Started in 1985 Semimonthly
ISSN 1005-0302
CN 21-1315/TG
Impact factor:6.155

The journal has been awarded the excellent periodical in China, and its articles are covered by SCI, EI, CA, SA, JST, RJ, CSA, MA, EMA, AIA etc., PASCAL web. ISI web of Science,SCOPUS.

Current Issue
 28 September 2005, Volume 21 Issue 05 Previous Issue    Next Issue
Research Articles
 Select A Novel Hydrothermal Synthesis of Single Crystalline PbS Nanorods and Their Characterization Hongliang ZHU, Deren YANG, Hui ZHANG J. Mater. Sci. Technol., 2005, 21 (05): 609-612.  Abstract   HTML   PDF (0KB) Lead sulfide (PbS) nanorods with a high aspect ratio were prepared by a novel thioglycolic acid assisted hydrothermal method. X-ray diffraction and transmission electron microscopy revealed that the product was rod-like PbS with cubic rock-salt structure. Further characterizations by selected area electron diffraction and high-resolution transmission electron microscopy showed that the PbS nanorods were single crystalline in nature. Furthermore, the mechanism and critical factors for the hydrothermal synthesis of the nanorods have been discussed.
 Select Reflections on the Mechanism of Calcium Phosphate Nucleation on Titanium in Simulated Body Fluids F.T.Cheng J. Mater. Sci. Technol., 2005, 21 (05): 613-617.  Abstract   HTML   PDF (292KB) The results and main findings of studies reported in the literature in relation to the deposition of calcium phosphate on Ti in simulated body fluids are summarized. The effects of the surface hydroxyl groups and the sign of surface charge on the nucleation of calcium phosphate are reviewed. One major controversy among the conclusions of different studies is the order of adsorption of the calcium ions and the phosphate ions in the initial stage of immersion. A simple model based on the amphoteric nature of the hydroxyl groups on Ti is proposed in an attempt to delineate the nucleation process for calcium phosphate on Ti in simulated body fluids. HPO42- ions interact with the hydroxyl groups via ion exchange and/or electrostatic attraction, and Ca2+ ions, via electrostatic attraction only. There is no preferential order of adsorption. Seemingly inconsistent results in different studies possibly arise from different prior treatments of the samples, which affect the adsorption properties.
 Select Solid State Synthesis and Thermoelectric Properties of Mg-Si-Ge System Renbo SONG, Yazheng LIU, Tatsuhiko AIZAWA J. Mater. Sci. Technol., 2005, 21 (05): 618-622.  Abstract   HTML   PDF (1488KB) Thermoelectric materials, Mg2Si1-xGex(x=0, 0.2, 0.4, 0.6, 0.8, 1), have been prepared by bulk mechanical alloying (BMA) and hot pressing (HP). The electrical conductivity, Seebeck coefficient and thermal conductivity were measured from room temperature up to about 700 K. The electrical conductivity of all the samples increases with increasing temperature, while the Seebeck coefficient and thermal conductivity decrease with increasing temperature. Mg2Si and Mg2Si0.8Ge0.2 possess negative type of conductivity, while for other compounds it is positive. At the same time, the effect of hot processing condition on thermoelectric properties was also investigated. The maximum figure of merit of Mg2Si0.6Ge0.4 was obtained with the processing parameter of BMA at 600 cycles and hot pressing at 773 K and 1 GPa for 1 h.
 Select Effect of Equal Channel Angular Extrusion on the Microstructures and Properties of Two Extruded Al-Mg-Si Alloys M.Cai, G.W.Lorimer J. Mater. Sci. Technol., 2005, 21 (05): 623-629.  Abstract   HTML   PDF (1456KB) The effect of equal channel angular extrusion (ECAE) on the microstructure of two Al-Mg-Si extrusion alloys was investigated by high resolution electron backscattered diffraction (EBSD) using a field emission gun scanning electron microscope (FEG-SEM) and a transmission electron microscope (TEM). Two contrasting alloys: a dilute alloy, based on alloy 6061 and a concentrated alloy, based on alloy 6069 were employed for this research. It has been found that prior ECAE to extrusion promotes high angle grain boundaries (HAGBs) in the extrusions, and the increase in HAGBs ratio is due to the large shear deformation involved in the process of ECAE. Tensile testing results show that a further ageing treatment strengthens the alloys after extrusion and the ECAE processed extrusions are more ductile than conventional extrusions.
 Select Effect of Small Addition of Sc on the Microstructural Evolution in Al-15Ag Alloy Zhiguo CHEN, Ziqiao ZHENG, Simon P.Ringer J. Mater. Sci. Technol., 2005, 21 (05): 630-634.  Abstract   HTML   PDF (4624KB) The effect of small addition of Sc on the microstructural evolution in Al-15Ag alloy was investigated by Monte Carlo simulation and transmission electron microscopy (TEM). Monte Carlo simulation results indicate that Ag clustering is suppressed by the addition of Sc during the initial ageing stage, and there is a little chemical repulsion between Ag atoms and Sc atoms. TEM observations show that the morphology of γ' precipitation can be modified by the small addition of Sc, which does result in a refinement of γ' precipitates in Al-15Ag-0.2Sc. The mechanism by which trace Sc affect the microstructure is to reduce the ledge density of γ' precipitates.
