: February 2011

Nowadays, researches concerned magnetic abrasive finishing (MAF) are becoming increasingly popular. Polishing head is one of the most important factors in the whole polishing system in which magnetic abrasive act directly on the workpiece. In this paper, two kinds of polishing heads applied in the polishing of free form surface are proposed. They are hard polishing head and soft polishing head, respectively. And some important factors are contrasted such as selfsharpening capacity, morphology distribution, and removal uniformity. Moreover, the finishing force is the key factor which is different between the two polishing heads having a great influence on polishing effect. Through comparison and analysis, the soft polishing head is better to finish free form surface. And the experimental results reflect its superiority in polishing free form surface.
Microstructure and Mechanical Properties of Al2O3/TiAl In Situ Composites Doped with Fe2O3
Authors: Xiang Liu Yi , Wang Fen , Zhu Jian Feng , Wang Xiao Feng
Published: February 2011

Al2O3/TiAl in situ composites were successfully prepared by vacuum hot-pressing method with elemental powder mixtures of Ti, Al, TiO2 and Fe2O3. The effect of Fe2O3 addition on the microstructures and mechanical properties of Al2O3/TiAl composites has been investigated. The results show that the Rockwell hardness, flexural strength and fracture toughness of the composites increase with increasing Fe2O3 content. When the Fe2O3 content is 0.84 wt %, the flexural strength and the fracture toughness reach the maximum value of 624 MPa and 6.63 MPa·m1/2, respectively. The improvement of mechanical properties is firstly associated with a more homogeneous and finer microstructure developed by addition of Fe2O3; secondly, it is related to the increase of the ratio of α2-Ti3Al/γ- TiAl matrix phases.
Static and Dynamic Crushing Behaviors of Aluminum Foam
Authors: Wang Qing Chun , Niu Hao Long , Wang Guo Quan , Wang Yu Xin
Published: February 2011

Quasi-static and dynamic axial crushing tests were carried out to investigate the energy absorption capacity of aluminum foam with several densities. First, aluminum foam samples with three densities were crushed quasi-statically to study their compression characteristics, the stress strain relationship curves and energy absorption capacities were achieved from the test results; then dynamic crushing tests were carried out to check the crushing behaviors of the corresponding samples; finally, the energy absorption capacities of tested samples were compared. According to the tests results, all the aluminum foam samples showed very good isotropy and very high mass specific energy absorption capacities. For the crushing tests, the dynamic crushing behaviors were very similar to the static ones, which meant aluminum foam was insensitive to the crash velocity tested.
Surface Effects on Bandgaps of Transverse Waves Propagating in Two Dimensional Phononic Crystals with Nanosized Holes
Authors: Zhen Ni , Wang Yue Sheng
Published: February 2011

In this paper, a method based on the displacement-traction map is developed to calculate the bandgaps of transverse waves propagating in a 2D phononic crystal composed of nanosized circular holes in a square lattice. The Young-Laplace equation is employed to take into account of the surface effects of the nanosized holes. Detailed calculations are performed for the system with nanosized circular holes in an aluminum host with or without the surface effect. The result shows that all bands descend with the first bandgap becoming wider due to the existence of the surface effects.
In Situ Stress Measurement Method Based on X-Ray Diffraction under Biaxial Tensile Loading
Authors: Ju Dong Ying , Wang J.G. , Abe Minoru
Published: February 2011

The purpose of this investigation is to detect damage from stress distribution in the surface of near pre-crack tip by using X-ray diffraction technique during biaxial tension test. An measurements apparatus to measure stress distribution along pre-crack direction was fabrication by use of a biaxial tensile test device and a stress analyzer based on single exposure technique with one position sensitive proportional counter. Stress distribution with different tensile applied stress ratios were measured during biaxial tension test. As results, the shape of actual stress was keeping increase with increasing tensile applied stress. At maximum applied stress, the residual stress increases with the increasing distance from the crack tip; after reaching a maximum it gradually diminish.
Mechanical Properties of Centrifugal Casting Al-Cu Alloys
Authors: Liu Ai Hui , Sui Yan Wei , Li Bang Sheng , Guo Jing Jie
Published: February 2011

In this work, the effects of centrifugal radius and mould rotation speed on the tensile strength, yield strength, specific elongation, and microhardness on Al-Cu alloy castings are investigated. The results show that, with increasing the centrifugal radius or mould rotation speed, the mechanical properties increase gradually. With increasing the centrifugal radius, the variation amplitude of mechanical properties of Al-Cu alloys at mould rotation speed 600rpm is greater than that at 300rpm. This is due to the finer microstructure and the strengthened grain boundary and then resulting in the increase of the resistance to dislocation slipping.
Research on the Self-Thickening Effects in the Process of Fabricating Aluminum Foam Using Semi-Solid Melt by Mechanical Stirring
Authors: Li Nan , Xing Shu Ming , Bao Pei Wei , Liu Zhi Min
Published: February 2011