 Select Mechanical Properties of DS NiAl/Cr(Mo) Alloys with Low Addition of Hf for High-temperature Applications Xinghao DU, Jianting GUO J. Mater. Sci. Technol., 2005, 21 (05): 635-640.  Abstract   HTML   PDF (1038KB) A multiphase NiAl-28Cr-5.85Mo-0.15Hf alloy, which was directionally solidified (DS) in an Al2O3-SiO2 mold by standard Bridgman method and then underwent prolonged solution and aging treatment was prepared. The microstructure, tensile properties as well as tensile creep of the heat-treated alloy at different temperatures were studied. The alloy was composed of NiAl, Cr(Mo) and Hf-rich phase and small amount of fine Heusler phase (Ni2AlHf). Although the present alloy exhibited high tensile strength at low temperature, it was weaker than that of system with high content Hf but still stronger than that of many NiAl-based alloys at high temperatures. The fracture toughness is lower than that of DS NiAl-28Cr-6Mo alloy. Nevertheless, advantageous effects on the mechanical properties, $i.e$. the decrease in brittle-to-ductile transition temperature (BDTT) were obtained for the low content of Hf. The obtained creep curves exhibit conventional shape: a short primary creep and long accelerated creep stages. The rupture properties of the heat-treated alloy follow the Monkman-Grant relationship, which exhibits similar creep behavior to that of NiAl/Cr(Mo) system with high Hf content.
 Select BDT and Creep Behaviors of NiAl-25 at. pct Cr Alloy at Various Temperatures Guangye ZHANG, Xinghao DU, Jianting GUO, Hengqiang YE J. Mater. Sci. Technol., 2005, 21 (05): 641-646.  Abstract   HTML   PDF (1367KB) Brittle-to-ductile transition (BDT) behavior and creep behavior of extruded NiAl-25Cr alloy at elevated temperatures were investigated. The results reveal that the alloy exhibits obvious BDT behavior with the increase in temperature and BDT temperature (BDTT) is sensitive to initial strain rate. When the initial strain rate increases by two orders of magnitude, BDTT has an increase of approximate 80 K. The creep data in the temperature range of 1073～1123 K reveal two distinct regions of creep behavior in this material. At lower temperature, the creep characteristics are consistent with structural controlled creep process where creep deformation is controlled by dislocation climb. At higher temperature, the creep characteristics are consistent with mobility-controlled deformation where viscous glide of dislocations controls creep. The apparent activation energy determined by creep in both regions exceeds the value for lattice self-diffusion in NiAl by a considerable amount. This can be explained in terms of the simultaneous deformation of second phase particles (γ'-Ni3Al and α-Cr phase) along NiAl matrix during creep.
 Select Manufacturing Titanium Metal Matrix Composites by Consolidating Matrix Coated Fibres Hua-Xin PENG J. Mater. Sci. Technol., 2005, 21 (05): 647-651.  Abstract   HTML   PDF (510KB) Titanium metal matrix composites (TiMMCs) reinforced by continuous silicon carbide fibres are being developed for aerospace applications. TiMMCs manufactured by the consolidation of matrix-coated fibre (MCF) method offer optimum properties because of the resulting uniform fibre distribution, minimum fibre damage and fibre volume fraction control. In this paper, the consolidation of Ti-6Al-4V matrix-coated SiC fibres during vacuum hot pressing has been investigated. Experiments were carried out on multi-ply MCFs under vacuum hot pressing (VHP). In contrast to most of existing studies, the fibre arrangement has been carefully controlled either in square or hexagonal arrays throughout the consolidated sample. This has enabled the dynamic consolidation behaviour of MCFs to be demonstrated by eliminating the fibre re-arrangement during the VHP process. The microstructural evolution of the matrix coating was reported and the deformation mechanisms involved were discussed.
 Select In-situ TiCP/Al Composites Prepared by TE/QP Method Mingzhen MA, Riping LIU, Hongli ZHAO, Yifa YU J. Mater. Sci. Technol., 2005, 21 (05): 652-656.  Abstract   HTML   PDF (871KB) An in-situ TiCP/Al composite was prepared by a thermal explosion/quick pressure method (TE/QP). The effect of Al content on the reaction temperature as well as the reaction rate has been studied. Phase constituents and the microstructure of the composites and the particle size of the reinforcement were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results have shown that TiCp/Al composite with 40～70 vol. pct TiC particle reinforcement and high relative density can be directly obtained by TE/QP. TiC is the only reaction product when Al content in Al-Ti-C system is no more than 60 vol. pct, but Al3Ti phase will also form when Al content is more than 60 vol. pct. Increasing Al content prolongs the initial reaction time, reduces the highest reaction temperature and the reaction rate, and decreases the size of TiC particles. In addition, the microstructure of TiCp/Al composite and the structure of interface between TiCp and Al are studied using SEM and transmission electron microscopy (TEM). The results show that the in-situ synthesized TiC particle has fcc cubic structure. The orientation between TiC particles and Al matrix can be described as ( )Al//( )TiC and [ ]Al//[011] TiC. Results of the mechanical property tests reveal that the ultimate strength (σ) and modulus (E) are 687~MPa and 142 GPa respectively when the Al content is 40 vol. pct. On contrary,δ elongation increases by 3.2% with increasing Al content.