This paper investigated the self-thickening effects on fabricating close cell aluminum foam directly using semi-solid melt by mechanical stirring without adding other particles. Using the high viscosity character of semi-solid melt as well as mechanical stirring technique, blowing agents (TiH2) could be homogeneously distributed without other thickening additions such as CaO or TiC which were commonly used to thicken aluminum melt in metal foam industry. It was observed that the semi-solid melt could reach a proper condition for the blowing agents to separate and foam after self-thickening process and the solid fraction played a key role in self-thicken effects compared to the stirring time and speed. The self-thickening effects could meet the purity requirement of melt as well as to fabricate aluminum foam with small pores and good structure using precursors. Aluminum foam was a multi-functional material with features of ultra-light, high-toughness, impact resistance, high specific strength, high specific stiffness, heat isolation and fire retardant [1]. The viscosity of melt was extremely important in the process of fabricating aluminum foam. Jin.I and Kenny.LD did some research on the effects of adding solid particles to thicken the melt and their study showed that the best thickening effect could be obtained when the particle size of 5-20 mm and the proportion of 10~20% of liquid aluminum [2]. Miyoshi.T also did some research on the stirring time in the thickening process and showed that adding Ca particles of 1.5~3%(wt) could effectively controlled the viscosity [2]. Research by J.Banhart showed shat 1-5 %(wt) Al2O3 and SiC adding particles could also thicken the semi-solid melt very effectively[3] [4]. Berry.CB and Hall.CG’s research showed that blowing air, oxygen or other gases could also reach thickening effect [2]. There were several methods to thicken the melt but the same ultimate goal was to obtain a suitable melt environment for distribution and foaming of blowing agents. This paper mainly investigated the effects of the self-thickening semi-solid melt on the distribution behavior of blowing agents. Taking the advantage of the high viscosity of semi-solid melt as well as mechanical stirring technique, without adding other thickening particles, blowing agents (TiH2) could be homogeneously distributed in the semi-solid melt. The parameters such as solid fraction, stirring time and speed were investigated in this paper.
Progress in Research on Explosion Induced Thixotropy of Concrete
Authors: Shao Peng , Liu Yu Yang , Zhou Li Fen , Wu Yu Qi
Published: February 2011

Thixotropy is an important property possessed by fresh concrete of changing from gel to liquid under shearing stress and returning to the original state when at rest. The thixotropic process is usually described to be an isothermal and static (or quasi-static) gel-sol-gel transformation. Now the thixotropy of concrete subjected to explosive loads became a new subject in research of synchronous explosive lining technology, which offers an advanced trechless method for underground space construction in soil. Because the detonation of explosives is a short-duration process accompanying with high temperature and high pressure, thixotropic behavior of concrete is no longer as same as that of in general meaning. This review summarizes the recent progress in research on explosion induced thixotropy of concrete, including the thixotropic behavior, thixoforming, influence of thixotropic process on microstructure, macrostructure and mechanical performances of concrete and steel fibre reinforced concrete. Additional, some arguments and suggestions for the future research are presented.
Effect of Rare Earth La Modification on Microstructure and Properties of ZL101 Alloy
Authors: Zhang Xiu Mei , Shi Zhi Ming , Zhang Rui Ying
Published: February 2011

In this paper, rare earth La modifying ZL101 alloy was studied by using of optical microscope, scanning electron microscopy, universal materials tester and small-load Brinell hardness. The influence of T6 heat treatment of the alloy’s microstructure and properties was also studied. The results show that microstructure and mechanical properties of the alloy have much obvious modification effect at modification temperature (690°C). The microstructure and mechanical properties are improved remarkably when La content is up to 0.15wt%.
Effect of Sputtering Process Conditions on Microstructure and Mechanical Properties of Pt-Fe Nano Film
Authors: Ishiguro S. , Ogatsu R. , Inami T. , Nakano T. , Ju Dong Ying , Abe N. , Ishigawa K.
Published: February 2011

One of the vertical magnetic recordings medium materials of the hard disk drive (HDD) is a Pt-Fe thin film. The development of ultra-high density magnetic recording medium in next generation is expected the magnetic disks such as HDD with capacity enlargement of the data. In order to study effectiveness of the proposed sputtering method, we evaluated micro structure, magnetic and the mechanical properties of a Pt-Fe thin film by some sputtering process conditions. From research results, effect sputtering conditions on micro-structure and mechanical properties of Pt-Fe nano film are verified.
Effects of Interfacial Friction on the Microstructures of Magnesium-Tin Alloy during Continuous Rheo-Forming Process
Authors: Zhao Zhan Yong , Guan Ren Guo , Cao Fu Rong , Chen Li Qing
Published: February 2011

The influence of the interfacial friction on the continuous rheo-forming microstructures of magnesium alloy. The effects of interfacial friction on the microstructure evolution in magnesium alloy were investigated. It was shown that strong shear stress and internal friction occur inside the melt under the interfacial friction. In roller-shoe chamber, the growth direction of dendrites growing along the normal direction of the roller near the roller-shoe is changed under shear stress and melt resistance force. when the degree between dendrite and normal direction of roller is about 45 degree, the dendrites can be stablized and grow easily along this direction. Under an appropriate pouring temperature, with the increase of pouring temperature, there is enough room for the grains near the roller-shoe to grow, the grains are not easy to collide mutually, so the dendrites form. In roller-shoe chamber, coarse dendrites near the roller become gradually refined when they grow into the mushy region. Moreover, because dynamic friction force and shear stress of roller are stronger at the exit of the chamber, dendrites fracture and fracture layer or cracks appears. The microstructures consist of mainly rosette and spherical grains on the central position.
Experimental Investigation of Damage Characteristics in Steel Honeycomb Sandwich Beams
Authors: Lu Jie , Zou Guang Ping , Liu Bao Jun
Published: February 2011