 Select Interfacial Shear Strength Measurements of SiC Fiber-Reinforced Titanium Composites Yanhua LI, Nanlin SHI, Dezhi ZHANG, Rui YANG J. Mater. Sci. Technol., 2005, 21 (05): 657-660.  Abstract   HTML   PDF (286KB) A continuous loading push-out test technique was used to measure the interfacial shear strength of SiC fiber reinforced Ti matrix composites. The interfacial shear strength of samples as-fabricated and after heat exposed at 700 and 800℃ for 50 h was successfully determined. It has been found that the interfacial shear strength of the specimen exposed at 700℃ was higher than that of as-prepared and exposed samples at 800℃. The shear strength of the as-prepared samples was about 112.45 MPa, and increased to about 153.77 MPa after heat-treating at 700℃ for 50 h, but decreased to 133.11 MPa after treating at 800℃ for 50 h. Scanning electron microscope (SEM) was used to investigate the interfacial morphology of the samples. The brittle phase was the main products of interface for samples exposed at 800℃, and the interface was easily peeled off.
 Select Electrochemical Formation of Polypyrrole-carboxymethylcellulose Conducting Polymer Composite Films H.N.M.Ekramul Mahmud, Anuar Kassim, Zulkarnain Zainal, Wan Mahmood Mat Yunus J. Mater. Sci. Technol., 2005, 21 (05): 661-665.  Abstract   HTML   PDF (1181KB) The electrochemical preparation of polypyrrole-carboxymethylcellulose (PPY-CMC) conducting polymer composite films on indium tin oxide (ITO) glass electrode from an aqueous solution containing pyrrole monomer, $p$-toluenesulfonate electrolyte and carboxymethylcellulose insulating polymer is reported. The characterization by Fourier transform infrared spectroscopy (FT-IR) shows that carboxymethylcellulose (CMC) has been successfully incorporated into polypyrrole structure forming PPY-CMC polymer composite films. The conductivity of the prepared composite films was found to increase with increaseing CMC concentration in pyrrole solution. The optical microscopic results show the influence of CMC concentration in the pyrrole solution over the morphological changes of the prepared films. The dynamic mechanical analysis (DMA) on the prepared PPY-CMC film reveals the higher plastic property of the PPY-CMC composite film.
 Select Sliding Wear Behavior of Plasma Sprayed Zirconia Coating on Cast Aluminum against Silicon Carbide Ceramic Thuong-Hien LE, Young-Hun, Seock-Sam KIM J. Mater. Sci. Technol., 2005, 21 (05): 666-670.  Abstract   HTML   PDF (1214KB) The sliding wear behaviors of ZrO2-22 wt pct MgO (MZ) and ZrO2-8 wt pct Y2O3 (YZ) coatings deposited on a cast aluminum alloy with bond layer (NiCrCoAlY) by plasma spray were investigated under dry test conditions at room temperature. Under all load conditions, the wear mechanisms of the MZ and YZ coatings were almost the same. The material transfer and pullout were involved in the wear process of the studied coatings under the test conditions. The wear rate of the MZ coating was less than that of the YZ coating. While increasing the normal load, the wear rates of the MZ and YZ coatings increased. SEM was used to examine the worn surfaces and to elucidate likely wear mechanisms. Energy dispersive X-ray spectroscopy (EDX) analysis of the worn surfaces indicated that material transfer occurred in the direction from the SiC ball to the disk. Fracture toughness had a significant influence on the wear performance of the coatings. It was suggested that the material transfer played an important role in the wear behavior.
 Select Characterization and Tribological Behavior of Octadecene, Dodecene and Undecenoic Acid Films on Si Substrate Jinfang ZHOU, Shengrong YANG J. Mater. Sci. Technol., 2005, 21 (05): 671-674.  Abstract   HTML   PDF (613KB) The films of octadecene, dodecene, and undecenoic acid were prepared on H-terminated Si surface in the presence of ultraviolet irradiation. The resulted films were characterized with water-contact angle measurement and infrared spectroscopy. The friction-reducing behavior of the prepared films was examined on a static-dynamic friction coefficient measurement apparatus and on an atomic force microscope. It was found that all the reacted films on the Si substrate showed good friction-reducing ability; especially, the film of the octadecene exhibited the best friction-reducing ability. This was attributed to the transfer of the reacted films onto the counter face with formation of a transfer film on the counterpart surface, which led to the transformation of the sliding between the reacted films and the hard ceramic to that between the reacted films and its transfer film on the counterpart surface. The macroscopic and microscopic friction behaviors of the prepared films were dependent on their molecular chain lengths. Thus the octadecene reacted film with the highest degree of ordering arrangement showed the best friction-reducing and antiwear abilities in sliding against Si3N4.