Honeycomb sandwich structures are generally designed to carry flexural loads. However, mechanical properties can be influenced by accidental impacts, or service conditions. Thus a nondestructive detection testing is desired for them. In contrast to many conventional nondestructive evaluation (NDE) techniques, acoustic emission (AE) technique permits continuous damage inspection, classification and identification of failure modes in real time. In this work the fracture process of steel honeycomb sandwich beams has been investigated by in-situ AE technique. Pre-cracks were made both for L-direction and W-direction specimens subjected to three-points bending loads. Damage initiation sites were observed in the vicinity of the crack tip. A series of curves among the AE hits, AE amplitude, AE energy and loading time were obtained. Damage characteristics were discussed based on the above parameters. The results indicate AE characteristic parameters can reflect the damage and failure process of specimens. A good agreement was found between the experimental and analytical results.
Study of Photocatalytic Activities with Copper Hydroxyphosphate
Authors: Zhang Hui , Hua Jia Yi , Lü Xiao Meng , Sun Su Wen , Xie Ji Min
Published: February 2011

Copper hydroxyphosphate,as self-assembled nanoparticles, was synthesized by using a hydrothermal method,with cupric acetate (Cu(CH3COO)2·H2O) and diammonium hydrogen phosphate ((NH4)2HPO4) as raw materials. Physical property of copper hydrophosphate was characterized by X-ray diffraction (XRD), Field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), and Ultraviolet obvious diffuse reflection(UV-vis DRS). No surfactants or templates were added in the procedure of preparation. By simply adjusting the pH from 3 to 9, the morphology of copper hydrophosphate varied from microrods to walnutshaped microspheres. Photocatalytic activity of the samples was also investigated. Photo decoloration of Rhodamine B in water under visible light irradiation shows that copper hydrophosphate (pH=7) have the best photocatalytic activity: Photodecoloration activity of 100 mL Rhodamine B (10 mg/L) was 98 % under illumination for 30 min.
Influence of High Current Pulsed Electron Beam (HCPEB) Treatment on Wear Resistance of Hypereutectic Al-17.5Si and Al-20Si Alloys
Authors: Hao Y. , Gao Bo , Tu Gan Feng , Wang Z. , Hao Sheng Zhi
Published: February 2011

The paper reports an analysis of the effect of high current pulsed electron beam(HCPEB) on microstructure transformations and wear resistance of hypereutectic Al-Si alloys. HCPEB treatment with 2.5 J /cm2 energy density leads to the formation of “halo” centered on primary Si, composition homogeneity, the formation of supersaturated solid solution of Al and grain refinement of top melted surface layer. The wear resistance of 15 pulse-treated Al-17.5Si and Al-20Si alloys is drastically improved by a factor of 6.5 and 2, respectively. The increase of hardness in modified surface layer has a positive effect on wear of hypereutectic Al-Si alloys.
Study on Shrinkage and Cracking Performance of SAP-Modified Concrete
Authors: Chen De Peng , Liu Chun Lin , Qian Chun Xiang
Published: February 2011

SAPs (Super Absorbent Polymers) are a group of polymeric materials that have the ability to absorb a significant amount of liquid many times their own weight from the surroundings and to retain the liquid within their structure without dissolving and to desorb it in the dry environment. The shrinkage and cracking performance of SAP-modified concrete was studied by experimental investigation, which express as total cracking area from early-age plastic cracking tests and shrinkage rate (restrained and unrestrained) from shrinkage tests respectively. The effect of SAP on shrinkage and cracking of concrete was compared with that of using pre-soaked ceramsite or perlite. The results show that SAP can effectively improve the cracking and shrinkage of concrete with achieving a 30-50% decrease. SAP particles improve the shrinkage and cracking performance of concrete in three ways as absorption-desorption, some absorbed water being bonded with hydrogen bond of macromolecule and filmforming on SAP particles. The coupling effect of SAP retards the water losing and change the moisture distribution in concrete, and thus reducing the cracking and shrinkage of concrete.
Post and In Situ Characterization of Strain Control and Crystal Quality in Quantum Well Solar Cell Structure
Authors: Wang Yun Peng , Deura Momoko , Sugiyama Masakazu , Nakano Yoshiaki
Published: February 2011

To improve current matching in a tandem solar cell, a strain-compensated InGaAs/GaAsP multiple quantum-wells (MQWs) structure was grown within the middle GaAs PN junction, using metal organic vapor phase epitaxy (MOVPE) on GaAs substrate. Aiming at an accurate design of adsorption edge and precise control of crystal quality in MQWs, post- and in situ characterization was applied in such a fabrication process. Here, we report some applications of some post-characterization such as: X-ray scanning and reciprocal mapping in clarifying composition and crystal quality in these structures; photoluminescence (PL) and FTIR in determining adsorption edge and even indicate some irradiative recombination features as well. By employing an in situ optical surface reflectivity measurement, we established a way of and evaluating an instant of strain relaxation in the course of MOVPE, which deteriorates crystal quality significantly. When strain balancing was incomplete, surface reflectivity dropped during the growth of MQWs, indicating lattice relaxation. The accumulated strain, which is defined as the average strain per period of QW multiply the number of stacking for MQWs , was roughly constant for all the MQWs samples in our experiment. Therefore, it may indicate that this overall strain may be used as a tentative criterion of critical value for lattice relaxation or to predict the maximum number of MQWs for a given value of the average strain per QW period. Combining both post and in situ characterizations, we can effectively adjust the overall strain to get defects free growth for MQWs, and also significant features can be observed for better understanding the heterostructure management.
Tool Wear and Reactions in 304 Stainless Steel during Friction Stir Welding
Authors: Sato Yutaka S. , Muraguchi Masahiro , Kokawa Hiroyuki
Published: February 2011

Four kinds of the welding tools made of PCBN, W, WC and Al2O3 were applied to FSW of 304 stainless steel, and then the wear and reaction between the tool debris and the steel matrix were examined for each tool material. Severe tool damage was found in W, WC and Al2O3 tools after FSW, while the PCBN tool was hardly worn. Formations of Cr-rich borides, ferrite phases containing the high W contents and Cr-rich carbides were found in the stir zones produced using PCBN, W and WC tools, respectively. It was suggested that formation of those phases could be expected by calculation using the thermochemical database.
Effects of Annealing on Microstructure and Microhardness of TA15 Titanium Alloy Processed by Equal Channel Angular Pressing
Authors: Zhao Yan , Guo Hong Zhen , Shi Zhi Feng , Zhang Yong Qiang , Yao Ze Kun , Tan Li Jun , Wang Tao
Published: February 2011

The primary purpose of the present work is to investigate the effects of annealing after equal channel angular pressing (ECAP) on microstructure and microhardness of TA15 titanium alloy. A study was performed by annealing treatment on the microstructure evolution and microhardness variation of ECAPed TA15 alloy. The results state that, static recrystallization occurred distinctly during annealing after ECAP. Since a sample was annealed at a proper temperature and for proper time after ECAP, a larger amount of well globularized and more homogeneous equiaxed α phase has been attained, grains have not grown observably, and the relief of residual stress and work hardening for subsequent processing and using has also been achieved. Accordingly, the optimum annealing parameters of ECAPed TA15 alloy were optimized to be 973 K and 1 hour. The microhardness level of the sample annealed after ECAP was lower than that unannealed, and the microhardness level decreased with the increasing annealing temperature and time.
A Method for Evaluating Intensity of Water Cavitation Peening Processing
Authors: Han B. , Ju Dong Ying , Yu Xiao Guang
Published: February 2011

Water cavitation peening (WCP) with aeration, namely, a new ventilation nozzle with aeration is adopted to improve the process capability of WCP by increasing the impact pressure induced by the bubble collapse on the surface of components. In this study, in order to investigate the process capability of the WCP with aeration a standard N-type almen strips of spring steel SAE 1070 was treated byWCP with various process conditions, and the arc height value and the residual stress in the superficial layers were measured by means of the Almen-scale and X-ray diffraction method, respectively. The optimal fluxes of aeration and the optimal standoff distances were achieved. The maximum of arc height value reach around 150μm. The depth of plastic layer observed from the results of residual stresses is up to 150μm. The results verify the existence of macro-plastic strain in WCP processing. The distributions of residual stress in near-surface under different peening intensity can provide a reference for engineers to decide the optimal process conditions of WCP processing.
Influence of Pulsed Electric Current on Dendrite Growth of Sn-Bi Alloy via Real-Time Observation
Authors: Zhu Jing , Wang Tong Min , Xu Jing Jing , Chen Zong Ning , Xie Hong Lan , Xiao Ti Qiao , Xu Jun , Li Ting Ju
Published: February 2011

External fields (e.g. electromagnetic field, electric field, etc.) are often applied to modify the solidification structure of metallic alloys. The dynamic process of structure modification is invisible because of the opacity of metallic alloys. To understand the modification mechanism, it is necessary to discover the microstructure evolution during solidification. In present paper, we focus on studying the influence of pulsed electric current (PEC) on dendrite growth of Sn-Bi alloy by insitu and real time observation using the third synchrotron X-ray source at Shanghai Synchrotron Radiation Facility (SSRF) in China. The modification mechanism of PEC on solidification structure is analyzed based on a series of real time observations.
Preparation and Properties of 2D C/SiC Composites by CLVD Processing
Authors: Chen Si’an , Hu Hai Feng , Zhang Chang Rui , Zhang Yu Di , He Xin Bo , Mei Min
Published: February 2011