 Select Physicochemical Properties of Nanocrystallite Copper Ferrite Prepared by a Novel Self Flash Combustion of Acetate Precursors M.H.Khedr, A.A.Farghali J. Mater. Sci. Technol., 2005, 21 (05): 675-680.  Abstract   HTML   PDF (2153KB) Copper ferrite, CuFe2O4, one of the important ferrites due to its interesting electrical, magnetic and structural properties, is obtained by a novel self flash combustion of a homogeneous mixture of one mole copper acetate monohydrate, Cu(CH3COO)2•H2O, and two moles of iron (III) acetate basic, Fe(CHCOO)2•OH. Nanocrystalite (89 nm) copper ferrite (less than 100%) is obtained at lower temperatures, whereas 100% copper ferrite is obtained after calcination at 1000℃. Thermal analysis (TG and DTA), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), photo microscopy, magnetic and porosity measurements have been carried out for the specimens obtained after calcinations at 700, 800, 900 and 1000℃ to characterize the conversion efficiency of the powder precursors to copper ferrite. It was found that increasing temperature leads to great improvement in the magnetic properties. By increasing calcination temperature from 700～1000℃ saturation magnetic flux density (Bs) increased from 17.8 to 40.8 emu/g, while remnant magnetic flux density (Br) increased from 10.1 to 17.11 emu/g.
 Select Effect of Process Parameters on Porosity in Aluminum Lost Foam Process Kiyoung KIM, Kyongwhoan LEE J. Mater. Sci. Technol., 2005, 21 (05): 681-685.  Abstract   HTML   PDF (634KB) Porosity is a main defect in aluminum alloy castings, which is also thought to be severe in aluminum alloy castings produced by lost foam process due to the pyrolysis of the polystyrene foam pattern during pouring. Fundamental experiments were carried out to evaluate the effect of process parameters such as the melt treatment, the cooling rate and the density of expanded polystyrene (EPS) foam on porosity in A356.2 bar casting. The effect of melt treatment including degassing and refining was investigated. The effect of cooling rate was also evaluated by changing the mold packing material such as the silica sand, the zircon sand and the steel shots. Gas entrapment due to the turbulent metal flow during mold filling in conventional molding process results in porosity. Mold filling sequence in lost foam process is different from that in conventional molding process. The effect of molten metal flow was estimated by comparing the density of the casting by conventional sodium silicate molding with that by lost foam process. Density measurement was conducted to analyze the extent of porosity in the casting. Source of the porosity in lost foam process can be divided into two factors, i.e. turbulence in molten metal flow and entraining residue or gas from the pattern during pouring.
 Select Influence of Carbon Nanofiber Addition on Mechanical Properties and Crystallization Behavior of Polypropylene Xin TONG, Yong CHEN, Huiming CHENG J. Mater. Sci. Technol., 2005, 21 (05): 686-690.  Abstract   HTML   PDF (419KB) Carbon nanofiber (CNF)-reinforced polypropylene (CNF/PP) composites with different CNF contents were prepared by melt mixing, and the mechanical properties and crystallization behavior of the CNF/PP composites obtained were investigated. It was found that the tensile modulus of the composites was increased with the addition of CNFs, but their elongation at break and fracture strain energy were decreased, while the tensile strength of the composites was firstly increased and then decreased due to the agglomeration of CNFs at higher loading. Nonisothermal crystallization analysis showed that the CNFs played a role as nucleating agent in PP matrix, which led to increment in the crystallization rate and the degree of crystallinity of PP. Moreover, X-ray diffraction studies showed that the CNFs incorporated in the PP matrix favored the growth of (040)-oriented PP crystals. With the increase in the CNF content, the nucleating and orientation roles of the CNFs were obviously enhanced.
 Select Effect of Coarse Aggregate Size on Relationship between Stress and Crack Opening in Normal and High Strength Concretes Jun ZHANG, Qian LIU, Lin WANG J. Mater. Sci. Technol., 2005, 21 (05): 691-700.  Abstract   HTML   PDF (13064KB) Fine and coarse aggregates play an important role in the fracture of concrete. However, quantitative information available on the effect of the coarse aggregate size on the fracture properties of concrete is still limited. In the present paper, the effect of coarse aggregate size (single grade of 5～10, 10～16, 16～20 and 20～25 mm) on stress-crack opening (σ-ω) relation in normal and high strength concretes (compressive strength of 40 and 80 MPa, respectively) was studied. The investigation was based on three-point bending tests implemented by fictitious crack analysis. The result shows that coarse aggregate size and cement matrix strength significantly influence the shape ofσ-ω curve. For a given total aggregate content, in normal strength concrete, smaller size of aggregate leads to a high tensile strength and a sharp stress drop after the peak stress. The smaller the coarse aggregate, the steeper the σ-ωcurve. By contrast, in high strength concrete, the effect of aggregate size on σ-ω relation almost vanishes. A similar σ-ω relation is obtained for the concrete except for the case of 20～25 mm coarse aggregate size. The stress drop after the peak stress is more significant for high strength concrete than that for normal strength concrete. Meanwhile, the smaller the coarse aggregate size, the higher the flexural strength. Fracture energy and characteristic length increase with increasing coarse aggregate size in both normal and high strength concretes.