Chemical liquid-vapor deposition (CLVD) process is a new style of fast densification, which combines the advantages of PIP process and CVI process. 2D C/SiC composites were prepared at 800~1200°C for 3~4 hours with liquid polycarbosilane and carbon fiber cloth by CLVD process with induction heating, and had the density of 1.7 g/cm3, the flexural strength of 84.6MPa, and the flexural modulus of 20GPa. XRD pattern of the sample proved that the matrix was β-SiC. It was found that SiC deposited mainly around single fiber instead of among fiber bundles and layers.
Fe-Cr-C-TiC High-Chromium Fe-Based Ceramic Composite Coating Prepared by PTA Weld-Surfacing Process
Authors: Wang Li Mei , Liu Jun Bo , Yuan Chi
Published: February 2011

In situ synthesized Fe-Cr-C-TiC high-chromium Fe-based ceramic composite coating was fabricated on substrate of Q235 steel by plasma transferred arc (PTA) weld-surfacing process using the mixture of ferrotitanium, ferrochromium, ferroboron and ferrosilicium powders. The microstructure and wear properties of the composite coating were investigated by XRD, SEM, EDS, microhardness tester and wear tester. Results show that the coating consists of TiC, (Cr,Fe)7C3 and austenite. The coating is metallurgically bonded to the Q235 steel substrate. TiC particles formed by PTA weld-surfacing process present cubic, dendrite and flower-like shape. The wear resistance of the composite coating is approximately 11 times higher than that of the base body Q235. As the load increases, the wear mass loses slowly, which demonstrates the composite coating has excellent load character.
Microstructure and Wear-Resisting Property of Submerged-Arc Welding Fe-Cr-C Ceramic Coating Added Alloy Powder
Authors: Liu Jun Bo , Wang Li Mei , Jiang Jun Sheng
Published: February 2011

Fe-Cr-C ceramic composite coating was fabricated on substrate of Q235 steel by submerged-arc welding process added alloy powder using the material of chromium powder, iron powder, colloid graphite powder and H08 welding wire. Microstructure and wear properties of the composite coating were investigated by means of X-ray diffraction (XRD), scanning electron micrograph (SEM), energy dispersive X-ray analysis (EDS) and microhardness tester. wearresisting property of the coating was tested at room temperature and dry sliding wear conditions. Results show that the composite coating consists of (Cr,Fe)7C3 eutectic phase and austenite. There are many dendrite crystal structure in the coating, and most of the dendrite crystal are parallel, pointing to the surface of the coating. The wear mass loss of the base body Q235 steel is 10 times higher as that of the composite coating. The coating has excellent wear-resisting property because there are many eutectic carbide (Cr,Fe)7C3. It can increase wear resisting property of the coating that the austenite could occurr strain and induced martensite in the coating during wear.
Experimental Research on Making Aerated Concrete by Petroleum Coke Desulfuration Residue
Authors: Li Qiu Yi , Zhang Ping , Gao Song , Du Hui
Published: February 2011

Petroleum coke desulfuration residue, from combustion desulfuration of high sulfur petroleum coke, presents drying powdery and a favorable cementing performance. Lime and gypsum are replaced by petroleum coke desulfuration residue to produce aerated concrete in this research. The experimental results indicate that products made of high-sulfur petroleum coke desulfuration residue satisfy the requirements in national code of autoclaved aerated concrete [1] (GB11968-2006) and has better performance than traditional lime aerated concrete products. Consequently, the application of high-sulfur petroleum coke desulfuration residue in aerated concrete broadens the resourcelized utilization of petroleum coke desulfuration residue, and solves the scarcity of building materials resources. It ought to have expansive application prospect because of remarkable economic, social, and environmental benefits.
Casting of Clad Strip by a Roll Caster
Authors: Nakamura R. , Haga Toshio , Tsuge H. , Kumai S. , Watari H.
Published: February 2011

The three layers clad strip was fabricated by a tandem positioned vertical type twin roll casters. The effect of the casting conditions of the overlay strip on the interface between the base strip and the overlay strip was investigated. The temperature of the molten metal, roll-load and solidification length were chosen as the casting conditions. Base strip was AA8079 and overlay strip was AA6022. The proper melt temperature of the overlay strip was above the liquidus line of the base strip. The proper roll-load, which was lower than rolling, was existed. There was not clearance at the interface when the solidification length was appropriate.
Fabrication of LSGM Thin Film Electrolyte on LSCM Anode by RF Magnetron Sputtering for IT-SOFC
Authors: Yu Jie , Ma Wen Hui , Lin Hang Sheng , Sun Hong Yan , Chen Xiu Hua , Yang Bin
Published: February 2011