 Select Effect of Auxiliary Gases on Combustion Synthesis of Si3N4 Weiping SHEN, Fei WANG, Zhuohui WU, Changchun GE J. Mater. Sci. Technol., 2005, 21 (05): 701-704.  Abstract   HTML   PDF (531KB) This paper presents results of combustion synthesis (Self-Propagating High Temperature Synthesis, SHS) of Si3N4 under nitrogen with argon, hydrogen or ammonia. Higher percentages of α-Si3N4 content were obtained in large size cakes in SHS with hydrogen and ammonia than those with argon. Effect of the auxiliary gases for combustion synthesis of Si3N4 on α phase content, on phase transformation of α-Si3N4 to β-Si3N4 in SHS Si3N4 and on oxygen content in SHS Si3N4 were investigated.
 Select Thermodynamic Functions and Phase Transformation of Metal Nanocrystals Jinping GAO, Xiaoyan SONG, Jiuxing ZHANG, Keyong YANG, Xuemei LIU J. Mater. Sci. Technol., 2005, 21 (05): 705-709.  Abstract   HTML   PDF (507KB) A model to calculate the thermodynamic functions of the pure metal nanocrystals has been developed, with the consideration of the effects of both the interfaces and the crystal in the nano-grain interior. As an example, the enthalpy, entropy and Gibbs free energy, as functions of the excess free volume at interfaces, temperature and grain size, are calculated for the Co nanocrystals. Furthermore, the characteristics of β-Co→α-Co phase transformation are studied, and the transformation temperatures at different levels of grain size, as well as the critical grain sizes at different temperatures, are predicted. The calculation results show that, the nano-grained β-Co (fcc) is thermodynamically stable at temperatures much lower than that for the conventional coarse-grained materials, and may also stably exist at room temperature when the grain size is reduced to be small enough. The present model is verified by comparisons between the experimental findings and the theoretical predictions.
 Select Improvement of Toughness of Ultrahigh Strength Steel Aermet 100 Liuding WANG, Laizhu JIANG, Ming ZHU, Xiao LIU, Wangmin ZHOU J. Mater. Sci. Technol., 2005, 21 (05): 710-714.  Abstract   HTML   PDF (982KB) The influence of double aging on the microstructure and mechanical properties of ultrahigh strength steel Aermet 100 was analyzed. Under the double aging, there is no apparent decrease in the strength of steel. However, the impact fatigue life can be prolonged by 35.5% and dynamic fracture toughness be raised by 22.6% respectively, as compared with the normal aging. Based on the observation of microscopic structure, the physical mechanism of the prolongation of impact fatigue life and the enhancement of stability of the reverted austenite, AR, is analyzed further. The results show that this new technique is a breakthrough of combination optimization between strength and toughness for Aermet 100 steel. In the light of the current understanding on this subject, the volume fracture of soften and tough AR formed in process of heat preservation at higher temperature of double aging increases drastically. Moreover, during the treatment of lower temperature of double aging, the carbon separating from the martensitic ferrite will diffuse into AR, resulting that the martensitic brittleness decreases and the stability of AR increases.
 Select Synthesis of Poly (3-acetylpyrrolyl methine) with Azobenzene Side Groups and Study on Its Third-order Nonlinear Optical Property Zhigang ZHANG, Hongcai WU, Lingjie MENG, Wenhui YI J. Mater. Sci. Technol., 2005, 21 (05): 715-718.  Abstract   HTML   PDF (804KB) A novel soluble $\pi$-conjugated polymer, poly [(3-acetylpyrrole-2, 5-diyl) p-(N, N-dimethylamino) azobenzylidene] (PAPDMAABE), was synthesized by condensation of 3-acetylpyrrole with 4-aldehyde-4'-dimethylaminoazobenzene (ADMAA). The chemical structure of PAPDMAABE was characterized by Fourier transform infrared spectroscopy (FTIR), 1H-NMR, and UV-Vis-NIR spectra. Transmission electron microscope (TEM) analysis for PAPDMAABE indicates that part of PAPDMAABE is in crystal state, due to the short-range order of the polymer. Thermogravimetric analysis (TGA) curve shows that the polymer has good thermal stability and its decomposition temperature is 248℃. The optical band gap of PAPDMAABE obtained from the optical absorption spectrum is about 1.73 eV. The resonant third-order nonlinear optical property of PAPDMAABE at 532~nm was studied using degenerate four-wave mixing (DFWM) technique. The resonant third-order nonlinear optical susceptibility of the polymer is about 7.48×10-8 esu.
 Select Erosive Wear and Wear Mechanism of in situ TiCp/Fe Composites Zhaojing LIU, Zhiliang NING, Fengzhen LI, Xiurong YAO, Shanzhi REN J. Mater. Sci. Technol., 2005, 21 (05): 719-723.  Abstract   HTML   PDF (563KB) The base structure of in situ TiCp/Fe composites fabricated under industrial condition was changed by different heat treatments. Erosive wear tests were carried out and the results were compared with that of wear-resistant white cast iron. The results suggest that the wear resistance of the in situ TiCP/Fe composite is higher than that of wear-resistant white cast iron under the sand erosive wear condition. The wear mechanism of the wear-resistant white cast iron was a cycle process that base surface was worn and carbides were exposed, then carbides was broken and wear pits appeared. While the wear mechanism of in situ TiCP/Fe composite was a cycle process that base surface was worn and TiC grains were exposed and dropped. The wear resistance of in situ TiCP/Fe composite was lower than that of wear-resistant white cast iron under the slurry erosive wear condition. Under such circumstance, the material was not only undergone erosive wear but also electrochemistry erosion due to the contact with water in the medium. The wear behaviours can be a combination of two kinds of wear and the sand erosive wear is worse than slurry erosive wear.