La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM) thin film electrolytes were fabricated on La0.7Sr0.3Cr0.5Mn0.5O3-δ (LSCM) porous anodes by radio-frequency (RF) magnetron sputtering. The formation and microstructure of LSGM thin films were characterized by X-ray diffraction(XRD) and scanning electron microscopy (SEM). The effects of different sputtering conditions, such as Ar gas pressure, substrate temperature and sputtering power, on the performance of LSGM electrolyte film were estimated. Dense LSGM thin film electrolytes with thickness of about 2μm, which are compatible with LSCM-based anodes and without crack, have been successfully fabricated on LSCM-based anode supports by RF magnetron sputtering when sputtering power density is 5.2W·cm-2, Ar gas pressure is 5Pa and substrate temperature is 300°C. It is found that high sputtering power density and high Ar gas pressure, as well as high substrate temperature, are beneficial to deposition of dense electrolyte thin film, close bonding of electrolyte thin film with anode substrate, and formation of large three phase boundaries between anode and electrolyte.
A Study of Nuclear of Interest Martensitic Steels and FeCr ODS Alloys Using Small Angle Neutron Scattering
Authors: Mathon Marie Helene , de Carlan Yann , Zhong Sheng Yi , Henry Jean , Olier Patrick , Klosek Vincent , Ji Vincent
Published: February 2011

Small Angle Neutron Scattering (SANS) technique allows to characterize at a nanoscale the microstructure of the ferritic martensitic steels and ODS FeCr alloys which are candidates for the internal structures of future nuclear reactors. Firstly, the microstructure evolution induced by neutron irradiation at high dose in conventional and Reduced Activation Fe9%Cr martensitic steels is presented. Then, a SANS study of Oxide Dispersion Strengthened (ODS) alloys is also presented. The main objective is to control the nano-size oxide particles at the various stages of the fabrication process.
Surface Modification and Preparation of High Purity Nanometer Magnesium Hydroxide Using Impinging Stream
Authors: Zhao Jian Hai , Lai Yan Ping
Published: February 2011

High purity nanometer magnesium hydroxide is produced by impinging stream reaction crystallization method using bischofite as feedstock. Effects of operation conditions on the impinging stream of Mg (OH)2 are reported and the control factors of purity are confirmed. The morphology of the powder was characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Result shows that purity of Mg (OH)2 can reach 99% and the mean size of crystal is 13.5nm. Surface modification of nano-sized magnesium hydroxide using four surface modifiers such as sodium steatite, sodium laurylsulfonate, sodium oleate and sodium silicate were investigated in this paper. The modified magnesium hydroxide has smaller particle size, larger powder contact angle, slower sedimentation velocity, the less in-oil capacity than unmodified sample
Phase Equilibria of Boron in Metallurgical Grade Silicon at 1300°C
Authors: Wu Ji Jun , Ma Wen Hui , Yang Bin , Liu Da Chun , Dai Yong Nian
Published: February 2011

The diffusion layer and melt of silicon-boron are respectively obtained after quenched in water at 1300 oC by using metallurgical grade silicon (MG-Si) powder and amorphous boron powder. The phase equilibria for boron in MG-Si have been investigated by using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The back scattered electron (BSE) image of diffusion layer displays the intermediate phase SiB4 in silicon-boron phase band, and the XRD results also indicate that SiB4 exists in silicon-boron diffusion layer at 1300 oC. It is inferred that the intermediate phase SiB4 is formed by the reaction (Si) + SiB6 ↔ SiB4 according to the equilibrium composition of Si/B=4/1 as quantified by Energy Dispersive Spectroscopy.
Manufacturing AISI316L Components via Selective Laser Melting Coupled with Hot Isostatic Pressing
Authors: Wang Zhi Gang , Shi Yu Sheng , Li Rui Di , Wei Qing Song , Liu Jin Hui
Published: February 2011

Selective laser melting (SLMing) is a new advanced material processing technology which is used in fabricating parts with complex shape. Hot isostatic pressing (HIPing) is a manufacture technology which forms parts by imposing high heat and pressure on metal powders or semi-manufactured parts. Considering the advantages of both the technologies, they can be combined to produce higher-quality parts free from the limitation of the shape of parts. AISI316L stainless steel is widely used in manufacturing varies of complex metal parts. In this research, three AISI316L stainless steel samples with different relative densities were acquired by controlling the fabricating parameters in SLM. The SEM and optical microscopy analysis were employed to characterize the relative density, microstructure, deformation by comparing the differences between SLM samples and SLM-HIPped samples. In addition, the influence of HIP process on microstructures of samples in different laser fabricating parameters was investigated by analyzing the mechanisms of SLM and HIP. The results show that HIP can close vacuum crack and pore, consequently, the relative density of SLM samples increases after HIP, making the property of the samples improved and microstructure better-distributed. Moreover, the increment of relative density under the same HIP condition is also discussed.
Numerical Simulation of Temperature Field during Laser Deep Penetration Welding
Authors: Wang Ren Ping , Lei Y.P.
Published: February 2011

A computational analysis is achieved during laser deep penetration welding. Multiple reflection and absorption are implemented simultaneously with the ray tracing technique in the keyhole. With all the governing equations including continuity, momentum and energy equation, the VOF method is adopted to trace the free surface of the molten pool. Temperature field is achieved by numerical simulation. The laser keyhole welding experiments on 304 stainless steel sheet showed that the computational results agree well with experimental results.
Removal of Iron from Metallurgical Grade Silicon with Pressure Leaching
Authors: Xie Ke Qiang , Yu Zhan Liang , Ma Wen Hui , Zhou Yang , Dai Yong Nian
Published: February 2011