 Select Carbothermic Reduction of Zinc Oxide Concentrate by Microwave Ali Saidi, Kamran Azari J. Mater. Sci. Technol., 2005, 21 (05): 724-728.  Abstract   HTML   PDF (6329KB) Industrial application of microwave, as a heating source for material processing, was reviewed. The feasibility of carbothermic reduction of zinc oxide concentrate, as well as the effect of operating parameters was investigated, using a home style microwave oven at 2.45 GHz. Zinc oxide concentrate does not effectively absorb microwave energy, while any source of carbon, which is used as the reduction agent, absorbs microwave energy very well. In this respect coke breeze was found to be the best, and thus, coke was used both as the reducing agent and the absorbent of microwave energy. It was also found that any increase in the carbon content and size, increases the reduction rate. Increasing the microwave power and the size of the sample could also increase the reduction rate. Further investigation shows that when zinc oxide is exposed to the microwave for some time, the rate of the reduction by conventional method increases.
 Select Effect of Gap Size on Coating Extrusion of Pb-GF Composite Wire by Theoretical Calculation and Experimental Investigation Wenbin FANG, Hongfei SUN, Erde WANG, Yaohong GENG J. Mater. Sci. Technol., 2005, 21 (05): 729-732.  Abstract   HTML   PDF (496KB) A new method using lead coated glass fiber to produce continuous wire for battery grid of electric vehicles (EVs) and hybrid electric vehicles (HEVs) was introduced. Under equal flow, both the maximum and minimum theoretical value of gap size were studied and estimation equation was established. The experimental results show that the gap size is a key parameter for the continuous coating extrusion process. Its maximum value (Hmax) is 0.24 mm and the minimum one (Hmin) is 0.12 mm. At a gap size of 0.18 mm, the maximum of metal extrusion per unit of time and optimal coating speed could be obtained.
 Select Forming Process of Strong Anisotropic Material Based on the Hydrodynamic Deep Drawing with Radial Pressure Lihui LANG, Joachim DANCKERT, Karl Brian NIELSEN J. Mater. Sci. Technol., 2005, 21 (05): 733-737.  Abstract   HTML   PDF (1490KB) The hydrodynamic deep drawing process enables net shape or near net shape forming of complicated sheet metal parts made from difficultly forming materials, such as aluminium or high strength steels. Based on the conventional hydrodynamic deep drawing process, a new process, hydrodynamic deep drawing process, in which radial pressure is applied to the rim of the blank, is proposed. This new process has been analysed using FEM simulations and the obtained results have been compared with the experimental results. The material used in the experiments was Al-Mg-Si alloy, and in the FEM-simulations the elastic-plastic behaviour of Al-Mg-Si alloy was modelled using Barlat's 89 yield criteria.
 Select Distortion Analysis of Single V-groove Butt Welding on Heat Treatable Aluminum Alloys C.M.Cheng, C.P.Chou, I.K.Lee, H.Y.Lin J. Mater. Sci. Technol., 2005, 21 (05): 738-742.  Abstract   HTML   PDF (4165KB) In this study we conducted single V-groove butt welding (GTAW) on three types of heat treatable aluminum alloys 2024-T351, 6061-T6 and 7075-T6 and compared the angular distortion levels of the three aluminum alloys at different Vee preparation angles with or without restraint. Experimental results demonstrated that when the Vee preparation angle was 0℃ (I-shaped groove), the angular distortion level of the restrained weldment can exceed that of the unrestrained weldments. Moreover, when the Vee preparation angle was 45℃, 60℃ or 90℃, the restrained weldment had lower angular distortion than the unrestrained weldments. The single Vee preparation angle (amount of filler metal) in butt welding affected the angular distortion of the weldment. Without restraint, the angular distortion tended to increase with the single Vee preparation angle. Meanwhile, the angular distortion tended to decrease when the single Vee preparation angle was 60℃. Additionally, a restrained weldment had high angular distortion when the single Vee preparation angle was 0℃. Notably, the angular distortion tended to reduce with increasing single Vee preparation angle. The angular distortion of the weldment was minimized at an angle of 60℃. However, the angular distortion increased when the Vee preparation angle exceeded 60℃. The high-temperature yield strength of a material also affected its angular distortion. Angular distortion increased with high-temperature yield strength. Experimental results also showed that, from the strongest to the weakest, the high-temperature yield strength of the three types of aluminum alloys followed the order 6061-T6 and 2024-T351>7075-T6.
 Select Metallurgical and Corrosion Properties of Explosively Welded Ti6Al4V/Low Carbon Steel Clad Nizamettin Kahraman, Behcet Gülenc J. Mater. Sci. Technol., 2005, 21 (05): 743-748.  Abstract   HTML   PDF (891KB) Titanium alloy (Ti6Al4V) and low carbon steel (LCS) were joined by explosive welding method using different ratios of explosive. Some metallurgical properties of joined samples were investigated. Joined samples were examined by means of optical microscope, scanning electron microscope (SEM) and tensile-shearing tests. Bending, tensile, hardness and corrosion behaviour of the samples were investigated. Separation was not occurred on the joining interface after tensile-shearing and bending tests. It is seen that hardness of both plates were increased with increasing explosive. It is found that increasing explosive ratio leads to an increase in corrosion. It is also found that corrosion rate was high at the beginning of the experiment but the rate of the corrosion decreased subsequently during the experiment.
 Select Influence of Surface Condition on Expulsion in Spot Welding AZ31B Magnesium Alloy Yarong WANG, Jicai FENG, Zhongdian ZHANG J. Mater. Sci. Technol., 2005, 21 (05): 749-752.  Abstract   HTML   PDF (278KB) Experiments were carried out to study the influence of surface condition on expulsion during the spot welding of AZ31B Mg alloy. A general electrical contact resistance theory for conductive rough surfaces and the relation between maximum temperature Tm in the contact and voltage-drop V across interface of two surfaces were employed to understand the reason of expulsion in Mg alloy spot welding. The main reason of expulsion is that the high electrical contact resistance induced by large roughness of the surface and oxide film covered on the surface leads to local melting of metal in the interface of two surfaces, and liquid metal of the local area ejected from the specimen under electrode force forms expulsion.
 Select Numerical Modelling and Experimental Investigation of Microse-gregation in Al-4.45 wt pct Cu: Effect of Dendrite Joining H.B.Dong J. Mater. Sci. Technol., 2005, 21 (05): 753-758.  Abstract   HTML   PDF (2751KB) A numerical model Alloy/M has been applied to investigate the microsegregation in Al-4.45 wt pct Cu alloy. The calculated data were compared with the experimental measurements for samples solidified at different cooling rates. Discrepancies in solute concentration occur between the experimental observations and calculated results. Reasons for the discrepancies were discussed, and the effect of dendrite joining at a later stage of solidification on the microsegregation was investigated. Calculations that have included this effect showed a better fit with experimental results.
 Select Microstructure Evolution in a Rapidly Solidified Cu85Fe15 Alloy Undercooled into the Metastable Miscibility Gap Jie HE, Jiuzhou ZHAO J. Mater. Sci. Technol., 2005, 21 (05): 759-762.  Abstract   HTML   PDF (437KB) A model has been developed to describe the microstructure evolution in the atomized droplets of Cu-Fe alloy during cooling through the metastable miscibility gap. Calculations have been performed for Cu85Fe15 alloy to investigate the process of liquid-liquid phase transformation. The numerical results indicate that the minority phase droplets are nucleated in a temperature region around the peak of the supersaturation. The average radius of the Fe-rich droplets decreases and the number density of the minority phase droplets increases with decreasing the atomized droplet size. The simulated results were compared with the experimental ones. The kinetic process of the liquid-liquid phase transformation was discussed in detail.
 Select Quantitative Evaluation for Drawability of Sheet Metal Zhiqing XIONG, Xuemei YANG J. Mater. Sci. Technol., 2005, 21 (05): 763-766.  Abstract   HTML   PDF (441KB) The theoretical evaluating method is given for the drawability of the sheet with normal anisotropy. The general solution on the cracking load of deep-drawing is deduced, which is based on three kinds of hardening curve of materials most in use. The distributions of stress and strain in the deformed region and the drawing force are obtained by the numerical method. The limiting drawing ratio is calculated through computer-aided simulating test. The experiments of deep-drawing to four kinds of sheet metals express that the relative errors between the predictive and the experimental results about the cracking load and the limiting drawing ratio are within 5%. The drawability of common sheet metals can be quantitatively evaluated in precise terms by means of the theory and the method advanced in this paper.
 Select Laboratory Study on the Removal of Fluorine from High Fluorine Bearing Zinc Oxide Ore Yaozhong LAN, Liaoyuan YE, Rose W.Smith J. Mater. Sci. Technol., 2005, 21 (05): 767-769.  Abstract   HTML   PDF (222KB) An ever increasing demand for zinc has resulted in worldwide efforts to exploit complex and lean grade reserves of zinc oxide ore. In this study experiments were done on zinc recovery from high-fluorine bearing zinc oxide ore. First the effect of different variables on fluorine removal was investigated. Optimum experimental conditions occurred when the temperature was 1173 K, roasting time was 90 min and air flow was at a velocity of 5 m/min, the fluorine removal from the samples reached over 93%. The results obtained indicate that fluorine removal is not enhanced by adding diluted sulfuric acid or water as a binder. Second the roasted materials were leached with a diluted sulfuric acid, neutralized, flocculated and filtrated. The residual fluorine content in the leached solutions was less than 38 mg/L, which satisfies the requirement of fluorine content in the leached solutions for the production of electrolytic zinc.