In this paper, removal of iron from metallurgical grade silicon with pressure leaching is carried out. We investigated the factors such as the concentration of hydrochloric, particle size of raw material ground, temperature, pressure and reaction time, which influenced on the removal of iron. The results show that the optimum operating conditions for pressure leaching in hydrochloride are: acid concentration 4 mol/L, diameter for raw material less than 50 μm, leaching temperature 160 0C，leaching pressure 2.0 MPa, leaching time 2.0 h. The content of iron residual in MG-Si powder was reduced to about 200 ppmw. The removal efficiency of iron is up to 90.90 %.
Constitutive Inequalities for the Damage of Elastic-Brittle Materials
Authors: He Qi Chang , Zhou J.Z.
Published: February 2011

Starting from the requirement that the principle of determinism be satisfied, two constitutive inequalities are derived for one-dimensional strain- and stress-based continuum damage models. The one-dimensional constitutive inequality corresponding to the strain-based formulation turns out to be much less restrictive than the one associated to the stress-based formulation and is extended to the three-dimensional case. This extension gives a general constitutive inequality for the damage of elastic-brittle materials.
η Phase Formation Mechanism at Cemented Carbide YG30/Steel 1045 Joints during Tungsten-Inert-Gas Arc Welding
Authors: Zhao Xiu Juan , Liu Peng Tao , Chen Chun Huan , Yang De Xin , Kohsuke Tagashira
Published: February 2011

Cemented carbide YG30 and steel 1045 were welded with various Ni-Fe-C filling alloys via the Cemented carbide YG30 and steel 1045 were welded with various Ni-Fe-C filling alloys via the tungsten-inert-gas (TIG) arc welding. η phase formation at the welding joints was investigated via scanning electronic microscope (SEM), transmission electronic microscope (TEM) coupled with selected diffraction, and electron probe microanalysis methods. η phases in three different morphologies were identified and they appeared to form in different mechanisms. The η phase formed at the heat-affected zone (HAZ) exhibited a similar size to that of WC particles and its formation was mainly attributed to the inter diffusion among W, C and Fe, Co, Ni in solid-state γ phase. The large-size η phase near the interface between YG30 and weld bead was due to the coarsening of tiny η grains in the liquid weld bead. The small-size η phase was formed via precipitation from the γ phase during cooling. The η phase formation could be controlled by optimization of C and/or Ni concentration in the filling alloys.
Atomistic Simulation of Deformation Behavior at a Crack Tip in Magnesium Single Crystal
Authors: Jiang Li Ming , Guo Ya Fang
Published: February 2011

The mechanisms of low-temperature deformation around a crack tip in a hexagonally closed-packed (hcp) magnesium single crystal have been studied by molecular dynamics simulations. In our simulation a {1010} < 12 10 > model I (opening model) crack is selected. The results indicate that slip on the basal plane is activated due to the shear stress at the crack tip. Thus shear banding caused by a successive slip of the basal planes is the main deformation way for this type of crack.
Oxygen Reduction Reaction on Carbon Supported Ruthenium-Based Electrocatalysts in PEMFC
Authors: Zhong He Xiang , Zhang Hua Min , Wang Mei Ri
Published: February 2011

The ruthenium-based electrocatalysts supported on carbon black were prepared by the decarbonylation of the transition metal carbonyl with the 1,6-hexanediol as the solvent. The catalysts were characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution TEM (HRTEM). The electrochemical behaviours of the catalysts were investigated by cyclic voltammetry (CV) and rotating disk electrode (RDE) measurements in 0.5 M H2SO4 solution. The catalysts demonstrate attractive catalytic activity towards the ORR. The catalyst is expected to be promising alternative non-Pt electrocatalysts for PEMFC.
Manufacture of Aluminum Nanocomposites: A Critical Review
Authors: Borgonovo Cecilia , Apelian Diran
Published: February 2011

In the last two decades, metal matrix nanocomposites have witnessed tremendous growth. Particulate-reinforced nanocomposites have been extensively employed in the automotive industry for their capability to withstand high temperature and pressure conditions. Several manufacturing approaches have been used to fabricate them. Non-homogeneous particle dispersion and poor interface bonding are the main drawbacks of conventional manufacturing techniques. A critical review of nanocomposite manufacturing processes is presented; the distinction between ex-situ and in-situ processes is discussed in some detail. Moreover, in-situ gas/liquid processes are elaborated and their advantages are discussed. The thermodynamics and kinetics of the reaction between the precursor gas and the liquid metal have been analyzed and their role on particle formation studied. This critical review will provide the reader with an overview of nanocomposite manufacturing methods along with a clear understanding of advantages and disadvantages.
Effect of Mechanical Mould Vibration on Solidification Behaviour and Microstructure of A360-SiCp Metal-Matrix Composites
Authors: Timelli Giulio , Della Corte Emilia , Bonollo Franco
Published: February 2011