 Select Performance of Sn-Cu Alloy Anode at Low Temperature Jianguo REN, Weihua PU, Xiangming HE, Chunrong WAN, Changyin JIANG J. Mater. Sci. Technol., 2005, 21 (05): 770-772.  Abstract   HTML   PDF (739KB) Sn-Cu alloy anode was prepared by pulsed electrodeposition for lithium ion batteries, and its electrochemical performance was tested at low temperature. When temperature decreased from 25℃ to -20℃, the Sn-Cu alloy anode provided the capacity retentions of 76% in the electrolyte of 1 mol/L LiBF4/EC+EMC+γBL and 51% in the electrolyte of 1 mol/L LiPF6/EC+DMC+DEC. Under the same conditions, the graphite anode presented the capacity retentions of only 41% and 18%, respectively. The Sn-Cu alloy anode showed better performance in the electrolyte of 1 mol/L LiBF4/EC+EMC+γBL than in the electrolyte of 1 mol/L LiPF$_{6}$/EC+DMC+DEC, and kept much higher capacity retention than that of graphite at -20℃. The Sn-Cu alloy anode in the electrolyte of 1~mol/L LiBF4/EC+EMC+γBL (1:1:1, volume ratio) is promising for low temperature application of lithium batteries.
 Select Effect of Sn4+ B-Site Substitution on the Microstructure and Dielectric Properties of Ba(Mg1/3Ta2/3)O3 Microwave Ceramics Shunhua WU, Guoqing WANG, Shuang WANG, D, an LIU J. Mater. Sci. Technol., 2005, 21 (05): 773-775.  Abstract   HTML   PDF (435KB) The effect of Sn4+ (BaSnO3) B-site substitution on the microstructure and dielectric properties of Ba(Mg1/3Ta2/3O3 microwave ceramics was investigated. X-ray diffraction shows that a complex perovskite material Ba(Mg1/3Ta2/3)O3 was prepared. As Sn4+ content x increases in the (1-x) Ba(Mg1/3Ta2/3)O3-xBaSnO3 (x=0.00～0.20) system, the dielectric constant generally keeps unchanged, while TCF changes from positive to negative. Although the addition of Sn4+ reduces the ordering degree, Qf0 is still increased when the ceramics density increases. This trend implies that Qf0 of this system is mostly determined by ceramics density rather than ordering degree. After sintering at 1500℃ for 3 h, the system with x=0.15 was found to have excellent dielectric properties as follows: ε≈25, Qf0≥300,000 GHz at 7 GHz, TCF=-0.6×10-6℃.
 Select Conductivity of (NH4)3[CrMo6O24H6]•7H2O Treated by Nd Chemistry-Heated Diffused Permeation Xin LI, Zhonghua LI, Yuzhi GAO, Maomao ZHAO, Yuanru GUO, Baibin ZHOU J. Mater. Sci. Technol., 2005, 21 (05): 776-778.  Abstract   HTML   PDF (387KB) Rare earth co-permeation of (NH4)3[CrMo6O24H6]•7H2O was reported and the conductivity of (NH4)3[CrMo6O24H6] was improved by 6.734×109 times. X-ray fluorescence spectrometry (XRF), thermogravimetry-differential thermal analysis (TG-DTA), X-ray diffraction (XRD) have been used to character (NH4)3[CrMo6 O24H6] •7H2O and permeated sample. Experimental results showed that Nd could be permeated into the body of this sample and the XRD patterns showed great difference between (NH4)3[CrMo6O24H6] •7H2O and permeated sample. The structure of (NH4)3[CrMo6O24H6] •7H2O was destroyed and new compound MoN perhaps formed.
 Select Reactive Diffusion Bonding of SiCp/Al Composites by Insert Powder Layers with Eutectic Composition Jihua HUANG, Yueling DONG, Jiangang ZHANG, Yun WAN, Guoan ZHOU J. Mater. Sci. Technol., 2005, 21 (05): 779-781.  Abstract   HTML   PDF (1072KB) Mixed Al-Si and Al-Cu powders were investigated as insert layers to reactive diffusion bond SiCp/6063 metal matrix composite (MMC). The results show that SiCp/6063 MMC joints bonded by the insert layers of the mixed Al-Si and Al-Cu powders have a dense joining layer of high quality. The mass transfer between the bonded materials and insert layers during bonding leads to the hypoeutectic microstructure of the joining layers bonded by both the mixed Al-Si and Al-Cu powders with eutectic composition. At fixed bonding time (temperature), the shear strength of the joints by both insert layers of the mixed Al-Si and Al-Cu powders increases with increasing the bonding temperature (time), but get maxima at bonding temperature 600℃ (time 90~min).
 Select Al2O3/Al2O3 Joint Brazed with Al2O3-particulate-contained Composite Ag-Cu-Ti Filler Material Jianguo YANG, Hongyuan FANG, Xin WAN J. Mater. Sci. Technol., 2005, 21 (05): 782-784.  Abstract   HTML   PDF (903KB) Microstructure and interfacial reactions of Al2O3 joints brazed with Al2O3-particulate-contained composite Ag-Cu-Ti filler material were researched by scanning electron microscopy (SEM), electron probe microscopy analysis (EPMA), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The interfacial reaction layer thickness of joints brazed with conventional active filler metal and active composite filler materials with different volume fraction of Al2O3 particulate was also studied. The experimental results indicated although there were Al2O3 particulates added into active filler metals, the time dependence of interfacial layer growth of joints brazed with active composite filler material is t1/2 as described by Fickian law as the joints brazed with conventional active filler metal.
ISSN: 1005-0302
CN: 21-1315/TG
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