In this work the microstructural evolution of an A360 alloy reinforced with 10vol.% SiC particulate is described. During the material solidification, mechanical vibration, in the range of 0-41 times the gravity acceleration, g, has been applied to a steel die. It has been observed that vibrations can promote a quite homogeneous SiC dispersion on macroscopic scale. On the other hand, by using too high vibrations’ intensity, segregation phenomena have been pointed out in the castings. Furthermore, it has been evidenced that the reinforcement distribution is influenced by mechanical entrapment of the particles at grain boundaries and in the interdendritic channel. The metallographic analysis has emphasized a finer microstructure with increasing vibrations’ intensity. By comparing simulated and experimental temperature curves of the mould in the different cases, different HTC made the best fit. By increasing the vibrations’ intensity, the HTC increases in the temperature range of solidification of the composite.
Production and Characterization of Aluminum Iron Powder Composites with Ferromagnetic Properties
Authors: Amadori Stefano , Bonetti Ennio , Campari Enrico G. , Pasquini Luca
Published: February 2011

Composites made from compacted powders blends of Al with different Fe contents were produced and characterised with respect to mechanical and induction heating properties. Mechanical spectroscopy and hardness measurements were employed to follow the evolution of Young modulus and internal friction after ageing. It was found that above a critical iron content (>30% of the volume) a percolation network of Fe grains is obtained inside the specimen and the induction heating characteristics become comparable with those of ferritic steel samples.
Micro-Chemistry and Mechanical Behaviour of Ti6Al4V-SiCf Composite Produced by HIP for Aeronautical Applications
Authors: Deodati Paolo , Donnini Riccardo , Kaciulis Saulius , Kazemian-Abyaneh Majid , Mezzi Alessio , Montanari Roberto , Testani Claudio , Ucciardello Nadia
Published: February 2011

The paper reports the results of an extensive characterization of the Ti6Al4V-SiCfcomposite produced by hot isostatic pressing (HIP) to assess its capability to withstand the in-service conditions of turbine blades operating at middle temperatures in aeronautical engines. The microstructure of composite, in as-fabricated condition and after long-term heat treatments (up to 1,000 hours) in the temperature range 673-873 K, has been investigated by means of different techniques. Particular attention was paid to the micro-chemical evolution of fibre-matrix interface which is scarcely affected also by the most severe heat treatments examined here. This leads to stable mechanical properties as evidenced by hardness, tensile and FIMEC instrumented indentation tests. Therefore, the composite can operate at the maximum temperature (873 K) foreseen for its aeronautical applications without remarkable modifications of its microstructure and degradation of mechanical properties. The mechanical characterization has been completed by internal friction and dynamic modulus measurements carried out both at constant and increasing temperature, from 80 to 1173 K.
Dry Sliding Behaviour of Peo (Plasma Electrolytic Oxidation) Treated AA 2618/20% Al2O3p Composite
Authors: Ceschini Lorella , Martini Carla , Sambogna Giuliano , Tarterini Fabrizio
Published: February 2011

The present study focuses on the influence of the PEO (Plasma Electrolytic Oxidation) treatment on the tribological behaviour of the AA2618/20 % vol. Al2O3p composite, dry sliding against induction hardened UNI C55 steel. Particle-reinforced Al based composites offer a higher wear resistance by comparison with the corresponding unreinforced alloys, however, the presence of critical loads and/or velocities which lead to transition towards severe wear regime, was often observed. In such conditions, the composite can show higher wear rates than those of unreinforced alloys. For this reason, surface modifications, such as PEO, might contribute to improve wear resistance. In this paper, topography, microstructure, phase constitution and surface hardness of the PEO-treated composite were investigated and its tribological behaviour was studied by dry sliding tests using a block-on-ring tribometer. The results were compared with those from the uncoated composite, demonstrating a very positive effect of the PEO treatment, which moved transitions from mild to severe wear towards more severe test conditions, in terms of both load and velocity.
Friction Welding of Particle Reinforced Aluminium Based Composites
Authors: Ceschini Lorella , Morri Alessandro , Rotundo Fabio
Published: February 2011

The widespread use of metal matrix composites (MMC) is often limited due to the difficulties related to their joining by means of traditional fusion welding processes. The aim of this work was to evaluate the effect on microstructure and mechanical properties (hardness and tensile strength) of two different friction welding techniques used for joining two Al-based metal matrix composites. In particular, Friction Stir Welding was applied to a 6061 (Al-Mg-Si) alloy matrix, reinforced with 20vol.% of Al2O3particles (W6A20A), while Linear Friction Welding was applied to a 2124 (Al-Cu-Mg) alloy matrix reinforced with 25vol.% of SiC particles (AMC225xe). Both the welding processes permitted to obtain substantially defect-free joints, whose microstructures was found to be dependent on both the initial microstructure of the composites and the welding processes. Hardness decrease was in the order of 40% for the FSW joint and of 10% for the LFW joint, mainly due to overaging of the matrix induced by the frictional heating, while the joint efficiency in respect to the ultimate tensile strength was 72% and 82%, respectively. Elongation to failure increased in the FSW joint due to coarsening of precipitates, whereas it decreased in the LFW joints due to the fibrosity in the thermomechanically altered zone. Fracture surface analysis showed good matrix/reinforcement interface for both composites.